Programs & Examples On #Jquery chaining

how to print json data in console.log

To output an object to the console, you have to stringify the object first:

success:function(data){
     console.log(JSON.stringify(data));
}

Specifying row names when reading in a file

If you used read.table() (or one of it's ilk, e.g. read.csv()) then the easy fix is to change the call to:

read.table(file = "foo.txt", row.names = 1, ....)

where .... are the other arguments you needed/used. The row.names argument takes the column number of the data file from which to take the row names. It need not be the first column. See ?read.table for details/info.

If you already have the data in R and can't be bothered to re-read it, or it came from another route, just set the rownames attribute and remove the first variable from the object (assuming obj is your object)

rownames(obj) <- obj[, 1]  ## set rownames
obj <- obj[, -1]           ## remove the first variable

What is default session timeout in ASP.NET?

It is 20 Minutes according to MSDN

From MSDN:

Optional TimeSpan attribute.

Specifies the number of minutes a session can be idle before it is abandoned. The timeout attribute cannot be set to a value that is greater than 525,601 minutes (1 year) for the in-process and state-server modes. The session timeout configuration setting applies only to ASP.NET pages. Changing the session timeout value does not affect the session time-out for ASP pages. Similarly, changing the session time-out for ASP pages does not affect the session time-out for ASP.NET pages. The default is 20 minutes.

Error: JAVA_HOME is not defined correctly executing maven

Assuming you use bash shell and installed Java with the Oracle installer, you could add the following to your .bash_profile

export JAVA_HOME=$(/usr/libexec/java_home)
export PATH=$JAVA_HOME/jre/bin:$PATH

This would pick the correct JAVA_HOME as defined by the Oracle installer and will set it first in your $PATH making sure it is found.

Also, you don't need to change it later when updating Java.

EDIT

As per the comments:

Making it persistent after a reboot

Just add those lines in the shell configuration file. (Assuming it's bash)

Ex: .bashrc, .bash_profile or .profile (for ubuntu)

Using a custom Java installation

Set JAVA_HOME to the root folder of the custom Java installation path without the $().

Ex: JAVA_HOME=/opt/java/openjdk

Send password when using scp to copy files from one server to another

// copy /tmp/abc.txt to /tmp/abc.txt (target path)

// username and password of 10.1.1.2 is "username" and "password"

sshpass -p "password" scp /tmp/abc.txt [email protected]:/tmp/abc.txt

// install sshpass (ubuntu)

sudo apt-get install sshpass

Return rows in random order

To be efficient, and random, it might be best to have two different queries.

Something like...

SELECT table_id FROM table

Then, in your chosen language, pick a random id, then pull that row's data.

SELECT * FROM table WHERE table_id = $rand_id

But that's not really a good idea if you're expecting to have lots of rows in the table. It would be better if you put some kind of limit on what you randomly select from. For publications, maybe randomly pick from only items posted within the last year.

What's the best way to detect a 'touch screen' device using JavaScript?

If you use Modernizr, it is very easy to use Modernizr.touch as mentioned earlier.

However, I prefer using a combination of Modernizr.touch and user agent testing, just to be safe.

var deviceAgent = navigator.userAgent.toLowerCase();

var isTouchDevice = Modernizr.touch || 
(deviceAgent.match(/(iphone|ipod|ipad)/) ||
deviceAgent.match(/(android)/)  || 
deviceAgent.match(/(iemobile)/) || 
deviceAgent.match(/iphone/i) || 
deviceAgent.match(/ipad/i) || 
deviceAgent.match(/ipod/i) || 
deviceAgent.match(/blackberry/i) || 
deviceAgent.match(/bada/i));

if (isTouchDevice) {
        //Do something touchy
    } else {
        //Can't touch this
    }

If you don't use Modernizr, you can simply replace the Modernizr.touch function above with ('ontouchstart' in document.documentElement)

Also note that testing the user agent iemobile will give you broader range of detected Microsoft mobile devices than Windows Phone.

Also see this SO question

Make a DIV fill an entire table cell

If the table cell is the size that you want, just add this css class and assign it to your div:

.block {
   height: -webkit-calc(100vh);
   height: -moz-calc(100vh);
   height: calc(100vh);
   width: 100%;
}

If you want the table cell to fill up the parent too, assign the class to table cell too. I hope it helps.

How to search multiple columns in MySQL?

You can use the AND or OR operators, depending on what you want the search to return.

SELECT title FROM pages WHERE my_col LIKE %$param1% AND another_col LIKE %$param2%;

Both clauses have to match for a record to be returned. Alternatively:

SELECT title FROM pages WHERE my_col LIKE %$param1% OR another_col LIKE %$param2%;

If either clause matches then the record will be returned.

For more about what you can do with MySQL SELECT queries, try the documentation.

How to set multiple commands in one yaml file with Kubernetes?

If you're willing to use a Volume and a ConfigMap, you can mount ConfigMap data as a script, and then run that script:

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-configmap
data:
  entrypoint.sh: |-
    #!/bin/bash
    echo "Do this"

    echo "Do that"
---
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: my-container
    image: "ubuntu:14.04"
    command:
    - /bin/entrypoint.sh
    volumeMounts:
    - name: configmap-volume
      mountPath: /bin/entrypoint.sh
      readOnly: true
      subPath: entrypoint.sh
  volumes:
  - name: configmap-volume
    configMap:
      defaultMode: 0700
      name: my-configmap

This cleans up your pod spec a little and allows for more complex scripting.

$ kubectl logs my-pod
Do this
Do that

Error: Cannot pull with rebase: You have unstaged changes

This works for me:

git fetch
git rebase --autostash FETCH_HEAD

How to delete an object by id with entity framework

I am using the following code in one of my projects:

    using (var _context = new DBContext(new DbContextOptions<DBContext>()))
    {
        try
        {
            _context.MyItems.Remove(new MyItem() { MyItemId = id });
            await _context.SaveChangesAsync();
        }
        catch (Exception ex)
        {
            if (!_context.MyItems.Any(i => i.MyItemId == id))
            {
                return NotFound();
            }
            else
            {
                throw ex;
            }
        }
    }

This way, it will query the database twice only if an exception occurs when trying to remove the item with the specified ID. Then if the item is not found, it returns a meaningful message; otherwise, it just throws the exception back (you can handle this in a way more fit to your case using different catch blocks for different exception types, add more custom checks using if blocks etc.).

[I am using this code in a MVC .Net Core/.Net Core project with Entity Framework Core.]

C# - Simplest way to remove first occurrence of a substring from another string

If you'd like a simple method to resolve this problem. (Can be used as an extension)

See below:

    public static string RemoveFirstInstanceOfString(this string value, string removeString)
    {
        int index = value.IndexOf(removeString, StringComparison.Ordinal);
        return index < 0 ? value : value.Remove(index, removeString.Length);
    }

Usage:

    string valueWithPipes = "| 1 | 2 | 3";
    string valueWithoutFirstpipe = valueWithPipes.RemoveFirstInstanceOfString("|");
    //Output, valueWithoutFirstpipe = " 1 | 2 | 3";

Inspired by and modified @LukeH's and @Mike's answer.

Don't forget the StringComparison.Ordinal to prevent issues with Culture settings. https://www.jetbrains.com/help/resharper/2018.2/StringIndexOfIsCultureSpecific.1.html

Display date in dd/mm/yyyy format in vb.net

You could decompose the date into it's constituent parts and then concatenate them together like this:

MsgBox(Now.Day & "/" & Now.Month & "/" & Now.Year)

How to list running screen sessions?

So you're using screen to keep the experiments running in the background, or what? If so, why not just start it in the background?

./experiment &

And if you're asking how to get notification the job i done, how about stringing the experiment together with a mail command?

./experiment && echo "the deed is done" | mail youruser@yourlocalworkstation -s "job on server $HOSTNAME is done"

Call to undefined method mysqli_stmt::get_result

I realize that it's been a while since there has been any new activity on this question. But, as other posters have commented - get_result() is now only available in PHP by installing the MySQL native driver (mysqlnd), and in some cases, it may not be possible or desirable to install mysqlnd. So, I thought it would be helpful to post this answer with info on how get the functionality that get_result() offers - without using get_result().

get_result() is/was often combined with fetch_array() to loop through a result set and store the values from each row of the result set in a numerically-indexed or associative array. For example, the code below uses get_result() with fetch_array() to loop through a result set, storing the values from each row in the numerically-indexed $data[] array:

$c=1000;
$sql="select account_id, username from accounts where account_id<?";
$stmt = $mysqli->prepare($sql);                 
$stmt->bind_param('i', $c);                                             
$stmt->execute();
$result = $stmt->get_result();       
while($data = $result->fetch_array(MYSQLI_NUM)) {
   print $data[0] . ', ' . $data[1] . "<BR>\n"; 
}

However, if get_result() is not available (because mysqlnd is not installed), then this leads to the problem of how to store the values from each row of a result set in an array, without using get_result(). Or, how to migrate legacy code that uses get_result() to run without it (e.g. using bind_result() instead) - while impacting the rest of the code as little as possible.

It turns out that storing the values from each row in a numerically-indexed array is not so straight-forward using bind_result(). bind_result() expects a list of scalar variables (not an array). So, it takes some doing to make it store the values from each row of the result set in an array.

Of course, the code could easily be modified as follows:

$c=1000;
$sql="select account_id, username from accounts where account_id<?";
$stmt = $mysqli->prepare($sql);                 
$stmt->bind_param('i', $c);                                             
$stmt->execute();
$stmt->bind_result($data[0], $data[1]);
while ($stmt->fetch()) {
   print $data[0] . ', ' . $data[1] . "<BR>\n"; 
}

But, this requires us to explicitly list $data[0], $data[1], etc. individually in the call to bind_result(), which is not ideal. We want a solution that doesn't require us to have to explicitly list $data[0], $data[1], ... $data[N-1] (where N is the number of fields in the select statement) in the call to bind_results(). If we're migrating a legacy application that has a large number of queries, and each query may contain a different number of fields in the select clause, the migration will be very labor intensive and prone to error if we use a solution like the one above.

Ideally, we want a snippet of 'drop-in replacement' code - to replace just the line containing the get_result() function and the while() loop on the next line. The replacement code should have the same function as the code that it's replacing, without affecting any of the lines before, or any of the lines after - including the lines inside the while() loop. Ideally we want the replacement code to be as compact as possible, and we don't want to have to taylor the replacement code based on the number of fields in the select clause of the query.

Searching on the internet, I found a number of solutions that use bind_param() with call_user_func_array() (for example, Dynamically bind mysqli_stmt parameters and then bind result (PHP)), but most solutions that I found eventually lead to the results being stored in an associative array, not a numerically-indexed array, and many of these solutions were not as compact as I would like and/or were not suited as 'drop-in replacements'. However, from the examples that I found, I was able to cobble together this solution, which fits the bill:

$c=1000;
$sql="select account_id, username from accounts where account_id<?";
$stmt = $mysqli->prepare($sql);                 
$stmt->bind_param('i', $c);                                             
$stmt->execute();
$data=array();
for ($i=0;$i<$mysqli->field_count;$i++) { 
    $var = $i;
    $$var = null; 
    $data[$var] = &$$var; 
}
call_user_func_array(array($stmt,'bind_result'), $data);
while ($stmt->fetch()) {
   print $data[0] . ', ' . $data[1] . "<BR>\n"; 
}

Of course, the for() loop can be collapsed into one line to make it more compact.

I hope this helps anyone who is looking for a solution using bind_result() to store the values from each row in a numerically-indexed array and/or looking for a way to migrate legacy code using get_result(). Comments welcome.

Selecting multiple items in ListView

Best way is to have a contextual action bar with listview on multiselect, You can make listview as multiselect using the following code

listview.setChoiceMode(AbsListView.CHOICE_MODE_MULTIPLE_MODAL);

And now set multichoice listener for Listview ,You can see the complete implementation of multiselect listview at Android multi select listview

How can I convert bigint (UNIX timestamp) to datetime in SQL Server?

For GMT, here is the easiest way:

Select dateadd(s, @UnixTime+DATEDIFF (S, GETUTCDATE(), GETDATE()), '1970-01-01')

Add custom headers to WebView resource requests - android

I came accross the same problem and solved.

As said before you need to create your custom WebViewClient and override the shouldInterceptRequest method.

WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request)

That method should issue a webView.loadUrl while returning an "empty" WebResourceResponse.

Something like this:

@Override
public boolean shouldInterceptRequest(WebView view, WebResourceRequest request) {

    // Check for "recursive request" (are yor header set?)
    if (request.getRequestHeaders().containsKey("Your Header"))
        return null;

    // Add here your headers (could be good to import original request header here!!!)
    Map<String, String> customHeaders = new HashMap<String, String>();
    customHeaders.put("Your Header","Your Header Value");
    view.loadUrl(url, customHeaders);

    return new WebResourceResponse("", "", null);
}

How is the 'use strict' statement interpreted in Node.js?

"use strict";

Basically it enables the strict mode.

Strict Mode is a feature that allows you to place a program, or a function, in a "strict" operating context. In strict operating context, the method form binds this to the objects as before. The function form binds this to undefined, not the global set objects.

As per your comments you are telling some differences will be there. But it's your assumption. The Node.js code is nothing but your JavaScript code. All Node.js code are interpreted by the V8 JavaScript engine. The V8 JavaScript Engine is an open source JavaScript engine developed by Google for Chrome web browser.

So, there will be no major difference how "use strict"; is interpreted by the Chrome browser and Node.js.

Please read what is strict mode in JavaScript.

For more information:

  1. Strict mode
  2. ECMAScript 5 Strict mode support in browsers
  3. Strict mode is coming to town
  4. Compatibility table for strict mode
  5. Stack Overflow questions: what does 'use strict' do in JavaScript & what is the reasoning behind it


ECMAScript 6:

ECMAScript 6 Code & strict mode. Following is brief from the specification:

10.2.1 Strict Mode Code

An ECMAScript Script syntactic unit may be processed using either unrestricted or strict mode syntax and semantics. Code is interpreted as strict mode code in the following situations:

  • Global code is strict mode code if it begins with a Directive Prologue that contains a Use Strict Directive (see 14.1.1).
  • Module code is always strict mode code.
  • All parts of a ClassDeclaration or a ClassExpression are strict mode code.
  • Eval code is strict mode code if it begins with a Directive Prologue that contains a Use Strict Directive or if the call to eval is a direct eval (see 12.3.4.1) that is contained in strict mode code.
  • Function code is strict mode code if the associated FunctionDeclaration, FunctionExpression, GeneratorDeclaration, GeneratorExpression, MethodDefinition, or ArrowFunction is contained in strict mode code or if the code that produces the value of the function’s [[ECMAScriptCode]] internal slot begins with a Directive Prologue that contains a Use Strict Directive.
  • Function code that is supplied as the arguments to the built-in Function and Generator constructors is strict mode code if the last argument is a String that when processed is a FunctionBody that begins with a Directive Prologue that contains a Use Strict Directive.

Additionally if you are lost on what features are supported by your current version of Node.js, this node.green can help you (leverages from the same data as kangax).

What is the SQL command to return the field names of a table?

If you just want the column names, then

select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'tablename'

On MS SQL Server, for more information on the table such as the types of the columns, use

sp_help 'tablename'

How to hide the Google Invisible reCAPTCHA badge

If you are using the Contact Form 7 update and the latest version (version 5.1.x), you will need to install, setup Google reCAPTCHA v3 to use.

by default you get Google reCAPTCHA logo displayed on every page on the bottom right of the screen. This is according to our assessment is creating a bad experience for users. And your website, blog will slow down a bit (reflect by PageSpeed Score), by your website will have to load additional 1 JavaScript library from Google to display this badge.

