Programs & Examples On #Perl critic

Perl::Critic is an extensible framework for creating and applying coding standards to Perl source code. Essentially, it is a static source code analysis engine. Perl::Critic is distributed with a number of Perl::Critic::Policy modules that attempt to enforce various coding guidelines.

APR based Apache Tomcat Native library was not found on the java.library.path?

I resolve this (On Eclipse IDE) by delete my old server and create the same again. This error is because you don't proper terminate Tomcat server and close Eclipse.

How to Compare a long value is equal to Long value

Since Java 7 you can use java.util.Objects.equals(Object a, Object b):

These utilities include null-safe or null-tolerant methods

Long id1 = null;
Long id2 = 0l;
Objects.equals(id1, id2));

Can we execute a java program without a main() method?

Now - no

Prior to Java 7:

Yes, sequence is as follows:

  • jvm loads class
  • executes static blocks
  • looks for main method and invokes it

So, if there's code in a static block, it will be executed. But there's no point in doing that.

How to test that:

public final class Test {
    static {

Then if you try to run the class (either form command line with java Test or with an IDE), the result is:

java.lang.NoSuchMethodError: main

Adding a favicon to a static HTML page

You can make a .png image and then use one of the following snippets between the <head> tags of your static HTML documents:

<link rel="icon" type="image/png" href="/favicon.png"/>
<link rel="icon" type="image/png" href=""/>

Recursively add the entire folder to a repository

Scenario / Solution 1:
Ensure your Folder / Sub-folder is not in the .gitignore file, by any chance.

Scenario / Solution 2:
By default, git add . works recursively.

Scenario / Solution 3:
git add --all :/ works smoothly, where git add . doesn't (work).
(@JasonHartley's comment)

Scenario / Solution 4:
The issue I personally faced was adding Subfolders or Files, which were common between multiple Folders.

For example:

So Git was recommending me to add git submodule, which I tried but was a pain.

Finally what worked for me was:

1. git add one file that's at the last end / level of a Folder.
For example:
git add Folder/Subfolder-L1/Subfolder-L2/Subfolder-L3/...file123.txt

2. git add --all :/ now.
It'll very swiftly add all the Folders, Subfolders and files.

undefined offset PHP error

Undefined offset means there's an empty array key for example:

$a = array('Felix','Jon','Java');

// This will result in an "Undefined offset" because the size of the array
// is three (3), thus, 0,1,2 without 3
echo $a[3];

You can solve the problem using a loop (while):

$i = 0;
while ($row = mysqli_fetch_assoc($result)) {
    // Increase count by 1, thus, $i=1

    $groupname[$i] = base64_decode(base64_decode($row['groupname']));

    // Set the first position of the array to null or empty
    $groupname[0] = "";

show loading icon until the page is load?

The easiest way to put the loader in the website.


<div id="loading"></div>


#loading {
position: fixed;
width: 100%;
height: 100vh;
background: #fff url('images/loader.gif') no-repeat center center;
z-index: 9999;


jQuery(document).ready(function() {

What does it mean: The serializable class does not declare a static final serialVersionUID field?

it must be changed whenever anything changes that affects the serialization (additional fields, removed fields, change of field order, ...)

That's not correct, and you will be unable to cite an authoriitative source for that claim. It should be changed whenever you make a change that is incompatible under the rules given in the Versioning of Serializable Objects section of the Object Serialization Specification, which specifically does not include additional fields or change of field order, and when you haven't provided readObject(), writeObject(), and/or readResolve() or /writeReplace() methods and/or a serializableFields declaration that could cope with the change.

'Use of Unresolved Identifier' in Swift

Sometimes the compiler gets confused about the syntax in your class. This happens a lot if you paste in source from somewhere else.

Try reducing the "unresolved" source file down to the bare minimum, cleaning and building. Once it builds successfully add all the complexity back to your class.

This has made it go away for me when re-starting Xcode did not work.

Fastest way to update 120 Million records

If the table has an index which you can iterate over I would put update top(10000) statement in a while loop moving over the data. That would keep the transaction log slim and won't have such a huge impact on the disk system. Also, I would recommend to play with maxdop option (setting it closer to 1).

Unix shell script find out which directory the script file resides?

BASE_DIR="$(cd "$(dirname "$0")"; pwd)";
echo "BASE_DIR => $BASE_DIR"

Autowiring two beans implementing same interface - how to set default bean to autowire?

For Spring 2.5, there's no @Primary. The only way is to use @Qualifier.

SQL split values to multiple rows

I have take the reference from here with changed column name.


CREATE FUNCTION strSplit(x VARCHAR(65000), delim VARCHAR(12), pos INTEGER) 
  DECLARE output VARCHAR(65000);
                 , LENGTH(SUBSTRING_INDEX(x, delim, pos - 1)) + 1)
                 , delim
                 , '');
  IF output = '' THEN SET output = null; END IF;
  RETURN output;
END $$


  SET i = 1;
    INSERT INTO GoodTable (id, name)
      SELECT id, strSplit(name, ',', i) FROM BadTable
      WHERE strSplit(name, ',', i) IS NOT NULL;
    SET i = i + 1;
END $$


Using ConfigurationManager to load config from an arbitrary location

I provided the configuration values to word hosted .nET Compoent as follows.

A .NET Class Library component being called/hosted in MS Word. To provide configuration values to my component, I created winword.exe.config in C:\Program Files\Microsoft Office\OFFICE11 folder. You should be able to read configurations values like You do in Traditional .NET.

string sMsg = System.Configuration.ConfigurationManager.AppSettings["WSURL"];

How to set the color of "placeholder" text?

For giving placeholder a color just use these lines of code:

::-webkit-input-placeholder { color: red; }
::-moz-placeholder {color: red; }
:-ms-input-placeholder { color: red; } 
:-o-input-placeholder { color: red; } 

How to disable Compatibility View in IE

The answer given by FelixFett worked for me. To reiterate:

<meta http-equiv="X-UA-Compatible" content="IE=11; IE=10; IE=9; IE=8; IE=7; IE=EDGE" />

I have it as the first 'meta' tag in my code. I added 10 and 11 as those are versions that are published now for Internet Explorer.

I would've just commented on his answer but I do not have a high enough reputation...

Jquery UI datepicker. Disable array of Dates

   beforeShowDay: function(date){
       var string = jQuery.datepicker.formatDate('yy-mm-dd', date);
       return [ array.indexOf(string) == -1 ]

Javascript Date - set just the date, ignoring time?

var today = new Date();
var year = today.getFullYear();
var mes = today.getMonth()+1;
var dia = today.getDate();
var fecha =dia+"-"+mes+"-"+year;

Converting EditText to int? (Android)

you have to used.

String value= et.getText().toString();
int finalValue=Integer.parseInt(value);

if you have only allow enter number then set EditText property.


if this is helpful then accept otherwise put your comment.

How to convert data.frame column from Factor to numeric

This is FAQ 7.10. Others have shown how to apply this to a single column in a data frame, or to multiple columns in a data frame. But this is really treating the symptom, not curing the cause.

A better approach is to use the colClasses argument to read.table and related functions to tell R that the column should be numeric so that it never creates a factor and creates numeric. This will put in NA for any values that do not convert to numeric.

Another better option is to figure out why R does not recognize the column as numeric (usually a non numeric character somewhere in that column) and fix the original data so that it is read in properly without needing to create NAs.

Best is a combination of the last 2, make sure the data is correct before reading it in and specify colClasses so R does not need to guess (this can speed up reading as well).

What does /p mean in set /p?

The /P switch allows you to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. The promptString can be empty.

Two ways I've used it... first:

SET /P variable=

When batch file reaches this point (when left blank) it will halt and wait for user input. Input then becomes variable.

And second:

SET /P variable=<%temp%\filename.txt

Will set variable to contents (the first line) of the txt file. This method won't work unless the /P is included. Both tested on Windows 8.1 Pro, but it's the same on 7 and 10.

Non-conformable arrays error in code

The problem is that omega in your case is matrix of dimensions 1 * 1. You should convert it to a vector if you wish to multiply t(X) %*% X by a scalar (that is omega)

In particular, you'll have to replace this line:

omega   = rgamma(1,a0,1) / L0


omega   = as.vector(rgamma(1,a0,1) / L0)

everywhere in your code. It happens in two places (once inside the loop and once outside). You can substitute as.vector(.) or c(t(.)). Both are equivalent.

