Programs & Examples On #Drb

Why does C++ code for testing the Collatz conjecture run faster than hand-written assembly?

You did not post the code generated by the compiler, so there' some guesswork here, but even without having seen it, one can say that this:

test rax, 1
jpe even

... has a 50% chance of mispredicting the branch, and that will come expensive.

The compiler almost certainly does both computations (which costs neglegibly more since the div/mod is quite long latency, so the multiply-add is "free") and follows up with a CMOV. Which, of course, has a zero percent chance of being mispredicted.

Angular2 get clicked element id

There is no need to pass the entire event (unless you need other aspects of the event than you have stated). In fact, it is not recommended. You can pass the element reference with just a little modification.

import {Component} from 'angular2/core';

  selector: 'my-app',
  template: `
    <button #btn1 (click)="toggle(btn1)" class="someclass" id="btn1">Button 1</button>
    <button #btn2 (click)="toggle(btn2)" class="someclass" id="btn2">Button 2</button>
export class AppComponent {
  buttonValue: string;

  toggle(button) {
    this.buttonValue =;


StackBlitz demo

Technically, you don't need to find the button that was clicked, because you have passed the actual element.

Angular guidance

ERROR 403 in loading resources like CSS and JS in my index.php

You need to change permissions on the folder bootstrap/css. Your super user may be able to access it but it doesn't mean apache or nginx have access to it, that's why you still need to change the permissions.

Tip: I usually make the apache/nginx's user group owner of that kind of folders and give 775 permission to it.

How to query values from xml nodes?

This works, been tested...

SELECT  n.c.value('OrganizationReportReferenceIdentifier[1]','varchar(128)') AS 'OrganizationReportReferenceNumber',  
        n.c.value('(OrganizationNumber)[1]','varchar(128)') AS 'OrganizationNumber'
FROM    Batches t
Cross   Apply RawXML.nodes('/GrobXmlFile/Grob/ReportHeader') n(c)  

IntelliJ IDEA generating serialVersionUID

I am not sure if you have an old version of IntelliJ IDEA, but if I go to menu File ? Settings... ? Inspections ? Serialization issues ? Serializable class without 'serialVersionUID'` enabled, the class you provide give me warnings.

Enter image description here

If I try the first class I see:

Enter image description here

BTW: It didn't show me a warning until I added { } to the end of each class to fix the compile error.

Eclipse C++ : "Program "g++" not found in PATH"

First Install MinGW or other C/C++ compiler as it's required by Eclipse C++.

Use as unbelievably the's version has malware attached.

Back to Eclipse.

Now in all those path settings that the Eclipse Help manual talks about INSTEAD of typing the path, Select Variables and


and do so for all instances which would ask for the compiler's path.

First would be to click Preferences of the whatever project and C/C++ General then Paths and Symbols and add the

**MINGW_HOME** to those paths of for the compiler.

Next simply add the home directory to the Build Variables under the C++/C Build

Build Variables Screen Capture

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

They have wrapped most stuff need to solve your problem, one of the tests looks like this:

String filename = CSSURLEmbedderTest.class.getResource("folder.png").getPath().replace("%20", " ");
String code = "background: url(folder.png);";

StringWriter writer = new StringWriter();
embedder = new CSSURLEmbedder(new StringReader(code), true);
embedder.embedImages(writer, filename.substring(0, filename.lastIndexOf("/")+1));

String result = writer.toString();
assertEquals("background: url(" + folderDataURI + ");", result);

Python base64 data decode

base64 encode/decode example:

import base64

mystr = 'O João mordeu o cão!'

# Encode
mystr_encoded = base64.b64encode(mystr.encode('utf-8'))
# b'TyBKb8OjbyBtb3JkZXUgbyBjw6NvIQ=='

# Decode
mystr_encoded = base64.b64decode(mystr_encoded).decode('utf-8')
# 'O João mordeu o cão!'

Sass and combined child selector

For that single rule you have, there isn't any shorter way to do it. The child combinator is the same in CSS and in Sass/SCSS and there's no alternative to it.

However, if you had multiple rules like this:

#foo > ul > li > ul > li > a:nth-child(3n+1) {
    color: red;

#foo > ul > li > ul > li > a:nth-child(3n+2) {
    color: green;

#foo > ul > li > ul > li > a:nth-child(3n+3) {
    color: blue;

You could condense them to one of the following:

/* Sass */
#foo > ul > li > ul > li
    > a:nth-child(3n+1)
        color: red
    > a:nth-child(3n+2)
        color: green
    > a:nth-child(3n+3)
        color: blue

/* SCSS */
#foo > ul > li > ul > li {
    > a:nth-child(3n+1) { color: red; }
    > a:nth-child(3n+2) { color: green; }
    > a:nth-child(3n+3) { color: blue; }

MySQL SELECT only not null values

You should use IS NOT NULL. (The comparison operators = and <> both give UNKNOWN with NULL on either side of the expression.)

FROM table 

Just for completeness I'll mention that in MySQL you can also negate the null safe equality operator but this is not standard SQL.

FROM table 
WHERE NOT (YourColumn <=> NULL);

Edited to reflect comments. It sounds like your table may not be in first normal form in which case changing the structure may make your task easier. A couple of other ways of doing it though...

SELECT val1 AS val
FROM  your_table
SELECT val2 
FROM  your_table
/*And so on for all your columns*/

The disadvantage of the above is that it scans the table multiple times once for each column. That may possibly be avoided by the below but I haven't tested this in MySQL.

         WHEN 1 THEN val1
         WHEN 2 THEN val2
       END AS val
FROM   your_table
        /*CROSS JOIN*/
       JOIN (SELECT 1 AS idx
                   UNION ALL
                   SELECT 2) t
HAVING val IS NOT NULL  /*Can reference alias in Having in MySQL*/

HTML Text with tags to formatted text in an Excel cell

Yes it is possible :) In fact let Internet Explorer do the dirty work for you ;)



  1. I am assuming that the html text is in Cell A1 of Sheet1. You can also use a variable instead.
  2. If you have a column full of html values, then simply put the below code in a loop

CODE (See NOTE at the end)

Sub Sample()
    Dim Ie As Object
    Set Ie = CreateObject("InternetExplorer.Application")
    With Ie
        .Visible = False
        .Navigate "about:blank"
        .document.body.InnerHTML = Sheets("Sheet1").Range("A1").Value
        .document.body.createtextrange.execCommand "Copy"
        ActiveSheet.Paste Destination:=Sheets("Sheet1").Range("A1")
    End With
End Sub


enter image description here

NOTE: Thanks to @tiQu answer below. The above code will work with new IE if you replace .document.body.createtextrange.execCommand "Copy" with .ExecWB 17, 0: .ExecWB 12, 2 as suggested by him.

X close button only using css

<div style="width: 10px; height: 10px; position: relative; display: flex; justify-content: center;">
   <div style="width: 1.5px; height: 100%; background-color: #9c9f9c; position: absolute; transform: rotate(45deg); border-radius: 2px;"></div>
   <div style="width: 1.5px; height: 100%; background-color: #9c9f9c; position: absolute; transform: rotate(-45deg); border-radius: 2px;"></div>

JavaScript to get rows count of a HTML table


Is there a way to instantiate a class by name in Java?

use Class.forName("String name of class").newInstance();


This will cause class named A initialized.

React Native fetch() Network Request Failed

For Android user:

  1. Replace localhosts to a Lan IP addresses because when you run the project on an Android device, localhost is pointing to the Android device, instead of your computer, example: change http://localost to

  2. If your request URL is HTTPS and your Android device is under a proxy, assume you have installed User-added CA(like burp suite's CA or Charles's CA) in your Android device, make sure your Android version is below Nougat(7.0), because: Changes to Trusted Certificate Authorities in Android Nougat

    User-added CAs
    Protection of all application data is a key goal of the Android application sandbox. Android Nougat changes how applications interact with user- and admin-supplied CAs. By default, apps that target API level 24 will—by design—not honor such CAs unless the app explicitly opts in. This safe-by-default setting reduces application attack surface and encourages consistent handling of network and file-based application data.

How to call a button click event from another method

we have 2 form in this project. in main form change

private void button1_Click(object sender, EventArgs e) { // work }


public void button1_Click(object sender, EventArgs e) { // work }

and in other form, when we need above function

        private void button2_Click(object sender, EventArgs e)
        main_page() obj = new main_page();
        obj.button2_Click(sender, e);

Division in Python 2.7. and 3.3

"/" is integer division in python 2 so it is going to round to a whole number. If you would like a decimal returned, just change the type of one of the inputs to float:

float(20)/15 #1.33333333

How to add trendline in python matplotlib dot (scatter) graphs?

as explained here

With help from numpy one can calculate for example a linear fitting.

# plot the data itself

# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])

Cache an HTTP 'Get' service response in AngularJS?

In Angular 8 we can do like this:

import { Injectable } from '@angular/core';
import { YourModel} from '../models/<yourModel>.model';
import { UserService } from './user.service';
import { Observable, of } from 'rxjs';
import { map, catchError } from 'rxjs/operators';
import { HttpClient } from '@angular/common/http';

  providedIn: 'root'

export class GlobalDataService {

  private me: <YourModel>;

  private meObservable: Observable<User>;

  constructor(private yourModalService: <yourModalService>, private http: HttpClient) {


  ngOnInit() {


  getYourModel(): Observable<YourModel> {

    if ( {
      return of(;
    } else if (this.meObservable) {
      return this.meObservable;
    else {
      this.meObservable = this.yourModalService.getCall<yourModel>() // Your http call
        map(data => {
 = data;
          return data;
      return this.meObservable;

You can call it like this:

this.globalDataService.getYourModel().subscribe(yourModel => {


The above code will cache the result of remote API at first call so that it can be used on further requests to that method.

How do I search an SQL Server database for a string?

You can export your database (if small) to your hard drive / desktop, and then just do a string search via a text search program or text editor.

Finding the path of the program that will execute from the command line in Windows

Here's a little cmd script you can copy-n-paste into a file named something like where.cmd:

@echo off
rem - search for the given file in the directories specified by the path, and display the first match
rem    The main ideas for this script were taken from Raymond Chen's blog:
rem - it'll be nice to at some point extend this so it won't stop on the first match. That'll
rem     help diagnose situations with a conflict of some sort.


rem - search the current directory as well as those in the path

if not "%EXTLIST%" == "" goto :extlist_ok

rem - first look for the file as given (not adding extensions)
for %%i in (%1) do if NOT "%%~$PATHLIST:i"=="" echo %%~$PATHLIST:i

rem - now look for the file adding extensions from the EXTLIST
for %%e in (%EXTLIST%) do @for %%i in (%1%%e) do if NOT "%%~$PATHLIST:i"=="" echo %%~$PATHLIST:i

How to add a “readonly” attribute to an <input>?

jQuery <1.9

$('#inputId').attr('readonly', true);

jQuery 1.9+

$('#inputId').prop('readonly', true);

Read more about difference between prop and attr

How to sum digits of an integer in java?

public static void main(String[] args) {
        int num = 321;
        int sum = 0;
        while (num > 0) {
            sum = sum + num % 10;
            num = num / 10;



Parse JSON String into List<string>

Try this:

using System;
using Newtonsoft.Json;
using System.Collections.Generic;
public class Program
    public static void Main()
        List<Man> Men = new List<Man>();

        Man m1 = new Man();
        m1.Number = "+1-9169168158";
        m1.Message = "Hello Bob from 1";
        m1.UniqueCode = "0123";
        m1.State = 0;

        Man m2 = new Man();
        m2.Number = "+1-9296146182";
        m2.Message = "Hello Bob from 2";
        m2.UniqueCode = "0125";
        m2.State = 0;

        Men.AddRange(new Man[] { m1, m2 });

        string result = JsonConvert.SerializeObject(Men);

        List<Man> NewMen = JsonConvert.DeserializeObject<List<Man>>(result);
        foreach(Man m in NewMen) Console.WriteLine(m.Message);
public class Man
    public string Number{get;set;}
    public string Message {get;set;}
    public string UniqueCode {get;set;}
    public int State {get;set;}

Laravel Soft Delete posts

In the Latest version of Laravel i.e above Laravel 5.0. It is quite simple to perform this task. In Model, inside the class just write 'use SoftDeletes'. Example


namespace App;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class User extends Model
    use SoftDeletes;

And In Controller, you can do deletion. Example

User::where('email', '[email protected]')->delete();


User::where('email', '[email protected]')->softDeletes();

Make sure that you must have 'deleted_at' column in the users Table.

Permission denied on CopyFile in VBS

I have read your problem, And i had the same problem. But af ter i changed some, my problem "Permission Denied" is solved.

Private Sub Addi_Click()
'On Error Resume Next
'call ds
browsers ("false")
Call makeAdir
ffgg = "C:\Users\Backups\user\" & User & "1\data\"
Set fs = CreateObject("Scripting.FileSystemObject")
    Set f = fs.Getfolder("c:\users\Backups\user\" & User & "1\data")
    f.Attributes = 0
Set fso = VBA.CreateObject("Scripting.FileSystemObject")
Call fso.Copyfile(filetarget, ffgg, True)

Look at ffgg = "C:\Users\Backups\user\" & User & "1\data\", Before I changed it was ffgg = "C:\Users\Backups\user\" & User & "1\data" When i add backslash after "\data\", my problem is solved. Try to add back slash. Maybe solved your problem. Good luck.

How to read .pem file to get private and public key

One option is to use bouncycastle's PEMParser:

Class for parsing OpenSSL PEM encoded streams containing X509 certificates, PKCS8 encoded keys and PKCS7 objects.

In the case of PKCS7 objects the reader will return a CMS ContentInfo object. Public keys will be returned as well formed SubjectPublicKeyInfo objects, private keys will be returned as well formed PrivateKeyInfo objects. In the case of a private key a PEMKeyPair will normally be returned if the encoding contains both the private and public key definition. CRLs, Certificates, PKCS#10 requests, and Attribute Certificates will generate the appropriate BC holder class.

