Programs & Examples On #Mde

Error : Program type already present:$Behavior

This can happens when one library is loaded into gradle several times. Most often through other connected libraries.

Remove a implementation this library in build.gradle

Then Build -> Clear project

and you can run the assembly)

java.lang.RuntimeException: Unable to merge dex in Android Studio 3.0

Enable Multidex through build.gradle of your app module

multiDexEnabled true

Same as below -

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId ""
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        multiDexEnabled true //Add this
        testInstrumentationRunner ""
    buildTypes {
        release {
            shrinkResources true
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), ''

Then follow below steps -

  1. From the Build menu -> press the Clean Project button.
  2. When task completed, press the Rebuild Project button from the Build menu.
  3. From menu File -> Invalidate cashes / Restart

compile is now deprecated so it's better to use implementation or api

Android Studio 3.0 Execution failed for task: unable to merge dex

In my case changing firebase library version from 2.6.0 to 2.4.2 fixed the issue

Unable to merge dex

In case the top answers haven't worked for you, your issue may be that you have multiple dependencies that depend on the same library.

Here are some debugging tips. In this sample code, is the offending library.

Always clean and rebuild every time you modify to check your solution!

  1. Build with the --stacktrace flag on for more detail. It will complain about a class, Google that class to find the library. Here's how you can set up Android studio to always run gradle with the --stacktrace flag.

  2. Take a glance at the Gradle Console in Android Studio View > Tool Windows > Gradle Console after a build

  3. Check for repeated dependences by running ./gradlew -q app:dependencies. You can re-run this each time you modify the your build.gradle.

  4. In build.gradle,

    android {
            configurations.all {
                resolutionStrategy {
                    // Force a particular version of the library 
                    // across all dependencies that have that dependency
                    force ''
  5. In build.gradle,

    dependencies {
        implementation('') {
            // Exclude the library for this particular import
            exclude group: ''
  6. In build.gradle,

    android {
        configurations.all {
            resolutionStrategy {
                // Completely exclude the library. Works for transitive
                // dependencies.
                exclude group: ''
  7. If some of your dependencies are in jar files, open up the jar files and see if there are any conflicting class names. If they are, you will probably have to re-build the jars with new class names or look into shading.

Some more background reading:

How to change the integrated terminal in visual studio code or VSCode

I know is late but you can quickly accomplish that by just typing Ctrl + Shift + p and then type default, it will show an option that says

Terminal: Select Default Shell

, it will then display all the terminals available to you.

How do I select which GPU to run a job on?

You can also set the GPU in the command line so that you don't need to hard-code the device into your script (which may fail on systems without multiple GPUs). Say you want to run your script on GPU number 5, you can type the following on the command line and it will run your script just this once on GPU#5:


ImportError: No module named google.protobuf

The reason for this would be mostly due to the evil command pip install google. I was facing a similar issue for google-cloud, but the same steps are true for protobuf as well. Both of our issues deal with a namespace conflict over the 'google' namespace.

If you executed the pip install google command like I did then you are in the correct place. The google package is actually not owned by Google which can be confirmed by the command pip show google which outputs:

 Name: google
 Version: 1.9.3
 Summary: Python bindings to the Google search engine.
 Author: Mario Vilas
 Author-email: [email protected]
 License: UNKNOWN
 Location: <Path where this package is installed>
 Requires: beautifulsoup4

Because of this package, the google namespace is reserved and coincidentally google-cloud also expects namespace google > cloud and it results in a namespace collision for these two packages.

See in below screenshot namespace of google-protobuf as google > protobuf

google-cloud namespace screenshot google > cloud > datastore

Solution :- Unofficial google package need to be uninstalled which can be done by using pip uninstall google after this you can reinstall google-cloud using pip install google-cloud or protobuf using pip install protobuf

FootNotes :- Assuming you have installed the unofficial google package by mistake and you don't actually need it along with google-cloud package. If you need both unofficial google and google-cloud above solution won't work.

Furthermore, the unofficial 'google' package installs with it 'soupsieve' and 'beautifulsoup4'. You may want to also uninstall those packages.

Let me know if this solves your particular issue.

IE and Edge fix for object-fit: cover;

Here is the only CSS solution to fix this. Use the below css.

.row-fluid {
  display: table;

.row-fluid .span6 {
  display: table-cell;
  vertical-align: top;

.vc_single_image-wrapper {
  position: relative;

.vc_single_image-wrapper .image-wrapper {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  background-size: cover;
  background-repeat: no-repeat;
  background-position: 50% 50%;

HTML from the OP:

<div class="vc_single_image-wrapper   vc_box_border_grey">
  <div class="image-wrapper" style="background-image: url(;"></div>

try this, it should work. also remove float from .row-fluid .span6

android : Error converting byte to dex

Try installing via :app:installDebug. If it works then it is related to Android Studio's caches. I removed .gradle/ folder inside my project and it works.

npm install -g less does not work: EACCES: permission denied

enter image description hereUse sudo -i to switch to $root, then execute npm install -g xxxx

Recyclerview inside ScrollView not scrolling smoothly

<?xml version="1.0" encoding="utf-8"?>
< xmlns:android=""




                    app:layout_constraintRight_toRightOf="parent" />



                    app:layout_constraintRight_toRightOf="parent" />





This code is working for in ConstraintLayout android

LocalDate to java.util.Date and vice versa simplest conversion?

You can convert the java.util.Date object into a String object, which will format the date as yyyy-mm-dd.

LocalDate has a parse method that will convert it to a LocalDate object. The string must represent a valid date and is parsed using DateTimeFormatter.ISO_LOCAL_DATE.

Date to LocalDate


Can't get private key with openssl (no start line:pem_lib.c:703:Expecting: ANY PRIVATE KEY)

It looks like you have a certificate in DER format instead of PEM. This is why it works correctly when you provide the -inform PEM command line argument (which tells openssl what input format to expect).

It's likely that your private key is using the same encoding. It looks as if the openssl rsa command also accepts a -inform argument, so try:

openssl rsa -text -in file.key -inform DER

A PEM encoded file is a plain-text encoding that looks something like:


While DER is a binary encoding format.


Sometimes keys are distributed in PKCS#8 format (which can be either PEM or DER encoded). Try this and see what you get:

openssl pkcs8 -in file.key -inform der

Error 405 (Method Not Allowed) Laravel 5

In my case the route in my router was:

Route::post('/new-order', 'Api\OrderController@initiateOrder')->name('newOrder');

and from the client app I was posting the request to:


So, because of the trailing slash I got a 405. Hope it helps someone

How can a divider line be added in an Android RecyclerView?

yqritc's RecyclerView-FlexibleDivider makes this a one liner. First add this to your build.gradle:

compile 'com.yqritc:recyclerview-flexibledivider:1.4.0' // requires jcenter()

Now you can configure and add a divder where you set your recyclerView's adapter:

recyclerView.addItemDecoration(new HorizontalDividerItemDecoration.Builder(this).color(Color.RED).sizeResId(R.dimen.divider).marginResId(R.dimen.leftmargin, R.dimen.rightmargin).build());

Hadoop cluster setup - Connection refused

I was getting the same issue and found that OpenSSH service was not running and it was causing the issue. After starting the SSH service it worked.

To check if SSH service is running or not:

ssh localhost

To start the service, if OpenSSH is already installed:

sudo /etc/init.d/ssh start

Why can I not create a wheel in python?

Update your setuptools, too.

pip install setuptools --upgrade

If that fails too, you could try with additional --force flag.

AttributeError: 'str' object has no attribute

The problem is in your playerMovement method. You are creating the string name of your room variables (ID1, ID2, ID3):

letsago = "ID" + str(self.dirDesc.values())

However, what you create is just a str. It is not the variable. Plus, I do not think it is doing what you think its doing:


If you REALLY needed to find the variable this way, you could use the eval function:

>>>foo = 'Hello World!'
'Hello World!'

or the globals function:

class Foo(object):
    def __init__(self):
        super(Foo, self).__init__()
    def test(self, name):

foo = Foo()
bar = 'Hello World!'

However, instead I would strongly recommend you rethink you class(es). Your userInterface class is essentially a Room. It shouldn't handle player movement. This should be within another class, maybe GameManager or something like that.

Why do multiple-table joins produce duplicate rows?

This might sound like a really basic "DUH" answer, but make sure that the column you're using to Lookup from on the merging file is actually full of unique values!

I noticed earlier today that PowerQuery won't throw you an error (like in PowerPivot) and will happily allow you to run a Many-Many merge. This will result in multiple rows being produced for each record that matches with a non-unique value.

Saving binary data as file using JavaScript from a browser


let bytes = [65,108,105,99,101,39,115,32,65,100,118,101,110,116,117,114,101];_x000D_
let base64data = btoa(String.fromCharCode.apply(null, bytes));_x000D_
let a = document.createElement('a');_x000D_
a.href = 'data:;base64,' + base64data;_x000D_ = 'binFile.txt'; _x000D_;

I convert here binary data to base64 (for bigger data conversion use this) - during downloading browser decode it automatically and save raw data in file. 2020.06.14 I upgrade Chrome to 83.0 and above SO snippet stop working (probably due to sandbox security restrictions) - but JSFiddle version works - here

javax.xml.bind.UnmarshalException: unexpected element. Expected elements are (none)

One of the reasons for this error is the use of the jaxb implementation from the jdk. I am not sure why such a problem can appear in pretty simple xml parsing situations. You may use the latest version of the jaxb library from a public maven repository:


SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I would change the query in the following ways:

  1. Do the aggregation in subqueries. This can take advantage of more information about the table for optimizing the group by.
  2. Combine the second and third subqueries. They are aggregating on the same column. This requires using a left outer join to ensure that all data is available.
  3. By using count(<fieldname>) you can eliminate the comparisons to is null. This is important for the second and third calculated values.
  4. To combine the second and third queries, it needs to count an id from the mde table. These use mde.mdeid.

The following version follows your example by using union all:

SELECT CAST(Detail.ReceiptDate AS DATE) AS "Date",
       SUM(TOTALMAILED) as TotalMailed,
FROM ((select SentDate AS "ReceiptDate", COUNT(*) as TotalMailed,
       from MailDataExtract
       where SentDate is not null
       group by SentDate
      ) union all
      (select MDE.ReturnMailDate AS ReceiptDate, 0,
              COUNT(distinct mde.mdeid) as TOTALUNDELINOTICESRECEIVED,
              SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract MDE left outer join
            DTSharedData.dbo.ScanData SD
            ON SD.ScanDataID = MDE.ReturnScanDataID
       group by MDE.ReturnMailDate;
     ) detail
GROUP BY CAST(Detail.ReceiptDate AS DATE)

The following does something similar using full outer join:

SELECT coalesce(sd.ReceiptDate, mde.ReceiptDate) AS "Date",
FROM (select cast(SentDate as date) AS "ReceiptDate", COUNT(*) as TotalMailed
      from MailDataExtract
      where SentDate is not null
      group by cast(SentDate as date)
     ) sd full outer join
    (select cast(MDE.ReturnMailDate as date) AS ReceiptDate,
            COUNT(distinct mde.mdeID) as TOTALUNDELINOTICESRECEIVED,
            SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
     from MailDataExtract MDE left outer join
          DTSharedData.dbo.ScanData SD
          ON SD.ScanDataID = MDE.ReturnScanDataID
     group by cast(MDE.ReturnMailDate as date)
    ) mde
    on sd.ReceiptDate = mde.ReceiptDate

How to display errors for my MySQLi query?

Just simply add or die(mysqli_error($db)); at the end of your query, this will print the mysqli error.

 mysqli_query($db,"INSERT INTO stockdetails (`itemdescription`,`itemnumber`,`sellerid`,`purchasedate`,`otherinfo`,`numberofitems`,`isitdelivered`,`price`) VALUES ('$itemdescription','$itemnumber','$sellerid','$purchasedate','$otherinfo','$numberofitems','$numberofitemsused','$isitdelivered','$price')") or die(mysqli_error($db));

As a side note I'd say you are at risk of mysql injection, check here How can I prevent SQL injection in PHP?. You should really use prepared statements to avoid any risk.

Using msbuild to execute a File System Publish Profile

Still had trouble after trying all of the answers above (I use Visual Studio 2013). Nothing was copied to the publish folder.

The catch was that if I run MSBuild with an individual project instead of a solution, I have to put an additional parameter that specifies Visual Studio version:


12.0 is for VS2013, replace with the version you use. Once I added this parameter, it just worked.

The complete command line looks like this:

MSBuild C:\PathToMyProject\MyProject.csproj /p:DeployOnBuild=true /p:PublishProfile=MyPublishProfile /p:VisualStudioVersion=12.0

I've found it here:

They state:

If you specify an individual project instead of a solution, you have to add a parameter that specifies the Visual Studio version.

XML Schema Validation : Cannot find the declaration of element

cvc-elt.1: Cannot find the declaration of element 'Root'. [7]

Your schemaLocation attribute on the root element should be xsi:schemaLocation, and you need to fix it to use the right namespace.

You should probably change the targetNamespace of the schema and the xmlns of the document to (since namespaces are supposed to be valid URIs, which Test.Namespace isn't, though urn:Test.Namespace would be ok). Once you do that it should find the schema. The point is that all three of the schema's target namespace, the document's namespace, and the namespace for which you're giving the schema location must be the same.

(though it still won't validate as your <element2> contains an <element3> in the document where the schema expects item)

SQL Server stored procedure creating temp table and inserting value

A SELECT INTO statement creates the table for you. There is no need for the CREATE TABLE statement before hand.

What is happening is that you create #ivmy_cash_temp1 in your CREATE statement, then the DB tries to create it for you when you do a SELECT INTO. This causes an error as it is trying to create a table that you have already created.

Either eliminate the CREATE TABLE statement or alter your query that fills it to use INSERT INTO SELECT format.

If you need a unique ID added to your new row then it's best to use SELECT INTO... since IDENTITY() only works with this syntax.

Android + Pair devices via bluetooth programmatically

In my first answer the logic is shown for those who want to go with the logic only.

I think I was not able to make clear to @chalukya3545, that's why I am adding the whole code to let him know the exact flow of the code.

public class BluetoothDemo extends Activity {

    ListView listViewPaired;
    ListView listViewDetected;
    ArrayList<String> arrayListpaired;
    Button buttonSearch,buttonOn,buttonDesc,buttonOff;
    ArrayAdapter<String> adapter,detectedAdapter;
    static HandleSeacrh handleSeacrh;
    BluetoothDevice bdDevice;
    BluetoothClass bdClass;
    ArrayList<BluetoothDevice> arrayListPairedBluetoothDevices;
    private ButtonClicked clicked;
    ListItemClickedonPaired listItemClickedonPaired;
    BluetoothAdapter bluetoothAdapter = null;
    ArrayList<BluetoothDevice> arrayListBluetoothDevices = null;
    ListItemClicked listItemClicked;

    public void onCreate(Bundle savedInstanceState) {
        listViewDetected = (ListView) findViewById(;
        listViewPaired = (ListView) findViewById(;
        buttonSearch = (Button) findViewById(;
        buttonOn = (Button) findViewById(;
        buttonDesc = (Button) findViewById(;
        buttonOff = (Button) findViewById(; 
        arrayListpaired = new ArrayList<String>();
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        clicked = new ButtonClicked();
        handleSeacrh = new HandleSeacrh();
        arrayListPairedBluetoothDevices = new ArrayList<BluetoothDevice>();
         * the above declaration is just for getting the paired bluetooth devices;
         * this helps in the removing the bond between paired devices.
        listItemClickedonPaired = new ListItemClickedonPaired();
        arrayListBluetoothDevices = new ArrayList<BluetoothDevice>();
        adapter= new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_1, arrayListpaired);
        detectedAdapter = new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_single_choice);
        listItemClicked = new ListItemClicked();

    protected void onStart() {
        // TODO Auto-generated method stub
    private void getPairedDevices() {
        Set<BluetoothDevice> pairedDevice = bluetoothAdapter.getBondedDevices();            
            for(BluetoothDevice device : pairedDevice)
    class ListItemClicked implements OnItemClickListener
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // TODO Auto-generated method stub
            bdDevice = arrayListBluetoothDevices.get(position);
            //bdClass = arrayListBluetoothDevices.get(position);
            Log.i("Log", "The dvice : "+bdDevice.toString());
             * here below we can do pairing without calling the callthread(), we can directly call the
             * connect(). but for the safer side we must usethe threading object.
            Boolean isBonded = false;
            try {
                isBonded = createBond(bdDevice);
            } catch (Exception e) {
            Log.i("Log", "The bond is created: "+isBonded);
    class ListItemClickedonPaired implements OnItemClickListener
        public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
            bdDevice = arrayListPairedBluetoothDevices.get(position);
            try {
                Boolean removeBonding = removeBond(bdDevice);

                Log.i("Log", "Removed"+removeBonding);
            } catch (Exception e) {
                // TODO Auto-generated catch block
    /*private void callThread() {
        new Thread(){
            public void run() {
                Boolean isBonded = false;
                try {
                    isBonded = createBond(bdDevice);
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                Log.i("Log", "The bond is created: "+isBonded);
    private Boolean connect(BluetoothDevice bdDevice) { 
        Boolean bool = false;
        try {
            Log.i("Log", "service method is called ");
            Class cl = Class.forName("android.bluetooth.BluetoothDevice");
            Class[] par = {};
            Method method = cl.getMethod("createBond", par);
            Object[] args = {};
            bool = (Boolean) method.invoke(bdDevice);//, args);// this invoke creates the detected devices paired.
            //Log.i("Log", "This is: "+bool.booleanValue());
            //Log.i("Log", "devicesss: "+bdDevice.getName());
        } catch (Exception e) {
            Log.i("Log", "Inside catch of serviceFromDevice Method");
        return bool.booleanValue();

    public boolean removeBond(BluetoothDevice btDevice)  
    throws Exception  
        Class btClass = Class.forName("android.bluetooth.BluetoothDevice");
        Method removeBondMethod = btClass.getMethod("removeBond");  
        Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);  
        return returnValue.booleanValue();  

    public boolean createBond(BluetoothDevice btDevice)  
    throws Exception  
        Class class1 = Class.forName("android.bluetooth.BluetoothDevice");
        Method createBondMethod = class1.getMethod("createBond");  
        Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);  
        return returnValue.booleanValue();  

    class ButtonClicked implements OnClickListener
        public void onClick(View view) {
            switch (view.getId()) {
    private BroadcastReceiver myReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            Message msg = Message.obtain();
            String action = intent.getAction();
                Toast.makeText(context, "ACTION_FOUND", Toast.LENGTH_SHORT).show();

                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    //device.getClass().getMethod("setPairingConfirmation", boolean.class).invoke(device, true);
                    //device.getClass().getMethod("cancelPairingUserInput", boolean.class).invoke(device);
                catch (Exception e) {
                    Log.i("Log", "Inside the exception: ");

                if(arrayListBluetoothDevices.size()<1) // this checks if the size of bluetooth device is 0,then add the
                {                                           // device to the arraylist.
                    boolean flag = true;    // flag to indicate that particular device is already in the arlist or not
                    for(int i = 0; i<arrayListBluetoothDevices.size();i++)
                            flag = false;
                    if(flag == true)
    private void startSearching() {
        Log.i("Log", "in the start searching method");
        IntentFilter intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        BluetoothDemo.this.registerReceiver(myReceiver, intentFilter);
    private void onBluetooth() {
            Log.i("Log", "Bluetooth is Enabled");
    private void offBluetooth() {
    private void makeDiscoverable() {
        Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
        discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
        Log.i("Log", "Discoverable ");
    class HandleSeacrh extends Handler
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 111:



Here is the main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:orientation="vertical" >

        android:text="Make Discoverable"/>
       android:text="Bluetooth Off"/>





Add this permissions to your AndroidManifest.xml file:

 <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
 <uses-permission android:name="android.permission.BLUETOOTH" />  
 <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

The output for this code will look like this. Bluutooth Demo

cvc-elt.1: Cannot find the declaration of element 'MyElement'

Your schema is for its target namespace so it defines an element with name MyElement in that target namespace Your instance document however has an element with name MyElement in no namespace. That is why the validating parser tells you it can't find a declaration for that element, you haven't provided a schema for elements in no namespace.

You either need to change the schema to not use a target namespace at all or you need to change the instance to use e.g. <MyElement xmlns="">A</MyElement>.

Why can I ping a server but not connect via SSH?