Here's the modified code that should work:

gibbs = function(data, m01 = 0, m02 = 0, k01 = 0.1, k02 = 0.1, 
                     a0 = 0.1, L0 = 0.1, nburn = 0, ndraw = 5000) {
    m0      = c(m01, m02) 
    C0      = matrix(nrow = 2, ncol = 2) 
    C0[1,1] = 1 / k01 
    C0[1,2] = 0 
    C0[2,1] = 0 
    C0[2,2] = 1 / k02 
    beta    = mvrnorm(1,m0,C0) 
    omega   = as.vector(rgamma(1,a0,1) / L0)
    draws   = matrix(ncol = 3,nrow = ndraw) 
    it      = -nburn 

    while (it < ndraw) {
        it    = it + 1 
        C1    = solve(solve(C0) + omega * t(X) %*% X) 
        m1    = C1 %*% (solve(C0) %*% m0 + omega * t(X) %*% y)
        beta  = mvrnorm(1, m1, C1) 
        a1    = a0 + n / 2 
        L1    = L0 + t(y - X %*% beta) %*% (y - X %*% beta) / 2 
        omega = as.vector(rgamma(1, a1, 1) / L1)
        if (it > 0) { 
            draws[it,1] = beta[1]
            draws[it,2] = beta[2]
            draws[it,3] = omega

How to find the highest value of a column in a data frame in R?

In response to finding the max value for each column, you could try using the apply() function:

> apply(ozone, MARGIN = 2, function(x) max(x, na.rm=TRUE))
  Ozone Solar.R    Wind    Temp   Month     Day 
   41.0   313.0    20.1    74.0     5.0     9.0 

Assign variable value inside if-statement

Yes, you can assign the value of variable inside if.

I wouldn't recommend it. The problem is, it looks like a common error where you try to compare values, but use a single = instead of == or ===.

It will be better if you do something like this:

int v;
if((v = someMethod()) != 0) 
   return true;

What is the best way to parse html in C#?

I've written some code that provides "LINQ to HTML" functionality. I thought I would share it here. It is based on Majestic 12. It takes the Majestic-12 results and produces LINQ XML elements. At that point you can use all your LINQ to XML tools against the HTML. As an example:

        IEnumerable<XNode> auctionNodes = Majestic12ToXml.Majestic12ToXml.ConvertNodesToXml(byteArrayOfAuctionHtml);

        foreach (XElement anchorTag in auctionNodes.OfType<XElement>().DescendantsAndSelf("a")) {

            if (anchorTag.Attribute("href") == null)


I wanted to use Majestic-12 because I know it has a lot of built-in knowledge with regards to HTML that is found in the wild. What I've found though is that to map the Majestic-12 results to something that LINQ will accept as XML requires additional work. The code I'm including does a lot of this cleansing, but as you use this you will find pages that are rejected. You'll need to fix up the code to address that. When an exception is thrown, check exception.Data["source"] as it is likely set to the HTML tag that caused the exception. Handling the HTML in a nice manner is at times not trivial...

So now that expectations are realistically low, here's the code :)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Majestic12;
using System.IO;
using System.Xml.Linq;
using System.Diagnostics;
using System.Text.RegularExpressions;

namespace Majestic12ToXml {
public class Majestic12ToXml {

    static public IEnumerable<XNode> ConvertNodesToXml(byte[] htmlAsBytes) {

        HTMLparser parser = OpenParser();

        XElement currentNode = new XElement("document");

        HTMLchunk m12chunk = null;

        int xmlnsAttributeIndex = 0;
        string originalHtml = "";

        while ((m12chunk = parser.ParseNext()) != null) {

            try {

                Debug.Assert(!m12chunk.bHashMode);  // popular default for Majestic-12 setting

                XNode newNode = null;
                XElement newNodesParent = null;

                switch (m12chunk.oType) {
                    case HTMLchunkType.OpenTag:

                        // Tags are added as a child to the current tag, 
                        // except when the new tag implies the closure of 
                        // some number of ancestor tags.

                        newNode = ParseTagNode(m12chunk, originalHtml, ref xmlnsAttributeIndex);

                        if (newNode != null) {
                            currentNode = FindParentOfNewNode(m12chunk, originalHtml, currentNode);

                            newNodesParent = currentNode;


                            currentNode = newNode as XElement;


                    case HTMLchunkType.CloseTag:

                        if (m12chunk.bEndClosure) {

                            newNode = ParseTagNode(m12chunk, originalHtml, ref xmlnsAttributeIndex);

                            if (newNode != null) {
                                currentNode = FindParentOfNewNode(m12chunk, originalHtml, currentNode);

                                newNodesParent = currentNode;
                        else {
                            XElement nodeToClose = currentNode;

                            string m12chunkCleanedTag = CleanupTagName(m12chunk.sTag, originalHtml);

                            while (nodeToClose != null && nodeToClose.Name.LocalName != m12chunkCleanedTag)
                                nodeToClose = nodeToClose.Parent;

                            if (nodeToClose != null)
                                currentNode = nodeToClose.Parent;

                            Debug.Assert(currentNode != null);


                    case HTMLchunkType.Script:

                        newNode = new XElement("script", "REMOVED");
                        newNodesParent = currentNode;

                    case HTMLchunkType.Comment:

                        newNodesParent = currentNode;

                        if (m12chunk.sTag == "!--")
                            newNode = new XComment(m12chunk.oHTML);
                        else if (m12chunk.sTag == "![CDATA[")
                            newNode = new XCData(m12chunk.oHTML);
                            throw new Exception("Unrecognized comment sTag");



                    case HTMLchunkType.Text:


            catch (Exception e) {
                var wrappedE = new Exception("Error using Majestic12.HTMLChunk, reason: " + e.Message, e);

                // the original html is copied for tracing/debugging purposes
                originalHtml = new string(htmlAsBytes.Skip(m12chunk.iChunkOffset)
                    .Select(B => (char)B).ToArray()); 

                wrappedE.Data.Add("source", originalHtml);

                throw wrappedE;

        while (currentNode.Parent != null)
            currentNode = currentNode.Parent;

        return currentNode.Nodes();

    static XElement FindParentOfNewNode(Majestic12.HTMLchunk m12chunk, string originalHtml, XElement nextPotentialParent) {

        string m12chunkCleanedTag = CleanupTagName(m12chunk.sTag, originalHtml);

        XElement discoveredParent = null;

        // Get a list of all ancestors
        List<XElement> ancestors = new List<XElement>();
        XElement ancestor = nextPotentialParent;
        while (ancestor != null) {
            ancestor = ancestor.Parent;

        // Check if the new tag implies a previous tag was closed.
        if ("form" == m12chunkCleanedTag) {

            discoveredParent = ancestors
                .Where(XE => m12chunkCleanedTag == XE.Name)
                .Select(XE => XE.Parent)
        else if ("td" == m12chunkCleanedTag) {

            discoveredParent = ancestors
                .TakeWhile(XE => "tr" != XE.Name)
                .Where(XE => m12chunkCleanedTag == XE.Name)
                .Select(XE => XE.Parent)
        else if ("tr" == m12chunkCleanedTag) {

            discoveredParent = ancestors
                .TakeWhile(XE => !("table" == XE.Name
                                    || "thead" == XE.Name
                                    || "tbody" == XE.Name
                                    || "tfoot" == XE.Name))
                .Where(XE => m12chunkCleanedTag == XE.Name)
                .Select(XE => XE.Parent)
        else if ("thead" == m12chunkCleanedTag
                  || "tbody" == m12chunkCleanedTag
                  || "tfoot" == m12chunkCleanedTag) {

            discoveredParent = ancestors
                .TakeWhile(XE => "table" != XE.Name)
                .Where(XE => m12chunkCleanedTag == XE.Name)
                .Select(XE => XE.Parent)

        return discoveredParent ?? nextPotentialParent;

    static string CleanupTagName(string originalName, string originalHtml) {

        string tagName = originalName;

        tagName = tagName.TrimStart(new char[] { '?' });  // for nodes <?xml >

        if (tagName.Contains(':'))
            tagName = tagName.Substring(tagName.LastIndexOf(':') + 1);

        return tagName;

    static readonly Regex _startsAsNumeric = new Regex(@"^[0-9]", RegexOptions.Compiled);

    static bool TryCleanupAttributeName(string originalName, ref int xmlnsIndex, out string result) {

        result = null;
        string attributeName = originalName;

        if (string.IsNullOrEmpty(originalName))
            return false;

        if (_startsAsNumeric.IsMatch(originalName))
            return false;