Here is an example of using the Parser test code:

package org.bouncycastle.openssl.test;

import java.math.BigInteger;

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.cms.CMSObjectIdentifiers;
import org.bouncycastle.asn1.cms.ContentInfo;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.asn1.x9.ECNamedCurveTable;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMDecryptorProvider;
import org.bouncycastle.openssl.PEMEncryptedKeyPair;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.PEMWriter;
import org.bouncycastle.openssl.PasswordFinder;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.bouncycastle.openssl.jcajce.JceOpenSSLPKCS8DecryptorProviderBuilder;
import org.bouncycastle.openssl.jcajce.JcePEMDecryptorProviderBuilder;
import org.bouncycastle.operator.InputDecryptorProvider;
import org.bouncycastle.pkcs.PKCS8EncryptedPrivateKeyInfo;
import org.bouncycastle.util.test.SimpleTest;

 * basic class for reading test.pem - the password is "secret"
public class ParserTest
    extends SimpleTest
    private static class Password
        implements PasswordFinder
        char[]  password;

            char[] word)
            this.password = word;

        public char[] getPassword()
            return password;

    public String getName()
        return "PEMParserTest";

    private PEMParser openPEMResource(
        String          fileName)
        InputStream res = this.getClass().getResourceAsStream(fileName);
        Reader fRd = new BufferedReader(new InputStreamReader(res));
        return new PEMParser(fRd);

    public void performTest()
        throws Exception
        PEMParser       pemRd = openPEMResource("test.pem");
        Object          o;
        PEMKeyPair      pemPair;
        KeyPair         pair;

        while ((o = pemRd.readObject()) != null)
            if (o instanceof KeyPair)
                //pair = (KeyPair)o;


        // test bogus lines before begin are ignored.
        pemRd = openPEMResource("extratest.pem");

        while ((o = pemRd.readObject()) != null)
            if (!(o instanceof X509CertificateHolder))
                fail("wrong object found");

        // pkcs 7 data
        pemRd = openPEMResource("pkcs7.pem");
        ContentInfo d = (ContentInfo)pemRd.readObject();

        if (!d.getContentType().equals(CMSObjectIdentifiers.envelopedData))
            fail("failed envelopedData check");

        // ECKey
        pemRd = openPEMResource("eckey.pem");
        ASN1ObjectIdentifier ecOID = (ASN1ObjectIdentifier)pemRd.readObject();
        X9ECParameters ecSpec = ECNamedCurveTable.getByOID(ecOID);

        if (ecSpec == null)
            fail("ecSpec not found for named curve");

        pemPair = (PEMKeyPair)pemRd.readObject();

        pair = new JcaPEMKeyConverter().setProvider("BC").getKeyPair(pemPair);

        Signature sgr = Signature.getInstance("ECDSA", "BC");


        byte[] message = new byte[] { (byte)'a', (byte)'b', (byte)'c' };


        byte[]  sigBytes = sgr.sign();



        if (!sgr.verify(sigBytes))
            fail("EC verification failed");

        if (!pair.getPublic().getAlgorithm().equals("ECDSA"))
            fail("wrong algorithm name on public got: " + pair.getPublic().getAlgorithm());

        if (!pair.getPrivate().getAlgorithm().equals("ECDSA"))
            fail("wrong algorithm name on private");

        // ECKey -- explicit parameters
        pemRd = openPEMResource("ecexpparam.pem");
        ecSpec = (X9ECParameters)pemRd.readObject();

        pemPair = (PEMKeyPair)pemRd.readObject();

        pair = new JcaPEMKeyConverter().setProvider("BC").getKeyPair(pemPair);

        sgr = Signature.getInstance("ECDSA", "BC");


        message = new byte[] { (byte)'a', (byte)'b', (byte)'c' };


        sigBytes = sgr.sign();



        if (!sgr.verify(sigBytes))
            fail("EC verification failed");

        if (!pair.getPublic().getAlgorithm().equals("ECDSA"))
            fail("wrong algorithm name on public got: " + pair.getPublic().getAlgorithm());

        if (!pair.getPrivate().getAlgorithm().equals("ECDSA"))
            fail("wrong algorithm name on private");

        // writer/parser test
        KeyPairGenerator      kpGen = KeyPairGenerator.getInstance("RSA", "BC");

        pair = kpGen.generateKeyPair();

        keyPairTest("RSA", pair);

        kpGen = KeyPairGenerator.getInstance("DSA", "BC");
        kpGen.initialize(512, new SecureRandom());
        pair = kpGen.generateKeyPair();

        keyPairTest("DSA", pair);

        // PKCS7
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        PEMWriter             pWrt = new PEMWriter(new OutputStreamWriter(bOut));



        pemRd = new PEMParser(new InputStreamReader(new ByteArrayInputStream(bOut.toByteArray())));
        d = (ContentInfo)pemRd.readObject();

        if (!d.getContentType().equals(CMSObjectIdentifiers.envelopedData))
            fail("failed envelopedData recode check");

        // OpenSSL test cases (as embedded resources)



        doDudPasswordTest("7fd98", 0, "corrupted stream - out of bounds length found");
        doDudPasswordTest("ef677", 1, "corrupted stream - out of bounds length found");
        doDudPasswordTest("800ce", 2, "unknown tag 26 encountered");
        doDudPasswordTest("b6cd8", 3, "DEF length 81 object truncated by 56");
        doDudPasswordTest("28ce09", 4, "DEF length 110 object truncated by 28");
        doDudPasswordTest("2ac3b9", 5, "DER length more than 4 bytes: 11");
        doDudPasswordTest("2cba96", 6, "DEF length 100 object truncated by 35");
        doDudPasswordTest("2e3354", 7, "DEF length 42 object truncated by 9");
        doDudPasswordTest("2f4142", 8, "DER length more than 4 bytes: 14");
        doDudPasswordTest("2fe9bb", 9, "DER length more than 4 bytes: 65");
        doDudPasswordTest("3ee7a8", 10, "DER length more than 4 bytes: 57");
        doDudPasswordTest("41af75", 11, "unknown tag 16 encountered");
        doDudPasswordTest("1704a5", 12, "corrupted stream detected");
        doDudPasswordTest("1c5822", 13, "unknown object in getInstance: org.bouncycastle.asn1.DERUTF8String");
        doDudPasswordTest("5a3d16", 14, "corrupted stream detected");
        doDudPasswordTest("8d0c97", 15, "corrupted stream detected");
        doDudPasswordTest("bc0daf", 16, "corrupted stream detected");
        doDudPasswordTest("aaf9c4d",17, "corrupted stream - out of bounds length found");


        // encrypted private key test
        InputDecryptorProvider pkcs8Prov = new JceOpenSSLPKCS8DecryptorProviderBuilder().build("password".toCharArray());
        pemRd = openPEMResource("enckey.pem");

        PKCS8EncryptedPrivateKeyInfo encPrivKeyInfo = (PKCS8EncryptedPrivateKeyInfo)pemRd.readObject();
        JcaPEMKeyConverter   converter = new JcaPEMKeyConverter().setProvider("BC");

        RSAPrivateCrtKey privKey = (RSAPrivateCrtKey)converter.getPrivateKey(encPrivKeyInfo.decryptPrivateKeyInfo(pkcs8Prov));

        if (!privKey.getPublicExponent().equals(new BigInteger("10001", 16)))
            fail("decryption of private key data check failed");

        // general PKCS8 test

        pemRd = openPEMResource("pkcs8test.pem");

        Object privInfo;

        while ((privInfo = pemRd.readObject()) != null)
            if (privInfo instanceof PrivateKeyInfo)
                privKey = (RSAPrivateCrtKey)converter.getPrivateKey(PrivateKeyInfo.getInstance(privInfo));
                privKey = (RSAPrivateCrtKey)converter.getPrivateKey(((PKCS8EncryptedPrivateKeyInfo)privInfo).decryptPrivateKeyInfo(pkcs8Prov));
            if (!privKey.getPublicExponent().equals(new BigInteger("10001", 16)))
                fail("decryption of private key data check failed");

    private void keyPairTest(
        String   name,
        KeyPair pair) 
        throws IOException
        PEMParser pemRd;
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        PEMWriter             pWrt = new PEMWriter(new OutputStreamWriter(bOut));



        pemRd = new PEMParser(new InputStreamReader(new ByteArrayInputStream(bOut.toByteArray())));

        SubjectPublicKeyInfo pub = SubjectPublicKeyInfo.getInstance(pemRd.readObject());
        JcaPEMKeyConverter   converter = new JcaPEMKeyConverter().setProvider("BC");

        PublicKey k = converter.getPublicKey(pub);

        if (!k.equals(pair.getPublic()))
            fail("Failed public key read: " + name);

        bOut = new ByteArrayOutputStream();
        pWrt = new PEMWriter(new OutputStreamWriter(bOut));



        pemRd = new PEMParser(new InputStreamReader(new ByteArrayInputStream(bOut.toByteArray())));

        KeyPair kPair = converter.getKeyPair((PEMKeyPair)pemRd.readObject());
        if (!kPair.getPrivate().equals(pair.getPrivate()))
            fail("Failed private key read: " + name);

        if (!kPair.getPublic().equals(pair.getPublic()))
            fail("Failed private key public read: " + name);

    private void doOpenSslTests(
        String baseName)
        throws IOException

    private void doOpenSslDsaModesTest(
        String baseName)
        throws IOException
        doOpenSslDsaTest(baseName + "_cbc");
        doOpenSslDsaTest(baseName + "_cfb");
        doOpenSslDsaTest(baseName + "_ecb");
        doOpenSslDsaTest(baseName + "_ofb");

    private void doOpenSslRsaModesTest(
        String baseName)
        throws IOException
        doOpenSslRsaTest(baseName + "_cbc");
        doOpenSslRsaTest(baseName + "_cfb");
        doOpenSslRsaTest(baseName + "_ecb");
        doOpenSslRsaTest(baseName + "_ofb");

    private void doOpenSslDsaTest(
        String name)
        throws IOException
        String fileName = "dsa/openssl_dsa_" + name + ".pem";

        doOpenSslTestFile(fileName, DSAPrivateKey.class);

    private void doOpenSslRsaTest(
        String name)
        throws IOException
        String fileName = "rsa/openssl_rsa_" + name + ".pem";

        doOpenSslTestFile(fileName, RSAPrivateKey.class);

    private void doOpenSslTestFile(
        String  fileName,
        Class   expectedPrivKeyClass)
        throws IOException
        JcaPEMKeyConverter   converter = new JcaPEMKeyConverter().setProvider("BC");
        PEMDecryptorProvider decProv = new JcePEMDecryptorProviderBuilder().setProvider("BC").build("changeit".toCharArray());
        PEMParser pr = openPEMResource("data/" + fileName);
        Object o = pr.readObject();

        if (o == null || !((o instanceof PEMKeyPair) || (o instanceof PEMEncryptedKeyPair)))
            fail("Didn't find OpenSSL key");

        KeyPair kp = (o instanceof PEMEncryptedKeyPair) ?
            converter.getKeyPair(((PEMEncryptedKeyPair)o).decryptKeyPair(decProv)) : converter.getKeyPair((PEMKeyPair)o);

        PrivateKey privKey = kp.getPrivate();

        if (!expectedPrivKeyClass.isInstance(privKey))
            fail("Returned key not of correct type");

    private void doDudPasswordTest(String password, int index, String message)
        // illegal state exception check - in this case the wrong password will
        // cause an underlying class cast exception.
            PEMDecryptorProvider decProv = new JcePEMDecryptorProviderBuilder().setProvider("BC").build(password.toCharArray());

            PEMParser pemRd = openPEMResource("test.pem");
            Object o;

            while ((o = pemRd.readObject()) != null)
                if (o instanceof PEMEncryptedKeyPair)

            fail("issue not detected: " + index);
        catch (IOException e)
            if (e.getCause() != null && !e.getCause().getMessage().endsWith(message))
               fail("issue " + index + " exception thrown, but wrong message");
            else if (e.getCause() == null && !e.getMessage().equals(message))
               fail("issue " + index + " exception thrown, but wrong message");

    private void doNoPasswordTest()
        throws IOException
        PEMDecryptorProvider decProv = new JcePEMDecryptorProviderBuilder().setProvider("BC").build("".toCharArray());

        PEMParser pemRd = openPEMResource("smimenopw.pem");
        Object o;
        PrivateKeyInfo key = null;

        while ((o = pemRd.readObject()) != null)
             key = (PrivateKeyInfo)o;

        if (key == null)
            fail("private key not detected");

    public static void main(
        String[]    args)
        Security.addProvider(new BouncyCastleProvider());

        runTest(new ParserTest());

Android WSDL/SOAP service client

private static  final  String NAMESPACE = "";
private static  final String URL = "";
private static  final  String SOAP_ACTION = "";
private static  final String METHOD_NAME = "Login";

//calling web services method

String loginresult=callService(username,password,usertype);

//calling webservices
String callService(String a1,String b1,Integer c1) throws Exception {

            Boolean flag=true;

                SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);

                PropertyInfo pa1 = new PropertyInfo();

                PropertyInfo pb1 = new PropertyInfo();

                PropertyInfo pc1 = new PropertyInfo();
                System.out.println(c1+"this is integer****s");


                SoapSerializationEnvelope envelope = new    SoapSerializationEnvelope(SoapEnvelope.VER11);
                envelope.dotNet = true;
                HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);
                androidHttpTransport.setXmlVersionTag("<?xml version=\"1.0\" encoding=\"utf-8\"?>");
      , envelope);
                catch(Exception e)

                    System.out.println(e+"   this is exception");
                SoapObject response = (SoapObject)envelope.bodyIn;

                result = response.getProperty(0).toString(); 

                }catch (Exception e) {
                // TODO: handle exception
            return result;


How do I apply the for-each loop to every character in a String?

You can also use a lambda in this case.

    String s = "xyz";
    IntStream.range(0, s.length()).forEach(i -> {
        char c = s.charAt(i);

OwinStartup not firing

I messed around with a lot of the suggestions on this post.

I had the following but still could not land on a break point. Throwing an exception proved the code was being entered.

  <add key="owin:AutomaticAppStartup" value="true" />
  <add key="owin:appStartup" value="SSOResource.Startup, SSOResource" />

Finally out of desperation I looked at project->properties, and then under the WEB section I also checked the NATIVE CODE checkbox (ASP.NET should be already checked).

That finally fixed it for me.

Note : I am using Visual Studio 2017 Professional.

How do I remove/delete a folder that is not empty?

Base on kkubasik's answer, check if folder exists before remove, more robust

import shutil
def remove_folder(path):
    # check if folder exists
    if os.path.exists(path):
         # remove if exists
         # throw your exception to handle this special scenario
         raise XXError("your exception") 

Alter table add multiple columns ms sql

Alter table Hotels 
 HasPhotoInReadyStorage  bit, 
 HasPhotoInWorkStorage  bit, 
 HasPhotoInMaterialStorage bit, 
 HasHotelPhotoInReadyStorage  bit, 
 HasHotelPhotoInWorkStorage  bit, 
 HasHotelPhotoInMaterialStorage bit, 
 HasReporterData  bit, 
 HasMovieInReadyStorage  bit, 
 HasMovieInWorkStorage  bit, 
 HasMovieInMaterialStorage bit 

Above you are using {, }.

Also, you are missing commas:

ADD ( HasPhotoInReadyStorage  bit, 
 HasPhotoInWorkStorage  bit, 
 HasPhotoInMaterialStorage bit <**** comma needed here
 HasText  bit); 

You need to remove the brackets and make sure all columns have a comma where necessary.

Difference between RegisterStartupScript and RegisterClientScriptBlock?

Here's an old discussion thread where I listed the main differences and the conditions in which you should use each of these methods. I think you may find it useful to go through the discussion.

To explain the differences as relevant to your posted example:

a. When you use RegisterStartupScript, it will render your script after all the elements in the page (right before the form's end tag). This enables the script to call or reference page elements without the possibility of it not finding them in the Page's DOM.

Here is the rendered source of the page when you invoke the RegisterStartupScript method:

<html xmlns="">
<head id="Head1"><title></title></head>
    <form name="form1" method="post" action="StartupScript.aspx" id="form1">
            <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="someViewstategibberish" />
        <div> <span id="lblDisplayDate">Label</span>
            <br />
            <input type="submit" name="btnPostback" value="Register Startup Script" id="btnPostback" />
            <br />
            <input type="submit" name="btnPostBack2" value="Register" id="btnPostBack2" />
            <input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="someViewstategibberish" />
        <!-- Note this part -->
        <script language='javascript'>
            var lbl = document.getElementById('lblDisplayDate');
   = 'red';
    <!-- Note this part -->

b. When you use RegisterClientScriptBlock, the script is rendered right after the Viewstate tag, but before any of the page elements. Since this is a direct script (not a function that can be called, it will immediately be executed by the browser. But the browser does not find the label in the Page's DOM at this stage and hence you should receive an "Object not found" error.

Here is the rendered source of the page when you invoke the RegisterClientScriptBlock method:

<html xmlns="">
<head id="Head1"><title></title></head>
    <form name="form1" method="post" action="StartupScript.aspx" id="form1">
            <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="someViewstategibberish" />
        <script language='javascript'>
            var lbl = document.getElementById('lblDisplayDate');
            // Error is thrown in the next line because lbl is null.
   = 'green';

Therefore, to summarize, you should call the latter method if you intend to render a function definition. You can then render the call to that function using the former method (or add a client side attribute).

