Programs & Examples On #Phrase

Maven dependencies are failing with a 501 error

I was using a clean install of Maven/Java on a Docker container.

For me, I had to cd $M2_HOME/conf and edit the settings.xml file there. Add the following block inside <mirrors>...</mirrors>


Fixing a systemd service 203/EXEC failure (no such file or directory)

I think I found the answer:

In the .service file, I needed to add /bin/bash before the path to the script.

For example, for backup.service:

ExecStart=/bin/bash /home/user/.scripts/

As opposed to:


I'm not sure why. Perhaps fish. On the other hand, I have another script running for my email, and the service file seems to run fine without /bin/bash. It does use instead, though.

Most of the tutorials I came across don't prepend /bin/bash, but I then saw this SO answer which had it, and figured it was worth a try.

The service file executes the script, and the timer is listed in systemctl --user list-timers, so hopefully this will work.

Update: I can confirm that everything is working now.

key_load_public: invalid format

Instead of directly saving the private key Go to Conversions and Export SSh Key. Had the same issue and this worked for me

Writing JSON object to a JSON file with fs.writeFileSync

I don't think you should use the synchronous approach, asynchronously writing data to a file is better also stringify the output if it's an object.

Note: If output is a string, then specify the encoding and remember the flag options as well.:

const fs = require('fs');
const content = JSON.stringify(output);

fs.writeFile('/tmp/phraseFreqs.json', content, 'utf8', function (err) {
    if (err) {
        return console.log(err);

    console.log("The file was saved!");

Added Synchronous method of writing data to a file, but please consider your use case. Asynchronous vs synchronous execution, what does it really mean?

const fs = require('fs');
const content = JSON.stringify(output);

fs.writeFileSync('/tmp/phraseFreqs.json', content);

gzip: stdin: not in gzip format tar: Child returned status 1 tar: Error is not recoverable: exiting now

cd /Whatever/Directory/Path/The/File/Is/In

chmod +x

sudo ./

It works

For more information refer

gpg failed to sign the data fatal: failed to write commit object [Git 2.10.0]

If gnupg2 and gpg-agent 2.x are used, be sure to set the environment variable GPG_TTY.

export GPG_TTY=$(tty)

See GPG’s documentation about common problems.

How to use a client certificate to authenticate and authorize in a Web API


Example from Microsoft:


This is how I got client certification working and checking that a specific Root CA had issued it as well as it being a specific certificate.

First I edited <src>\.vs\config\applicationhost.config and made this change: <section name="access" overrideModeDefault="Allow" />

This allows me to edit <system.webServer> in web.config and add the following lines which will require a client certification in IIS Express. Note: I edited this for development purposes, do not allow overrides in production.

For production follow a guide like this to set up the IIS:


  <access sslFlags="Ssl,SslNegotiateCert,SslRequireCert" />

API Controller:

public class ValuesController : ApiController
    // GET api/values
    public IHttpActionResult Get()
        return Ok("It works!");


public class RequireSpecificCertAttribute : AuthorizationFilterAttribute
    public override void OnAuthorization(HttpActionContext actionContext)
        if (actionContext.Request.RequestUri.Scheme != Uri.UriSchemeHttps)
            actionContext.Response = new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden)
                ReasonPhrase = "HTTPS Required"
            X509Certificate2 cert = actionContext.Request.GetClientCertificate();
            if (cert == null)
                actionContext.Response = new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden)
                    ReasonPhrase = "Client Certificate Required"

                X509Chain chain = new X509Chain();

                //Needed because the error "The revocation function was unable to check revocation for the certificate" happened to me otherwise
                chain.ChainPolicy = new X509ChainPolicy()
                    RevocationMode = X509RevocationMode.NoCheck,
                    var chainBuilt = chain.Build(cert);
                    Debug.WriteLine(string.Format("Chain building status: {0}", chainBuilt));

                    var validCert = CheckCertificate(chain, cert);

                    if (chainBuilt == false || validCert == false)
                        actionContext.Response = new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden)
                            ReasonPhrase = "Client Certificate not valid"
                        foreach (X509ChainStatus chainStatus in chain.ChainStatus)
                            Debug.WriteLine(string.Format("Chain error: {0} {1}", chainStatus.Status, chainStatus.StatusInformation));
                catch (Exception ex)


    private bool CheckCertificate(X509Chain chain, X509Certificate2 cert)
        var rootThumbprint = WebConfigurationManager.AppSettings["rootThumbprint"].ToUpper().Replace(" ", string.Empty);

        var clientThumbprint = WebConfigurationManager.AppSettings["clientThumbprint"].ToUpper().Replace(" ", string.Empty);

        //Check that the certificate have been issued by a specific Root Certificate
        var validRoot = chain.ChainElements.Cast<X509ChainElement>().Any(x => x.Certificate.Thumbprint.Equals(rootThumbprint, StringComparison.InvariantCultureIgnoreCase));

        //Check that the certificate thumbprint matches our expected thumbprint
        var validCert = cert.Thumbprint.Equals(clientThumbprint, StringComparison.InvariantCultureIgnoreCase);

        return validRoot && validCert;

Can then call the API with client certification like this, tested from another web project.

public class CertificateTestController : ApiController

    public IHttpActionResult Get()
        var handler = new WebRequestHandler();
        handler.ClientCertificateOptions = ClientCertificateOption.Manual;
        handler.UseProxy = false;
        var client = new HttpClient(handler);
        var result = client.GetAsync("https://localhost:44331/api/values").GetAwaiter().GetResult();
        var resultString = result.Content.ReadAsStringAsync().GetAwaiter().GetResult();
        return Ok(resultString);

    private static X509Certificate GetClientCert()
        X509Store store = null;
            store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
            store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly);

            var certificateSerialNumber= "?81 c6 62 0a 73 c7 b1 aa 41 06 a3 ce 62 83 ae 25".ToUpper().Replace(" ", string.Empty);

            //Does not work for some reason, could be culture related
            //var certs = store.Certificates.Find(X509FindType.FindBySerialNumber, certificateSerialNumber, true);

            //if (certs.Count == 1)
            //    var cert = certs[0];
            //    return cert;

            var cert = store.Certificates.Cast<X509Certificate>().FirstOrDefault(x => x.GetSerialNumberString().Equals(certificateSerialNumber, StringComparison.InvariantCultureIgnoreCase));

            return cert;

Could not create SSL/TLS secure channel, despite setting ServerCertificateValidationCallback

move this line: ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

Before this line: HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

Original post: KB4344167 security update breaks TLS Code

Guzzlehttp - How get the body of a response from Guzzle 6?

For get response in JSON format :

  1.$response = (string) $res->getBody();
      $response =json_decode($response); // Using this you can access any key like below
     $key_value = $response->key_name; //access key  

  2. $response = json_decode($res->getBody(),true);
     $key_value =   $response['key_name'];//access key

How to make the script wait/sleep in a simple way in unity

There are many ways to wait in Unity. It is really simple but I think it's worth covering most ways to do these:

1.With a coroutine and WaitForSeconds.

The is by far the simplest way. Put all the code that you need to wait for some time in a coroutine function then you can wait with WaitForSeconds. Note that in coroutine function, you call the function with StartCoroutine(yourFunction).

Example below will rotate 90 deg, wait for 4 seconds, rotate 40 deg and wait for 2 seconds, and then finally rotate rotate 20 deg.

void Start()

IEnumerator waiter()
    //Rotate 90 deg
    transform.Rotate(new Vector3(90, 0, 0), Space.World);

    //Wait for 4 seconds
    yield return new WaitForSeconds(4);

    //Rotate 40 deg
    transform.Rotate(new Vector3(40, 0, 0), Space.World);

    //Wait for 2 seconds
    yield return new WaitForSeconds(2);

    //Rotate 20 deg
    transform.Rotate(new Vector3(20, 0, 0), Space.World);

2.With a coroutine and WaitForSecondsRealtime.

The only difference between WaitForSeconds and WaitForSecondsRealtime is that WaitForSecondsRealtime is using unscaled time to wait which means that when pausing a game with Time.timeScale, the WaitForSecondsRealtime function would not be affected but WaitForSeconds would.

void Start()

IEnumerator waiter()
    //Rotate 90 deg
    transform.Rotate(new Vector3(90, 0, 0), Space.World);

    //Wait for 4 seconds
    yield return new WaitForSecondsRealtime(4);

    //Rotate 40 deg
    transform.Rotate(new Vector3(40, 0, 0), Space.World);

    //Wait for 2 seconds
    yield return new WaitForSecondsRealtime(2);

    //Rotate 20 deg
    transform.Rotate(new Vector3(20, 0, 0), Space.World);

Wait and still be able to see how long you have waited:

3.With a coroutine and incrementing a variable every frame with Time.deltaTime.

A good example of this is when you need the timer to display on the screen how much time it has waited. Basically like a timer.

It's also good when you want to interrupt the wait/sleep with a boolean variable when it is true. This is where yield break; can be used.

bool quit = false;

void Start()

IEnumerator waiter()
    float counter = 0;
    //Rotate 90 deg
    transform.Rotate(new Vector3(90, 0, 0), Space.World);

    //Wait for 4 seconds
    float waitTime = 4;
    while (counter < waitTime)
        //Increment Timer until counter >= waitTime
        counter += Time.deltaTime;
        Debug.Log("We have waited for: " + counter + " seconds");
        //Wait for a frame so that Unity doesn't freeze
        //Check if we want to quit this function
        if (quit)
            //Quit function
            yield break;
        yield return null;

    //Rotate 40 deg
    transform.Rotate(new Vector3(40, 0, 0), Space.World);

    //Wait for 2 seconds
    waitTime = 2;
    //Reset counter
    counter = 0;
    while (counter < waitTime)
        //Increment Timer until counter >= waitTime
        counter += Time.deltaTime;
        Debug.Log("We have waited for: " + counter + " seconds");
        //Check if we want to quit this function
        if (quit)
            //Quit function
            yield break;
        //Wait for a frame so that Unity doesn't freeze
        yield return null;

    //Rotate 20 deg
    transform.Rotate(new Vector3(20, 0, 0), Space.World);

You can still simplify this by moving the while loop into another coroutine function and yielding it and also still be able to see it counting and even interrupt the counter.

bool quit = false;

void Start()

IEnumerator waiter()
    //Rotate 90 deg
    transform.Rotate(new Vector3(90, 0, 0), Space.World);

    //Wait for 4 seconds
    float waitTime = 4;
    yield return wait(waitTime);

    //Rotate 40 deg
    transform.Rotate(new Vector3(40, 0, 0), Space.World);

    //Wait for 2 seconds
    waitTime = 2;
    yield return wait(waitTime);

    //Rotate 20 deg
    transform.Rotate(new Vector3(20, 0, 0), Space.World);

IEnumerator wait(float waitTime)
    float counter = 0;

    while (counter < waitTime)
        //Increment Timer until counter >= waitTime
        counter += Time.deltaTime;
        Debug.Log("We have waited for: " + counter + " seconds");
        if (quit)
            //Quit function
            yield break;
        //Wait for a frame so that Unity doesn't freeze
        yield return null;

Wait/Sleep until variable changes or equals to another value:

4.With a coroutine and the WaitUntil function:

Wait until a condition becomes true. An example is a function that waits for player's score to be 100 then loads the next level.

float playerScore = 0;
int nextScene = 0;

void Start()

IEnumerator sceneLoader()
    Debug.Log("Waiting for Player score to be >=100 ");
    yield return new WaitUntil(() => playerScore >= 10);
    Debug.Log("Player score is >=100. Loading next Leve");

    //Increment and Load next scene

5.With a coroutine and the WaitWhile function.

Wait while a condition is true. An example is when you want to exit app when the escape key is pressed.

void Start()

IEnumerator inputWaiter()
    Debug.Log("Waiting for the Exit button to be pressed");
    yield return new WaitWhile(() => !Input.GetKeyDown(KeyCode.Escape));
    Debug.Log("Exit button has been pressed. Leaving Application");

    //Exit program

void Quit()
    UnityEditor.EditorApplication.isPlaying = false;

6.With the Invoke function:

You can call tell Unity to call function in the future. When you call the Invoke function, you can pass in the time to wait before calling that function to its second parameter. The example below will call the feedDog() function after 5 seconds the Invoke is called.

void Start()
    Invoke("feedDog", 5);
    Debug.Log("Will feed dog after 5 seconds");

void feedDog()
    Debug.Log("Now feeding Dog");

7.With the Update() function and Time.deltaTime.

It's just like #3 except that it does not use coroutine. It uses the Update function.

The problem with this is that it requires so many variables so that it won't run every time but just once when the timer is over after the wait.

float timer = 0;
bool timerReached = false;

void Update()
    if (!timerReached)
        timer += Time.deltaTime;

    if (!timerReached && timer > 5)
        Debug.Log("Done waiting");

        //Set to false so that We don't run this again
        timerReached = true;

void feedDog()
    Debug.Log("Now feeding Dog");

There are still other ways to wait in Unity but you should definitely know the ones mentioned above as that makes it easier to make games in Unity. When to use each one depends on the circumstances.

For your particular issue, this is the solution:

IEnumerator showTextFuntion()
    TextUI.text = "Welcome to Number Wizard!";
    yield return new WaitForSeconds(3f);
    TextUI.text = ("The highest number you can pick is " + max);
    yield return new WaitForSeconds(3f);
    TextUI.text = ("The lowest number you can pick is " + min);

And to call/start the coroutine function from your start or Update function, you call it with

StartCoroutine (showTextFuntion());

gpg decryption fails with no secret key error

This error will arise when using the utility pass if the terminal window is too small!

Just make the terminal window a few lines taller.

Very confusing.

How to get content body from a httpclient call?

If you are not wanting to use async you can add .Result to force the code to execute synchronously:

private string GetResponseString(string text)
    var httpClient = new HttpClient();

    var parameters = new Dictionary<string, string>();
    parameters["text"] = text;

    var response = httpClient.PostAsync(BaseUri, new FormUrlEncodedContent(parameters)).Result;
    var contents = response.Content.ReadAsStringAsync().Result;

    return contents;

Why am I getting a "401 Unauthorized" error in Maven?

As stated in @John's answer, the fact that there is already a 0.1.2-SNAPSHOT, interfered with my new non-SNAPSHOT version 0.1.2. Since the 401 Unauthorized error is nebulous and unhelpful--and is normally associated to user/pass problems--it's no surprise that I was unable to figure this out on my own.

Changing the version to 0.1.3 brings me back to my original error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-install-plugin:2.4:install (default-install) on project xbnjava: Failed to install artifact com.github.aliteralmind:xbnjava:jar:0.1.3: R:\jeffy\programming\build\xbnjava-0.1.3\download\xbnjava-0.1.3-all.jar (The system cannot find the path specified) -> [Help 1].

A sonatype support person also recommended that I remove the <parent> block from my POM (it's only there because it's in the one from ez-vcard, which is what I started with) and replace my <distributionManagement> block with

and then make sure that lines up with what's in your settings.xml:

After doing this, running mvn deploy actually uploaded one of my jars for the very first time!!!


[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building XBN-Java 0.1.3
[INFO] ------------------------------------------------------------------------
[INFO] --- build-helper-maven-plugin:1.8:attach-artifact (attach-artifacts) @ xbnjava ---
[INFO] --- maven-install-plugin:2.4:install (default-install) @ xbnjava ---
[INFO] Installing R:\jeffy\programming\sandbox\z__for_git_commit_only\xbnjava\pom.xml to C:\Users\jeffy\.m2\repository\com\github\aliteralmind\xbnjava\0.1.3\xbnjava-0.1.3.pom
[INFO] Installing R:\jeffy\programming\build\xbnjava-0.1.3\download\xbnjava-0.1.3.jar to C:\Users\jeffy\.m2\repository\com\github\aliteralmind\xbnjava\0.1.3\xbnjava-0.1.3.jar
[INFO] --- maven-deploy-plugin:2.7:deploy (default-deploy) @ xbnjava ---
2/6 KB
4/6 KB
6/6 KB

Uploaded: (6 KB at 4.6 KB/sec)
310/310 B

Downloaded: (310 B at 1.6 KB/sec)
310/310 B

Uploaded: (310 B at 1.4 KB/sec)
2/630 KB
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(Success portion:)

Uploaded: (630 KB at 474.7 KB/sec)
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.632 s
[INFO] Finished at: 2014-07-18T15:09:25-04:00
[INFO] Final Memory: 6M/19M
[INFO] ------------------------------------------------------------------------

Here's the full updated POM:

<project xmlns="" xmlns:xsi="" xsi:schemaLocation="">
     <name>Jeff Epstein</name>
  <description>XBN-Java is a collection of generically-useful backend (server side, non-GUI) programming utilities, featuring RegexReplacer and FilteredLineIterator. XBN-Java is the foundation of Codelet (</description>

        <name>Lesser General Public License (LGPL) version 3.0</name>
        <name>Apache Software License (ASL) version 2.0</name>

        <name>Jeff Epstein</name>
        <email>[email protected]</email>
           <role>Lead Developer</role>

     <system>GitHub Issue Tracker</system>


     <connection>scm:git:[email protected]:aliteralmind/xbnjava.git</connection>
     <url>scm:git:[email protected]:aliteralmind/xbnjava.git</url>
     <developerConnection>scm:git:[email protected]:aliteralmind/xbnjava.git</developerConnection>


     This profile will sign the JAR file, sources file, and javadocs file using the GPG key on the local machine.

That's one big Maven problem out of the way. Only 627 more to go.

How to encrypt and decrypt String with my passphrase in Java (Pc not mobile platform)?

Use This This Will work For sure

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class ProtectedConfigFile {

    private static final char[] PASSWORD = "enfldsgbnlsngdlksdsgm".toCharArray();
    private static final byte[] SALT = { (byte) 0xde, (byte) 0x33, (byte) 0x10, (byte) 0x12, (byte) 0xde, (byte) 0x33,
            (byte) 0x10, (byte) 0x12, };

    public static void main(String[] args) throws Exception {
        String originalPassword = "Aman";
        System.out.println("Original password: " + originalPassword);
        String encryptedPassword = encrypt(originalPassword);
        System.out.println("Encrypted password: " + encryptedPassword);
        String decryptedPassword = decrypt(encryptedPassword);
        System.out.println("Decrypted password: " + decryptedPassword);

    private static String encrypt(String property) throws GeneralSecurityException, UnsupportedEncodingException {
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        SecretKey key = keyFactory.generateSecret(new PBEKeySpec(PASSWORD));
        Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
        pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
        return base64Encode(pbeCipher.doFinal(property.getBytes("UTF-8")));

    private static String base64Encode(byte[] bytes) {
        // NB: This class is internal, and you probably should use another impl
        return new BASE64Encoder().encode(bytes);

    private static String decrypt(String property) throws GeneralSecurityException, IOException {
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
        SecretKey key = keyFactory.generateSecret(new PBEKeySpec(PASSWORD));
        Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
        pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(SALT, 20));
        return new String(pbeCipher.doFinal(base64Decode(property)), "UTF-8");

    private static byte[] base64Decode(String property) throws IOException {
        // NB: This class is internal, and you probably should use another impl
        return new BASE64Decoder().decodeBuffer(property);


use "netsh wlan set hostednetwork ..." to create a wifi hotspot and the authentication can't work correctly


netsh wlan set hostednetwork mode=allow ssid=hotspotname key=123456789

perform all steps in proper order.. for more detail with image ,have a look..this might help to setup hotspot correctly.

SSH Key - Still asking for password and passphrase

For Mac OSX Sierra, I found that the fixes suggested in the github issue for Open Radar fixed my problem. Seems like Sierra changed the default behavior (I started having this problem after upgrading).

This one I found especially useful:

ssh-add -A 

This resulted in my identity being added to the agent, after I ran

ssh-add -K {/path/to/key}

To summarize, in OSX.12:

ssh-add -K {/path/to/key}
ssh-add -A 

should result in:

Identity added: {/path/to/file} ({/path/to/file})

EDIT: I noticed the next time I did a full reboot (aka the agent stopped and restarted) this no longer worked. The more complete solution is what @ChrisJF mentioned above: creating a ~/.ssh/config file. Here's the output of mine:

$ cat ~/.ssh/config
Host *
  UseKeychain yes
  AddKeysToAgent yes
  IdentityFile ~/.ssh/id_rsa

You can add as many IdentityFile entries as you need, but this is the default setup. This is the "trending" answer on the openradar link above, ATM, as well.