        // transform xmlns attributes so they don't actually create any XML namespaces
        if (attributeName.ToLower().Equals("xmlns")) {

            attributeName = "xmlns_" + xmlnsIndex.ToString(); ;
        else {
            if (attributeName.ToLower().StartsWith("xmlns:")) {
                attributeName = "xmlns_" + attributeName.Substring("xmlns:".Length);

            // trim trailing \"
            attributeName = attributeName.TrimEnd(new char[] { '\"' });

            attributeName = attributeName.Replace(":", "_");

        result = attributeName;

        return true;

    static Regex _weirdTag = new Regex(@"^<!\[.*\]>$");       // matches "<![if !supportEmptyParas]>"
    static Regex _aspnetPrecompiled = new Regex(@"^<%.*%>$"); // matches "<%@ ... %>"
    static Regex _shortHtmlComment = new Regex(@"^<!-.*->$"); // matches "<!-Extra_Images->"

    static XElement ParseTagNode(Majestic12.HTMLchunk m12chunk, string originalHtml, ref int xmlnsIndex) {

        if (string.IsNullOrEmpty(m12chunk.sTag)) {

            if (m12chunk.sParams.Length > 0 && m12chunk.sParams[0].ToLower().Equals("doctype"))
                return new XElement("doctype");

            if (_weirdTag.IsMatch(originalHtml))
                return new XElement("REMOVED_weirdBlockParenthesisTag");

            if (_aspnetPrecompiled.IsMatch(originalHtml))
                return new XElement("REMOVED_ASPNET_PrecompiledDirective");

            if (_shortHtmlComment.IsMatch(originalHtml))
                return new XElement("REMOVED_ShortHtmlComment");

            // Nodes like "<br <br>" will end up with a m12chunk.sTag==""...  We discard these nodes.
            return null;

        string tagName = CleanupTagName(m12chunk.sTag, originalHtml);

        XElement result = new XElement(tagName);

        List<XAttribute> attributes = new List<XAttribute>();

        for (int i = 0; i < m12chunk.iParams; i++) {

            if (m12chunk.sParams[i] == "<!--") {

                // an HTML comment was embedded within a tag.  This comment and its contents
                // will be interpreted as attributes by Majestic-12... skip this attributes
                for (; i < m12chunk.iParams; i++) {

                    if (m12chunk.sTag == "--" || m12chunk.sTag == "-->")


            if (m12chunk.sParams[i] == "?" && string.IsNullOrEmpty(m12chunk.sValues[i]))

            string attributeName = m12chunk.sParams[i];

            if (!TryCleanupAttributeName(attributeName, ref xmlnsIndex, out attributeName))

            attributes.Add(new XAttribute(attributeName, m12chunk.sValues[i]));

        // If attributes are duplicated with different values, we complain.
        // If attributes are duplicated with the same value, we remove all but 1.
        var duplicatedAttributes = attributes.GroupBy(A => A.Name).Where(G => G.Count() > 1);

        foreach (var duplicatedAttribute in duplicatedAttributes) {

            if (duplicatedAttribute.GroupBy(DA => DA.Value).Count() > 1)
                throw new Exception("Attribute value was given different values");

            attributes.RemoveAll(A => A.Name == duplicatedAttribute.Key);


        return result;

    static HTMLparser OpenParser() {
        HTMLparser oP = new HTMLparser();

        // The code+comments in this function are from the Majestic-12 sample documentation.

        // ...

        // This is optional, but if you want high performance then you may
        // want to set chunk hash mode to FALSE. This would result in tag params
        // being added to string arrays in HTMLchunk object called sParams and sValues, with number
        // of actual params being in iParams. See code below for details.
        // When TRUE (and its default) tag params will be added to hashtable HTMLchunk (object).oParams

        // if you set this to true then original parsed HTML for given chunk will be kept - 
        // this will reduce performance somewhat, but may be desireable in some cases where
        // reconstruction of HTML may be necessary
        oP.bKeepRawHTML = false;

        // if set to true (it is false by default), then entities will be decoded: this is essential
        // if you want to get strings that contain final representation of the data in HTML, however
        // you should be aware that if you want to use such strings into output HTML string then you will
        // need to do Entity encoding or same string may fail later
        oP.bDecodeEntities = true;

        // we have option to keep most entities as is - only replace stuff like &nbsp; 
        // this is called Mini Entities mode - it is handy when HTML will need
        // to be re-created after it was parsed, though in this case really
        // entities should not be parsed at all
        oP.bDecodeMiniEntities = true;

        if (!oP.bDecodeEntities && oP.bDecodeMiniEntities)

        // if set to true, then in case of Comments and SCRIPT tags the data set to oHTML will be
        // extracted BETWEEN those tags, rather than include complete RAW HTML that includes tags too
        // this only works if auto extraction is enabled
        oP.bAutoExtractBetweenTagsOnly = true;

        // if true then comments will be extracted automatically
        oP.bAutoKeepComments = true;

        // if true then scripts will be extracted automatically: 
        oP.bAutoKeepScripts = true;

        // if this option is true then whitespace before start of tag will be compressed to single
        // space character in string: " ", if false then full whitespace before tag will be returned (slower)
        // you may only want to set it to false if you want exact whitespace between tags, otherwise it is just
        // a waste of CPU cycles
        oP.bCompressWhiteSpaceBeforeTag = true;

        // if true (default) then tags with attributes marked as CLOSED (/ at the end) will be automatically
        // forced to be considered as open tags - this is no good for XML parsing, but I keep it for backwards
        // compatibility for my stuff as it makes it easier to avoid checking for same tag which is both closed
        // or open
        oP.bAutoMarkClosedTagsWithParamsAsOpen = false;

        return oP;

Specify a Root Path of your HTML directory for script links?

I recommend using the HTML <base> element:

    <base href="">
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>

In this example, the stylesheet is located in, the script in The advantage of <base> over / is that it is more flexible. Your whole website can be located in a subdirectory of a domain, and you can easily alter the default directory of your website.

regex.test V.S. string.match to know if a string matches a regular expression

Don't forget to take into consideration the global flag in your regexp :

var reg = /abc/g;
!!'abcdefghi'.match(reg); // => true
!!'abcdefghi'.match(reg); // => true
reg.test('abcdefghi');    // => true
reg.test('abcdefghi');    // => false <=

This is because Regexp keeps track of the lastIndex when a new match is found.

Converting newline formatting from Mac to Windows

  1. Install dos2unix with homebrew
  2. Run find ./ -type f -exec dos2unix {} \; to recursively convert all line-endings within current folder

align an image and some text on the same line without using div width?


Inline elements do not use any width or height you specify. To avoid two div and use like this:

 <div id="container">
<img src="tree.png"  align="left"/>
<h1> A very long text(about 300 words) </h1>
            img {
                display: inline;
                width: 100px;
                height: 100px;
            h1 {
                display: inline;


Change your CSS as follows

.container div {
    display: inline-block;


It is the simple method set width Try the following css:

.container div {
.image {
display: inline-block;
float: left;
.texts { 
height: auto;
width: 30%;
display: inline;

Removing white space around a saved image in matplotlib

The most straightforward method is to use plt.tight_layout transformation which is actually more preferable as it doesn't do unnecessary cropping when using plt.savefig

import matplotlib as plt    
plt.plot([1,2,3], [1,2,3])

However, this may not be preferable for complex plots that modifies the figure. Refer to Johannes S's answer that uses plt.subplots_adjust if that's the case.

Count a list of cells with the same background color

Yes VBA is the way to go.

But, if you don't need to have a cell with formula that auto-counts/updates the number of cells with a particular colour, an alternative is simply to use the 'Find and Replace' function and format the cell to have the appropriate colour fill.

Hitting 'Find All' will give you the total number of cells found at the bottom left of the dialogue box.

enter image description here

This becomes especially useful if your search range is massive. The VBA script will be very slow but the 'Find and Replace' function will still be very quick.