You can hide Google reCAPTCHA v3 from CF7 (only show it when necessary) by following these steps:

First, you open the functions.php file of your theme (using File Manager or FTP Client). This file is locate in: /wp-content/themes/your-theme/ and add the following snippet (we’re using this code to remove reCAPTCHA box on every page):

    remove_action( 'wp_enqueue_scripts', 'wpcf7_recaptcha_enqueue_scripts' );

Next, you will add this snippet in the page you want it to display Google reCAPTCHA (contact page, login, register page …):

if ( function_exists( 'wpcf7_enqueue_scripts' ) ) {
    add_action( 'wp_enqueue_scripts', 'wpcf7_recaptcha_enqueue_scripts', 10, 0 );
}

Refer on OIW Blog - How To Remove Google reCAPTCHA Logo from Contact Form 7 in WordPress (Hide reCAPTCHA badge)

Stupid error: Failed to load resource: net::ERR_CACHE_MISS

Google declares that this is not a failure, but some "misleading error reports". This bug will be fixed in version 40 of chrome.

You can read this:

Chromium forum
Chromium forum
Patch

Android: How to add R.raw to project?

Create a raw android resource directory. enter image description here

Once the raw directory is created, Make sure to add a valid media file

  1. Make sure to follow proper naming conventions (lower case letters with underscore '_' as separators)
  2. Media file should have a proper encoding and formatted media file in one of the supported formats.

After following the above procedure, you should be able to access your media files by using R.raw.media_file

Interface defining a constructor signature?

One way to force some sort of constructor is to declare only Getters in interface, which could then mean that the implementing class must have a method, ideally a constructor, to have the value set (privately) for it.

200 PORT command successful. Consider using PASV. 425 Failed to establish connection

Try using the passive command before using ls.

From FTP client, to check if the FTP server supports passive mode, after login, type quote PASV.

Following are connection examples to a vsftpd server with passive mode on and off

vsftpd with pasv_enable=NO:

# ftp localhost
Connected to localhost.localdomain.
220 (vsFTPd 2.3.5)
Name (localhost:john): anonymous
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> quote PASV
550 Permission denied.
ftp> 

vsftpd with pasv_enable=YES:

# ftp localhost
Connected to localhost.localdomain.
220 (vsFTPd 2.3.5)
Name (localhost:john): anonymous
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> quote PASV
227 Entering Passive Mode (127,0,0,1,173,104).
ftp> 

Can I use wget to check , but not download

If you want to check quietly via $? without the hassle of grep'ing wget's output you can use:

wget -q "http://blah.meh.com/my/path" -O /dev/null

Works even on URLs with just a path but has the disadvantage that something's really downloaded so this is not recommended when checking big files for existence.

'namespace' but is used like a 'type'

namespace TestApplication // Remove .Controller
{
    public class HomeController : Controller
    {
       public ActionResult Index()
        {
            return View();
        }
    }
}

Remove the controller word from namepsace

How to get json key and value in javascript?

http://jsfiddle.net/v8aWF/

Worked out a fiddle. Do check it out

(function() {
    var oJson = {
        "name": "", 
        "skills": "", 
        "jobtitle": "Entwickler", 
        "res_linkedin": "GwebSearch"
    }
    alert(oJson.jobtitle);
})();

unexpected T_VARIABLE, expecting T_FUNCTION

check that you entered a variable as argument with the '$' symbol

How to pad zeroes to a string?

Just use the rjust method of the string object.

This example will make a string of 10 characters long, padding as necessary.

>>> t = 'test'
>>> t.rjust(10, '0')
>>> '000000test'

Java: how do I initialize an array size if it's unknown?

I agree that a data structure like a List is the best way to go:

List<Integer> values = new ArrayList<Integer>();
Scanner in = new Scanner(System.in);
int value;
int numValues = 0;
do {
    value = in.nextInt();
    values.add(value);
} while (value >= 1) && (value <= 100);

Or you can just allocate an array of a max size and load values into it:

int maxValues = 100;
int [] values = new int[maxValues];
Scanner in = new Scanner(System.in);
int value;
int numValues = 0;
do {
    value = in.nextInt();
    values[numValues++] = value;
} while (value >= 1) && (value <= 100) && (numValues < maxValues);

Eclipse - Installing a new JRE (Java SE 8 1.8.0)

You can have many java versions in your system.

I think you should add the java 8 in yours JREs installed or edit.

Take a look my screen:

enter image description here

If you click in edit (check your java 8 path):

enter image description here

Using HttpClient and HttpPost in Android with post parameters

have you tried doing it without the JSON object and just passed two basicnamevaluepairs? also, it might have something to do with your serversettings

Update: this is a piece of code I use:

InputStream is = null;
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("lastupdate", lastupdate)); 

try {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(connection);
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();
        Log.d("HTTP", "HTTP: OK");
    } catch (Exception e) {
        Log.e("HTTP", "Error in http connection " + e.toString());
    }

How to convert a string with comma-delimited items to a list in Python?

# to strip `,` and `.` from a string ->

>>> 'a,b,c.'.translate(None, ',.')
'abc'

You should use the built-in translate method for strings.

Type help('abc'.translate) at Python shell for more info.

Specified cast is not valid?

Try this:

public void LoadData()
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Stocks;Integrated Security=True;Pooling=False");
            SqlDataAdapter sda = new SqlDataAdapter("Select * From [Stocks].[dbo].[product]", con);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            DataGridView1.Rows.Clear();

        foreach (DataRow item in dt.Rows)
        {
            int n = DataGridView1.Rows.Add();
            DataGridView1.Rows[n].Cells[0].Value = item["ProductCode"].ToString();
            DataGridView1.Rows[n].Cells[1].Value = item["Productname"].ToString();
            DataGridView1.Rows[n].Cells[2].Value = item["qty"].ToString();                
            if ((bool)item["productstatus"])
            {
                DataGridView1.Rows[n].Cells[3].Value = "Active";
            }
            else
            {
                DataGridView1.Rows[n].Cells[3].Value = "Deactive";
            }

sql query to return differences between two tables

There is a performance issue related with the left join as well as full join with large data.

In my opinion this is the best solution:

select [First Name], count(1) e from (select * from [Temp Test Data] union all select * from [Temp Test Data 2]) a group by [First Name] having e = 1

android edittext onchange listener

First, you can see if the user finished editing the text if the EditText loses focus or if the user presses the done button (this depends on your implementation and on what fits the best for you). Second, you can't get an EditText instance within the TextWatcher only if you have declared the EditText as an instance object. Even though you shouldn't edit the EditText within the TextWatcher because it is not safe.

EDIT:

To be able to get the EditText instance into your TextWatcher implementation, you should try something like this:

public class YourClass extends Activity {

    private EditText yourEditText;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);
        yourEditText = (EditText) findViewById(R.id.yourEditTextId);

        yourEditText.addTextChangedListener(new TextWatcher() {

            public void afterTextChanged(Editable s) {

                // you can call or do what you want with your EditText here

                // yourEditText... 
            }

            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

            public void onTextChanged(CharSequence s, int start, int before, int count) {}
        });
    }
}

Note that the above sample might have some errors but I just wanted to show you an example.

Get everything after and before certain character in SQL Server

 declare @T table
  (
  Col varchar(20)
  )



  insert into @T 
  Select 'images/test1.jpg'
  union all
  Select 'images/test2.png'
  union all
  Select 'images/test3.jpg'
  union all
  Select 'images/test4.jpeg'
  union all
  Select 'images/test5.jpeg'

 Select substring( LEFT(Col,charindex('.',Col)-1),charindex('/',Col)+1,len(LEFT(Col,charindex('.',Col)-1))-1 )
from @T

How to set the range of y-axis for a seaborn boxplot?

It is standard matplotlib.pyplot:

...
import matplotlib.pyplot as plt
plt.ylim(10, 40)

Or simpler, as mwaskom comments below:

ax.set(ylim=(10, 40))

enter image description here

How to sanity check a date in Java

Key is df.setLenient(false);. This is more than enough for simple cases. If you are looking for a more robust (I doubt) and/or alternate libraries like joda-time then look at the answer by the user "tardate"

final static String DATE_FORMAT = "dd-MM-yyyy";

public static boolean isDateValid(String date) 
{
        try {
            DateFormat df = new SimpleDateFormat(DATE_FORMAT);
            df.setLenient(false);
            df.parse(date);
            return true;
        } catch (ParseException e) {
            return false;
        }
}

How can I read a whole file into a string variable

I'm not with computer,so I write a draft. You might be clear of what I say.

func main(){
    const dir = "/etc/"
    filesInfo, e := ioutil.ReadDir(dir)
    var fileNames = make([]string, 0, 10)
    for i,v:=range filesInfo{
        if !v.IsDir() {
            fileNames = append(fileNames, v.Name())
        }
    }

    var fileNumber = len(fileNames)
    var contents = make([]string, fileNumber, 10)
    wg := sync.WaitGroup{}
    wg.Add(fileNumber)

    for i,_:=range content {
        go func(i int){
            defer wg.Done()
            buf,e := ioutil.Readfile(fmt.Printf("%s/%s", dir, fileName[i]))
            defer file.Close()  
            content[i] = string(buf)
        }(i)   
    }
    wg.Wait()
}

How to select the first element in the dropdown using jquery?

What you want is probably:

$("select option:first-child")

What this code

attr("selected", "selected");

is doing is setting the "selected" attribute to "selected"

If you want the selected options, regardless of whether it is the first-child, the selector is:

$("select").children("[selected]")

Why use 'git rm' to remove a file instead of 'rm'?

When using git rm, the removal will part of your next commit. So if you want to push the change you should use git rm

How to "git show" a merge commit with combined diff output even when every changed file agrees with one of the parents?

If your merge commit is commit 0e1329e5, as above, you can get the diff that was contained in this merge by:

git diff 0e1329e5^..0e1329e5

I hope this helps!

What does ellipsize mean in android?

here is an example on how ellipsize works without using deprecated android:singleLine="true" in a ConstraintLayout:

<TextView
   android:layout_width="0dp"
   android:layout_height="wrap_content"
   android:textSize="13sp"
   android:ellipsize="end"
   android:maxLines="2"
   app:layout_constraintEnd_toEndOf="parent"
   app:layout_constraintStart_toStartOf="parent"
   tools:text="long long long long long long text text text" />

remember if you have a text that is supposed to be in a single line, then change the maxLines to 1.

How to select an element by classname using jqLite?

If elem.find() is not working for you, check that you are including JQuery script before angular script....

understanding private setters

I don't understand the need of having private setters which started with C# 2.

For example, the invoice class allows the user to add or remove items from the Items property but it does not allow the user from changing the Items reference (ie, the user cannot assign Items property to another item list object instance).


public class Item
{
  public string item_code;
  public int qty;

  public Item(string i, int q)
  {
    this.item_code = i;
    this.qty = q;
  }
}

public class Invoice
{
  public List Items { get; private set; }

  public Invoice()
  {
    this.Items = new List();
  }
}

public class TestInvoice
{
  public void Test()
  {
    Invoice inv = new Invoice();
    inv.Items.Add(new Item("apple", 10));

    List my_items = new List();
    my_items.Add(new Item("apple", 10));

    inv.Items = my_items;   // compilation error here.
  }
}

How to specify non-default shared-library path in GCC Linux? Getting "error while loading shared libraries" when running

There are two ways to achieve that:

  • Use -rpath linker option:

gcc XXX.c -o xxx.out -L$HOME/.usr/lib -lXX -Wl,-rpath=/home/user/.usr/lib

  • Use LD_LIBRARY_PATH environment variable - put this line in your ~/.bashrc file:

    export LD_LIBRARY_PATH=/home/user/.usr/lib

This will work even for a pre-generated binaries, so you can for example download some packages from the debian.org, unpack the binaries and shared libraries into your home directory, and launch them without recompiling.

For a quick test, you can also do (in bash at least):

LD_LIBRARY_PATH=/home/user/.usr/lib ./xxx.out

which has the advantage of not changing your library path for everything else.

How can I see all the "special" characters permissible in a varchar or char field in SQL Server?

EDIT based on comments:

If you have line breaks in your result set and want to remove them, make your query this way:

SELECT
    REPLACE(REPLACE(YourColumn1,CHAR(13),' '),CHAR(10),' ')
   ,REPLACE(REPLACE(YourColumn2,CHAR(13),' '),CHAR(10),' ')
   ,REPLACE(REPLACE(YourColumn3,CHAR(13),' '),CHAR(10),' ')
   --^^^^^^^^^^^^^^^           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   --only add the above code to strings that are having line breaks, not to numbers or dates
   FROM YourTable...
   WHERE ...

This will replace all the line breaks with a space character.

Run this to "get" all characters permitted in a char() and varchar():

;WITH AllNumbers AS
(
    SELECT 1 AS Number
    UNION ALL
    SELECT Number+1
        FROM AllNumbers
        WHERE Number+1<256
)
SELECT Number AS ASCII_Value,CHAR(Number) AS ASCII_Char FROM AllNumbers
OPTION (MAXRECURSION 256)

OUTPUT:

ASCII_Value ASCII_Char
----------- ----------
1           
2           
3           
4           
5           
6           
7           
8           
9               
10          

11          
12          
13          

14          
15          
16          
17          
18          
19          
20          
21          
22          
23          
24          
25          
26          
27          
28          
29          
30          
31          
32           
33          !
34          "
35          #
36          $
37          %
38          &
39          '
40          (
41          )
42          *
43          +
44          ,
45          -
46          .
47          /
48          0
49          1
50          2
51          3
52          4
53          5
54          6
55          7
56          8
57          9
58          :
59          ;
60          <
61          =
62          >
63          ?
64          @
65          A
66          B
67          C
68          D
69          E
70          F
71          G
72          H
73          I
74          J
75          K
76          L
77          M
78          N
79          O
80          P
81          Q
82          R
83          S
84          T
85          U
86          V
87          W
88          X
89          Y
90          Z
91          [
92          \
93          ]
94          ^
95          _
96          `
97          a
98          b
99          c
100         d
101         e
102         f
103         g
104         h
105         i
106         j
107         k
108         l
109         m
110         n
111         o
112         p
113         q
114         r
115         s
116         t
117         u
118         v
119         w
120         x
121         y
122         z
123         {
124         |
125         }
126         ~
127         
128         €
129         
130         ‚
131         ƒ
132         „
133         …
134         †
135         ‡
136         ˆ
137         ‰
138         Š
139         ‹
140         Œ
141         
142         Ž
143         
144         
145         ‘
146         ’
147         “
148         ”
149         •
150         –
151         —
152         ˜
153         ™
154         š
155         ›
156         œ
157         
158         ž
159         Ÿ
160          
161         ¡
162         ¢
163         £
164         ¤
165         ¥
166         ¦
167         §
168         ¨
169         ©
170         ª
171         «
172         ¬
173         ­
174         ®
175         ¯
176         °
177         ±
178         ²
179         ³
180         ´
181         µ
182         ¶
183         ·
184         ¸
185         ¹
186         º
187         »
188         ¼
189         ½
190         ¾
191         ¿
192         À
193         Á
194         Â
195         Ã
196         Ä
197         Å
198         Æ
199         Ç
200         È
201         É
202         Ê
203         Ë
204         Ì
205         Í
206         Î
207         Ï
208         Ð
209         Ñ
210         Ò
211         Ó
212         Ô
213         Õ
214         Ö
215         ×
216         Ø
217         Ù
218         Ú
219         Û
220         Ü
221         Ý
222         Þ
223         ß
224         à
225         á
226         â
227         ã
228         ä
229         å
230         æ
231         ç
232         è
233         é
234         ê
235         ë
236         ì
237         í
238         î
239         ï
240         ð
241         ñ
242         ò
243         ó
244         ô
245         õ
246         ö
247         ÷
248         ø
249         ù
250         ú
251         û
252         ü
253         ý
254         þ
255         ÿ

(255 row(s) affected)

How to plot a very simple bar chart (Python, Matplotlib) using input *.txt file?