Find out two pieces of information

  • Whats the hostname or IP of the target ssh server
  • What port is the ssh daemon listening on (default is port 22)

$> telnet <hostname or ip> <port>

Assuming the daemon is up and running and listening on that port it should etablish a telnet session. Likely causes:

  • The ssh daemon is not running
  • The host is blocking the target port with its software firewall
  • Some intermediate network device is blocking or filtering the target port
  • The ssh daemon is listening on a non standard port
  • A TCP wrapper is configured and is filtering out your source host

Importing xsd into wsdl

import vs. include

The primary purpose of an import is to import a namespace. A more common use of the XSD import statement is to import a namespace which appears in another file. You might be gathering the namespace information from the file, but don't forget that it's the namespace that you're importing, not the file (don't confuse an import statement with an include statement).

Another area of confusion is how to specify the location or path of the included .xsd file: An XSD import statement has an optional attribute named schemaLocation but it is not necessary if the namespace of the import statement is at the same location (in the same file) as the import statement itself.

When you do chose to use an external .xsd file for your WSDL, the schemaLocation attribute becomes necessary. Be very sure that the namespace you use in the import statement is the same as the targetNamespace of the schema you are importing. That is, all 3 occurrences must be identical:


xs:import namespace="urn:listing3" schemaLocation="listing3.xsd"/>


<xsd:schema targetNamespace="urn:listing3"

Another approach to letting know the WSDL about the XSD is through Maven's pom.xml:


You can read more on this in this great IBM article. It has typos such as xsd:import instead of xs:import but otherwise it's fine.

How to convert image into byte array and byte array to base64 String in android?

Try this:

// convert from bitmap to byte array
public byte[] getBytesFromBitmap(Bitmap bitmap) {
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(CompressFormat.JPEG, 70, stream);
    return stream.toByteArray();

// get the base 64 string
String imgString = Base64.encodeToString(getBytesFromBitmap(someImg), 

configure: error: C compiler cannot create executables

If anyone is coming here because RVM / Ruby is creating issues (Middleman/Grunt) I've solved my issue.

PS. The answer by steroscott fixed my issue a while back...this time around not the case.

In my case rvm is trying to use a downloaded gcc via homebrew. I ran a brew uninstall of gcc (gcc46 for me) and reran the code for the ruby installation (old project old ruby v)

$ brew uninstall gcc46

$ rvm install 1.9.3

during that process of checking for requirements it automatically fetched a newer gcc for me and boom, all is working now. Oh a big note, the gcc install from the rvm command can take around 10-15 minutes without throwing out any text, it's not frozen :) Good luck

Download file inside WebView

Try using download manager, which can help you download everything you want and save you time.

Check those to options:

Option 1 ->

 mWebView.setDownloadListener(new DownloadListener() {
        public void onDownloadStart(String url, String userAgent,
                String contentDisposition, String mimetype,
                long contentLength) {
 Request request = new Request(
                    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download"); 
                    DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);


Option 2 ->

if(mWebview.getUrl().contains(".mp3") {
 Request request = new Request(
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download"); 
// You can change the name of the downloads, by changing "download" to everything you want, such as the mWebview title...
                DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);


Working with Enums in android

public enum Gender {

How to make an element in XML schema optional?

Set the minOccurs attribute to 0 in the schema like so:

<?xml version="1.0"?>
  <xs:schema version="1.0" xmlns:xs="" elementFormDefault="qualified">
    <xs:element name="request">
                <xs:element name="amenity">
                            <xs:element name="description" type="xs:string" minOccurs="0" />
    </xs:element> </xs:schema>

How to pass html string to webview on android

Passing null would be better. The full codes is like:

WebView wv = (WebView)this.findViewById(;
wv.loadDataWithBaseURL(null, "<html>...</html>", "text/html", "utf-8", null);

C# Iterate through Class properties

Yes, you could make an indexer on your Record class that maps from the property name to the correct property. This would keep all the binding from property name to property in one place eg:

public class Record
    public string ItemType { get; set; }

    public string this[string propertyName]
            switch (propertyName)
                case "itemType":
                    ItemType = value;
                    // etc

Alternatively, as others have mentioned, use reflection.

Configuring ObjectMapper in Spring

There is org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean for a long time. Starting from 1.2 release of Spring Boot there is org.springframework.http.converter.json.Jackson2ObjectMapperBuilder for Java Config.

In String Boot configuration can be as simple as:


in or some Java code in @Configuration class:

public Jackson2ObjectMapperBuilder jacksonBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.indentOutput(true).dateFormat(new SimpleDateFormat("yyyy-MM-dd"));
    return builder;


Unable to update the EntitySet - because it has a DefiningQuery and no <UpdateFunction> element exist

This is the case for me. Simply removing resulted in another error. I followed the steps of this post except the last one. For your convenience, I copied the 4 steps from the post that I followed to solve the problem as following:

  1. Right click on the edmx file, select Open with, XML editor
  2. Locate the entity in the edmx:StorageModels element
  3. Remove the DefiningQuery entirely
  4. Rename the store:Schema="dbo" to Schema="dbo" (otherwise, the code will generate an error saying the name is invalid)

JAXB :Need Namespace Prefix to all the elements

Another way is to tell the marshaller to always use a certain prefix

marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new NamespacePrefixMapper() {
            public String getPreferredPrefix(String arg0, String arg1, boolean arg2) {
                return "ns1";

Checking if a variable is initialized

If for instance you use strings instead of chars, you might be able do something like this:

    //a is a string of length 1
    string a;
    //b is the char in which we'll put the char stored in a
    char b;
    bool isInitialized(){
      if(a.length() != NULL){
        b = a[0];
        return true;
      }else return false;

Add "Appendix" before "A" in thesis TOC

You can easily achieve what you want using the appendix package. Here's a sample file that shows you how. The key is the titletoc option when calling the package. It takes whatever value you've defined in \appendixname and the default value is Appendix.


\chapter{Lorem ipsum}
\section{Dolor sit amet}
  \chapter{Consectetur adipiscing elit}
  \chapter{Mauris euismod}

The output looks like

enter image description here

Google Gson - deserialize list<class> object? (generic type)

In My case @uncaught_exceptions's answer didn't work, I had to use List.class instead of java.lang.reflect.Type:

String jsonDuplicatedItems = request.getSession().getAttribute("jsonDuplicatedItems").toString();
List<Map.Entry<Product, Integer>> entries = gson.fromJson(jsonDuplicatedItems, List.class);

javac error: Class names are only accepted if annotation processing is explicitly requested

I was stumped by this too because I was including the .Java extension ... then I noticed the capital J.

This will also cause the "annotation processing" error:

javac myclass.Java 

Instead, it should be:


Arithmetic operation resulted in an overflow. (Adding integers)

2055786000 + 93552000 = 2149338000, which is greater than 2^31. So if you're using signed integers coded on 4 bytes, the result of the operation doesn't fit and you get an overflow exception.

How to simulate a button click using code?

there is a better way.


this should answer all your problems. every View inherits this function, including Button, Spinner, etc.

Just to clarify, View does not have a static performClick() method. You must call performClick() on an instance of View. For example, you can't just call


Instead, do something like:

View myView = findViewById(;

Get Enum from Description attribute

The solution works good except if you have a Web Service.

You would need to do the Following as the Description Attribute is not serializable.

public enum ControlSelectionType
    [EnumMember(Value = "Not Applicable")]
    NotApplicable = 1,
    [EnumMember(Value = "Single Select Radio Buttons")]
    SingleSelectRadioButtons = 2,
    [EnumMember(Value = "Completely Different Display Text")]
    SingleSelectDropDownList = 3,

public static string GetDescriptionFromEnumValue(Enum value)
        EnumMemberAttribute attribute = value.GetType()
            .GetCustomAttributes(typeof(EnumMemberAttribute), false)
            .SingleOrDefault() as EnumMemberAttribute;
        return attribute == null ? value.ToString() : attribute.Value;

What exactly is OAuth (Open Authorization)?

OAuth is all about delegating Authorization (choosing someone who can do Authorization for you). Note that Authentication and Authorization are different things. OAuth is Authorization (Access control), and if you want to implement Authentication (ID verification) also, OpenID protocol can be used on top of OAuth.

All big companies like Facebook, Google, Github,... use this kind of authentication/authorization nowadays. For example, I just signed in on this website using my Google account, this means Stackoverflow doesn't know my password, it receives the allowance from Google where my password (hashed obviously) is saved. This gives a lot of benefits, one of them is; In the near future you won't have to make several accounts on every website. One website (which you trust most) can be used to login to all other websites. So you'll only have to remember one password.

Passing arguments to AsyncTask, and returning results

Why would you pass an ArrayList?? It should be possible to just call execute with the params directly:

String curloc = current.toString();
String itemdesc = item.mDescription;
new calc_stanica().execute(itemdesc, curloc)

That how varrargs work, right? Making an ArrayList to pass the variable is double work.

Simple conversion between java.util.Date and XMLGregorianCalendar

From XMLGregorianCalendar to java.util.Date you can simply do:

java.util.Date dt = xmlGregorianCalendarInstance.toGregorianCalendar().getTime();  

How to Load RSA Private Key From File

You need to convert your private key to PKCS8 format using following command:

openssl pkcs8 -topk8 -inform PEM -outform DER -in private_key_file  -nocrypt > pkcs8_key

After this your java program can read it.

Custom Drawable for ProgressBar/ProgressDialog

I'm not sure but in this case you can still go with a complete customized AlertDialog by having a seperate layout file set in the alert dialog and set the animation for your imageview using part of your above code that should also do it!

How to get C# Enum description from value?


The Unconstrained Melody library is no longer maintained; Support was dropped in favour of Enums.NET.

In Enums.NET you'd use:

string description = ((MyEnum)value).AsString(EnumFormat.Description);

Original post

I implemented this in a generic, type-safe way in Unconstrained Melody - you'd use:

string description = Enums.GetDescription((MyEnum)value);


  • Ensures (with generic type constraints) that the value really is an enum value
  • Avoids the boxing in your current solution
  • Caches all the descriptions to avoid using reflection on every call
  • Has a bunch of other methods, including the ability to parse the value from the description

I realise the core answer was just the cast from an int to MyEnum, but if you're doing a lot of enum work it's worth thinking about using Unconstrained Melody :)

The remote server returned an error: (407) Proxy Authentication Required

HttpWebRequest webRequest = WebRequest.Create(uirTradeStream) as HttpWebRequest;

webRequest.Proxy = WebRequest.DefaultWebProxy;

webRequest.Credentials = new NetworkCredential("user", "password");

webRequest.Proxy.Credentials = new NetworkCredential("user", "password");

It is successful.

Android TextView Text not getting wrapped

Increase the height i.e.. android:height="Some size" , it is working fine for me.

How to make a smooth image rotation in Android?

No matter what I tried, I couldn't get this to work right using code (and setRotation) for smooth rotation animation. What I ended up doing was making the degree changes so small, that the small pauses are unnoticeable. If you don't need to do too many rotations, the time to execute this loop is negligible. The effect is a smooth rotation:

        float lastDegree = 0.0f;
        float increment = 4.0f;
        long moveDuration = 10;
        for(int a = 0; a < 150; a++)
            rAnim = new RotateAnimation(lastDegree, (increment * (float)a),  Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
            rAnim.setStartOffset(moveDuration * a);
            lastDegree = (increment * (float)a);
            ((AnimationSet) animation).addAnimation(rAnim);

What does elementFormDefault do in XSD?

I have noticed that XMLSpy(at least 2011 version)needs a targetNameSpace defined if elementFormDefault="qualified" is used. Otherwise won't validate. And also won't generate xmls with namespace prefixes

Java substring: 'string index out of range'

You must check the String length. You assume that you can do substring(0,38) as long as String is not null, but you actually need the String to be of at least 38 characters length.

Is it possible to specify proxy credentials in your web.config?

Directory Services/LDAP lookups can be used to serve this purpose. It involves some changes at infrastructure level, but most production environments have such provision

BeanFactory not initialized or already closed - call 'refresh' before

The issue here is that the version of spring-web that you're using (3.1.1-RELEASE) is not compatible with the version of spring-beans that you're using (3.0.2-RELEASE). At the top of the stack you can see the NoSuchMethodError which in turn triggers the BeanFactory not initialized... exception.

The NoSuchMethodError is caused because the method invocation XmlWebApplicationContext.loadBeanDefinitions() in spring-web is trying to call XmlBeanDefinitionReader.setEnvironment() in spring-beans which doesn't exist in 3.0.2-RELEASE. It does however exist in 3.1.1-RELEASE - as setEnvironment is inherited from the parent AbstractBeanDefinitionReader.

To resolve, you'd probably be best to upgrade the spring-beans jar to 3.1.1-RELEASE. The version for this jar appears to be parameterized in your pom.xml and is controlled by the property org.springframework.version further down in the file.

Angular 2 optional route parameter

{path: 'users', redirectTo: 'users/', pathMatch: 'full'},
{path: 'users/:userId', component: UserComponent}

This way the component isn't re-rendered when the parameter is added.

Catch Ctrl-C in C

Addendum regarding UN*X platforms.

According to the signal(2) man page on GNU/Linux, the behavior of signal is not as portable as behavior of sigaction:

The behavior of signal() varies across UNIX versions, and has also varied historically across different versions of Linux. Avoid its use: use sigaction(2) instead.

On System V, system did not block delivery of further instances of the signal and delivery of a signal would reset the handler to the default one. In BSD the semantics changed.

The following variation of previous answer by Dirk Eddelbuettel uses sigaction instead of signal:

#include <signal.h>
#include <stdlib.h>

static bool keepRunning = true;

void intHandler(int) {
    keepRunning = false;

int main(int argc, char *argv[]) {
    struct sigaction act;
    act.sa_handler = intHandler;
    sigaction(SIGINT, &act, NULL);

    while (keepRunning) {
        // main loop

grep using a character vector with multiple patterns

To add to Brian Diggs answer.

another way using grepl will return a data frame containing all your values.

toMatch <- myfile$Letter

matches <- myfile[grepl(paste(toMatch, collapse="|"), myfile$Letter), ]


Letter Firstname
1     A1      Alex 
2     A6      Alex 
4     A1       Bob 
5     A9     Chris 
6     A6     Chris

Maybe a bit cleaner... maybe?

How to remove leading zeros from alphanumeric text?

I made some benchmark tests and found, that the fastest way (by far) is this solution:

    private static String removeLeadingZeros(String s) {
      try {
          Integer intVal = Integer.parseInt(s);
          s = intVal.toString();
      } catch (Exception ex) {
          // whatever
      return s;

Especially regular expressions are very slow in a long iteration. (I needed to find out the fastest way for a batchjob.)

Set space between divs

You need a gutter between two div gutter can be made as following

margin(gutter) = width - gutter size E.g margin = calc(70% - 2em)

<body bgcolor="gray">
<section id="main">
        <div id="left">
            Something here     
        <div id="right">
                Someone there
    font-size: 10px;

#main div{
    float: left;
    width: calc(50% - 1.5em);
    margin-left: 1.5em;

Can scrapy be used to scrape dynamic content from websites that are using AJAX?

Many times when crawling we run into problems where content that is rendered on the page is generated with Javascript and therefore scrapy is unable to crawl for it (eg. ajax requests, jQuery craziness).

However, if you use Scrapy along with the web testing framework Selenium then we are able to crawl anything displayed in a normal web browser.

Some things to note:

  • You must have the Python version of Selenium RC installed for this to work, and you must have set up Selenium properly. Also this is just a template crawler. You could get much crazier and more advanced with things but I just wanted to show the basic idea. As the code stands now you will be doing two requests for any given url. One request is made by Scrapy and the other is made by Selenium. I am sure there are ways around this so that you could possibly just make Selenium do the one and only request but I did not bother to implement that and by doing two requests you get to crawl the page with Scrapy too.

  • This is quite powerful because now you have the entire rendered DOM available for you to crawl and you can still use all the nice crawling features in Scrapy. This will make for slower crawling of course but depending on how much you need the rendered DOM it might be worth the wait.

    from scrapy.contrib.spiders import CrawlSpider, Rule
    from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor
    from scrapy.selector import HtmlXPathSelector
    from scrapy.http import Request
    from selenium import selenium
    class SeleniumSpider(CrawlSpider):
        name = "SeleniumSpider"
        start_urls = [""]
        rules = (
            Rule(SgmlLinkExtractor(allow=('\.html', )), callback='parse_page',follow=True),
        def __init__(self):
            self.verificationErrors = []
            self.selenium = selenium("localhost", 4444, "*chrome", "")
        def __del__(self):
            print self.verificationErrors
        def parse_page(self, response):
            item = Item()
            hxs = HtmlXPathSelector(response)
            #Do some XPath selection with Scrapy
            sel = self.selenium
            #Wait for javscript to load in Selenium
            #Do some crawling of javascript created content with Selenium
            yield item
    # Snippet imported from (which no longer works)
    # author: wynbennett
    # date  : Jun 21, 2011


How do I detect IE 8 with jQuery?

If you fiddle with browser versions it leads to no good very often. You don't want to implement it by yourself. But you can Modernizr made by Paul Irish and other smart folks. It will detect what the browser actually can do and put apropriate classes in <html> element. However with Modernizr, you can test IE version like this:

$('').each() {
    // this will execute if browser is IE 8 or less

Similary, you can use .lt-ie8, and .lt-ie7.

Is there a version of JavaScript's String.indexOf() that allows for regular expressions?

RexExp instances have a lastIndex property already (if they are global) and so what I'm doing is copying the regular expression, modifying it slightly to suit our purposes, exec-ing it on the string and looking at the lastIndex. This will inevitably be faster than looping on the string. (You have enough examples of how to put this onto the string prototype, right?)

function reIndexOf(reIn, str, startIndex) {
    var re = new RegExp(reIn.source, 'g' + (reIn.ignoreCase ? 'i' : '') + (reIn.multiLine ? 'm' : ''));
    re.lastIndex = startIndex || 0;
    var res = re.exec(str);
    if(!res) return -1;
    return re.lastIndex - res[0].length;

function reLastIndexOf(reIn, str, startIndex) {
    var src = /\$$/.test(reIn.source) && !/\\\$$/.test(reIn.source) ? reIn.source : reIn.source + '(?![\\S\\s]*' + reIn.source + ')';
    var re = new RegExp(src, 'g' + (reIn.ignoreCase ? 'i' : '') + (reIn.multiLine ? 'm' : ''));
    re.lastIndex = startIndex || 0;
    var res = re.exec(str);
    if(!res) return -1;
    return re.lastIndex - res[0].length;

reIndexOf(/[abc]/, "tommy can eat");  // Returns 6
reIndexOf(/[abc]/, "tommy can eat", 8);  // Returns 11
reLastIndexOf(/[abc]/, "tommy can eat"); // Returns 11

You could also prototype the functions onto the RegExp object:

RegExp.prototype.indexOf = function(str, startIndex) {
    var re = new RegExp(this.source, 'g' + (this.ignoreCase ? 'i' : '') + (this.multiLine ? 'm' : ''));
    re.lastIndex = startIndex || 0;
    var res = re.exec(str);
    if(!res) return -1;
    return re.lastIndex - res[0].length;

RegExp.prototype.lastIndexOf = function(str, startIndex) {
    var src = /\$$/.test(this.source) && !/\\\$$/.test(this.source) ? this.source : this.source + '(?![\\S\\s]*' + this.source + ')';
    var re = new RegExp(src, 'g' + (this.ignoreCase ? 'i' : '') + (this.multiLine ? 'm' : ''));
    re.lastIndex = startIndex || 0;
    var res = re.exec(str);
    if(!res) return -1;
    return re.lastIndex - res[0].length;

/[abc]/.indexOf("tommy can eat");  // Returns 6
/[abc]/.indexOf("tommy can eat", 8);  // Returns 11
/[abc]/.lastIndexOf("tommy can eat"); // Returns 11

A quick explanation of how I am modifying the RegExp: For indexOf I just have to ensure that the global flag is set. For lastIndexOf of I am using a negative look-ahead to find the last occurrence unless the RegExp was already matching at the end of the string.

jQuery detect if textarea is empty

This will check for empty textarea as well as will not allow only Spaces in textarea coz that looks empty too.

 var txt_msg = $("textarea").val();

 if (txt_msg.replace(/^\s+|\s+$/g, "").length == 0 || txt_msg=="") {
    return false;

php execute a background process

I am heavily using fast_cgi_finish_request()

In combination with a closure and register_shutdown_function()

$message ='job executed';
$backgroundJob = function() use ($message) {
     //do some work here
    echo $message;

Then register this closure to be executed before shutdown.


Finally when the response was sent to the client you can close the connection to the client and continue working with the PHP process:


The closure will be executed after fast_cgi_finish_request.

The $message will not be visible at any time. And you can register as much closures as you want, but take care about script execution time. This will only work if PHP is running as a Fast CGI module (was that right?!)

Can PHP cURL retrieve response headers AND body in a single request?