How do I check if string contains substring?

I know that best way is str.indexOf(s) !== -1;

I suggest another way(str.replace(s1, "") !== str):

var str = "Hello World!", s1 = "ello", s2 = "elloo";_x000D_
alert(str.replace(s1, "") !== str);_x000D_
alert(str.replace(s2, "") !== str);

How to validate domain credentials?

I`m using the following code to validate credentials. The method shown below will confirm if the credentials are correct and if not wether the password is expired or needs change.

I`ve been looking for something like this for ages... So i hope this helps someone!

using System;
using System.DirectoryServices;
using System.DirectoryServices.AccountManagement;
using System.Runtime.InteropServices;

namespace User
    public static class UserValidation
        [DllImport("advapi32.dll", SetLastError = true)]
        static extern bool LogonUser(string principal, string authority, string password, LogonTypes logonType, LogonProviders logonProvider, out IntPtr token);
        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool CloseHandle(IntPtr handle);
        enum LogonProviders : uint
            Default = 0, // default for platform (use this!)
            WinNT35,     // sends smoke signals to authority
            WinNT40,     // uses NTLM
            WinNT50      // negotiates Kerb or NTLM
        enum LogonTypes : uint
            Interactive = 2,
            Network = 3,
            Batch = 4,
            Service = 5,
            Unlock = 7,
            NetworkCleartext = 8,
            NewCredentials = 9
        public  const int ERROR_PASSWORD_MUST_CHANGE = 1907;
        public  const int ERROR_LOGON_FAILURE = 1326;
        public  const int ERROR_ACCOUNT_RESTRICTION = 1327;
        public  const int ERROR_ACCOUNT_DISABLED = 1331;
        public  const int ERROR_INVALID_LOGON_HOURS = 1328;
        public  const int ERROR_NO_LOGON_SERVERS = 1311;
        public  const int ERROR_INVALID_WORKSTATION = 1329;
        public  const int ERROR_ACCOUNT_LOCKED_OUT = 1909;      //It gives this error if the account is locked, REGARDLESS OF WHETHER VALID CREDENTIALS WERE PROVIDED!!!
        public  const int ERROR_ACCOUNT_EXPIRED = 1793;
        public  const int ERROR_PASSWORD_EXPIRED = 1330;

        public static int CheckUserLogon(string username, string password, string domain_fqdn)
            int errorCode = 0;
            using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domain_fqdn, "ADMIN_USER", "PASSWORD"))
                if (!pc.ValidateCredentials(username, password))
                    IntPtr token = new IntPtr();
                        if (!LogonUser(username, domain_fqdn, password, LogonTypes.Network, LogonProviders.Default, out token))
                            errorCode = Marshal.GetLastWin32Error();
                    catch (Exception)
            return errorCode;

WHERE clause on SQL Server "Text" data type

You can use LIKE instead of =. Without any wildcards this will have the same effect.

        (CastleType TEXT)


FROM   @Village
WHERE  [CastleType] LIKE 'foo' 

text is deprecated. Changing to varchar(max) will be easier to work with.

Also how large is the data likely to be? If you are going to be doing equality comparisons you will ideally want to index this column. This isn't possible if you declare the column as anything wider than 900 bytes though you can add a computed checksum or hash column that can be used to speed this type of query up.

How to convert an integer to a string in any base?

Strings aren't the only choice for representing numbers: you can use a list of integers to represent the order of each digit. Those can easily be converted to a string.

None of the answers reject base < 2; and most will run very slowly or crash with stack overflows for very large numbers (such as 56789 ** 43210). To avoid such failures, reduce quickly like this:

def n_to_base(n, b):
    if b < 2: raise # invalid base
    if abs(n) < b: return [n]
    ret = [y for d in n_to_base(n, b*b) for y in divmod(d, b)]
    return ret[1:] if ret[0] == 0 else ret # remove leading zeros

def base_to_n(v, b):
    h = len(v) // 2
    if h == 0: return v[0]
    return base_to_n(v[:-h], b) * (b**h) + base_to_n(v[-h:], b)

assert ''.join(['0123456789'[x] for x in n_to_base(56789**43210,10)])==str(56789**43210)

Speedwise, n_to_base is comparable with str for large numbers (about 0.3s on my machine), but if you compare against hex you may be surprised (about 0.3ms on my machine, or 1000x faster). The reason is because the large integer is stored in memory in base 256 (bytes). Each byte can simply be converted to a two-character hex string. This alignment only happens for bases that are powers of two, which is why there are special cases for 2,8, and 16 (and base64, ascii, utf16, utf32).

Consider the last digit of a decimal string. How does it relate to the sequence of bytes that forms its integer? Let's label the bytes s[i] with s[0] being the least significant (little endian). Then the last digit is sum([s[i]*(256**i) % 10 for i in range(n)]). Well, it happens that 256**i ends with a 6 for i > 0 (6*6=36) so that last digit is (s[0]*5 + sum(s)*6)%10. From this, you can see that the last digit depends on the sum of all the bytes. This nonlocal property is what makes converting to decimal harder.

IBOutlet and IBAction

Ran into the diagram while looking at key-value coding, thought it might help someone. It helps with understanding of what IBOutlet is.

By looking at the flow, one could see that IBOutlets are only there to match the property name with a control name in the Nib file.

How nib file is loaded, screenshot of Matt's online book for iOS6

How to loop in excel without VBA or macros?

The way to get the results of your formula would be to start in a new sheet.

In cell A1 put the formula

=IF('testsheet'!C1 <= 99,'testsheet'!A1,"") 

Copy that cell down to row 40 In cell B1 put the formula


In cell B2 put the formula

=B1 & A2

Copy that cell down to row 40.

The value you want is now in that column in row 40.

Not really the answer you want, but that is the fastest way to get things done excel wise without creating a custom formula that takes in a range and makes the calculation (which would be more fun to do).

How do I subscribe to all topics of a MQTT broker

Concrete example is very active (at the time of this posting). This is a nice smoke test for a MQTT subscriber linux device:

mosquitto_sub -h -t "#" -v

The "#" is a wildcard for topics and returns all messages (topics): the server had a lot of traffic, so it returned a 'firehose' of messages.

If your MQTT device publishes a topic of irisys/V4D-19230005/ to the test MQTT broker , then you could filter the messages:

mosquitto_sub -h -t "irisys/V4D-19230005/#" -v


  • -h the hostname (default MQTT port = 1883)
  • -t precedes the topic

Python list iterator behavior and next(iterator)

What is happening is that next(a) returns the next value of a, which is printed to the console because it is not affected.

What you can do is affect a variable with this value:

>>> a = iter(list(range(10)))
>>> for i in a:
...    print(i)
...    b=next(a)

Convert object to JSON string in C#

I have used Newtonsoft JSON.NET (Documentation) It allows you to create a class / object, populate the fields, and serialize as JSON.

public class ReturnData 
    public int totalCount { get; set; }
    public List<ExceptionReport> reports { get; set; }  

public class ExceptionReport
    public int reportId { get; set; }
    public string message { get; set; }  

string json = JsonConvert.SerializeObject(myReturnData);

TypeError: unhashable type: 'dict'

A possible solution might be to use the JSON dumps() method, so you can convert the dictionary to a string ---

import json

a={"a":10, "b":20}
b={"b":20, "a":10}
c = [json.dumps(a), json.dumps(b)]

json.dumps(a) in c

Output -

set(['{"a": 10, "b": 20}'])

Apache POI error loading XSSFWorkbook class

Add commons-collections4-x.x.jar file in your build path and try it again. It will work.

You can download it from

How to add images to on GitHub?

In my case I wanted to show a print screen on Github but also on NPM. Even though using the relative path was working within Github, it wasn't working outside of it. Basically, even if I pushed my project to NPM as well (which simply uses the same, the image was never showing.

I tried a few ways, at the end this is what worked for me:


I now see my image correctly on NPM or anywhere else that I could publish my package.

In a Dockerfile, How to update PATH environment variable?

This is discouraged (if you want to create/distribute a clean Docker image), since the PATH variable is set by /etc/profile script, the value can be overridden.

head /etc/profile:

if [ "`id -u`" -eq 0 ]; then
export PATH

At the end of the Dockerfile, you could add:

RUN echo "export PATH=$PATH" > /etc/environment

So PATH is set for all users.