Edit after comments:

For instance, the following function would work:

protected void btnPostBack2_Click(object sender, EventArgs e) 
  System.Text.StringBuilder sb = new System.Text.StringBuilder(); 
  sb.Append("<script language='javascript'>function ChangeColor() {"); 
  sb.Append("var lbl = document.getElementById('lblDisplayDate');"); 

  //Render the function definition. 
  if (!ClientScript.IsClientScriptBlockRegistered("JSScriptBlock")) 
    ClientScript.RegisterClientScriptBlock(this.GetType(), "JSScriptBlock", sb.ToString()); 

  //Render the function invocation. 
  string funcCall = "<script language='javascript'>ChangeColor();</script>"; 

  if (!ClientScript.IsStartupScriptRegistered("JSScript"))
    ClientScript.RegisterStartupScript(this.GetType(), "JSScript", funcCall); 

SQL Server - How to lock a table until a stored procedure finishes

Needed this answer myself and from the link provided by David Moye, decided on this and thought it might be of use to others with the same question:


  -- lock table "a" till end of transaction
  SELECT ...
  FROM a
  WHERE ...

  -- do some other stuff (including inserting/updating table "a")

  -- release lock

How can I make a weak protocol reference in 'pure' Swift (without @objc)

Apple uses "NSObjectProtocol" instead of "class".

public protocol UIScrollViewDelegate : NSObjectProtocol {

This also works for me and removed the errors I was seeing when trying to implement my own delegate pattern.

Get Selected value from Multi-Value Select Boxes by jquery-select2?

I know its late but I think you can try like this

$("#multipledpdwn").on("select2:select select2:unselect", function (e) {

    //this returns all the selected item
    var items= $(this).val();       

    //Gets the last selected item
    var lastSelectedItem =;


Hope it may help some one in future.

Export html table data to Excel using JavaScript / JQuery is not working properly in chrome browser

Simplest way using Jquery

Just add this:

<script src="[email protected]/dist/tableToExcel.js"></script>

Then add Jquery script:

<script type="text/javascript">
  $(document).ready(function () {
        TableToExcel.convert(document.getElementById("tab1"), {
            name: "Traceability.xlsx",
            sheet: {
            name: "Sheet1"

Then add HTML button:

<button id="exportBtn1">Export To Excel</button><br><br>

Note: "exportBtn1" will be button ID and "tab1" will be table ID

Javascript return number of days,hours,minutes,seconds between two dates

Use moment.js library, for example:

var time = date_future - date_now;
var seconds = moment.duration(time).seconds();
var minutes = moment.duration(time).minutes();
var hours   = moment.duration(time).hours();
var days    = moment.duration(time).days();

Convert AM/PM time to 24 hours format?

Convert a string to a DateTime, you could try

    DateTime timeValue = Convert.ToDateTime("01:00 PM");

How to validate domain credentials?

using System;
using System.Collections.Generic;
using System.Text;
using System.DirectoryServices.AccountManagement;

class WindowsCred
    private const string SPLIT_1 = "\\";

    public static bool ValidateW(string UserName, string Password)
        bool valid = false;
        string Domain = "";

        if (UserName.IndexOf("\\") != -1)
            string[] arrT = UserName.Split(SPLIT_1[0]);
            Domain = arrT[0];
            UserName = arrT[1];

        if (Domain.Length == 0)
            Domain = System.Environment.MachineName;

        using (PrincipalContext context = new PrincipalContext(ContextType.Domain, Domain)) 
            valid = context.ValidateCredentials(UserName, Password);

        return valid;

Kashif Mushtaq Ottawa, Canada how to deserialize without using the default constructor?

Based on some of the answers here, I have written a CustomConstructorResolver for use in a current project, and I thought it might help somebody else.

It supports the following resolution mechanisms, all configurable:

  • Select a single private constructor so you can define one private constructor without having to mark it with an attribute.
  • Select the most specific private constructor so you can have multiple overloads, still without having to use attributes.
  • Select the constructor marked with an attribute of a specific name - like the default resolver, but without a dependency on the Json.Net package because you need to reference Newtonsoft.Json.JsonConstructorAttribute.
public class CustomConstructorResolver : DefaultContractResolver
    public string ConstructorAttributeName { get; set; } = "JsonConstructorAttribute";
    public bool IgnoreAttributeConstructor { get; set; } = false;
    public bool IgnoreSinglePrivateConstructor { get; set; } = false;
    public bool IgnoreMostSpecificConstructor { get; set; } = false;

    protected override JsonObjectContract CreateObjectContract(Type objectType)
        var contract = base.CreateObjectContract(objectType);

        // Use default contract for non-object types.
        if (objectType.IsPrimitive || objectType.IsEnum) return contract;

        // Look for constructor with attribute first, then single private, then most specific.
        var overrideConstructor = 
               (this.IgnoreAttributeConstructor ? null : GetAttributeConstructor(objectType)) 
            ?? (this.IgnoreSinglePrivateConstructor ? null : GetSinglePrivateConstructor(objectType)) 
            ?? (this.IgnoreMostSpecificConstructor ? null : GetMostSpecificConstructor(objectType));

        // Set override constructor if found, otherwise use default contract.
        if (overrideConstructor != null)
            SetOverrideCreator(contract, overrideConstructor);

        return contract;

    private void SetOverrideCreator(JsonObjectContract contract, ConstructorInfo attributeConstructor)
        contract.OverrideCreator = CreateParameterizedConstructor(attributeConstructor);
        foreach (var constructorParameter in base.CreateConstructorParameters(attributeConstructor, contract.Properties))

    private ObjectConstructor<object> CreateParameterizedConstructor(MethodBase method)
        var c = method as ConstructorInfo;
        if (c != null)
            return a => c.Invoke(a);
        return a => method.Invoke(null, a);

    protected virtual ConstructorInfo GetAttributeConstructor(Type objectType)
        var constructors = objectType
            .GetConstructors(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
            .Where(c => c.GetCustomAttributes().Any(a => a.GetType().Name == this.ConstructorAttributeName)).ToList();

        if (constructors.Count == 1) return constructors[0];
        if (constructors.Count > 1)
            throw new JsonException($"Multiple constructors with a {this.ConstructorAttributeName}.");

        return null;

    protected virtual ConstructorInfo GetSinglePrivateConstructor(Type objectType)
        var constructors = objectType
            .GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic);

        return constructors.Length == 1 ? constructors[0] : null;

    protected virtual ConstructorInfo GetMostSpecificConstructor(Type objectType)
        var constructors = objectType
            .GetConstructors(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
            .OrderBy(e => e.GetParameters().Length);

        var mostSpecific = constructors.LastOrDefault();
        return mostSpecific;

Here is the complete version with XML documentation as a gist:

Feedback appreciated.

Multiple inheritance for an anonymous class

Anonymous classes must extend or implement something, like any other Java class, even if it's just java.lang.Object.

For example:

Runnable r = new Runnable() {
   public void run() { ... }

Here, r is an object of an anonymous class which implements Runnable.

An anonymous class can extend another class using the same syntax:

SomeClass x = new SomeClass() {

What you can't do is implement more than one interface. You need a named class to do that. Neither an anonymous inner class, nor a named class, however, can extend more than one class.

Checking if my Windows application is running

you can simply use varialbles and one file to check for running your program. when open the file contain a value and when program closes changes this value to another one.

bootstrap popover not showing on top of all elements

The most probable cause is that the content displaying over the popover has a higher z-index. Without the precise code/style, I can offer two options :

You should try pinpointing the exact elements with a web inspector (usually F12 on your favorite browser) and check their actual z-index.

If you find this value, you can set it lower than the popover which is z-index: 1010; by default

Or the other approach, not as good, would be to increase the z-index of the popover. You can do that either with the @zindexPopover in the Less files or directly by overriding

.popover {
    z-index: 1010; /* A value higher than 1010 that solves the problem */

If you can't find a solution, you should try reproducing the bug in something like this jsfiddle - you will probably resolve the problem while trying to get the bug.

change text of button and disable button in iOS

SWIFT 4 with extension


// set button label for all states
extension UIButton {
    public func setAllStatesTitle(_ newTitle: String){
        self.setTitle(newTitle, for: .normal)
        self.setTitle(newTitle, for: .selected)
        self.setTitle(newTitle, for: .disabled)

and use:

yourBtn.setAllStatesTitle("btn title")

Programmatically Add CenterX/CenterY Constraints

Programmatically you can do it by adding the following constraints.

NSLayoutConstraint *constraintHorizontal = [NSLayoutConstraint constraintWithItem:self  

NSLayoutConstraint *constraintVertical = [NSLayoutConstraint constraintWithItem:self

How to delete an element from an array in C#

Removing from an array itself is not simple, as you then have to deal with resizing. This is one of the great advantages of using something like a List<int> instead. It provides Remove/RemoveAt in 2.0, and lots of LINQ extensions for 3.0.

If you can, refactor to use a List<> or similar.

get data from mysql database to use in javascript

To do with javascript you could do something like this:

<script type="Text/javascript">
var text = <?= $text_from_db; ?>

Then you can use whatever you want in your javascript to put the text var into the textbox.

CUSTOM_ELEMENTS_SCHEMA added to NgModule.schemas still showing Error

I'd like to add one additional piece of information since the accepted answer above didn't fix my errors completely.

In my scenario, I have a parent component, which holds a child component. And that child component also contains another component.

So, my parent component's spec file need to have the declaration of the child component, AS WELL AS THE CHILD'S CHILD COMPONENT. That finally fixed the issue for me.

Change the Bootstrap Modal effect

    display: block;_x000D_
.custom-modal .modal-content_x000D_
    border: none;_x000D_
    display: block !important;_x000D_
.custom-fade .modal-dialog {_x000D_
    transform: translateY(4%);_x000D_
    opacity: 0;_x000D_
    -webkit-transition: all .2s ease-out;_x000D_
    -o-transition: all .2s ease-out;_x000D_
    transition: all .2s ease-out;_x000D_
    will-change: transform;_x000D_
}_x000D_ .modal-dialog  {_x000D_
    opacity: 1;_x000D_
    transform: translateY(0%);_x000D_
<div class="modal custom-modal custom-fade" tabindex="-1" role="dialog"_x000D_
    <div class="modal-dialog modal-lg">_x000D_
        <div class="modal-content">_x000D_
            <div class="modal-header">_x000D_
                <h5 class="modal-title">Title</h5>_x000D_
            <div class="modal-body">_x000D_
                <p>My cat is dope.</p>_x000D_
            <div class="modal-footer">_x000D_
                <button type="button" class="btn btn-primary" data-dismiss="modal">Sure (Meow)</button>_x000D_

How do I compare two strings in python?

If you just need to check if the two strings are exactly same,

text1 = 'apple'

text2 = 'apple'

text1 == text2

The result will be


If you need the matching percentage,

import difflib

text1 = 'Since 1958.'

text2 = 'Since 1958'

output = str(int(difflib.SequenceMatcher(None, text1, text2).ratio()*100))

Matching percentage output will be,


How to stop VBA code running?

I do this a lot. A lot. :-)

I have got used to using "DoEvents" more often, but still tend to set things running without really double checking a sure stop method.

Then, today, having done it again, I thought, "Well just wait for the end in 3 hours", and started paddling around in the ribbon. Earlier, I had noticed in the "View" section of the Ribbon a "Macros" pull down, and thought I have a look to see if I could see my interminable Macro running....

I now realise you can also get this up using Alt-F8.

Then I thought, well what if I "Step into" a different Macro, would that rescue me? It did :-) It also works if you step into your running Macro (but you still lose where you're upto), unless you are a very lazy programmer like me and declare lots of "Global" variables, in which case the Global data is retained :-)


Is Java's assertEquals method reliable?

The JUnit assertEquals(obj1, obj2) does indeed call obj1.equals(obj2).

There's also assertSame(obj1, obj2) which does obj1 == obj2 (i.e., verifies that obj1 and obj2 are referencing the same instance), which is what you're trying to avoid.

So you're fine.

How to round up a number in Javascript?

Normal rounding will work with a small tweak:

Math.round(price * 10)/10

and if you want to keep a currency format, you can use the Number method .toFixed()

(Math.round(price * 10)/10).toFixed(2)

Though this will make it a String =)

Escaping regex string

Please give a try:

\Q and \E as anchors

Put an Or condition to match either a full word or regex.

Ref Link : How to match a whole word that includes special characters in regex

Java SSLHandshakeException "no cipher suites in common"

This problem can be caused by undue manipulation of the enabled cipher suites at the client or the server, but I suspect the most common cause is the server not having a private key and certificate at all.



Get rid of this line. Your server is insecure enough already with that insecure TrustManager. Then run your server with,handshake, try one connect, and post the resulting output here.

Blank HTML SELECT without blank item in dropdown list

For purely html @isherwood has a great solution. For jQuery, give your select drop down an ID then select it with jQuery:

  <select id="myDropDown">
    <option value="0">aaaa</option>
    <option value="1">bbbb</option>

Then use this jQuery to clear the drop down on page load:

$(document).ready(function() {

Or put it inside a function by itself:


accomplishes what you're looking for and it is easy to put this in functions that may get called on your page if you need to blank out the drop down without reloading the page.

CSS filter: make color image with transparency white

To my knowledge, there is sadly no CSS filter to colorise an element (perhaps with the use of some SVG filter magic, but I'm somewhat unfamiliar with that) and even if that wasn't the case, filters are basically only supported by webkit browsers.

With that said, you could still work around this and use a canvas to modify your image. Basically, you can draw an image element onto a canvas and then loop through the pixels, modifying the respective RGBA values to the colour you want.

However, canvases do come with some restrictions. Most importantly, you have to make sure that the image src comes from the same domain as the page. Otherwise the browser won't allow you to read or modify the pixel data of the canvas.

Here's a JSFiddle changing the colour of the JSFiddle logo.

//Base64 source, but any local source will work_x000D_
var src = "data:image/png;base64,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";_x000D_
var canvas = document.getElementById("theCanvas");_x000D_
var ctx = canvas.getContext("2d");_x000D_
var img = new Image;_x000D_
//wait for the image to load_x000D_
img.onload = function() {_x000D_
    //Draw the original image so that you can fetch the colour data_x000D_
    var imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);_x000D_
    /*_x000D_ is a one-dimensional array which contains _x000D_
    the respective RGBA values for every pixel _x000D_
    in the selected region of the context _x000D_
    (note i+=4 in the loop)_x000D_
    for (var i = 0; i <; i+=4) {_x000D_[i] = 255; //Red, 0-255_x000D_[i+1] = 255; //Green, 0-255_x000D_[i+2] = 255; //Blue, 0-255_x000D_
   /* _x000D_[i+3] contains the alpha value_x000D_
   which we are going to ignore and leave_x000D_
   alone with its original value_x000D_
    ctx.clearRect(0, 0, canvas.width, canvas.height); //clear the original image_x000D_
    ctx.putImageData(imgData, 0, 0); //paint the new colorised image_x000D_
//Load the image!_x000D_
img.src = src;
body {_x000D_
    background: green;_x000D_
<canvas id="theCanvas"></canvas>

Search and replace a particular string in a file using Perl

You could also do this:


use strict;
use warnings;

$^I = '.bak'; # create a backup copy 

while (<>) {
   s/<PREF>/ABCD/g; # do the replacement
   print; # print to the modified file

Invoke the script with by

./ input_file

You will get a file named input_file, containing your changes, and a file named input_file.bak, which is simply a copy of the original file.

Why is SQL server throwing this error: Cannot insert the value NULL into column 'id'?

if use entityframework. open migration, set value nullable: true, and update database

enter image description here

Reading a string with spaces with sscanf

I guess this is what you want, it does exactly what you specified.


int main(int argc, char** argv) {
    int age;
    char* buffer;
    buffer = malloc(200 * sizeof(char));
    sscanf("19 cool kid", "%d cool %s", &age, buffer);
    printf("cool %s is %d years old\n", buffer, age);
    return 0;

The format expects: first a number (and puts it at where &age points to), then whitespace (zero or more), then the literal string "cool", then whitespace (zero or more) again, and then finally a string (and put that at whatever buffer points to). You forgot the "cool" part in your format string, so the format then just assumes that is the string you were wanting to assign to buffer. But you don't want to assign that string, only skip it.