This code will do what you're looking for. It's based on examples found here and here.

The autofmt_xdate() call is particularly useful for making the x-axis labels readable.

import numpy as np
from matplotlib import pyplot as plt

fig = plt.figure()

width = .35
ind = np.arange(len(OY))
plt.bar(ind, OY, width=width)
plt.xticks(ind + width / 2, OX)

fig.autofmt_xdate()

plt.savefig("figure.pdf")

enter image description here

Objective-C and Swift URL encoding

//use NSString instance method like this:

+ (NSString *)encodeURIComponent:(NSString *)string
{
NSString *s = [string stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
return s;
}

+ (NSString *)decodeURIComponent:(NSString *)string
{
NSString *s = [string stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
return s;
}

remember,you should only do encode or decode for your parameter value, not all the url you request.

CSS: Background image and padding

setting direction CSS property to rtl should work with you. I guess it isn't supported on IE6.

e.g

<ul style="direction:rtl;">
<li> item </li>
<li> item </li>
</ul>

How to use awk sort by column 3

Seeing as that the original question was on how to use awk and every single one of the first 7 answers use sort instead, and that this is the top hit on Google, here is how to use awk.

Sample net.csv file with headers:

ip,hostname,user,group,encryption,aduser,adattr
192.168.0.1,gw,router,router,-,-,-
192.168.0.2,server,admin,admin,-,-,-
192.168.0.3,ws-03,user,user,-,-,-
192.168.0.4,ws-04,user,user,-,-,-

And sort.awk:

#!/usr/bin/awk -f
# usage: ./sort.awk -v f=FIELD FILE

BEGIN { 
   FS="," 
}

# each line
{ 
   a[NR]=$0 ""
   s[NR]=$f ""  
}

END {
   isort(s,a,NR); 
   for(i=1; i<=NR; i++) print a[i]
}

#insertion sort of A[1..n]
function isort(S, A, n, i, j) {
   for( i=2; i<=n; i++) {
      hs = S[j=i]
      ha = A[j=i]
      while (S[j-1] > hs) { 
         j--; 
         S[j+1] = S[j]
         A[j+1] = A[j] 
      }
      S[j] = hs
      A[j] = ha
   }
}

To use it:

awk sort.awk f=3 < net.csv  # OR 

chmod +x sort.awk
./sort.awk f=3 net.csv

Variably modified array at file scope

The reason for this warning is that const in c doesn't mean constant. It means "read only". So the value is stored at a memory address and could potentially be changed by machine code.

Default values for Vue component props & how to check if a user did not set the prop?

Vue allows for you to specify a default prop value and type directly, by making props an object (see: https://vuejs.org/guide/components.html#Prop-Validation):

props: {
  year: {
    default: 2016,
    type: Number
  }
}

If the wrong type is passed then it throws an error and logs it in the console, here's the fiddle:

https://jsfiddle.net/cexbqe2q/

How to solve Permission denied (publickey) error when using Git?

I had to copy my ssh keys to the root folder. Google Cloud Compute Engine running Ubuntu 18.04

sudo cp ~/.ssh/* /root/.ssh/

C# Break out of foreach loop after X number of items

Or just use a regular for loop instead of foreach. A for loop is slightly faster (though you won't notice the difference except in very time critical code).

What is the default text size on Android?

http://petrnohejl.github.io/Android-Cheatsheet-For-Graphic-Designers/

Text size

Type    Dimension
Micro   12 sp
Small   14 sp
Medium  18 sp
Large   22 sp

Java compiler level does not match the version of the installed Java project facet

TK Gospodinov answer is correct even for maven projects. Beware: I do use Maven. The pom was correct and still got this issue. I went to "Project Facets" and actually removed the Java selection which was pointing to 1.6 but my project is using 1.7. On the right in the "Runtimes" tab I had to check the jdk1.7 option. Nothing appeared on the left even after I hit "Apply". The issue went away though which is why I still think this answer is important of the specific "Project Facets" related issue. After you hit OK if you come back to "Project Facets" you will notice Java shows up as version 1.7 so you can now select it to make sure the project is "marked" as a Java project. I also needed to right click on the project and select Maven|Update Project.

How to sort an STL vector?

A pointer-to-member allows you to write a single comparator, which can work with any data member of your class:

#include <algorithm>
#include <vector>
#include <string>
#include <iostream>

template <typename T, typename U>
struct CompareByMember {
    // This is a pointer-to-member, it represents a member of class T
    // The data member has type U
    U T::*field;
    CompareByMember(U T::*f) : field(f) {}
    bool operator()(const T &lhs, const T &rhs) {
        return lhs.*field < rhs.*field;
    }
};

struct Test {
    int a;
    int b;
    std::string c;
    Test(int a, int b, std::string c) : a(a), b(b), c(c) {}
};

// for convenience, this just lets us print out a Test object
std::ostream &operator<<(std::ostream &o, const Test &t) {
    return o << t.c;
}

int main() {
    std::vector<Test> vec;
    vec.push_back(Test(1, 10, "y"));
    vec.push_back(Test(2, 9, "x"));

    // sort on the string field
    std::sort(vec.begin(), vec.end(), 
        CompareByMember<Test,std::string>(&Test::c));
    std::cout << "sorted by string field, c: ";
    std::cout << vec[0] << " " << vec[1] << "\n";

    // sort on the first integer field
    std::sort(vec.begin(), vec.end(), 
        CompareByMember<Test,int>(&Test::a));
    std::cout << "sorted by integer field, a: ";
    std::cout << vec[0] << " " << vec[1] << "\n";

    // sort on the second integer field
    std::sort(vec.begin(), vec.end(), 
        CompareByMember<Test,int>(&Test::b));
    std::cout << "sorted by integer field, b: ";
    std::cout << vec[0] << " " << vec[1] << "\n";
}

Output:

sorted by string field, c: x y
sorted by integer field, a: y x
sorted by integer field, b: x y

Create a copy of a table within the same database DB2

Two steps works fine:

create table bu_x as (select a,b,c,d from x ) WITH no data;

insert into bu_x (a,b,c,d) select select a,b,c,d from x ;

Local and global temporary tables in SQL Server

Quoting from Books Online:

Local temporary tables are visible only in the current session; global temporary tables are visible to all sessions.

Temporary tables are automatically dropped when they go out of scope, unless explicitly dropped using DROP TABLE:

  • A local temporary table created in a stored procedure is dropped automatically when the stored procedure completes. The table can be referenced by any nested stored procedures executed by the stored procedure that created the table. The table cannot be referenced by the process which called the stored procedure that created the table.
  • All other local temporary tables are dropped automatically at the end of the current session.
  • Global temporary tables are automatically dropped when the session that created the table ends and all other tasks have stopped referencing them. The association between a task and a table is maintained only for the life of a single Transact-SQL statement. This means that a global temporary table is dropped at the completion of the last Transact-SQL statement that was actively referencing the table when the creating session ended.

Order by in Inner Join

Avoid SELECT * in your main query.

Avoid duplicate columns: the JOIN condition ensures One.One_Name and two.One_Name will be equal therefore you don't need to return both in the SELECT clause.

Avoid duplicate column names: rename One.ID and Two.ID using 'aliases'.

Add an ORDER BY clause using the column names ('alises' where applicable) from the SELECT clause.

Suggested re-write:

SELECT T1.ID AS One_ID, T1.One_Name, 
       T2.ID AS Two_ID, T2.Two_name
  FROM One AS T1
       INNER JOIN two AS T2
          ON T1.One_Name = T2.One_Name
 ORDER 
    BY One_ID;

Moment.js transform to date object

moment has updated the js lib as of 06/2018.

var newYork    = moment.tz("2014-06-01 12:00", "America/New_York");
var losAngeles = newYork.clone().tz("America/Los_Angeles");
var london     = newYork.clone().tz("Europe/London");

newYork.format();    // 2014-06-01T12:00:00-04:00
losAngeles.format(); // 2014-06-01T09:00:00-07:00
london.format();     // 2014-06-01T17:00:00+01:00

if you have freedom to use Angular5+, then better use datePipe feature there than the timezone function here. I have to use moment.js because my project limits to Angular2 only.

How can I include null values in a MIN or MAX?

In my expression, count(enddate) counts how many rows where the enddate column is not null. The count(*) expression counts total rows. By comparing, you can easily tell if any value in the enddate column contains null. If they are identical, then max(enddate) is the result. Otherwise the case will default to returning null which is also the answer. This is a very popular way to do this exact check.

SELECT recordid, 
MIN(startdate), 
case when count(enddate) = count(*) then max(enddate) end
FROM tmp 
GROUP BY recordid

How do I connect to a Websphere Datasource with a given JNDI name?

Jason,

This is how it works.

Localnamespace - java:comp/env is a local name space used by the application. The name that you use in it jdbc/db is just an alias. It does not refer to a physical resource.

During deployment this alias should be mapped to a physical resource (in your case a data source) that is defined on the WAS/WPS run time.

This is actually stored in ejb-bnd.xmi files. In the latest versions the XMIs are replaced with XML files. These files are referred to as the Binding files.

HTH Manglu

When should I use UNSIGNED and SIGNED INT in MySQL?

For negative integer value, SIGNED is used and for non-negative integer value, UNSIGNED is used. It always suggested to use UNSIGNED for id as a PRIMARY KEY.

Is there a way to compile node.js source files?

Now this may include more than you need (and may not even work for command line applications in a non-graphical environment, I don't know), but there is nw.js. It's Blink (i.e. Chromium/Webkit) + io.js (i.e. Node.js).

You can use node-webkit-builder to build native executable binaries for Linux, OS X and Windows.

If you want a GUI, that's a huge plus. You can build one with web technologies. If you don't, specify "node-main" in the package.json (and probably "window": {"show": false} although maybe it works to just have a node-main and not a main)

I haven't tried to use it in exactly this way, just throwing it out there as a possibility. I can say it's certainly not an ideal solution for non-graphical Node.js applications.

SQL Server : trigger how to read value for Insert, Update, Delete

Here is the syntax to create a trigger:

CREATE TRIGGER trigger_name
ON { table | view }
[ WITH ENCRYPTION ]
{
    { { FOR | AFTER | INSTEAD OF } { [ INSERT ] [ , ] [ UPDATE ] [ , ] [ DELETE ] }
        [ WITH APPEND ]
        [ NOT FOR REPLICATION ]
        AS
        [ { IF UPDATE ( column )
            [ { AND | OR } UPDATE ( column ) ]
                [ ...n ]
        | IF ( COLUMNS_UPDATED ( ) { bitwise_operator } updated_bitmask )
                { comparison_operator } column_bitmask [ ...n ]
        } ]
        sql_statement [ ...n ]
    }
} 

If you want to use On Update you only can do it with the IF UPDATE ( column ) section. That's not possible to do what you are asking.

Parse DateTime string in JavaScript

We use this code to check if the string is a valid date

var dt = new Date(txtDate.value)
if (isNaN(dt))

Best way to clear a PHP array's values

Like Zack said in the comments below you are able to simply re-instantiate it using

$foo = array(); // $foo is still here

If you want something more powerful use unset since it also will clear $foo from the symbol table, if you need the array later on just instantiate it again.

unset($foo); // $foo is gone
$foo = array(); // $foo is here again

How to form a correct MySQL connection string?

string MyConString = "Data Source='mysql7.000webhost.com';" +
"Port=3306;" +
"Database='a455555_test';" +
"UID='a455555_me';" +
"PWD='something';";

Seaborn plots not showing up

Plots created using seaborn need to be displayed like ordinary matplotlib plots. This can be done using the

plt.show()

function from matplotlib.

Originally I posted the solution to use the already imported matplotlib object from seaborn (sns.plt.show()) however this is considered to be a bad practice. Therefore, simply directly import the matplotlib.pyplot module and show your plots with

import matplotlib.pyplot as plt
plt.show()

If the IPython notebook is used the inline backend can be invoked to remove the necessity of calling show after each plot. The respective magic is

%matplotlib inline

Save byte array to file

You can use:

File.WriteAllBytes("Foo.txt", arrBytes); // Requires System.IO

If you have an enumerable and not an array, you can use:

File.WriteAllBytes("Foo.txt", arrBytes.ToArray()); // Requires System.Linq

Run Command Line & Command From VBS

Set oShell = CreateObject ("WScript.Shell") 
oShell.run "cmd.exe /C copy ""S:Claims\Sound.wav"" ""C:\WINDOWS\Media\Sound.wav"" "

get everything between <tag> and </tag> with php

this function worked for me

<?php

function everything_in_tags($string, $tagname)
{
    $pattern = "#<\s*?$tagname\b[^>]*>(.*?)</$tagname\b[^>]*>#s";
    preg_match($pattern, $string, $matches);
    return $matches[1];
}

?>

The program can't start because MSVCR110.dll is missing from your computer

I was getting a similar issue from the Apache Lounge 32 bit version. After downloading the 64 bit version, the issue was resolved.

Here is an excellent video explain the steps involved: https://www.youtube.com/watch?v=17qhikHv5hY

Express.js - app.listen vs server.listen

I came with same question but after google, I found there is no big difference :)

From Github

If you wish to create both an HTTP and HTTPS server you may do so with the "http" and "https" modules as shown here.

/**
 * Listen for connections.
 *
 * A node `http.Server` is returned, with this
 * application (which is a `Function`) as its
 * callback. If you wish to create both an HTTP
 * and HTTPS server you may do so with the "http"
 * and "https" modules as shown here:
 *
 *    var http = require('http')
 *      , https = require('https')
 *      , express = require('express')
 *      , app = express();
 *
 *    http.createServer(app).listen(80);
 *    https.createServer({ ... }, app).listen(443);
 *
 * @return {http.Server}
 * @api public
 */

app.listen = function(){
  var server = http.createServer(this);
  return server.listen.apply(server, arguments);
};

Also if you want to work with socket.io see their example

See this

I prefer app.listen() :)

Is there a simple way to convert C++ enum to string?

You could use a reflection library, like Ponder. You register the enums and then you can convert them back and forth with the API.

enum class MyEnum
{
    Zero = 0,
    One  = 1,
    Two  = 2
};

ponder::Enum::declare<MyEnum>()
    .value("Zero", MyEnum::Zero)
    .value("One",  MyEnum::One)
    .value("Two",  MyEnum::Two);

ponder::EnumObject zero(MyEnum::Zero);

zero.name(); // -> "Zero"

From Arraylist to Array

ArrayList<String> a = new ArrayList<String>();
a.add( "test" );
@SuppressWarnings( "unused")
Object[] array = a.toArray();

It depends on what you want to achieve if you need to manipulate the array later it would cost more effort than keeping the string in the ArrayList. You have also random access with an ArrayList by list.get( index );

DevTools failed to load SourceMap: Could not load content for chrome-extension

For me, the problem was caused not by the app in development itself but by the Chrome extension: React Developer Tool. I solved partially that by right-clicking the extension icon in the toolbar, clicking "manage extension" (I'm freely translating menu text here since my browser language is in Brazilian Portuguese), then enabling "Allow access to files URLs." But this measure fixed just some of the alerts.