How can I combine two commits into one commit?

Lazy simple version for forgetfuls like me:

git rebase -i HEAD~3 or however many commits instead of 3.

Turn this

pick YourCommitMessageWhatever
pick YouGetThePoint
pick IdkManItsACommitMessage

into this

pick YourCommitMessageWhatever
s YouGetThePoint
s IdkManItsACommitMessage

and do some action where you hit esc then enter to save the changes. [1]

When the next screen comes up, get rid of those garbage # lines [2] and create a new commit message or something, and do the same escape enter action. [1]

Wowee, you have fewer commits. Or you just broke everything.

[1] - or whatever works with your git configuration. This is just a sequence that's efficient given my setup.

[2] - you'll see some stuff like # this is your n'th commit a few times, with your original commits right below these message. You want to remove these lines, and create a commit message to reflect the intentions of the n commits that you're combining into 1.

Synchronous request in Node.js

I actually got exactly what you (and me) wanted, without the use of await, Promises, or inclusions of any (external) library (except our own).

Here's how to do it:

We're going to make a C++ module to go with node.js, and that C++ module function will make the HTTP request and return the data as a string, and you can use that directly by doing:

var myData = newModule.get(url);

ARE YOU READY to get started?

Step 1: make a new folder somewhere else on your computer, we're only using this folder to build the module.node file (compiled from C++), you can move it later.

In the new folder (I put mine in mynewFolder/src for organize-ness):

npm init


npm install node-gyp -g

now make 2 new files: 1, called something.cpp and for put this code in it (or modify it if you want):

#pragma comment(lib, "urlmon.lib")
#include <sstream>
#include <WTypes.h>  
#include <node.h>
#include <urlmon.h> 
#include <iostream>
using namespace std;
using namespace v8;

Local<Value> S(const char* inp, Isolate* is) {
    return String::NewFromUtf8(

Local<Value> N(double inp, Isolate* is) {
    return Number::New(

const char* stdStr(Local<Value> str, Isolate* is) {
    String::Utf8Value val(is, str);
    return *val;

double num(Local<Value> inp) {
    return inp.As<Number>()->Value();

Local<Value> str(Local<Value> inp) {
    return inp.As<String>();

Local<Value> get(const char* url, Isolate* is) {
    IStream* stream;
    HRESULT res = URLOpenBlockingStream(0, url, &stream, 0, 0);

    char buffer[100];
    unsigned long bytesReadSoFar;
    stringstream ss;
    stream->Read(buffer, 100, &bytesReadSoFar);
    while(bytesReadSoFar > 0U) {
        ss.write(buffer, (long long) bytesReadSoFar);
        stream->Read(buffer, 100, &bytesReadSoFar);
    const string tmp = ss.str();
    const char* cstr = tmp.c_str();
    return S(cstr, is);

void Hello(const FunctionCallbackInfo<Value>& arguments) {
    cout << "Yo there!!" << endl;

    Isolate* is = arguments.GetIsolate();
    Local<Context> ctx = is->GetCurrentContext();

    const char* url = stdStr(arguments[0], is);
    Local<Value> pg = get(url,is);

    Local<Object> obj = Object::New(is);


void Init(Local<Object> exports) {
    NODE_SET_METHOD(exports, "get", Hello);

NODE_MODULE(cobypp, Init);

Now make a new file in the same directory called something.gyp and put (something like) this in it:

   "targets": [
           "target_name": "cobypp",
           "sources": [ "src/cobypp.cpp" ]

Now in the package.json file, add: "gypfile": true,

Now: in the console, node-gyp rebuild

If it goes through the whole command and says "ok" at the end with no errors, you're (almost) good to go, if not, then leave a comment..

But if it works then go to build/Release/cobypp.node (or whatever its called for you), copy it into your main node.js folder, then in node.js:

var myCPP = require("./cobypp")
var myData = myCPP.get("").result;


response.end(myData);//or whatever

Understanding .get() method in Python

If d is a dictionary, then d.get(k, v) means, give me the value of k in d, unless k isn't there, in which case give me v. It's being used here to get the current count of the character, which should start at 0 if the character hasn't been encountered before.

What tool to use to draw file tree diagram

Why could you not just make a file structure on the Windows file system and populate it with your desired names, then use a screen grabber like HyperSnap (or the ubiquitous Alt-PrtScr) to capture a section of the Explorer window.

I did this when 'demoing' an internet application which would have collapsible sections, I just had to create files that looked like my desired entries.

HyperSnap gives JPGs at least (probably others but I've never bothered to investigate).

Or you could screen capture the icons +/- from Explorer and use them within MS Word Draw itself to do your picture, but I've never been able to get MS Word Draw to behave itself properly.

What Ruby IDE do you prefer?

I started out with RadRails then moved to Aptana when they took it over, wasn't too bad. Got a macbook and have been using Textmate, never going back.

Jquery get form field value

You can try these lines:

$("#DynamicValueAssignedHere .formdiv form").contents().find("input[name='FirstName']").prevObject[1].value

send/post xml file using curl command line

If that question is connected to your other Hudson questions use the command they provide. This way with XML from the command line:

$ curl -X POST -d '<run>...</run>' \

You need to change it a little bit to read from a file:

 $ curl -X POST -d @myfilename http://user:pass@myhost:myport/path/of/url

Read the manpage. following an abstract for -d Parameter.


(HTTP) Sends the specified data in a POST request to the HTTP server, in the same way that a browser does when a user has filled in an HTML form and presses the submit button. This will cause curl to pass the data to the server using the content-type application/x-www-form-urlencoded. Compare to -F/--form.

-d/--data is the same as --data-ascii. To post data purely binary, you should instead use the --data-binary option. To URL-encode the value of a form field you may use --data-urlencode.

If any of these options is used more than once on the same command line, the data pieces specified will be merged together with a separating &-symbol. Thus, using '-d name=daniel -d skill=lousy' would generate a post chunk that looks like 'name=daniel&skill=lousy'.

If you start the data with the letter @, the rest should be a file name to read the data from, or - if you want curl to read the data from stdin. The contents of the file must already be URL-encoded. Multiple files can also be specified. Posting data from a file named 'foobar' would thus be done with --data @foobar.

How to generate a QR Code for an Android application?

zxing does not (only) provide a web API; really, that is Google providing the API, from source code that was later open-sourced in the project.

As Rob says here you can use the Java source code for the QR code encoder to create a raw barcode and then render it as a Bitmap.

I can offer an easier way still. You can call Barcode Scanner by Intent to encode a barcode. You need just a few lines of code, and two classes from the project, under android-integration. The main one is IntentIntegrator. Just call shareText().

how to run two commands in sudo?

If you know the root password, you can try

su -c "<command1> ; <command2>"  

Java: convert List<String> to a String

With Java 8 you can do this without any third party library.

If you want to join a Collection of Strings you can use the new String.join() method:

List<String> list = Arrays.asList("foo", "bar", "baz");
String joined = String.join(" and ", list); // "foo and bar and baz"

If you have a Collection with another type than String you can use the Stream API with the joining Collector:

List<Person> list = Arrays.asList(
  new Person("John", "Smith"),
  new Person("Anna", "Martinez"),
  new Person("Paul", "Watson ")

String joinedFirstNames =
  .collect(Collectors.joining(", ")); // "John, Anna, Paul"

The StringJoiner class may also be useful.

Pycharm/Python OpenCV and CV2 install error

In jetso nano this work for me.

$ git clone
$ cd buildOpenCV

Fastest way to get the first n elements of a List into an Array


list - List<String>

Using Java 8 Streams,

  • to get first N elements from a list into a list,

    List<String> firstNElementsList =;

  • to get first N elements from a list into an Array,

    String[] firstNElementsArray = String[n]);

jQuery get values of checked checkboxes into array

I refactored your code a bit and believe I came with the solution for which you were looking. Basically instead of setting searchIDs to be the result of the .map() I just pushed the values into an array.


  var searchIDs = [];

  $("#find-table input:checkbox:checked").map(function(){


I created a fiddle with the code running.

PHP foreach loop through multidimensional array

If you mean the first and last entry of the array when talking about a.first and a.last, it goes like this:

foreach ($arr_nav as $inner_array) {
    echo reset($inner_array); //apple, orange, pear
    echo end($inner_array); //My Apple, View All Oranges, A Pear

arrays in PHP have an internal pointer which you can manipulate with reset, next, end. Retrieving keys/values works with key and current, but using each might be better in many cases..