Try this if you are using GET:

$curl = curl_init($url);

curl_setopt_array($curl, array(
    CURLOPT_URL => $url,
        "Cache-Control: no-cache"

$response = curl_exec($curl);

Extend a java class from one file in another java file

Just put the two files in the same directory. Here's an example:

public class Person {
  public String name;

  public Person(String name) { = name;

  public String toString() {
    return name;

public class Student extends Person {
  public String somethingnew;

  public Student(String name) {
    somethingnew = "surprise!";

  public String toString() {
    return super.toString() + "\t" + somethingnew;

  public static void main(String[] args) {
    Person you = new Person("foo");
    Student me = new Student("boo");

    System.out.println("Your name is " + you);
    System.out.println("My name is " + me);

Running Student (since it has the main function) yields us the desired outcome:

Your name is foo
My name is boo  surprise!

How to convert Strings to and from UTF8 byte arrays in Java

I can't comment but don't want to start a new thread. But this isn't working. A simple round trip:

byte[] b = new byte[]{ 0, 0, 0, -127 };  // 0x00000081
String s = new String(b,StandardCharsets.UTF_8); // UTF8 = 0x0000, 0x0000,  0x0000, 0xfffd
b = s.getBytes(StandardCharsets.UTF_8); // [0, 0, 0, -17, -65, -67] 0x000000efbfbd != 0x00000081

I'd need b[] the same array before and after encoding which it isn't (this referrers to the first answer).

How to create an ArrayList from an Array in PowerShell?

Probably the shortest version:


It is also faster because it does not call relatively expensive New-Object.

How to generate class diagram from project in Visual Studio 2013?

Right click on the project in solution explorer or class view window --> "View" --> "View Class Diagram"

Clearing localStorage in javascript?

If you want to clear all item you stored in localStorage then


Use this for clear all stored key.

If you want to clear/remove only specific key/value then you can use removeItem(key).


MySQL - Using If Then Else in MySQL UPDATE or SELECT Queries

UPDATE table
SET A = IF(A > 0 AND A < 1, 1, IF(A > 1 AND A < 2, 2, A))

you might want to use CEIL() if A is always a floating point value > 0 and <= 2

MySQL query to get column names?

I have tried this query in SQL Server and this worked for me :

SELECT name FROM sys.columns WHERE OBJECT_ID = OBJECT_ID('table_name')

Concatenation of strings in Lua

As other answers have said, the string concatenation operator in Lua is two dots.

Your simple example would be written like this:

filename = "checkbook"
filename = filename .. ".tmp"

However, there is a caveat to be aware of. Since strings in Lua are immutable, each concatenation creates a new string object and copies the data from the source strings to it. That makes successive concatenations to a single string have very poor performance.

The Lua idiom for this case is something like this:

function listvalues(s)
    local t = { }
    for k,v in ipairs(s) do
        t[#t+1] = tostring(v)
    return table.concat(t,"\n")

By collecting the strings to be concatenated in an array t, the standard library routine table.concat can be used to concatenate them all up (along with a separator string between each pair) without unnecessary string copying.

Update: I just noticed that I originally wrote the code snippet above using pairs() instead of ipairs().

As originally written, the function listvalues() would indeed produce every value from the table passed in, but not in a stable or predictable order. On the other hand, it would include values who's keys were not positive integers in the span of 1 to #s. That is what pairs() does: it produces every single (key,value) pair stored in the table.

In most cases where you would be using something like listvaluas() you would be interested in preserving their order. So a call written as listvalues{13, 42, 17, 4} would produce a string containing those value in that order. However, pairs() won't do that, it will itemize them in some order that depends on the underlying implementation of the table data structure. It is known that the order not only depends on the keys, but also on the order in which the keys were inserted and other keys removed.

Of course ipairs() isn't a perfect answer either. It only enumerates those values of the table that form a "sequence". That is, those values who's keys form an unbroken block spanning from 1 to some upper bound, which is (usually) also the value returned by the # operator. (In many cases, the function ipairs() itself is better replaced by a simpler for loop that just counts from 1 to #s. This is the recommended practice in Lua 5.2 and in LuaJIT where the simpler for loop can be more efficiently implemented than the ipairs() iterator.)

If pairs() really is the right approach, then it is usually the case that you want to print both the key and the value. This reduces the concerns about order by making the data self-describing. Of course, since any Lua type (except nil and the floating point NaN) can be used as a key (and NaN can also be stored as a value) finding a string representation is left as an exercise for the student. And don't forget about trees and more complex structures of tables.

Support for "border-radius" in IE

<!DOCTYPE html> without this tag border-radius doesn't works in IE9, no need of meta tags.

Finding the number of days between two dates

echo $diff->format("%R%a days");

used the above code very simple. Thanks.

Convert Text to Date?

You can quickly convert a column of text that resembles dates into actual dates with the VBA equivalent of the worksheet's Data ? Text-to-Columns command.

With ActiveSheet.UsedRange.Columns("A").Cells
    .TextToColumns Destination:=.Cells(1), DataType:=xlFixedWidth, FieldInfo:=Array(0, xlYMDFormat)
    .NumberFormat = "yyyy-mm-dd"   'change to any date-based number format you prefer the cells to display
End With

Bulk operations are generally much quicker than looping through cells and the VBA's Range.TextToColumns method is very quick. It also allows you the freedom to set a MDY vs. DMY or YMD conversion mask that plagues many text imports where the date format does not match the system's regional settings. See TextFileColumnDataTypes property for a complete list of the available date formats available.

Caveat: Be careful when importing text that some of the dates have not already been converted. A text-based date with ambiguous month and day integers may already been converted wrongly; e.g. 07/11/2015 may have been interpreted as 07-Nov-2015 or 11-Jul-2015 depending upon system regional settings. In cases like this, abandon the import and bring the text back in with Data ? Get External Data ? From Text and specify the correct date conversion mask in the Text Import wizard. In VBA, use the Workbooks.OpenText method and specify the xlColumnDataType.

adding and removing classes in angularJs using ng-click

for Reactive forms -

HTML file

<div class="col-sm-2">_x000D_
  <button type="button"  [class]= "btn_class"  id="b1" (click)="changeMe()">{{ btn_label }}</button>_x000D_

TS file

changeMe() {_x000D_
  switch (this.btn_label) {_x000D_
    case 'Yes ': this.btn_label = 'Custom' ;_x000D_
    this.btn_class = 'btn btn-danger btn-lg btn-block';_x000D_
    case 'Custom': this.btn_label = ' No ' ;_x000D_
    this.btn_class = 'btn btn-success btn-lg btn-block';_x000D_
    case ' No ': this.btn_label = 'Yes ';_x000D_
      this.btn_class = 'btn btn-primary btn-lg btn-block';_x000D_

Why can't I do <img src="C:/localfile.jpg">?

I see two possibilities for what you are trying to do:

  1. You want your webpage, running on a server, to find the file on the computer that you originally designed it?

  2. You want it to fetch it from the pc that is viewing at the page?

Option 1 just doesn't make sense :)

Option 2 would be a security hole, the browser prohibits a web page (served from the web) from loading content on the viewer's machine.

Kyle Hudson told you what you need to do, but that is so basic that I find it hard to believe this is all you want to do.

Rails: FATAL - Peer authentication failed for user (PG::Error)

This is the most foolproof way to get your rails app working with postgres in the development environment in Ubuntu 13.10.

1) Create rails app with postgres YAML and 'pg' gem in the Gemfile:

$ rails new my_application -d postgresql

2) Give it some CRUD functionality. If you're just seeing if postgres works, create a scaffold:

$ rails g scaffold cats name:string age:integer colour:string

3) As of rails 4.0.1 the -d postgresql option generates a YAML that doesn't include a host parameter. I found I needed this. Edit the development section and create the following parameters:

encoding: UTF-8
host: localhost
database: my_application_development
username: thisismynewusername
password: thisismynewpassword 

Note the database parameter is for a database that doesn't exit yet, and the username and password are credentials for a role that doesn't exist either. We'll create those later on!

This is how config/database.yml should look (no shame in copypasting :D ):

  adapter: postgresql
  pool: 5
  # these are our new parameters
  encoding: UTF-8
  database: my_application_development
  host: localhost
  username: thisismynewusername
  password: thisismynewpassword

  # this won't work 
  adapter: postgresql
  encoding: unicode
  database: my_application_test
  pool: 5
  username: my_application

  # this won't work 
  adapter: postgresql
  encoding: unicode
  database: my_application_production
  pool: 5
  username: my_application

4) Start the postgres shell with this command:

$ psql

4a) You may get this error if your current user (as in your computer user) doesn't have a corresponding administration postgres role.

psql: FATAL:  role "your_username" does not exist

Now I've only installed postgres once, so I may be wrong here, but I think postgres automatically creates an administration role with the same credentials as the user you installed postgres as.

4b) So this means you need to change to the user that installed postgres to use the psql command and start the shell:

$ sudo su postgres

And then run

$ psql

5) You'll know you're in the postgres shell because your terminal will look like this:

$ psql
psql (9.1.10)
Type "help" for help.


6) Using the postgresql syntax, let's create the user we specified in config/database.yml's development section:

postgres=# CREATE ROLE thisismynewusername WITH LOGIN PASSWORD 'thisismynewpassword';

Now, there's some subtleties here so let's go over them.

  • The role's username, thisismynewusername, does not have quotes of any kind around it
  • Specify the keyword LOGIN after the WITH. If you don't, the role will still be created, but it won't be able to log in to the database!
  • The role's password, thisismynewpassword, needs to be in single quotes. Not double quotes.
  • Add a semi colon on the end ;)

You should see this in your terminal:


That means, "ROLE CREATED", but postgres' alerts seem to adopt the same imperative conventions of git hub.

7) Now, still in the postgres shell, we need to create the database with the name we set in the YAML. Make the user we created in step 6 its owner:

postgres=# CREATE DATABASE my_application_development OWNER thisismynewusername;

You'll know if you were successful because you'll get the output:


8) Quit the postgres shell:


9) Now the moment of truth:

$ RAILS_ENV=development rake db:migrate

If you get this:

==  CreateCats: migrating =================================================
-- create_table(:cats)
   -> 0.0028s
==  CreateCats: migrated (0.0028s) ========================================

Congratulations, postgres is working perfectly with your app.

9a) On my local machine, I kept getting a permission error. I can't remember it exactly, but it was an error along the lines of

Can't access the files. Change permissions to 666.

Though I'd advise thinking very carefully about recursively setting write privaledges on a production machine, locally, I gave my whole app read write privileges like this:

9b) Climb up one directory level:

$ cd ..

9c) Set the permissions of the my_application directory and all its contents to 666:

$ chmod -R 0666 my_application

9d) And run the migration again:

$ RAILS_ENV=development rake db:migrate

==  CreateCats: migrating =================================================
-- create_table(:cats)
   -> 0.0028s
==  CreateCats: migrated (0.0028s) ========================================

Some tips and tricks if you muck up

Try these before restarting all of these steps:

The mynewusername user doesn't have privileges to CRUD to the my_app_development database? Drop the database and create it again with mynewusername as the owner:

1) Start the postgres shell:

$ psql

2) Drop the my_app_development database. Be careful! Drop means utterly delete!

postgres=# DROP DATABASE my_app_development;

3) Recreate another my_app_development and make mynewusername the owner:

postgres=# CREATE DATABASE my_application_development OWNER mynewusername;

4) Quit the shell:

postgres=# \q

The mynewusername user can't log into the database? Think you wrote the wrong password in the YAML and can't quite remember the password you entered using the postgres shell? Simply alter the role with the YAML password:

1) Open up your YAML, and copy the password to your clipboard:

      adapter: postgresql
      pool: 5
      # these are our new parameters
      encoding: UTF-8
      database: my_application_development
      host: localhost
      username: thisismynewusername
      password: musthavebeenverydrunkwheniwrotethis

2) Start the postgres shell:

$ psql    

3) Update mynewusername's password. Paste in the password, and remember to put single quotes around it:

postgres=# ALTER ROLE mynewusername PASSWORD `musthavebeenverydrunkwheniwrotethis`;

4) Quit the shell:

postgres=# \q

Trying to connect to localhost via a database viewer such as Dbeaver, and don't know what your postgres user's password is? Change it like this:

1) Run passwd as a superuser:

$ sudo passwd postgres

2) Enter your accounts password for sudo (nothing to do with postgres):

[sudo] password for starkers: myaccountpassword

3) Create the postgres account's new passwod:

Enter new UNIX password: databasesarefun
Retype new UNIX password: databasesarefun
passwd: password updated successfully

Getting this error message?:

Run `$ bin/rake db:create db:migrate` to create your database
$ rake db:create db:migrate
PG::InsufficientPrivilege: ERROR:  permission denied to create database

4) You need to give your user the ability to create databases. From the psql shell:

ALTER ROLE thisismynewusername WITH CREATEDB

Are vectors passed to functions by value or by reference in C++

void foo(vector<int> test)

vector would be passed by value in this.

You have more ways to pass vectors depending on the context:-

1) Pass by reference:- This will let function foo change your contents of the vector. More efficient than pass by value as copying of vector is avoided.

2) Pass by const-reference:- This is efficient as well as reliable when you don't want function to change the contents of the vector.

How can Bash execute a command in a different directory context?

Use cd in a subshell; the shorthand way to use this kind of subshell is parentheses.

(cd wherever; mycommand ...)

That said, if your command has an environment that it requires, it should really ensure that environment itself instead of putting the onus on anything that might want to use it (unless it's an internal command used in very specific circumstances in the context of a well defined larger system, such that any caller already needs to ensure the environment it requires). Usually this would be some kind of shell script wrapper.

When is the init() function run?

init will be called everywhere uses its package(no matter blank import or import), but only one time.

this is a package:

package demo

import (

var count int

func init() {

// Do do
func Do() {

any package(main package or any test package) import it as blank :

_ ""

or import it using it func:


func someFunc(){

the init will log 0 only one time. the first package using it, its init func will run before the package's init. So:

A calls B, B calls C, all of them have init func, the C's init will be run first before B's, B's before A's.

How to add an item to an ArrayList in Kotlin?

You can add element to arrayList using add() method in Kotlin. For example,


Above code will add element 10 to arrayList.

However, if you are using Array or List, then you can not add element. This is because Array and List are Immutable. If you want to add element, you will have to use MutableList.

Several workarounds:

  1. Using System.arraycopy() method: You can achieve same target by creating new array and copying all the data from existing array into new one along with new values. This way you will have new array with all desired values(Existing and New values)
  2. Using MutableList:: Convert array into mutableList using toMutableList() method. Then, add element into it.
  3. Using Array.copyof(): Somewhat similar as System.arraycopy() method.

jQuery function to open link in new window

Button click event only.

<script src="//" type="text/javascript"></script>
        <script language="javascript" type="text/javascript">
            $(document).ready(function () {
                $("#btnext").click(function () {                    
          "HTMLPage.htm", "PopupWindow", "width=600,height=600,scrollbars=yes,resizable=no");

How can I list all foreign keys referencing a given table in SQL Server?

The original question asked to get a list of all foreign keys into a highly referenced table so that the table can be removed.

This little query returns all the 'drop foreign key' commands needed to drop all foreign keys into a particular table:

   'ALTER TABLE [''].['+referencingTable.Name+'] DROP CONSTRAINT ['']' '[DropCommand]'
FROM sys.foreign_key_columns fk
    JOIN sys.tables referencingTable ON fk.parent_object_id = referencingTable.object_id
    JOIN sys.schemas sch ON referencingTable.schema_id = sch.schema_id
    JOIN sys.objects foreignKey ON foreignKey.object_id = fk.constraint_object_id
    JOIN sys.tables referencedTable ON fk.referenced_object_id = referencedTable.object_id
WHERE = 'MyTableName'

Example output:

ALTER TABLE [dbo].[OtherTable1] DROP CONSTRAINT [FK_OtherTable1_MyTable]
ALTER TABLE [dbo].[OtherTable2] DROP CONSTRAINT [FK_OtherTable2_MyTable]

Omit the WHERE-clause to get the drop commands for all foreign keys in the current database.

Pandas DataFrame to List of Dictionaries

As an extension to John Galt's answer -

For the following DataFrame,

   customer  item1   item2   item3
0         1  apple    milk  tomato
1         2  water  orange  potato
2         3  juice   mango   chips

If you want to get a list of dictionaries including the index values, you can do something like,


Which outputs a dictionary of dictionaries where keys of the parent dictionary are index values. In this particular case,

{0: {'customer': 1, 'item1': 'apple', 'item2': 'milk', 'item3': 'tomato'},
 1: {'customer': 2, 'item1': 'water', 'item2': 'orange', 'item3': 'potato'},
 2: {'customer': 3, 'item1': 'juice', 'item2': 'mango', 'item3': 'chips'}}

How do I filter date range in DataTables?

Follow the link below and configure it to what you need. Daterangepicker does it for you, very easily. :)

Failed to load resource: the server responded with a status of 500 (Internal Server Error) in Bind function

The 500 code would normally indicate an error on the server, not anything with your code. Some thoughts

  • Talk to the server developer for more info. You can't get more info directly.
  • Verify your arguments into the call (values). Look for anything you might think could cause a problem for the server process. The process should not die and should return you a better code, but bugs happen there also.
  • Could be intermittent, like if the server database goes down. May be worth trying at another time.

How to count items in JSON data

import json

json_data = json.dumps({
      "find": "true"

item_dict = json.loads(json_data)
print len(item_dict['result'][0]['run'])

Convert it in dict.

how to get the first and last days of a given month

cal_days_in_month() should give you the total number of days in the month, and therefore, the last one.

How to get Rails.logger printing to the console/stdout when running rspec?

You can define a method in spec_helper.rb that sends a message both to and to puts and use that for debugging:

def log_test(message)
    puts message

Get full URL and query string in Servlet for both HTTP and HTTPS requests

Simply Use:

String Uri = request.getRequestURL()+"?"+request.getQueryString();

SQL: capitalize first letter only

Please check the query without using a function:

declare @T table(Insurance varchar(max))

insert into @T values ('wezembeek-oppem')
insert into @T values ('roeselare')
insert into @T values ('BRUGGE')
insert into @T values ('louvain-la-neuve')

select (
       select upper(T.N.value('.', 'char(1)'))+
                lower(stuff(T.N.value('.', 'varchar(max)'), 1, 1, ''))+(CASE WHEN RIGHT(T.N.value('.', 'varchar(max)'), 1)='-' THEN '' ELSE ' ' END)
       from X.InsXML.nodes('/N') as T(N)
       for xml path(''), type
       ).value('.', 'varchar(max)') as Insurance
  select cast('<N>'+replace(
                ' ', '</N><N>'),
            '-', '-</N><N>')+'</N>' as xml) as InsXML
  from @T
  ) as X

Set System.Drawing.Color values

You could create a color using the static FromArgb method:

Color redColor = Color.FromArgb(255, 0, 0);

You can also specify the alpha using the following overload.

move_uploaded_file gives "failed to open stream: Permission denied" error

Change permissions for this folder

# chmod -R 0755 /var/www/html/mysite/images/

How to install popper.js with Bootstrap 4? does not look like a right src for popper, it does not specify the file

with bootstrap 4 I am using this

<script src="" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>

and it is working perfectly fine, give it a try

"Series objects are mutable and cannot be hashed" error

gene_name = no_headers.iloc[1:,[1]]

This creates a DataFrame because you passed a list of columns (single, but still a list). When you later do this:


you now have a Series object with a single value. You can't hash the Series.

The solution is to create Series from the start.

gene_type = no_headers.iloc[1:,0]
gene_name = no_headers.iloc[1:,1]
disease_name = no_headers.iloc[1:,2]

Also, where you have orph_dict[gene_name[x]] =+ 1, I'm guessing that's a typo and you really mean orph_dict[gene_name[x]] += 1 to increment the counter.

Facebook database design?

My best bet is that they created a graph structure. The nodes are users and "friendships" are edges.

Keep one table of users, keep another table of edges. Then you can keep data about the edges, like "day they became friends" and "approved status," etc.

Map and Reduce in .NET

Linq equivalents of Map and Reduce: If you’re lucky enough to have linq then you don’t need to write your own map and reduce functions. C# 3.5 and Linq already has it albeit under different names.

  • Map is Select:

    Enumerable.Range(1, 10).Select(x => x + 2);
  • Reduce is Aggregate:

    Enumerable.Range(1, 10).Aggregate(0, (acc, x) => acc + x);
  • Filter is Where:

    Enumerable.Range(1, 10).Where(x => x % 2 == 0);

C++ "Access violation reading location" Error

Vertex *f=(findvertex(from));
if(!f) {
    cerr << "vertex not found" << endl;
    exit(1) // or return;

Because findVertex can return NULL if it can't find the vertex.