I found issues in the react repo that suggests the cause is a bug in their extension and is planned to be corrected soon - see issues 20091 and 20075.

You can confirm is extension-related by accessing your app in an anonymous tab without any extension enabled.

Python, how to read bytes from file and save it?

Use the open function to open the file. The open function returns a file object, which you can use the read and write to files:

file_input = open('input.txt') #opens a file in reading mode
file_output = open('output.txt') #opens a file in writing mode

data = file_input.read(1024) #read 1024 bytes from the input file
file_output.write(data) #write the data to the output file

How to get Javascript Select box's selected text

Please try this code:

$("#YourSelect>option:selected").html()

How to skip to next iteration in jQuery.each() util?

What they mean by non-false is:

return true;

So this code:

_x000D_
_x000D_
var arr = ["one", "two", "three", "four", "five"];_x000D_
$.each(arr, function(i) {_x000D_
  if (arr[i] == 'three') {_x000D_
    return true;_x000D_
  }_x000D_
  console.log(arr[i]);_x000D_
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

will log one, two, four, five.

Position DIV relative to another DIV?

First set position of the parent DIV to relative (specifying the offset, i.e. left, top etc. is not necessary) and then apply position: absolute to the child DIV with the offset you want.
It's simple and should do the trick well.

What is the difference between localStorage, sessionStorage, session and cookies?

OK, LocalStorage as it's called it's local storage for your browsers, it can save up to 10MB, SessionStorage does the same, but as it's name saying, it's session based and will be deleted after closing your browser, also can save less than LocalStorage, like up to 5MB, but Cookies are very tiny data storing in your browser, that can save up 4KB and can be accessed through server or browser both...

I also created the image below to show the differences at a glance:

LocalStorage, SessionStorage and Cookies

How to enable file sharing for my app?

You just have to set UIFileSharingEnabled (Application Supports iTunes file sharing) key in the info plist of your app. Here's a link for the documentation. Scroll down to the file sharing support part.

In the past, it was also necessary to define CFBundleDisplayName (Bundle Display Name), if it wasn't already there. More details here.

Python read JSON file and modify

I would like to present a modified version of Vadim's solution. It helps to deal with asynchronous requests to write/modify json file. I know it wasn't a part of the original question but might be helpful for others.

In case of asynchronous file modification os.remove(filename) will raise FileNotFoundError if requests emerge frequently. To overcome this problem you can create temporary file with modified content and then rename it simultaneously replacing old version. This solution works fine both for synchronous and asynchronous cases.

import os, json, uuid

filename = 'data.json'
with open(filename, 'r') as f:
    data = json.load(f)
    data['id'] = 134 # <--- add `id` value.
    # add, remove, modify content

# create randomly named temporary file to avoid 
# interference with other thread/asynchronous request
tempfile = os.path.join(os.path.dirname(filename), str(uuid.uuid4()))
with open(tempfile, 'w') as f:
    json.dump(data, f, indent=4)

# rename temporary file replacing old file
os.rename(tempfile, filename)

CSS table td width - fixed, not flexible

It is not only the table cell which is growing, the table itself can grow, too. To avoid this you can assign a fixed width to the table which in return forces the cell width to be respected:

table {
  table-layout: fixed;
  width: 120px; /* Important */
}
td {
  width: 30px;
}

(Using overflow: hidden and/or text-overflow: ellipsis is optional but highly recommended for a better visual experience)

So if your situation allows you to assign a fixed width to your table, this solution might be a better alternative to the other given answers (which do work with or without a fixed width)

Spring Boot application in eclipse, the Tomcat connector configured to listen on port XXXX failed to start

if it's convenient for you, and you don't want to use the command line, you can reboot your computer, it helps!

How do I get the unix timestamp in C as an int?

With second precision, you can print tv_sec field of timeval structure that you get from gettimeofday() function. For example:

#include <sys/time.h>
#include <stdio.h>

int main()
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    printf("Seconds since Jan. 1, 1970: %ld\n", tv.tv_sec);
    return 0;
}

Example of compiling and running:

$ gcc -Wall -o test ./test.c 
$ ./test 
Seconds since Jan. 1, 1970: 1343845834

Note, however, that its been a while since epoch and so long int is used to fit a number of seconds these days.

There are also functions to print human-readable times. See this manual page for details. Here goes an example using ctime():

#include <time.h>
#include <stdio.h>

int main()
{
    time_t clk = time(NULL);
    printf("%s", ctime(&clk));
    return 0;
}

Example run & output:

$ gcc -Wall -o test ./test.c 
$ ./test 
Wed Aug  1 14:43:23 2012
$ 

Mocking static methods with Mockito

For those who use JUnit 5, Powermock is not an option. You'll require the following dependencies to successfully mock a static method with just Mockito.

testCompile    group: 'org.mockito', name: 'mockito-core',           version: '3.6.0'
testCompile    group: 'org.mockito', name: 'mockito-junit-jupiter',  version: '3.6.0'
testCompile    group: 'org.mockito', name: 'mockito-inline',         version: '3.6.0'

mockito-junit-jupiter add supports for JUnit 5.

And support for mocking static methods is provided by mockito-inline dependency.

Example:

@Test
void returnUtilTest() {
    assertEquals("foo", UtilClass.staticMethod("foo"));

    try (MockedStatic<UtilClass> classMock = mockStatic(UtilClass.class)) {

        classMock.when(() -> UtilClass.staticMethod("foo")).thenReturn("bar");

        assertEquals("bar", UtilClass.staticMethod("foo"));
     }

     assertEquals("foo", UtilClass.staticMethod("foo"));
}

The try-with-resource block is used to make the static mock remains temporary, so it's mocked only within that scope.

When not using a try block, make sure to close the scoped mock, once you are done with the assertions.

MockedStatic<UtilClass> classMock = mockStatic(UtilClass.class)
classMock.when(() -> UtilClass.staticMethod("foo")).thenReturn("bar");
assertEquals("bar", UtilClass.staticMethod("foo"));
classMock.close();

Mocking void methods:

When mockStatic is called on a class, all the static void methods in that class automatically get mocked to doNothing().

Entity Framework: table without primary key

In EF Core 5.0, you will be able to define it at entity level also.

[Keyless]
public class Address
{
    public string Street { get; set; }
    public string City { get; set; }
    public int Zip { get; set; }
}

Reference: https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-5.0/whatsnew#use-a-c-attribute-to-indicate-that-an-entity-has-no-key

Why doesn't Python have a sign function?

EDIT:

Indeed there was a patch which included sign() in math, but it wasn't accepted, because they didn't agree on what it should return in all the edge cases (+/-0, +/-nan, etc)

So they decided to implement only copysign, which (although more verbose) can be used to delegate to the end user the desired behavior for edge cases - which sometimes might require the call to cmp(x,0).


I don't know why it's not a built-in, but I have some thoughts.

copysign(x,y):
Return x with the sign of y.

Most importantly, copysign is a superset of sign! Calling copysign with x=1 is the same as a sign function. So you could just use copysign and forget about it.

>>> math.copysign(1, -4)
-1.0
>>> math.copysign(1, 3)
1.0

If you get sick of passing two whole arguments, you can implement sign this way, and it will still be compatible with the IEEE stuff mentioned by others:

>>> sign = functools.partial(math.copysign, 1) # either of these
>>> sign = lambda x: math.copysign(1, x) # two will work
>>> sign(-4)
-1.0
>>> sign(3)
1.0
>>> sign(0)
1.0
>>> sign(-0.0)
-1.0
>>> sign(float('nan'))
-1.0

Secondly, usually when you want the sign of something, you just end up multiplying it with another value. And of course that's basically what copysign does.

So, instead of:

s = sign(a)
b = b * s

You can just do:

b = copysign(b, a)

And yes, I'm surprised you've been using Python for 7 years and think cmp could be so easily removed and replaced by sign! Have you never implemented a class with a __cmp__ method? Have you never called cmp and specified a custom comparator function?

In summary, I've found myself wanting a sign function too, but copysign with the first argument being 1 will work just fine. I disagree that sign would be more useful than copysign, as I've shown that it's merely a subset of the same functionality.

What does <value optimized out> mean in gdb?

Minimal runnable example with disassembly analysis

As usual, I like to see some disassembly to get a better understanding of what is going on.

In this case, the insight we obtain is that if a variable is optimized to be stored only in a register rather than the stack, and then the register it was in gets overwritten, then it shows as <optimized out> as mentioned by R..

Of course, this can only happen if the variable in question is not needed anymore, otherwise the program would lose its value. Therefore it tends to happen that at the start of the function you can see the variable value, but then at the end it becomes <optimized out>.

One typical case which we often are interested in of this is that of the function arguments themselves, since these are:

  • always defined at the start of the function
  • may not get used towards the end of the function as more intermediate values are calculated.
  • tend to get overwritten by further function subcalls which must setup the exact same registers to satisfy the calling convention

This understanding actually has a concrete application: when using reverse debugging, you might be able to recover the value of variables of interest simply by stepping back to their last point of usage: How do I view the value of an <optimized out> variable in C++?

main.c

#include <stdio.h>

int __attribute__((noinline)) f3(int i) {
    return i + 1;
}

int __attribute__((noinline)) f2(int i) {
    return f3(i) + 1;
}

int __attribute__((noinline)) f1(int i) {
    int j = 1, k = 2, l = 3;
    i += 1;
    j += f2(i);
    k += f2(j);
    l += f2(k);
    return l;
}

int main(int argc, char *argv[]) {
    printf("%d\n", f1(argc));
    return 0;
}

Compile and run:

gcc -ggdb3 -O3 -std=c99 -Wall -Wextra -pedantic -o main.out main.c
gdb -q -nh main.out

Then inside GDB, we have the following session:

Breakpoint 1, f1 (i=1) at main.c:13
13          i += 1;
(gdb) disas
Dump of assembler code for function f1:
=> 0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$1 = 1
(gdb) p j
$2 = 1
(gdb) n
14          j += f2(i);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
=> 0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$3 = 2
(gdb) p j
$4 = 1
(gdb) n
15          k += f2(j);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
=> 0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
   0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$5 = <optimized out>
(gdb) p j
$6 = 5
(gdb) n
16          l += f2(k);
(gdb) disas
Dump of assembler code for function f1:
   0x00005555555546c0 <+0>:     add    $0x1,%edi
   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi
   0x00005555555546cb <+11>:    callq  0x5555555546b0 <f2>
   0x00005555555546d0 <+16>:    lea    0x2(%rax),%edi
=> 0x00005555555546d3 <+19>:    callq  0x5555555546b0 <f2>
   0x00005555555546d8 <+24>:    add    $0x3,%eax
   0x00005555555546db <+27>:    retq   
End of assembler dump.
(gdb) p i
$7 = <optimized out>
(gdb) p j
$8 = <optimized out>

To understand what is going on, remember from the x86 Linux calling convention: What are the calling conventions for UNIX & Linux system calls on i386 and x86-64 you should know that:

  • RDI contains the first argument
  • RDI can get destroyed in function calls
  • RAX contains the return value

From this we deduce that:

add    $0x1,%edi

corresponds to the:

i += 1;

since i is the first argument of f1, and therefore stored in RDI.

Now, while we were at both:

i += 1;
j += f2(i);

the value of RDI hadn't been modified, and therefore GDB could just query it at anytime in those lines.

However, as soon as the f2 call is made:

  • the value of i is not needed anymore in the program
  • lea 0x1(%rax),%edi does EDI = j + RAX + 1, which both:
    • initializes j = 1
    • sets up the first argument of the next f2 call to RDI = j

Therefore, when the following line is reached:

k += f2(j);

both of the following instructions have/may have modified RDI, which is the only place i was being stored (f2 may use it as a scratch register, and lea definitely set it to RAX + 1):

   0x00005555555546c3 <+3>:     callq  0x5555555546b0 <f2>
   0x00005555555546c8 <+8>:     lea    0x1(%rax),%edi

and so RDI does not contain the value of i anymore. In fact, the value of i was completely lost! Therefore the only possible outcome is:

$3 = <optimized out>

A similar thing happens to the value of j, although j only becomes unnecessary one line later afer the call to k += f2(j);.

Thinking about j also gives us some insight on how smart GDB is. Notably, at i += 1;, the value of j had not yet materialized in any register or memory address, and GDB must have known it based solely on debug information metadata.

-O0 analysis

If we use -O0 instead of -O3 for compilation:

gcc -ggdb3 -O0 -std=c99 -Wall -Wextra -pedantic -o main.out main.c

then the disassembly would look like:

11      int __attribute__((noinline)) f1(int i) {
=> 0x0000555555554673 <+0>:     55      push   %rbp
   0x0000555555554674 <+1>:     48 89 e5        mov    %rsp,%rbp
   0x0000555555554677 <+4>:     48 83 ec 18     sub    $0x18,%rsp
   0x000055555555467b <+8>:     89 7d ec        mov    %edi,-0x14(%rbp)

12          int j = 1, k = 2, l = 3;
   0x000055555555467e <+11>:    c7 45 f4 01 00 00 00    movl   $0x1,-0xc(%rbp)
   0x0000555555554685 <+18>:    c7 45 f8 02 00 00 00    movl   $0x2,-0x8(%rbp)
   0x000055555555468c <+25>:    c7 45 fc 03 00 00 00    movl   $0x3,-0x4(%rbp)

13          i += 1;
   0x0000555555554693 <+32>:    83 45 ec 01     addl   $0x1,-0x14(%rbp)

14          j += f2(i);
   0x0000555555554697 <+36>:    8b 45 ec        mov    -0x14(%rbp),%eax
   0x000055555555469a <+39>:    89 c7   mov    %eax,%edi
   0x000055555555469c <+41>:    e8 b8 ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546a1 <+46>:    01 45 f4        add    %eax,-0xc(%rbp)

15          k += f2(j);
   0x00005555555546a4 <+49>:    8b 45 f4        mov    -0xc(%rbp),%eax
   0x00005555555546a7 <+52>:    89 c7   mov    %eax,%edi
   0x00005555555546a9 <+54>:    e8 ab ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546ae <+59>:    01 45 f8        add    %eax,-0x8(%rbp)

16          l += f2(k);
   0x00005555555546b1 <+62>:    8b 45 f8        mov    -0x8(%rbp),%eax
   0x00005555555546b4 <+65>:    89 c7   mov    %eax,%edi
   0x00005555555546b6 <+67>:    e8 9e ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546bb <+72>:    01 45 fc        add    %eax,-0x4(%rbp)

17          return l;
   0x00005555555546be <+75>:    8b 45 fc        mov    -0x4(%rbp),%eax

18      }
   0x00005555555546c1 <+78>:    c9      leaveq 
   0x00005555555546c2 <+79>:    c3      retq 

From this horrendous disassembly, we see that the value of RDI is moved to the stack at the very start of program execution at:

mov    %edi,-0x14(%rbp)

and it then gets retrieved from memory into registers whenever needed, e.g. at:

14          j += f2(i);
   0x0000555555554697 <+36>:    8b 45 ec        mov    -0x14(%rbp),%eax
   0x000055555555469a <+39>:    89 c7   mov    %eax,%edi
   0x000055555555469c <+41>:    e8 b8 ff ff ff  callq  0x555555554659 <f2>
   0x00005555555546a1 <+46>:    01 45 f4        add    %eax,-0xc(%rbp)

The same basically happens to j which gets immediately pushed to the stack when when it is initialized:

   0x000055555555467e <+11>:    c7 45 f4 01 00 00 00    movl   $0x1,-0xc(%rbp)

Therefore, it is easy for GDB to find the values of those variables at any time: they are always present in memory!