Getting time difference between two times in PHP

You can also use DateTime class:

$time1 = new DateTime('09:00:59');
$time2 = new DateTime('09:01:00');
$interval = $time1->diff($time2);
echo $interval->format('%s second(s)');


1 second(s)

Get ID of element that called a function

You can use 'this' in event handler:

document.getElementById("preview").onmouseover = function() {

Or pass event object to handler as follows:

document.getElementById("preview").onmouseover = function(evt) {

It's recommended to use attachEvent(for IE < 9)/addEventListener(IE9 and other browsers) to attach events. Example above is for brevity.

function myHandler(evt) {

var el = document.getElementById("preview");
if (el.addEventListener){
    el.addEventListener('click', myHandler, false); 
} else if (el.attachEvent){
    el.attachEvent('onclick', myHandler);

How to get Time from DateTime format in SQL?

select convert(char(5), tbl_CustomerBooking.CheckInTime, 108) AS [time]
from tbl_CustomerBooking

Removing header column from pandas dataframe

I had the same problem but solved it in this way:

df = pd.read_csv('your-array.csv', skiprows=[0])

How can I strip HTML tags from a string in ASP.NET?

Go download HTMLAgilityPack, now! ;) Download LInk

This allows you to load and parse HTML. Then you can navigate the DOM and extract the inner values of all attributes. Seriously, it will take you about 10 lines of code at the maximum. It is one of the greatest free .net libraries out there.

Here is a sample:

            string htmlContents = new System.IO.StreamReader(resultsStream,Encoding.UTF8,true).ReadToEnd();

            HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
            if (doc == null) return null;

            string output = "";
            foreach (var node in doc.DocumentNode.ChildNodes)
                output += node.InnerText;

Programmatically select a row in JTable

You can do it calling setRowSelectionInterval :

table.setRowSelectionInterval(0, 0);

to select the first row.

How can I write a byte array to a file in Java?

You can use IOUtils.write(byte[] data, OutputStream output) from Apache Commons IO.

KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecretKey key = kgen.generateKey();
byte[] encoded = key.getEncoded();
FileOutputStream output = new FileOutputStream(new File("target-file"));
IOUtils.write(encoded, output);

Credit card expiration dates - Inclusive or exclusive?

How do time zones factor in this analysis. Does a card expire in New York before California? Does it depend on the billing or shipping addresses?

How do I combine two data-frames based on two columns?

See the documentation on ?merge, which states:

By default the data frames are merged on the columns with names they both have, 
 but separate specifications of the columns can be given by by.x and by.y.

This clearly implies that merge will merge data frames based on more than one column. From the final example given in the documentation:

x <- data.frame(k1=c(NA,NA,3,4,5), k2=c(1,NA,NA,4,5), data=1:5)
y <- data.frame(k1=c(NA,2,NA,4,5), k2=c(NA,NA,3,4,5), data=1:5)
merge(x, y, by=c("k1","k2")) # NA's match

This example was meant to demonstrate the use of incomparables, but it illustrates merging using multiple columns as well. You can also specify separate columns in each of x and y using by.x and by.y.

Android RatingBar change star colors

RatingBar mRating=(RatingBar)findViewById(;
 LayerDrawable layerDrawable=(LayerDrawable)mRating.getProgressDrawable();
 ("#32CD32"),    PorterDuff.Mode.SRC_ATOP);

for me its working....

How do I use the conditional operator (? :) in Ruby?

The code condition ? statement_A : statement_B is equivalent to

if condition == true

Get the current date and time

Get Current DateTime


How do you split a list into evenly sized chunks?

Lazy loading version

import pprint
pprint.pprint(list(chunks(range(10, 75), 10)))
[range(10, 20),
 range(20, 30),
 range(30, 40),
 range(40, 50),
 range(50, 60),
 range(60, 70),
 range(70, 75)]

Confer this implementation's result with the example usage result of the accepted answer.

Many of the above functions assume that the length of the whole iterable are known up front, or at least are cheap to calculate.

For some streamed objects that would mean loading the full data into memory first (e.g. to download the whole file) to get the length information.

If you however don't know the the full size yet, you can use this code instead:

def chunks(iterable, size):
    Yield successive chunks from iterable, being `size` long.
    :param iterable: The object you want to split into pieces.
    :param size: The size each of the resulting pieces should have.
    i = 0
    while True:
        sliced = iterable[i:i + size]
        if len(sliced) == 0:
            # to suppress stuff like `range(max, max)`.
        # end if
        yield sliced
        if len(sliced) < size:
            # our slice is not the full length, so we must have passed the end of the iterator
        # end if
        i += size  # so we start the next chunk at the right place.
    # end while
# end def

This works because the slice command will return less/no elements if you passed the end of an iterable:

"abc"[0:2] == 'ab'
"abc"[2:4] == 'c'
"abc"[4:6] == ''

We now use that result of the slice, and calculate the length of that generated chunk. If it is less than what we expect, we know we can end the iteration.

That way the iterator will not be executed unless access.

What's the difference between "Solutions Architect" and "Applications Architect"?

There are valid differences between types of architects:

Enterprise architects look at solutions for the enterprise aligining tightly with the enterprise strategy. Eg in a bank, they'll look at the complete IT landscape.

Solution architects focus on a particular solution, for example a new credit card acquiring system in a bank.

Domain architects focus on specific areas, for example an application architect or network architect.

Technical architects generally play the role of solution architects with less focus on the business aspect and more on the techology aspect.

How to insert blank lines in PDF?

You can use "\n" in Paragraph

document.add(new Paragraph("\n\n"));

how to bypass Access-Control-Allow-Origin?

It's a really bad idea to use *, which leaves you wide open to cross site scripting. You basically want your own domain all of the time, scoped to your current SSL settings, and optionally additional domains. You also want them all to be sent as one header. The following will always authorize your own domain in the same SSL scope as the current page, and can optionally also include any number of additional domains. It will send them all as one header, and overwrite the previous one(s) if something else already sent them to avoid any chance of the browser grumbling about multiple access control headers being sent.

class CorsAccessControl
    private $allowed = array();

     * Always adds your own domain with the current ssl settings.
    public function __construct()
        // Add your own domain, with respect to the current SSL settings.
        $this->allowed[] = 'http'
            . ( ( array_key_exists( 'HTTPS', $_SERVER )
                && $_SERVER['HTTPS'] 
                && strtolower( $_SERVER['HTTPS'] ) !== 'off' ) 
                    ? 's' 
                    : null )
            . '://' . $_SERVER['HTTP_HOST'];

     * Optionally add additional domains. Each is only added one time.
    public function add($domain)
        if ( !in_array( $domain, $this->allowed )
            $this->allowed[] = $domain;
     * Send 'em all as one header so no browsers grumble about it.
    public function send()
        $domains = implode( ', ', $this->allowed );
        header( 'Access-Control-Allow-Origin: ' . $domains, true ); // We want to send them all as one shot, so replace should be true here.


$cors = new CorsAccessControl();

// If you are only authorizing your own domain:

// If you are authorizing multiple domains:
foreach ($domains as $domain)

You get the idea.

Mocking python function based on input arguments

Although side_effect can achieve the goal, it is not so convenient to setup side_effect function for each test case.

I write a lightweight Mock (which is called NextMock) to enhance the built-in mock to address this problem, here is a simple example:

from nextmock import Mock

m = Mock()

m.with_args(1, 2, 3).returns(123)

assert m(1, 2, 3) == 123
assert m(3, 2, 1) != 123

It also supports argument matcher:

from nextmock import Arg, Mock

m = Mock()

m.with_args(1, 2, Arg.Any).returns(123)

assert m(1, 2, 1) == 123
assert m(1, 2, "123") == 123

Hope this package could make testing more pleasant. Feel free to give any feedback.

How do I send a POST request with PHP?

There's another CURL method if you are going that way.

This is pretty straightforward once you get your head around the way the PHP curl extension works, combining various flags with setopt() calls. In this example I've got a variable $xml which holds the XML I have prepared to send - I'm going to post the contents of that to example's test method.