Otherwise this f->adj; is trying to do


Which causes access violation.

PHP post_max_size overrides upload_max_filesize


  • Sets max size of post data allowed. This setting also affects file upload
  • To upload large files, this value must be larger than upload_max_filesize
  • Generally speaking, memory_limit should be larger than post_max_size.
  • PHP Default: 8M


  • The maximum size of an uploaded file
  • PHP Default: 2M

memory_limit > post_max_size > upload_max_filesize

PHP Default: 128M > 8M > 2M

By default, post_max_size should be 4 times greater than upload_max_filesize.
In turn memory_limit should be 16 times greater than post_max_size

Selecting only first-level elements in jquery

As stated in other answers, the simplest method is to uniquely identify the root element (by ID or class name) and use the direct descendent selector.

$('ul.topMenu > li > a')

However, I came across this question in search of a solution which would work on unnamed elements at varying depths of the DOM.

This can be achieved by checking each element, and ensuring it does not have a parent in the list of matched elements. Here is my solution, wrapped in a jQuery selector 'topmost'.

jQuery.extend(jQuery.expr[':'], {
  topmost: function (e, index, match, array) {
    for (var i = 0; i < array.length; i++) {
      if (array[i] !== false && $(e).parents().index(array[i]) >= 0) {
        return false;
    return true;

Utilizing this, the solution to the original post is:

$('ul:topmost > li > a')

// Or, more simply:
$('li:topmost > a')

Complete jsFiddle available here.

invalid types 'int[int]' for array subscript

Just for completeness, this error can happen also in a different situation: when you declare an array in an outer scope, but declare another variable with the same name in an inner scope, shadowing the array. Then, when you try to index the array, you are actually accessing the variable in the inner scope, which might not even be an array, or it might be an array with fewer dimensions.


int a[10];  // a global scope

void f(int a)   // a declared in local scope, overshadows a in global scope
  printf("%d", a[0]);  // you trying to access the array a, but actually addressing local argument a

Overflow:hidden dots at the end

Hopefully it's helpful for you:

.text-with-dots {_x000D_
    display: block;_x000D_
    max-width: 98%;_x000D_
    white-space: nowrap;_x000D_
    overflow: hidden !important;_x000D_
    text-overflow: ellipsis;_x000D_
<div class='text-with-dots'>Some texts here Some texts here Some texts here Some texts here Some texts here Some texts here </div>

Add colorbar to existing axis

This technique is usually used for multiple axis in a figure. In this context it is often required to have a colorbar that corresponds in size with the result from imshow. This can be achieved easily with the axes grid tool kit:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable

data = np.arange(100, 0, -1).reshape(10, 10)

fig, ax = plt.subplots()
divider = make_axes_locatable(ax)
cax = divider.append_axes('right', size='5%', pad=0.05)

im = ax.imshow(data, cmap='bone')

fig.colorbar(im, cax=cax, orientation='vertical')

Image with proper colorbar in size

How to run two jQuery animations simultaneously?

yes there is!

$(function () {
       width: '200px'
    }, { duration: 200, queue: false });

       width: '600px'
    }, { duration: 200, queue: false });

Stopping Docker containers by image name - Ubuntu

If you want to prefer a simple AWK approach, here Is my take:

docker rm -f $(docker ps | awk '{ if($2 == "<your image name>") { print $NF}}')

$(docker ps | awk '{ if($2 == "<your image name>") { print $NF}}') - prints the docker container names based on input image

docker ps - list all containers

awk '{ if($2 == "<your-image-name>") { print $NF}}' - The second parsed column of docker ps gives the image name. Comparing it with your image name will execute print $NF which prints the container name.

docker rm -f removes the containers

For example, removing all running containers of ubuntu image, can be done simply as:

docker rm -f $(docker ps | awk '{ if($2 == "ubuntu:latest") { print $NF}}')

PS: Remember to include the image tag in AWK, since it's a equal comparator.

Accessing elements by type in javascript

The sizzle selector engine (what powers JQuery) is perfectly geared up for this:

var elements = $('input[type=text]');


var elements = $('input:text');

Difference between a Seq and a List in Scala

Seq is a trait that List implements.

If you define your container as Seq, you can use any container that implements Seq trait.

scala> def sumUp(s: Seq[Int]): Int = { s.sum }
sumUp: (s: Seq[Int])Int

scala> sumUp(List(1,2,3))
res41: Int = 6

scala> sumUp(Vector(1,2,3))
res42: Int = 6

scala> sumUp(Seq(1,2,3))
res44: Int = 6

Note that

scala> val a = Seq(1,2,3)
a: Seq[Int] = List(1, 2, 3)

Is just a short hand for:

scala> val a: Seq[Int] = List(1,2,3)
a: Seq[Int] = List(1, 2, 3)

if the container type is not specified, the underlying data structure defaults to List.

'list' object has no attribute 'shape'

firstly u have to import numpy library (refer code for making a numpy array) shape only gives the output only if the variable is attribute of numpy library .in other words it must be a np.array or any other data structure of numpy. Eg.

`>>> import numpy
>>> a=numpy.array([[1,1],[1,1]])
>>> a.shape
(2, 2)`

Send message to specific client with and node.js

Whatever version we are using if we just console.log() the "io" object that we use in our server side nodejs code, [e.g. io.on('connection', function(socket) {...});], we can see that "io" is just an json object and there are many child objects where the socket id and socket objects are stored.

I am using version 1.3.5, btw.

If we look in the io object, it contains,

  { name: '/',
    server: [Circular],
    sockets: [ [Object], [Object] ],
     { B5AC9w0sYmOGWe4fAAAA: [Object],
       'hWzf97fmU-TIwwzWAAAB': [Object] },

here we can see the socketids "B5AC9w0sYmOGWe4fAAAA" etc. So, we can do,


Again, on further inspection we can see segments like,

  { clients:
     { B5AC9w0sYmOGWe4fAAAA: [Object],
       'hWzf97fmU-TIwwzWAAAB': [Object] },

So, we can retrieve a socket from here by doing


Also, under engine we have,

 { clients:
    { B5AC9w0sYmOGWe4fAAAA: [Object],
      'hWzf97fmU-TIwwzWAAAB': [Object] },

So, we can also write,


So, I guess we can achieve our goal in any of the 3 ways I listed above,

  1. io.sockets.connected[socketid].emit(); OR
  2. io.eio.clients[socketid].emit(); OR
  3. io.engine.clients[socketid].emit();

How does Spring autowire by name when more than one matching bean is found?

Another way of achieving the same result is to use the @Value annotation:

public class Main {
     private Country country;

     public void setCountry(@Value("#{country}") Country country) {
 = country;

In this case, the "#{country} string is an Spring Expression Language (SpEL) expression which evaluates to a bean named country.

What does "\r" do in the following script?

\r is the ASCII Carriage Return (CR) character.

There are different newline conventions used by different operating systems. The most common ones are:

  • CR+LF (\r\n);
  • LF (\n);
  • CR (\r).

The \n\r (LF+CR) looks unconventional.

edit: My reading of the Telnet RFC suggests that:

  1. CR+LF is the standard newline sequence used by the telnet protocol.
  2. LF+CR is an acceptable substitute:

The sequence "CR LF", as defined, will cause the NVT to be positioned at the left margin of the next print line (as would, for example, the sequence "LF CR").

Easy way to convert a unicode list to a list containing python strings?

We can use map function

print map(str, EmployeeList)

SQL Server: Importing database from .mdf?

See: How to: Attach a Database File to SQL Server Express

Login to the database via sqlcmd:

sqlcmd -S Server\Instance

And then issue the commands:

USE [master]
CREATE DATABASE [database_name] ON 
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Data\<database name>.mdf' ),
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Data\<database name>.ldf' )

Programmatically set left drawable in a TextView

Using Kotlin:

You can create an extension function or just use setCompoundDrawablesWithIntrinsicBounds directly.

fun TextView.leftDrawable(@DrawableRes id: Int = 0) {
   this.setCompoundDrawablesWithIntrinsicBounds(id, 0, 0, 0)

If you need to resize the drawable, you can use this extension function.

textView.leftDrawable(R.drawable.my_icon, R.dimen.icon_size)

fun TextView.leftDrawable(@DrawableRes id: Int = 0, @DimenRes sizeRes: Int) {
    val drawable = ContextCompat.getDrawable(context, id)
    val size = resources.getDimensionPixelSize(sizeRes)
    drawable?.setBounds(0, 0, size, size)
    this.setCompoundDrawables(drawable, null, null, null)

To get really fancy, create a wrapper that allows size and/or color modification.

textView.leftDrawable(R.drawable.my_icon, colorRes = R.color.white)

fun TextView.leftDrawable(@DrawableRes id: Int = 0, @DimenRes sizeRes: Int = 0, @ColorInt color: Int = 0, @ColorRes colorRes: Int = 0) {
    val drawable = drawable(id)
    if (sizeRes != 0) {
        val size = resources.getDimensionPixelSize(sizeRes)
        drawable?.setBounds(0, 0, size, size)
    if (color != 0) {
        drawable?.setColorFilter(color, PorterDuff.Mode.SRC_ATOP)
    } else if (colorRes != 0) {
        val colorInt = ContextCompat.getColor(context, colorRes)
        drawable?.setColorFilter(colorInt, PorterDuff.Mode.SRC_ATOP)
    this.setCompoundDrawables(drawable, null, null, null)

AngularJS : Factory and Service?

Factory and Service is a just wrapper of a provider.


Factory can return anything which can be a class(constructor function), instance of class, string, number or boolean. If you return a constructor function, you can instantiate in your controller.

 myApp.factory('myFactory', function () {

  // any logic here..

  // Return any thing. Here it is object
  return {
    name: 'Joe'


Service does not need to return anything. But you have to assign everything in this variable. Because service will create instance by default and use that as a base object.

myApp.service('myService', function () {

  // any logic here.. = 'Joe';

Actual angularjs code behind the service

function service(name, constructor) {
    return factory(name, ['$injector', function($injector) {
        return $injector.instantiate(constructor);

It just a wrapper around the factory. If you return something from service, then it will behave like Factory.

IMPORTANT: The return result from Factory and Service will be cache and same will be returned for all controllers.

When should i use them?

Factory is mostly preferable in all cases. It can be used when you have constructor function which needs to be instantiated in different controllers.

Service is a kind of Singleton Object. The Object return from Service will be same for all controller. It can be used when you want to have single object for entire application. Eg: Authenticated user details.

For further understanding, read

mysqldump with create database line

By default mysqldump always creates the CREATE DATABASE IF NOT EXISTS db_name; statement at the beginning of the dump file.

[EDIT] Few things about the mysqldump file and it's options:

--all-databases, -A

Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.


Add a DROP DATABASE statement before each CREATE DATABASE statement. This option is typically used in conjunction with the --all-databases or --databases option because no CREATE DATABASE statements are written unless one of those options is specified.

--databases, -B

Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.

--no-create-db, -n

This option suppresses the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.

Some time ago, there was similar question actually asking about not having such statement on the beginning of the file (for XML file). Link to that question is here.

So to answer your question:

  • if you have one database to dump, you should have the --add-drop-database option in your mysqldump statement.
  • if you have multiple databases to dump, you should use the option --databases or --all-databases and the CREATE DATABASE syntax will be added automatically

More information at MySQL Reference Manual

open new tab(window) by clicking a link in jquery

Try this:, '_blank');

This will open in new tab (if your code is synchronous and in this case it is. in other case it would open a window)

port forwarding in windows

I've solved it, it can be done executing:

netsh interface portproxy add v4tov4 listenport=4422 listenaddress= connectport=80 connectaddress=

To remove forwarding:

netsh interface portproxy delete v4tov4 listenport=4422 listenaddress=

Official docs

OpenCV Error: (-215)size.width>0 && size.height>0 in function imshow

In these two lines:

mask = cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2)

frame =,(a, b),5,color[i].tolist(),-1)

try instead:

cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2),(a, b),5,color[i].tolist(),-1)

I had the same problem and the variables were being returned empty

How to set default value to the input[type="date"]

The date should take the format YYYY-MM-DD. Single digit days and months should be padded with a 0. January is 01.

From the documentation:

A string representing a date.

Value: A valid full-date as defined in [RFC 3339], with the additional qualification that the year component is four or more digits representing a number greater than 0.

Your code should be altered to:

<input type="date" value="2013-01-08">

Example jsfiddle

How do you split a list into evenly sized chunks?

letting r be the chunk size and L be the initial list, you can do.

chunkL = [ [i for i in L[r*k:r*(k+1)] ] for k in range(len(L)/r)] 

Can you change what a symlink points to after it is created?

AFAIK, no, you can't. You have to remove it and recreate it. Actually, you can overwrite a symlink and thus update the pathname referenced by it:

$ ln -s .bashrc test
$ ls -al test
lrwxrwxrwx 1 pascal pascal 7 2009-09-23 17:12 test -> .bashrc
$ ln -s .profile test
ln: creating symbolic link `test': File exists
$ ln -s -f .profile test
$ ls -al test
lrwxrwxrwx 1 pascal pascal 8 2009-09-23 17:12 test -> .profile

EDIT: As the OP pointed out in a comment, using the --force option will make ln perform a system call to unlink() before symlink(). Below, the output of strace on my linux box proving it:

$ strace -o /tmp/output.txt ln -s -f .bash_aliases test
$ grep -C3 ^unlink /tmp/output.txt 
lstat64("test", {st_mode=S_IFLNK|0777, st_size=7, ...}) = 0
stat64(".bash_aliases", {st_mode=S_IFREG|0644, st_size=2043, ...}) = 0
symlink(".bash_aliases", "test")        = -1 EEXIST (File exists)
unlink("test")                          = 0
symlink(".bash_aliases", "test")        = 0
close(0)                                = 0
close(1)                                = 0

So I guess the final answer is "no".

EDIT: The following is copied from Arto Bendiken's answer over on, circa 2016.

This can indeed be done atomically with rename(2), by first creating the new symlink under a temporary name and then cleanly overwriting the old symlink in one go. As the man page states:

If newpath refers to a symbolic link the link will be overwritten.

In the shell, you would do this with mv -T as follows:

$ mkdir a b
$ ln -s a z
$ ln -s b
$ mv -T z

You can strace that last command to make sure it is indeed using rename(2) under the hood:

$ strace mv -T z
lstat64("", {st_mode=S_IFLNK|0777, st_size=1, ...}) = 0
lstat64("z", {st_mode=S_IFLNK|0777, st_size=1, ...}) = 0
rename("", "z")                    = 0

Note that in the above, both mv -T and strace are Linux-specific.

On FreeBSD, use mv -h alternately.

Editor's note: This is how Capistrano has done it for years now, ever since ~2.15. See this pull request.

How to get the path of src/test/resources directory in JUnit?

All content in src/test/resources is copied into target/test-classes folder. So to get file from test resources during maven build you have to load it from test-classes folder, like that:


Break down:

  1. getClass().getProtectionDomain().getCodeSource().getLocation().toURI() - give you URI to target/test-classes.
  2. resolve(Paths.get("somefile")) - resolves someFile to target/test-classes folder.

Original anwser is taken from this

Python "expected an indented block"

in python .....intendation matters, e.g.:

if a==1:

if a==2:

print("all the best")

In this case "all the best" will be printed if either of the two conditions executes, but if it would have been like this

if a==2:
   print("all the best")

then "all the best" will be printed only if a==2

How to detect the character encoding of a text file?

I use Ude that is a C# port of Mozilla Universal Charset Detector. It is easy to use and gives some really good results.

document.createElement("script") synchronously

This looks like a decent overview of dynamic script loading:

Can't push to remote branch, cannot be resolved to branch

I was having this issue as well, and it was driving me crazy. I had something like feature/name but git branch -a showed me FEATURE/name. Renaming the branch, deleting and recreating it, nothing worked. What finally fixed it:

Go into .git/refs/heads

You'll see a FEATURE folder. Rename it to feature.

How to overwrite the previous print to stdout in python?

The accepted answer is not perfect. The line that was printed first will stay there and if your second print does not cover the entire new line, you will end up with garbage text.

To illustrate the problem save this code as a script and run it (or just take a look):

import time

n = 100
for i in range(100):
    for j in range(100):
        print("Progress {:2.1%}".format(j / 100), end="\r")
    print("Progress {:2.1%}".format(i / 100))

The output will look something like this:

Progress 0.0%%
Progress 1.0%%
Progress 2.0%%
Progress 3.0%%

What works for me is to clear the line before leaving a permanent print. Feel free to adjust to your specific problem:

import time

ERASE_LINE = '\x1b[2K' # erase line command
n = 100
for i in range(100):
    for j in range(100):
        print("Progress {:2.1%}".format(j / 100), end="\r")
    print(ERASE_LINE + "Progress {:2.1%}".format(i / 100)) # clear the line first

And now it prints as expected:

Progress 0.0%
Progress 1.0%
Progress 2.0%
Progress 3.0%

fatal: could not create work tree dir 'kivy'

You should do the command in a directory where you have write permission. So:

cd ~/
mkdir code
cd code
git clone

For example.

How to open an external file from HTML

You may need an extra "/"

<a href="file:///server/directory/file.xlsx">Click me!</a>

Align printf output in Java

A simple solution that springs to mind is to have a String block of spaces:

String indent = "                  "; // 20 spaces.

When printing out a string, compute the actual indent and add it to the end:

String output = "Newspaper";
output += indent.substring(0, indent.length - output.length);

This will mediate the number of spaces to the string, and put them all in the same column.

Cloning a private Github repo

I was using Android Studio to clone the project from GitHub private repository and two-factor authentication (2FA). I created a personal token as made in lzl124631x's answer.

Then I cloned the repo using an url like this: https://YourGitHubUsername:[email protected]/YourRepoPath.git

Shorten string without cutting words in JavaScript

Here's yet another piece of code that truncates along punctuation marks (was looking for this and Google found this question here). Had to come up with a solution on my own, so this is what I hacked in 15 minutes. Finds all occurrences of . ! ? and truncates at any position of these that's < than len

function pos(str, char) {
    let pos = 0
    const ret = []
    while ( (pos = str.indexOf(char, pos + 1)) != -1) {
    return ret

function truncate(str, len) {
    if (str.length < len)
        return str

    const allPos = [  ...pos(str, '!'), ...pos(str, '.'), ...pos(str, '?')].sort( (a,b) => a-b )
    if (allPos.length === 0) {
        return str.substr(0, len)

    for(let i = 0; i < allPos.length; i++) {
        if (allPos[i] > len) {
            return str.substr(0, allPos[i-1] + 1)

module.exports = truncate

app-release-unsigned.apk is not signed

For security reasons, you cannot install an unsigned apk on Android. So if you only have the unsigned apk: you must sign it. Here is how to do that : link

Note that you can sign the apk with a self-signed certificate.

An alternative can be either :

  • to download the signed apk if available.
  • to download the sources, compile them (with Android-Studio or gradle or ...). It will produce multiple apks and one of them will be signed with your debug-key (and so you will be able to install it)

IF EXISTS before INSERT, UPDATE, DELETE for optimization

There is a slight effect, since you're doing the same check twice, at least in your example:


Has to query, see if there are any, if true then:

UPDATE Contacs SET [Deleted] = 1 WHERE [Type] = 1

Has to query, see which ones...same check twice for no reason. Now if the condition you're looking for is indexed it ought to be quick, but for large tables you could see some delay just because you're running the select.

Spring RestTemplate timeout

I had a similar scenario, but was also required to set a Proxy. The simplest way I could see to do this was to extend the SimpleClientHttpRequestFactory for the ease of setting the proxy (different proxies for non-prod vs prod). This should still work even if you don't require the proxy though. Then in my extended class I override the openConnection(URL url, Proxy proxy) method, using the same as the source, but just setting the timeouts before returning.

protected HttpURLConnection openConnection(URL url, Proxy proxy) throws IOException {
    URLConnection urlConnection = proxy != null ? url.openConnection(proxy) : url.openConnection();
    Assert.isInstanceOf(HttpURLConnection.class, urlConnection);
    return (HttpURLConnection) urlConnection;

Countdown timer in React

Basic idea showing counting down using instead of subtracting one which will drift over time.

class Example extends React.Component {
  constructor() {
    this.state = {
      time: {
        hours: 0,
        minutes: 0,
        seconds: 0,
        milliseconds: 0,
      duration: 2 * 60 * 1000,
      timer: null
    this.startTimer = this.start.bind(this);

  msToTime(duration) {
    let milliseconds = parseInt((duration % 1000));
    let seconds = Math.floor((duration / 1000) % 60);
    let minutes = Math.floor((duration / (1000 * 60)) % 60);
    let hours = Math.floor((duration / (1000 * 60 * 60)) % 24);

    hours = hours.toString().padStart(2, '0');
    minutes = minutes.toString().padStart(2, '0');
    seconds = seconds.toString().padStart(2, '0');
    milliseconds = milliseconds.toString().padStart(3, '0');

    return {

  componentDidMount() {}

  start() {
    if (!this.state.timer) {
      this.state.startTime =;
      this.timer = window.setInterval(() =>, 10);

  run() {
    const diff = - this.state.startTime;
    // If you want to count up
    // this.setState(() => ({
    //  time: this.msToTime(diff)
    // }));
    // count down
    let remaining = this.state.duration - diff;
    if (remaining < 0) {
      remaining = 0;
    this.setState(() => ({
      time: this.msToTime(remaining)
    if (remaining === 0) {
      this.timer = null;

  render() {
    return ( <
      div >
      button onClick = {
      } > Start < /button> {
      }: {
      }: {
      }. {

ReactDOM.render( < Example / > , document.getElementById('View'));
<script src=""></script>
<script src=""></script>
<div id="View"></div>

Is there a "theirs" version of "git merge -s ours"?