Disable password authentication for SSH

The one-liner to disable SSH password authentication:

sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/g' /etc/ssh/sshd_config && service ssh restart

scp copy directory to another server with private key auth

or you can also do ( for pem file )

 scp -r -i file.pem [email protected]:/home/backup /home/user/Desktop/

String.Format not work in TypeScript

I solved it like this;

1.Created a function

export function FormatString(str: string, ...val: string[]) {
  for (let index = 0; index < val.length; index++) {
    str = str.replace(`{${index}}`, val[index]);
  return str;

2.Used it like the following;

FormatString("{0} is {1} {2}", "This", "formatting", "hack");

What is difference between MVC, MVP & MVVM design pattern in terms of coding c#

Some basic differences can be written in short:


Traditional MVC is where there is a

  1. Model: Acts as the model for data
  2. View : Deals with the view to the user which can be the UI
  3. Controller: Controls the interaction between Model and View, where view calls the controller to update model. View can call multiple controllers if needed.


Similar to traditional MVC but Controller is replaced by Presenter. But the Presenter, unlike Controller is responsible for changing the view as well. The view usually does not call the presenter.


The difference here is the presence of View Model. It is kind of an implementation of Observer Design Pattern, where changes in the model are represented in the view as well, by the VM. Eg: If a slider is changed, not only the model is updated but the data which may be a text, that is displayed in the view is updated as well. So there is a two-way data binding.

git push to specific branch

git push origin amd_qlp_tester will work for you. If you just type git push, then the remote of the current branch is the default value.

Syntax of push looks like this - git push <remote> <branch>. If you look at your remote in .git/config file, you will see an entry [remote "origin"] which specifies url of the repository. So, in the first part of command you will tell Git where to find repository for this project, and then you just specify a branch.

Add Header and Footer for PDF using iTextsharp

Easy codes that work successfully:

protected void Page_Load(object sender, EventArgs e)
 using (MemoryStream ms = new MemoryStream())
  iTextSharp.text.Document doc = new iTextSharp.text.Document(iTextSharp.text.PageSize.A4, 36, 36, 54, 54);
  iTextSharp.text.pdf.PdfWriter writer = iTextSharp.text.pdf.PdfWriter.GetInstance(doc, ms);
  writer.PageEvent = new HeaderFooter();
  // make your document content..

  // output
  Response.ContentType = "application/pdf;";
  Response.AddHeader("Content-Disposition", "attachment; filename=clientfilename.pdf");
  byte[] pdf = ms.ToArray();
  Response.OutputStream.Write(pdf, 0, pdf.Length);
class HeaderFooter : PdfPageEventHelper
public override void OnEndPage(PdfWriter writer, Document document)

    // Make your table header using PdfPTable and name that tblHeader
    tblHeader.WriteSelectedRows(0, -1, page.Left + document.LeftMargin, page.Top, writer.DirectContent);
    // Make your table footer using PdfPTable and name that tblFooter
    tblFooter.WriteSelectedRows(0, -1, page.Left + document.LeftMargin, writer.PageSize.GetBottom(document.BottomMargin), writer.DirectContent);

What is the difference between `` and `Enum.toString()`?

Use toString when you need to display the name to the user.

Use name when you need the name for your program itself, e.g. to identify and differentiate between different enum values.

Catching exceptions from Guzzle

You need to add a extra parameter with http_errors => false

$request = $client->get($url, ['http_errors' => false]);

Error LNK2019: Unresolved External Symbol in Visual Studio

I was getting this error after adding the include files and linking the library. It was because the lib was built with non-unicode and my application was unicode. Matching them fixed it.

How to define a Sql Server connection string to use in VB.NET?


Dim connectionString AS String = "Server=my_server;Database=name_of_db;User Id=user_name;Password=my_password"

And replace my_server, name_of_db, user_name and my_password with your values.

then Using sqlCon = New SqlConnection(connectionString) should work

also I think your SQL is wrong, it should be SET clickCount= clickCount + 1 I think.

And on a general note, the page you link to has a link called Connection String which shows you how to do this.

Getting content/message from HttpResponseMessage

I think the easiest approach is just to change the last line to

txtBlock.Text = await response.Content.ReadAsStringAsync(); //right!

This way you don't need to introduce any stream readers and you don't need any extension methods.

How to check if two words are anagrams

IMHO, the most efficient solution was provided by @Siguza, I have extended it to cover strings with space e.g: "William Shakespeare", "I am a weakish speller", "School master", "The classroom"

public int getAnagramScore(String word, String anagram) {

        if (word == null || anagram == null) {
            throw new NullPointerException("Both, word and anagram, must be non-null");

        char[] wordArray = word.trim().toLowerCase().toCharArray();
        char[] anagramArray = anagram.trim().toLowerCase().toCharArray();

        int[] alphabetCountArray = new int[26];

        int reference = 'a';

        for (int i = 0; i < wordArray.length; i++) {
            if (!Character.isWhitespace(wordArray[i])) {
                alphabetCountArray[wordArray[i] - reference]++;
        for (int i = 0; i < anagramArray.length; i++) {
            if (!Character.isWhitespace(anagramArray[i])) {
                alphabetCountArray[anagramArray[i] - reference]--;

        for (int i = 0; i < 26; i++)
            if (alphabetCountArray[i] != 0)
                return 0;

        return word.length();


How to include "zero" / "0" results in COUNT aggregate?

You want an outer join for this (and you need to use person as the "driving" table)

SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person 
  LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;

The reason why this is working, is that the outer (left) join will return NULL for those persons that do not have an appointment. The aggregate function count() will not count NULL values and thus you'll get a zero.

If you want to learn more about outer joins, here is a nice tutorial:

Setting Elastic search limit to "unlimited"

Another approach is to first do a searchType: 'count', then and then do a normal search with size set to results.count.

The advantage here is it avoids depending on a magic number for UPPER_BOUND as suggested in this similar SO question, and avoids the extra overhead of building too large of a priority queue that Shay Banon describes here. It also lets you keep your results sorted, unlike scan.

The biggest disadvantage is that it requires two requests. Depending on your circumstance, this may be acceptable.

how to set width for PdfPCell in ItextSharp

Try something like this

PdfPCell cell;
PdfPTable tableHeader;
PdfPTable tmpTable;
PdfPTable table = new PdfPTable(10) { WidthPercentage = 100, RunDirection = PdfWriter.RUN_DIRECTION_LTR, ExtendLastRow = false };

// row 1 / cell 1 (merge)
PdfPCell _c = new PdfPCell(new Phrase("SER. No")) { Rotation = -90, VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER, BorderWidth = 1 };
_c.Rowspan = 2;


// row 1 / cell 2
_c = new PdfPCell(new Phrase("TYPE OF SHIPPING")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 1 / cell 3
_c = new PdfPCell(new Phrase("ORDER NO.")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 1 / cell 4
_c = new PdfPCell(new Phrase("QTY.")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 1 / cell 5
_c = new PdfPCell(new Phrase("DISCHARGE PPORT")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 1 / cell 6 (merge)
_c = new PdfPCell(new Phrase("DESCRIPTION OF GOODS")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };
_c.Rowspan = 2;

// row 1 / cell 7
_c = new PdfPCell(new Phrase("LINE DOC. RECI. DATE")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 1 / cell 8 (merge)
_c = new PdfPCell(new Phrase("OWNER DOC. RECI. DATE")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };
_c.Rowspan = 2;

// row 1 / cell 9 (merge)
_c = new PdfPCell(new Phrase("CLEARANCE DATE")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };
_c.Rowspan = 2;

// row 1 / cell 10 (merge)
_c = new PdfPCell(new Phrase("CUSTOM PERMIT NO.")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };
_c.Rowspan = 2;

// row 2 / cell 2
_c = new PdfPCell(new Phrase("AWB / BL NO.")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 2 / cell 3
_c = new PdfPCell(new Phrase("COMPLEX NAME")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 2 / cell 4
_c = new PdfPCell(new Phrase("G.W Kgs.")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 2 / cell 5
_c = new PdfPCell(new Phrase("DESTINATON")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };

// row 2 / cell 7
_c = new PdfPCell(new Phrase("OWNER DOC. RECI. DATE")) { VerticalAlignment = Element.ALIGN_MIDDLE, HorizontalAlignment = Element.ALIGN_CENTER };


You might need to re-adjust slightly on the widths and borders but that is a one shot to do.

Is there an online application that automatically draws tree structures for phrases/sentences?

There are lots of options out there. Many of which are available as downloadable software as well as public websites. I do not think many of them expect to be used as API's unless they explicitly state that.

The one that I found effective was Enju which did not have the character limit that the Marc's Carnagie Mellon link had. Marc also mentioned a VISL scanner in comments, but that requires java in the browser, which is a non-starter for me.

Note that recently, Google has offered a new NLP Machine Learning API that providers amoung other features, a automatic sentence parser. I will likely not update this answer again, especially since the question is closed, but I suspect that the other big ML cloud stacks will soon support the same.

How to leave space in HTML

As others already answered, $nbsp; will output no-break space character. Here is w3 docs for &nbsp and others.

However there is other ways to do it and nowdays i would prefer using CSS stylesheets. There is also w3c tutorials for beginners.

With CSS you can do it like this:

        <title>CSS test</title>
        <style type="text/css">
            p { word-spacing: 40px; }
        <p>Hello World! Enough space between words, what do you think about it?</p>

What is the difference between JVM, JDK, JRE & OpenJDK?

JVM : A specification which describes the the way/resources to run a java program. Actually executes the byte code and make java platform independent. In doing so, it is different for different platform. JVM for windows cannot work as JVM for UNIX.

JRE : Implementation of JVM. (JVM + run time libraries)

JDK : JRE + java compiler and other essential tools to build a java program from scratch

How to enter command with password for git pull?

Note that the way the git credential helper "store" will store the unencrypted passwords changes with Git 2.5+ (Q2 2014).
See commit 17c7f4d by Junio C Hamano (gitster)


Tweak the sample "store" backend of the credential helper to honor XDG configuration file locations when specified.

The doc now say:

If not specified:

  • credentials will be searched for from ~/.git-credentials and $XDG_CONFIG_HOME/git/credentials, and
  • credentials will be written to ~/.git-credentials if it exists, or $XDG_CONFIG_HOME/git/credentials if it exists and the former does not.

When should null values of Boolean be used?

Wrapper classes for primitives can be used where objects are required, collections are a good sample.

Imagine you need for some reason store a sequence of boolean in an ArrayList, this can be done by boxing boolean in Boolean.

There is a few words about this here

From documentation:

As any Java programmer knows, you can’t put an int (or other primitive value) into a collection. Collections can only hold object references, so you have to box primitive values into the appropriate wrapper class (which is Integer in the case of int). When you take the object out of the collection, you get the Integer that you put in; if you need an int, you must unbox the Integer using the intValue method. All of this boxing and unboxing is a pain, and clutters up your code. The autoboxing and unboxing feature automates the process, eliminating the pain and the clutter.

Should I use <i> tag for icons instead of <span>?

I thought this looked pretty bad - because I was working on a Joomla template recently and I kept getting the template failing W3C because it was using the <i> tag and that had deprecated, as it's original use was to italicize something, which is now done through CSS not HTML any more.

It does make really bad practice because when I saw it I went through the template and changed all the <i> tags to <span style="font-style:italic"> instead and then wondered why the entire template looked strange.

This is the main reason it is a bad idea to use the <i> tag in this way - you never know who is going to look at your work afterwards and "assume" that what you were really trying to do is italicize the text rather than display an icon. I've just put some icons in a website and I did it with the following code

<img class="icon" src="electricity.jpg" alt="Electricity" title="Electricity">

that way I've got all my icons in one class so any changes I make affects all the icons (say I wanted them larger or smaller, or rounded borders, etc), the alt text gives screen readers the chance to tell the person what the icon is rather than possibly getting just "text in italics, end of italics" (I don't exactly know how screen readers read screens but I guess it's something like that), and the title also gives the user a chance to mouse over the image and get a tooltip telling them what the icon is in case they can't figure it out. Much better than using <i> - and also it passes W3C standard.

Maven error: Not authorized, ReasonPhrase:Unauthorized

You have an old password in the settings.xml. It is trying to connect to the repositories, but is not able to, since the password is not updated. Once you update and re-run the command, you should be good.

How to reset or change the passphrase for a GitHub SSH key?

You can change the passphrase for your private key by doing:

ssh-keygen -f ~/.ssh/id_rsa -p

Git keeps asking me for my ssh key passphrase

Another possible solution that is not mentioned above is to check your remote with the following command:

git remote -v

If the remote does not start with git but starts with https you might want to change it to git by following the example below.

git remote -v // origin is
git remote set-url origin [email protected]:user/myrepo.git
git remote -v // check if remote is changed

In Jenkins, how to checkout a project into a specific directory (using GIT)

In the new Pipeline flow, following image may help ..

enter image description here

Append an array to another array in JavaScript

If you want to modify the original array instead of returning a new array, use .push()...

array1.push.apply(array1, array2);
array1.push.apply(array1, array3);

I used .apply to push the individual members of arrays 2 and 3 at once.


array1.push.apply(array1, array2.concat(array3));

To deal with large arrays, you can do this in batches.

for (var n = 0, to_add = array2.concat(array3); n < to_add.length; n+=300) {
    array1.push.apply(array1, to_add.slice(n, n+300));

If you do this a lot, create a method or function to handle it.

var push_apply = Function.apply.bind([].push);
var slice_call =[].slice);

Object.defineProperty(Array.prototype, "pushArrayMembers", {
    value: function() {
        for (var i = 0; i < arguments.length; i++) {
            var to_add = arguments[i];
            for (var n = 0; n < to_add.length; n+=300) {
                push_apply(this, slice_call(to_add, n, n+300));

and use it like this:

array1.pushArrayMembers(array2, array3);

var push_apply = Function.apply.bind([].push);_x000D_
var slice_call =[].slice);_x000D_
Object.defineProperty(Array.prototype, "pushArrayMembers", {_x000D_
    value: function() {_x000D_
        for (var i = 0; i < arguments.length; i++) {_x000D_
            var to_add = arguments[i];_x000D_
            for (var n = 0; n < to_add.length; n+=300) {_x000D_
                push_apply(this, slice_call(to_add, n, n+300));_x000D_
var array1 = ['a','b','c'];_x000D_
var array2 = ['d','e','f'];_x000D_
var array3 = ['g','h','i'];_x000D_
array1.pushArrayMembers(array2, array3);_x000D_
document.body.textContent = JSON.stringify(array1, null, 4);

Bloomberg Open API

The API's will provide full access to LIVE data, and developers can thus provide applications and develop against the API without paying licencing fees. Consumers will pay for any data received from the apps provided by third party developers, and so BB will grow their audience and revenue in that way.

NOTE: Bloomberg is offering this programming interface (BLPAPI) under a free-use license. This license does not include nor provide access to any Bloomberg data or content.


Why are elementwise additions much faster in separate loops than in a combined loop?

The Original Question

Why is one loop so much slower than two loops?


Case 1 is a classic interpolation problem that happens to be an inefficient one. I also think that this was one of the leading reasons why many machine architectures and developers ended up building and designing multi-core systems with the ability to do multi-threaded applications as well as parallel programming.

Looking at it from this kind of an approach without involving how the hardware, OS, and compiler(s) work together to do heap allocations that involve working with RAM, cache, page files, etc.; the mathematics that is at the foundation of these algorithms shows us which of these two is the better solution.

We can use an analogy of a Boss being a Summation that will represent a For Loop that has to travel between workers A & B.

We can easily see that Case 2 is at least half as fast if not a little more than Case 1 due to the difference in the distance that is needed to travel and the time taken between the workers. This math lines up almost virtually and perfectly with both the benchmark times as well as the number of differences in assembly instructions.

I will now begin to explain how all of this works below.

Assessing The Problem

The OP's code:

const int n=100000;

for(int j=0;j<n;j++){
    a1[j] += b1[j];
    c1[j] += d1[j];


for(int j=0;j<n;j++){
    a1[j] += b1[j];
for(int j=0;j<n;j++){
    c1[j] += d1[j];

The Consideration

Considering the OP's original question about the two variants of the for loops and his amended question towards the behavior of caches along with many of the other excellent answers and useful comments; I'd like to try and do something different here by taking a different approach about this situation and problem.

The Approach

Considering the two loops and all of the discussion about cache and page filing I'd like to take another approach as to looking at this from a different perspective. One that doesn't involve the cache and page files nor the executions to allocate memory, in fact, this approach doesn't even concern the actual hardware or the software at all.

The Perspective

After looking at the code for a while it became quite apparent what the problem is and what is generating it. Let's break this down into an algorithmic problem and look at it from the perspective of using mathematical notations then apply an analogy to the math problems as well as to the algorithms.

What We Do Know

We know is that this loop will run 100,000 times. We also know that a1, b1, c1 & d1 are pointers on a 64-bit architecture. Within C++ on a 32-bit machine, all pointers are 4 bytes and on a 64-bit machine, they are 8 bytes in size since pointers are of a fixed length.

We know that we have 32 bytes in which to allocate for in both cases. The only difference is we are allocating 32 bytes or two sets of 2-8 bytes on each iteration wherein the second case we are allocating 16 bytes for each iteration for both of the independent loops.

Both loops still equal 32 bytes in total allocations. With this information let's now go ahead and show the general math, algorithms, and analogy of these concepts.

We do know the number of times that the same set or group of operations that will have to be performed in both cases. We do know the amount of memory that needs to be allocated in both cases. We can assess that the overall workload of the allocations between both cases will be approximately the same.

What We Don't Know

We do not know how long it will take for each case unless if we set a counter and run a benchmark test. However, the benchmarks were already included from the original question and from some of the answers and comments as well; and we can see a significant difference between the two and this is the whole reasoning for this proposal to this problem.

Let's Investigate

It is already apparent that many have already done this by looking at the heap allocations, benchmark tests, looking at RAM, cache, and page files. Looking at specific data points and specific iteration indices were also included and the various conversations about this specific problem have many people starting to question other related things about it. How do we begin to look at this problem by using mathematical algorithms and applying an analogy to it? We start off by making a couple of assertions! Then we build out our algorithm from there.

Our Assertions:

  • We will let our loop and its iterations be a Summation that starts at 1 and ends at 100000 instead of starting with 0 as in the loops for we don't need to worry about the 0 indexing scheme of memory addressing since we are just interested in the algorithm itself.
  • In both cases we have four functions to work with and two function calls with two operations being done on each function call. We will set these up as functions and calls to functions as the following: F1(), F2(), f(a), f(b), f(c) and f(d).

The Algorithms:

1st Case: - Only one summation but two independent function calls.

Sum n=1 : [1,100000] = F1(), F2();
                       F1() = { f(a) = f(a) + f(b); }
                       F2() = { f(c) = f(c) + f(d); }

2nd Case: - Two summations but each has its own function call.

Sum1 n=1 : [1,100000] = F1();
                        F1() = { f(a) = f(a) + f(b); }

Sum2 n=1 : [1,100000] = F1();
                        F1() = { f(c) = f(c) + f(d); }

If you noticed F2() only exists in Sum from Case1 where F1() is contained in Sum from Case1 and in both Sum1 and Sum2 from Case2. This will be evident later on when we begin to conclude that there is an optimization that is happening within the second algorithm.

The iterations through the first case Sum calls f(a) that will add to its self f(b) then it calls f(c) that will do the same but add f(d) to itself for each 100000 iterations. In the second case, we have Sum1 and Sum2 that both act the same as if they were the same function being called twice in a row.

In this case we can treat Sum1 and Sum2 as just plain old Sum where Sum in this case looks like this: Sum n=1 : [1,100000] { f(a) = f(a) + f(b); } and now this looks like an optimization where we can just consider it to be the same function.

Summary with Analogy

With what we have seen in the second case it almost appears as if there is optimization since both for loops have the same exact signature, but this isn't the real issue. The issue isn't the work that is being done by f(a), f(b), f(c), and f(d). In both cases and the comparison between the two, it is the difference in the distance that the Summation has to travel in each case that gives you the difference in execution time.

Think of the for loops as being the summations that does the iterations as being a Boss that is giving orders to two people A & B and that their jobs are to meat C & D respectively and to pick up some package from them and return it. In this analogy, the for loops or summation iterations and condition checks themselves don't actually represent the Boss. What actually represents the Boss is not from the actual mathematical algorithms directly but from the actual concept of Scope and Code Block within a routine or subroutine, method, function, translation unit, etc. The first algorithm has one scope where the second algorithm has two consecutive scopes.