$url = '';
$ch = curl_init($url);

curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);
//process $response

First we initialised the connection, then we set some options using setopt(). These tell PHP that we are making a post request, and that we are sending some data with it, supplying the data. The CURLOPT_RETURNTRANSFER flag tells curl to give us the output as the return value of curl_exec rather than outputting it. Then we make the call and close the connection - the result is in $response.

Installing packages in Sublime Text 2

Try using Sublime Package Control to install your packages.

Also take a look at these tips

MySQL - How to parse a string value to DATETIME format inside an INSERT statement?

Use MySQL's STR_TO_DATE() function to parse the string that you're attempting to insert:

INSERT INTO tblInquiry (fldInquiryReceivedDateTime) VALUES
  (STR_TO_DATE('5/15/2012 8:06:26 AM', '%c/%e/%Y %r'))

Sprintf equivalent in Java

Both solutions workto simulate printf, but in a different way. For instance, to convert a value to a hex string, you have the 2 following solutions:

  • with format(), closest to sprintf():

    final static String HexChars = "0123456789abcdef";
    public static String getHexQuad(long v) {
        String ret;
        if(v > 0xffff) ret = getHexQuad(v >> 16); else ret = "";
        ret += String.format("%c%c%c%c",
            HexChars.charAt((int) ((v >> 12) & 0x0f)),
            HexChars.charAt((int) ((v >>  8) & 0x0f)),
            HexChars.charAt((int) ((v >>  4) & 0x0f)),
            HexChars.charAt((int) ( v        & 0x0f)));
        return ret;
  • with replace(char oldchar , char newchar), somewhat faster but pretty limited:

        ret += "ABCD".
            replace('A', HexChars.charAt((int) ((v >> 12) & 0x0f))).
            replace('B', HexChars.charAt((int) ((v >>  8) & 0x0f))).
            replace('C', HexChars.charAt((int) ((v >>  4) & 0x0f))).
            replace('D', HexChars.charAt((int) ( v        & 0x0f)));
  • There is a third solution consisting of just adding the char to ret one by one (char are numbers that add to each other!) such as in:

    ret += HexChars.charAt((int) ((v >> 12) & 0x0f)));
    ret += HexChars.charAt((int) ((v >>  8) & 0x0f)));

...but that'd be really ugly.

Invalid column count in CSV input on line 1 Error

When facing errors with input files of any type, encoding issues are common.

A simple solution might be to open a new file, copy pasting your CSV text in it, then saving it as a new file.

Where is android_sdk_root? and how do I set it.?

on Mac edit .bash_profile use code or vim

code ~/.bash_profile

export ANDROID_SDK_ROOT=~/Library/Android/sdk

export ANDROID_HOME=~/Library/Android/sdk

Can't change z-index with JQuery

That's invalid Javascript syntax; a property name cannot have a -.

Use either zIndex or "z-index".

Can't use modulus on doubles?

fmod(x, y) is the function you use.

How does origin/HEAD get set?

Run the following commands from git CLI:

# move to the wanted commit
git reset --hard <commit-hash> 

# update remote
git push --force origin <branch-name> 

How can I access global variable inside class in Python

I understand using a global variable is sometimes the most convenient thing to do, especially in cases where usage of class makes the easiest thing so much harder (e.g., multiprocessing). I ran into the same problem with declaring global variables and figured it out with some experiments.

The reason that g_c was not changed by the run function within your class is that the referencing to the global name within g_c was not established precisely within the function. The way Python handles global declaration is in fact quite tricky. The command global g_c has two effects:

  1. Preconditions the entrance of the key "g_c" into the dictionary accessible by the built-in function, globals(). However, the key will not appear in the dictionary until after a value is assigned to it.

  2. (Potentially) alters the way Python looks for the variable g_c within the current method.

The full understanding of (2) is particularly complex. First of all, it only potentially alters, because if no assignment to the name g_c occurs within the method, then Python defaults to searching for it among the globals(). This is actually a fairly common thing, as is the case of referencing within a method modules that are imported all the way at the beginning of the code.

However, if an assignment command occurs anywhere within the method, Python defaults to finding the name g_c within local variables. This is true even when a referencing occurs before an actual assignment, which will lead to the classic error:

UnboundLocalError: local variable 'g_c' referenced before assignment

Now, if the declaration global g_c occurs anywhere within the method, even after any referencing or assignment, then Python defaults to finding the name g_c within global variables. However, if you are feeling experimentative and place the declaration after a reference, you will be rewarded with a warning:

SyntaxWarning: name 'g_c' is used prior to global declaration

If you think about it, the way the global declaration works in Python is clearly woven into and consistent with how Python normally works. It's just when you actually want a global variable to work, the norm becomes annoying.

Here is a code that summarizes what I just said (with a few more observations):

g_c = 0
print ("Initial value of g_c: " + str(g_c))
print("Variable defined outside of method automatically global? "
      + str("g_c" in globals()))

class TestClass():
    def direct_print(self):
        print("Directly printing g_c without declaration or modification: "
              + str(g_c))
        #Without any local reference to the name
        #Python defaults to search for the variable in globals()
        #This of course happens for all the module names you import

    def mod_without_dec(self):
        g_c = 1
        #A local assignment without declaring reference to global variable
        #makes Python default to access local name
        print ("After mod_without_dec, local g_c=" + str(g_c))
        print ("After mod_without_dec, global g_c=" + str(globals()["g_c"]))

    def mod_with_late_dec(self):
        g_c = 2
        #Even with a late declaration, the global variable is accessed
        #However, a syntax warning will be issued
        global g_c
        print ("After mod_with_late_dec, local g_c=" + str(g_c))
        print ("After mod_with_late_dec, global g_c=" + str(globals()["g_c"]))

    def mod_without_dec_error(self):
            print("This is g_c" + str(g_c))
            print("Error occured while accessing g_c")
            #If you try to access g_c without declaring it global
            #but within the method you also alter it at some point
            #then Python will not search for the name in globals()
            #!!!!!Even if the assignment command occurs later!!!!!
        g_c = 3

    def sound_practice(self):
        global g_c
        #With correct declaration within the method
        #The local name g_c becomes an alias for globals()["g_c"]
        g_c = 4
        print("In sound_practice, the name g_c points to: " + str(g_c))

t = TestClass()

SQL Error: ORA-00942 table or view does not exist

Because this post is the top one found on stackoverflow when searching for "ORA-00942: table or view does not exist insert", I want to mention another possible cause of this error (at least in Oracle 12c): a table uses a sequence to set a default value and the user executing the insert query does not have select privilege on the sequence. This was my problem and it took me an unnecessarily long time to figure it out.

To reproduce the problem, execute the following SQL as user1:

create sequence seq_customer_id;

create table customer (
c_id number(10) default seq_customer_id.nextval primary key,
name varchar(100) not null,
surname varchar(100) not null

grant select, insert, update, delete on customer to user2;

Then, execute this insert statement as user2:

insert into user1.customer (name,surname) values ('michael','jackson');

The result will be "ORA-00942: table or view does not exist" even though user2 does have insert and select privileges on user1.customer table and is correctly prefixing the table with the schema owner name. To avoid the problem, you must grant select privilege on the sequence:

grant select on seq_customer_id to user2;

Find character position and update file name

If you use Excel, then the command would be Find and MID. Here is what it would look like in Powershell.

 $text = "asdfNAME=PC123456<>Diweursejsfdjiwr"

asdfNAME=PC123456<>Diweursejsfdjiwr - Randon line of text, we want PC123456


7 - this is the "FIND" command for Powershell


C1234 - this is the "MID" command for Powershell


PC123456 - tada it has found and cut our text


Saving ssh key fails

For windows use enter button 3 times

Enter file in which to save the key (/c/Users/Rupesh/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again:

its work for me...

How can I create a dynamic button click event on a dynamic button?

The easier one for newbies:

Button button = new Button();
button.Click += new EventHandler(button_Click);

protected void button_Click (object sender, EventArgs e)
    Button button = sender as Button;
    // identify which button was clicked and perform necessary actions

Rails - passing parameters in link_to

link_to "+ Service", controller_action_path(:account_id =>

If it is still not working check the path:

$ rake routes

jQuery Remove string from string

pretty sure you just want the plain old replace function. use like this:


i suppose if you want to remove the trailing comma do this instead:



here is your site specific code:


How to do join on multiple criteria, returning all combinations of both criteria

It sounds like you want to list all the metrics?