Why doesn't it exist?

While I mention in "git command for making one branch like another" how to simulate git merge -s theirs, note that Git 2.15 (Q4 2017) is now clearer:

The documentation for '-X<option>' for merges was misleadingly written to suggest that "-s theirs" exists, which is not the case.

See commit c25d98b (25 Sep 2017) by Junio C Hamano (gitster).
(Merged by Junio C Hamano -- gitster -- in commit 4da3e23, 28 Sep 2017)

merge-strategies: avoid implying that "-s theirs" exists

The description of -Xours merge option has a parenthetical note that tells the readers that it is very different from -s ours, which is correct, but the description of -Xtheirs that follows it carelessly says "this is the opposite of ours", giving a false impression that the readers also need to be warned that it is very different from -s theirs, which in reality does not even exist.

-Xtheirs is a strategy option applied to recursive strategy. This means that recursive strategy will still merge anything it can, and will only fall back to "theirs" logic in case of conflicts.

That debate for the pertinence or not of a theirs merge strategy was brought back recently in this Sept. 2017 thread.
It acknowledges older (2008) threads

In short, the previous discussion can be summarized to "we don't want '-s theirs' as it encourages the wrong workflow".

It mentions the alias:

mtheirs = !sh -c 'git merge -s ours --no-commit $1 && git read-tree -m -u $1' -

Yaroslav Halchenko tries to advocate once more for that strategy, but Junio C. Hamano adds:

The reason why ours and theirs are not symmetric is because you are you and not them---the control and ownership of our history and their history is not symmetric.

Once you decide that their history is the mainline, you'd rather want to treat your line of development as a side branch and make a merge in that direction, i.e. the first parent of the resulting merge is a commit on their history and the second parent is the last bad one of your history. So you would end up using "checkout their-history && merge -s ours your-history" to keep the first-parenthood sensible.

And at that point, use of "-s ours" is no longer a workaround for lack of "-s theirs".
It is a proper part of the desired semantics, i.e. from the point of view of the surviving canonical history line, you want to preserve what it did, nullifying what the other line of history did.

Junio adds, as commented by Mike Beaton:

git merge -s ours <their-ref> effectively says 'mark commits made up to <their-ref> on their branch as commits to be permanently ignored';
and this matters because, if you subsequently merge from later states of their branch, their later changes will be brought in without the ignored changes ever being brought in.

In Python, how do I read the exif data for an image?

You can also use the ExifRead module:

import exifread
# Open image file for reading (binary mode)
f = open(path_name, 'rb')

# Return Exif tags
tags = exifread.process_file(f)

Can I add extension methods to an existing static class?

It is not possible to write an extension method, however it is possible to mimic the behaviour you are asking for.

using FooConsole = System.Console;

public static class Console
    public static void WriteBlueLine(string text)
        FooConsole.ForegroundColor = ConsoleColor.Blue;

This will allow you to call Console.WriteBlueLine(fooText) in other classes. If the other classes want access to the other static functions of Console, they will have to be explicitly referenced through their namespace.

You can always add all of the methods in to the replacement class if you want to have all of them in one place.

So you would have something like

using FooConsole = System.Console;

public static class Console
    public static void WriteBlueLine(string text)
        FooConsole.ForegroundColor = ConsoleColor.Blue;
    public static void WriteLine(string text)

This would provide the kind of behaviour you are looking for.

*Note Console will have to be added through the namespace that you put it in.

Difference between "move" and "li" in MIPS assembly language

The move instruction copies a value from one register to another. The li instruction loads a specific numeric value into that register.

For the specific case of zero, you can use either the constant zero or the zero register to get that:

move $s0, $zero
li   $s0, 0

There's no register that generates a value other than zero, though, so you'd have to use li if you wanted some other number, like:

li $s0, 12345678

How to request Administrator access inside a batch file

Based on post by toster-cx and other interesting posts on this page, I got insight on how to configure and solve my problem. I had similar issue where I wished that Disk Cleanup utility runs every week twice on Monday and Thursday during lunch hours (say 2 pm). However, this required elevated rights.

Sharing batch file which might help other beginners like me -

@echo off
echo  Welcome to scheduling 'PC Maintenance Activity'
ping localhost -n 3 >nul
echo -- Step - 1 of 3 : Please give 'Admin' rights on next screen
ping localhost -n 5 >nul
if not "%1"=="am_admin" (powershell start -verb runas '%0' am_admin & exit)
echo -- Step - 2 of 3 : In next screen, select temp areas for cleaning 
during routine scheduled activity
ping localhost -n 3 >nul
C:\Windows\System32\cleanmgr.exe /sageset:112
echo    Now scheduling maintenance activity...
SchTasks /Create /SC WEEKLY /D MON,THU /TN PC_Cleanup /TR 
"C:\Windows\System32\cleanmgr.exe "/sagerun:112 /ST 14:00


echo                         -- Thanks for your co-operation --
echo                    -- Maintenance activity is scheduled for --
echo                       -- Every Monday and Thursday at 2 pm --

ping localhost -n 10 >nul

Thanks a lot for this forum and Rems POST here [][1]

His post helped for configuring optional argument while scheduling the task.

Possible to extend types in Typescript?

May be below approach will be helpful for someone TS with reactjs

interface Event {
   name: string;
   dateCreated: string;
   type: string;

interface UserEvent<T> extends Event<T> {
    UserId: string;

jQuery AutoComplete Trigger Change Event

This post is pretty old, but for thoses who got here in 2016. None of the example here worked for me. Using keyup instead of autocompletechange did the job. Using jquery-ui 10.4

$("#CompanyList").on("keyup", function (event, ui) {

Hope this help!

Force uninstall of Visual Studio

This is an odd solution, but it worked for me.

I wanted to uninstall Visual Studio 2015 and do a clean install afterwards, but when I tried to remove it through the Control Panel, it was giving me a generic error.

I fixed it by deleting the Visual Studio 2015 folder in Program Files (x86). After that, the Control Panel uninstall worked fine.

How to add a button dynamically in Android?

for (int k = 1; k < 100; k++) {
    TableRow row = new TableRow(this);

    for (int l = 1; l < 4; l++) {
        btn = new Button(this);
        TableRow.LayoutParams tr = new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        tr.weight = 0;

        btn.setText("Button " + idb);

Firefox 'Cross-Origin Request Blocked' despite headers

Ubuntu Firefox giving CORS failed error when my request took more than 10 seconds to process.

Nothing to do with CORS. Problem is with ubuntu firefox configuration.

I have updated network.notify.changed to false which made this fix.

Mozilla Bugs Reference:

Load arrayList data into JTable

You probably need to use a TableModel (Oracle's tutorial here)

How implements your own TableModel

public class FootballClubTableModel extends AbstractTableModel {
  private List<FootballClub> clubs ;
  private String[] columns ; 

  public FootBallClubTableModel(List<FootballClub> aClubList){
    clubs = aClubList ;
    columns = new String[]{"Pos","Team","P", "W", "L", "D", "MP", "GF", "GA", "GD"};

  // Number of column of your table
  public int getColumnCount() {
    return columns.length ;

  // Number of row of your table
  public int getRowsCount() {
    return clubs.size();

  // The object to render in a cell
  public Object getValueAt(int row, int col) {
    FootballClub club = clubs.get(row);
    switch(col) {
      case 0: return club.getPosition();
      // to complete here...
      default: return null;

  // Optional, the name of your column
  public String getColumnName(int col) {
    return columns[col] ;


You maybe need to override anothers methods of TableModel, depends on what you want to do, but here is the essential methods to understand and implements :)
Use it like this

List<FootballClub> clubs = getFootballClub();
TableModel model = new FootballClubTableModel(clubs);
JTable table = new JTable(model);

Hope it help !

What are the differences between Pandas and NumPy+SciPy in Python?

pandas provides high level data manipulation tools built on top of NumPy. NumPy by itself is a fairly low-level tool, similar to MATLAB. pandas on the other hand provides rich time series functionality, data alignment, NA-friendly statistics, groupby, merge and join methods, and lots of other conveniences. It has become very popular in recent years in financial applications. I will have a chapter dedicated to financial data analysis using pandas in my upcoming book.

use std::fill to populate vector with increasing numbers

I've seen the answers with std::generate but you can also "improve" that by using static variables inside the lambda, instead of declaring a counter outside of the function or creating a generator class :

std::vector<int> vec;
std::generate(vec.begin(), vec.end(), [] {
    static int i = 0;
    return i++;

I find it a little more concise

Unix - copy contents of one directory to another

Try this:

cp Folder1/* Folder2/

Get first n characters of a string

If you want to cut being careful to don't split words you can do the following

function ellipse($str,$n_chars,$crop_str=' [...]')
    if(strlen($buff) > $n_chars)
        $cut_index=strpos($buff,' ',$n_chars);
        $buff=substr($buff,0,($cut_index===false? $n_chars: $cut_index+1)).$crop_str;
    return $buff;

if $str is shorter than $n_chars returns it untouched.

If $str is equal to $n_chars returns it as is as well.

if $str is longer than $n_chars then it looks for the next space to cut or (if no more spaces till the end) $str gets cut rudely instead at $n_chars.

NOTE: be aware that this method will remove all tags in case of HTML.

Javascript date.getYear() returns 111 in 2011?

In order to comply with boneheaded precedent, getYear() returns the number of years since 1900.

Instead, you should call getFullYear(), which returns the actual year.

Spring Data JPA findOne() change to Optional how to use this?

Optional api provides methods for getting the values. You can check isPresent() for the presence of the value and then make a call to get() or you can make a call to get() chained with orElse() and provide a default value.

The last thing you can try doing is using @Query() over a custom method.

How do I enter a multi-line comment in Perl?

I found it. Perl has multi-line comments:


use strict;

use warnings;

=for comment

Example of multiline comment.

Example of multiline comment.


print "Multi Line Comment Example \n";

How to build a Horizontal ListView with RecyclerView?

Is there a better way to implement this now with Recyclerview now?


When you use a RecyclerView, you need to specify a LayoutManager that is responsible for laying out each item in the view. The LinearLayoutManager allows you to specify an orientation, just like a normal LinearLayout would.

To create a horizontal list with RecyclerView, you might do something like this:

LinearLayoutManager layoutManager
    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

RecyclerView myList = (RecyclerView) findViewById(;

Regular expression to detect semi-colon terminated C++ for & while loops

This is a great example of using the wrong tool for the job. Regular expressions do not handle arbitrarily nested sub-matches very well. What you should do instead is use a real lexer and parser (a grammar for C++ should be easy to find) and look for unexpectedly empty loop bodies.

How to remove a directory from git repository?

To remove folder/directory only from git repository and not from the local try 3 simple commands.

Steps to remove directory

git rm -r --cached FolderName
git commit -m "Removed folder from repository"
git push origin master

Steps to ignore that folder in next commits

To ignore that folder from next commits make one file in root folder (main project directory where the git is initialized) named .gitignore and put that folder name into it. You can ignore as many files/folders as you want

.gitignore file will look like this


remove directory

How to return dictionary keys as a list in Python?

Converting to a list without using the keys method makes it more readable:


and, when looping through dictionaries, there's no need for keys():

for key in newdict:
    print key

unless you are modifying it within the loop which would require a list of keys created beforehand:

for key in list(newdict):
    del newdict[key]

On Python 2 there is a marginal performance gain using keys().

ASP.NET MVC - Getting QueryString values

Actually you can capture Query strings in MVC in two ways.....

public ActionResult CrazyMVC(string knownQuerystring)

  // This is the known query string captured by the Controller Action Method parameter above
  string myKnownQuerystring = knownQuerystring;

  // This is what I call the mysterious "unknown" query string
  // It is not known because the Controller isn't capturing it
  string myUnknownQuerystring = Request.QueryString["unknownQuerystring"];

  return Content(myKnownQuerystring + " - " + myUnknownQuerystring);


This would capture both query strings...for example:


Output: 123 - 456

Don't ask me why they designed it that way. Would make more sense if they threw out the whole Controller action system for individual query strings and just returned a captured dynamic list of all strings/encoded file objects for the URL by url-form-encoding so you can easily access them all in one call. Maybe someone here can demonstrate that if its possible?

Makes no sense to me how Controllers capture query strings, but it does mean you have more flexibility to capture query strings than they teach you out of the box. So pick your poison....both work fine.

Disable developer mode extensions pop up in Chrome

Now, we need to handle it using following -

ChromeOptions chromeOptions = new ChromeOptions();
chromeOptions.addArguments("chrome.switches", "--disable-extensions --disable-extensions-file-access-check --disable-extensions-http-throttling");

Apart from --disable-extensions, we also need to add --disable-extensions-file-access-check (and/or) --disable-extensions-http-throttling chrome switches.

Make index.html default, but allow index.php to be visited if typed in

DirectoryIndex index.html index.htm default.htm index.php index.php3 index.phtml index.php5 index.shtml mwindex.phtml

it doesn't has any means? you may be just need to add like this!

<IfModule dir_module>
    DirectoryIndex index.php index.html index.htm

enter image description here

Create comma separated strings C#?

Another approach is to use the CommaDelimitedStringCollection class from System.Configuration namespace/assembly. It behaves like a list plus it has an overriden ToString method that returns a comma-separated string.

Pros - More flexible than an array.

Cons - You can't pass a string containing a comma.

CommaDelimitedStringCollection list = new CommaDelimitedStringCollection();

list.AddRange(new string[] { "Huey", "Dewey" });

string s = list.ToString(); //Huey,Dewey,Louie

How to check if two words are anagrams

private static boolean checkAnagram(String s1, String s2) {
   if (s1 == null || s2 == null) {
       return false;
   } else if (s1.length() != s2.length()) {
       return false;
   char[] a1 = s1.toCharArray();
   char[] a2 = s2.toCharArray();
   int length = s2.length();
   int s1Count = 0;
   int s2Count = 0;
   for (int i = 0; i < length; i++) {
   return s2Count == s1Count ? true : false;

Apache could not be started - ServerRoot must be a valid directory and Unable to find the specified module

  1. Navigate to your XAMPP directory, you will find a folder called apache, open it, then copy its path, my path is "D:\Hacking Tools 2\Programs\XAMPP V2\apache"
  2. Open up apache\conf\httpd.conf with any text editor
  3. Scroll down until line 30-40
  4. You will find a code like this: ServerRoot "xampp\apache"
  5. Now, change it to be the apache directory, as I said in Step #1, my path is "D:\Hacking Tools 2\Programs\XAMPP V2\apache", so, my code will be ServerRoot "D:\Hacking Tools 2\Programs\XAMPP V2\apache"
  6. It should look somehow like this: ServerRoot "D:\XAMPP\apache"
  7. Now go back to the XAMPP main directory and run xampp_start.exe

It worked for me, if it doesn't work for you, just comment with the error value after opening the xampp_start.exe

How do I count the number of rows and columns in a file using bash?

awk 'BEGIN{FS=","}END{print "COLUMN NO: "NF " ROWS NO: "NR}' file

You can use any delimiter as field separator and can find numbers of ROWS and columns

Getting error "The package appears to be corrupt" while installing apk file

None of the answer is working for me.

As the error message is package corrupt , I will have to run

  1. adb uninstall <package name>
  2. Run app again / use adb install

Getting SyntaxError for print with keyword argument end=' '

It looks like you're just missing an opening double-quote. Try:

if Verbose:
   print("Building internam Index for %d tile(s) ..." % len(inputTiles), end=' ')

What's the use of session.flush() in Hibernate

I only know that when we call session.flush() our statements are execute in database but not committed.

Suppose we don't call flush() method on session object and if we call commit method it will internally do the work of executing statements on the database and then committing.

commit=flush+commit (in case of functionality)

Thus, I conclude that when we call method flush() on Session object, then it doesn't get commit but hits the database and executes the query and gets rollback too.

In order to commit we use commit() on Transaction object.

Font Awesome & Unicode

I found that this worked

content: "\f2d7" !important;
font-family: FontAwesome !important;

It didn't seem to work without the !important for me.

Here's a tutorial on how to change social icons with Unicodes

What are Transient and Volatile Modifiers?

volatile and transient keywords

1) transient keyword is used along with instance variables to exclude them from serialization process. If a field is transient its value will not be persisted.

On the other hand, volatile keyword is used to mark a Java variable as "being stored in main memory".

Every read of a volatile variable will be read from the computer's main memory, and not from the CPU cache, and that every write to a volatile variable will be written to main memory, and not just to the CPU cache.

2) transient keyword cannot be used along with static keyword but volatile can be used along with static.

3) transient variables are initialized with default value during de-serialization and there assignment or restoration of value has to be handled by application code.

For more information, see my blog:

Is there any simple way to convert .xls file to .csv file? (Excel)

Here's a C# method to do this. Remember to add your own error handling - this mostly assumes that things work for the sake of brevity. It's 4.0+ framework only, but that's mostly because of the optional worksheetNumber parameter. You can overload the method if you need to support earlier versions.

static void ConvertExcelToCsv(string excelFilePath, string csvOutputFile, int worksheetNumber = 1) {
   if (!File.Exists(excelFilePath)) throw new FileNotFoundException(excelFilePath);
   if (File.Exists(csvOutputFile)) throw new ArgumentException("File exists: " + csvOutputFile);

   // connection string
   var cnnStr = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=\"Excel 8.0;IMEX=1;HDR=NO\"", excelFilePath);
   var cnn = new OleDbConnection(cnnStr);

   // get schema, then data
   var dt = new DataTable();
   try {
      var schemaTable = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
      if (schemaTable.Rows.Count < worksheetNumber) throw new ArgumentException("The worksheet number provided cannot be found in the spreadsheet");
      string worksheet = schemaTable.Rows[worksheetNumber - 1]["table_name"].ToString().Replace("'", "");
      string sql = String.Format("select * from [{0}]", worksheet);
      var da = new OleDbDataAdapter(sql, cnn);
   catch (Exception e) {
      // ???
      throw e;
   finally {
      // free resources

   // write out CSV data
   using (var wtr = new StreamWriter(csvOutputFile)) {
      foreach (DataRow row in dt.Rows) {
         bool firstLine = true;
         foreach (DataColumn col in dt.Columns) {
            if (!firstLine) { wtr.Write(","); } else { firstLine = false; }
            var data = row[col.ColumnName].ToString().Replace("\"", "\"\"");
            wtr.Write(String.Format("\"{0}\"", data));

Use PHP composer to clone git repo

In my case, I use Symfony2.3.x and the minimum-stability parameter is by default "stable" (which is good). I wanted to import a repo not in packagist but had the same issue "Your requirements could not be resolved to an installable set of packages.". It appeared that the composer.json in the repo I tried to import use a minimum-stability "dev".

So to resolve this issue, don't forget to verify the minimum-stability. I solved it by requiring a dev-master version instead of master as stated in this post.

How to remove duplicate white spaces in string using Java?

You can also try using String Tokeniser, for any space, tab, newline, and all. A simple way is,

String s = "Your Text Here";        
StringTokenizer st = new StringTokenizer( s, " " );

How to insert values in two dimensional array programmatically?

String[][] shades = new String[intSize][intSize];
 // print array in rectangular form
 for (int r=0; r<shades.length; r++) {
     for (int c=0; c<shades[r].length; c++) {
         shades[r][c]="hello";//your value

How would you count occurrences of a string (actually a char) within a string?