Within the first case on each call slip, the Boss goes to A and gives the order and A goes off to fetch B's package then the Boss goes to C and gives the orders to do the same and receive the package from D on each iteration.

Within the second case, the Boss works directly with A to go and fetch B's package until all packages are received. Then the Boss works with C to do the same for getting all of D's packages.

Since we are working with an 8-byte pointer and dealing with heap allocation let's consider the following problem. Let's say that the Boss is 100 feet from A and that A is 500 feet from C. We don't need to worry about how far the Boss is initially from C because of the order of executions. In both cases, the Boss initially travels from A first then to B. This analogy isn't to say that this distance is exact; it is just a useful test case scenario to show the workings of the algorithms.

In many cases when doing heap allocations and working with the cache and page files, these distances between address locations may not vary that much or they can vary significantly depending on the nature of the data types and the array sizes.

The Test Cases:

First Case: On first iteration the Boss has to initially go 100 feet to give the order slip to A and A goes off and does his thing, but then the Boss has to travel 500 feet to C to give him his order slip. Then on the next iteration and every other iteration after the Boss has to go back and forth 500 feet between the two.

Second Case: The Boss has to travel 100 feet on the first iteration to A, but after that, he is already there and just waits for A to get back until all slips are filled. Then the Boss has to travel 500 feet on the first iteration to C because C is 500 feet from A. Since this Boss( Summation, For Loop ) is being called right after working with A he then just waits there as he did with A until all of C's order slips are done.

The Difference In Distances Traveled

const n = 100000
distTraveledOfFirst = (100 + 500) + ((n-1)*(500 + 500);
// Simplify
distTraveledOfFirst = 600 + (99999*100);
distTraveledOfFirst = 600 + 9999900;
distTraveledOfFirst =  10000500;
// Distance Traveled On First Algorithm = 10,000,500ft

distTraveledOfSecond = 100 + 500 = 600;
// Distance Traveled On Second Algorithm = 600ft;

The Comparison of Arbitrary Values

We can easily see that 600 is far less than 10 million. Now, this isn't exact, because we don't know the actual difference in distance between which address of RAM or from which cache or page file each call on each iteration is going to be due to many other unseen variables. This is just an assessment of the situation to be aware of and looking at it from the worst-case scenario.

From these numbers it would almost appear as if algorithm one should be 99% slower than algorithm two; however, this is only the Boss's part or responsibility of the algorithms and it doesn't account for the actual workers A, B, C, & D and what they have to do on each and every iteration of the Loop. So the boss's job only accounts for about 15 - 40% of the total work being done. The bulk of the work that is done through the workers has a slightly bigger impact towards keeping the ratio of the speed rate differences to about 50-70%

The Observation: - The differences between the two algorithms

In this situation, it is the structure of the process of the work being done. It goes to show that Case 2 is more efficient from both the partial optimization of having a similar function declaration and definition where it is only the variables that differ by name and the distance traveled.

We also see that the total distance traveled in Case 1 is much farther than it is in Case 2 and we can consider this distance traveled our Time Factor between the two algorithms. Case 1 has considerable more work to do than Case 2 does.

This is observable from the evidence of the assembly instructions that were shown in both cases. Along with what was already stated about these cases, this doesn't account for the fact that in Case 1 the boss will have to wait for both A & C to get back before he can go back to A again for each iteration. It also doesn't account for the fact that if A or B is taking an extremely long time then both the Boss and the other worker(s) are idle waiting to be executed.

In Case 2 the only one being idle is the Boss until the worker gets back. So even this has an impact on the algorithm.

The OP's Amended Question(s)

EDIT: The question turned out to be of no relevance, as the behavior severely depends on the sizes of the arrays (n) and the CPU cache. So if there is further interest, I rephrase the question:

Could you provide some solid insight into the details that lead to the different cache behaviors as illustrated by the five regions on the following graph?

It might also be interesting to point out the differences between CPU/cache architectures, by providing a similar graph for these CPUs.

Regarding These Questions

As I have demonstrated without a doubt, there is an underlying issue even before the Hardware and Software becomes involved.

Now as for the management of memory and caching along with page files, etc. which all work together in an integrated set of systems between the following:

  • The architecture (hardware, firmware, some embedded drivers, kernels and assembly instruction sets).
  • The OS (file and memory management systems, drivers and the registry).
  • The compiler (translation units and optimizations of the source code).
  • And even the source code itself with its set(s) of distinctive algorithms.

We can already see that there is a bottleneck that is happening within the first algorithm before we even apply it to any machine with any arbitrary architecture, OS, and programmable language compared to the second algorithm. There already existed a problem before involving the intrinsics of a modern computer.

The Ending Results

However; it is not to say that these new questions are not of importance because they themselves are and they do play a role after all. They do impact the procedures and the overall performance and that is evident with the various graphs and assessments from many who have given their answer(s) and or comment(s).

If you paid attention to the analogy of the Boss and the two workers A & B who had to go and retrieve packages from C & D respectively and considering the mathematical notations of the two algorithms in question; you can see without the involvement of the computer hardware and software Case 2 is approximately 60% faster than Case 1.

When you look at the graphs and charts after these algorithms have been applied to some source code, compiled, optimized, and executed through the OS to perform their operations on a given piece of hardware, you can even see a little more degradation between the differences in these algorithms.

If the Data set is fairly small it may not seem all that bad of a difference at first. However, since Case 1 is about 60 - 70% slower than Case 2 we can look at the growth of this function in terms of the differences in time executions:

DeltaTimeDifference approximately = Loop1(time) - Loop2(time)
Loop1(time) = Loop2(time) + (Loop2(time)*[0.6,0.7]) // approximately
// So when we substitute this back into the difference equation we end up with
DeltaTimeDifference approximately = (Loop2(time) + (Loop2(time)*[0.6,0.7])) - Loop2(time)
// And finally we can simplify this to
DeltaTimeDifference approximately = [0.6,0.7]*Loop2(time)

This approximation is the average difference between these two loops both algorithmically and machine operations involving software optimizations and machine instructions.

When the data set grows linearly, so does the difference in time between the two. Algorithm 1 has more fetches than algorithm 2 which is evident when the Boss has to travel back and forth the maximum distance between A & C for every iteration after the first iteration while algorithm 2 the Boss has to travel to A once and then after being done with A he has to travel a maximum distance only one time when going from A to C.

Trying to have the Boss focusing on doing two similar things at once and juggling them back and forth instead of focusing on similar consecutive tasks is going to make him quite angry by the end of the day since he had to travel and work twice as much. Therefore do not lose the scope of the situation by letting your boss getting into an interpolated bottleneck because the boss's spouse and children wouldn't appreciate it.

Amendment: Software Engineering Design Principles

-- The difference between local Stack and heap allocated computations within iterative for loops and the difference between their usages, their efficiencies, and effectiveness --

The mathematical algorithm that I proposed above mainly applies to loops that perform operations on data that is allocated on the heap.

  • Consecutive Stack Operations:
    • If the loops are performing operations on data locally within a single code block or scope that is within the stack frame it will still sort of apply, but the memory locations are much closer where they are typically sequential and the difference in distance traveled or execution time is almost negligible. Since there are no allocations being done within the heap, the memory isn't scattered, and the memory isn't being fetched through ram. The memory is typically sequential and relative to the stack frame and stack pointer.
  • When consecutive operations are being done on the stack, a modern processor will cache repetitive values and addresses keeping these values within local cache registers. The time of operations or instructions here is on the order of nano-seconds.
  • Consecutive Heap Allocated Operations:
    • When you begin to apply heap allocations and the processor has to fetch the memory addresses on consecutive calls, depending on the architecture of the CPU, the bus controller, and the RAM modules the time of operations or execution can be on the order of micro to milliseconds. In comparison to cached stack operations, these are quite slow.
    • The CPU will have to fetch the memory address from RAM and typically anything across the system bus is slow compared to the internal data paths or data buses within the CPU itself.

So when you are working with data that needs to be on the heap and you are traversing through them in loops, it is more efficient to keep each data set and its corresponding algorithms within its own single loop. You will get better optimizations compared to trying to factor out consecutive loops by putting multiple operations of different data sets that are on the heap into a single loop.

It is okay to do this with data that is on the stack since they are frequently cached, but not for data that has to have its memory address queried every iteration.

This is where software engineering and software architecture design comes into play. It is the ability to know how to organize your data, knowing when to cache your data, knowing when to allocate your data on the heap, knowing how to design and implement your algorithms, and knowing when and where to call them.

You might have the same algorithm that pertains to the same data set, but you might want one implementation design for its stack variant and another for its heap-allocated variant just because of the above issue that is seen from its O(n) complexity of the algorithm when working with the heap.

From what I've noticed over the years, many people do not take this fact into consideration. They will tend to design one algorithm that works on a particular data set and they will use it regardless of the data set being locally cached on the stack or if it was allocated on the heap.

If you want true optimization, yes it might seem like code duplication, but to generalize it would be more efficient to have two variants of the same algorithm. One for stack operations, and the other for heap operations that are performed in iterative loops!

Here's a pseudo example: Two simple structs, one algorithm.

struct A {
    int data;
    A() : data{0}{}
    A(int a) : data{a}{}
struct B {
    int data;
    B() : data{0}{}
    A(int b) : data{b}{}

template<typename T>
void Foo( T& t ) {
    // Do something with t

// Some looping operation: first stack then heap.

// Stack data:
A dataSetA[10] = {};
B dataSetB[10] = {};

// For stack operations this is okay and efficient
for (int i = 0; i < 10; i++ ) {

// If the above two were on the heap then performing
// the same algorithm to both within the same loop
// will create that bottleneck
A* dataSetA = new [] A();
B* dataSetB = new [] B();
for ( int i = 0; i < 10; i++ ) {
    Foo(dataSetA[i]); // dataSetA is on the heap here
    Foo(dataSetB[i]); // dataSetB is on the heap here
} // this will be inefficient.

// To improve the efficiency above, put them into separate loops...

for (int i = 0; i < 10; i++ ) {
for (int i = 0; i < 10; i++ ) {
// This will be much more efficient than above.
// The code isn't perfect syntax, it's only psuedo code
// to illustrate a point.

This is what I was referring to by having separate implementations for stack variants versus heap variants. The algorithms themselves don't matter too much, it's the looping structures that you will use them in that do.

Git commit -a "untracked files"?

For others having the same problem, try running

git add . which will add all files of the current directory to track (including untracked) and then use

git commit -a to commit all tracked files.

As suggested by @Pacerier, one liner that does the same thing is

git add -A

How are SSL certificate server names resolved/Can I add alternative names using keytool?

How host name verification should be done is defined in RFC 6125, which is quite recent and generalises the practice to all protocols, and replaces RFC 2818, which was specific to HTTPS. (I'm not even sure Java 7 uses RFC 6125, which might be too recent for this.)

From RFC 2818 (Section 3.1):

If a subjectAltName extension of type dNSName is present, that MUST be used as the identity. Otherwise, the (most specific) Common Name field in the Subject field of the certificate MUST be used. Although the use of the Common Name is existing practice, it is deprecated and Certification Authorities are encouraged to use the dNSName instead.


In some cases, the URI is specified as an IP address rather than a hostname. In this case, the iPAddress subjectAltName must be present in the certificate and must exactly match the IP in the URI.

Essentially, the specific problem you have comes from the fact that you're using IP addresses in your CN and not a host name. Some browsers might work because not all tools follow this specification strictly, in particular because "most specific" in RFC 2818 isn't clearly defined (see discussions in RFC 6215).

If you're using keytool, as of Java 7, keytool has an option to include a Subject Alternative Name (see the table in the documentation for -ext): you could use -ext or -ext san=ip:


You can request a SAN in OpenSSL by changing openssl.cnf (it will pick the copy in the current directory if you don't want to edit the global configuration, as far as I remember, or you can choose an explicit location using the OPENSSL_CONF environment variable).

Set the following options (find the appropriate sections within brackets first):

req_extensions = v3_req

[ v3_req ]
# or

There's also a nice trick to use an environment variable for this (rather in than fixing it in a configuration file) here:

How to ssh connect through python Paramiko with ppk public key

To create a valid DSA format private key supported by Paramiko in Puttygen.

Click on Conversions then Export OpenSSH Key

enter image description here

How to split a string between letters and digits (or between digits and letters)?

Wouldn't this "d+|D+" do the job instead of the cumbersome: "(?<=\\D)(?=\\d)|(?<=\\d)(?=\\D)" ?

how to remove the bold from a headline?

<h1><span>This is</span> a Headline</h1>

h1 { font-weight: normal; text-transform: uppercase; }
h1 span { font-weight: bold; }

I'm not sure if it was just for the sake of showing us, but as a side note, you should always set uppercase text with CSS :)

Symfony2 Setting a default choice field selection

From the docs:

public Form createNamed(string|FormTypeInterface $type, string $name, mixed $data = null, array $options = array())

mixed $data = null is the default options. So for example I have a field called status and I implemented it as so:

$default = array('Status' => 'pending');

$filter_form = $this->get('form.factory')->createNamedBuilder('filter', 'form', $default)
        ->add('Status', 'choice', array(
            'choices' => array(
                '' => 'Please Select...',
                'rejected' => 'Rejected',
                'incomplete' => 'Incomplete',
                'pending' => 'Pending',
                'approved' => 'Approved',
                'validated' => 'Validated',
                'processed' => 'Processed'

Get column from a two dimensional array

I have created a library matrix-slicer to manipulate with matrix items. So your problem could be solved like this:

var m = new Matrix([
    [1, 2],
    [3, 4],

m.getColumn(1); // => [2, 4]

Possible it will be useful for somebody. ;-)

Is it possible to interactively delete matching search pattern in Vim?

There are 3 ways I can think of:

The way that is easiest to explain is

:%s/phrase to delete//gc

but you can also (personally I use this second one more often) do a regular search for the phrase to delete

/phrase to delete

Vim will take you to the beginning of the next occurrence of the phrase.

Go into insert mode (hit i) and use the Delete key to remove the phrase.

Hit escape when you have deleted all of the phrase.

Now that you have done this one time, you can hit n to go to the next occurrence of the phrase and then hit the dot/period "." key to perform the delete action you just performed

Continue hitting n and dot until you are done.

Lastly you can do a search for the phrase to delete (like in second method) but this time, instead of going into insert mode, you

Count the number of characters you want to delete

Type that number in (with number keys)

Hit the x key - characters should get deleted

Continue through with n and dot like in the second method.

PS - And if you didn't know already you can do a capital n to move backwards through the search matches.

Git keeps prompting me for a password

In my case, I was always getting a password prompt when I tried to cherrypick a URL like below:

git fetch http://username@gerrit-domainname/repositoryname refs/changes/1/12345/1 && git cherry-pick FETCH_HEAD

This URL worked well when cherrypicked on a different machine. However, At my end when I try to cherrypick with correct password abc@12345 I used to get below error:

remote: Unauthorized
remote: Authentication failed for http://username@gerrit-domainname  

In my git config file the remote URL was like below:

url = ssh://gerrit-domainname:8080/wnc

I resolved the authentication failure issue by providing the HTTP Password which I found at
My gerrit account -> Settings -> HTTP Password.

The HTTP Password was something like Th+IsAduMMy+PaSS+WordT+RY+Your+OwNPaSs which was way different than my actual password abc@12345

Note: My URL to cherrpick starts with git fetch ... So, this solution might work on git checkout/download where the URL starts with git fetch ...

Show week number with Javascript?

By adding the snippet you extend the Date object.

Date.prototype.getWeek = function() {
    var onejan = new Date(this.getFullYear(),0,1);
    return Math.ceil((((this - onejan) / 86400000) + onejan.getDay()+1)/7);

If you want to use this in multiple pages you can add this to a seperate js file which must be loaded first before your other scripts executes. With other scripts I mean the scripts which uses the getWeek() method.

Saving ssh key fails

In Windows I had to create the environment variable HOME pointing to my user profile first (C:\Users\<name>) or whatever directory you prefer.

Then start a new command line window, create a a .ssh directory in your user profile or choosen diretory using mkdir ".ssh" command.

After doing that I was able to use the ssh-keygen without any path problems.

Open page in new window without popup blocking

As a general rule, pop up blockers target windows that launch without user interaction. Usually a click event can open a window without it being blocked. (unless it's a really bad popup blocker)

Try launching after a click event

Rename file with Git

You can rename a file using git's mv command:

$ git mv file_from file_to


$ git mv helo.txt hello.txt

$ git status
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#   renamed:    helo.txt -> hello.txt

$ git commit -m "renamed helo.txt to hello.txt"
[master 14c8c4f] renamed helo.txt to hello.txt
 1 files changed, 0 insertions(+), 0 deletions(-)
 rename helo.txt => hello.txt (100%)

jQuery.each - Getting li elements inside an ul

$(function() {
    $('.phrase .items').each(function(i, items_list){
        var myText = "";

        $(items_list).find('li').each(function(j, li){



Search a text file and print related lines in Python?

Note the potential for an out-of-range index with "i+3". You could do something like:

with open("file.txt", "r") as f:
    searchlines = f.readlines()
for i, line in enumerate(searchlines):
    if "searchphrase" in line: 
        for l in searchlines[i:k]: print l,

Edit: maybe not necessary. I just tested some examples. x[y] will give errors if y is out of range, but x[y:z] doesn't seem to give errors for out of range values of y and z.

How do I verify/check/test/validate my SSH passphrase?

If your passphrase is to unlock your SSH key and you don't have ssh-agent, but do have sshd (the SSH daemon) installed on your machine, do:

cat ~/.ssh/ >> ~/.ssh/authorized_keys;
ssh localhost -i ~/.ssh/id_rsa

Where ~/.ssh/ is the public key, and ~/.ssh/id_rsa is the private key.

How to generate an openSSL key using a passphrase from the command line?

genrsa has been replaced by genpkey & when run manually in a terminal it will prompt for a password:

openssl genpkey -aes-256-cbc -algorithm RSA -out /etc/ssl/private/key.pem -pkeyopt rsa_keygen_bits:4096

However when run from a script the command will not ask for a password so to avoid the password being viewable as a process use a function in a shell script:

get_passwd() {
    local passwd=
    echo -ne "Enter passwd for private key: ? "; read -s passwd
    openssl genpkey -aes-256-cbc -pass pass:$passwd -algorithm RSA -out $PRIV_KEY -pkeyopt rsa_keygen_bits:$PRIV_KEYSIZE

Can CSS force a line break after each word in an element?

The best solution is the word-spacing property.

Add the <p> in a container with a specific size (example 300px) and after you have to add that size as the value in the word-spacing.


 <p>Sentence Here</p>


div {
 width: 300px;

p {
 width: auto;
 text-align: center;
 word-spacing: 300px;

In this way, your sentence will be always broken and set in a column, but the with of the paragraph will be dynamic.

Here an example Codepen

Check string for palindrome

also a different looking solution:

public static boolean isPalindrome(String s) {

        for (int i=0 , j=s.length()-1 ; i<j ; i++ , j-- ) {

            if ( s.charAt(i) != s.charAt(j) ) {
                return false;

        return true;

Get Line Number of certain phrase in file Python

suzanshakya, I'm actually modifying your code, I think this will simplify the code, but make sure before running the code the file must be in the same directory of the console otherwise you'll get error.

file_name = open("file.txt")
for num, line in enumerate(file_name,1):
        if lookup in line:

What does string::npos mean in this code?

static const size_t npos = -1;

Maximum value for size_t

npos is a static member constant value with the greatest possible value for an element of type size_t.

This value, when used as the value for a len (or sublen) parameter in string's member functions, means "until the end of the string".

As a return value, it is usually used to indicate no matches.

This constant is defined with a value of -1, which because size_t is an unsigned integral type, it is the largest possible representable value for this type.