Alternative, you could also have a format string like: "%d %s %s", but then you must assign another buffer for it (with a different name), and print it as: "%s %s is %d years old\n".

JavaScript get window X/Y position for scroll

Using pure javascript you can use Window.scrollX and Window.scrollY

window.addEventListener("scroll", function(event) {
    var top = this.scrollY,
        left =this.scrollX;
}, false);


The pageXOffset property is an alias for the scrollX property, and The pageYOffset property is an alias for the scrollY property:

window.pageXOffset == window.scrollX; // always true
window.pageYOffset == window.scrollY; // always true

Here is a quick demo

window.addEventListener("scroll", function(event) {_x000D_
    var top = this.scrollY,_x000D_
        left = this.scrollX;_x000D_
    var horizontalScroll = document.querySelector(".horizontalScroll"),_x000D_
        verticalScroll = document.querySelector(".verticalScroll");_x000D_
    horizontalScroll.innerHTML = "Scroll X: " + left + "px";_x000D_
      verticalScroll.innerHTML = "Scroll Y: " + top + "px";_x000D_
}, false);
*{box-sizing: border-box}_x000D_
:root{height: 200vh;width: 200vw}_x000D_
    position: fixed;_x000D_
    background: black;_x000D_
    color: green;_x000D_
    height: 64px;_x000D_
.wrapper div{_x000D_
    display: inline;_x000D_
    width: 50%;_x000D_
    float: left;_x000D_
    text-align: center;_x000D_
    line-height: 64px_x000D_
.horizontalScroll{color: orange}
<div class=wrapper>_x000D_
    <div class=horizontalScroll>Scroll (x,y) to </div>_x000D_
    <div class=verticalScroll>see me in action</div>_x000D_

Read a variable in bash with a default value

I found this question, looking for a way to present something like:

Something interesting happened.  Proceed [Y/n/q]:

Using the above examples I deduced this:-

echo -n "Something interesting happened.  "
read -e -p "Proceed [Y/n/q]:" PROCEED
# adopt the default, if 'enter' given
# change to lower case to simplify following if
# condition for specific letter
if [ "${PROCEED}" == "q" ] ; then
  echo "Quitting"
# condition for non specific letter (ie anything other than q/y)
# if you want to have the active 'y' code in the last section
elif [ "${PROCEED}" != "y" ] ; then
  echo "Not Proceeding"
  echo "Proceeding"
  # do proceeding code in here

Hope that helps someone to not have to think out the logic, if they encounter the same problem

How to represent the double quotes character (") in regex?

Firstly, double quote character is nothing special in regex - it's just another character, so it doesn't need escaping from the perspective of regex.

However, because java uses double quotes to delimit String constants, if you want to create a string in java with a double quote in it, you must escape them.

This code will test if your String matches:

if (str.matches("\".*\"")) {
    // this string starts and end with a double quote

Note that you don't need to add start and end of input markers (^ and $) in the regex, because matches() requires that the whole input be matched to return true - ^ and $ are implied.

string in namespace std does not name a type

You need to add:

#include <string>

In your header file.

visual c++: #include files from other projects in the same solution

Settings for compiler

In the project where you want to #include the header file from another project, you will need to add the path of the header file into the Additional Include Directories section in the project configuration.

To access the project configuration:

  1. Right-click on the project, and select Properties.
  2. Select Configuration Properties->C/C++->General.
  3. Set the path under Additional Include Directories.

How to include

To include the header file, simply write the following in your code:

#include "filename.h"

Note that you don't need to specify the path here, because you include the directory in the Additional Include Directories already, so Visual Studio will know where to look for it.

If you don't want to add every header file location in the project settings, you could just include a directory up to a point, and then #include relative to that point:

// In project settings
Additional Include Directories    ..\..\libroot

// In code
#include "lib1/lib1.h"    // path is relative to libroot
#include "lib2/lib2.h"    // path is relative to libroot

Setting for linker

If using static libraries (i.e. .lib file), you will also need to add the library to the linker input, so that at linkage time the symbols can be linked against (otherwise you'll get an unresolved symbol):

  1. Right-click on the project, and select Properties.
  2. Select Configuration Properties->Linker->Input
  3. Enter the library under Additional Dependencies.

Is there an opposite to display:none?

opposite of 'none' is 'flex' while working with react native.

prevent refresh of page when button inside form clicked

You can use ajax and jquery to solve this problem:

    function getData() {
            url : "/urlpattern",
            type : "post",
            success : function(data) {
<form method="POST">
    <button name="data" type="button" onclick="getData()">Click</button>

Separation of business logic and data access in django

An old question, but I'd like to offer my solution anyway. It's based on acceptance that model objects too require some additional functionality while it's awkward to place it within the Heavy business logic may be written separately depending on personal taste, but I at least like the model to do everything related to itself. This solution also supports those who like to have all the logic placed within models themselves.

As such, I devised a hack that allows me to separate logic from model definitions and still get all the hinting from my IDE.

The advantages should be obvious, but this lists a few that I have observed:

  • DB definitions remain just that - no logic "garbage" attached
  • Model-related logic is all placed neatly in one place
  • All the services (forms, REST, views) have a single access point to logic
  • Best of all: I did not have to rewrite any code once I realised that my became too cluttered and had to separate the logic away. The separation is smooth and iterative: I could do a function at a time or entire class or the entire

I have been using this with Python 3.4 and greater and Django 1.8 and greater.


from app.logic.user import UserLogic

class User(models.Model, UserLogic):
    field1 = models.AnyField(....)
    ... field definitions ...


if False:
    # This allows the IDE to know about the User model and its member fields
    from main.models import User

class UserLogic(object):
    def logic_function(self: 'User'):
        ... code with hinting working normally ...

The only thing I can't figure out is how to make my IDE (PyCharm in this case) recognise that UserLogic is actually User model. But since this is obviously a hack, I'm quite happy to accept the little nuisance of always specifying type for self parameter.

How to use onResume()?


Any Activity that restarts has its onResume() method executed first.

To use this method, do this:

override fun onResume() {
        // your code here

Credit card payment gateway in PHP?

Braintree also has an open source PHP library that makes PHP integration pretty easy.

convert epoch time to date

Here’s the modern answer (valid from 2014 and on). The accepted answer was a very fine answer in 2011. These days I recommend no one uses the Date, DateFormat and SimpleDateFormat classes. It all goes more natural with the modern Java date and time API.

To get a date-time object from your millis:

    ZonedDateTime dateTime = Instant.ofEpochMilli(millis)

If millis equals 1318388699000L, this gives you 2011-10-12T14:04:59+11:00[Australia/Sydney]. Should the code in some strange way end up on a JVM that doesn’t know Australia/Sydney time zone, you can be sure to be notified through an exception.

If you want the date-time in your string format for presentation:

String formatted = dateTime.format(DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss"));


12/10/2011 14:04:59

PS I don’t know what you mean by “The above doesn't work.” On my computer your code in the question too prints 12/10/2011 14:04:59.

Which JRE am I using?

The following command will tell you a lot of information about your java version, including the vendor:

java -XshowSettings:properties -version

It works on Windows, Mac, and Linux.

How do I add an "Add to Favorites" button or link on my website?

  if (window.sidebar) { // Mozilla Firefox Bookmark

It adds the bookmark but in the sidebar.

Onchange open URL via select - jQuery

If you don't want the url to put it on option's value, i'll give u example :

<select class="abc">
    <option value="0" href="hello">Hell</option>
    <option value="1" href="dello">Dell</option>
    <option value="2" href="cello">Cell</option>


How can I read inputs as numbers?

Multiple questions require input for several integers on single line. The best way is to input the whole string of numbers one one line and then split them to integers. Here is a Python 3 version:

a = []
p = input()
p = p.split()      
for i in p:

Also a list comprehension can be used

p = input().split("whatever the seperator is")

And to convert all the inputs from string to int we do the following

x = [int(i) for i in p]
print(x, end=' ')

shall print the list elements in a straight line.

Example for boost shared_mutex (multiple reads/one write)?

It looks like you would do something like this:

boost::shared_mutex _access;
void reader()
  // get shared access
  boost::shared_lock<boost::shared_mutex> lock(_access);

  // now we have shared access

void writer()
  // get upgradable access
  boost::upgrade_lock<boost::shared_mutex> lock(_access);

  // get exclusive access
  boost::upgrade_to_unique_lock<boost::shared_mutex> uniqueLock(lock);
  // now we have exclusive access

Transport endpoint is not connected

So interestingly enough this error "Transport endpoint is not connected" was caused by my having more than one Veracrypt device mounted. I closed the extra device and suddenly I had access to the drive. Hmm..

Correctly Parsing JSON in Swift 3

First of all never load data synchronously from a remote URL, use always asynchronous methods like URLSession.

'Any' has no subscript members

occurs because the compiler has no idea of what type the intermediate objects are (for example currently in ["currently"]!["temperature"]) and since you are using Foundation collection types like NSDictionary the compiler has no idea at all about the type.

Additionally in Swift 3 it's required to inform the compiler about the type of all subscripted objects.

You have to cast the result of the JSON serialization to the actual type.

This code uses URLSession and exclusively Swift native types

let urlString = ",122.048951"

let url = URL(string: urlString)
URLSession.shared.dataTask(with:url!) { (data, response, error) in
  if error != nil {
  } else {
    do {

      let parsedData = try JSONSerialization.jsonObject(with: data!) as! [String:Any]
      let currentConditions = parsedData["currently"] as! [String:Any]


      let currentTemperatureF = currentConditions["temperature"] as! Double
    } catch let error as NSError {


To print all key / value pairs of currentConditions you could write

 let currentConditions = parsedData["currently"] as! [String:Any]

  for (key, value) in currentConditions {
    print("\(key) - \(value) ")

A note regarding jsonObject(with data:

Many (it seems all) tutorials suggest .mutableContainers or .mutableLeaves options which is completely nonsense in Swift. The two options are legacy Objective-C options to assign the result to NSMutable... objects. In Swift any variable is mutable by default and passing any of those options and assigning the result to a let constant has no effect at all. Further most of the implementations are never mutating the deserialized JSON anyway.

The only (rare) option which is useful in Swift is .allowFragments which is required if if the JSON root object could be a value type(String, Number, Bool or null) rather than one of the collection types (array or dictionary). But normally omit the options parameter which means No options.


Some general considerations to parse JSON

JSON is a well-arranged text format. It's very easy to read a JSON string. Read the string carefully. There are only six different types – two collection types and four value types.

The collection types are

  • Array - JSON: objects in square brackets [] - Swift: [Any] but in most cases [[String:Any]]
  • Dictionary - JSON: objects in curly braces {} - Swift: [String:Any]

The value types are

  • String - JSON: any value in double quotes "Foo", even "123"or "false" – Swift: String
  • Number - JSON: numeric values not in double quotes 123 or 123.0 – Swift: Int or Double
  • Bool - JSON: true or false not in double quotes – Swift: true or false
  • null - JSON: null – Swift: NSNull

According to the JSON specification all keys in dictionaries are required to be String.

Basically it's always recommeded to use optional bindings to unwrap optionals safely

If the root object is a dictionary ({}) cast the type to [String:Any]

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [String:Any] { ...

and retrieve values by keys with (OneOfSupportedJSONTypes is either JSON collection or value type as described above.)

if let foo = parsedData["foo"] as? OneOfSupportedJSONTypes {

If the root object is an array ([]) cast the type to [[String:Any]]

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]] { ...

and iterate through the array with

for item in parsedData {

If you need an item at specific index check also if the index exists

if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]], parsedData.count > 2,
   let item = parsedData[2] as? OneOfSupportedJSONTypes {

In the rare case that the JSON is simply one of the value types – rather than a collection type – you have to pass the .allowFragments option and cast the result to the appropriate value type for example

if let parsedData = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? String { ...

Apple has published a comprehensive article in the Swift Blog: Working with JSON in Swift


In Swift 4+ the Codable protocol provides a more convenient way to parse JSON directly into structs / classes.

For example the given JSON sample in the question (slightly modified)

let jsonString = """
{"icon": "partly-cloudy-night", "precipProbability": 0, "pressure": 1015.39, "humidity": 0.75, "precip_intensity": 0, "wind_speed": 6.04, "summary": "Partly Cloudy", "ozone": 321.13, "temperature": 49.45, "dew_point": 41.75, "apparent_temperature": 47, "wind_bearing": 332, "cloud_cover": 0.28, "time": 1480846460}

can be decoded into the struct Weather. The Swift types are the same as described above. There are a few additional options:

  • Strings representing an URL can be decoded directly as URL.
  • The time integer can be decoded as Date with the dateDecodingStrategy .secondsSince1970.
  • snaked_cased JSON keys can be converted to camelCase with the keyDecodingStrategy .convertFromSnakeCase

struct Weather: Decodable {
    let icon, summary: String
    let pressure: Double, humidity, windSpeed : Double
    let ozone, temperature, dewPoint, cloudCover: Double
    let precipProbability, precipIntensity, apparentTemperature, windBearing : Int
    let time: Date

let data = Data(jsonString.utf8)
do {
    let decoder = JSONDecoder()
    decoder.dateDecodingStrategy = .secondsSince1970
    decoder.keyDecodingStrategy = .convertFromSnakeCase
    let result = try decoder.decode(Weather.self, from: data)
} catch {

Other Codable sources:

How to host material icons offline?

With angular cli

npm install angular-material-icons --save


npm install material-design-icons-iconfont --save

material-design-icons-iconfont is the latest updated version of the icons. angular-material-icons is not updated for a long time

Wait wait wait install to be done and then add it to angular.json -> projects -> architect -> styles

 "styles": [

or if you installed material-desing-icons-iconfont then

"styles": [

Jenkins / Hudson environment variables

1- add to your profil file".bash_profile" file

it is in "/home/your_user/" folder

vi .bash_profile


export JENKINS_HOME=/apps/data/jenkins  

==> it's the e jenkins workspace

2- If you use jetty : go to jenkins.xml file

and add :


Change Oracle port from port 8080

I assume you're talking about the Apache server that Oracle installs. Look for the file httpd.conf.

Open this file in a text editor and look for the line
Listen 8080
Listen {ip address}:8080

Change the port number and either restart the web server or just reboot the machine.

Force add despite the .gitignore file

See man git-add:

   -f, --force
       Allow adding otherwise ignored files.

So run this

git add --force my/ignore/

ActiveXObject is not defined and can't find variable: ActiveXObject

ActiveXObject is available only on IE browser. So every other useragent will throw an error

On modern browser you could use instead File API or File writer API (currently implemented only on Chrome)

How to create own dynamic type or dynamic object in C#?

You can use ExpandoObject Class which is in System.Dynamic namespace.

dynamic MyDynamic = new ExpandoObject();
MyDynamic.A = "A";
MyDynamic.B = "B";
MyDynamic.C = "C";
MyDynamic.SomeProperty = SomeValue
MyDynamic.number = 10;
MyDynamic.Increment = (Action)(() => { MyDynamic.number++; });

More Info can be found at ExpandoObject MSDN

The following classes could not be instantiated: -

Find styles.xml in app/res/values folder.

Parent attribute of the style could be missing "Base". It should start as

<style name="AppTheme" parent="Base.Theme.AppCompat...

Check whether a variable is a string in Ruby

In addition to the other answers, Class defines the method === to test whether an object is an instance of that class.

  • o.class class of o.
  • o.instance_of? c determines whether o.class == c
  • o.is_a? c Is o an instance of c or any of it's subclasses?
  • o.kind_of? c synonym for *is_a?*
  • c === o for a class or module, determine if *o.is_a? c* (String === "s" returns true)

AttributeError: can't set attribute in python

For those searching this error, another thing that can trigger AtributeError: can't set attribute is if you try to set a decorated @property that has no setter method. Not the problem in the OP's question, but I'm putting it here to help any searching for the error message directly. (if you don't like it, go edit the question's title :)

class Test:
    def __init__(self):
        self._attr = "original value"
        # This will trigger an error...
        self.attr = "new value"
    def attr(self):
        return self._attr


What's in an Eclipse .classpath/.project file?