I've made some research and found that Richard Watson's solution is fastest in most cases. That's the table with results of every solution in the post (except those use Regex because it throws exceptions while parsing string like "test{test")

    Name      | Short/char |  Long/char | Short/short| Long/short |  Long/long |
    Inspite   |         134|        1853|          95|        1146|         671|
    LukeH_1   |         346|        4490|         N/A|         N/A|         N/A|
    LukeH_2   |         152|        1569|         197|        2425|        2171|
Bobwienholt   |         230|        3269|         N/A|         N/A|         N/A|
Richard Watson|          33|         298|         146|         737|         543|
StefanosKargas|         N/A|         N/A|         681|       11884|       12486|

You can see that in case of finding number of occurences of short substrings (1-5 characters) in short string(10-50 characters) the original algorithm is preferred.

Also, for multicharacter substring you should use the following code (based on Richard Watson's solution)

int count = 0, n = 0;

if(substring != "")
    while ((n = source.IndexOf(substring, n, StringComparison.InvariantCulture)) != -1)
        n += substring.Length;

C++ equivalent of StringBuffer/StringBuilder?

std::string's += doesn't work with const char* (what stuff like "string to add" appear to be), so definitely using stringstream is the closest to what is required - you just use << instead of +

How do you import an Eclipse project into Android Studio now?

Android Studio has been improved since this question was posted, and the latest versions of Android Studio (as of this writing, we are at 2.1.1) have fairly good Eclipse importing capabilities, so importing Eclipse projects directly into Android Studio is now the best approach for migrating projects from Eclipse into Android Studio.

I will describe how to do this below, including a few of the pitfalls that one might encounter. I will deal in particular with importing an Eclipse workspace that contains multiple apps sharing one or more project libraries (the approaches posted thus far seem limited to importing just one Eclipse app project and its project libraries). While I don't deal with every possible issue, I do go into a lot of detail regarding some of them, which I hope will be helpful to those going through this process for the first time themselves.

I recently imported the projects from an Eclipse workspace. This workspace included four library projects that were shared between up to nine projects each.

Some background:

An Eclipse workspace contains multiple projects, which may be library projects or apps.

An Android Studio project is analogous to an Eclipse workspace, in that it can contain both library projects and apps. However, a library project or an app is represented by a "module" in Android Studio, whereas it is represented by a "project" in Eclipse.

So, to summarize: Eclipse workspaces will end up as Android Studio projects, and Eclipse projects inside a workspace will end up as Android Studio modules inside a project.

You should start the import process by creating an Android Studio project (File / New / New Project). You might give this project the same (or similar) name as you gave your Eclipse workspace. This project will eventually hold all of your modules, one each for each Eclipse project (including project libraries) that you will import.

The import process does not change your original Eclipse files, so long as you place the imported files in a different folder hierarchy, so you should choose a folder for this project that is not in your original Eclipse hierarchy. For example, if your Eclipse projects are all in a folder called Android, you might create a sibling folder called AStudio.

Your Android Studio project can then be created as a sub-folder of this new folder. The New Project wizard will prompt you to enter this top-level project folder, into which it will create your project.

Android Studio's new project wizard will then ask you to configure a single module at the time you create the project. This can be a little confusing at first, because they never actually tell you that you are creating a module, but you are; you are creating a project with a single module in it. Apparently, every project is required to have at least one module, so, since you are relying on Eclipse to provide your modules, your initial module will be a placeholder to vacuously satisfy that formal requirement.

Thus, you probably will want to create an initial module for your project that does as little as possible. Therefore, select Phone and Tablet as the type of your module, accept the default minimum SDK (API level 8), and select Add No Activity for your module.

Next, select one of the Eclipse app projects in your workspace that requires the largest number of libraries as your first project to import. The advantage of doing this is that when you import that project, all the library projects that it uses (directly, or indirectly, if some of your library projects themselves require other library projects) will get imported along with it as part of the importing process.

Each of these imported projects will get its own module within your Android Studio project. All of these modules will be siblings of one another (both in your project hierarchy, and in the folder hierarchy where their files are placed), just as if you had imported the modules separately. However, the dependencies between the modules will be created for you (in your app's build.gradle files) as part of the importing process.

Note that after you finish importing, testing and debugging this "most dependent" Eclipse project and its supporting library projects, you will go on to import a second Eclipse app project (if you have a second one in your workspace) and its library project modules (with those imported earlier getting found by the import wizard as existing modules and re-used for this new module, rather than being duplicated).

So, you should never have to import even a single library project from Eclipse directly; they will all be brought in indirectly, based on their dependencies upon app projects that you import. This is assuming that all of your library projects in the workspace are created to serve the needs of one or more app projects in that same workspace.

To perform the import of this first app project, back in Android Studio, while you are in the project that you just created, select File / New / New Module. You might think that you should be using File / New / Import Module, but no, you should not, because if you do that, Android Studio will create a new project to hold your imported module, and it will import your module to that project. You actually could create your first module that way, but then the second through Nth modules would still require that you use this other method (for importing a module into an existing project), and so I think that just starting with an "empty" project (or rather, one with its own vacuous, do-nothing placeholder module), and then importing each of your Eclipse projects as a new module into that project (i.e., the approach we are taking here), may be less confusing.

So, you are going to take your practically-empty new project, and perform a File / New / New Module in it. The wizard that this invokes will give you a choice of what kind of module you want to create. You must select "Import Eclipse ADT Project." That is what accesses the wizard that knows how to convert an Eclipse project into an Android Studio module (along with the library modules on which it depends) within your current Android Studio project.

When prompted for a source folder, you should enter the folder for your Eclipse project (this is the folder that contains that project's AndroidManifest.xml file).

The import wizard will then display the module name that it intends to create (similar to your original Eclipse project's name, but with a lower-case first letter because that is a convention that distinguishes module names from project names (which start with an upper-case letter). It usually works pretty well to accept this default.

Below the module name is a section titled "Additional required modules." This will list every library required by the module you are importing (or by any of its libraries, etc.). Since this is the first module you are importing, none of these will already be in your project, so each of them will have its Import box checked by default. You should leave these checked because you need these modules. (Note that when you import later Eclipse app projects, if a library that they need has already been imported, those libraries will still appear here, but there will be a note that "Project already contains module with this name," and the Import box will be un-checked by default. In that case, you should leave the box unchecked, so that the importer will hook up your newly-imported module(s) to the libraries that have already been imported. It may be that accepting the default names that Android Studio creates for your modules will be important for allowing the IDE to find and re-use these library modules.

Next, the importer will offer to replace any jars and library sources with Gradle dependencies, and to create camelCase module names for any dependent modules, checking all those options by default. You should generally leave these options checked and continue. Read the warning, though, about possible problems. Remember that you can always delete an imported module or modules (via the Project Structure dialog) and start the import process over again.

The next display that I got (YMMV) claims that the Android Support Repository is not installed in my SDK installation. It provides a button to open the Android SDK Manager for purposes of installing it. However, that button did not work for me. I manually opened the SDK manager as a separate app, and found that the Android Support Repository was already installed. There was an update, however. I installed that, and tapped the Refresh button in the import dialog, but that did nothing. So, I proceeded, and the perceived lack of this Repository did not seem to hurt the importing process (although I did get messages regarding it being missing from time to time later on, while working with the imported code, which I was able to appease by clicking a supplied link that corrected the problem - at least temporarily). Eventually this problem went away when I installed an update to the repository, so you may not experience it at all.

At this point, you will click Finish, and after a bit it should create your modules and build them. If all goes well, you should get a BUILD SUCCESSFUL message in your Gradle Console.

One quirk is that if the build fails, you may not see your imported modules in the Project hierarchy. It seems that you need to get to the first valid build before the new modules will appear there (my experience, anyway). You may still be able to see the new modules in the File / Project Structure dialog (e.g., if you want to delete them and start your import over).

Remember that since you are not changing your original Eclipse projects, you can always delete the modules that you have just imported (if importing goes badly), and start all over again. You can even make changes to the Eclipse side after deleting your Android Studio modules, if that will make importing go better the second time (so long as you preserve your fallback ability to build your existing source under Eclipse). As you'll see when we discuss version control below, it may be necessary for you to retain your ability to build under Eclipse, because the project structure is changed under Android Studio, so if you need to go back to a commit that precedes your move to Android Studio (e.g., to make a bug fix), you will want to have the ability to build that earlier commit in Eclipse.

To delete a module, you must select File / Project Structure, then select the module from the left side of the dialog, and then hit the delete key. For some reason, I was not able to delete a module directly in the Project hierarchy; it had to be done using this Project Structure dialog.

The import wizard generates an import-summary.txt file containing a detailed list of any issues it may have encountered, along with actions taken to resolve them. You should read it carefully, as it may provide clues as to what is happening if you have trouble building or running the imported code. It will also help you to find things that the importer moves around to accommodate the different structure of Android Studio projects.

If all does not go well, then have at look at these possible problems that you may encounter, along with solutions for those problems:

Generally speaking, there are two main kinds of problems that I encountered:

  1. Proguard problems
  2. Manifest problems

When Proguard is messed up, the (obfuscated) names of methods in your libraries may not match the names being used to invoke them from your app, and you will get compiler errors like "error: cannot find symbol class ..."

In Eclipse, Proguard stuff is pretty much ignored for library projects, with the Proguard stuff for any app project that you are building determining the obfuscation, etc. for not just itself, but for processing all of the libraries on which it depends. And that is generally what you want.

In Android Studio, however, you need to make some changes to attain this same effect. Basically, in the build.gradle files for each of your library project modules, you will want something like this:

buildTypes {
    release {
        minifyEnabled false
        consumerProguardFiles 'proguard.cfg'

Where proguard.cfg is your library module's own proguard configuration file.

The term "consumer" in "consumerProguardFiles" apparently refers to the app module that is using this library module. So the proguard commands from that app are used in preference to those of the library module itself, and apparently this results in obfuscations that are coordinated and compatible, so that all calls from the app module to its library modules are made with matching symbols.

These "consumerProguardFiles" entries are not created automatically during the import process (at least that was my own experience) so you will want to make sure to edit that into your library modules' build.gradle files if they are not created for you during importing.

If you wanted to distribute your library projects separately, with obfuscation, then you would need an individual proguard file for them; I have not done this myself, and so that is beyond the scope of this answer.

In the app module, you will want something like this:

buildTypes {
    release {
        minifyEnabled true
        proguardFiles 'proguard.cfg'

(BTW, as of this writing, while my apps are running just fine, I have not yet directly confirmed that things are actually getting obfuscated using this approach, so do check this yourself - e.g., by using a decompiler like apktool. I will be checking this later on, and will edit this answer when I get that info).

The second kind of problem is due to the fact that Eclipse pretty much ignores the manifest files for library projects when compiling an app project that uses those library projects, while in Android Studio, there is an interleaving of the two that apparently does not consistently prioritize the app's manifest over those of its libraries.

I encountered this because I had a library manifest that listed (just for documentation purposes) an abstract Activity class as the main activity. There was a class derived from this abstract class in my app that was declared in the manifest of each app that used the library.

In Eclipse, this never caused any problems, because the library manifests were ignored. But in Android Studio, I ended up with that abstract class as my activity class for the app, which caused a run-time error when the code made an attempt to instantiate that abstract class.

You have two choices in this case:

  1. Use tools syntax to override specific library manifest stuff in your app manifest - for example:
<manifest xmlns:android=""


  1. Strip out practically everything from your library modules' manifests, and rely upon the app module's manifest to provide every value. Note that you do need to have a manifest for each library module, but not much more is required than the header and a bare manifest element with just a package attribute in it.

I tried both and ended up with approach 2., above, as the simpler method. However, if you wanted to distribute your library modules separately, you would need to create a more meaningful manifest file that reflects each library module's own individual requirements.

There is probably a more "correct" way to do this which puts requirements (e.g., permissions) for each library in the library manifest itself, and allows the automatic interleaving process to combine these with those declared for the app. However, given that Eclipse ignores the manifests for libraries, it seems safer at least initially to rely entirely on the app manifests and just strip the library manifests down to the bare bones.

Be aware that some of the project properties, and also the manifest attributes, from your Eclipse project will have been used to construct portions of your build.gradle files. Specifically, your compileSdkVersion in build.gradle is set to the project build version from the Eclipse project properties, applicationId is the package name from your app's manifest, and minSdkVersion and targetSdkVersion are also copied from the app's manifest file. The dependencies section of build.gradle comes from the library project dependencies in your project's properties.

Note that this may make some of your AndroidManifest.xml values redundant and quite possibly residual (i.e., unused). This could create confusion. My understanding is that the build.gradle values are the ones that actually have an effect, and that the manifest values like targetSdkVersion are not used any more for purposes of building. However, they may still be used by app stores such as Google Play; I don't know for certain one way or the other, so at this point I am just maintaining them in tandem.

Besides the above two kinds of issue, there are more routine things like importing a project that has a project build level of 22 when you have only installed SDK level 23 in Android Studio. In that situation, it is probably better to edit your app module's build.gradle file to move compileSdkVersion from 22 (the imported value) to 23, than it would be to install the SDK for level 22, but either approach should work.

Throughout this entire process, when something does not build properly and you make a change to try to address it, you might want to try Build / Rebuild Project and/or Tools / Android / Sync Project with Gradle Files, and/or File / Invalidate Caches/Restart, to make sure that your changes have been fully incorporated. I don't know exactly when these are truly necessary, because I don't know how much is done incrementally when you haven't yet had a successful build, but I performed them all fairly regularly as a kind of superstitious ritual, and I'm fairly certain that it helped. For example, when I got a Resources$NotFound runtime error that appeared to be from an inability to find the launch icon resource, I tried all three, and the problem was fixed.

When you have performed the above for your first Eclipse project and have attained a successful build, then with luck, you can select your app module from the dropdown at the top of the Android Studio display to the left of the play button, then click the play button itself, then select a device or Android Virtual Device, and the app should be loaded for running.

Likewise, you should be able to create a signed copy of your app using the Build / Generate Signed APK feature. Note that some import-related errors may appear when running your signed copy that do not appear when using the play button, so you need to confirm that both are working before deciding that your import is complete.

Following this, you will probably want to turn on version control. I am using git myself, but there are a number of other options available.

Version control is mostly beyond the scope of this answer, but there are a few things that are affected by the importing process. First, in Eclipse you might have your various projects in various folders stuck all over the place, but when you import into Android Studio, all modules will be created as direct child folders of your main project folder. So if you had a separate git folder for each project in Eclipse, or for related groups of projects organized under a parent folder for each group (as I did), that is not going to translate very well to Android Studio.

My knowledge of this is limited as I have not worked with version control yet in Android Studio, so maybe there is a way around this, but it appears that all version control in Android Studio is unified at the project level, and so all of your modules will be under a single git archive.

This means that you may need to abandon your old git archive and start fresh with a new archive for your imported source code. And that means that you will want to keep your old git archive around, so that it can be used with Eclipse to perform any needed bug fixes, etc., at least for a while. And you also will want it to preserve a history of your project.

If you are fortunate enough to have had all of your projects organized under a single Eclipse workspace, and if you were using a single git archive for those projects, then it is possible that you might just copy your old git archive from in and under your Eclipse workspace folder to in and under your Android Studio project folder. Then, you could edit any still-relevant .gitignore items from you Eclipse project into the auto-generated .gitignore file for your Android Studio project, and let git figure out what has been changed during the importing process (and some things will have been moved around - for example, the manifest file is no longer at the top level of your module). Others have reported that git is pretty good at figuring out what has changed; I have not tried this myself.

But even if you did this, going back to a commit that precedes your move from Eclipse to Android Studio would be going back to a set of files that would only make sense from inside Eclipse. So it sounds, well, "difficult" to work with. Especially since Eclipse will still be pointing to its original set of project folders.

I personally had multiple git archives for my various sets of related projects, and so I decided to just make a clean break and start git over again in Android Studio. If you had to do this, it could affect your planning, because you would want to be at a very stable point in your code development before making the move in that case, since you will lose some accessibility to that older code within your version control system (e.g., ability to merge with post-import code) once you have made the move to Android Studio.

The part of this answer that pertains to git is partly speculative, since I have not actually worked with version control yet on my imported project files, but I wanted to include it to give some idea of the challenges, and I plan to update my answer after I have worked more with version control inside Android Studio.

How to set image in imageview in android?

Instead of setting drawable resource through code in your activity class you can also set in XML layout:

Code is as follows:

        android:src="@drawable/apple" />

How to select a value in dropdown javascript?

easiest way is to just use this

document.getElementById("mySelect").value = "banana";

myselect is name of your dropdown banana is just one of items in your dropdown list

How do you uninstall all dependencies listed in package.json (NPM)?

Another SIMPLE option is to delete the node_modules and package-lock.json

rm -rf node_modules
rm -rf package-lock.json

After this you can try reinstalling the npm packages

How to display with n decimal places in Matlab

i use like tim say sprintf('%0.6f', x), it's a string then i change it to number by using command str2double(x).

How to run an application as "run as administrator" from the command prompt?

Try this:

runas.exe /savecred /user:administrator "%sysdrive%\testScripts\testscript1.ps1" 

It saves the password the first time and never asks again. Maybe when you change the administrator password you will be prompted again.

What does operator "dot" (.) mean?

There is a whole page in the MATLAB documentation dedicated to this topic: Array vs. Matrix Operations. The gist of it is below:

MATLAB® has two different types of arithmetic operations: array operations and matrix operations. You can use these arithmetic operations to perform numeric computations, for example, adding two numbers, raising the elements of an array to a given power, or multiplying two matrices.

Matrix operations follow the rules of linear algebra. By contrast, array operations execute element by element operations and support multidimensional arrays. The period character (.) distinguishes the array operations from the matrix operations. However, since the matrix and array operations are the same for addition and subtraction, the character pairs .+ and .- are unnecessary.

How do you get the length of a string?

You don't need to use jquery.

var myString = 'abc';
var n = myString.length;

n will be 3.

Updating GUI (WPF) using a different thread

You may use a delegate to solve this issue. Here is an example that is showing how to update a textBox using diffrent thread

public delegate void UpdateTextCallback(string message);

private void TestThread()
    for (int i = 0; i <= 1000000000; i++)
            new UpdateTextCallback(this.UpdateText),
            new object[] { i.ToString() }
private void UpdateText(string message)
    richTextBox1.AppendText(message + "\n");

private void button1_Click(object sender, RoutedEventArgs e)
   Thread test = new Thread(new ThreadStart(TestThread));

TestThread method is used by thread named test to update textBox

Installing Node.js (and npm) on Windows 10

New installers (.msi downloaded from have "Add to PATH" option. By default it is selected. Make sure that you leave it checked.

Add to PATH

How do I call a dynamically-named method in Javascript?

Hi try this,

 var callback_function = new Function(functionName);

it will handle the parameters itself.

Run reg command in cmd (bat file)?

If memory serves correct, the reg add command will NOT create the entire directory path if it does not exist. Meaning that if any of the parent registry keys do not exist then they must be created manually one by one. It is really annoying, I know! Example:

@echo off
reg add "HKCU\Software\Policies"
reg add "HKCU\Software\Policies\Microsoft"
reg add "HKCU\Software\Policies\Microsoft\Internet Explorer"
reg add "HKCU\Software\Policies\Microsoft\Internet Explorer\Control Panel"
reg add "HKCU\Software\Policies\Microsoft\Internet Explorer\Control Panel" /v HomePage /t REG_DWORD /d 1 /f

Equivalent of *Nix 'which' command in PowerShell?

If you want a comamnd that both accepts input from pipeline or as paramater, you should try this:

function which($name) {
    if ($name) { $input = $name }
    Get-Command $input | Select-Object -ExpandProperty Path

copy-paste the command to your profile (notepad $profile).


? echo clang.exe | which
C:\Program Files\LLVM\bin\clang.exe

? which clang.exe
C:\Program Files\LLVM\bin\clang.exe

Set selected item of spinner programmatically

In my case, this code saved my day:

public static void selectSpinnerItemByValue(Spinner spnr, long value) {
    SpinnerAdapter adapter = spnr.getAdapter();
    for (int position = 0; position < adapter.getCount(); position++) {
        if(adapter.getItemId(position) == value) {

How to download Visual Studio 2017 Community Edition for offline installation?

No, there should be an .exe file (vs_Community_xxxxx.exe) directly in you f:\vs2017c directory !

Just start from the this directory, not from a longer path. the packages downloaded are partly having very long path names, it fails if you start from a longer path.

How to draw text using only OpenGL methods?

I think that the best solution for drawing text in OpenGL is texture fonts, I work with them for a long time. They are flexible, fast and nice looking (with some rear exceptions). I use special program for converting font files (.ttf for example) to texture, which is saved to file of some internal "font" format (I've developed format and program based on though my version went rather far from the original supporting Unicode and so on). When starting the main app, fonts are loaded from this "internal" format. Look link above for more information.

With such approach the main app doesn't use any special libraries like FreeType, which is undesirable for me also. Text is being drawn using standard OpenGL functions.