Easiest way to read/write a file's content in Python

Slow, ugly, platform-specific... but one-liner ;-)

import subprocess

contents = subprocess.Popen('cat %s' % filename, shell = True, stdout = subprocess.PIPE).communicate()[0]

jQuery: Setting select list 'selected' based on text, failing strangely

If you want to selected value on drop-down text bases so you should use below changes: Here below is example and country name is dynamic:

    <select id="selectcountry">
    <option value="1">India</option>
    <option value="2">Ireland</option>
     var country_name ='India'
     $('#selectcountry').find('option:contains("' + country_name + '")').attr('selected', 'selected');

"Auth Failed" error with EGit and GitHub

On Windows, setting GIT_SSH to openssh that comes with msys git didn't work (Eclipse hung during commit). Setting it to TortoisePlink solved the problem (I guess original plink would work as well). The added bonus is now Eclipse uses keys stored in pageant.

Check list of words in another string

Here are a couple of alternative ways of doing it, that may be faster or more suitable than KennyTM's answer, depending on the context.

1) use a regular expression:

import re
words_re = re.compile("|".join(list_of_words))

if'some one long two phrase three'):
   # do logic you want to perform

2) You could use sets if you want to match whole words, e.g. you do not want to find the word "the" in the phrase "them theorems are theoretical":

word_set = set(list_of_words)
phrase_set = set('some one long two phrase three'.split())
if word_set.intersection(phrase_set):
    # do stuff

Of course you can also do whole word matches with regex using the "\b" token.

The performance of these and Kenny's solution are going to depend on several factors, such as how long the word list and phrase string are, and how often they change. If performance is not an issue then go for the simplest, which is probably Kenny's.

ExecutorService, how to wait for all tasks to finish

I also have the situation that I have a set of documents to be crawled. I start with an initial "seed" document which should be processed, that document contains links to other documents which should also be processed, and so on.

In my main program, I just want to write something like the following, where Crawler controls a bunch of threads.

Crawler c = new Crawler();

The same situation would happen if I wanted to navigate a tree; i would pop in the root node, the processor for each node would add children to the queue as necessary, and a bunch of threads would process all the nodes in the tree, until there were no more.

I couldn't find anything in the JVM which I thought was a bit surprising. So I wrote a class ThreadPool which one can either use directly or subclass to add methods suitable for the domain, e.g. schedule(Document). Hope it helps!

ThreadPool Javadoc | Maven

Possible to view PHP code of a website?

By using exploits or on badly configured servers it could be possible to download your PHP source. You could however either obfuscate and/or encrypt your code (using Zend Guard, Ioncube or a similar app) if you want to make sure your source will not be readable (to be accurate, obfuscation by itself could be reversed given enough time/resources, but I haven't found an IonCube or Zend Guard decryptor yet...).

while ($row = mysql_fetch_array($result)) - how many loops are being performed?

For the first one: your program will go through the loop once for every row in the result set returned by the query. You can know in advance how many results there are by using mysql_num_rows().

For the second one: this time you are only using one row of the result set and you are doing something for each of the columns. That's what the foreach language construct does: it goes through the body of the loop for each entry in the array $row. The number of times the program will go through the loop is knowable in advance: it will go through once for every column in the result set (which presumably you know, but if you need to determine it you can use count($row)).

Python - Locating the position of a regex match in a string?

re.Match objects have a number of methods to help you with this:

>>> m ="is", String)
>>> m.span()
(2, 4)
>>> m.start()
>>> m.end()

How to convert SSH keypairs generated using PuTTYgen (Windows) into key-pairs used by ssh-agent and Keychain (Linux)

PPK ? OpenSSH RSA with PuttyGen & Docker.

Private key:

docker run --rm -v $(pwd):/app zinuzoid/puttygen private.ppk -O private-openssh -o my-openssh-key

Public key:

docker run --rm -v $(pwd):/app zinuzoid/puttygen private.ppk -L -o

See also

How do I write a RGB color value in JavaScript?

dec2hex = function (d) {
  if (d > 15)
    { return d.toString(16) } else
    { return "0" + d.toString(16) }
rgb = function (r, g, b) { return "#" + dec2hex(r) + dec2hex(g) + dec2hex(b) };


parent.childNodes[1].style.color = rgb(155, 102, 102);

What's a quick way to comment/uncomment lines in Vim?

The quickest and the most intuitive method of them all is to remap ) for walk-down-commenting of lines, and then ( for walk-up-uncommenting. Try it and you won't go back.

In Ruby or Bash, with 2-space indents:

map ) I# <Esc>j
map ( k^2x

In C/C++ or PHP, with 4-space indents:

map ) I//  <Esc>j
map ( k^4x

Downsides are that you lose ( and ) for sentence-movement (but das can fill in there), and you'll occasionally fall back on select-and-replace or CtrlV for handling long sections. But that's pretty rare.

And for C-style, the long comments are best handled with:

set cindent
set formatoptions=tcqr

... Which combines well with using V[move]gq to redo the word-wrapping.

Enum Naming Convention - Plural

The situation never really applies to plural.

An enum shows an attribute of something or another. I'll give an example:

enum Humour

You can have one type, but try think of it in the multiple, rather than plural:

Humour.Irony | Humour.Sarcasm

Rather than

Humours { Irony, Sarcasm }

You have a sense of humour, you don't have a sense of humours.

Proper way to handle multiple forms on one page in Django

Wanted to share my solution where Django Forms are not being used. I have multiple form elements on a single page and I want to use a single view to manage all the POST requests from all the forms.

What I've done is I have introduced an invisible input tag so that I can pass a parameter to the views to check which form has been submitted.

<form method="post" id="formOne">
    {% csrf_token %}
   <input type="hidden" name="form_type" value="formOne">



<form method="post" id="formTwo">
    {% csrf_token %}
    <input type="hidden" name="form_type" value="formTwo">

def handlemultipleforms(request, template="handle/multiple_forms.html"):
    Handle Multiple <form></form> elements
    if request.method == 'POST':
        if request.POST.get("form_type") == 'formOne':
            #Handle Elements from first Form
        elif request.POST.get("form_type") == 'formTwo':
            #Handle Elements from second Form

Java Best Practices to Prevent Cross Site Scripting

The normal practice is to HTML-escape any user-controlled data during redisplaying in JSP, not during processing the submitted data in servlet nor during storing in DB. In JSP you can use the JSTL (to install it, just drop jstl-1.2.jar in /WEB-INF/lib) <c:out> tag or fn:escapeXml function for this. E.g.

<%@ taglib uri="" prefix="c" %>
<p>Welcome <c:out value="${}" /></p>


<%@ taglib uri="" prefix="fn" %>
<input name="username" value="${fn:escapeXml(param.username)}">

That's it. No need for a blacklist. Note that user-controlled data covers everything which comes in by a HTTP request: the request parameters, body and headers(!!).

If you HTML-escape it during processing the submitted data and/or storing in DB as well, then it's all spread over the business code and/or in the database. That's only maintenance trouble and you will risk double-escapes or more when you do it at different places (e.g. & would become &amp;amp; instead of &amp; so that the enduser would literally see &amp; instead of & in view. The business code and DB are in turn not sensitive for XSS. Only the view is. You should then escape it only right there in view.

See also:

Unable to Git-push master to Github - 'origin' does not appear to be a git repository / permission denied

One possibility that the above answers don't address is that you may not have an ssh access from your shell. That is, you may be in a network (some college networks do this) where ssh service is blocked.In that case you will not only be able to get github services but also any other ssh services. You can test if this is the problem by trying to use any other ssh service.This was the case with me.

How much overhead does SSL impose?

Assuming you don't count connection set-up (as you indicated in your update), it strongly depends on the cipher chosen. Network overhead (in terms of bandwidth) will be negligible. CPU overhead will be dominated by cryptography. On my mobile Core i5, I can encrypt around 250 MB per second with RC4 on a single core. (RC4 is what you should choose for maximum performance.) AES is slower, providing "only" around 50 MB/s. So, if you choose correct ciphers, you won't manage to keep a single current core busy with the crypto overhead even if you have a fully utilized 1 Gbit line. [Edit: RC4 should not be used because it is no longer secure. However, AES hardware support is now present in many CPUs, which makes AES encryption really fast on such platforms.]

Connection establishment, however, is different. Depending on the implementation (e.g. support for TLS false start), it will add round-trips, which can cause noticable delays. Additionally, expensive crypto takes place on the first connection establishment (above-mentioned CPU could only accept 14 connections per core per second if you foolishly used 4096-bit keys and 100 if you use 2048-bit keys). On subsequent connections, previous sessions are often reused, avoiding the expensive crypto.

So, to summarize:

Transfer on established connection:

  • Delay: nearly none
  • CPU: negligible
  • Bandwidth: negligible

First connection establishment:

  • Delay: additional round-trips
  • Bandwidth: several kilobytes (certificates)
  • CPU on client: medium
  • CPU on server: high

Subsequent connection establishments:

  • Delay: additional round-trip (not sure if one or multiple, may be implementation-dependant)
  • Bandwidth: negligible
  • CPU: nearly none

Regular Expressions: Is there an AND operator?

Is it not possible in your case to do the AND on several matching results? in pseudocode

regexp_match(pattern1, data) && regexp_match(pattern2, data) && ...

Convert a string representation of a hex dump to a byte array using Java?

Here's a solution that I think is better than any posted so far:

/* s must be an even-length string. */
public static byte[] hexStringToByteArray(String s) {
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                             + Character.digit(s.charAt(i+1), 16));
    return data;

Reasons why it is an improvement:

  • Safe with leading zeros (unlike BigInteger) and with negative byte values (unlike Byte.parseByte)

  • Doesn't convert the String into a char[], or create StringBuilder and String objects for every single byte.

  • No library dependencies that may not be available

Feel free to add argument checking via assert or exceptions if the argument is not known to be safe.

How do I remove the passphrase for the SSH key without having to create a new key?

In windows for me it kept saying "id_ed25135: No such file or directory" upon entering above commands. So I went to the folder, copied the path within folder explorer and added "\id_ed25135" at the end.

This is what I ended up typing and worked:
ssh-keygen -p -f C:\Users\john\.ssh\id_ed25135

This worked. Because for some reason, in Cmder the default path was something like this C:\Users\capit/.ssh/id_ed25135 (some were backslashes: "\" and some were forward slashes: "/")

GnuPG: "decryption failed: secret key not available" error from gpg on Windows

Yes, your secret key appears to be missing. Without it, you will not be able to decrypt the files.

Do you have the key backed up somewhere?

Re-creating the keys, whether you use the same passphrase or not, will not work. Each key pair is unique.

How to check if the given string is palindrome?

Using a good data structure usually helps impress the professor:

Push half the chars onto a stack (Length / 2).
Pop and compare each char until the first unmatch.
If the stack has zero elements: palindrome.
*in the case of a string with an odd Length, throw out the middle char.

Visual Studio Code Automatic Imports

VS Code supports this out of the box now, but the feature sometimes works and sometimes doesn't, it seems. As far as I could find out, VS Code has to load data needed for auto imports, which happens more or less like this:

  • Load data for all exports from your local files
  • Load data for all exports from node_modules/@types
  • Load data for all exports from node_modules/{packageName} only if any of your local files is importing them

This is better described in this comment:

Due to bugs either in VS Code or in specific packages' type declarations, the last two points don't always work. That was my case, I couldn't see react-bootstrap auto imports in a plain Create-React-App. What finally fixed it was manually copying the package folder from node_modules to node_modules/@types and leaving there only the type declaration files, e.g. Button.d.ts. This is not great because if you ever delete node_modules folder it will stop working again. But I prefer this from always having to manually type imports. This was my last resort after trying and failing with these methods:

  • Update VS Code (v. 1.45.1)
  • Install types for your package, e.g. npm install --save @types/react-bootstrap
  • Add jsconfig.json file and play with the settings as other people suggested
  • Try out all the plugins for automatic imports

I hope this helps someone!

javax.servlet.ServletException cannot be resolved to a type in spring web app

I guess this may work, in Eclipse select your project ? then click on project menu bar on top ? goto to properties ? click on Targeted Runtimes ? now you must select a check box next to the server you are using to run current project ? click Apply ? then click OK button. That's it, give a try.

urllib2.HTTPError: HTTP Error 403: Forbidden

By adding a few more headers I was able to get the data:

import urllib2,cookielib

site= ""
hdr = {'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11',
       'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
       'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.3',
       'Accept-Encoding': 'none',
       'Accept-Language': 'en-US,en;q=0.8',
       'Connection': 'keep-alive'}

req = urllib2.Request(site, headers=hdr)

    page = urllib2.urlopen(req)
except urllib2.HTTPError, e:

content =
print content

Actually, it works with just this one additional header:

'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',

What is the functionality of setSoTimeout and how it works?

The JavaDoc explains it very well:

With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

SO_TIMEOUT is the timeout that a read() call will block. If the timeout is reached, a will be thrown. If you want to block forever put this option to zero (the default value), then the read() call will block until at least 1 byte could be read.

What's the difference between [ and [[ in Bash?

In bash, contrary to [, [[ prevents word splitting of variable values.

Create a one to many relationship using SQL Server

  1. Define two tables (example A and B), with their own primary key
  2. Define a column in Table A as having a Foreign key relationship based on the primary key of Table B

This means that Table A can have one or more records relating to a single record in Table B.

If you already have the tables in place, use the ALTER TABLE statement to create the foreign key constraint:

ALTER TABLE A ADD CONSTRAINT fk_b FOREIGN KEY (b_id) references b(id) 
  • fk_b: Name of the foreign key constraint, must be unique to the database
  • b_id: Name of column in Table A you are creating the foreign key relationship on
  • b: Name of table, in this case b
  • id: Name of column in Table B

How do I exit from a function?

Yo can simply google for "exit sub in c#".

Also why would you check every text box if it is empty. You can place requiredfieldvalidator for these text boxes if this is an app and check if(Page.IsValid)

Or another solution is to get not of these conditions:

private void button1_Click(object sender, EventArgs e)
    if (!(textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == ""))
        //do events

And better use String.IsNullOrEmpty:

private void button1_Click(object sender, EventArgs e)
    if (!(String.IsNullOrEmpty(textBox1.Text)
    || String.IsNullOrEmpty(textBox2.Text)
    || String.IsNullOrEmpty(textBox3.Text)))
        //do events

How can I get client information such as OS and browser

You can use browscap-java to get browser's information.

For Example:

UserAgentParser parser = new UserAgentService().loadParser(Arrays.asList(BrowsCapField.BROWSER));
    Capabilities capabilities = parser.parse(user_agent);

    String browser = capabilities.getBrowser();

Converting a date string to a DateTime object using Joda Time library

An simple method :

public static DateTime transfStringToDateTime(String dateParam, Session session) throws NotesException {
    DateTime dateRetour;
    dateRetour = session.createDateTime(dateParam);                 

    return dateRetour;

javascript function wait until another function to finish

Following answer can help in this and other similar situations like synchronous AJAX call -

Working example

  console.log('Finally, I can execute!!!');
  console.log('This is error message.');

function waitForMe(){
    // Returns promise
    console.log('Inside waitForMe');
    return new Promise(function(resolve, reject){
        if(true){ // Try changing to 'false'
                console.log('waitForMe\'s function succeeded');
            }, 2500);
                console.log('waitForMe\'s else block failed');
            }, 2500);

Limit the length of a string with AngularJS

I had a similar problem, here is what i did:

{{ longString | limitTo: 20 }} {{longString.length < 20 ? '' : '...'}}

"This project is incompatible with the current version of Visual Studio"

I had this error and found it was due to the presence an 'Import' XML tag inside the .csproj.user file. Once I removed it, Visual Studio could open the project again.

PHP Redirect to another page after form submit

Once had this issue, thought it reasonable to share how I resolved it;

I think the way to do that in php is to use the header function as:

header ("Location: exampleFile.php");

You could just enclose that header file in an if statement so that it redirects only when a certain condition is met, as in:

if (isset($_POST['submit'])){   header("Location: exampleFile.php")   }

Hope that helps.

POST data with request module on Node.JS

EDIT: You should check out Needle. It does this for you and supports multipart data, and a lot more.

I figured out I was missing a header

var request = require('request');{
  headers: {'content-type' : 'application/x-www-form-urlencoded'},
  url:     'http://localhost/test2.php',
  body:    "mes=heydude"
}, function(error, response, body){

Choosing the default value of an Enum type without having to change values

The default value for an enumeration type is 0:

  • "By default, the first enumerator has the value 0, and the value of each successive enumerator is increased by 1."

  • "The value type enum has the value produced by the expression (E)0, where E is the enum identifier."

You can check the documentation for C# enum here, and the documentation for C# default values table here.

Create an Array of Arraylists

As per Oracle Documentation:

"You cannot create arrays of parameterized types"

Instead, you could do:

ArrayList<ArrayList<Individual>> group = new ArrayList<ArrayList<Individual>>(4);

As suggested by Tom Hawting - tackline, it is even better to do:

List<List<Individual>> group = new ArrayList<List<Individual>>(4);

Creating SVG elements dynamically with javascript inside HTML

To facilitate svg editing you can use an intermediate function:

function getNode(n, v) {
  n = document.createElementNS("", n);
  for (var p in v)
    n.setAttributeNS(null, p, v[p]);
  return n

Now you can write:

svg.appendChild( getNode('rect', { width:200, height:20, fill:'#ff0000' }) );

Example (with an improved getNode function allowing camelcase for property with dash, eg strokeWidth > stroke-width):

function getNode(n, v) {_x000D_
  n = document.createElementNS("", n);_x000D_
  for (var p in v)_x000D_
    n.setAttributeNS(null, p.replace(/[A-Z]/g, function(m, p, o, s) { return "-" + m.toLowerCase(); }), v[p]);_x000D_
  return n_x000D_
var svg = getNode("svg");_x000D_
var r = getNode('rect', { x: 10, y: 10, width: 100, height: 20, fill:'#ff00ff' });_x000D_
var r = getNode('rect', { x: 20, y: 40, width: 100, height: 40, rx: 8, ry: 8, fill: 'pink', stroke:'purple', strokeWidth:7 });_x000D_

Multiline input form field using Bootstrap

I think the problem is that you are using type="text" instead of textarea. What you want is:

<textarea class="span6" rows="3" placeholder="What's up?" required></textarea>

To clarify, a type="text" will always be one row, where-as a textarea can be multiple. Remote host closed connection during handshake during web service communicaiton

I encountered a similar problem with glassfish application server and Oracle JDK/JRE but not in Open JDK/JRE.

When connecting to a SSL domain I always ran into: Remote host closed connection during handshake
Caused by: SSL peer shut down incorrectly

The solution for me was to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files because the server only understood certificates that are not included in Oracle JDK by default, only OpenJDK includes them. After installing everything worked like charme.

JCE 7:

JCE 8:

Upload artifacts to Nexus, without Maven

You can also use the direct deploy method using curl. You don't need a pom for your file for it but it will not be generated as well so if you want one, you will have to upload it separately.

Here is the command:


curl -u nexususername:nexuspassword --upload-file filename.tgz $REPO_URL/content/repositories/$repoId/$groupId/$artefact/$version/$artefact-$version.tgz

Controlling Maven final name of jar artifact

You set the finalName property in the plugin configuration section:


As indicated in the official documentation.


For Maven >= 3

Based on Matthew's comment you can now do it like this:


See bug report/documentation.

How to make this Header/Content/Footer layout using CSS?

Here is how to to that:

The header and footer are 30px height.

The footer is stuck to the bottom of the page.


<div id="header">
<div id="content">
<div id="footer">


#header {
    height: 30px;
#footer {
    height: 30px;
    position: absolute;
    bottom: 0;
body {
    height: 100%;
    margin-bottom: 30px;

Try it on jsfiddle:

Android appcompat v7:23

First you need to download the latest support repository (17 by the time I write this) from internal SDK manager of Android Studio or from the stand alone SDK manager. Then you can add compile '' or any other support library you want to your build.gradle file. (Don't forget the last .0)

Is it possible to make input fields read-only through CSS?

CSS based input text readonly change color of selection:


/**default page CSS:**/
::selection { background: #d1d0c3; color: #393729; }
*::-moz-selection { background: #d1d0c3; color: #393729; }

/**for readonly input**/
input[readonly='readonly']:focus { border-color: #ced4da; box-shadow: none; }
input[readonly='readonly']::selection { background: none; color: #000; }
input[readonly='readonly']::-moz-selection { background: none; color: #000; }


<input type="text" value="12345" id="readCaptch" readonly="readonly" class="form-control" />

live Example:

also you can see why i was done!! (php captcha):

Set a border around a StackPanel.

May be it will helpful:

<Border BorderBrush="Black" BorderThickness="1" HorizontalAlignment="Left" Height="160" Margin="10,55,0,0" VerticalAlignment="Top" Width="492"/>

How to schedule a function to run every hour on Flask?