Complete reference is not available for the mentioned files, as they are extensible by various plug-ins.

Basically, .project files store project-settings, such as builder and project nature settings, while .classpath files define the classpath to use during running. The classpath files contains src and target entries that correspond with folders in the project; the con entries are used to describe some kind of "virtual" entries, such as the JVM libs or in case of eclipse plug-ins dependencies (normal Java project dependencies are displayed differently, using a special src entry).

What is Inversion of Control?

Creating an object within class is called tight coupling, Spring removes this dependency by following a design pattern(DI/IOC). In which object of class in passed in constructor rather than creating in class. More over we give super class reference variable in constructor to define more general structure.

How to navigate through a vector using iterators? (C++)

You need to make use of the begin and end method of the vector class, which return the iterator referring to the first and the last element respectively.

using namespace std;  

vector<string> myvector;  // a vector of stings.

// push some strings in the vector.

vector<string>::iterator it;  // declare an iterator to a vector of strings
int n = 3;  // nth element to be found.
int i = 0;  // counter.

// now start at from the beginning
// and keep iterating over the element till you find
// nth element...or reach the end of vector.
for(it = myvector.begin(); it != myvector.end(); it++,i++ )    {
    // found nth element..print and break.
    if(i == n) {
        cout<< *it << endl;  // prints d.

// other easier ways of doing the same.
// using operator[]
cout<<myvector[n]<<endl;  // prints d.

// using the at method
cout << << endl;  // prints d.

ios app maximum memory budget

You should watch session 147 from the WWDC 2010 Session videos. It is "Advanced Performance Optimization on iPhone OS, part 2".
There is a lot of good advice on memory optimizations.

Some of the tips are:

  • Use nested NSAutoReleasePools to make sure your memory usage does not spike.
  • Use CGImageSource when creating thumbnails from large images.
  • Respond to low memory warnings.

Java: Local variable mi defined in an enclosing scope must be final or effectively final

One solution is to create a named class instead of using an anonymous class. Give that named class a constructor that takes whatever parameters you wish and assigns them to class fields:

class MenuActionListener implements ActionListener {
    private Color kolorIkony;

    public MenuActionListener(Color kolorIkony) {
        this.kolorIkony = kolorIkony

    public void actionPerformed(ActionEvent e) {
        JMenuItem item = (JMenuItem) e.getSource();
        IconA icon = (IconA) item.getIcon();
        // Use the class field here

Now you can create an instance of this class as usual:

Jmi.addActionListener(new MenuActionListener(getColor(colors[mi]));

Fatal error: [] operator not supported for strings

Such behavior is described in Migrating from PHP 7.0.x to PHP 7.1.x/

The empty index operator is not supported for strings anymore Applying the empty index operator to a string (e.g. $str[] = $x) throws a fatal error instead of converting silently to array.

In my case it was a mere initialization. I fixed it by replacing $foo='' with $foo=[].


How to change button text in Swift Xcode 6?



someButton.setTitle("New Title", forState: .normal)

works only when Title type is Plain.

enter image description here

Quickest way to convert XML to JSON in Java

To convert XML File in to JSON include the following dependency


and you can Download Jar from Maven Repository here. Then implement as:

String soapmessageString = "<xml>yourStringURLorFILE</xml>";
JSONObject soapDatainJsonObject = XML.toJSONObject(soapmessageString);

Design Android EditText to show error message as described by google

If anybody still facing the error with using google's design library as mentioned in the answer then, please use this as commented by @h_k which is -

Instead of calling setError on TextInputLayout, You might be using setError on EditText itself.

Cannot convert lambda expression to type 'string' because it is not a delegate type

My case it solved i was using

@Html.DropDownList(model => model.TypeId ...)  


@Html.DropDownListFor(model => model.TypeId ...) 

will solve it

Difference between null and empty string

When Object variables are initially used in a language like Java, they have absolutely no value at all - not zero, but literally no value - that is null

For instance: String s;

If you were to use s, it would actually have a value of null, because it holds absolute nothing.

An empty string, however, is a value - it is a string of no characters.

String s; //Inits to null
String a =""; //A blank string

Null is essentially 'nothing' - it's the default 'value' (to use the term loosely) that Java assigns to any Object variable that was not initialized.

Null isn't really a value - and as such, doesn't have properties. So, calling anything that is meant to return a value - such as .length(), will invariably return an error, because 'nothing' cannot have properties.

To go into more depth, by creating s1 = ""; you are initializing an object, which can have properties, and takes up relevant space in memory. By using s2; you are designating that variable name to be a String, but are not actually assigning any value at that point.

Detecting IE11 using CSS Capability/Feature Detection

Step back: why are you even trying to detect "internet explorer" rather than "my website needs to do X, does this browser support that feature? If so, good browser. If not, then I should warn the user".

You should hit up instead of continuing what you're doing.

Handling click events on a drawable within an EditText

Better to have ImageButton on Right of edit text and give negative layout margin to overlap with edit text. Set listener on ImageButton and perform operations.

Microsoft Excel mangles Diacritics in .csv files?

select UTF-8 enconding when importing. if you use Office 2007 this is where you chose it : right after you open the file.

Mocking Logger and LoggerFactory with PowerMock and Mockito

I think you can reset the invocations using Mockito.reset(mockLog). You should call this before every test, so inside @Before would be a good place.

How to programmatically determine the current checked out Git branch

That's one solution. If you add it to your .bashrc, it'll display the current branch in the console.

# git branch
parse_git_branch() {
    git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/(\1) /'

However it's pretty limited. But there is a great project called git sh, which is doing exactly that (and much more).

Download TS files from video stream

---> Open Firefox

---> open page the video

---> Play Video

Click ---> Open menu

Click ---> open web developer tools

Click ---> Developer Toolbar

Click ---> Network

---> Go to Filter URLs ---> Write "M3u8" --> for Find "m3u8"

---> Copy URL ".m3u8"


Now Download software "m3u8x" ---->

---> open software "m3u8x"

---> paste URL "m3u8"

---> chose option "One...One"

---> Click Download

---> Start Download


image "Open menu" ===>

a busy cat

image "Developer Toolbar" ===>

a busy cat

image "m3u8x" ===>

enter image description here

enter image description here

How to create a sticky footer that plays well with Bootstrap 3

In case your html has the (rough) structure:

<div class="wrapper">
<div class="footer">

then the simplest css that fixes footer to the bottom of your screen is

html, body {
    height: 100%;
.wrapper {
  min-height: calc(100vh - 80px);
.footer {
   height: 80px;

... where the height of the footer is 80px. calc calculates the height of the wrapper to be equal to the window's height minus the height of the footer (80px) which is out of the .wrapper

How to get anchor text/href on click using jQuery?

Updated code

  var currentAnchor = $(this);

Close Current Tab

Found a one-liner that works in Chrome 66 from:

TLDR: tricks the browser into believing JavaScirpt opened the current tab/window'', '_parent', '').close();

So for completeness

<input type="button" name="close" value="close" onclick="window.close();">

Though let it also be noted that readers may want to place this into a function that fingerprints which browsers require such trickery, because Firefox 59 doesn't work with the above.

<embed> vs. <object>

OBJECT vs. EMBED - why not always use embed?

Bottom line: OBJECT is Good, EMBED is Old. Beside's IE's PARAM tags, any content between OBJECT tags will get rendered if the browser doesn't support OBJECT's referred plugin, and apparently, the content gets http requested regardless if it gets rendered or not.

object is the current standard tag to embed something on a page. embed was included by Netscape (along img) before anything like object were on the w3c mind.

This is how you include a PDF with object:

<object data="data/test.pdf" type="application/pdf" width="300" height="200">
  alt : <a href="data/test.pdf">test.pdf</a>

If you really need the inline PDF to show in almost every browser, as older browsers understand embed but not object, you'll need to do this:

<object data="abc.pdf" type="application/pdf">
    <embed src="abc.pdf" type="application/pdf" />

This version does not validate.

How to force remounting on React components?

I'm working on Crud for my app. This is how I did it Got Reactstrap as my dependency.

import React, { useState, setState } from 'react';
import 'bootstrap/dist/css/bootstrap.min.css';
import firebase from 'firebase';
// import { LifeCrud } from '../CRUD/Crud';
import { Row, Card, Col, Button } from 'reactstrap';
import InsuranceActionInput from '../CRUD/InsuranceActionInput';

const LifeActionCreate = () => {
  let [newLifeActionLabel, setNewLifeActionLabel] = React.useState();

  const onCreate = e => {
    const db = firebase.firestore();

      label: newLifeActionLabel
    alert('New Life Insurance Added');

  return (
    <Card style={{ padding: '15px' }}>
      <form onSubmit={onCreate}>
          onChange={e => {

        <Button onClick={onCreate}>Create</Button>

Some React Hooks in there

How to select a column name with a space in MySQL

If double quotes does not work , try including the string within square brackets.

For eg:

SELECT "Business Name","Other Name" FROM your_Table

can be changed as

SELECT [Business Name],[Other Name] FROM your_Table

Oracle Partition - Error ORA14400 - inserted partition key does not map to any partition

For this issue need to add the partition for date column values, If last partition 20201231245959, then inserting the 20210110245959 values, this issue will occurs.

For that need to add the 2021 partition into that table


ASP.Net MVC - Read File from HttpPostedFileBase without save

This can be done using httpPostedFileBase class returns the HttpInputStreamObject as per specified here

You should convert the stream into byte array and then you can read file content

Please refer following link]

Hope this helps


The stream that you get from your HTTP call is read-only sequential (non-seekable) and the FileStream is read/write seekable. You will need first to read the entire stream from the HTTP call into a byte array, then create the FileStream from that array.

Taken from here

// Read bytes from http input stream
BinaryReader b = new BinaryReader(file.InputStream);
byte[] binData = b.ReadBytes(file.ContentLength);

string result = System.Text.Encoding.UTF8.GetString(binData);

How to create a list of objects?

I have some hacky answers that are likely to be terrible... but I have very little experience at this point.

a way:

class myClass():
    myInstances = []
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myObj01 = myClass("Foo", "Bar")
myObj02 = myClass("FooBar",  "Baz")

for thisObj in myClass.myInstances:

A hack way to get this done:

import sys
class myClass():
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myObj01 = myClass("Foo", "Bar")
myObj02 = myClass("FooBar",  "Baz")

myInstances = []
myLocals = str(locals()).split("'")
thisStep = 0
for thisLocalsLine in myLocals:
    thisStep += 1
    if "myClass object at" in thisLocalsLine:
        print(myLocals[(thisStep - 2)])
        #myInstances.append(myLocals[(thisStep - 2)])
        myInstances.append(getattr(sys.modules[__name__], myLocals[(thisStep - 2)]))

for thisObj in myInstances:

Another more 'clever' hack:

import sys
class myClass():
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myInstances = []
myClasses = {
    "myObj01": ["Foo", "Bar"],
    "myObj02": ["FooBar",  "Baz"]

for thisClass in myClasses.keys():
    exec("%s = myClass('%s', '%s')" % (thisClass, myClasses[thisClass][0], myClasses[thisClass][1]))
    myInstances.append(getattr(sys.modules[__name__], thisClass))

for thisObj in myInstances:

What is a semaphore?

Consider, a taxi that can accommodate a total of 3(rear)+2(front) persons including the driver. So, a semaphore allows only 5 persons inside a car at a time. And a mutex allows only 1 person on a single seat of the car.

Therefore, Mutex is to allow exclusive access for a resource (like an OS thread) while a Semaphore is to allow access for n number of resources at a time.

Mockito matcher and array of primitives

What works for me was org.mockito.ArgumentMatchers.isA

for example:


that works fine.

the implementation difference of each other is:

public static <T> T any(Class<T> type) {
    reportMatcher(new VarArgAware(type, "<any " + type.getCanonicalName() + ">"));
    return Primitives.defaultValue(type);

public static <T> T isA(Class<T> type) {
    reportMatcher(new InstanceOf(type));
    return Primitives.defaultValue(type);

Show tables, describe tables equivalent in redshift

Tomasz Tybulewicz answer is good way to go.

SELECT * FROM pg_table_def WHERE tablename = 'YOUR_TABLE_NAME' AND schemaname = 'YOUR_SCHEMA_NAME';

If schema name is not defined in search path , that query will show empty result. Please first check search path by below code.


If schema name is not defined in search path , you can reset search path.


How can I generate an MD5 hash?

Take a look at the following link, the Example gets an MD5 Hash of a supplied image: MD5 Hash of an Image

Disallow Twitter Bootstrap modal window from closing

I believe you want to set the backdrop value to static. If you want to avoid the window to close when using the Esc key, you have to set another value.


<a data-controls-modal="your_div_id"

OR if you are using JavaScript:

  backdrop: 'static',
  keyboard: false

How to disable GCC warnings for a few lines of code

I had same issue with external libraries like ROS headers. I like to use following options in CMakeLists.txt for stricter compilation:

set(CMAKE_CXX_FLAGS "-std=c++0x -Wall -Wextra -Wstrict-aliasing -pedantic -Werror -Wunreachable-code ${CMAKE_CXX_FLAGS}")

However doing this causes all kind of pedantic errors in externally included libraries as well. The solution is to disable all pedantic warnings before you include external libraries and re-enable like this:

//save compiler switches
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"

//Bad headers with problem goes here
#include <ros/ros.h>
#include <sensor_msgs/LaserScan.h>

//restore compiler switches
#pragma GCC diagnostic pop

Does it make sense to use Require.js with Angular.js?

This I believe is a subjective question, so I will provide my subjective opinion.

Angular has a modularization mechanism built in. When you create your app, the first thing you would do is

var app = angular.module("myApp");

and then




If you have a look at the angular-seed which is neat starter app for angular, they have separated out the directives, services, controllers etc into different modules and then loaded those modules as dependancies on your main app.

Something like :

var app = angular.module("myApp",["Directives","Controllers","Services"];

Angular also lazy loads these modules ( into memory) not their script files.

In terms of lazy loading script files, to be frank unless you are writing something extremely large it would be an overkill because angular by its very nature reduces the amount of code you write. A typical app written in most other frameworks could expect a reduction in around 30-50% in LOC if written in angular.

Youtube autoplay not working on mobile devices with embedded HTML5 player

The code below was tested on iPhone, iPad (iOS13), Safari (Catalina). It was able to autoplay the YouTube video on all devices. Make sure the video is muted and the playsinline parameter is on. Those are the magic parameters that make it work.

<!DOCTYPE html>
        <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=2.0, minimum-scale=1.0, user-scalable=yes">
<!-- 1. The <iframe> (video player) will replace this <div> tag. -->
<div id="player"></div>

  // 2. This code loads the IFrame Player API code asynchronously.
  var tag = document.createElement('script');

  tag.src = "";
  var firstScriptTag = document.getElementsByTagName('script')[0];
  firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

  // 3. This function creates an <iframe> (and YouTube player)
  //    after the API code downloads.
  var player;
  function onYouTubeIframeAPIReady() {
    player = new YT.Player('player', {
      width: '100%',
      videoId: 'osz5tVY97dQ',
      playerVars: { 'autoplay': 1, 'playsinline': 1 },
      events: {
        'onReady': onPlayerReady

  // 4. The API will call this function when the video player is ready.
  function onPlayerReady(event) {;;

Ruby value of a hash key?

How about this?

puts "ok" if hash_variable["key"] == "X"

You can access hash values with the [] operator

HTML form action and onsubmit issues



get unique machine id

Check out this article. It is very exhaustive and you will find how to extract various hardware information.