This also gives us some insight on why it is not possible to avoid <optimized out> in optimized code: since the number of registers is limited, the only way to do that would be to actually push unneeded registers to memory, which would partly defeat the benefit of -O3.

Extend the lifetime of i

If we edited f1 to return l + i as in:

int __attribute__((noinline)) f1(int i) {
    int j = 1, k = 2, l = 3;
    i += 1;
    j += f2(i);
    k += f2(j);
    l += f2(k);
    return l + i;
}

then we observe that this effectively extends the visibility of i until the end of the function.

This is because with this we force GCC to use an extra variable to keep i around until the end:

   0x00005555555546c0 <+0>:     lea    0x1(%rdi),%edx
   0x00005555555546c3 <+3>:     mov    %edx,%edi
   0x00005555555546c5 <+5>:     callq  0x5555555546b0 <f2>
   0x00005555555546ca <+10>:    lea    0x1(%rax),%edi
   0x00005555555546cd <+13>:    callq  0x5555555546b0 <f2>
   0x00005555555546d2 <+18>:    lea    0x2(%rax),%edi
   0x00005555555546d5 <+21>:    callq  0x5555555546b0 <f2>
   0x00005555555546da <+26>:    lea    0x3(%rdx,%rax,1),%eax
   0x00005555555546de <+30>:    retq

which the compiler does by storing i += i in RDX at the very first instruction.

Tested in Ubuntu 18.04, GCC 7.4.0, GDB 8.1.0.

CSS Equivalent of the "if" statement

There is no native IF/ELSE for CSS available. CSS preprocessors like SASS (and Compass) can help, but if you’re looking for more feature-specific if/else conditions you should give Modernizr a try. It does feature-detection and then adds classes to the HTML element to indicate which CSS3 & HTML5 features the browser supports and doesn’t support. You can then write very if/else-like CSS right in your CSS without any preprocessing, like this:

.geolocation #someElem {
   /* only apply this if the browser supports Geolocation */
}
.no-geolocation #someElem {
   /* only apply this if the browser DOES NOT support Geolocation */
}

Keep in mind that you should always progressively enhance, so rather than the above example (which illustrates the point better), you should write something more like this:

#someElem {
   /* default styles, suitable for both Geolocation support and lack thereof */
}
.geolocation #someElem {
   /* only properties as needed to overwrite the default styling  */
}

Note that Modernizr does rely on JavaScript, so if JS is disabled you wouldn’t get anything. Hence the progressive enhancement approach of #someElem first, as a no-js foundation.

How to draw vertical lines on a given plot in matplotlib

The standard way to add vertical lines that will cover your entire plot window without you having to specify their actual height is plt.axvline

import matplotlib.pyplot as plt

plt.axvline(x=0.22058956)
plt.axvline(x=0.33088437)
plt.axvline(x=2.20589566)

OR

xcoords = [0.22058956, 0.33088437, 2.20589566]
for xc in xcoords:
    plt.axvline(x=xc)

You can use many of the keywords available for other plot commands (e.g. color, linestyle, linewidth ...). You can pass in keyword arguments ymin and ymax if you like in axes corrdinates (e.g. ymin=0.25, ymax=0.75 will cover the middle half of the plot). There are corresponding functions for horizontal lines (axhline) and rectangles (axvspan).

How to vertical align an inline-block in a line of text?

display: inline-block is your friend you just need all three parts of the construct - before, the "block", after - to be one, then you can vertically align them all to the middle:

Working Example

(it looks like your picture anyway ;))

CSS:

p, div {
  display: inline-block; 
  vertical-align: middle;
}
p, div {
  display: inline !ie7; /* hack for IE7 and below */
}

table {
  background: #000; 
  color: #fff; 
  font-size: 16px; 
  font-weight: bold; margin: 0 10px;
}

td {
  padding: 5px; 
  text-align: center;
}

HTML:

<p>some text</p> 
<div>
  <table summary="">
  <tr><td>A</td></tr>
  <tr><td>B</td></tr>
  <tr><td>C</td></tr>
  <tr><td>D</td></tr>
  </table>
</div> 
<p>continues afterwards</p>

Scanning Java annotations at runtime

The Classloader API doesn't have an "enumerate" method, because class loading is an "on-demand" activity -- you usually have thousands of classes in your classpath, only a fraction of which will ever be needed (the rt.jar alone is 48MB nowadays!).

So, even if you could enumerate all classes, this would be very time- and memory-consuming.

The simple approach is to list the concerned classes in a setup file (xml or whatever suits your fancy); if you want to do this automatically, restrict yourself to one JAR or one class directory.

Combining INSERT INTO and WITH/CTE

The WITH clause for Common Table Expressions go at the top.

Wrapping every insert in a CTE has the benefit of visually segregating the query logic from the column mapping.

Spot the mistake:

WITH _INSERT_ AS (
  SELECT
    [BatchID]      = blah
   ,[APartyNo]     = blahblah
   ,[SourceRowID]  = blahblahblah
  FROM Table1 AS t1
)
INSERT Table2
      ([BatchID], [SourceRowID], [APartyNo])
SELECT [BatchID], [APartyNo], [SourceRowID]   
FROM _INSERT_

Same mistake:

INSERT Table2 (
  [BatchID]
 ,[SourceRowID]
 ,[APartyNo]
)
SELECT
  [BatchID]      = blah
 ,[APartyNo]     = blahblah
 ,[SourceRowID]  = blahblahblah
FROM Table1 AS t1

A few lines of boilerplate make it extremely easy to verify the code inserts the right number of columns in the right order, even with a very large number of columns. Your future self will thank you later.

Hiding axis text in matplotlib plots

I was not actually able to render an image without borders or axis data based on any of the code snippets here (even the one accepted at the answer). After digging through some API documentation, I landed on this code to render my image

plt.axis('off')
plt.tick_params(axis='both', left='off', top='off', right='off', bottom='off', labelleft='off', labeltop='off', labelright='off', labelbottom='off')
plt.savefig('foo.png', dpi=100, bbox_inches='tight', pad_inches=0.0)

I used the tick_params call to basically shut down any extra information that might be rendered and I have a perfect graph in my output file.

How can I center a div within another div?

It is because your width is set to auto. You have to specify the width for it to be visibly centered.

Your #container spans the whole width of the #main_content. That's why it seems not centered.

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

JSONObject obj=(JSONObject)JSONValue.parse(content); 
JSONArray arr=(JSONArray)obj.get("units"); 
System.out.println(arr.get(1));  //this will print {"id":42,...sities ..}

@cyberz is right but explain it reverse

What is the main difference between Collection and Collections in Java?

Collection, as its javadoc says is "The root interface in the collection hierarchy." This means that every single class implementing Collection in any form is part of the Java Collections Framework.

The Collections Framework is Java's native implementation of data structure classes (with implementation specific properties) which represent a group of objects which are somehow related to each other and thus can be called a collection.

Collections is merely an utility method class for doing certain operations, for example adding thread safety to your ArrayList instance by doing this:

List<MyObj> list = Collections.synchronizedList(new Arraylist<MyObj>());

The main difference in my opinion is that Collection is base interface which you may use in your code as a type for object (although I wouldn't directly recommend that) while Collections just provides useful operations for handling the collections.

convert string to number node.js

Using parseInt() is a bad idea mainly because it never fails. Also because some results can be unexpected, like in the case of INFINITY.
Below is the function for handling unexpected behaviour.

function cleanInt(x) {
    x = Number(x);
    return x >= 0 ? Math.floor(x) : Math.ceil(x);
}

See results of below test cases.

console.log("CleanInt: ", cleanInt('xyz'), " ParseInt: ", parseInt('xyz'));
console.log("CleanInt: ", cleanInt('123abc'), " ParseInt: ", parseInt('123abc'));
console.log("CleanInt: ", cleanInt('234'), " ParseInt: ", parseInt('234'));
console.log("CleanInt: ", cleanInt('-679'), " ParseInt: ", parseInt('-679'));
console.log("CleanInt: ", cleanInt('897.0998'), " ParseInt: ", parseInt('897.0998'));
console.log("CleanInt: ", cleanInt('Infinity'), " ParseInt: ", parseInt('Infinity'));

result:

CleanInt:  NaN  ParseInt:  NaN
CleanInt:  NaN  ParseInt:  123
CleanInt:  234  ParseInt:  234
CleanInt:  -679  ParseInt:  -679
CleanInt:  897  ParseInt:  897
CleanInt:  Infinity  ParseInt:  NaN

How to restore the menu bar in Visual Studio Code

press Alt to seee the Menubar and then go to view - appearance and remove the check from the fullscreen option

Correct format specifier for double in printf

Given the C99 standard (namely, the N1256 draft), the rules depend on the function kind: fprintf (printf, sprintf, ...) or scanf.

Here are relevant parts extracted:

Foreword

This second edition cancels and replaces the first edition, ISO/IEC 9899:1990, as amended and corrected by ISO/IEC 9899/COR1:1994, ISO/IEC 9899/AMD1:1995, and ISO/IEC 9899/COR2:1996. Major changes from the previous edition include:

  • %lf conversion specifier allowed in printf

7.19.6.1 The fprintf function

7 The length modifiers and their meanings are:

l (ell) Specifies that (...) has no effect on a following a, A, e, E, f, F, g, or G conversion specifier.

L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier applies to a long double argument.

The same rules specified for fprintf apply for printf, sprintf and similar functions.

7.19.6.2 The fscanf function

11 The length modifiers and their meanings are:

l (ell) Specifies that (...) that a following a, A, e, E, f, F, g, or G conversion specifier applies to an argument with type pointer to double;

L Specifies that a following a, A, e, E, f, F, g, or G conversion specifier applies to an argument with type pointer to long double.

12 The conversion specifiers and their meanings are: a,e,f,g Matches an optionally signed floating-point number, (...)

14 The conversion specifiers A, E, F, G, and X are also valid and behave the same as, respectively, a, e, f, g, and x.

The long story short, for fprintf the following specifiers and corresponding types are specified:

  • %f -> double
  • %Lf -> long double.

and for fscanf it is:

  • %f -> float
  • %lf -> double
  • %Lf -> long double.

event.preventDefault() function not working in IE

in IE, you can use

event.returnValue = false;

to achieve the same result.

And in order not to get an error, you can test for the existence of preventDefault:

if(event.preventDefault) event.preventDefault();

You can combine the two with:

event.preventDefault ? event.preventDefault() : (event.returnValue = false);

C++ - how to find the length of an integer

How about (works also for 0 and negatives):

int digits( int x ) { 
    return ( (bool) x * (int) log10( abs( x ) ) + 1 );
}

Get name of object or class

All we need:

  1. Wrap a constant in a function (where the name of the function equals the name of the object we want to get)
  2. Use arrow functions inside the object

_x000D_
_x000D_
console.clear();_x000D_
function App(){ // name of my constant is App_x000D_
  return {_x000D_
  a: {_x000D_
    b: {_x000D_
      c: ()=>{ // very important here, use arrow function _x000D_
        console.log(this.constructor.name)_x000D_
      }_x000D_
    }_x000D_
  }_x000D_
}_x000D_
}_x000D_
const obj = new App(); // usage_x000D_
_x000D_
obj.a.b.c(); // App_x000D_
_x000D_
// usage with react props etc, _x000D_
// For instance, we want to pass this callback to some component_x000D_
_x000D_
const myComponent = {};_x000D_
myComponent.customProps = obj.a.b.c;_x000D_
myComponent.customProps(); // App
_x000D_
_x000D_
_x000D_

JQuery create new select option

How about

$('#county').append(
    $('<option />')
        .text('Select a city / town in Sweden')
        .val(''),
    $('<option />')
        .text('Melbourne')
        .val('Melbourne')
);

iPad WebApp Full Screen in Safari

This only works after you save a bookmark to the app to the home screen. Not if you just browse to the site normally.

Open Form2 from Form1, close Form1 from Form2

I did this once for my project, to close one application and open another application.

    System.Threading.Thread newThread;
    Form1 frmNewForm = new Form1;

   newThread = new System.Threading.Thread(new System.Threading.ThreadStart(frmNewFormThread));
this.Close();
        newThread.SetApartmentState(System.Threading.ApartmentState.STA);
        newThread.Start();

And add the following Method. Your newThread.Start will call this method.

    public void frmNewFormThread)()
    {

        Application.Run(frmNewForm);

    }

Change onClick attribute with javascript

You want to do this - set a function that will be executed to respond to the onclick event:

document.getElementById('buttonLED'+id).onclick = function(){ writeLED(1,1); } ;

The things you are doing don't work because:

  1. The onclick event handler expects to have a function, here you are assigning a string

    document.getElementById('buttonLED'+id).onclick = "writeLED(1,1)";
    
  2. In this, you are assigning as the onclick event handler the result of executing the writeLED(1,1) function:

    document.getElementById('buttonLED'+id).onclick = writeLED(1,1);
    

Android Studio - Device is connected but 'offline'

Disabling and Enabling the Developer options and debug mode on the Android phone settings fixed the issue.

How to make a char string from a C macro's value?

#include <stdio.h>

#define QUOTEME(x) #x

#ifndef TEST_FUN
#  define TEST_FUN func_name
#  define TEST_FUN_NAME QUOTEME(TEST_FUN)
#endif

int main(void)
{
    puts(TEST_FUN_NAME);
    return 0;
}

Reference: Wikipedia's C preprocessor page

Cannot connect to MySQL 4.1+ using old authentication

On OSX, I used MacPorts to address the same problem when connecting to my siteground database. Siteground appears to be using 5.0.77mm0.1-log, but creating a new user account didn't fix the problem. This is what did

sudo port install php5-mysql -mysqlnd +mysql5

This downgrades the mysql driver that php will use.

How can I get a vertical scrollbar in my ListBox?

I was having the same problem, I had a ComboBox followed by a ListBox in a StackPanel and the scroll bar for the ListBox was not showing up. I solved this by putting the two in a DockPanel instead. I set the ComboBox DockPanel.Dock="Top" and let the ListBox fill the remaining space.

Cron and virtualenv

Rather than mucking around with virtualenv-specific shebangs, just prepend PATH onto the crontab.

From an activated virtualenv, run these three commands and python scripts should just work:

$ echo "PATH=$PATH" > myserver.cron
$ crontab -l >> myserver.cron
$ crontab myserver.cron

The crontab's first line should now look like this:

PATH=/home/me/virtualenv/bin:/usr/bin:/bin:  # [etc...]

Disable same origin policy in Chrome

For Windows:

(using windows 8.1, chrome 44.0)

First, close google chrome.

Then, open command prompt and go to the folder where 'chrome.exe' is.

( for me: 'chrome.exe' is here "C:\Program Files (x86)\Google\Chrome\Application".

So I type: cd C:\Program Files (x86)\Google\Chrome\Application )

now type: chrome.exe --disable-web-security

a new window of chrome will open.

Rotate a div using javascript

I recently had to build something similar. You can check it out in the snippet below.

The version I had to build uses the same button to start and stop the spinner, but you can manipulate to code if you have a button to start the spin and a different button to stop the spin

Basically, my code looks like this...