I've tried using flask instead of a simple apscheduler what you need to install is

pip3 install flask_apscheduler

Below is the sample of my code:

from flask import Flask
from flask_apscheduler import APScheduler

app = Flask(__name__)
scheduler = APScheduler()

def scheduleTask():
    print("This test runs every 3 seconds")

if __name__ == '__main__':
    scheduler.add_job(id = 'Scheduled Task', func=scheduleTask, trigger="interval", seconds=3)

Getting value GET OR POST variable using JavaScript?

The simplest technique:

If your form action attribute is omitted, you can send a form to the same HTML file without actually using a GET HTTP access, just by using onClick on the button used for submitting the form. Then the form fields are in the elements array document.FormName.elements . Each element in that array has a value attribute containing the string the user provided (For INPUT elements). It also has id and name attributes, containing the id and/or name provided in the form child elements.

HTML Tags in Javascript Alert() method

alert() doesn't support HTML, but you have some alternatives to format your message.

You can use Unicode characters as others stated, or you can make use of the ES6 Template literals. For example:

.catch(function (error) {
  const alertMessage = `Error retrieving resource. Please make sure:
    • the resource server is accessible
    • you're logged in

    Error: ${error}`;

Output: enter image description here

As you can see, it maintains the line breaks and spaces that we included in the variable, with no extra characters.

How to convert Set to Array?

if no such option exists, then maybe there is a nice idiomatic one-liner for doing that ? like, using for...of, or similar ?

Indeed, there are several ways to convert a Set to an Array:

using Array.from

let array = Array.from(mySet);

Simply spreading the Set out in an array

let array = [...mySet];

The old fashion way, iterating and pushing to a new array (Sets do have forEach)

let array = [];
mySet.forEach(v => array.push(v));

Previously, using the non-standard, and now deprecated array comprehension syntax:

let array = [v for (v of mySet)];

if...else within JSP or JSTL

The construct for this is:

   <c:when test="${..}">...</c:when> <!-- if condition -->
   <c:when test="${..}">...</c:when> <!-- else if condition -->
   <c:otherwise>...</c:otherwise>    <!-- else condition -->

If the condition isn't expensive, I sometimes prefer to simply use two distinct <c:if tags - it makes it easier to read.

What is the meaning of "int(a[::-1])" in Python?

The notation that is used in


means that for a given string/list/tuple, you can slice the said object using the format

<object_name>[<start_index>, <stop_index>, <step>]

This means that the object is going to slice every "step" index from the given start index, till the stop index (excluding the stop index) and return it to you.

In case the start index or stop index is missing, it takes up the default value as the start index and stop index of the given string/list/tuple. If the step is left blank, then it takes the default value of 1 i.e it goes through each index.


a = '1234'
print a[::2]

would print


Now the indexing here and also the step count, support negative numbers. So, if you give a -1 index, it translates to len(a)-1 index. And if you give -x as the step count, then it would step every x'th value from the start index, till the stop index in the reverse direction. For example

a = '1234'
print a[3:0:-1]

This would return


Note, that it doesn't return 4321 because, the stop index is not included.

Now in your case,


would just reverse a given integer, that is stored in a string, and then convert it back to a string

i.e "1234" -> "4321" -> 4321 -> "4321"

If what you are trying to do is just reverse the given string, then simply a[::-1] would work .

Finding duplicate values in a SQL table

select name, email
, case 
when ROW_NUMBER () over (partition by name, email order by name) > 1 then 'Yes'
else 'No'
end "duplicated ?"
from users

Input Type image submit form value?

Add this


To your tag.

VueJs get url query

You can also get them with pure javascript.

For example:

new URL(location.href).searchParams.get('page')

For this url:, it would return a value of 1

Git fails when pushing commit to github

The Problem to push mostly is because of the size of the files that need to be pushed. I was trying to push some libraries of just size 2 mb, then too the push was giving error of RPC with result 7. The line is of 4 mbps and is working fine. Some subsequent tries to the push got me success. If such error comes, wait for few minutes and keep on trying.

I also found out that there are some RPC failures if the github is down or is getting unstable network at their side.

So keeping up trying after some intervals is the only option!

Replace missing values with column mean

lapply can be used instead of a for loop.

d1[] <- lapply(d1, function(x) ifelse(, mean(x, na.rm = TRUE), x))

This doesn't really have any advantages over the for loop, though maybe it's easier if you have non-numeric columns as well, in which case

d1[sapply(d1, is.numeric)] <- lapply(d1[sapply(d1, is.numeric)], function(x) ifelse(, mean(x, na.rm = TRUE), x))

is almost as easy.

Hex-encoded String to Byte Array

try this:

     String str = "9B7D2C34A366BF890C730641E6CECF6F";
     String[] temp = str.split(",");
     bytesArray = new byte[temp.length];
     int index = 0;
     for (String item: temp) {
     bytesArray[index] = Byte.parseByte(item);

Remove characters except digits from string using Python?

x.translate(None, string.digits)

will delete all digits from string. To delete letters and keep the digits, do this:

x.translate(None, string.letters)

Convert double to BigDecimal and set BigDecimal Precision

You want to try String.format("%f", d), which will print your double in decimal notation. Don't use BigDecimal at all.

Regarding the precision issue: You are first storing 47.48 in the double c, then making a new BigDecimal from that double. The loss of precision is in assigning to c. You could do

BigDecimal b = new BigDecimal("47.48")

to avoid losing any precision.

How can I create an object based on an interface file definition in TypeScript?

Using your interface you can do

class Modal() {
  constructor(public iModal: IModal) {
   //You now have access to all your interface variables using this.iModal object,
   //you don't need to define the properties at all, constructor does it for you.

Android Imagebutton change Image OnClick

That is because imgButton is null. Try this instead:


or much easier to read:

imgButton = (Button) findViewById(;

then in onClick: imgButton.setBackgroundResource(R.drawable.ic_action_search);

How to check if user input is not an int value

try this code [updated]:

Scanner scan = null;
       int range, smallest = 0, input;

         boolean error=false;
        scan = new Scanner(;
        System.out.print("Enter an integer between 1-100:  ");

            if(!scan.hasNextInt()) {
                System.out.println("Invalid input!");                      
         range = scan.nextInt();
            if(range < 1) {
                System.out.println("Invalid input!");
        //do nothing

             for(int ii = 1; ii <= range; ii++) {
            scan = new Scanner(;
            System.out.print("Enter value " + ii + ": ");

            if(!scan.hasNextInt()) {
                System.out.println("Invalid input!"); 

How to get RegistrationID using GCM in android

In response to your first question: Yes, you have to run a server app to send the messages, as well as a client app to receive them.

In response to your second question: Yes, every application needs its own API key. This key is for your server app, not the client.

Best way to store data locally in .NET (C#)

Without knowing what your data looks like, i.e. the complexity, size, etc...XML is easy to maintain and easily accessible. I would NOT use an Access database, and flat files are more difficult to maintain over the long haul, particularly if you are dealing with more than one data field/element in your file.

I deal with large flat-file data feeds in good quantities daily, and even though an extreme example, flat-file data is much more difficult to maintain than the XML data feeds I process.

A simple example of loading XML data into a dataset using C#:

DataSet reportData = new DataSet();


You can also check out LINQ to XML as an option for querying the XML data...


Remove duplicates in the list using linq

An universal extension method:

public static class EnumerableExtensions
    public static IEnumerable<T> DistinctBy<T, TKey>(this IEnumerable<T> enumerable, Func<T, TKey> keySelector)
        return enumerable.GroupBy(keySelector).Select(grp => grp.First());

Example of usage:

var lstDst = lst.DistinctBy(item => item.Key);

Easy way to export multiple data.frame to multiple Excel worksheets

I do it in this way for openxlsx using following function

                  startCol = 1, startRow = 1, colNames = TRUE, rowNames = FALSE)
  if(! file.exists(fname))
    wb = createWorkbook()
   wb <- loadWorkbook(file =fname)
  sheet = addWorksheet(wb, sheetname)

  writeData(wb,sheet,data,startCol = startCol, startRow = startRow, 
          colNames = colNames, rowNames = rowNames)
  saveWorkbook(wb, fname,overwrite = TRUE)

Setting DataContext in XAML in WPF

This code will always fail.

As written, it says: "Look for a property named "Employee" on my DataContext property, and set it to the DataContext property". Clearly that isn't right.

To get your code to work, as is, change your window declaration to:

<Window x:Class="SampleApplication.MainWindow"
    Title="MainWindow" Height="350" Width="525">

This declares a new XAML namespace (local) and sets the DataContext to an instance of the Employee class. This will cause your bindings to display the default data (from your constructor).

However, it is highly unlikely this is actually what you want. Instead, you should have a new class (call it MainViewModel) with an Employee property that you then bind to, like this:

public class MainViewModel
   public Employee MyEmployee { get; set; } //In reality this should utilize INotifyPropertyChanged!

Now your XAML becomes:

<Window x:Class="SampleApplication.MainWindow"
        Title="MainWindow" Height="350" Width="525">
    <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding MyEmployee.EmpID}" />
    <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding MyEmployee.EmpName}" />

Now you can add other properties (of other types, names), etc. For more information, see Implementing the Model-View-ViewModel Pattern

How to use external ".js" files

This is the way to include an external javascript file to you HTML markup.

<script type="text/javascript" src="/js/external-javascript.js"></script>

Where external-javascript.js is the external file to be included. Make sure the path and the file name are correct while you including it.

<a href="javascript:showCountry('countryCode')">countryCode</a>

The above mentioned method is correct for anchor tags and will work perfectly. But for other elements you should specify the event explicitly.


<select name="users" onChange="showUser(this.value)">

Thanks, XmindZ

Default password of mysql in ubuntu server 16.04

In latest version, mySQL uses auth_socket, so to login you've to know about the auto generated user credentials. or if you download binary version, while installation process, you can choose lagacy password.

To install SQL in linux debian versions

sudo apt install mysql-server

to know about the password

sudo cat /etc/mysql/debian.cnf

Now login

mysql -u debian-sys-maint -p

use the password from debian.cnf

How to see available user records:

USE mysql
SELECT User, Host, plugin FROM mysql.user;

Now you can create a new user. Use the below commands:

use mysql;
CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
GRANT ALL ON *.* TO 'username'@'localhost';
flush privileges;

To list the grants for the particular mysql user

SHOW GRANTS FOR 'username'@'localhost';

How to revoke all the grants for the particular mysql user


To delete/remove particular user from user account list

DROP USER 'username'@'localhost';

For more commands:

$ man 1 mysql

Please don't reset the password for root, instead create a new user and grant rights. This is the best practice.

SASS :not selector

I tried re-creating this, and .someclass.notip was being generated for me but .someclass:not(.notip) was not, for as long as I did not have the @mixin tip() defined. Once I had that, it all worked.

$dropdown-width: 100px;
$comp-tip: true;

@mixin tip($pos:right) {


@mixin dropdown-pos($pos:right) {
  &:not(.notip) {
    @if $comp-tip == true{
      @if $pos == right {
        top:$dropdown-width * -0.6;
        background-color: #f00;
        @include tip($pos:$pos);
  &.notip {
    @if $pos == right {
      top: 0;
      left:$dropdown-width * 0.8;
      background-color: #00f;

.someclass { @include dropdown-pos(); }

EDIT: is a good place to debug your SASS because it gives you error messages. Undefined mixin 'tip'. it what I get when I remove @mixin tip($pos:right) { }

HTTP 404 Page Not Found in Web Api hosted in IIS 7.5

I also ran into this problem. I solved the problem by going to the Application Pools > Application Pool Name and changed the .NET Framework from version v.2.0.50727 to v4.0.30319.

Find IP address of directly connected device

Windows 7 has the arp command within it. arp -a should show you the static and dynamic type interfaces connected to your system.

How are POST and GET variables handled in Python?

It somewhat depends on what you use as a CGI framework, but they are available in dictionaries accessible to the program. I'd point you to the docs, but I'm not getting through to right now. But this note on will give you a first pointer. Look at the CGI and URLLIB Python libs for more.


Okay, that link busted. Here's the basic wsgi ref

Is there any way to change input type="date" format?

Since this question was asked quite a few things have happened in the web realm, and one of the most exciting is the landing of web components. Now you can solve this issue elegantly with a custom HTML5 element designed to suit your needs. If you wish to override/change the workings of any html tag just build yours playing with the shadow dom.

The good news is that there’s already a lot of boilerplate available so most likely you won’t need to come up with a solution from scratch. Just check what people are building and get ideas from there.

You can start with a simple (and working) solution like datetime-input for polymer that allows you to use a tag like this one:

 <date-input date="{{date}}" timezone="[[timezone]]"></date-input>

or you can get creative and pop-up complete date-pickers styled as you wish, with the formatting and locales you desire, callbacks, and your long list of options (you’ve got a whole custom API at your disposal!)

Standards-compliant, no hacks.

Double-check the available polyfills, what browsers/versions they support, and if it covers enough % of your user base… It's 2018, so chances are it'll surely cover most of your users.

Hope it helps!

Spring .properties file: get element as an Array

With a Spring Boot one can do the following:


Configuration class

import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

public class Configuration {

    List<String> values = new ArrayList<>();

    public List<String> getValues() {
        return values;


This is needed, without this class or without the values in class it is not working.

Spring Boot Application class

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.List;

public class SpringBootConsoleApplication implements CommandLineRunner {

    private static Logger LOG = LoggerFactory.getLogger(SpringBootConsoleApplication.class);

    // notice #{} is used instead of ${}
    List<String> values;

    public static void main(String[] args) {, args);

    public void run(String... args) {"values: {}", values);


How to export/import PuTTy sessions list?

The answer posted by @m0nhawk doesn't seem to work as I test on a Windows 7 machine. Instead, using the following scripts would export/import the settings of putty:

@echo off
set regfile=putty.reg
pushd %~dp0

reg export HKCU\Software\SimonTatham %regfile% /y



@echo off
pushd %~dp0
set regfile=putty.reg

if exist %regfile% reg import %regfile%


How to install XCODE in windows 7 platform?

X-code is primarily made for OS-X or iPhone development on Mac systems. Versions for Windows are not available. However this might help!

There is no way to get Xcode on Windows; however you can use a different SDK like Corona instead although it will not use Objective-C (I believe it uses Lua). I have however heard that it is horrible to use.


what is this value means 1.845E-07 in excel?

1.84E-07 is the exact value, represented using scientific notation, also known as exponential notation.

1.845E-07 is the same as 0.0000001845. Excel will display a number very close to 0 as 0, unless you modify the formatting of the cell to display more decimals.

C# however will get the actual value from the cell. The ToString method use the e-notation when converting small numbers to a string.

You can specify a format string if you don't want to use the e-notation.

How to get all of the immediate subdirectories in Python

Check "Getting a list of all subdirectories in the current directory".

Here's a Python 3 version:

import os

dir_list = next(os.walk('.'))[1]


$(window).width() not the same as media query

The best cross-browser solution is to use

link: allows for you to programmatically check if the current browser window state matches a media query.

var query ='(min-width: 900px)');
if (query) {
   // the browser window is larger than 900px

Note The browser does not support media queries (e.g. old IE) mq will always return false.

Get a filtered list of files in a directory

Keep it simple:

import os
relevant_path = "[path to folder]"
included_extensions = ['jpg','jpeg', 'bmp', 'png', 'gif']
file_names = [fn for fn in os.listdir(relevant_path)
              if any(fn.endswith(ext) for ext in included_extensions)]

I prefer this form of list comprehensions because it reads well in English.

I read the fourth line as: For each fn in os.listdir for my path, give me only the ones that match any one of my included extensions.

It may be hard for novice python programmers to really get used to using list comprehensions for filtering, and it can have some memory overhead for very large data sets, but for listing a directory and other simple string filtering tasks, list comprehensions lead to more clean documentable code.

The only thing about this design is that it doesn't protect you against making the mistake of passing a string instead of a list. For example if you accidentally convert a string to a list and end up checking against all the characters of a string, you could end up getting a slew of false positives.

But it's better to have a problem that's easy to fix than a solution that's hard to understand.

Why do we need C Unions?

Use a union when you have some function where you return a value that can be different depending on what the function did.

How do I obtain the frequencies of each value in an FFT?

Take a look at my answer here.

Answer to comment:

The FFT actually calculates the cross-correlation of the input signal with sine and cosine functions (basis functions) at a range of equally spaced frequencies. For a given FFT output, there is a corresponding frequency (F) as given by the answer I posted. The real part of the output sample is the cross-correlation of the input signal with cos(2*pi*F*t) and the imaginary part is the cross-correlation of the input signal with sin(2*pi*F*t). The reason the input signal is correlated with sin and cos functions is to account for phase differences between the input signal and basis functions.

By taking the magnitude of the complex FFT output, you get a measure of how well the input signal correlates with sinusoids at a set of frequencies regardless of the input signal phase. If you are just analyzing frequency content of a signal, you will almost always take the magnitude or magnitude squared of the complex output of the FFT.

PHP "php://input" vs $_POST

If post data is malformed, $_POST will not contain anything. Yet, php://input will have the malformed string.

For example there is some ajax applications, that do not form correct post key-value sequence for uploading a file, and just dump all the file as post data, without variable names or anything. $_POST will be empty, $_FILES empty also, and php://input will contain exact file, written as a string.

What is the difference between MOV and LEA?

None of the previous answers quite got to the bottom of my own confusion, so I'd like to add my own.

What I was missing is that lea operations treat the use of parentheses different than how mov does.

Think of C. Let's say I have an array of long that I call array. Now the expression array[i] performs a dereference, loading the value from memory at the address array + i * sizeof(long) [1].

On the other hand, consider the expression &array[i]. This still contains the sub-expression array[i], but no dereferencing is performed! The meaning of array[i] has changed. It no longer means to perform a deference but instead acts as a kind of a specification, telling & what memory address we're looking for. If you like, you could alternatively think of the & as "cancelling out" the dereference.

Because the two use-cases are similar in many ways, they share the syntax array[i], but the existence or absence of a & changes how that syntax is interpreted. Without &, it's a dereference and actually reads from the array. With &, it's not. The value array + i * sizeof(long) is still calculated, but it is not dereferenced.

The situation is very similar with mov and lea. With mov, a dereference occurs that does not happen with lea. This is despite the use of parentheses that occurs in both. For instance, movq (%r8), %r9 and leaq (%r8), %r9. With mov, these parentheses mean "dereference"; with lea, they don't. This is similar to how array[i] only means "dereference" when there is no &.

An example is in order.

Consider the code

movq (%rdi, %rsi, 8), %rbp

This loads the value at the memory location %rdi + %rsi * 8 into the register %rbp. That is: get the value in the register %rdi and the value in the register %rsi. Multiply the latter by 8, and then add it to the former. Find the value at this location and place it into the register %rbp.

This code corresponds to the C line x = array[i];, where array becomes %rdi and i becomes %rsi and x becomes %rbp. The 8 is the length of the data type contained in the array.

Now consider similar code that uses lea:

leaq (%rdi, %rsi, 8), %rbp

Just as the use of movq corresponded to dereferencing, the use of leaq here corresponds to not dereferencing. This line of assembly corresponds to the C line x = &array[i];. Recall that & changes the meaning of array[i] from dereferencing to simply specifying a location. Likewise, the use of leaq changes the meaning of (%rdi, %rsi, 8) from dereferencing to specifying a location.

The semantics of this line of code are as follows: get the value in the register %rdi and the value in the register %rsi. Multiply the latter by 8, and then add it to the former. Place this value into the register %rbp. No load from memory is involved, just arithmetic operations [2].

Note that the only difference between my descriptions of leaq and movq is that movq does a dereference, and leaq doesn't. In fact, to write the leaq description, I basically copy+pasted the description of movq, and then removed "Find the value at this location".

To summarize: movq vs. leaq is tricky because they treat the use of parentheses, as in (%rsi) and (%rdi, %rsi, 8), differently. In movq (and all other instruction except lea), these parentheses denote a genuine dereference, whereas in leaq they do not and are purely convenient syntax.

[1] I've said that when array is an array of long, the expression array[i] loads the value from the address array + i * sizeof(long). This is true, but there's a subtlety that should be addressed. If I write the C code

long x = array[5];

this is not the same as typing

long x = *(array + 5 * sizeof(long));

It seems that it should be based on my previous statements, but it's not.