Quote from the article:

To get hardware information, you need to create an object of ManagementObjectSearcher class.

using System.Management;
ManagementObjectSearcher searcher = new ManagementObjectSearcher("select * from " + Key);
foreach (ManagementObject share in searcher.Get()) {
    // Some Codes ...

The Key on the code above, is a variable that is replaced with appropriate data. For example, to get the information of the CPU, you have to replace the Key with Win32_Processor.

Using jQuery to see if a div has a child with a certain class

Simple Way

if ($('#text-field > p.filled-text').length != 0)

jquery dialog save cancel button styling

Here is how to add custom classes in jQuery UI Dialog (Version 1.8+):

    'buttons' : {
        'cancel' : {
            priority: 'secondary', class: 'foo bar baz', click: function() {

Is there a way to take a screenshot using Java and save it to some sort of image?

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.swing.*;  

public class HelloWorldFrame extends JFrame implements ActionListener {

JButton b;
public HelloWorldFrame() {
    b = new JButton("Click Here");
    b.setBounds(380, 290, 120, 60);
    setSize(1000, 700);
public void actionPerformed(ActionEvent e)
    if (e.getSource() == b) 
        try {
            Toolkit tk = Toolkit.getDefaultToolkit(); 
            Dimension d = tk.getScreenSize();
            Rectangle rec = new Rectangle(0, 0, d.width, d.height);  
            Robot ro = new Robot();
            BufferedImage img = ro.createScreenCapture(rec);
            File f = new File("myimage.jpg");//set appropriate path
            ImageIO.write(img, "jpg", f);
        } catch (Exception ex) {

public static void main(String[] args) {
    HelloWorldFrame obj = new HelloWorldFrame();

How to check if an element does NOT have a specific class?

You can try this:

<div id="div1" class="myClass">there is a class</div>
<div id="div2"> there is no class2 </div>

    $("#div2").not('.myClass');  // do not have `myClass` class.

Uninitialized Constant MessagesController

Your model is @Messages, change it to @message.

To change it like you should use migration:

def change   rename_table :old_table_name, :new_table_name end 

Of course do not create that file by hand but use rails generator:

rails g migration ChangeMessagesToMessage 

That will generate new file with proper timestamp in name in 'db dir. Then run:

rake db:migrate 

And your app should be fine since then.

How to style a checkbox using CSS

No JavaScript or jQuery required.

Change your checkbox style simple way.

input[type="checkbox"] {_x000D_
  display: none;_x000D_
  border: none !important;_x000D_
  box-shadow: none !important;_x000D_
input[type="checkbox"] + label span {_x000D_
  background: url(;_x000D_
  width: 49px;_x000D_
  height: 49px;_x000D_
  display: inline-block;_x000D_
  vertical-align: middle;_x000D_
input[type="checkbox"]:checked + label span {_x000D_
  background: url(;_x000D_
  width: 49px;_x000D_
  height: 49px;_x000D_
  vertical-align: middle;_x000D_
<input type="checkbox" id="option" />_x000D_
<label for="option"> <span></span> Click me </label>

Here is JsFiddle link

Warning message: In `...` : invalid factor level, NA generated

The warning message is because your "Type" variable was made a factor and "lunch" was not a defined level. Use the stringsAsFactors = FALSE flag when making your data frame to force "Type" to be a character.

> fixed <- data.frame("Type" = character(3), "Amount" = numeric(3))
> str(fixed)
'data.frame':   3 obs. of  2 variables:
 $ Type  : Factor w/ 1 level "": NA 1 1
 $ Amount: chr  "100" "0" "0"
> fixed <- data.frame("Type" = character(3), "Amount" = numeric(3),stringsAsFactors=FALSE)
> fixed[1, ] <- c("lunch", 100)
> str(fixed)
'data.frame':   3 obs. of  2 variables:
 $ Type  : chr  "lunch" "" ""
 $ Amount: chr  "100" "0" "0"

C++: Where to initialize variables in constructor

See Should my constructors use "initialization lists" or "assignment"?

Briefly: in your specific case, it does not change anything. But:

  • for class/struct members with constructors, it may be more efficient to use option 1.
  • only option 1 allows you to initialize reference members.
  • only option 1 allows you to initialize const members
  • only option 1 allows you to initialize base classes using their constructor
  • only option 2 allows you to initialize array or structs that do not have a constructor.

My guess for why option 2 is more common is that option 1 is not well-known, neither are its advantages. Option 2's syntax feels more natural to the new C++ programmer.

How to load images dynamically (or lazily) when users scrolls them into view

I came up with my own basic method which seems to work fine (so far). There's probably a dozen things some of the popular scripts address that I haven't thought of.

Note - This solution is fast and easy to implement but of course not great for performance. Definitely look into the new Intersection Observer as mentioned by Apoorv and explained by if performance is an issue.

The JQuery

$(window).scroll(function() {
    $.each($('img'), function() {
        if ( $(this).attr('data-src') && $(this).offset().top < ($(window).scrollTop() + $(window).height() + 100) ) {
            var source = $(this).data('src');
            $(this).attr('src', source);

Sample html code

    <img src="" data-src="pathtoyour/image1.jpg">
    <img src="" data-src="pathtoyour/image2.jpg">
    <img src="" data-src="pathtoyour/image3.jpg">


When the page is scrolled each image on the page is checked..

$(this).attr('data-src') - if the image has the attribute data-src

and how far those images are from the bottom of the window..

$(this).offset().top < ($(window).scrollTop() + $(window).height() + 100)

adjust the + 100 to whatever you like (- 100 for example)

var source = $(this).data('src'); - gets the value of data-src= aka the image url

$(this).attr('src', source); - puts that value into the src=

$(this).removeAttr('data-src'); - removes the data-src attribute (so your browser doesn't waste resources messing with the images that have already loaded)

Adding To Existing Code

To convert your html, in an editor just search and replace src=" with src="" data-src="

Center a DIV horizontally and vertically

You want to set style

margin: auto;

And remove the positioning styles (top, left, position)

I know this will center horrizontaly but I'm not sure about vertical!

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

Try updating your buildToolVersion to 27.0.2 instead of 27.0.3

The error probably occurring because of compatibility issue with build tools

HTTP Range header

It's a syntactically valid request, but not a satisfiable request. If you look further in that section you see:

If a syntactically valid byte-range-set includes at least one byte- range-spec whose first-byte-pos is less than the current length of the entity-body, or at least one suffix-byte-range-spec with a non- zero suffix-length, then the byte-range-set is satisfiable. Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set is unsatisfiable, the server SHOULD return a response with a status of 416 (Requested range not satisfiable). Otherwise, the server SHOULD return a response with a status of 206 (Partial Content) containing the satisfiable ranges of the entity-body.

So I think in your example, the server should return a 416 since it's not a valid byte range for that file.

How to capitalize the first character of each word in a string


    String text = "jon skeet, miles o'brien, old mcdonald";

    Pattern pattern = Pattern.compile("\\b([a-z])([\\w]*)");
    Matcher matcher = pattern.matcher(text);
    StringBuffer buffer = new StringBuffer();
    while (matcher.find()) {
        matcher.appendReplacement(buffer, +;
    String capitalized = matcher.appendTail(buffer).toString();

Using ng-if as a switch inside ng-repeat?

This one is noteworthy as well

<div ng-repeat="post in posts" ng-if="post.type=='article'">

Replacing H1 text with a logo image: best method for SEO and accessibility?

If accessibility reasons is important then use the first variant (when customer want to see image without styles)

<div id="logo">
    <a href="">
        <img src="logo.png" alt="Stack Overflow" />

No need to conform imaginary SEO requirements, because the HTML code above has correct structure and only you should decide does this suitable for you visitors.

Also you can use the variant with less HTML code

<h1 id="logo">
  <a href=""><span>Stack Overflow</span></a>
/* position code, it may be absolute position or normal - depends on other parts of your site */
#logo {

#logo a {
   width: actual_image_width;
   height: actual_image_height;
   background: url(image.png) no-repeat left top;

/* for accessibility reasons - without styles variant*/
#logo a span {display: none}

Please note that I have removed all other CSS styles and hacks because they didn't correspond to the task. They may be usefull in particular cases only.

PostgreSQL: Which version of PostgreSQL am I running?

Run this query from PostgreSQL:

SELECT version();

How can I sanitize user input with PHP?

Methods for sanitizing user input with PHP:

  • Use Modern Versions of MySQL and PHP.

  • Set charset explicitly:

    • $mysqli->set_charset("utf8");
    • $pdo = new PDO('mysql:host=localhost;dbname=testdb;charset=UTF8', $user, $password);
    • $pdo->exec("set names utf8");
    • $pdo = new PDO(
      "mysql:host=$host;dbname=$db", $user, $pass, 
    • mysql_set_charset('utf8')
      [deprecated in PHP 5.5.0, removed in PHP 7.0.0].
  • Use secure charsets:

    • Select utf8, latin1, ascii.., dont use vulnerable charsets big5, cp932, gb2312, gbk, sjis.
  • Use spatialized function:

    • MySQLi prepared statements:
      $stmt = $mysqli->prepare('SELECT * FROM test WHERE name = ? LIMIT 1'); 
      $param = "' OR 1=1 /*";
      $stmt->bind_param('s', $param);
    • PDO::quote() - places quotes around the input string (if required) and escapes special characters within the input string, using a quoting style appropriate to the underlying driver:

      $pdo = new PDO('mysql:host=localhost;dbname=testdb;charset=UTF8', $user, $password);explicit set the character set
      $pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);disable emulating prepared statements to prevent fallback to emulating statements that MySQL can't prepare natively (to prevent injection)
      $var = $pdo->quote("' OR 1=1 /*");not only escapes the literal, but also quotes it (in single-quote ' characters) $stmt = $pdo->query("SELECT * FROM test WHERE name = $var LIMIT 1");

    • PDO Prepared Statements: vs MySQLi prepared statements supports more database drivers and named parameters:

      $pdo = new PDO('mysql:host=localhost;dbname=testdb;charset=UTF8', $user, $password);explicit set the character set
      $pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);disable emulating prepared statements to prevent fallback to emulating statements that MySQL can't prepare natively (to prevent injection) $stmt = $pdo->prepare('SELECT * FROM test WHERE name = ? LIMIT 1'); $stmt->execute(["' OR 1=1 /*"]);

    • mysql_real_escape_string [deprecated in PHP 5.5.0, removed in PHP 7.0.0].
    • mysqli_real_escape_string Escapes special characters in a string for use in an SQL statement, taking into account the current charset of the connection. But recommended to use Prepared Statements because they are not simply escaped strings, a statement comes up with a complete query execution plan, including which tables and indexes it would use, it is a optimized way.
    • Use single quotes (' ') around your variables inside your query.
  • Check the variable contains what you are expecting for:

    • If you are expecting an integer, use:
      ctype_digit — Check for numeric character(s);
      $value = (int) $value;
      $value = intval($value);
      $var = filter_var('0755', FILTER_VALIDATE_INT, $options);
    • For Strings use:
      is_string() — Find whether the type of a variable is string

      Use Filter Function filter_var() — filters a variable with a specified filter:
      $email = filter_var($email, FILTER_SANITIZE_EMAIL);
      $newstr = filter_var($str, FILTER_SANITIZE_STRING);
      more predefined filters
    • filter_input() — Gets a specific external variable by name and optionally filters it:
      $search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
    • preg_match() — Perform a regular expression match;
    • Write Your own validation function.

Attempted to read or write protected memory

For VS 2013, .NET Framework 4.5.1 also has a AccessViolationException bug (KB2915689) when dealing with SQL Server / TCP Sockets. Upgrading to .NET Framework 4.5.2 corrects this problem.

Reported VS.NET AccessViolationException

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Print line numbers starting at zero using awk

Another option besides awk is nl which allows for options -v for setting starting value and -n <lf,rf,rz> for left, right and right with leading zeros justified. You can also include -s for a field separator such as -s "," for comma separation between line numbers and your data.

In a Unix environment, this can be done as

cat <infile> | ...other stuff... | nl -v 0 -n rz

or simply

nl -v 0 -n rz <infile>


echo "Here 
words" > words.txt

cat words.txt | nl -v 0 -n rz


000000      Here
000001      are
000002      some
000003      words

Finding the average of a list

Or use pandas's Series.mean method:



>>> import pandas as pd
>>> l = [15, 18, 2, 36, 12, 78, 5, 6, 9]
>>> pd.Series(l).mean()

From the docs:

Series.mean(axis=None, skipna=None, level=None, numeric_only=None, **kwargs)

And here is the docs for this:

And the whole documentation:

source command not found in sh shell

I found in a gnu Makefile on Ubuntu, (where /bin/sh -> bash)

I needed to use the . command, as well as specify the target script with a ./ prefix (see example below)

source did not work in this instance, not sure why since it should be calling /bin/bash..

My SHELL environment variable is also set to /bin/bash

    $(shell . ./my_script)

Note this sample does not include the tab character; had to format for stack exchange.

Sleep function in ORACLE

There is a good article on this topic: PL/SQL: Sleep without using DBMS_LOCK that helped me out. I used Option 2 wrapped in a custom package. Proposed solutions are:

Option 1: APEX_UTIL.sleep

If APEX is installed you can use the procedure “PAUSE” from the publicly available package APEX_UTIL.

Example – “Wait 5 seconds”:

    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));

Option 2: java.lang.Thread.sleep

An other option is the use of the method “sleep” from the Java class “Thread”, which you can easily use through providing a simple PL/SQL wrapper procedure:

Note: Please remember, that “Thread.sleep” uses milliseconds!

--- create ---
AS LANGUAGE JAVA NAME 'java.lang.Thread.sleep(long)';

--- use ---
    DBMS_OUTPUT.PUT_LINE('Start ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));
    SLEEP(5 * 1000);
    DBMS_OUTPUT.PUT_LINE('End   ' || to_char(SYSDATE, 'YYYY-MM-DD HH24:MI:SS'));

How to set the min and max height or width of a Frame?

A workaround - at least for the minimum size: You can use grid to manage the frames contained in root and make them follow the grid size by setting sticky='nsew'. Then you can use root.grid_rowconfigure and root.grid_columnconfigure to set values for minsize like so:

from tkinter import Frame, Tk

class MyApp():
    def __init__(self):
        self.root = Tk()

        self.my_frame_red = Frame(self.root, bg='red')
        self.my_frame_red.grid(row=0, column=0, sticky='nsew')

        self.my_frame_blue = Frame(self.root, bg='blue')
        self.my_frame_blue.grid(row=0, column=1, sticky='nsew')

        self.root.grid_rowconfigure(0, minsize=200, weight=1)
        self.root.grid_columnconfigure(0, minsize=200, weight=1)
        self.root.grid_columnconfigure(1, weight=1)


if __name__ == '__main__':
    app = MyApp()

But as Brian wrote (in 2010 :D) you can still resize the window to be smaller than the frame if you don't limit its minsize.

How to call a method in another class of the same package?

From the Notes of Fred Swartz (fredosaurus) :

There are two types of methods.

  • Instance methods are associated with an object and use the instance variables of that object. This is the default.

  • Static methods use no instance variables of any object of the class they are defined in. If you define a method to be static, you will be given a rude message by the compiler if you try to access any instance variables. You can access static variables, but except for constants, this is unusual. Static methods typically take all they data from parameters and compute something from those parameters, with no reference to variables. This is typical of methods which do some kind of generic calculation. A good example of this are the many utility methods in the predefined Math class.

Qualifying a static call

From outside the defining class, an instance method is called by prefixing it with an object, which is then passed as an implicit parameter to the instance method, eg, inputTF.setText("");

A static method is called by prefixing it with a class name, eg, Math.max(i,j);. Curiously, it can also be qualified with an object, which will be ignored, but the class of the object will be used.