Run Code Snippet

_x000D_
_x000D_
var rocket = document.querySelector('.rocket');_x000D_
var btn = document.querySelector('.toggle');_x000D_
var rotate = false;_x000D_
var runner;_x000D_
var degrees = 0;_x000D_
_x000D_
function start(){_x000D_
    runner = setInterval(function(){_x000D_
        degrees++;_x000D_
        rocket.style.webkitTransform = 'rotate(' + degrees + 'deg)';_x000D_
    },50)_x000D_
}_x000D_
_x000D_
function stop(){_x000D_
    clearInterval(runner);_x000D_
}_x000D_
_x000D_
btn.addEventListener('click', function(){_x000D_
    if (!rotate){_x000D_
        rotate = true;_x000D_
        start();_x000D_
    } else {_x000D_
        rotate = false;_x000D_
        stop();_x000D_
    }_x000D_
})
_x000D_
body {_x000D_
  background: #1e1e1e;_x000D_
}    _x000D_
_x000D_
.rocket {_x000D_
    width: 150px;_x000D_
    height: 150px;_x000D_
    margin: 1em;_x000D_
    border: 3px dashed teal;_x000D_
    border-radius: 50%;_x000D_
    background-color: rgba(128,128,128,0.5);_x000D_
    display: flex;_x000D_
    justify-content: center;_x000D_
    align-items: center;_x000D_
  }_x000D_
  _x000D_
  .rocket h1 {_x000D_
    margin: 0;_x000D_
    padding: 0;_x000D_
    font-size: .8em;_x000D_
    color: skyblue;_x000D_
    letter-spacing: 1em;_x000D_
    text-shadow: 0 0 10px black;_x000D_
  }_x000D_
  _x000D_
  .toggle {_x000D_
    margin: 10px;_x000D_
    background: #000;_x000D_
    color: white;_x000D_
    font-size: 1em;_x000D_
    padding: .3em;_x000D_
    border: 2px solid red;_x000D_
    outline: none;_x000D_
    letter-spacing: 3px;_x000D_
  }
_x000D_
<div class="rocket"><h1>SPIN ME</h1></div>_x000D_
<button class="toggle">I/0</button>
_x000D_
_x000D_
_x000D_

Alternative to mysql_real_escape_string without connecting to DB

In direct opposition to my other answer, this following function is probably safe, even with multi-byte characters.

// replace any non-ascii character with its hex code.
function escape($value) {
    $return = '';
    for($i = 0; $i < strlen($value); ++$i) {
        $char = $value[$i];
        $ord = ord($char);
        if($char !== "'" && $char !== "\"" && $char !== '\\' && $ord >= 32 && $ord <= 126)
            $return .= $char;
        else
            $return .= '\\x' . dechex($ord);
    }
    return $return;
}

I'm hoping someone more knowledgeable than myself can tell me why the code above won't work ...

How to make a simple rounded button in Storyboard?

Follow the screenshot below. It works when you run the simulator (won't see it on preview)

Adding UIView rounded border

Gson: Directly convert String to JsonObject (no POJO)

Came across a scenario with remote sorting of data store in EXTJS 4.X where the string is sent to the server as a JSON array (of only 1 object).
Similar approach to what is presented previously for a simple string, just need conversion to JsonArray first prior to JsonObject.

String from client: [{"property":"COLUMN_NAME","direction":"ASC"}]

String jsonIn = "[{\"property\":\"COLUMN_NAME\",\"direction\":\"ASC\"}]";
JsonArray o = (JsonArray)new JsonParser().parse(jsonIn);

String sortColumn = o.get(0).getAsJsonObject().get("property").getAsString());
String sortDirection = o.get(0).getAsJsonObject().get("direction").getAsString());

ORA-01861: literal does not match format string

Just before executing the query: alter session set NLS_DATE_FORMAT = "DD.MM.YYYY HH24:MI:SS"; or whichever format you are giving the information to the date function. This should fix the ORA error

SQL Error: ORA-12899: value too large for column

As mentioned, the error message shows you the exact problem: you are passing 25 characters into a field set up to hold 20. You might also want to consider defining the columns a little more precisely. You can define whether the VARCHAR2 column will store a certain number of bytes or characters. You may encounter a problem in the future where you try to insert a multi byte character into the field, for example this is 5 characters in length but it won't fit into 5 bytes: 'ÀÈÌÕÛ'

Here is an example:

CREATE TABLE Customers(CustomerID  VARCHAR2(9 BYTE), ...

or

CREATE TABLE Customers(CustomerID  VARCHAR2(9 CHAR), ...

How do I check the difference, in seconds, between two dates?

import time  
current = time.time()

...job...
end = time.time()
diff = end - current

would that work for you?

warning: control reaches end of non-void function [-Wreturn-type]

You can also use EXIT_SUCCESS instead of return 0;. The macro EXIT_SUCCESS is actually defined as zero, but makes your program more readable.

Java ArrayList of Doubles

Try this,

ArrayList<Double> numb= new ArrayList<Double>(Arrays.asList(1.38, 2.56, 4.3));

MySQL Where DateTime is greater than today

SELECT * 
FROM customer 
WHERE joiningdate >= NOW();

Loop through a comma-separated shell variable

Here is an alternative tr based solution that doesn't use echo, expressed as a one-liner.

for v in $(tr ',' '\n' <<< "$var") ; do something_with "$v" ; done

It feels tidier without echo but that is just my personal preference.

What is the height of Navigation Bar in iOS 7?

I got this answer from the book Programming iOS 7, section Bar Position and Bar Metrics

If a navigation bar or toolbar — or a search bar (discussed earlier in this chapter) — is to occupy the top of the screen, the iOS 7 convention is that its height should be increased to underlap the transparent status bar. To make this possible, iOS 7 introduces the notion of a bar position.

UIBarPositionTopAttached

Specifies that the bar is at the top of the screen, as well as its containing view. Bars with this position draw their background extended upwards, allowing their background content to show through the status bar. Available in iOS 7.0 and later.

How to define constants in ReactJS

You don't need to use anything but plain React and ES6 to achieve what you want. As per Jim's answer, just define the constant in the right place. I like the idea of keeping the constant local to the component if not needed externally. The below is an example of possible usage.

import React from "react";

const sizeToLetterMap = {
  small_square: 's',
  large_square: 'q',
  thumbnail: 't',
  small_240: 'm',
  small_320: 'n',
  medium_640: 'z',
  medium_800: 'c',
  large_1024: 'b',
  large_1600: 'h',
  large_2048: 'k',
  original: 'o'
};

class PhotoComponent extends React.Component {
  constructor(args) {
    super(args);
  }

  photoUrl(image, size_text) {
    return (<span>
      Image: {image}, Size Letter: {sizeToLetterMap[size_text]}
    </span>);
  }

  render() {
    return (
      <div className="photo-wrapper">
        The url is: {this.photoUrl(this.props.image, this.props.size_text)}
      </div>
    )
  }
}

export default PhotoComponent;

// Call this with <PhotoComponent image="abc.png" size_text="thumbnail" />
// Of course the component must first be imported where used, example:
// import PhotoComponent from "./photo_component.jsx";

Detect click outside React component

Typescript with Hooks

Note: I'm using React version 16.3, with React.createRef. For other versions use the ref callback.

Dropdown component:

interface DropdownProps {
 ...
};

export const Dropdown: React.FC<DropdownProps> () {
  const ref: React.RefObject<HTMLDivElement> = React.createRef();
  
  const handleClickOutside = (event: MouseEvent) => {
    if (ref && ref !== null) {
      const cur = ref.current;
      if (cur && !cur.contains(event.target as Node)) {
        // close all dropdowns
      }
    }
  }

  useEffect(() => {
    // Bind the event listener
    document.addEventListener("mousedown", handleClickOutside);
    return () => {
      // Unbind the event listener on clean up
      document.removeEventListener("mousedown", handleClickOutside);
    };
  });

  return (
    <div ref={ref}>
        ...
    </div>
  );
}

How to highlight text using javascript

Simply pass your word into the following function:

function highlight_words(word) {
    const page = document.body.innerHTML;
    document.body.innerHTML = page.replace(new RegExp(word, "gi"), (match) => `<mark>${match}</mark>`);
}

Usage:

highlight_words("hello")

This will highlight all instances of the word on the page.

Change default text in input type="file"?

Update 2017:

I have done research on how this could be achieved. And the best explanation/tutorial is here: https://tympanus.net/codrops/2015/09/15/styling-customizing-file-inputs-smart-way/

I'll write summary here just in case it becomes unavailable. So you should have HTML:

<input type="file" name="file" id="file" class="inputfile" />
<label for="file">Choose a file</label>

Then hide the input with CSS:

.inputfile {
width: 0.1px;
height: 0.1px;
opacity: 0;
overflow: hidden;
position: absolute;
z-index: -1;}

Then style the label:

.inputfile + label {
font-size: 1.25em;
font-weight: 700;
color: white;
background-color: black;
display: inline-block;
}

Then optionally you can add JS to display the name of the file:

var inputs = document.querySelectorAll( '.inputfile' );
Array.prototype.forEach.call( inputs, function( input )
{
var label    = input.nextElementSibling,
    labelVal = label.innerHTML;

input.addEventListener( 'change', function( e )
{
    var fileName = '';
    if( this.files && this.files.length > 1 )
        fileName = ( this.getAttribute( 'data-multiple-caption' ) || '' ).replace( '{count}', this.files.length );
    else
        fileName = e.target.value.split( '\\' ).pop();

    if( fileName )
        label.querySelector( 'span' ).innerHTML = fileName;
    else
        label.innerHTML = labelVal;
});
});

But really just read the tutorial and download the demo, it's really good.

"undefined" function declared in another file?

If you want to call a function from another go file and you are using Goland, then find the option 'Edit configuration' from the Run menu and change the run kind from File to Directory. It clears all the errors and allows you to call functions from other go files.

Imported a csv-dataset to R but the values becomes factors

When importing csv data files the import command should reflect both the data seperation between each column (;) and the float-number seperator for your numeric values (for numerical variable = 2,5 this would be ",").

The command for importing a csv, therefore, has to be a bit more comprehensive with more commands:

    stuckey <- read.csv2("C:/kalle/R/stuckey.csv", header=TRUE, sep=";", dec=",")

This should import all variables as either integers or numeric.

Recursively find all files newer than a given time

Assuming a modern release, find -newermt is powerful:

find -newermt '10 minutes ago' ## other units work too, see `Date input formats`

or, if you want to specify a time_t (seconds since epoch):

find -newermt @1568670245

For reference, -newermt is not directly listed in the man page for find. Instead, it is shown as -newerXY, where XY are placeholders for mt. Other replacements are legal, but not applicable for this solution.

From man find -newerXY:

Time specifications are interpreted as for the argument to the -d option of GNU date.

So the following are equivalent to the initial example:

find -newermt "$(date '+%Y-%m-%d %H:%M:%S' -d '10 minutes ago')" ## long form using 'date'
find -newermt "@$(date +%s -d '10 minutes ago')" ## short form using 'date' -- notice '@'

The date -d (and find -newermt) arguments are quite flexible, but the documentation is obscure. Here's one source that seems to be on point: Date input formats

Redirect using AngularJS

Assuming you're not using html5 routing, try $location.path("route"). This will redirect your browser to #/route which might be what you want.

How to correctly save instance state of Fragments in back stack?

I just want to give the solution that I came up with that handles all cases presented in this post that I derived from Vasek and devconsole. This solution also handles the special case when the phone is rotated more than once while fragments aren't visible.

Here is were I store the bundle for later use since onCreate and onSaveInstanceState are the only calls that are made when the fragment isn't visible

MyObject myObject;
private Bundle savedState = null;
private boolean createdStateInDestroyView;
private static final String SAVED_BUNDLE_TAG = "saved_bundle";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState != null) {
        savedState = savedInstanceState.getBundle(SAVED_BUNDLE_TAG);
    }
}

Since destroyView isn't called in the special rotation situation we can be certain that if it creates the state we should use it.

@Override
public void onDestroyView() {
    super.onDestroyView();
    savedState = saveState();
    createdStateInDestroyView = true;
    myObject = null;
}

This part would be the same.

private Bundle saveState() { 
    Bundle state = new Bundle();
    state.putSerializable(SAVED_BUNDLE_TAG, myObject);
    return state;
}

Now here is the tricky part. In my onActivityCreated method I instantiate the "myObject" variable but the rotation happens onActivity and onCreateView don't get called. Therefor, myObject will be null in this situation when the orientation rotates more than once. I get around this by reusing the same bundle that was saved in onCreate as the out going bundle.

    @Override
public void onSaveInstanceState(Bundle outState) {

    if (myObject == null) {
        outState.putBundle(SAVED_BUNDLE_TAG, savedState);
    } else {
        outState.putBundle(SAVED_BUNDLE_TAG, createdStateInDestroyView ? savedState : saveState());
    }
    createdStateInDestroyView = false;
    super.onSaveInstanceState(outState);
}

Now wherever you want to restore the state just use the savedState bundle

  @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    ...
    if(savedState != null) {
        myObject = (MyObject) savedState.getSerializable(SAVED_BUNDLE_TAG);
    }
    ...
}

Simple Deadlock Examples

Here's a code example from the computer science department of a university in Taiwan showing a simple java example with resource locking. That's very "real-life" relevant to me. Code below:

/**
 * Adapted from The Java Tutorial
 * Second Edition by Campione, M. and
 * Walrath, K.Addison-Wesley 1998
 */

/**
 * This is a demonstration of how NOT to write multi-threaded programs.
 * It is a program that purposely causes deadlock between two threads that
 * are both trying to acquire locks for the same two resources.
 * To avoid this sort of deadlock when locking multiple resources, all threads
 * should always acquire their locks in the same order.
 **/
public class Deadlock {
  public static void main(String[] args){
    //These are the two resource objects 
    //we'll try to get locks for
    final Object resource1 = "resource1";
    final Object resource2 = "resource2";
    //Here's the first thread.
    //It tries to lock resource1 then resource2
    Thread t1 = new Thread() {
      public void run() {
        //Lock resource 1
        synchronized(resource1){
          System.out.println("Thread 1: locked resource 1");
          //Pause for a bit, simulating some file I/O or 
          //something. Basically, we just want to give the 
          //other thread a chance to run. Threads and deadlock
          //are asynchronous things, but we're trying to force 
          //deadlock to happen here...
          try{ 
            Thread.sleep(50); 
          } catch (InterruptedException e) {}

          //Now wait 'till we can get a lock on resource 2
          synchronized(resource2){
            System.out.println("Thread 1: locked resource 2");
          }
        }
      }
    };

    //Here's the second thread.  
    //It tries to lock resource2 then resource1
    Thread t2 = new Thread(){
      public void run(){
        //This thread locks resource 2 right away
        synchronized(resource2){
          System.out.println("Thread 2: locked resource 2");
          //Then it pauses, for the same reason as the first 
          //thread does
          try{
            Thread.sleep(50); 
          } catch (InterruptedException e){}

          //Then it tries to lock resource1.  
          //But wait!  Thread 1 locked resource1, and 
          //won't release it till it gets a lock on resource2.  
          //This thread holds the lock on resource2, and won't
          //release it till it gets resource1.  
          //We're at an impasse. Neither thread can run, 
          //and the program freezes up.
          synchronized(resource1){
            System.out.println("Thread 2: locked resource 1");
          }
        }
      }
    };

    //Start the two threads. 
    //If all goes as planned, deadlock will occur, 
    //and the program will never exit.
    t1.start(); 
    t2.start();
  }
}

Is there a way to make npm install (the command) to work behind proxy?