What's going on is that C pointer addition has a trick to it. Say I have a pointer p pointing to values of type T. The expression p + i does not mean "the position at p plus i bytes". Instead, the expression p + i actually means "the position at p plus i * sizeof(T) bytes".

The convenience of this is that to get "the next value" we just have to write p + 1 instead of p + 1 * sizeof(T).

This means that the C code long x = array[5]; is actually equivalent to

long x = *(array + 5)

because C will automatically multiply the 5 by sizeof(long).

So in the context of this StackOverflow question, how is this all relevant? It means that when I say "the address array + i * sizeof(long)", I do not mean for "array + i * sizeof(long)" to be interpreted as a C expression. I am doing the multiplication by sizeof(long) myself in order to make my answer more explicit, but understand that due to that, this expression should not be read as C. Just as normal math that uses C syntax.

[2] Side note: because all lea does is arithmetic operations, its arguments don't actually have to refer to valid addresses. For this reason, it's often used to perform pure arithmetic on values that may not be intended to be dereferenced. For instance, cc with -O2 optimization translates

long f(long x) {
  return x * 5;

into the following (irrelevant lines removed):

  leaq (%rdi, %rdi, 4), %rax  # set %rax to %rdi + %rdi * 4

React JS Error: is not defined react/jsx-no-undef

its very similar with nodejs

var User= require('./Users');

in this case its React:

import User from './User'

right now you can use

return (

Reverse each individual word of "Hello World" string with Java

String someString = new String("Love thy neighbor");
    char[] someChar = someString.toCharArray();
    int j = someChar.length - 1;
    char temp;
    for (int i = 0; i <= someChar.length / 2; i++) {
        temp = someChar[i];
        someChar[i] = someChar[j];
        someChar[j] = temp;
    someString = new String(someChar);


Love thy neighbor
robhgien yht evoL

How can I reuse a navigation bar on multiple pages?

I know this is a quite old question, but when you have JavaScript available you could use jQuery and its AJAX methods.

First, create a page with all the navigation bar's HTML content.

Next, use jQuery's $.get method to fetch the content of the page. For example, let's say you've put all the navigation bar's HTML into a file called navigation.html and added a placeholder tag (Like <div id="nav-placeholder">) in your index.html, then you would use the following code:

<script src="//"></script>
$.get("navigation.html", function(data){

Why are you not able to declare a class as static in Java?

I think this is possible as easy as drink a glass of coffee!. Just take a look at this. We do not use static keyword explicitly while defining class.

public class StaticClass {

    static private int me = 3;
    public static void printHelloWorld() {
       System.out.println("Hello World");

    public static void main(String[] args) {

Is not that a definition of static class? We just use a function binded to just a class. Be careful that in this case we can use another class in that nested. Look at this:

class StaticClass1 {

    public static int yum = 4;

    static void  printHowAreYou() {
        System.out.println("How are you?");

public class StaticClass {

    static int me = 3; 
    public static void printHelloWorld() {
       System.out.println("Hello World");

    public static void main(String[] args) {

PreparedStatement setNull(..)

preparedStatement.setNull(index, java.sql.Types.NULL);

that should work for any type. Though in some cases failure happens on the server-side, like: for SQL:


Oracle 18XE fails with the wrong type: expected DATE, got STRING -- that is a perfectly valid failure;

Bottom line: it is good to know the type if you call .setNull()

How to add/subtract dates with JavaScript?

The way I like, is if you have a date object you can subtract another date object from it to get the difference. Date objects are based on milliseconds from a certain date.

var date1 = new Date(2015, 02, 18); // "18/03/2015", month is 0-index
var date2 = new Date(2015, 02, 20); // "20/03/2015"

var msDiff = date2 - date1; // 172800000, this is time in milliseconds
var daysDiff = msDiff / 1000 / 60 / 60 / 24; // 2 days

So this is how you subtract dates. Now if you want to add them? date1 + date2 gives an error.. But if I want to get the time in ms I can use:

var dateMs = date1 - 0;
// say I want to add 5 days I can use
var days = 5;
var msToAdd = days * 24 * 60 * 60 * 1000; 
var newDate = new Date(dateMs + msToAdd);

By subtracting 0 you turn the date object into the milliseconds format.

How to check programmatically if an application is installed or not in Android?

@Egemen Hamutçu s answer in kotlin B-)

    private fun isAppInstalled(context: Context, uri: String): Boolean {
        val packageInfoList = context.packageManager.getInstalledPackages(PackageManager.GET_ACTIVITIES)
        return packageInfoList.asSequence().filter { it?.packageName == uri }.any()

&& (AND) and || (OR) in IF statements

No it will not be checked. This behaviour is called short-circuit evaluation and is a feature in many languages including Java.

How to reference a local XML Schema file correctly?

Add one more slash after file:// in the value of xsi:schemaLocation. (You have two; you need three. Think protocol://host/path where protocol is 'file' and host is empty here, yielding three slashes in a row.) You can also eliminate the double slashes along the path. I believe that the double slashes help with file systems that allow spaces in file and directory names, but you wisely avoided that complication in your path naming.

xsi:schemaLocation=" file:///C:/environment/workspace/maven-ws/ProjextXmlSchema/email.xsd"

Still not working? I suggest that you carefully copy the full file specification for the XSD into the address bar of Chrome or Firefox:


If the XSD does not display in the browser, delete all but the last component of the path (email.xsd) and see if you can't display the parent directory. Continue in this manner, walking up the directory structure until you discover where the path diverges from the reality of your local filesystem.

If the XSD does displayed in the browser, state what XML processor you're using, and be prepared to hear that it's broken or that you must work around some limitation. I can tell you that the above fix will work with my Xerces-J-based validator.

Oracle SQL Developer - tables cannot be seen

For me, this wound up being a permissions issue.

I solved the problem by creating a superuser role (CREATE ROLE root WITH SUPERUSER LOGIN PASSWORD 'XXXXX';) and then using that superuser account to connect to the database.

This obviously won't be a viable solution in all situations.

Resetting MySQL Root Password with XAMPP on Localhost

Open the file C:\xampp\phpMyAdmin\ in your text editor. Search for the tags below and edit accordingly

$cfg['Servers'][$i]['auth_type'] = 'cookie';
$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = 'password';
$cfg['Servers'][$i]['extension'] = 'mysqli';
$cfg['Servers'][$i]['AllowNoPassword'] = true;

Where 'password' is your new password. In-between quotes.

GO to your browser and visit link http://localhost/phpmyadmin/. Click on 'GO' without your new password. It would log you in and you would be able to see the "CHANGE PASSWORD". Proceed to change your password and you are done.

How can I convert a VBScript to an executable (EXE) file?

More info

To find a compiler, you'll have 1 per .net version installed, type in a command prompt.

dir c:\Windows\Microsoft.NET\vbc.exe /a/s

Windows Forms

For a Windows Forms version (no console window and we don't get around to actually creating any forms - though you can if you want).

Compile line in a command prompt.

"C:\Windows\Microsoft.NET\Framework\v4.0.30319\vbc.exe" /t:winexe "%userprofile%\desktop\VBS2Exe.vb"

Text for VBS2EXE.vb

Imports System.Windows.Forms 

Partial Class MyForm : Inherits Form 

Private Sub InitializeComponent() 

End Sub

Public Sub New() 


End Sub

Public Shared Sub Main() 

Dim sc as object 
Dim Scrpt as string

sc = createObject("MSScriptControl.ScriptControl")

Scrpt = "msgbox " & chr(34) & "Hi there I'm a form" & chr(34)

With SC 
.Language = "VBScript" 
.UseSafeSubset = False 
.AllowUI = True 
End With


End Sub

End Class

Using these optional parameters gives you an icon and manifest. A manifest allows you to specify run as normal, run elevated if admin, only run elevated.

/win32icon: Specifies a Win32 icon file (.ico) for the default Win32 resources.

/win32manifest: The provided file is embedded in the manifest section of the output PE.

In theory, I have UAC off so can't test, but put this text file on the desktop and call it vbs2exe.manifest, save as UTF-8.

The command line

"C:\Windows\Microsoft.NET\Framework\v4.0.30319\vbc.exe" /t:winexe /win32manifest:"%userprofile%\desktop\VBS2Exe.manifest" "%userprofile%\desktop\VBS2Exe.vb"

The manifest

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> 
  <assembly xmlns="urn:schemas-microsoft-com:asm.v1" 
  manifestVersion="1.0"> <assemblyIdentity version="" 
  processorArchitecture="*" name="VBS2EXE" type="win32" /> 
  <description>Script to Exe</description> 
  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3"> 
  <security> <requestedPrivileges> 
  <requestedExecutionLevel level="requireAdministrator" 
  uiAccess="false" /> </requestedPrivileges> 
  </security> </trustInfo> </assembly>

Hopefully it will now ONLY run as admin.

Give Access To a Host's Objects

Here's an example giving the vbscript access to a .NET object.

Imports System.Windows.Forms 

Partial Class MyForm : Inherits Form 

Private Sub InitializeComponent() 

End Sub 

Public Sub New() 


End Sub 

Public Shared Sub Main() 

Dim sc as object
Dim Scrpt as string 

sc = createObject("MSScriptControl.ScriptControl") 

Scrpt = "msgbox " & chr(34) & "Hi there I'm a form" & chr(34) & ":msgbox meScript.state" 

With SC
.Language = "VBScript"
.UseSafeSubset = False
.AllowUI = True
.addobject("meScript", SC, true)
End With 


End Sub 

End Class 

To Embed version info

Download vbs2exe.res file from!121 and put on desktop.

Download ResHacker from

Open vbs2exe.res file in ResHacker. Edit away. Click Compile button. Click File menu - Save.


"C:\Windows\Microsoft.NET\Framework\v4.0.30319\vbc.exe" /t:winexe /win32manifest:"%userprofile%\desktop\VBS2Exe.manifest" /win32resource:"%userprofile%\desktop\VBS2Exe.res" "%userprofile%\desktop\VBS2Exe.vb"

How can I convert an Int to a CString?

If you want something more similar to your example try _itot_s. On Microsoft compilers _itot_s points to _itoa_s or _itow_s depending on your Unicode setting:

CString str;
_itot_s( 15, str.GetBufferSetLength( 40 ), 40, 10 );

it should be slightly faster since it doesn't need to parse an input format.

How can I return pivot table output in MySQL?

There is a tool called MySQL Pivot table generator, it can help you create web based pivot table that you can later export to excel(if you like). it can work if your data is in a single table or in several tables .

All you need to do is to specify the data source of the columns (it supports dynamic columns), rows , the values in the body of the table and table relationship (if there are any) MySQL Pivot Table

The home page of this tool is

In Java, how do I check if a string contains a substring (ignoring case)?

I'd use a combination of the contains method and the toUpper method that are part of the String class. An example is below:

String string1 = "AAABBBCCC"; 
String string2 = "DDDEEEFFF";
String searchForThis = "AABB";



This will return:


Solving "DLL load failed: %1 is not a valid Win32 application." for Pygame

Looks like the question has been long ago answered but the solution did not work for me. When I was getting that error, I was able to fix the problem by downloading PyWin32

command to remove row from a data frame

eldNew <- eld[-14,]

See ?"[" for a start ...

For ‘[’-indexing only: ‘i’, ‘j’, ‘...’ can be logical vectors, indicating elements/slices to select. Such vectors are recycled if necessary to match the corresponding extent. ‘i’, ‘j’, ‘...’ can also be negative integers, indicating elements/slices to leave out of the selection.

(emphasis added)

edit: looking around I notice How to delete the first row of a dataframe in R? , which has the answer ... seems like the title should have popped to your attention if you were looking for answers on SO?

edit 2: I also found How do I delete rows in a data frame? , searching SO for delete row data frame ...


Compression/Decompression string with C#

For those who still getting The magic number in GZip header is not correct. Make sure you are passing in a GZip stream. ERROR and if your string was zipped using php you'll need to do something like:

       public static string decodeDecompress(string originalReceivedSrc) {
        byte[] bytes = Convert.FromBase64String(originalReceivedSrc);

        using (var mem = new MemoryStream()) {
            //the trick is here
            mem.Write(new byte[] { 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00 }, 0, 8);
            mem.Write(bytes, 0, bytes.Length);

            mem.Position = 0;

            using (var gzip = new GZipStream(mem, CompressionMode.Decompress))
            using (var reader = new StreamReader(gzip)) {
                return reader.ReadToEnd();

Android emulator not able to access the internet

I am on android studio 3.1 and it happened. Solved it by restarting the adb server

$ adb kill-server
$ adb start-server

Hope it helps. Thank you

Setting selected option in laravel form

Setting selected option is very simple in laravel form :

{{ Form::select('number', [0, 1, 2], 2) }}

Output will be :

<select name="number">
  <option value="0">0</option>
  <option value="1">1</option>
  <option value="2" selected="selected">2</option>

WebView showing ERR_CLEARTEXT_NOT_PERMITTED although site is HTTPS


Add the below line in your application tag:


As shown below:


UPDATE: If you have network security config such as: android:networkSecurityConfig="@xml/network_security_config"

No Need to set clear text traffic to true as shown above, instead use the below code:

<?xml version="1.0" encoding="utf-8"?>
    <domain-config cleartextTrafficPermitted="true">

    <base-config cleartextTrafficPermitted="false"/>

Set the cleartextTrafficPermitted to true

Hope it helps.

Creating a UITableView Programmatically

#import "ViewController.h"

@interface ViewController ()


    NSMutableArray *name;



- (void)viewDidLoad 


    [super viewDidLoad];
    name=[[NSMutableArray alloc]init];
    [name addObject:@"ronak"];
    [name addObject:@"vibha"];
    [name addObject:@"shivani"];
    [name addObject:@"nidhi"];
    [name addObject:@"firdosh"];
    [name addObject:@"himani"];

    _tableview_outlet.delegate = self;
    _tableview_outlet.dataSource = self;


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section


return [name count];


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath


    static NSString *simpleTableIdentifier = @"cell";

    UITableViewCell *cell = [tableView       dequeueReusableCellWithIdentifier:simpleTableIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:simpleTableIdentifier];

    cell.textLabel.text = [name objectAtIndex:indexPath.row];
    return cell;

Detect if an element is visible with jQuery

You're looking for:


Although you should probably change your selector to use jQuery considering you're using it in other places anyway:

if($('#testElement').is(':visible')) {
    // Code

It is important to note that if any one of a target element's parent elements are hidden, then .is(':visible') on the child will return false (which makes sense).

jQuery 3

:visible has had a reputation for being quite a slow selector as it has to traverse up the DOM tree inspecting a bunch of elements. There's good news for jQuery 3, however, as this post explains (Ctrl + F for :visible):

Thanks to some detective work by Paul Irish at Google, we identified some cases where we could skip a bunch of extra work when custom selectors like :visible are used many times in the same document. That particular case is up to 17 times faster now!

Keep in mind that even with this improvement, selectors like :visible and :hidden can be expensive because they depend on the browser to determine whether elements are actually displaying on the page. That may require, in the worst case, a complete recalculation of CSS styles and page layout! While we don’t discourage their use in most cases, we recommend testing your pages to determine if these selectors are causing performance issues.

Expanding even further to your specific use case, there is a built in jQuery function called $.fadeToggle():

function toggleTestElement() {

Error when using scp command "bash: scp: command not found"

Make sure the scp command is available on both sides - both on the client and on the server.

If this is Fedora or Red Hat Enterprise Linux and clones (CentOS), make sure this package is installed:

    yum -y install openssh-clients

If you work with Debian or Ubuntu and clones, install this package:

    apt-get install openssh-client

Again, you need to do this both on the server and the client, otherwise you can encounter "weird" error messages on your client: scp: command not found or similar although you have it locally. This already confused thousands of people, I guess :)

Unbalanced calls to begin/end appearance transitions for <UITabBarController: 0x197870>

I had the same error. I have a tab bar with 3 items and I was unconsciously trying to call the root view controller of item 1 in the item 2 of my tab bar using performSegueWithIdentifier.

What happens is that it calls the view controller and goes back to the root view controller of item 2 after a few seconds and logs that error.

Apparently, you cannot call the root view controller of an item to another item.

So instead of performSegueWithIdentifier

I used [self.parentViewController.tabBarController setSelectedIndex:0];

Hope this helps someone.

How to change legend size with matplotlib.pyplot

There are also a few named fontsizes, apart from the size in points:



pyplot.legend(loc=2, fontsize = 'x-small')

How to send string from one activity to another?

You can send data from one actvity to another with an Intent

Intent sendStuff = new Intent(this, TargetActivity.class);
sendStuff.putExtra(key, stringvalue);

You then can retrieve this information in the second activity by getting the intent and extracting the string extra. Do this in your onCreate() method.

Intent startingIntent = getIntent();
String whatYouSent = startingIntent.getStringExtra(key, value);

Then all you have to do is call setText on your TextView and use that string.

List files recursively in Linux CLI with path relative to the current directory

To get the actual full path file names of the desired files using the find command, use it with the pwd command:

find $(pwd) -name \*.txt -print

How to test if list element exists?

A slight modified version of @salient.salamander , if one wants to check on full path, this can be used.

Element_Exists_Check = function( full_index_path ){
    len_element = length(full_index_path)
    exists_indicator = ifelse(len_element > 0, T, F)
  }, error = function(e) {

Init method in Spring Controller (annotation version)

public class InitHelloWorld implements BeanPostProcessor {

   public Object postProcessBeforeInitialization(Object bean,
             String beanName) throws BeansException {
       System.out.println("BeforeInitialization : " + beanName);
       return bean;  // you can return any other object as well

   public Object postProcessAfterInitialization(Object bean,
             String beanName) throws BeansException {
       System.out.println("AfterInitialization : " + beanName);
       return bean;  // you can return any other object as well


How to completely remove node.js from Windows

I had the same problem with me yesterday and my solution is: 1. uninstall from controlpanel not from your cli 2. download and install the latest or desired version of node from its website 3. if by mistake you tried uninstalling through cli (it will not remove completely most often) then you do not get uninstall option in cpanel in this case install the same version of node and then follow my 1. step

Hope it helps someone.

Python calling method in class

Could someone explain to me, how to call the move method with the variable RIGHT

>>> myMissile = MissileDevice(myBattery)  # looks like you need a battery, don't know what that is, you figure it out.
>>> myMissile.move(MissileDevice.RIGHT)

If you have programmed in any other language with classes, besides python, this sort of thing

class Foo:
    bar = "baz"

is probably unfamiliar. In python, the class is a factory for objects, but it is itself an object; and variables defined in its scope are attached to the class, not the instances returned by the class. to refer to bar, above, you can just call it; you can also access class attributes through instances of the class, like Foo().bar.

Im utterly baffled about what 'self' refers too,

>>> class Foo:
...     def quux(self):
...         print self
...         print
...     bar = 'baz'
>>> Foo.quux
<unbound method Foo.quux>
>>> f = Foo()
>>> f
<__main__.Foo instance at 0x0286A058>
>>> f.quux
<bound method Foo.quux of <__main__.Foo instance at 0x0286A058>>
>>> f.quux()
<__main__.Foo instance at 0x0286A058>

When you acecss an attribute on a python object, the interpreter will notice, when the looked up attribute was on the class, and is a function, that it should return a "bound" method instead of the function itself. All this does is arrange for the instance to be passed as the first argument.

How do I request a file but not save it with Wget?

Curl does that by default without any parameters or flags, I would use it for your purposes:

curl $url > /dev/null 2>&1

Curl is more about streams and wget is more about copying sites based on this comparison.

Sorting objects by property values

I have wrote this simple function for myself:

function sortObj(list, key) {
    function compare(a, b) {
        a = a[key];
        b = b[key];
        var type = (typeof(a) === 'string' ||
                    typeof(b) === 'string') ? 'string' : 'number';
        var result;
        if (type === 'string') result = a.localeCompare(b);
        else result = a - b;
        return result;
    return list.sort(compare);

for example you have list of cars:

var cars= [{brand: 'audi', speed: 240}, {brand: 'fiat', speed: 190}];
var carsSortedByBrand = sortObj(cars, 'brand');
var carsSortedBySpeed = sortObj(cars, 'speed');

How to wait for the 'end' of 'resize' event and only then perform an action?

this worked for me as I did not want to use any plugins.