Here is a typical static method:

class MyUtils {
    . . .
    //================================================= mean
    public static double mean(int[] p) {
        int sum = 0;  // sum of all the elements
        for (int i=0; i<p.length; i++) {
            sum += p[i];
        return ((double)sum) / p.length;
    }//endmethod mean
    . . .

The only data this method uses or changes is from parameters (or local variables of course).

Why declare a method static

The above mean() method would work just as well if it wasn't declared static, as long as it was called from within the same class. If called from outside the class and it wasn't declared static, it would have to be qualified (uselessly) with an object. Even when used within the class, there are good reasons to define a method as static when it could be.

  • Documentation. Anyone seeing that a method is static will know how to call it (see below). Similarly, any programmer looking at the code will know that a static method can't interact with instance variables, which makes reading and debugging easier.
  • Efficiency. A compiler will usually produce slightly more efficient code because no implicit object parameter has to be passed to the method.

Calling static methods

There are two cases.

Called from within the same class

Just write the static method name. Eg:

// Called from inside the MyUtils class
double avgAtt = mean(attendance);

Called from outside the class

If a method (static or instance) is called from another class, something must be given before the method name to specify the class where the method is defined. For instance methods, this is the object that the method will access. For static methods, the class name should be specified. Eg:

// Called from outside the MyUtils class.
double avgAtt = MyUtils.mean(attendance); 

If an object is specified before it, the object value will be ignored and the the class of the object will be used.

Accessing static variables

Altho a static method can't access instance variables, it can access static variables. A common use of static variables is to define "constants". Examples from the Java library are Math.PI or Color.RED. They are qualified with the class name, so you know they are static. Any method, static or not, can access static variables. Instance variables can be accessed only by instance methods.

Alternate Call

What's a little peculiar, and not recommended, is that an object of a class may be used instead of the class name to access static methods. This is bad because it creates the impression that some instance variables in the object are used, but this isn't the case.

How to wait until WebBrowser is completely loaded in VB.NET?

Sounds like you want to catch the DocumentCompleted event of your webbrowser control.

MSDN has a couple of good articles about the webbrowser control - WebBrowser Class has lots of examples, and How to: Add Web Browser Capabilities to a Windows Forms Application

assign function return value to some variable using javascript

Or just...

var response = (function() {
    var a;
    // calculate a
    return a;

In this case, the response variable receives the return value of the function. The function executes immediately.

You can use this construct if you want to populate a variable with a value that needs to be calculated. Note that all calculation happens inside the anonymous function, so you don't pollute the global namespace.

Inline style to act as :hover in CSS

If you are only debugging, you might use javascript to modify the css:

<a onmouseover="'underline';" 

Pass variables by reference in JavaScript

I've been playing around with syntax to do this sort of thing, but it requires some helpers that are a little unusual. It starts with not using 'var' at all, but a simple 'DECLARE' helper that creates a local variable and defines a scope for it via an anonymous callback. By controlling how variables are declared, we can choose to wrap them into objects so that they can always be passed by reference, essentially. This is similar to one of the Eduardo Cuomo's answer above, but the solution below does not require using strings as variable identifiers. Here's some minimal code to show the concept.

function Wrapper(val){
    this.VAL = val;
Wrapper.prototype.toString = function(){
    return this.VAL.toString();

function DECLARE(val, callback){
    var valWrapped = new Wrapper(val);    

function INC(ref){
    if(ref && ref.hasOwnProperty('VAL')){
        ref++;//or maybe throw here instead?

    return ref;

DECLARE(5, function(five){ //consider this line the same as 'let five = 5'
console.log("five is now " + five);
INC(five); // increment
console.log("five is incremented to " + five);

Check for special characters (/*-+_@&$#%) in a string?

If the list of acceptable characters is pretty small, you can use a regular expression like this:

Regex.IsMatch(items, "[a-z0-9 ]+", RegexOptions.IgnoreCase);

The regular expression used here looks for any character from a-z and 0-9 including a space (what's inside the square brackets []), that there is one or more of these characters (the + sign--you can use a * for 0 or more). The final option tells the regex parser to ignore case.

This will fail on anything that is not a letter, number, or space. To add more characters to the blessed list, add it inside the square brackets.

transparent navigation bar ios

Swift 3 : extension for Transparent Navigation Bar

extension UINavigationBar {
    func transparentNavigationBar() {
    self.setBackgroundImage(UIImage(), for: .default)
    self.shadowImage = UIImage()
    self.isTranslucent = true

$http get parameters does not work

The 2nd parameter in the get call is a config object. You want something like this:

    .get('accept.php', {
        params: {
            source: link,
            category_id: category
     .success(function (data,status) {
          $scope.info_show = data

See the Arguments section of$http for more detail

How to get class object's name as a string in Javascript?

Immediately after the object is instantiatd, you can attach a property, say name, to the object and assign the string value you expect to it:

var myObj = new someClass();"myObj";


Alternatively, the assignment can be made inside the codes of the class, i.e.

var someClass = function(P)
  // rest of the class definition...

var myObj = new someClass("myObj");

Fixing slow initial load for IIS

Options A, B and D seem to be in the same category since they only influence the initial start time, they do warmup of the website like compilation and loading of libraries in memory.

Using C, setting the idle timeout, should be enough so that subsequent requests to the server are served fast (restarting the app pool takes quite some time - in the order of seconds).

As far as I know, the timeout exists to save memory that other websites running in parallel on that machine might need. The price being that one time slow load time.

Besides the fact that the app pool gets shutdown in case of user inactivity, the app pool will also recycle by default every 1740 minutes (29 hours).

From technet:

Internet Information Services (IIS) application pools can be periodically recycled to avoid unstable states that can lead to application crashes, hangs, or memory leaks.

As long as app pool recycling is left on, it should be enough. But if you really want top notch performance for most components, you should also use something like the Application Initialization Module you mentioned.

Which sort algorithm works best on mostly sorted data?

I'm not going to pretend to have all the answers here, because I think getting at the actual answers may require coding up the algorithms and profiling them against representative data samples. But I've been thinking about this question all evening, and here's what's occurred to me so far, and some guesses about what works best where.

Let N be the number of items total, M be the number out-of-order.

Bubble sort will have to make something like 2*M+1 passes through all N items. If M is very small (0, 1, 2?), I think this will be very hard to beat.

If M is small (say less than log N), insertion sort will have great average performance. However, unless there's a trick I'm not seeing, it will have very bad worst case performance. (Right? If the last item in the order comes first, then you have to insert every single item, as far as I can see, which will kill the performance.) I'm guessing there's a more reliable sorting algorithm out there for this case, but I don't know what it is.

If M is bigger (say equal or great than log N), introspective sort is almost certainly best.

Exception to all of that: If you actually know ahead of time which elements are unsorted, then your best bet will be to pull those items out, sort them using introspective sort, and merge the two sorted lists together into one sorted list. If you could quickly figure out which items are out of order, this would be a good general solution as well -- but I haven't been able to figure out a simple way to do this.

Further thoughts (overnight): If M+1 < N/M, then you can scan the list looking for a run of N/M in a row which are sorted, and then expand that run in either direction to find the out-of-order items. That will take at most 2N comparisons. You can then sort the unsorted items, and do a sorted merge on the two lists. Total comparisons should less than something like 4N+M log2(M), which is going to beat any non-specialized sorting routine, I think. (Even further thought: this is trickier than I was thinking, but I still think it's reasonably possible.)

Another interpretation of the question is that there may be many of out-of-order items, but they are very close to where they should be in the list. (Imagine starting with a sorted list and swapping every other item with the one that comes after it.) In that case I think bubble sort performs very well -- I think the number of passes will be proportional to the furthest out of place an item is. Insertion sort will work poorly, because every out of order item will trigger an insertion. I suspect introspective sort or something like that will work well, too.

Eclipse - debugger doesn't stop at breakpoint

Fix could be as simple as clicking run/skip all breakpoints. Worked for me.

How to display Woocommerce product price by ID number on a custom page?

In woocommerce,

Get regular price :

$price = get_post_meta( get_the_ID(), '_regular_price', true);
// $price will return regular price

Get sale price:

$sale = get_post_meta( get_the_ID(), '_sale_price', true);
// $sale will return sale price

How do I type a TAB character in PowerShell?

Test with [char]9, such as:

$Tab = [char]9
Write-Output "$Tab hello"



How to print variables without spaces between values

To build off what Martjin was saying. I'd use string interpolation/formatting.

In Python 2.x which seems to be what you're using due to the lack of parenthesis around the print function you do:

print 'Value is "%d"' % value

In Python 3.x you'd use the format method instead, so you're code would look like this.

message = 'Value is "{}"'

How do you get the magnitude of a vector in Numpy?

The function you're after is numpy.linalg.norm. (I reckon it should be in base numpy as a property of an array -- say x.norm() -- but oh well).

import numpy as np
x = np.array([1,2,3,4,5])

You can also feed in an optional ord for the nth order norm you want. Say you wanted the 1-norm:


And so on.

Removing space from dataframe columns in pandas

  • To remove white spaces:

1) To remove white space everywhere:

df.columns = df.columns.str.replace(' ', '')

2) To remove white space at the beginning of string:

df.columns = df.columns.str.lstrip()

3) To remove white space at the end of string:

df.columns = df.columns.str.rstrip()

4) To remove white space at both ends:

df.columns = df.columns.str.strip()
  • To replace white spaces with other characters (underscore for instance):

5) To replace white space everywhere

df.columns = df.columns.str.replace(' ', '_')

6) To replace white space at the beginning:

df.columns = df.columns.str.replace('^ +', '_')

7) To replace white space at the end:

df.columns = df.columns.str.replace(' +$', '_')

8) To replace white space at both ends:

df.columns = df.columns.str.replace('^ +| +$', '_')

All above applies to a specific column as well, assume you have a column named col, then just do:

df[col] = df[col].str.strip()  # or .replace as above

Create a zip file and download it

I have experienced exactly the same problem. In my case, the source of it was the permissions of the folder in which I wanted to create the zip file that were all set to read only. I changed it to read and write and it worked.

If the file is not created on your local-server when you run the script, you most probably have the same problem as I did.

CSS3 transition on click using pure CSS

As jeremyjjbrow said, :active pseudo won't persist. But there's a hack for doing it on pure css. You can wrap it on a <a> tag, and apply the :active on it, like this:

<a class="test">
    <img class="crossRotate" src="images/cross.png" alt="Cross Menu button" />

And the css:

.test:active .crossRotate {
    transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);

Try it out... It works (at least on Chrome)!

How to use external ".js" files

I hope this helps someone here: I encountered an issue where I needed to use JavaScript to manipulate some dynamically generated elements. After including the code to my external .js file which I had referenced to between the <script> </script> tags at the head section and it was working perfectly, nothing worked again from the script.Tried using developer tool on FF and it returned null value for the variable holding the new element. I decided to move my script tag to the bottom of the html file just before the </body> tag and bingo every part of the script started to respond fine again.

How to create a testflight invitation code?

after you add the user for testing. the user should get an email. open that email by your iOS device, then click "Start testing" it will bring you to testFlight to download the app directly. If you open that email via computer, and then click "Start testing" it will show you another page which have the instruction of how to install the app. and that invitation code is on the last line. those All upper case letters is the code.

Nested Git repositories?

You may be looking for the Git feature called submodules. This feature helps you manage dependent repositories that are nested inside your main repository.

How to hide the border for specified rows of a table?

Use the CSS property border on the <td>s following the <tr>s you do not want to have the border.

In my example I made a class noBorder that I gave to one <tr>. Then I use a simple selector tr.noBorder td to make the border go away for all the <td>s that are inside of <tr>s with the noBorder class by assigning border: 0.

Note that you do not need to provide the unit (i.e. px) if you set something to 0 as it does not matter anyway. Zero is just zero.

table, tr, td {_x000D_
  border: 3px solid red;_x000D_
tr.noBorder td {_x000D_
  border: 0;_x000D_
  <tr class="noBorder">_x000D_

Here's the output as an image:

Output from HTML

SOAP-ERROR: Parsing WSDL: Couldn't load from <URL>

Try this:

$Wsdl = '';
libxml_disable_entity_loader(false); //adding this worked for me
$Client = new SoapClient($Wsdl);

Best way to randomize an array with .NET

If you're on .NET 3.5, you can use the following IEnumerable coolness:

Random rnd=new Random();
string[] MyRandomArray = MyArray.OrderBy(x => rnd.Next()).ToArray();    

Edit: and here's the corresponding VB.NET code:

Dim rnd As New System.Random
Dim MyRandomArray = MyArray.OrderBy(Function() rnd.Next()).ToArray()

Second edit, in response to remarks that System.Random "isn't threadsafe" and "only suitable for toy apps" due to returning a time-based sequence: as used in my example, Random() is perfectly thread-safe, unless you're allowing the routine in which you randomize the array to be re-entered, in which case you'll need something like lock (MyRandomArray) anyway in order not to corrupt your data, which will protect rnd as well.

Also, it should be well-understood that System.Random as a source of entropy isn't very strong. As noted in the MSDN documentation, you should use something derived from System.Security.Cryptography.RandomNumberGenerator if you're doing anything security-related. For example:

using System.Security.Cryptography;


RNGCryptoServiceProvider rnd = new RNGCryptoServiceProvider();
string[] MyRandomArray = MyArray.OrderBy(x => GetNextInt32(rnd)).ToArray();


static int GetNextInt32(RNGCryptoServiceProvider rnd)
        byte[] randomInt = new byte[4];
        return Convert.ToInt32(randomInt[0]);

How do I validate a date in this format (yyyy-mm-dd) using jquery?

I recommend to use the Using jquery validation plugin and jquery ui date picker

jQuery.validator.addMethod("customDateValidator", function(value, element) {
// dd-mm-yyyy
   var re = /^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$/ ; 
   if (! re.test(value) ) return false
   // parseDate throws exception if the value is invalid
   try{jQuery.datepicker.parseDate( 'dd-mm-yy', value);return true ;}
   catch(e){return false;} 
   "Please enter a valid date format dd-mm-yyyy"

    debug: true,
    rules : {
    title : { required : true, minlength: 4 }, 
    date : { required: true, customDateValidator: true }
}) ;

Using Jquery and date picker just create a function with

// dd-mm-yyyy
var re = /^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$/ ; 
 if (! re.test(value) ) return false
// parseDate throws exception if the value is invalid
try{jQuery.datepicker.parseDate( 'dd-mm-yy', value);return true ;}
catch(e){return false;}

You might use only the regular expression for validation

// dd-mm-yyyy
var re = /^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$/ ; 
return re.test(value) 

Of course the date format should be of your region

Selenium and xPath - locating a link by containing text

@FindBy(xpath = "//span[@class='y2' and contains(text(), 'Your Text')] ") 
private WebElementFacade emailLinkToVerifyAccount;

This approach will work for you, hopefully.

Cordova app not displaying correctly on iPhone X (Simulator)

Please note that this article: has different sizes than above and cordova plugin page:

Default@2x~iphone~anyany.png (= 1334x1334 = 667x667@2x)
Default@2x~iphone~comany.png (= 750x1334 = 375x667@2x)
Default@2x~iphone~comcom.png (= 750x750 = 375x375@2x)
Default@3x~iphone~anyany.png (= 2436x2436 = 812x812@3x)
Default@3x~iphone~anycom.png (= 2436x1242 = 812x414@3x)
Default@3x~iphone~comany.png (= 1242x2436 = 414x812@3x)
Default@2x~ipad~anyany.png (= 2732x2732 = 1366x1366@2x)
Default@2x~ipad~comany.png (= 1278x2732 = 639x1366@2x)

I resized images as above and updated ios platform and cordova-plugin-splashscreen to latest and the flash to white screen after a second issue was fixed. However the initial spash image has a white border at bottom now.

How to initialize a struct in accordance with C programming language standards

I found another way to initialize structs.

The struct:

typedef struct test {
    int num;
    char* str;
} test;


test tt = {
    num: 42,
    str: "nice"

As per GCC’s documentation, this syntax is obsolete since GCC 2.5.