This worked for me. Set the http and https proxy.

PDO support for multiple queries (PDO_MYSQL, PDO_MYSQLND)

Try this function : mltiple queries and multiple values insertion.

function employmentStatus($Status) {
$pdo = PDO2::getInstance();

$sql_parts = array(); 
for($i=0; $i<count($Status); $i++){
    $sql_parts[] = "(:userID, :val$i)";
}

$requete = $pdo->dbh->prepare("DELETE FROM employment_status WHERE userid = :userID; INSERT INTO employment_status (userid, status) VALUES ".implode(",", $sql_parts));
$requete->bindParam(":userID", $_SESSION['userID'],PDO::PARAM_INT);
for($i=0; $i<count($Status); $i++){
    $requete->bindParam(":val$i", $Status[$i],PDO::PARAM_STR);
}
if ($requete->execute()) {
    return true;
}
return $requete->errorInfo();
}

How to remove origin from git repository

Remove existing origin and add new origin to your project directory

>$ git remote show origin

>$ git remote rm origin

>$ git add .

>$ git commit -m "First commit"

>$ git remote add origin Copied_origin_url

>$ git remote show origin

>$ git push origin master

How to suppress warnings globally in an R Script

You could use

options(warn=-1)

But note that turning off warning messages globally might not be a good idea.

To turn warnings back on, use

options(warn=0)

(or whatever your default is for warn, see this answer)

Iterate over elements of List and Map using JSTL <c:forEach> tag

Mark, this is already answered in your previous topic. But OK, here it is again:

Suppose ${list} points to a List<Object>, then the following

<c:forEach items="${list}" var="item">
    ${item}<br>
</c:forEach>

does basically the same as as following in "normal Java":

for (Object item : list) {
    System.out.println(item);
}

If you have a List<Map<K, V>> instead, then the following

<c:forEach items="${list}" var="map">
    <c:forEach items="${map}" var="entry">
        ${entry.key}<br>
        ${entry.value}<br>
    </c:forEach>
</c:forEach>

does basically the same as as following in "normal Java":

for (Map<K, V> map : list) {
    for (Entry<K, V> entry : map.entrySet()) {
        System.out.println(entry.getKey());
        System.out.println(entry.getValue());
    }
}

The key and value are here not special methods or so. They are actually getter methods of Map.Entry object (click at the blue Map.Entry link to see the API doc). In EL (Expression Language) you can use the . dot operator to access getter methods using "property name" (the getter method name without the get prefix), all just according the Javabean specification.

That said, you really need to cleanup the "answers" in your previous topic as they adds noise to the question. Also read the comments I posted in your "answers".

Get the difference between dates in terms of weeks, months, quarters, and years

Here's a solution:

dates <- c("14.01.2013", "26.03.2014")

# Date format:
dates2 <- strptime(dates, format = "%d.%m.%Y")

dif <- diff(as.numeric(dates2)) # difference in seconds

dif/(60 * 60 * 24 * 7) # weeks
[1] 62.28571
dif/(60 * 60 * 24 * 30) # months
[1] 14.53333
dif/(60 * 60 * 24 * 30 * 3) # quartes
[1] 4.844444
dif/(60 * 60 * 24 * 365) # years
[1] 1.194521

What causes: "Notice: Uninitialized string offset" to appear?

Check out the contents of your array with

echo '<pre>' . print_r( $arr, TRUE ) . '</pre>';

NULL or BLANK fields (ORACLE)

You can not count nulls (at least not in Oracle). Instead try this

SELECT count(1) FROM TABLE WHERE COL_NAME IS NULL

Determine if a String is an Integer in Java

You want to use the Integer.parseInt(String) method.

try{
  int num = Integer.parseInt(str);
  // is an integer!
} catch (NumberFormatException e) {
  // not an integer!
}

How to get the parents of a Python class?

If you want to ensure they all get called, use super at all levels.

C: socket connection timeout

This article might help:

Connect with timeout (or another use for select() )

Looks like you put the socket into non-blocking mode until you've connected, and then put it back into blocking mode once the connection's established.

void connect_w_to(void) { 
  int res; 
  struct sockaddr_in addr; 
  long arg; 
  fd_set myset; 
  struct timeval tv; 
  int valopt; 
  socklen_t lon; 

  // Create socket 
  soc = socket(AF_INET, SOCK_STREAM, 0); 
  if (soc < 0) { 
     fprintf(stderr, "Error creating socket (%d %s)\n", errno, strerror(errno)); 
     exit(0); 
  } 

  addr.sin_family = AF_INET; 
  addr.sin_port = htons(2000); 
  addr.sin_addr.s_addr = inet_addr("192.168.0.1"); 

  // Set non-blocking 
  if( (arg = fcntl(soc, F_GETFL, NULL)) < 0) { 
     fprintf(stderr, "Error fcntl(..., F_GETFL) (%s)\n", strerror(errno)); 
     exit(0); 
  } 
  arg |= O_NONBLOCK; 
  if( fcntl(soc, F_SETFL, arg) < 0) { 
     fprintf(stderr, "Error fcntl(..., F_SETFL) (%s)\n", strerror(errno)); 
     exit(0); 
  } 
  // Trying to connect with timeout 
  res = connect(soc, (struct sockaddr *)&addr, sizeof(addr)); 
  if (res < 0) { 
     if (errno == EINPROGRESS) { 
        fprintf(stderr, "EINPROGRESS in connect() - selecting\n"); 
        do { 
           tv.tv_sec = 15; 
           tv.tv_usec = 0; 
           FD_ZERO(&myset); 
           FD_SET(soc, &myset); 
           res = select(soc+1, NULL, &myset, NULL, &tv); 
           if (res < 0 && errno != EINTR) { 
              fprintf(stderr, "Error connecting %d - %s\n", errno, strerror(errno)); 
              exit(0); 
           } 
           else if (res > 0) { 
              // Socket selected for write 
              lon = sizeof(int); 
              if (getsockopt(soc, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &lon) < 0) { 
                 fprintf(stderr, "Error in getsockopt() %d - %s\n", errno, strerror(errno)); 
                 exit(0); 
              } 
              // Check the value returned... 
              if (valopt) { 
                 fprintf(stderr, "Error in delayed connection() %d - %s\n", valopt, strerror(valopt) 
); 
                 exit(0); 
              } 
              break; 
           } 
           else { 
              fprintf(stderr, "Timeout in select() - Cancelling!\n"); 
              exit(0); 
           } 
        } while (1); 
     } 
     else { 
        fprintf(stderr, "Error connecting %d - %s\n", errno, strerror(errno)); 
        exit(0); 
     } 
  } 
  // Set to blocking mode again... 
  if( (arg = fcntl(soc, F_GETFL, NULL)) < 0) { 
     fprintf(stderr, "Error fcntl(..., F_GETFL) (%s)\n", strerror(errno)); 
     exit(0); 
  } 
  arg &= (~O_NONBLOCK); 
  if( fcntl(soc, F_SETFL, arg) < 0) { 
     fprintf(stderr, "Error fcntl(..., F_SETFL) (%s)\n", strerror(errno)); 
     exit(0); 
  } 
  // I hope that is all 
}

warning: assignment makes integer from pointer without a cast

The warning comes from the fact that you're dereferencing src in the assignment. The expression *src has type char, which is an integral type. The expression "anotherstring" has type char [14], which in this particular context is implicitly converted to type char *, and its value is the address of the first character in the array. So, you wind up trying to assign a pointer value to an integral type, hence the warning. Drop the * from *src, and it should work as expected:

src = "anotherstring";

since the type of src is char *.

Make git automatically remove trailing whitespace before committing

You can trick Git into fixing the whitespace for you, by tricking Git into treating your changes as a patch. In contrast to the "pre-commit hook" solutions, these solutions add whitespace-fixing commands to Git.

Yes, these are hacks.


Robust solutions

The following Git aliases are taken from my ~/.gitconfig.

By "robust" I mean that these aliases run without error, doing the right thing, regardless of whether the tree or index are dirty. However, they don't work if an interactive git rebase -i is already in progress; see my ~/.gitconfig for additional checks if you care about this corner case, where the git add -e trick described at the end should work.

If you want to run them directly in the shell, without creating a Git alias, just copy and paste everything between the double quotes (assuming your shell is Bash like).

Fix the index but not the tree

The following fixws Git alias fixes all whitespace errors in the index, if any, but doesn't touch the tree:

# Logic:
#
# The 'git stash save' fails if the tree is clean (instead of
# creating an empty stash :P). So, we only 'stash' and 'pop' if
# the tree is dirty.
#
# The 'git rebase --whitespace=fix HEAD~' throws away the commit
# if it's empty, and adding '--keep-empty' prevents the whitespace
# from being fixed. So, we first check that the index is dirty.
#
# Also:
# - '(! git diff-index --quiet --cached HEAD)' is true (zero) if
#   the index is dirty
# - '(! git diff-files --quiet .)' is true if the tree is dirty
#
# The 'rebase --whitespace=fix' trick is from here:
# https://stackoverflow.com/a/19156679/470844
fixws = !"\
  if (! git diff-files --quiet .) && \
     (! git diff-index --quiet --cached HEAD) ; then \
    git commit -m FIXWS_SAVE_INDEX && \
    git stash save FIXWS_SAVE_TREE && \
    git rebase --whitespace=fix HEAD~ && \
    git stash pop && \
    git reset --soft HEAD~ ; \
  elif (! git diff-index --quiet --cached HEAD) ; then \
    git commit -m FIXWS_SAVE_INDEX && \
    git rebase --whitespace=fix HEAD~ && \
    git reset --soft HEAD~ ; \
  fi"

The idea is to run git fixws before git commit if you have whitespace errors in the index.

Fix the index and the tree

The following fixws-global-tree-and-index Git alias fixes all whitespace errors in the index and the tree, if any:

# The different cases are:
# - dirty tree and dirty index
# - dirty tree and clean index
# - clean tree and dirty index
#
# We have to consider separate cases because the 'git rebase
# --whitespace=fix' is not compatible with empty commits (adding
# '--keep-empty' makes Git not fix the whitespace :P).
fixws-global-tree-and-index = !"\
  if (! git diff-files --quiet .) && \
     (! git diff-index --quiet --cached HEAD) ; then \
    git commit -m FIXWS_SAVE_INDEX && \
    git add -u :/ && \
    git commit -m FIXWS_SAVE_TREE && \
    git rebase --whitespace=fix HEAD~2 && \
    git reset HEAD~ && \
    git reset --soft HEAD~ ; \
  elif (! git diff-files --quiet .) ; then \
    git add -u :/ && \
    git commit -m FIXWS_SAVE_TREE && \
    git rebase --whitespace=fix HEAD~ && \
    git reset HEAD~ ; \
  elif (! git diff-index --quiet --cached HEAD) ; then \
    git commit -m FIXWS_SAVE_INDEX && \
    git rebase --whitespace=fix HEAD~ && \
    git reset --soft HEAD~ ; \
  fi"

To also fix whitespace in unversioned files, do

git add --intent-to-add <unversioned files> && git fixws-global-tree-and-index

Simple but not robust solutions

These versions are easier to copy and paste, but they don't do the right thing if their side conditions are not met.

Fix the sub-tree rooted at the current directory (but resets the index if it's not empty)

Using git add -e to "edit" the patches with the identity editor ::

(export GIT_EDITOR=: && git -c apply.whitespace=fix add -ue .) && git checkout . && git reset

Fix and preserve the index (but fails if the tree is dirty or the index is empty)

git commit -m TEMP && git rebase --whitespace=fix HEAD~ && git reset --soft HEAD~

Fix the tree and the index (but resets the index if it's not empty)

git add -u :/ && git commit -m TEMP && git rebase --whitespace=fix HEAD~ && git reset HEAD~

Explanation of the export GIT_EDITOR=: && git -c apply.whitespace=fix add -ue . trick

Before I learned about the git rebase --whitespace=fix trick from this answer I was using the more complicated git add trick everywhere.

If we did it manually:

  1. Set apply.whitespace to fix (you only have to do this once):

    git config apply.whitespace fix
    

    This tells Git to fix whitespace in patches.

  2. Convince Git to treat your changes as a patch:

    git add -up .
    

    Hit a+enterto select all changes for each file. You'll get a warning about Git fixing your whitespace errors.
    (git -c color.ui=auto diff at this point reveals that your non-indexed changes are exactly the whitespace errors).

  3. Remove the whitespace errors from your working copy:

    git checkout .
    
  4. Bring back your changes (if you aren't ready to commit them):

    git reset
    

The GIT_EDITOR=: means to use : as the editor, and as a command : is the identity.

Convert a JSON String to a HashMap

Here is Vikas's code ported to JSR 353:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.json.JsonArray;
import javax.json.JsonException;
import javax.json.JsonObject;

public class JsonUtils {
    public static Map<String, Object> jsonToMap(JsonObject json) {
        Map<String, Object> retMap = new HashMap<String, Object>();

        if(json != JsonObject.NULL) {
            retMap = toMap(json);
        }
        return retMap;
    }

    public static Map<String, Object> toMap(JsonObject object) throws JsonException {
        Map<String, Object> map = new HashMap<String, Object>();

        Iterator<String> keysItr = object.keySet().iterator();
        while(keysItr.hasNext()) {
            String key = keysItr.next();
            Object value = object.get(key);

            if(value instanceof JsonArray) {
                value = toList((JsonArray) value);
            }

            else if(value instanceof JsonObject) {
                value = toMap((JsonObject) value);
            }
            map.put(key, value);
        }
        return map;
    }

    public static List<Object> toList(JsonArray array) {
        List<Object> list = new ArrayList<Object>();
        for(int i = 0; i < array.size(); i++) {
            Object value = array.get(i);
            if(value instanceof JsonArray) {
                value = toList((JsonArray) value);
            }

            else if(value instanceof JsonObject) {
                value = toMap((JsonObject) value);
            }
            list.add(value);
        }
        return list;
    }
}

Calling a method inside another method in same class

The add method that takes a String and a Person is calling a different add method that takes a Position. The one that takes Position is inherited from the ArrayList class.

Since your class Staff extends ArrayList<Position>, it automatically has the add(Position) method. The new add(String, Person) method is one that was written particularly for the Staff class.

Just what is an IntPtr exactly?

An IntPtr is a value type that is primarily used to hold memory addresses or handles. A pointer is a memory address. A pointer can be typed (e.g. int*) or untyped (e.g. void*). A Windows handle is a value that is usually the same size (or smaller) than a memory address and represents a system resource (like a file or window).

Is there Selected Tab Changed Event in the standard WPF Tab Control

I tied this in the handler to make it work:

void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    if (e.Source is TabControl)
    {
      //do work when tab is changed
    }
}

Html.BeginForm and adding properties

As part of htmlAttributes,e.g.

Html.BeginForm(
    action, controller, FormMethod.Post, new { enctype="multipart/form-data"})

Or you can pass null for action and controller to get the same default target as for BeginForm() without any parameters:

Html.BeginForm(
    null, null, FormMethod.Post, new { enctype="multipart/form-data"})

Cosine Similarity between 2 Number Lists

If you happen to be using PyTorch already, you should go with their CosineSimilarity implementation.