$(window).resize(function() {
    var originalWindowSize = 0;
    var currentWidth = 0;

    var setFn = function () {
        originalWindowSize = $(window).width();

    var checkFn = function () {
        setTimeout(function () {
            currentWidth = $(window).width();
            if (currentWidth === originalWindowSize) {
      "same? = yes") 
                // execute code 
            } else {
      "same? = no"); 
                // do nothing 
        }, 500)

On window re-size invoke "setFn" which gets width of window and save as "originalWindowSize". Then invoke "checkFn" which after 500ms (or your preference) gets the current window size, and compares the original to the current, if they are not the same, then the window is still being re-sized. Don't forget to remove console messages in production, and (optional) can make "setFn" self executing.

How to select a node of treeview programmatically in c#?

private void btn_CollapseAllAndExpandFirstLevelUnderRoot(object sender, EventArgs e)

    //this example collapses everything, then expands the first level under the root node.

    TreeNode tn =  tv_myTreeView.Nodes[0];

IntelliJ show JavaDocs tooltip on mouse over

In IntelliJ IDEA 14, it has moved to: File -> Settings -> Editor -> General -> "Show quick doc on mouse move"

submitting a GET form with query string params and hidden params disappear

You should include the two items (a and b) as hidden input elements as well as C.

Set output of a command as a variable (with pipes)

The lack of a Linux-like backtick/backquote facility is a major annoyance of the pre-PowerShell world. Using backquotes via for-loops is not at all cosy. So we need kinda of setvar myvar cmd-line command.

In my %path% I have a dir with a number of bins and batches to cope with those Win shortcomings.

One batch I wrote is:

:: setvar varname cmd
:: Set VARNAME to the output of CMD
:: Triple escape pipes, eg:
:: setvar x  dir c:\ ^^^| sort 
:: -----------------------------

@echo off

:: Get command from argument 
for /F "tokens=1,*" %%a in ("%*") do set cmd=%%b

:: Get output and set var
for /F "usebackq delims=" %%a in (`%cmd%`) do (
     set %1=%%a

:: Show results 
SETLOCAL EnableDelayedExpansion
echo %1=!%1! 

So in your case, you would type:

> setvar text echo Hello

The script informs you of the results, which means you can:

> echo text var is now %text%
text var is now Hello 

You can use whatever command:

> setvar text FIND "Jones" names.txt

What if the command you want to pipe to some variable contains itself a pipe?
Triple escape it, ^^^|:

> setvar text dir c:\ ^^^| find "Win"

Problem in running .net framework 4.0 website on iis 7.0

  1. Go to the IIS Manager.
  2. open the server name like (PC-Name)\.
  3. then double click on the ISAPI and CGI Restriction.
  4. then select ASP.NET v4.0.30319(32-bit) Restriction allowed.

How to break out of the IF statement

just want to add another variant to update this wonderful "how to" list. Though, It may be really useful in more complicated cases:

try {
    if (something)
        //some code
        if (something2)
            throw new Exception("Weird-01.");
            // now You will go to the catch statement
        if (something3)
            throw new Exception("Weird-02.");
            // now You will go to the catch statement
        //some code
catch (Exception ex)
    Console.WriteLine(ex); // you will get your Weird-01 or Weird-02 here
// The code i want to go if the second or third if is true

org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/CollegeWebsite]]

You have a version conflict, please verify whether compiled version and JVM of Tomcat version are same. you can do it by examining tomcat startup .bat , looking for JAVA_HOME

How to get first and last day of the current week in JavaScript

SetDate will sets the day of the month. Using setDate during start and end of the month,will result in wrong week

var curr = new Date("08-Jul-2014"); // get current date
var first = curr.getDate() - curr.getDay(); // First day is the day of the month - the day of the week
var last = first + 6; // last day is the first day + 6
var firstday = new Date(curr.setDate(first)); // 06-Jul-2014
var lastday = new Date(curr.setDate(last)); //12-Jul-2014

If u setting Date is 01-Jul-2014, it will show firstday as 29-Jun-2014 and lastday as 05-Jun-2014 instead of 05-Jul-2014

So overcome this issue i used

var curr = new Date();
day = curr.getDay();
firstday = new Date(curr.getTime() - 60*60*24* day*1000); //will return firstday (ie sunday) of the week
lastday = new Date(curr.getTime() + 60 * 60 *24 * 6 * 1000); //adding (60*60*6*24*1000) means adding six days to the firstday which results in lastday (saturday) of the week

MySQL Check if username and password matches in Database

1.) Storage of database passwords Use some kind of hash with a salt and then alter the hash, obfuscate it, for example add a distinct value for each byte. That way your passwords a super secured against dictionary attacks and rainbow tables.

2.) To check if the password matches, create your hash for the password the user put in. Then perform a query against the database for the username and just check if the two password hashes are identical. If they are, give the user an authentication token.

The query should then look like this:

select hashedPassword from users where username=?

Then compare the password to the input.

Further questions?

How to replace special characters in a string?

Replace any special characters by

replaceAll("\\your special character","new character");

ex:to replace all the occurrence of * with white space


*this statement can only replace one type of special character at a time

Execution Failed for task :app:compileDebugJavaWithJavac in Android Studio

I had this issue on Mac OS Sierra on my way to running a React Native Android App for the first time:

Execution failed for task ':app:compileDebugJavaWithJavac'.

> Could not find tools.jar

I changed my JAVA HOME environment variable for Java Development Kit (JDK) from:

export JAVA_HOME='/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home'

to :

export JAVA_HOME='/Applications/Android'

I figured out where the correct version was after creating a project in Android Studio and looking for the JDK location in the project settings.

How can I make setInterval also work when a tab is inactive in Chrome?

It is quite old question but I encountered the same issue.
If you run your web on chrome, you could read through this post Background Tabs in Chrome 57 .

Basically the interval timer could run if it haven't run out of the timer budget.
The consumption of budget is based on CPU time usage of the task inside timer.
Based on my scenario, I draw video to canvas and transport to WebRTC.
The webrtc video connection would keep updating even the tab is inactive.

However you have to use setInterval instead of requestAnimationFrame.
it is not recommended for UI rendering though.

It would be better to listen visibilityChange event and change render mechenism accordingly.

Besides, you could try @kaan-soral and it should works based on the documentation.

Find if current time falls in a time range

You're very close, the problem is you're comparing a DateTime to a TimeOfDay. What you need to do is add the .TimeOfDay property to the end of your Convert.ToDateTime() functions.

Specify an SSH key for git push for a given domain

You can utilize git environment variable GIT_SSH_COMMAND. Run this in your terminal under your git repository:

GIT_SSH_COMMAND='ssh -i ~/.ssh/your_private_key' git submodule update --init

Replace ~/.ssh/your_private_key with the path of ssh private key you wanna use. And you can change the subsequent git command (in the example is git submodule update --init) to others like git pull, git fetch, etc.

What is difference between mutable and immutable String in java

What is difference between mutable and immutable String in java

immutable exist, mutable don't.

how to load CSS file into jsp

You can write like that. This is for whenever you change context path you don't need to modify your jsp file.

<link rel="stylesheet" href="${pageContext.request.contextPath}/css/styles.css" />

MySQL duplicate entry error even though there is no duplicate entry

For me a noop on table has been enough (was already InnoDB):


jQuery count number of divs with a certain class?

And for the plain js answer if anyone might be interested;

var count = document.getElementsByClassName("item");



How does HTTP_USER_AGENT work?

Visit that page, it'll give you a good explanation of each element of your user agent.


MozillaProductSlice. Claims to be a Mozilla based user agent, which is only true for Gecko browsers like Firefox and Netscape. For all other user agents it means 'Mozilla-compatible'. In modern browsers, this is only used for historical reasons. It has no real meaning anymore

How to access shared folder without giving username and password

You need to go to user accounts and enable Guest Account, its default disabled. Once you do this, you share any folder and add the guest account to the list of users who can accesss that specific folder, this also includes to Turn off password Protected Sharing in 'Advanced Sharing Settings'

The other way to do this where you only enter a password once is to join a Homegroup. if you have a network of 2 or more computers, they can all connect to a homegroup and access all the files they need from each other, and anyone outside the group needs a 1 time password to be able to access your network, this was introduced in windows 7.

Task vs Thread differences

The Thread class is used for creating and manipulating a thread in Windows.

A Task represents some asynchronous operation and is part of the Task Parallel Library, a set of APIs for running tasks asynchronously and in parallel.

In the days of old (i.e. before TPL) it used to be that using the Thread class was one of the standard ways to run code in the background or in parallel (a better alternative was often to use a ThreadPool), however this was cumbersome and had several disadvantages, not least of which was the performance overhead of creating a whole new thread to perform a task in the background.

Nowadays using tasks and the TPL is a far better solution 90% of the time as it provides abstractions which allows far more efficient use of system resources. I imagine there are a few scenarios where you want explicit control over the thread on which you are running your code, however generally speaking if you want to run something asynchronously your first port of call should be the TPL.

When should I use a table variable vs temporary table in sql server?

Use a table variable if for a very small quantity of data (thousands of bytes)

Use a temporary table for a lot of data

Another way to think about it: if you think you might benefit from an index, automated statistics, or any SQL optimizer goodness, then your data set is probably too large for a table variable.

In my example, I just wanted to put about 20 rows into a format and modify them as a group, before using them to UPDATE / INSERT a permanent table. So a table variable is perfect.

But I am also running SQL to back-fill thousands of rows at a time, and I can definitely say that the temporary tables perform much better than table variables.

This is not unlike how CTE's are a concern for a similar size reason - if the data in the CTE is very small, I find a CTE performs as good as or better than what the optimizer comes up with, but if it is quite large then it hurts you bad.

My understanding is mostly based on, which has a lot more detail.

Copy table to a different database on a different SQL Server

If it’s only copying tables then linked servers will work fine or creating scripts but if secondary table already contains some data then I’d suggest using some third party comparison tool.

I’m using Apex Diff but there are also a lot of other tools out there such as those from Red Gate or Dev Art...

Third party tools are not necessary of course and you can do everything natively it’s just more convenient. Even if you’re on a tight budget you can use these in trial mode to get things done….

Here is a good thread on similar topic with a lot more examples on how to do this in pure sql.

PHP shorthand for isset()?

Update for PHP 7 (thanks shock_gone_wild)

PHP 7 introduces the so called null coalescing operator which simplifies the below statements to:

$var = $var ?? "default";

Before PHP 7

No, there is no special operator or special syntax for this. However, you could use the ternary operator:

$var = isset($var) ? $var : "default";

Or like this:

isset($var) ?: $var = 'default';

git pull remote branch cannot find remote ref

check your branch on your repo. maybe someone delete it.

Converting JSON to XML in Java

Underscore-java library has static method U.jsonToXml(jsonstring). I am the maintainer of the project. Live example

import com.github.underscore.lodash.U;

public class MyClass {
    public static void main(String args[]) {
        String json = "{\"name\":\"JSON\",\"integer\":1,\"double\":2.0,\"boolean\":true,\"nested\":{\"id\":42},\"array\":[1,2,3]}";  
        String xml = U.jsonToXml(json);  


<?xml version="1.0" encoding="UTF-8"?>
  <integer number="true">1</integer>
  <double number="true">2.0</double>
  <boolean boolean="true">true</boolean>
    <id number="true">42</id>
  <array number="true">1</array>
  <array number="true">2</array>
  <array number="true">3</array>

How to get numeric value from a prompt box?

You have to use parseInt() to convert

For eg.

  var z = parseInt(x) + parseInt(y);

use parseFloat() if you want to handle float value.

How to use the new Material Design Icon themes: Outlined, Rounded, Two-Tone and Sharp?

As of 12/05/2020, You need to

1. include CSS:

<link href="|Material+Icons+Outlined|Material+Icons+Two+Tone|Material+Icons+Round|Material+Icons+Sharp" rel="stylesheet">

2. Use it like this:

<i class="material-icons">account_balance</i>
<i class="material-icons material-icons-outlined">account_balance</i>
<i class="material-icons material-icons-two-tone">account_balance</i>
<i class="material-icons material-icons-sharp">account_balance</i>
<i class="material-icons material-icons-round">account_balance</i>

Note: For example, to use outlined style, You need to specify material-icons AND material-icons-outlined classes.

Spring Data JPA and Exists query

You can use .exists (return boolean) in jpaRepository.


        jsRespon.setStatusDescription("SUCCESS ADD TO DB");
        jsRespon.setStatusCode("ID already exists is database");

Prevent overwriting a file using cmd if exist

As in the answer of Escobar Ceaser, I suggest to use quotes arround the whole path. It's the common way to wrap the whole path in "", not only separate directory names within the path.

I had a similar issue that it didn't work for me. But it was no option to use "" within the path for separate directory names because the path contained environment variables, which theirself cover more than one directory hierarchies. The conclusion was that I missed the space between the closing " and the (

The correct version, with the space before the bracket, would be

If NOT exist "C:\Documents and Settings\John\Start Menu\Programs\Software Folder" (
 start "\\filer\repo\lab\software\myapp\setup.exe"

How to parse XML using shellscript?

Try using xpath. You can use it to parse elements out of an xml tree.

Directory-tree listing in Python

I wrote a long version, with all the options I might need:

I guess it will fit here too:

#!/usr/bin/env python

import os
import sys

def ls(dir, hidden=False, relative=True):
    nodes = []
    for nm in os.listdir(dir):
        if not hidden and nm.startswith('.'):
        if not relative:
            nm = os.path.join(dir, nm)
    return nodes

def find(root, files=True, dirs=False, hidden=False, relative=True, topdown=True):
    root = os.path.join(root, '')  # add slash if not there
    for parent, ldirs, lfiles in os.walk(root, topdown=topdown):
        if relative:
            parent = parent[len(root):]
        if dirs and parent:
            yield os.path.join(parent, '')
        if not hidden:
            lfiles   = [nm for nm in lfiles if not nm.startswith('.')]
            ldirs[:] = [nm for nm in ldirs  if not nm.startswith('.')]  # in place
        if files:
            for nm in lfiles:
                nm = os.path.join(parent, nm)
                yield nm

def test(root):
    print "* directory listing, with hidden files:"
    print ls(root, hidden=True)
    print "* recursive listing, with dirs, but no hidden files:"
    for f in find(root, dirs=True):
        print f

if __name__ == "__main__":

find filenames NOT ending in specific extensions on Unix?

$ find . -name \*.exe -o -name \*.dll -o -print

The first two -name options have no -print option, so they skipped. Everything else is printed.

How can you profile a Python script?

With a statistical profiler like austin, no instrumentation is required, meaning that you can get profiling data out of a Python application simply with

austin python3

The raw output isn't very useful, but you can pipe that to to get a flame graph representation of that data that gives you a breakdown of where the time (measured in microseconds of real time) is being spent.

austin python3 | > my_script_profile.svg

Updating Python on Mac

I wanted to achieve the same today. The Mac with Snow Leopard comes with Python 2.6.1 version.

Since multiple Python versions can coexist, I downloaded Python 3.2.3 from:

After installation the newer Python will be available under the Application folder and the IDE there uses 3.2.3 version of Python.

From the shell, python3 works with the newer version. That serves the purpose :)

Pandas: Setting no. of max rows

Personally, I like setting the options directly with an assignment statement as it is easy to find via tab completion thanks to iPython. I find it hard to remember what the exact option names are, so this method works for me.

For instance, all I have to remember is that it begins with pd.options


enter image description here

Most of the options are available under display


enter image description here

From here, I usually output what the current value is like this:


I then set it to what I want it to be:

pd.options.display.max_rows = 100

Also, you should be aware of the context manager for options, which temporarily sets the options inside of a block of code. Pass in the option name as a string followed by the value you want it to be. You may pass in any number of options in the same line:

with pd.option_context('display.max_rows', 100, 'display.max_columns', 10):
    some pandas stuff

You can also reset an option back to its default value like this:


And reset all of them back:


It is still perfectly good to set options via pd.set_option. I just find using the attributes directly is easier and there is less need for get_option and set_option.

Should I check in folder "node_modules" to Git when creating a Node.js app on Heroku?

You should not include folder node_modules in your .gitignore file (or rather you should include folder node_modules in your source deployed to Heroku).

If folder node_modules:

  • exists then npm install will use those vendored libraries and will rebuild any binary dependencies with npm rebuild.
  • doesn't exist then npm install will have to fetch all dependencies itself which adds time to the slug compile step.

See the Node.js buildpack source for these exact steps.

However, the original error looks to be an incompatibility between the versions of npm and Node.js. It is a good idea to always explicitly set the engines section of your packages.json file according to this guide to avoid these types of situations:

  "name": "myapp",
  "version": "0.0.1",
  "engines": {
    "node": "0.8.x",
    "npm":  "1.1.x"

This will ensure development/production parity and reduce the likelihood of such situations in the future.

get all the images from a folder in php

You can simply show your actual image directory(less secure). By just 2 line of code.

 $dir = base_url()."photos/";

echo"<a href=".$dir.">Photo Directory</a>";

Spring Rest POST Json RequestBody Content type not supported

If you use lombok, you can get that error if you screw up naming of @JsonDeserialize, for example:

@Builder(toBuilder = true)
@JsonDeserialize(builder = SomeClass.SomeOtherClassBuilder.class)
public class SomeClass {
    public static class SomeOtherClassBuilder {

It should be:

@Builder(toBuilder = true)
@JsonDeserialize(builder = SomeClass.SomeClassBuilder.class)
public class SomeClass {
    public static class SomeClassBuilder {

It is very easy to do that when you do refactoring of class name and forget about Builder... and then you have many hours of joy while you search for reason of error, while having as help only extremely unhelpful exception message.

Large Numbers in Java

Depending on what you're doing you might like to take a look at GMP ( which is a high-performance multi-precision library. To use it in Java you need JNI wrappers around the binary library.

See some of the Alioth Shootout code for an example of using it instead of BigInteger to calculate Pi to an arbitrary number of digits.

Append an object to a list in R in amortized constant time, O(1)?

This is a straightforward way to add items to an R List:

# create an empty list:
small_list = list()

# now put some objects in it:
small_list$k1 = "v1"
small_list$k2 = "v2"
small_list$k3 = 1:10

# retrieve them the same way:
# returns "v1"

# "index" notation works as well:

Or programmatically:

kx = paste(LETTERS[1:5], 1:5, sep="")
vx = runif(5)
lx = list()
cn = 1

for (itm in kx) { lx[itm] = vx[cn]; cn = cn + 1 }

# returns 5

Difference between OData and REST web services

REST stands for REpresentational State Transfer which is a resource based architectural style. Resource based means that data and functionalities are considered as resources.

OData is a web based protocol that defines a set of best practices for building and consuming RESTful web services. OData is a way to create RESTful web services thus an implementation of REST.

System.Net.Http: missing from namespace? (using .net 4.5)

With the Nuget Package Manager install Microsoft.AspNet.WebApi.Core.

After this:

using System.Web.Http;

or if you use VB

imports System.Web.Http

Core dump file is not generated

The answers given here cover pretty well most scenarios for which core dump is not created. However, in my instance, none of these applied. I'm posting this answer as an addition to the other answers.

If your core file is not being created for whatever reason, I recommend looking at the /var/log/messages. There might be a hint in there to why the core file is not created. In my case there was a line stating the root cause:

Executable '/path/to/executable' doesn't belong to any package

To work around this issue edit /etc/abrt/abrt-action-save-package-data.conf and change ProcessUnpackaged from 'no' to 'yes'.

ProcessUnpackaged = yes

This setting specifies whether to create core for binaries not installed with package manager.

Change Orientation of Bluestack : portrait/landscape mode

New version 4.100.x.xxxx

Try this:

More Apps > Android Settings > Accessibility > Auto-rotate screen = Enabled

enter image description here

c# write text on bitmap

Bitmap bmp = new Bitmap("filename.bmp");

RectangleF rectf = new RectangleF(70, 90, 90, 50);

Graphics g = Graphics.FromImage(bmp);

g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.DrawString("yourText", new Font("Tahoma",8), Brushes.Black, rectf);



Passing variables, creating instances, self, The mechanics and usage of classes: need explanation

The whole point of a class is that you create an instance, and that instance encapsulates a set of data. So it's wrong to say that your variables are global within the scope of the class: say rather that an instance holds attributes, and that instance can refer to its own attributes in any of its code (via self.whatever). Similarly, any other code given an instance can use that instance to access the instance's attributes - ie instance.whatever.