Delete from a table based on date

or an ORACLE version:

  from table_name
 where trunc( > to_date('01/01/2009','mm/dd/yyyy') 

How to convert datatype:object to float64 in python?

convert_objects is deprecated.

For pandas >= 0.17.0, use pd.to_numeric

df["2nd"] = pd.to_numeric(df["2nd"])

How can I get client information such as OS and browser

Here's my code that works, as of today, with some of the latest browsers.

Naturally, it will break as User-Agent's evolve, but it's simple, and easy to fix.

    String userAgent = "Unknown";
    String osType = "Unknown";
    String osVersion = "Unknown";
    String browserType = "Unknown";
    String browserVersion = "Unknown";
    String deviceType = "Unknown";

    try {
        userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36 OPR/60.0.3255.165";
        //userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0";
        //userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36";
        //userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134";
        //userAgent = "Mozilla/5.0 (iPhone; CPU iPhone OS 12_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.1.1 Mobile/15E148 Safari/604.1";
        boolean exceptionTest = false;
        if(exceptionTest) throw new Exception("EXCEPTION TEST");

        if (userAgent.indexOf("Windows NT") >= 0) {
            osType = "Windows";
            osVersion = userAgent.substring(userAgent.indexOf("Windows NT ")+11, userAgent.indexOf(";"));

        } else if (userAgent.indexOf("Mac OS") >= 0) {
            osType = "Mac";
            osVersion = userAgent.substring(userAgent.indexOf("Mac OS ")+7, userAgent.indexOf(")"));

            if(userAgent.indexOf("iPhone") >= 0) {
                deviceType = "iPhone";
            } else if(userAgent.indexOf("iPad") >= 0) {
                deviceType = "iPad";

        } else if (userAgent.indexOf("X11") >= 0) {
            osType = "Unix";
            osVersion = "Unknown";

        } else if (userAgent.indexOf("android") >= 0) {
            osType = "Android";
            osVersion = "Unknown";
        logger.trace("end of os section");

        if (userAgent.contains("Edge/")) {
            browserType = "Edge";
            browserVersion = userAgent.substring(userAgent.indexOf("Edge")).split("/")[1];

        } else if (userAgent.contains("Safari/") && userAgent.contains("Version/")) {
            browserType = "Safari";
            browserVersion = userAgent.substring(userAgent.indexOf("Version/")+8).split(" ")[0];

        } else if (userAgent.contains("OPR/") || userAgent.contains("Opera/")) {
            browserType = "Opera";
            browserVersion = userAgent.substring(userAgent.indexOf("OPR")).split("/")[1];

        } else if (userAgent.contains("Chrome/")) {
            browserType = "Chrome"; 
            browserVersion = userAgent.substring(userAgent.indexOf("Chrome")).split("/")[1];
            browserVersion = browserVersion.split(" ")[0];

        } else if (userAgent.contains("Firefox/")) {
            browserType = "Firefox"; 
            browserVersion = userAgent.substring(userAgent.indexOf("Firefox")).split("/")[1];
        logger.trace("end of browser section");

    } catch (Exception ex) {
        logger.error("ERROR: " +ex);            

              "\n userAgent: " + userAgent
            + "\n osType: " + osType
            + "\n osVersion: " + osVersion
            + "\n browserType: " + browserType
            + "\n browserVersion: " + browserVersion
            + "\n deviceType: " + deviceType

Logger Output:

 userAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36 OPR/60.0.3255.165
 osType: Windows
 osVersion: 10.0
 browserType: Opera
 browserVersion: 60.0.3255.165
 deviceType: Unknown

React Native: Possible unhandled promise rejection

According to this post, you should enable it in XCode.

  1. Click on your project in the Project Navigator
  2. Open the Info tab
  3. Click on the down arrow left to the "App Transport Security Settings"
  4. Right click on "App Transport Security Settings" and select Add Row
  5. For created row set the key “Allow Arbitrary Loads“, type to boolean and value to YES.

enter image description here

How to know Hive and Hadoop versions from command prompt?

Use the below command to get hive version

hive --service version

mailto link with HTML body

Thunderbird supports html-body: mailto:[email protected]?subject=Me&html-body=<b>ME</b>

Query to get only numbers from a string

Firstly find out the number's starting length then reverse the string to find out the first position again(which will give you end position of number from the end). Now if you deduct 1 from both number and deduct it from string whole length you'll get only number length. Now get the number using SUBSTRING

declare @fieldName nvarchar(100)='AAAA1221.121BBBB'

declare @lenSt int=(select PATINDEX('%[0-9]%', @fieldName)-1)
declare @lenEnd int=(select PATINDEX('%[0-9]%', REVERSE(@fieldName))-1)

select SUBSTRING(@fieldName, PATINDEX('%[0-9]%', @fieldName), (LEN(@fieldName) - @lenSt -@lenEnd))


This is a late answer. Starting from SQLIte 3.24.0, released on June 4, 2018, there is finally a support for UPSERT clause following PostgreSQL syntax.

INSERT INTO players (user_name, age)
  VALUES('steven', 32) 
  ON CONFLICT(user_name) 
  DO UPDATE SET age=excluded.age;

Note: For those having to use a version of SQLite earlier than 3.24.0, please reference this answer below (posted by me, @MarqueIV).

However if you do have the option to upgrade, you are strongly encouraged to do so as unlike my solution, the one posted here achieves the desired behavior in a single statement. Plus you get all the other features, improvements and bug fixes that usually come with a more recent release.

Maximum Length of Command Line String

In Windows 10, it's still 8191 least on my machine.

It just cuts off any text after 8191 characters. Well, actually, I got 8196 characters, and after 8196, then it just won't let me type any more.

Here's a script that will test how long of a statement you can use. Well, assuming you have gawk/awk installed.

echo rem this is a test of how long of a line that a .cmd script can generate >testbat.bat
gawk 'BEGIN {printf "echo -----";for (i=10;i^<=100000;i +=10) printf "%%06d----",i;print;print "pause";}' >>testbat.bat

Responsive css styles on mobile devices ONLY

Yes, this can be done via javascript feature detection ( or browser detection , e.g. Modernizr ) . Then, use yepnope.js to load required resources ( JS and/or CSS )

How do I make curl ignore the proxy?

In case of windows: use curl --proxy "" ...

sql query to return differences between two tables

Simple variation on @erikkallen answer that shows which table the row is present in:

(   SELECT 'table1' as source, * FROM table1
    SELECT * FROM table2)  
(   SELECT 'table2' as source, * FROM table2
    SELECT * FROM table1) 

If you get an error

All queries combined using a UNION, INTERSECT or EXCEPT operator must have an equal number of expressions in their target lists.

then it may help to add

(   SELECT 'table1' as source, * FROM table1
    SELECT 'table1' as source, * FROM table2)  
(   SELECT 'table2' as source, * FROM table2
    SELECT 'table2' as source, * FROM table1) 

Error: JavaFX runtime components are missing, and are required to run this application with JDK 11

This worked for me:

File >> Project Structure >> Modules >> Dependency >> + (on left-side of window)

clicking the "+" sign will let you designate the directory where you have unpacked JavaFX's "lib" folder.

Scope is Compile (which is the default.) You can then edit this to call it JavaFX by double-clicking on the line.

then in:

Run >> Edit Configurations

Add this line to VM Options:

--module-path /path/to/JavaFX/lib --add-modules=javafx.controls

(oh and don't forget to set the SDK)

How to group by month from Date field using sql

I would use this:

SELECT  Closing_Date = DATEADD(MONTH, DATEDIFF(MONTH, 0, Closing_Date), 0), 
        COUNT(Status) TotalCount 
FROM    MyTable
WHERE   Closing_Date >= '2012-02-01' 
AND     Closing_Date <= '2012-12-31'
AND     Defect_Status1 IS NOT NULL
GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, Closing_Date), 0), Category;

This will group by the first of every month, so

`DATEADD(MONTH, DATEDIFF(MONTH, 0, '20130128'), 0)` 

will give '20130101'. I generally prefer this method as it keeps dates as dates.

Alternatively you could use something like this:

SELECT  Closing_Year = DATEPART(YEAR, Closing_Date),
        Closing_Month = DATEPART(MONTH, Closing_Date),
        COUNT(Status) TotalCount 
FROM    MyTable
WHERE   Closing_Date >= '2012-02-01' 
AND     Closing_Date <= '2012-12-31'
AND     Defect_Status1 IS NOT NULL
GROUP BY DATEPART(YEAR, Closing_Date), DATEPART(MONTH, Closing_Date), Category;

It really depends what your desired output is. (Closing Year is not necessary in your example, but if the date range crosses a year boundary it may be).

Turning off eslint rule for a specific line

To disable next line:

// eslint-disable-next-line no-use-before-define
var thing = new Thing();

Or use the single line syntax:

var thing = new Thing(); // eslint-disable-line no-use-before-define

See the eslint docs

Trying to Validate URL Using JavaScript

Here's a regular expression which might fit the bill (it's very long):


There are some caveats to its usage, namely it does not validate URIs which contain additional information after the user name (e.g. "username:password"). Also, only IPv6 addresses can be contained within the IP literal syntax and the "IPvFuture" syntax is currently ignored and will not validate against this regular expression. Port numbers are also constrained to be between 0 and 65,535. Also, only the file scheme can use triple slashes (e.g. "file:///etc/sysconfig") and can ignore both the query and fragment parts of a URI. Finally, it is geared towards regular URIs and not IRIs, hence the extensive focus on the ASCII character set.

This regular expression could be expanded upon, but it's already complex and long enough as it is. I also cannot guarantee it's going to be "100% accurate" or "bug free", but it should correctly validate URIs for all schemes.

You will need to do additional verification for any scheme-specific requirements or do URI normalization as this regular expression will validate a very broad range of URIs.

Property 'map' does not exist on type 'Observable<Response>'

In rxjs 6 map operator usage has been changed now you need to Use it like this.

import { map } from 'rxjs/operators';
  .pipe(map(data => data * 2))

For reference

T-SQL loop over query results

My prefer solution is Microsoft KB 111401

The link refers to 3 examples:

This article describes various methods that you can use to simulate a cursor-like FETCH-NEXT logic in a stored procedure, trigger, or Transact-SQL batch.

/*********** example 1 ***********/ 

declare @au_id char( 11 )

set rowcount 0
select * into #mytemp from authors

set rowcount 1

select @au_id = au_id from #mytemp

while @@rowcount <> 0
    set rowcount 0
    select * from #mytemp where au_id = @au_id
    delete #mytemp where au_id = @au_id

    set rowcount 1
    select @au_id = au_id from #mytemp
set rowcount 0

/********** example 2 **********/ 

declare @au_id char( 11 )

select @au_id = min( au_id ) from authors

while @au_id is not null
    select * from authors where au_id = @au_id
    select @au_id = min( au_id ) from authors where au_id > @au_id

/********** example 3 **********/ 

set rowcount 0
select NULL mykey, * into #mytemp from authors

set rowcount 1
update #mytemp set mykey = 1

while @@rowcount > 0
    set rowcount 0
    select * from #mytemp where mykey = 1
    delete #mytemp where mykey = 1
    set rowcount 1
    update #mytemp set mykey = 1
set rowcount 0

Connecting to SQL Server with Visual Studio Express Editions

My guess is that with VWD your solutions are more likely to be deployed to third party servers, many of which do not allow for a dynamically attached SQL Server database file. Thus the allowing of the other connection type.

This difference in IDE behavior is one of the key reasons for upgrading to a full version.

Excel VBA - How to Redim a 2D array?

Here ya go.

Public Function ReDimPreserve(ByRef Arr, ByVal idx1 As Integer, ByVal idx2 As Integer)

    Dim newArr()
    Dim x As Integer
    Dim y As Integer

    ReDim newArr(idx1, idx2)

    For x = 0 To UBound(Arr, 1)
        For y = 0 To UBound(Arr, 2)
            newArr(x, y) = Arr(x, y)

    Arr = newArr

End Function

Error: "dictionary update sequence element #0 has length 1; 2 is required" on Django 1.4

Error in your question is raised when you try something like following:

>>> a_dictionary = {}
>>> a_dictionary.update([[1]])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: dictionary update sequence element #0 has length 1; 2 is required

It's hard to tell where is the cause in your code unless you show your code, full traceback.

How do I search an SQL Server database for a string?

If I want to find where anything I want to search is, I use this:

DECLARE @search_string    varchar(200)
    SET @search_string = '%myString%'

  AS Object_Name,
      FROM sys.sql_modules m
           INNER JOIN
           sys.objects o
             ON m.object_id = o.object_id
     WHERE m.definition Like @search_string;

How to combine results of two queries into a single dataset

This is what you can do. Assuming that your ProductName column have common values.

FROM Table1
ON Table1.ProductName= Table2.ProductName

Notice: Array to string conversion in

Store the Value of $_SESSION['username'] into a variable such as $username


$get = @mysql_query("SELECT money FROM players WHERE username = 

it should work!

jQuery datepicker years shown

au, nz, ie, etc. are the country codes for the countries whose national days are being displayed (Australia, New Zealand, Ireland, ...). As seen in the code, these values are combined with '_day' and passed back to be applied to that day as a CSS style. The corresponding styles are of the form show below, which moves the text for that day out of the way and replaces it with an image of the country's flag.

.au_day {
  text-indent: -9999px;
  background: #eee url(au.gif) no-repeat center;

The 'false' value that is passed back with the new style indicates that these days may not be selected.

Why should the static field be accessed in a static way?

Because when you access a static field, you should do so on the class (or in this case the enum). As in


Not on an instance as in


Edit To address the question of why: In Java, when you declare something as static, you are saying that it is a member of the class, not the object (hence why there is only one). Therefore it doesn't make sense to access it on the object, because that particular data member is associated with the class.

How to automatically select all text on focus in WPF TextBox?

I realize this is very old, but here is my solution which is based on the expressions/microsoft interactivity and interactions name spaces.

First, I followed the instructions at this link to place interactivity triggers into a style.

Then it comes down to this

<Style x:Key="baseTextBox" TargetType="TextBox">
  <Setter Property="gint:InteractivityItems.Template">
            <i:EventTrigger EventName="GotKeyboardFocus">
              <ei:CallMethodAction MethodName="SelectAll"/>
            <i:EventTrigger EventName="PreviewMouseLeftButtonDown">
              <ei:CallMethodAction MethodName="TextBox_PreviewMouseLeftButtonDown"
                TargetObject="{Binding ElementName=HostElementName}"/>

and this

public void TextBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
  TextBox tb = e.Source as TextBox;
  if((tb != null) && (tb.IsKeyboardFocusWithin == false))
    e.Handled = true;

In my case, I have a user control where the text boxes are that has a code-behind. The code-behind has the handler function. I gave my user control a name in XAML, and I am using that name for the element. This is working perfectly for me. Simply apply the style to any TextBox where you would like to have all the text selected when you click in the TextBox.

The first CallMethodAction calls the text box's SelectAll method when the GotKeyboardFocus event on the TextBox fires.

I hope this helps.

Convert a timedelta to days, hours and minutes

I used the following:

delta = timedelta()
totalMinute, second = divmod(delta.seconds, 60)
hour, minute = divmod(totalMinute, 60)

How to select last one week data from today's date

to select records for the last 7 days

WHERE Created_Date >= DATEADD(day, -7, GETDATE())

to select records for the current week

SET DATEFIRST 1 -- Define beginning of week as Monday

if you want to select records for last week instead of the last 7 days

SET DATEFIRST 1 -- Define beginning of week as Monday

Need to make a clickable <div> button

There are two solutions posted on that page. The one with lower votes I would recommend if possible.

If you are using HTML5 then it is perfectly valid to put a div inside of a. As long as the div doesn't also contain some other specific elements like other link tags.

<a href="Music.html">
  <div id="music" class="nav">
    Music I Like

The solution you are confused about actually makes the link as big as its container div. To make it work in your example you just need to add position: relative to your div. You also have a small syntax error which is that you have given the span a class instead of an id. You also need to put your span inside the link because that is what the user is clicking on. I don't think you need the z-index at all from that example.

div { position: relative; }
.hyperspan {

<div id="music" class="nav">Music I Like 
    <a href=""> 
        <span class="hyperspan"></span>

When you give absolute positioning to an element it bases its location and size after the first parent it finds that is relatively positioned. If none, then it uses the document. By adding relative to the parent div you tell the span to only be as big as that.

add new row in gridview after binding C#,

try using the cloning technique.

    DataGridViewRow row = (DataGridViewRow)yourdatagrid.Rows[0].Clone();
    // then for each of the values use a loop like below.
    int cc = yourdatagrid.Columns.Count;
    for (int i2 = 0; i < cc; i2++)
        row.Cells[i].Value = yourdatagrid.Rows[0].Cells[i].Value;

This should work. I'm not sure about how the binding works though. Hopefully it won't prevent this from working.

Password hash function for Excel VBA

Here's a module for calculating SHA1 hashes that is usable for Excel formulas eg. '=SHA1HASH("test")'. To use it, make a new module called 'module_sha1' and copy and paste it all in. This is based on some VBA code from, with changes to support passing it a string, and executable from formulas in Excel cells.

' Based on:
Option Explicit

Private Type FourBytes
    A As Byte
    B As Byte
    C As Byte
    D As Byte
End Type
Private Type OneLong
    L As Long
End Type

Function HexDefaultSHA1(Message() As Byte) As String
 Dim H1 As Long, H2 As Long, H3 As Long, H4 As Long, H5 As Long
 DefaultSHA1 Message, H1, H2, H3, H4, H5
 HexDefaultSHA1 = DecToHex5(H1, H2, H3, H4, H5)
End Function

Function HexSHA1(Message() As Byte, ByVal Key1 As Long, ByVal Key2 As Long, ByVal Key3 As Long, ByVal Key4 As Long) As String
 Dim H1 As Long, H2 As Long, H3 As Long, H4 As Long, H5 As Long
 xSHA1 Message, Key1, Key2, Key3, Key4, H1, H2, H3, H4, H5
 HexSHA1 = DecToHex5(H1, H2, H3, H4, H5)
End Function

Sub DefaultSHA1(Message() As Byte, H1 As Long, H2 As Long, H3 As Long, H4 As Long, H5 As Long)
 xSHA1 Message, &H5A827999, &H6ED9EBA1, &H8F1BBCDC, &HCA62C1D6, H1, H2, H3, H4, H5
End Sub

Sub xSHA1(Message() As Byte, ByVal Key1 As Long, ByVal Key2 As Long, ByVal Key3 As Long, ByVal Key4 As Long, H1 As Long, H2 As Long, H3 As Long, H4 As Long, H5 As Long)
 'CA62C1D68F1BBCDC6ED9EBA15A827999 + "abc" = "A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D"
 '"abc" = "A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D"

 Dim U As Long, P As Long
 Dim FB As FourBytes, OL As OneLong
 Dim i As Integer
 Dim W(80) As Long
 Dim A As Long, B As Long, C As Long, D As Long, E As Long
 Dim T As Long

 H1 = &H67452301: H2 = &HEFCDAB89: H3 = &H98BADCFE: H4 = &H10325476: H5 = &HC3D2E1F0

 U = UBound(Message) + 1: OL.L = U32ShiftLeft3(U): A = U \ &H20000000: LSet FB = OL 'U32ShiftRight29(U)

 ReDim Preserve Message(0 To (U + 8 And -64) + 63)
 Message(U) = 128

 U = UBound(Message)
 Message(U - 4) = A
 Message(U - 3) = FB.D
 Message(U - 2) = FB.C
 Message(U - 1) = FB.B
 Message(U) = FB.A

 While P < U
     For i = 0 To 15
         FB.D = Message(P)
         FB.C = Message(P + 1)
         FB.B = Message(P + 2)
         FB.A = Message(P + 3)
         LSet OL = FB
         W(i) = OL.L
         P = P + 4
     Next i

     For i = 16 To 79
         W(i) = U32RotateLeft1(W(i - 3) Xor W(i - 8) Xor W(i - 14) Xor W(i - 16))
     Next i

     A = H1: B = H2: C = H3: D = H4: E = H5

     For i = 0 To 19
         T = U32Add(U32Add(U32Add(U32Add(U32RotateLeft5(A), E), W(i)), Key1), ((B And C) Or ((Not B) And D)))
         E = D: D = C: C = U32RotateLeft30(B): B = A: A = T
     Next i
     For i = 20 To 39
         T = U32Add(U32Add(U32Add(U32Add(U32RotateLeft5(A), E), W(i)), Key2), (B Xor C Xor D))
         E = D: D = C: C = U32RotateLeft30(B): B = A: A = T
     Next i
     For i = 40 To 59
         T = U32Add(U32Add(U32Add(U32Add(U32RotateLeft5(A), E), W(i)), Key3), ((B And C) Or (B And D) Or (C And D)))
         E = D: D = C: C = U32RotateLeft30(B): B = A: A = T
     Next i
     For i = 60 To 79
         T = U32Add(U32Add(U32Add(U32Add(U32RotateLeft5(A), E), W(i)), Key4), (B Xor C Xor D))
         E = D: D = C: C = U32RotateLeft30(B): B = A: A = T
     Next i