Suppose you have two n-dimensional numpy.ndarrays, v1 and v2, i.e. their shapes are both (n,). Here's how you get their cosine similarity:

import torch
import torch.nn as nn

cos = nn.CosineSimilarity()
cos(torch.tensor([v1]), torch.tensor([v2])).item()

Or suppose you have two numpy.ndarrays w1 and w2, whose shapes are both (m, n). The following gets you a list of cosine similarities, each being the cosine similarity between a row in w1 and the corresponding row in w2:

cos(torch.tensor(w1), torch.tensor(w2)).tolist()

How to give a user only select permission on a database

create LOGIN guest WITH PASSWORD='guest@123', CHECK_POLICY = OFF;

Be sure when you want to exceute the following

DENY VIEW ANY DATABASE TO guest;

ALTER AUTHORIZATION ON DATABASE::BiddingSystemDB TO guest

Selected Database should be Master

How to print a int64_t type in C

In windows environment, use

%I64d

in Linux, use

%lld

The correct way to read a data file into an array

open AAAA,"/filepath/filename.txt";
my @array = <AAAA>; # read the file into an array of lines
close AAAA;

Regex Explanation ^.*$

  • ^ matches position just before the first character of the string
  • $ matches position just after the last character of the string
  • . matches a single character. Does not matter what character it is, except newline
  • * matches preceding match zero or more times

So, ^.*$ means - match, from beginning to end, any character that appears zero or more times. Basically, that means - match everything from start to end of the string. This regex pattern is not very useful.

Let's take a regex pattern that may be a bit useful. Let's say I have two strings The bat of Matt Jones and Matthew's last name is Jones. The pattern ^Matt.*Jones$ will match Matthew's last name is Jones. Why? The pattern says - the string should start with Matt and end with Jones and there can be zero or more characters (any characters) in between them.

Feel free to use an online tool like https://regex101.com/ to test out regex patterns and strings.

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

An simple method :

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

    return dateRetour;
}

Convert alphabet letters to number in Python

You can use chr() and ord() to convert betweeen letters and int numbers.

Here is a simple example.

>>> chr(97)
'a'
>>> ord('a')
97

jquery.ajax Access-Control-Allow-Origin

http://encosia.com/using-cors-to-access-asp-net-services-across-domains/

refer the above link for more details on Cross domain resource sharing.

you can try using JSONP . If the API is not supporting jsonp, you have to create a service which acts as a middleman between the API and your client. In my case, i have created a asmx service.

sample below:

ajax call:

$(document).ready(function () {
        $.ajax({
            crossDomain: true,
            type:"GET",
            contentType: "application/json; charset=utf-8",
            async:false,
            url: "<your middle man service url here>/GetQuote?callback=?",
            data: { symbol: 'ctsh' },
            dataType: "jsonp",                
            jsonpCallback: 'fnsuccesscallback'
        });
    });

service (asmx) which will return jsonp:

[WebMethod]
    [ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
    public void GetQuote(String symbol,string callback)
    {          

        WebProxy myProxy = new WebProxy("<proxy url here>", true);

        myProxy.Credentials = new System.Net.NetworkCredential("username", "password", "domain");
        StockQuoteProxy.StockQuote SQ = new StockQuoteProxy.StockQuote();
        SQ.Proxy = myProxy;
        String result = SQ.GetQuote(symbol);
        StringBuilder sb = new StringBuilder();
        JavaScriptSerializer js = new JavaScriptSerializer();
        sb.Append(callback + "(");
        sb.Append(js.Serialize(result));
        sb.Append(");");
        Context.Response.Clear();
        Context.Response.ContentType = "application/json";
        Context.Response.Write(sb.ToString());
        Context.Response.End();         
    }

How to count digits, letters, spaces for a string in Python?


# Write a Python program that accepts a string and calculate the number of digits 
# andletters.

    stre =input("enter the string-->")
    countl = 0
    countn = 0
    counto = 0
    for i in stre:
        if i.isalpha():
            countl += 1
        elif i.isdigit():
            countn += 1
        else:
            counto += 1
    print("The number of letters are --", countl)
    print("The number of numbers are --", countn)
    print("The number of characters are --", counto)

Check last modified date of file in C#

Just use File.GetLastWriteTime. There's a sample on that page showing how to use it.

ant warning: "'includeantruntime' was not set"

If you like me work from commandline the quick answer is executing

export ANT_OPTS=-Dbuild.sysclasspath=ignore

And then run your ant script again.

UTF-8 text is garbled when form is posted as multipart/form-data

Just use Apache commons upload library. Add URIEncoding="UTF-8" to Tomcat's connector, and use FileItem.getString("UTF-8") instead of FileItem.getString() without charset specified.

Hope this help.

Assign output to variable in Bash

In shell, you don't put a $ in front of a variable you're assigning. You only use $IP when you're referring to the variable.

#!/bin/bash

IP=$(curl automation.whatismyip.com/n09230945.asp)

echo "$IP"

sed "s/IP/$IP/" nsupdate.txt | nsupdate

iOS - Ensure execution on main thread

there any rule I can follow to be sure that my app executes my own code just in the main thread?

Typically you wouldn't need to do anything to ensure this — your list of things is usually enough. Unless you're interacting with some API that happens to spawn a thread and run your code in the background, you'll be running on the main thread.

If you want to be really sure, you can do things like

[self performSelectorOnMainThread:@selector(myMethod:) withObject:anObj waitUntilDone:YES];

to execute a method on the main thread. (There's a GCD equivalent too.)

c# replace \" characters

\ => \\ and " => \"

so Replace("\\\"","")

'was not declared in this scope' error

The scope of a variable is always the block it is inside. For example if you do something like

if(...)
{
     int y = 5; //y is created
} //y leaves scope, since the block ends.
else
{
     int y = 8; //y is created
} //y leaves scope, since the block ends.

cout << y << endl; //Gives error since y is not defined.

The solution is to define y outside of the if blocks

int y; //y is created

if(...)
{
     y = 5;
} 
else
{
     y = 8;
} 

cout << y << endl; //Ok

In your program you have to move the definition of y and c out of the if blocks into the higher scope. Your Function then would look like this:

//Using the Gaussian algorithm
int dayofweek(int date, int month, int year )
{
    int y, c;
    int d=date;

    if (month==1||month==2)
    {
         y=((year-1)%100);
         c=(year-1)/100;
    }
    else
    {
         y=year%100;
         c=year/100;
    }
int m=(month+9)%12+1;
int product=(d+(2.6*m-0.2)+y+y/4+c/4-2*c);
return product%7;
}

Opacity of div's background without affecting contained element in IE 8?

it's simple only you have do is to give

background: rgba(0,0,0,0.3)

& for IE use this filter

background: transparent;
zoom: 1;    
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#4C000000,endColorstr=#4C000000); /* IE 6 & 7 */
-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#4C000000,endColorstr=#4C000000)"; /* IE8 */

you can generate your rgba filter from here http://kimili.com/journal/rgba-hsla-css-generator-for-internet-explorer/

How to Write text file Java

It's not creating a file because you never actually created the file. You made an object for it. Creating an instance doesn't create the file.

File newFile = new File("directory", "fileName.txt");

You can do this to make a file:

newFile.createNewFile();

You can do this to make a folder:

newFile.mkdir();

The CodeDom provider type "Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider" could not be located

Go to inetmgr from start command In IIS manager console choose the application folder under Default Web Site right click on that folder then Convert to Application Run the .asmx file by Enabling It solved the problem

How to run mysql command on bash?

I have written a shell script which will read data from properties file and then run mysql script on shell script. sharing this may help to others.

#!/bin/bash
    PROPERTY_FILE=filename.properties

    function getProperty {
       PROP_KEY=$1
       PROP_VALUE=`cat $PROPERTY_FILE | grep "$PROP_KEY" | cut -d'=' -f2`
       echo $PROP_VALUE
    }

    echo "# Reading property from $PROPERTY_FILE"
    DB_USER=$(getProperty "db.username")
    DB_PASS=$(getProperty "db.password")
    ROOT_LOC=$(getProperty "root.location")
    echo $DB_USER
    echo $DB_PASS
    echo $ROOT_LOC
    echo "Writing on DB ... "
    mysql -u$DB_USER -p$DB_PASS dbname<<EOFMYSQL

    update tablename set tablename.value_ = "$ROOT_LOC" where tablename.name_="Root directory location";
    EOFMYSQL
    echo "Writing root location($ROOT_LOC) is done ... "
    counter=`mysql -u${DB_USER} -p${DB_PASS} dbname -e "select count(*) from tablename where tablename.name_='Root directory location' and tablename.value_ = '$ROOT_LOC';" | grep -v "count"`;

    if [ "$counter" = "1" ]
    then
    echo "ROOT location updated"
    fi

How to set the "Content-Type ... charset" in the request header using a HTML link

This is not possible from HTML on. The closest what you can get is the accept-charset attribute of the <form>. Only MSIE browser adheres that, but even then it is doing it wrong (e.g. CP1252 is actually been used when it says that it has sent ISO-8859-1). Other browsers are fully ignoring it and they are using the charset as specified in the Content-Type header of the response. Setting the character encoding right is basically fully the responsiblity of the server side. The client side should just send it back in the same charset as the server has sent the response in.

To the point, you should really configure the character encoding stuff entirely from the server side on. To overcome the inability to edit URIEncoding attribute, someone here on SO wrote a (complex) filter: Detect the URI encoding automatically in Tomcat. You may find it useful as well (note: I haven't tested it).


Update: Noted should be that the meta tag as given in your question is ignored when the content is been transferred over HTTP. Instead, the HTTP response Content-Type header will be used to determine the content type and character encoding. You can determine the HTTP header with for example Firebug, in the Net panel.

alt text

Entity Framework Core: A second operation started on this context before a previous operation completed

My situation is different: I was trying to seed the database with 30 users, belonging to specific roles, so I was running this code:

for (var i = 1; i <= 30; i++)
{
    CreateUserWithRole("Analyst", $"analyst{i}", UserManager);
}

This was a Sync function. Inside of it I had 3 calls to:

UserManager.FindByNameAsync(username).Result
UserManager.CreateAsync(user, pass).Result
UserManager.AddToRoleAsync(user, roleName).Result

When I replaced .Result with .GetAwaiter().GetResult(), this error went away.

Allowed memory size of X bytes exhausted

1 check current limit:
(in my os)php -i | grep limit  => memory_limit => 256M => 256M

2  locate php.ini 
php --ini =>   
Configuration File (php.ini) Path: /etc
Loaded Configuration File:         /etc/php.ini
Scan for additional .ini files in: /etc/php.d
Additional .ini files parsed:      /etc/php.d/curl.ini 
...

3 change memory_limit in php.ini
vi /etc/php.ini
memory_limit = 512M

4 restart nginx and (php-fpm if being used)
service php-fpm restart
service nginx restart

Number of lines in a file in Java

Best Optimized code for multi line files having no newline('\n') character at EOF.

/**
 * 
 * @param filename
 * @return
 * @throws IOException
 */
public static int countLines(String filename) throws IOException {
    int count = 0;
    boolean empty = true;
    FileInputStream fis = null;
    InputStream is = null;
    try {
        fis = new FileInputStream(filename);
        is = new BufferedInputStream(fis);
        byte[] c = new byte[1024];
        int readChars = 0;
        boolean isLine = false;
        while ((readChars = is.read(c)) != -1) {
            empty = false;
            for (int i = 0; i < readChars; ++i) {
                if ( c[i] == '\n' ) {
                    isLine = false;
                    ++count;
                }else if(!isLine && c[i] != '\n' && c[i] != '\r'){   //Case to handle line count where no New Line character present at EOF
                    isLine = true;
                }
            }
        }
        if(isLine){
            ++count;
        }
    }catch(IOException e){
        e.printStackTrace();
    }finally {
        if(is != null){
            is.close();    
        }
        if(fis != null){
            fis.close();    
        }
    }
    LOG.info("count: "+count);
    return (count == 0 && !empty) ? 1 : count;
}

How do I clone a generic List in Java?

I find using addAll works fine.

ArrayList<String> copy = new ArrayList<String>();
copy.addAll(original);

parentheses are used rather than the generics syntax

Java Generate Random Number Between Two Given Values

One can also try below:

public class RandomInt { 
    public static void main(String[] args) { 

        int n1 = Integer.parseInt(args[0]);
        int n2 = Integer.parseInt(args[1]);
        double Random;

        if (n1 != n2)
        {
            if (n1 > n2)
            {
                Random = n2 + (Math.random() * (n1 - n2));
                System.out.println("Your random number is: " + Random);
            }
            else
            {
                Random = n1 + (Math.random() * (n2 - n1));   
                System.out.println("Your random number is: " +Random);
            }
        } else {
            System.out.println("Please provide valid Range " +n1+ " " +n2+ " are equal numbers." );
        }                     
    }
}

How do I perform query filtering in django templates

For anyone looking for an answer in 2020. This worked for me.

In Views:

 class InstancesView(generic.ListView):
        model = AlarmInstance
        context_object_name = 'settings_context'
        queryset = Group.objects.all()
        template_name = 'insta_list.html'

        @register.filter
        def filter_unknown(self, aVal):
            result = aVal.filter(is_known=False)
            return result

        @register.filter
        def filter_known(self, aVal):
            result = aVal.filter(is_known=True)
            return result

In template:

{% for instance in alarm.qar_alarm_instances|filter_unknown:alarm.qar_alarm_instances %}

In pseudocode:

For each in model.child_object|view_filter:filter_arg

Hope that helps.

Adding padding to a tkinter widget only on one side

The padding options padx and pady of the grid and pack methods can take a 2-tuple that represent the left/right and top/bottom padding.

Here's an example:

import tkinter as tk

class MyApp():
    def __init__(self):
        self.root = tk.Tk()
        l1 = tk.Label(self.root, text="Hello")
        l2 = tk.Label(self.root, text="World")
        l1.grid(row=0, column=0, padx=(100, 10))
        l2.grid(row=1, column=0, padx=(10, 100)) 

app = MyApp()
app.root.mainloop()

How to change the default docker registry from docker.io to my private registry?

if you are using the fedora distro, you can change the file

/etc/containers/registries.conf

Adding domain docker.io

Spring: how do I inject an HttpServletRequest into a request-scoped bean?

Request-scoped beans can be autowired with the request object.

private @Autowired HttpServletRequest request;

Two dimensional array in python

x=3#rows
y=3#columns
a=[]#create an empty list first
for i in range(x):
    a.append([0]*y)#And again append empty lists to original list
    for j in range(y):
         a[i][j]=input("Enter the value")

CSS :selected pseudo class similar to :checked, but for <select> elements

the :checked pseudo-class initially applies to such elements that have the HTML4 selected and checked attributes

Source: w3.org


So, this CSS works, although styling the color is not possible in every browser:

option:checked { color: red; }

An example of this in action, hiding the currently selected item from the drop down list.

_x000D_
_x000D_
option:checked { display:none; }
_x000D_
<select>_x000D_
    <option>A</option>_x000D_
    <option>B</option>_x000D_
    <option>C</option>_x000D_
</select>
_x000D_
_x000D_
_x000D_


To style the currently selected option in the closed dropdown as well, you could try reversing the logic:

select { color: red; }
option:not(:checked) { color: black; } /* or whatever your default style is */

How can I tell which button was clicked in a PHP form submit?

Are you asking in php or javascript.

If it is in php, give the name of that and use the post or get method, after that you can use the option of isset or that particular button name is checked to that value.

If it is in js, use getElementById for that

How to format date string in java?

use SimpleDateFormat to first parse() String to Date and then format() Date to String