Node.js getaddrinfo ENOTFOUND

Another common source of error for

Error: getaddrinfo ENOTFOUND
    at errnoException (dns.js:37:11)
    at Object.onanswer [as oncomplete] (dns.js:124:16)

is writing the protocol (https, https, ...) when setting the host property in options

  // DON'T WRITE THE `http://`
  var options = { 
    host: '',
    path: '/path/to/resource'

static and extern global variables in C and C++

When you #include a header, it's exactly as if you put the code into the source file itself. In both cases the varGlobal variable is defined in the source so it will work no matter how it's declared.

Also as pointed out in the comments, C++ variables at file scope are not static in scope even though they will be assigned to static storage. If the variable were a class member for example, it would need to be accessible to other compilation units in the program by default and non-class members are no different.

Registering for Push Notifications in Xcode 8/Swift 3.0?

Take a look at this commented code:

import Foundation
import UserNotifications
import ObjectMapper

class AppDelegate{

    let center = UNUserNotificationCenter.current()

extension AppDelegate {

    struct Keys {
        static let deviceToken = "deviceToken"

    // MARK: - UIApplicationDelegate Methods
    func application(_: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {

        if let tokenData: String = String(data: deviceToken, encoding: String.Encoding.utf8) {
            debugPrint("Device Push Token \(tokenData)")

        // Prepare the Device Token for Registration (remove spaces and < >)

    func application(_: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {

    // MARK: - Private Methods
     Register remote notification to send notifications
    func registerRemoteNotification() {

        center.requestAuthorization(options: [.alert, .sound, .badge]) { (granted, error) in

            // Enable or disable features based on authorization.
            if granted  == true {

                DispatchQueue.main.async {
            } else {
                debugPrint("User denied the permissions")

     Deregister remote notification
    func deregisterRemoteNotification() {

    func setDeviceToken(_ token: Data) {
        let token = { String(format: "%02.2hhx", arguments: [$0]) }.joined()
        UserDefaults.setObject(token as AnyObject?, forKey: “deviceToken”)

    class func deviceToken() -> String {
        let deviceToken: String? = UserDefaults.objectForKey(“deviceToken”) as? String

        if isObjectInitialized(deviceToken as AnyObject?) {
            return deviceToken!

        return "123"

    func isObjectInitialized(_ value: AnyObject?) -> Bool {
        guard let _ = value else {
                return false
            return true

extension AppDelegate: UNUserNotificationCenterDelegate {

    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping(UNNotificationPresentationOptions) -> Swift.Void) {

        ("\(notification.request.content.userInfo) Identifier: \(notification.request.identifier)")

        completionHandler([.alert, .badge, .sound])

    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping() -> Swift.Void) {

        debugPrint("\(response.notification.request.content.userInfo) Identifier: \(response.notification.request.identifier)")


Let me know if there is any problem!

How do you exit from a void function in C++?

Use a return statement!



if (condition) return;

You don't need to (and can't) specify any values, if your method returns void.

Map.Entry: How to use it?

Map.Entry is a key and its value combined into one class. This allows you to iterate over Map.entrySet() instead of having to iterate over Map.keySet(), then getting the value for each key. A better way to write what you have is:

for (Map.Entry<String, JButton> entry : listbouton.entrySet())
  String key = entry.getKey();
  JButton value = entry.getValue();


If this wasn't clear let me know and I'll amend my answer.

NuGet: 'X' already has a dependency defined for 'Y'

I faced this error on outdated version of Visual Studio 2010. Due to project configuration I was not able to update this version to newer. Therefore, update of NuGet advised above did not fix things for me.

Root reason for the error in this and similar situations is in dependencies of the package you try to install, which are not compatible with .NET version available in your project.

Universal solution is not obligatory update of Visual Studio or .NET but in installation of older NuGet versions of the same package compatible with your system.

It is not possible to tell for sure, which of earlier versions will work. In my case, this command installed the package without any NuGet updates.

Install-Package X -Version [compatible version number]

How to create a date and time picker in Android?

The URLs you link to show how to pop up a dialog with a time picker and another dialog with a date picker. However you need to be aware that you can use those UI widgets directly in your own layout. You could build your own dialog that includes both a TimePicker and DatePicker in the same view, thus accomplishing what I think you are looking for.

In other words, instead of using TimePickerDialog and DatePickerDialog, just use the UI widgets TimePicker and DatePicker directly in your own dialog or activity.

Multithreading in Bash

Bash job control involves multiple processes, not multiple threads.

You can execute a command in background with the & suffix.

You can wait for completion of a background command with the wait command.

You can execute multiple commands in parallel by separating them with |. This provides also a synchronization mechanism, since stdout of a command at left of | is connected to stdin of command at right.

No newline at end of file

Your original file probably had no newline character.

However, some editors like gedit in linux silently adds newline at end of file. You cannot get rid of this message while using this kind of editors.

What I tried to overcome this issue is to open file with visual studio code editor

This editor clearly shows the last line and you can delete the line as you wish.

SQL Server : converting varchar to INT

You could try updating the table to get rid of these characters:

UPDATE dbo.[audit]
  SET UserID = REPLACE(UserID, CHAR(0), '')

But then you'll also need to fix whatever is putting this bad data into the table in the first place. In the meantime perhaps try:

  FROM dbo.[audit];

But that is not a long term solution. Fix the data (and the data type while you're at it). If you can't fix the data type immediately, then you can quickly find the culprit by adding a check constraint:

ALTER TABLE dbo.[audit]
  ADD CONSTRAINT do_not_allow_stupid_data


Ok, so that is definitely a 4-digit integer followed by six instances of CHAR(0). And the workaround I posted definitely works for me:

INSERT @foo SELECT 0x31353831000000000000;

-- this succeeds:

-- this fails:

Please confirm that this code on its own (well, the first SELECT, anyway) works for you. If it does then the error you are getting is from a different non-numeric character in a different row (and if it doesn't then perhaps you have a build where a particular bug hasn't been fixed). To try and narrow it down you can take random values from the following query and then loop through the characters:

  FROM dbo.[audit]
  WHERE UserID LIKE '%[^0-9]%';

So take a random row, and then paste the output into a query like this:

SET @x = CONVERT(VARCHAR(32), 0x...); -- paste the value here
SET @i = 1;
WHILE @i <= LEN(@x)
  PRINT RTRIM(@i) + ' = ' + RTRIM(ASCII(SUBSTRING(@x, @i, 1)))
  SET @i = @i + 1;

This may take some trial and error before you encounter a row that fails for some other reason than CHAR(0) - since you can't really filter out the rows that contain CHAR(0) because they could contain CHAR(0) and CHAR(something else). For all we know you have values in the table like:

SELECT '15' + CHAR(9) + '23' + CHAR(0);

...which also can't be converted to an integer, whether you've replaced CHAR(0) or not.

I know you don't want to hear it, but I am really glad this is painful for people, because now they have more war stories to push back when people make very poor decisions about data types.

In what cases will HTTP_REFERER be empty

HTTP_REFERER - sent by the browser, stating the last page the browser viewed!

If you trusting [HTTP_REFERER] for any reason that is important, you should not, since it can be faked easily:

  1. Some browsers limit access to not allow HTTP_REFERER to be passed
  2. Type a address in the address bar will not pass the HTTP_REFERER
  3. open a new browser window will not pass the HTTP_REFERER, because HTTP_REFERER = NULL
  4. has some browser addon that blocks it for privacy reasons. Some firewalls and AVs do to.

Try this firefox extension, you'll be able to set any headers you want:

@Master of Celebration:


extensions: refspoof, refontrol, modify headers, no-referer

Completely disable: the option is available in about:config under "network.http.sendRefererHeader" and you want to set this to 0 to disable referer passing.

Google chrome / Chromium:

extensions: noref, spoofy, external noreferrer

Completely disable: Chnage ~/.config/google-chrome/Default/Preferences or ~/.config/chromium/Default/Preferences and set this:

   "enable_referrers": false,

Or simply add --no-referrers to shortcut or in cli:

google-chrome --no-referrers


Completely disable: Settings > Preferences > Advanced > Network, and uncheck "Send referrer information"

Spoofing web service:

Standalone filtering proxy (spoof any header):


Spoofing http_referer when using wget


Spoofing http_referer when using curl

-e, --referer

Spoofing http_referer wth telnet

telnet 80 (press return)
GET /index.html HTTP/1.0 (press return)
Referer: (press return)
(press return again)

How to make html table vertically scrollable

Here's my solution (in Spring with Thymeleaf and jQuery):


<!DOCTYPE html>
        <div id="objects" th:fragment="ObjectList">
            <div id='cap'>
            <div id="hdr">
                    <div class="Cell">Name</div>
                        <div class="Cell">Type</div>
            <div id="bdy">
                <div th:each="object : ${objectlist}">
                        <div class="Cell" th:text="${}">name</div>
                        <div class="Cell" th:text="${object.type}">type</div>


#cap span {
    display: table-caption;
    border:2px solid;
    font-size: 200%;
    padding: 3px;
#hdr {
    border:2px solid;
#bdy {
    border:2px solid;
#objects #bdy {
    overflow-y: auto;
#hdr div div{
    text-align: right;
#hdr div:first-child {
    text-align: left;
#bdy div div {
    text-align: right;
#bdy div div:first-child {
    text-align: left;
    display: table-cell;
    border: solid;
    border-width: thin;
    padding-left: 5px;
    padding-right: 5px;


    var divs = ['#objects'];
        if ($(div).length > 0)
            var widths = [];
            var totalWidth = 0;
            $(div+' #hdr div div').each(function() {
            $(div+' #bdy div div').each(function() {
                var col = $(this).index();
                if ( $(this).width() > widths[col] )
                    widths[col] = $(this).width();
            $(div+' #hdr div div').each(function() {
                var newWidth = widths[$(this).index()]+5;
                $(this).css("width", newWidth);
                totalWidth += $(this).outerWidth();
            $(div+' #bdy div div').each(function() {
                $(this).css("width", widths[$(this).index()]+5);
            $(div+' #hdr').css("width", totalWidth);
            $(div+' #bdy').css("width", totalWidth+($(div+' #bdy').css('overflow-y')=='auto'?15:0));

Mixing C# & VB In The Same Project

No, not in the same project.but you can use them in the same solution. though you need to take care that your code is CLS compliant. That means you must not have used such functionality/feature that is not understand by other language. For example VB does not understand unsigned ints.

TypeError: $ is not a function WordPress

There is an easy way to fix it. Just install a plugin and active it. For more : .

Tested with Wordpress version 5.3.

Bootstrap full responsive navbar with logo or brand name text

The placeholder image you're including has a height of 50px. It is wrapped in an anchor (.navbar-brand) with a padding-top of 15px and a height of 50px. That's why the placeholder logo flows out of the bar. Try including a smaller image or play with the anchor's padding by assigning a class or an id to it wich you can reference in your css.

EDIT Or remove the static height: 50px from .navbar-brand. Your navbar will then take the height of its highest child.

h3 in bootstrap by default has a padding-top of 20px. Again, it is wrapped with that padding-top: 15px anchor. That's why it's not vertically centered like you want it. You could give the h3 a class or and id that resets the margin-top. And the same you could do with the padding of the anchor.

Here's something to play with:,output

React PropTypes : Allow different types of PropTypes for one prop

This might work for you:

height: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),

WCF service startup error "This collection already contains an address with scheme http"

And in my case it was simple: I used 'Add WCF Service' wizard in Visual Studio, which automatically created corresponding sections in app.config. Then I went on reading How to: Host a WCF Service in a Managed Application. The problem was: I didn't need to specify the url to run the web service.


using (ServiceHost host = new ServiceHost(typeof(HelloWorldService), baseAddress))


using (ServiceHost host = new ServiceHost(typeof(HelloWorldService))

And the error is gone.

Generic idea: if you provide base address as a param and specify it in config, you get this error. Most probably, that's not the only way to get the error, thou.

Can the :not() pseudo-class have multiple arguments?

Starting from CSS Selectors 4 using multiple arguments in the :not selector becomes possible (see here).

In CSS3, the :not selector only allows 1 selector as an argument. In level 4 selectors, it can take a selector list as an argument.


/* In this example, all p elements will be red, except for 
   the first child and the ones with the class special. */

p:not(:first-child, .special) {
  color: red;

Unfortunately, browser support is limited. For now, it only works in Safari.

Uri not Absolute exception getting while calling Restful Webservice

For others who landed in this error and it's not 100% related to the OP question, please check that you are passing the value and it is not null in case of spring-boot: @Value annotation.

How do I iterate and modify Java Sets?

I don't like very much iterator's semantic, please consider this as an option. It's also safer as you publish less of your internal state

private Map<String, String> JSONtoMAP(String jsonString) {

    JSONObject json = new JSONObject(jsonString);
    Map<String, String> outMap = new HashMap<String, String>();

    for (String curKey : (Set<String>) json.keySet()) {
        outMap.put(curKey, json.getString(curKey));

    return outMap;


How can I parse a String to BigDecimal?

Try this

 String str="10,692,467,440,017.120".replaceAll(",","");
 BigDecimal bd=new BigDecimal(str);

Find out which remote branch a local branch is tracking

Here is a command that gives you all tracking branches (configured for 'pull'), see:

$ git branch -vv
  main   aaf02f0 [main/master: ahead 25] Some other commit
* master add0a03 [jdsumsion/master] Some commit

You have to wade through the SHA and any long-wrapping commit messages, but it's quick to type and I get the tracking branches aligned vertically in the 3rd column.

If you need info on both 'pull' and 'push' configuration per branch, see the other answer on git remote show origin.


Starting in git version 1.8.5 you can show the upstream branch with git status and git status -sb

Which version of Python do I have installed?

For bash scripts this would be the easiest way:

# In the form major.minor.micro e.g. '3.6.8'
# The second part excludes the 'Python ' prefix 
PYTHON_VERSION=`python3 --version | awk '{print $2}'`
echo "python3 version: ${PYTHON_VERSION}"
python3 version: 3.6.8

And if you just need the major.minor version (e.g. 3.6) you can either use the above and then pick the first 3 characters:

PYTHON_VERSION=`python3 --version | awk '{print $2}'`
echo "python3 major.minor: ${PYTHON_VERSION:0:3}"
python3 major.minor: 3.6


PYTHON_VERSION=`python3 -c 'import sys; print(str(sys.version_info[0])+"."+str(sys.version_info[1]))'`
echo "python3 major.minor: ${PYTHON_VERSION}"
python3 major.minor: 3.6

String Comparison in Java

The String.compareTo(..) method performs lexicographical comparison. Lexicographically == alphebetically.

How do I add 1 day to an NSDate?

update for swift 5

let nextDate = fromDate.addingTimeInterval(60*60*24)

Regex using javascript to return just numbers

For number with decimal fraction and minus sign, I use this snippet:

const NUMERIC_REGEXP = /[-]{0,1}[\d]*[.]{0,1}[\d]+/g;

const numbers = '2.2px 3.1px 4px -7.6px obj.key'.match(NUMERIC_REGEXP)

console.log(numbers); // ["2.2", "3.1", "4", "-7.6"]

Update: - 7/9/2018

Found a tool which allows you to edit regular expression visually: JavaScript Regular Expression Parser & Visualizer.


Here's another one with which you can even debugger regexp: Online regex tester and debugger.


Another one: RegExr.


Regexper and Regex Pal.

Batch file include external file for variables

:: savevars.bat
:: Use $ to prefix any important variable to save it for future runs.


REM Load variables
IF EXIST config.txt FOR /F "delims=" %%A IN (config.txt) DO SET "%%A"

REM Change variables
    SET $RunCount=1
) ELSE SET /A $RunCount+=1

REM Display variables

REM Save variables
SET $>config.txt






The technique outlined above can also be used to share variables among multiple batch files.