     H1 = U32Add(H1, A): H2 = U32Add(H2, B): H3 = U32Add(H3, C): H4 = U32Add(H4, D): H5 = U32Add(H5, E)
End Sub

Function U32Add(ByVal A As Long, ByVal B As Long) As Long
 If (A Xor B) < 0 Then
     U32Add = A + B
     U32Add = (A Xor &H80000000) + B Xor &H80000000
 End If
End Function

Function U32ShiftLeft3(ByVal A As Long) As Long
 U32ShiftLeft3 = (A And &HFFFFFFF) * 8
 If A And &H10000000 Then U32ShiftLeft3 = U32ShiftLeft3 Or &H80000000
End Function

Function U32ShiftRight29(ByVal A As Long) As Long
 U32ShiftRight29 = (A And &HE0000000) \ &H20000000 And 7
End Function

Function U32RotateLeft1(ByVal A As Long) As Long
 U32RotateLeft1 = (A And &H3FFFFFFF) * 2
 If A And &H40000000 Then U32RotateLeft1 = U32RotateLeft1 Or &H80000000
 If A And &H80000000 Then U32RotateLeft1 = U32RotateLeft1 Or 1
End Function
Function U32RotateLeft5(ByVal A As Long) As Long
 U32RotateLeft5 = (A And &H3FFFFFF) * 32 Or (A And &HF8000000) \ &H8000000 And 31
 If A And &H4000000 Then U32RotateLeft5 = U32RotateLeft5 Or &H80000000
End Function
Function U32RotateLeft30(ByVal A As Long) As Long
 U32RotateLeft30 = (A And 1) * &H40000000 Or (A And &HFFFC) \ 4 And &H3FFFFFFF
 If A And 2 Then U32RotateLeft30 = U32RotateLeft30 Or &H80000000
End Function

Function DecToHex5(ByVal H1 As Long, ByVal H2 As Long, ByVal H3 As Long, ByVal H4 As Long, ByVal H5 As Long) As String
 Dim H As String, L As Long
 DecToHex5 = "00000000 00000000 00000000 00000000 00000000"
 H = Hex(H1): L = Len(H): Mid(DecToHex5, 9 - L, L) = H
 H = Hex(H2): L = Len(H): Mid(DecToHex5, 18 - L, L) = H
 H = Hex(H3): L = Len(H): Mid(DecToHex5, 27 - L, L) = H
 H = Hex(H4): L = Len(H): Mid(DecToHex5, 36 - L, L) = H
 H = Hex(H5): L = Len(H): Mid(DecToHex5, 45 - L, L) = H
End Function

' Convert the string into bytes so we can use the above functions
' From Chris Hulbert:

Public Function SHA1HASH(str)
  Dim i As Integer
  Dim arr() As Byte
  ReDim arr(0 To Len(str) - 1) As Byte
  For i = 0 To Len(str) - 1
   arr(i) = Asc(Mid(str, i + 1, 1))
  Next i
  SHA1HASH = Replace(LCase(HexDefaultSHA1(arr)), " ", "")
End Function

Else clause on Python while statement

The better use of 'while: else:' construction in Python should be if no loop is executed in 'while' then the 'else' statement is executed. The way it works today doesn't make sense because you can use the code below with the same results...

n = 5
while n != 0:
    print n
    n -= 1
print "what the..."

How to run SQL script in MySQL?

Since mysql -u yourusername -p yourpassword yourdatabase < text_file did not work on a remote server (Amazon's EC2)...

Make sure that the Database is created first.


mysql --host=localhost --user=your_username --password=your_password your_database_name < pathTofilename.sql

Understanding the main method of python

Python does not have a defined entry point like Java, C, C++, etc. Rather it simply executes a source file line-by-line. The if statement allows you to create a main function which will be executed if your file is loaded as the "Main" module rather than as a library in another module.

To be clear, this means that the Python interpreter starts at the first line of a file and executes it. Executing lines like class Foobar: and def foobar() creates either a class or a function and stores them in memory for later use.

Best practices for Storyboard login screen, handling clearing of data upon logout

Here's my Swifty solution for any future onlookers.

1) Create a protocol to handle both login and logout functions:

protocol LoginFlowHandler {
    func handleLogin(withWindow window: UIWindow?)
    func handleLogout(withWindow window: UIWindow?)

2) Extend said protocol and provide the functionality here for logging out:

extension LoginFlowHandler {

    func handleLogin(withWindow window: UIWindow?) {

        if let _ = AppState.shared.currentUserId {
            //User has logged in before, cache and continue
            self.showMainApp(withWindow: window)
        } else {
            //No user information, show login flow
            self.showLogin(withWindow: window)

    func handleLogout(withWindow window: UIWindow?) {


        showLogin(withWindow: window)

    func showLogin(withWindow window: UIWindow?) {
        window?.subviews.forEach { $0.removeFromSuperview() }
        window?.rootViewController = nil
        window?.rootViewController = R.storyboard.login.instantiateInitialViewController()

    func showMainApp(withWindow window: UIWindow?) {
        window?.rootViewController = nil
        window?.rootViewController = R.storyboard.mainTabBar.instantiateInitialViewController()


3) Then I can conform my AppDelegate to the LoginFlowHandler protocol, and call handleLogin on startup:

class AppDelegate: UIResponder, UIApplicationDelegate, LoginFlowHandler {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        window = UIWindow.init(frame: UIScreen.main.bounds)


        handleLogin(withWindow: window)

        return true


From here, my protocol extension will handle the logic or determining if the user if logged in/out, and then change the windows rootViewController accordingly!

How to watch for array changes?

The most upvoted Override push method solution by @canon has some side-effects that were inconvenient in my case:

  • It makes the push property descriptor different (writable and configurable should be set true instead of false), which causes exceptions in a later point.

  • It raises the event multiple times when push() is called once with multiple arguments (such as myArray.push("a", "b")), which in my case was unnecessary and bad for performance.

So this is the best solution I could find that fixes the previous issues and is in my opinion cleaner/simpler/easier to understand.

Object.defineProperty(myArray, "push", {
    configurable: true,
    enumerable: false,
    writable: true, // Previous values based on Object.getOwnPropertyDescriptor(Array.prototype, "push")
    value: function (...args)
        let result = Array.prototype.push.apply(this, args); // Original push() implementation based on and


        return result; // Original push() implementation

Please see comments for my sources and for hints on how to implement the other mutating functions apart from push: 'pop', 'shift', 'unshift', 'splice', 'sort', 'reverse'.

How to subtract X day from a Date object in Java?

You can easily subtract with calendar with SimpleDateFormat

 public static String subtractDate(String time,int subtractDay) throws ParseException {

        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm", Locale.ENGLISH);
        String wantedDate = sdf.format(cal.getTime());

        return wantedDate;


C#: Printing all properties of an object

Based on the ObjectDumper of the LINQ samples I created a version that dumps each of the properties on its own line.

This Class Sample

namespace MyNamespace
    public class User
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public Address Address { get; set; }
        public IList<Hobby> Hobbies { get; set; }

    public class Hobby
        public string Name { get; set; }

    public class Address
        public string Street { get; set; }
        public int ZipCode { get; set; }
        public string City { get; set; }    

has an output of

  FirstName: "Arnold"
  LastName: "Schwarzenegger"
  Address: { }
      Street: "6834 Hollywood Blvd"
      ZipCode: 90028
      City: "Hollywood"
  Hobbies: ...
      Name: "body building"

Here is the code.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Text;

public class ObjectDumper
    private int _level;
    private readonly int _indentSize;
    private readonly StringBuilder _stringBuilder;
    private readonly List<int> _hashListOfFoundElements;

    private ObjectDumper(int indentSize)
        _indentSize = indentSize;
        _stringBuilder = new StringBuilder();
        _hashListOfFoundElements = new List<int>();

    public static string Dump(object element)
        return Dump(element, 2);

    public static string Dump(object element, int indentSize)
        var instance = new ObjectDumper(indentSize);
        return instance.DumpElement(element);

    private string DumpElement(object element)
        if (element == null || element is ValueType || element is string)
            var objectType = element.GetType();
            if (!typeof(IEnumerable).IsAssignableFrom(objectType))
                Write("{{{0}}}", objectType.FullName);

            var enumerableElement = element as IEnumerable;
            if (enumerableElement != null)
                foreach (object item in enumerableElement)
                    if (item is IEnumerable && !(item is string))
                        if (!AlreadyTouched(item))
                            Write("{{{0}}} <-- bidirectional reference found", item.GetType().FullName);
                MemberInfo[] members = element.GetType().GetMembers(BindingFlags.Public | BindingFlags.Instance);
                foreach (var memberInfo in members)
                    var fieldInfo = memberInfo as FieldInfo;
                    var propertyInfo = memberInfo as PropertyInfo;

                    if (fieldInfo == null && propertyInfo == null)

                    var type = fieldInfo != null ? fieldInfo.FieldType : propertyInfo.PropertyType;
                    object value = fieldInfo != null
                                       ? fieldInfo.GetValue(element)
                                       : propertyInfo.GetValue(element, null);

                    if (type.IsValueType || type == typeof(string))
                        Write("{0}: {1}", memberInfo.Name, FormatValue(value));
                        var isEnumerable = typeof(IEnumerable).IsAssignableFrom(type);
                        Write("{0}: {1}", memberInfo.Name, isEnumerable ? "..." : "{ }");

                        var alreadyTouched = !isEnumerable && AlreadyTouched(value);
                        if (!alreadyTouched)
                            Write("{{{0}}} <-- bidirectional reference found", value.GetType().FullName);

            if (!typeof(IEnumerable).IsAssignableFrom(objectType))

        return _stringBuilder.ToString();

    private bool AlreadyTouched(object value)
        if (value == null)
            return false;

        var hash = value.GetHashCode();
        for (var i = 0; i < _hashListOfFoundElements.Count; i++)
            if (_hashListOfFoundElements[i] == hash)
                return true;
        return false;

    private void Write(string value, params object[] args)
        var space = new string(' ', _level * _indentSize);

        if (args != null)
            value = string.Format(value, args);

        _stringBuilder.AppendLine(space + value);

    private string FormatValue(object o)
        if (o == null)
            return ("null");

        if (o is DateTime)
            return (((DateTime)o).ToShortDateString());

        if (o is string)
            return string.Format("\"{0}\"", o);

        if (o is char && (char)o == '\0') 
            return string.Empty; 

        if (o is ValueType)
            return (o.ToString());

        if (o is IEnumerable)
            return ("...");

        return ("{ }");

and you can use it like that:

var dump = ObjectDumper.Dump(user);


  • Bi - directional references are now stopped. Therefore the HashCode of an object is stored in a list.
  • AlreadyTouched fixed (see comments)
  • FormatValue fixed (see comments)

How get value from URL

You can get that value by using the $_GET array. So the id value would be stored in $_GET['id'].

So in your case you could store that value in the $id variable as follows:

$id = $_GET['id'];

Using Java generics for JPA findAll() query with WHERE clause

Hat tip to Adam Bien if you don't want to use createQuery with a String and want type safety:

 EntityManager em;

 public List<ConfigurationEntry> allEntries() {
        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<ConfigurationEntry> cq = cb.createQuery(ConfigurationEntry.class);
        Root<ConfigurationEntry> rootEntry = cq.from(ConfigurationEntry.class);
        CriteriaQuery<ConfigurationEntry> all =;
        TypedQuery<ConfigurationEntry> allQuery = em.createQuery(all);
        return allQuery.getResultList();

How do I call a non-static method from a static method in C#?

You have to create an instance of that class within the static method and then call it.

For example like this:

public class MyClass
   private void data1()
   private static void data2()
     MyClass c = new MyClass();

Decode UTF-8 with Javascript

To answer the original question: here is how you decode utf-8 in javascript:


function encode_utf8(s) {
  return unescape(encodeURIComponent(s));

function decode_utf8(s) {
  return decodeURIComponent(escape(s));

We have been using this in our production code for 6 years, and it has worked flawlessly.

Note, however, that escape() and unescape() are deprecated. See this.

sklearn: Found arrays with inconsistent numbers of samples when calling

To analyze two arrays (array1 and array2) they need to meet the following two requirements:

1) They need to be a numpy.ndarray

Check with

# and

If that is not the case for at least one of them perform

array1 = numpy.ndarray(array1)
# or
array2 = numpy.ndarray(array2)

2) The dimensions need to be as follows:

array1.shape #shall give (N, 1)
array2.shape #shall give (N,)

N is the number of items that are in the array. To provide array1 with the right number of axes perform:

array1 = array1[:, numpy.newaxis]

What is the difference between varchar and varchar2 in Oracle?

Taken from the latest stable Oracle production version 12.2: Data Types

The major difference is that VARCHAR2 is an internal data type and VARCHAR is an external data type. So we need to understand the difference between an internal and external data type...

Inside a database, values are stored in columns in tables. Internally, Oracle represents data in particular formats known as internal data types.

In general, OCI (Oracle Call Interface) applications do not work with internal data type representations of data, but with host language data types that are predefined by the language in which they are written. When data is transferred between an OCI client application and a database table, the OCI libraries convert the data between internal data types and external data types.

External types provide a convenience for the programmer by making it possible to work with host language types instead of proprietary data formats. OCI can perform a wide range of data type conversions when transferring data between an Oracle database and an OCI application. There are more OCI external data types than Oracle internal data types.

The VARCHAR2 data type is a variable-length string of characters with a maximum length of 4000 bytes. If the init.ora parameter max_string_size is default, the maximum length of a VARCHAR2 can be 4000 bytes. If the init.ora parameter max_string_size = extended, the maximum length of a VARCHAR2 can be 32767 bytes

The VARCHAR data type stores character strings of varying length. The first 2 bytes contain the length of the character string, and the remaining bytes contain the string. The specified length of the string in a bind or a define call must include the two length bytes, so the largest VARCHAR string that can be received or sent is 65533 bytes long, not 65535.

A quick test in a 12.2 database suggests that as an internal data type, Oracle still treats a VARCHAR as a pseudotype for VARCHAR2. It is NOT a SYNONYM which is an actual object type in Oracle.

SQL> select substr(banner,1,80) from v$version where rownum=1;
Oracle Database 12c Enterprise Edition Release - 64bit Production    

SQL> create table test (my_char varchar(20));
Table created.

SQL> desc test
Name                 Null?    Type
MY_CHAR                       VARCHAR2(20)

There are also some implications of VARCHAR for ProC/C++ Precompiler options. For programmers who are interested, the link is at: Pro*C/C++ Programmer's Guide

WebSockets and Apache proxy : how to configure mod_proxy_wstunnel?

My setup:

  • Apache 2.4.10 (running off Debian)
  • Node.js (version 4.1.1) App running on port 3000 that accepts WebSockets at path /api/ws

As mentioned above by @Basj, make sure a2enmod proxy and ws_tunnel are enabled.

This is a screenshot of the Apache config file that solved my problem:

Apache config

The relevant part as text:

<VirtualHost *:80>
  ServerName *******
  ServerAlias *******
  ProxyPass / http://localhost:3000/
  ProxyPassReverse / http://localhost:3000/

  <Location "/api/ws">
      ProxyPass "ws://localhost:3000/api/ws"

Hope that helps.

Find the version of an installed npm package

If you agree to install jq, you can use the JSON output of npm list.

npm -j ls <package-name> | jq -r .version

or, if you want to be verbose

npm --json list <package-name> | jq --raw-output '.version'

For instance:

$ npm -j ls ghost | jq -r .version

Also, the JSON format is slightly different for global packages, so you'll need to change the query.

For instance:

$ npm -j -g ls | jq -r .dependencies.ghost.version

Last segment of URL in jquery

// = boo
// = boo
// = boo
// = boo

const segment = new 

Works for me.

Pip "Could not find a that satisfies the requirement"

pygame is not distributed via pip. See this link which provides windows binaries ready for installation.

  1. Install python
  2. Make sure you have python on your PATH
  3. Download the appropriate wheel from this link
  4. Install pip using this tutorial
  5. Finally, use these commands to install pygame wheel with pip

    • Python 2 (usually called pip)

      • pip install file.whl
    • Python 3 (usually called pip3)

      • pip3 install file.whl

Another tutorial for installing pygame for windows can be found here. Although the instructions are for 64bit windows, it can still be applied to 32bit

Git Remote: Error: fatal: protocol error: bad line length character: Unab

TL;DR: Do not omit username@ in your remote URLs when on Windows.

On Linux and on Windows with the default ssh, you can omit the username from remote URLs, like so:

git clone server-name:/srv/git/repo-name

Because ssh's default behavior is to just use whatever username you're currently logged in with. If you're on Windows and have set up git to use plink.exe so that you can use the key loaded in your pageant, then this will not work, because plink does not have this same automatic username behavior, resulting in those cryptic error messages, because it will prompt for the username:

$ plink server-name
login as: _


$ plink username@server-name
...logs you in...

If you already cloned a repository somehow you can fix the remotes in your .git/config by adding the username@ to the remote URL.

Can't install laravel installer via composer

zip extension is missing, You can avoid this error by simple running below command, It will take version by default

sudo apt-get install php-zip

In case you need any specific version, You need to mention a specific version of your php, Suppose I need to install X version of php-zip then the command will be.

sudo apt-get install phpX-zip  

Replace X with your required version, In my case, it is X = 7.3

Convert pandas data frame to series

It's not smart enough to realize it's still a "vector" in math terms.

Say rather that it's smart enough to recognize a difference in dimensionality. :-)

I think the simplest thing you can do is select that row positionally using iloc, which gives you a Series with the columns as the new index and the values as the values:

>>> df = pd.DataFrame([list(range(5))], columns=["a{}".format(i) for i in range(5)])
>>> df
   a0  a1  a2  a3  a4
0   0   1   2   3   4
>>> df.iloc[0]
a0    0
a1    1
a2    2
a3    3
a4    4
Name: 0, dtype: int64
>>> type(_)
<class 'pandas.core.series.Series'>

How to remove all of the data in a table using Django

Django 1.11 delete all objects from a database table -

Entry.objects.all().delete()  ## Entry being Model Name. 

Refer the Official Django documentation here as quoted below -

Note that delete() is the only QuerySet method that is not exposed on a Manager itself. This is a safety mechanism to prevent you from accidentally requesting Entry.objects.delete(), and deleting all the entries. If you do want to delete all the objects, then you have to explicitly request a complete query set:

I myself tried the code snippet seen below within my

    # for deleting model objects
    from django.db import connection
    def del_model_4(self):
        with connection.schema_editor() as schema_editor:

and within my i have a view that simply renders a html page ...

  def data_del_4(request):
      obj = calc_2() ## 
      return render(request, 'dc_dash/data_del_4.html') ## 

it ended deleting all entries from - model == model_4 , but now i get to see a Error screen within Admin console when i try to asceratin that all objects of model_4 have been deleted ...

ProgrammingError at /admin/dc_dash/model_4/
relation "dc_dash_model_4" does not exist
LINE 1: SELECT COUNT(*) AS "__count" FROM "dc_dash_model_4" 

Do consider that - if we do not go to the ADMIN Console and try and see objects of the model - which have been already deleted - the Django app works just as intended.

django admin screencapture

How to iterate std::set?

Just use the * before it:

set<unsigned long>::iterator it;
for (it = myset.begin(); it != myset.end(); ++it) {
    cout << *it;

This dereferences it and allows you to access the element the iterator is currently on.

mysql query result in php variable

I personally use prepared statements.

Why is it important?

Well it's important because of security. It's very easy to do an SQL injection on someone who use variables in the query.

Instead of using this code:

$query = "SELECT username,userid FROM user WHERE username = 'admin' ";

You should use this

$stmt = $this->db->query("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password); //You need the variables to do something as well.

Learn more about prepared statements on: MySQLI PDO

How to count TRUE values in a logical vector

Another way is

> length(z[z==TRUE])
[1] 498

While sum(z) is nice and short, for me length(z[z==TRUE]) is more self explaining. Though, I think with a simple task like this it does not really make a difference...

If it is a large vector, you probably should go with the fastest solution, which is sum(z). length(z[z==TRUE]) is about 10x slower and table(z)[TRUE] is about 200x slower than sum(z).

Summing up, sum(z) is the fastest to type and to execute.