Getting full-size profile picture

For Angular:

getUserPicture(userId) {   
FB.api('/' + userId, {fields: 'picture.width(800).height(800)'}, function(response) {

How to cast DATETIME as a DATE in mysql?

Use DATE() function:

select * from follow_queue group by DATE(follow_date)

Return multiple values in JavaScript?

I know of two ways to do this: 1. Return as Array 2. Return as Object

Here's an example I found:

// Defining function
function divideNumbers(dividend, divisor){
    var quotient = dividend / divisor;
    var arr = [dividend, divisor, quotient];
    return arr;

// Store returned value in a variable
var all = divideNumbers(10, 2);

// Displaying individual values
alert(all[0]); // 0utputs: 10
alert(all[1]); // 0utputs: 2
alert(all[2]); // 0utputs: 5

// Defining function
function divideNumbers(dividend, divisor){
    var quotient = dividend / divisor;
    var obj = {
        dividend: dividend,
        divisor: divisor,
        quotient: quotient
    return obj;

// Store returned value in a variable
var all = divideNumbers(10, 2);

// Displaying individual values
alert(all.dividend); // 0utputs: 10
alert(all.divisor); // 0utputs: 2
alert(all.quotient); // 0utputs: 5

SonarQube Exclude a directory

This worked for me:


It excludes any .js and .css files under any of the sub directories of a folder "wwwroot" appearing as one of the sub directories of the "src" folder (project root).

Why don’t my SVG images scale using the CSS "width" property?

The transform CSS property lets you rotate, scale, skew, or translate an element.

So you can easily use the transform: scale(2.5); option to scale 2.5 times for example.

How to catch a specific SqlException error?

Sort of, kind of. See Cause and Resolution of Database Engine Errors

class SqllErrorNumbers
   public const int BadObject = 208;
   public const int DupKey = 2627;

catch(SqlException sex)
   foreach(SqlErrorCode err in sex.Errors)
      switch (err.Number)
      case SqlErrorNumber.BadObject:...
      case SqllErrorNumbers.DupKey: ...

The problem though is that a good DAL layer would us TRY/CATCH inside the T-SQL (stored procedures), with a pattern like Exception handling and nested transactions. Alas a T-SQL TRY/CATCH block cannot raise the original error code, will have to raise a new error, with code above 50000. This makes client side handling a problem. In the next version of SQL Server there is a new THROW construct that allow to re-raise the original exception from T-SQL catch blocks.

LOAD DATA INFILE Error Code : 13

If you are using Fedora/RHEL/CentOO you can disable temporarily SELinux:

setenforce 0

Load your data and then enable it back:

setenforce 1

DISABLE the Horizontal Scroll

koala_dev answered that this will work:

html, body {
   max-width: 100%;
   overflow-x: hidden;

And MarkWPiper comments that ":-/ Caused touch / momentum scrolling to stop working on iPhone"

The solution to keep touch / momentum on iPhone is to add this line inside the css block for html,body:


Recommended way to insert elements into map

  1. insert is not a recommended way - it is one of the ways to insert into map. The difference with operator[] is that the insert can tell whether the element is inserted into the map. Also, if your class has no default constructor, you are forced to use insert.
  2. operator[] needs the default constructor because the map checks if the element exists. If it doesn't then it creates one using default constructor and returns a reference (or const reference to it).

Because map containers do not allow for duplicate key values, the insertion operation checks for each element inserted whether another element exists already in the container with the same key value, if so, the element is not inserted and its mapped value is not changed in any way.

changing default x range in histogram matplotlib

plt.hist(hmag, 30, range=[6.5, 12.5], facecolor='gray', align='mid')

CSS3 transform not working

-webkit-transform is no more needed

ms already support rotation ( -ms-transform: rotate(-10deg); )

try this:

li a {

    -webkit-transform: rotate(-10deg);
    -moz-transform: rotate(-10deg);
    -o-transform: rotate(-10deg);
    -ms-transform: rotate(-10deg);
    -sand-transform: rotate(10deg);
    display: block;
    position: fixed;

The most efficient way to implement an integer based power function pow(int, int)

I use recursive, if the exp is even,5^10 =25^5.

int pow(float base,float exp){
   if (exp==0)return 1;
   else if(exp>0&&exp%2==0){
      return pow(base*base,exp/2);
   }else if (exp>0&&exp%2!=0){
      return base*pow(base,exp-1);

Create a directory if it does not exist and then create the files in that directory as well

If you create a web based application, the better solution is to check the directory exists or not then create the file if not exist. If exists, recreate again.

    private File createFile(String path, String fileName) throws IOException {
       ClassLoader classLoader = getClass().getClassLoader();
       File file = new File(classLoader.getResource(".").getFile() + path + fileName);

       // Lets create the directory
       try {
       } catch (Exception err){
           System.out.println("ERROR (Directory Create)" + err.getMessage());

       // Lets create the file if we have credential
       try {
       } catch (Exception err){
           System.out.println("ERROR (File Create)" + err.getMessage());
       return  file;

Java Does Not Equal (!=) Not Working?

You need to use the method equals() when comparing a string, otherwise you're just comparing the object references to each other, so in your case you want:

if (!statusCheck.equals("success")) {

How to remove non UTF-8 characters from text file

cat foo.txt | strings -n 8 > bar.txt

will do the job.

What does this mean? "Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM"

if you still need to use the double-colon then make sure your on PHP 5.3+

Table fixed header and scrollable body

Used this link,, by Hashem Qolami at the original posts' comments and used display:inline-blocks instead of floats. Fixes borders if the table has the class 'table-bordered' also.

table.scroll {
  width: 100%;  
  &.table-bordered {
    td, th {
      border-top: 0;
      border-right: 0;
    th {
      border-bottom-width: 1px;
    th:first-child {
      border-right: 0;
      border-left: 0;
  tbody {
    height: 200px;
    overflow-y: auto;
    overflow-x: hidden;  
  tbody, thead {
    display: block;
  tr {
    width: 100%;
    display: block;
  th, td {
    display: inline-block;

  td {
    height: 46px; //depends on your site

Then just add the widths of the td and th

table.table-prep {
  tr > td.type,
  tr > th.type{
    width: 10%;
  tr >,
  tr >,
  tr > td.notes,
  tr > th.notes,
  tr > td.quantity,
  tr > th.quantity{
    width: 30%;

Dump a list in a pickle file and retrieve it back later

Pickling will serialize your list (convert it, and it's entries to a unique byte string), so you can save it to disk. You can also use pickle to retrieve your original list, loading from the saved file.

So, first build a list, then use pickle.dump to send it to a file...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> mylist = ['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]
>>> import pickle
>>> with open('parrot.pkl', 'wb') as f:
...   pickle.dump(mylist, f)

Then quit and come back later… and open with pickle.load...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> with open('parrot.pkl', 'rb') as f:
...   mynewlist = pickle.load(f)
>>> mynewlist
['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]

How to append output to the end of a text file

Use the >> operator to append text to a file.

Best way to stress test a website

The ab (apache bench) tool allows you to send many requests to a single page and you specify how many clients you want to be used and how many concurrent connection you want.

This may be the first step when developing a site. Just test some pages with a specific load. This way of benchmarking may have some problem, like caching being over used.

Later you may want a tool that simulate some concrete traffic and not for a single page. I don't have a refence handy on such tool yet.

Get index of selected option with jQuery

selectedIndex is a JavaScript Select Property. For jQuery you can use this code:

jQuery(document).ready(function($) {
  $("#dropDownMenuKategorie").change(function() {
    // I personally prefer using console.log(), but if you want you can still go with the alert().

How to terminate a thread when main program ends?

Use the atexit module of Python's standard library to register "termination" functions that get called (on the main thread) on any reasonably "clean" termination of the main thread, including an uncaught exception such as KeyboardInterrupt. Such termination functions may (though inevitably in the main thread!) call any stop function you require; together with the possibility of setting a thread as daemon, that gives you the tools to properly design the system functionality you need.

When to choose mouseover() and hover() function?

From the official jQuery documentation

  • .mouseover()
    Bind an event handler to the "mouseover" JavaScript event, or trigger that event on an element.

  • .hover() Bind one or two handlers to the matched elements, to be executed when the mouse pointer enters and leaves the elements.

    Calling $(selector).hover(handlerIn, handlerOut) is shorthand for: $(selector).mouseenter(handlerIn).mouseleave(handlerOut);

  • .mouseenter()

    Bind an event handler to be fired when the mouse enters an element, or trigger that handler on an element.

    mouseover fires when the pointer moves into the child element as well, while mouseenter fires only when the pointer moves into the bound element.

What this means

Because of this, .mouseover() is not the same as .hover(), for the same reason .mouseover() is not the same as .mouseenter().

$('selector').mouseover(over_function) // may fire multiple times

// enter and exit functions only called once per element per entry and exit
$('selector').hover(enter_function, exit_function) 

ASP.NET Forms Authentication failed for the request. Reason: The ticket supplied has expired

AS Scott mentioned here After windows installed security update for .net framework, you will meet this problem. just modify the configuration section in your web.config file and switch to a different cookie name.

How to overload __init__ method based on argument type?

Excellent question. I've tackled this problem as well, and while I agree that "factories" (class-method constructors) are a good method, I would like to suggest another, which I've also found very useful:

Here's a sample (this is a read method and not a constructor, but the idea is the same):

def read(self, str=None, filename=None, addr=0):
    """ Read binary data and return a store object. The data
        store is also saved in the interal 'data' attribute.

        The data can either be taken from a string (str 
        argument) or a file (provide a filename, which will 
        be read in binary mode). If both are provided, the str 
        will be used. If neither is provided, an ArgumentError 
        is raised.
    if str is None:
        if filename is None:
            raise ArgumentError('Please supply a string or a filename')

        file = open(filename, 'rb')
        str =
    ... # rest of code

The key idea is here is using Python's excellent support for named arguments to implement this. Now, if I want to read the data from a file, I say:"blob.txt")

And to read it from a string, I say:"\x34\x55")

This way the user has just a single method to call. Handling it inside, as you saw, is not overly complex

background:none vs background:transparent what is the difference?

To complement the other answers: if you want to reset all background properties to their initial value (which includes background-color: transparent and background-image: none) without explicitly specifying any value such as transparent or none, you can do so by writing:

background: initial;

Jenkins restrict view of jobs per user

Think this is, what you are searching for: Allow access to specific projects for Users

Short description without screenshots:
Use Jenkins "Project-based Matrix Authorization Strategy" under "Manage Jenkins" => "Configure System". On the configuration page of each project, you now have "Enable project-based security". Now add each user you want to authorize.

Simple parse JSON from URL on Android and display in listview

try as:

 // your get json request to server.. 
 HttpResponse response = httpClient.execute(httpPost);
 HttpEntity entity = response.getEntity();

 if(entity != null){
    JSONObject respObject = new JSONObject(EntityUtils.toString(entity));
    String active = respObject.getString("active");   
    String name = respObject.getString("name");  
    String tab1_text = respObject.getString("tab1_text");  
       //Do something here...

see this example for Getting and parsing json response from server :

Is using 'var' to declare variables optional?

Check out this Fiddle:

function doMe(){

a = "123"; // will be global
var b = "321"; // local to doMe
alert("a:"+a+"  --  b:"+b);

b = "something else"; // still local (not global)
alert("a:"+a+"  --  b:"+b);


alert("a:"+a+"  --  b:"+b); // `b` will not be defined, check console.log

Insert a string at a specific index

I know this is an old thread, however, here is a really effective approach.

var tn = document.createTextNode("I am just  to help")
t.insertData(10, "trying");

What's great about this is that it coerces the node content. So if this node were already on the DOM, you wouldn't need to use any query selectors or update the innerText. The changes would reflect due to its binding.

Were you to need a string, simply access the node's text content property.

#=> "I am just trying to help"

How do I make a list of data frames?

You can also access specific columns and values in each list element with [ and [[. Here are a couple of examples. First, we can access only the first column of each data frame in the list with lapply(ldf, "[", 1), where 1 signifies the column number.

ldf <- list(d1 = d1, d2 = d2)  ## create a named list of your data frames
lapply(ldf, "[", 1)
# $d1
#   y1
# 1  1
# 2  2
# 3  3
# $d2
#   y1
# 1  3
# 2  2
# 3  1

Similarly, we can access the first value in the second column with

lapply(ldf, "[", 1, 2)
# $d1
# [1] 4
# $d2
# [1] 6

Then we can also access the column values directly, as a vector, with [[

lapply(ldf, "[[", 1)
# $d1
# [1] 1 2 3
# $d2
# [1] 3 2 1

Erase the current printed console line

You could delete the line using \b

int i;
for (i=0; i<80; i++)

Using IQueryable with Linq

It allows for further querying further down the line. If this was beyond a service boundary say, then the user of this IQueryable object would be allowed to do more with it.

For instance if you were using lazy loading with nhibernate this might result in graph being loaded when/if needed.

CSS rule to apply only if element has BOTH classes

If you need a progmatic solution this should work in jQuery:

$("").css("width", 200);

Rails DB Migration - How To Drop a Table?

Open you rails console

ActiveRecord::Base.connection.execute("drop table table_name")

Finding which process was killed by Linux OOM killer

Try this out:

grep -i 'killed process' /var/log/messages

How do I measure the execution time of JavaScript code with callbacks?

You could also try exectimer. It gives you feedback like:

var t = require("exectimer");

var myFunction() {
   var tick = new t.tick("myFunction");
   // do some processing and end this tick

// Display the results
console.log(t.timers.myFunction.duration()); // total duration of all ticks
console.log(t.timers.myFunction.min()); // minimal tick duration
console.log(t.timers.myFunction.max()); // maximal tick duration
console.log(t.timers.myFunction.mean()); // mean tick duration
console.log(t.timers.myFunction.median()); // median tick duration

[edit] There is an even simpler way now to use exectime. Your code could be wrapped like this:

var t = require('exectimer'),
Tick = t.Tick;

for(var i = 1; i < LIMIT; i++){
    Tick.wrap(function saveUsers(done) {{id : i, name : "MongoUser [" + i + "]"}, function(err, saved) {
            if( err || !saved ) console.log("Error");
            else console.log("Saved");

// Display the results
console.log(t.timers.myFunction.duration()); // total duration of all ticks
console.log(t.timers.saveUsers.min()); // minimal tick duration
console.log(t.timers.saveUsers.max()); // maximal tick duration
console.log(t.timers.saveUsers.mean()); // mean tick duration
console.log(t.timers.saveUsers.median()); // median tick duration

Cleanest way to write retry logic?

I know this answer is very old but I just wanted to comment on this because I have run into issues using these while, do, whatever statement with counters.

Over the years I have settled on a better approach I think. That is to use some sort of event aggregation like a reactive extensions "Subject" or the like. When a try fails, you simply publish an event saying the try failed, and have the aggregator function re-schedule the event. This allows you much more control over the retry without polluting the call itself with a bunch of retry loops and what not. Nor are you tying up a single thread with a bunch of thread sleeps.

How can I return the sum and average of an int array?

If you are using visual studio 2005 then

public void sumAverageElements(int[] arr)
     int size =arr.Length;
     int sum = 0;
     int average = 0;

     for (int i = 0; i < size; i++)
          sum += arr[i];

     average = sum / size; // sum divided by total elements in array

     Console.WriteLine("The Sum Of Array Elements Is : " + sum);
     Console.WriteLine("The Average Of Array Elements Is : " + average);

Eclipse: All my projects disappeared from Project Explorer

It seems it happens to us all. I was happily hacking away at javascript, nowhere near all the nasty hibernate java stuff, and boom, "cant find org.jboss.logging.BasicLoging". I havent touched anything!. After an hour or so of trying to make that appear, restarting servers, mysql, eclipse, adding jars that weren't needed before,I deployed the fix all solution, the off button. Then zap, no project. (I am still none the wiser as to why calling Configuration() should now require jboss-logging...jar, maybe I needed it all along for when bad things happen)

My input is

  1. use git, keep as little of your stuff in the eclipse workspace area as possible. Then just import project from existing git repo when eclipse loses it's marbles.

  2. I also lost my server config. it's there but eclipse insists there no server config stuff and bombs. So make another one, I've expressed my feelings about eclipse in my new server name, and copy your apache xml configs (workspace/Servers/I_Love_Eclipse) over from the original perfectly good directory.

R: invalid multibyte string

This happened to me because I had the 'copyright' symbol in one of my strings! Once it was removed, problem solved.

A good rule of thumb, make sure that characters not appearing on your keyboard are removed if you are seeing this error.

How do I open a new fragment from another fragment?

This is more described code of @Narendra's code,

First you need an instance of the 2nd fragment. Then you should have objects of FragmentManager and FragmentTransaction. The complete code is as below,

Fragment2 fragment2=new Fragment2();
FragmentManager fragmentManager=getActivity().getFragmentManager();
FragmentTransaction fragmentTransaction=fragmentManager.beginTransaction();

Hope this will work. In case you use androidx, you need getSupportFragmentManager() instead of getFragmentManager().

Java String split removed empty values

String[] split = data.split("\\|",-1);

This is not the actual requirement in all the time. The Drawback of above is show below:

Scenerio 1:
When all data are present:
    String data = "5|6|7||8|9|10|";
    String[] split = data.split("\\|");
    String[] splt = data.split("\\|",-1);
    System.out.println(split.length); //output: 7
    System.out.println(splt.length); //output: 8

When data is missing:

Scenerio 2: Data Missing
    String data = "5|6|7||8|||";
    String[] split = data.split("\\|");
    String[] splt = data.split("\\|",-1);
    System.out.println(split.length); //output: 5
    System.out.println(splt.length); //output: 8

Real requirement is length should be 7 although there is data missing. Because there are cases such as when I need to insert in database or something else. We can achieve this by using below approach.

    String data = "5|6|7||8|||";
    String[] split = data.split("\\|");
    String[] splt = data.replaceAll("\\|$","").split("\\|",-1);
    System.out.println(split.length); //output: 5
    System.out.println(splt.length); //output:7

What I've done here is, I'm removing "|" pipe at the end and then splitting the String. If you have "," as a seperator then you need to add ",$" inside replaceAll.

Illegal mix of collations MySQL Error

CONVERT(column1 USING utf8)

Solves my problem. Where column1 is the column which gives me this error.

Get the number of rows in a HTML table

The following code assumes that your table has the ID 'MyTable'

<script language="JavaScript">
var oRows = document.getElementById('MyTable').getElementsByTagName('tr');
var iRowCount = oRows.length;

alert('Your table has ' + iRowCount + ' rows.');

Answer taken from :, which is the first result on google for the query : "Get the number of rows in a HTML table" ;)

how to parse json using groovy

        def jsonFile = new File('File Path');
        JsonSlurper jsonSlurper = new JsonSlurper();
        def parseJson = jsonSlurper.parse(jsonFile)
        String json = JsonOutput.toJson(parseJson)
        def prettyJson = JsonOutput.prettyPrint(json)

What does ||= (or-equals) mean in Ruby?

a ||= b

is equivalent to

a || a = b

and not

a = a || b

because of the situation where you define a hash with a default (the hash will return the default for any undefined keys)

a = #Which is: {}

if you use:

a[10] ||= 10 #same as a[10] || a[10] = 10

a is still:


but when you write it like so:

a[10] = a[10] || 10

a becomes:

{10 => true}

because you've assigned the value of itself at key 10, which defaults to true, so now the hash is defined for the key 10, rather than never performing the assignment in the first place.

Check if a process is running or not on Windows with Python

Would you be happy with your Python command running another program to get the info?

If so, I'd suggest you have a look at PsList and all its options. For example, The following would tell you about any running iTunes process

PsList itunes

If you can work out how to interpret the results, this should hopefully get you going.


When I'm not running iTunes, I get the following:

pslist v1.29 - Sysinternals PsList
Copyright (C) 2000-2009 Mark Russinovich

Process information for CLARESPC:

Name                Pid Pri Thd  Hnd   Priv        CPU Time    Elapsed Time
iTunesHelper       3784   8  10  229   3164     0:00:00.046     3:41:05.053

With itunes running, I get this one extra line:

iTunes              928   8  24  813 106168     0:00:08.734     0:02:08.672

However, the following command prints out info only about the iTunes program itself, i.e. with the -e argument:

pslist -e itunes

Find and replace string values in list

You can use, for example:

words = [word.replace('[br]','<br />') for word in words]