SELECT Criteria1, Criteria2, Metric1 As Metric
FROM Table1
SELECT Criteria1, Criteria2, Metric2 As Metric
FROM Table2

If you only want one Criteria1+Criteria2 combination, group them:

SELECT Criteria1, Criteia2, SUM(Metric) AS Metric
    SELECT Criteria1, Criteria2, Metric1 As Metric
    FROM Table1
    SELECT Criteria1, Criteria2, Metric2 As Metric
    FROM Table2
ORDER BY Criteria1, Criteria2

Why SQL Server throws Arithmetic overflow error converting int to data type numeric?

Numeric defines the TOTAL number of digits, and then the number after the decimal.

A numeric(3,2) can only hold up to 9.99.

Convert varchar to uniqueidentifier in SQL Server

If your string contains special characters you can hash it to md5 and then convert it to a guid/uniqueidentifier.

SELECT CONVERT(UNIQUEIDENTIFIER, HASHBYTES('MD5','~öü߀a89b1acd95016ae6b9c8aabb07da2010'))

Dynamically access object property using variable

Finding Object by reference without, strings, Note make sure the object you pass in is cloned , i use cloneDeep from lodash for that

if object looks like

const obj = {data: ['an Object',{person: {name: {first:'nick', last:'gray'} }]

path looks like

const objectPath = ['data',1,'person',name','last']

then call below method and it will return the sub object by path given

const child = findObjectByPath(obj, objectPath)
alert( child) // alerts "last"

const findObjectByPath = (objectIn: any, path: any[]) => {
    let obj = objectIn
    for (let i = 0; i <= path.length - 1; i++) {
        const item = path[i]
        // keep going up to the next parent
        obj = obj[item] // this is by reference
    return obj

How do you tell if a string contains another string in POSIX sh?

Here's yet another solution. This uses POSIX substring parameter expansion, so it works in Bash, Dash, KornShell (ksh), Z shell (zsh), etc.

test "${string#*$word}" != "$string" && echo "$word found in $string"

A functionalized version with some examples:

# contains(string, substring)
# Returns 0 if the specified string contains the specified substring,
# otherwise returns 1.
contains() {
    if test "${string#*$substring}" != "$string"
        return 0    # $substring is in $string
        return 1    # $substring is not in $string

contains "abcd" "e" || echo "abcd does not contain e"
contains "abcd" "ab" && echo "abcd contains ab"
contains "abcd" "bc" && echo "abcd contains bc"
contains "abcd" "cd" && echo "abcd contains cd"
contains "abcd" "abcd" && echo "abcd contains abcd"
contains "" "" && echo "empty string contains empty string"
contains "a" "" && echo "a contains empty string"
contains "" "a" || echo "empty string does not contain a"
contains "abcd efgh" "cd ef" && echo "abcd efgh contains cd ef"
contains "abcd efgh" " " && echo "abcd efgh contains a space"

JavaScript: Class.method vs. Class.prototype.method

Yes, the first one is a static method also called class method, while the second one is an instance method.

Consider the following examples, to understand it in more detail.

In ES5

function Person(firstName, lastName) {
   this.firstName = firstName;
   this.lastName = lastName;

Person.isPerson = function(obj) {
   return obj.constructor === Person;

Person.prototype.sayHi = function() {
   return "Hi " + this.firstName;

In the above code, isPerson is a static method, while sayHi is an instance method of Person.

Below, is how to create an object from Person constructor.

var aminu = new Person("Aminu", "Abubakar");

Using the static method isPerson.

Person.isPerson(aminu); // will return true

Using the instance method sayHi.

aminu.sayHi(); // will return "Hi Aminu"

In ES6

class Person {
   constructor(firstName, lastName) {
      this.firstName = firstName;
      this.lastName = lastName;

   static isPerson(obj) {
      return obj.constructor === Person;

   sayHi() {
      return `Hi ${this.firstName}`;

Look at how static keyword was used to declare the static method isPerson.

To create an object of Person class.

const aminu = new Person("Aminu", "Abubakar");

Using the static method isPerson.

Person.isPerson(aminu); // will return true

Using the instance method sayHi.

aminu.sayHi(); // will return "Hi Aminu"

NOTE: Both examples are essentially the same, JavaScript remains a classless language. The class introduced in ES6 is primarily a syntactical sugar over the existing prototype-based inheritance model.

ASP.NET MVC - passing parameters to the controller

you can change firstItem to id and it will work

you can change the routing on global.asax (i do not recommed that)

and, can't believe no one mentioned this, you can call :


In a @Url.Action would be :

@Url.Action("ViewStockNext", "Inventory", new {firstItem=11});

depending on the type of what you are doing, the last will be more suitable. Also you should consider not doing ViewStockNext action and instead a ViewStock action with index. (my 2cents)

The application may be doing too much work on its main thread

taken from : Android UI : Fixing skipped frames

Anyone who begins developing android application sees this message on logcat “Choreographer(abc): Skipped xx frames! The application may be doing too much work on its main thread.” So what does it actually means, why should you be concerned and how to solve it.

What this means is that your code is taking long to process and frames are being skipped because of it, It maybe because of some heavy processing that you are doing at the heart of your application or DB access or any other thing which causes the thread to stop for a while.

Here is a more detailed explanation:

Choreographer lets apps to connect themselves to the vsync, and properly time things to improve performance.

Android view animations internally uses Choreographer for the same purpose: to properly time the animations and possibly improve performance.

Since Choreographer is told about every vsync events, I can tell if one of the Runnables passed along by the* apis doesnt finish in one frame’s time, causing frames to be skipped.

In my understanding Choreographer can only detect the frame skipping. It has no way of telling why this happens.

The message “The application may be doing too much work on its main thread.” could be misleading.

source : Meaning of Choreographer messages in Logcat

Why you should be concerned

When this message pops up on android emulator and the number of frames skipped are fairly small (<100) then you can take a safe bet of the emulator being slow – which happens almost all the times. But if the number of frames skipped and large and in the order of 300+ then there can be some serious trouble with your code. Android devices come in a vast array of hardware unlike ios and windows devices. The RAM and CPU varies and if you want a reasonable performance and user experience on all the devices then you need to fix this thing. When frames are skipped the UI is slow and laggy, which is not a desirable user experience.

How to fix it

Fixing this requires identifying nodes where there is or possibly can happen long duration of processing. The best way is to do all the processing no matter how small or big in a thread separate from main UI thread. So be it accessing data form SQLite Database or doing some hardcore maths or simply sorting an array – Do it in a different thread

Now there is a catch here, You will create a new Thread for doing these operations and when you run your application, it will crash saying “Only the original thread that created a view hierarchy can touch its views“. You need to know this fact that UI in android can be changed by the main thread or the UI thread only. Any other thread which attempts to do so, fails and crashes with this error. What you need to do is create a new Runnable inside runOnUiThread and inside this runnable you should do all the operations involving the UI. Find an example here.

So we have Thread and Runnable for processing data out of main Thread, what else? There is AsyncTask in android which enables doing long time processes on the UI thread. This is the most useful when you applications are data driven or web api driven or use complex UI’s like those build using Canvas. The power of AsyncTask is that is allows doing things in background and once you are done doing the processing, you can simply do the required actions on UI without causing any lagging effect. This is possible because the AsyncTask derives itself from Activity’s UI thread – all the operations you do on UI via AsyncTask are done is a different thread from the main UI thread, No hindrance to user interaction.

So this is what you need to know for making smooth android applications and as far I know every beginner gets this message on his console.

How do I remove files saying "old mode 100755 new mode 100644" from unstaged changes in Git?

That looks like unix file permissions modes to me (755=rwxr-xr-x, 644=rw-r--r--) - the old mode included the +x (executable) flag, the new mode doesn't.

This msysgit issue's replies suggests setting core.filemode to false in order to get rid of the issue:

git config core.filemode false

CSS show div background image on top of other contained elements

How about making the <div id="mainWrapperDivWithBGImage"> as three divs, where the two outside divs hold the rounded corners images, and the middle div simply has a background-color to match the rounded corner images. Then you could simply place the other elements inside the middle div, or:

#outside_left{width:10px; float:left;}
#outside_right{width:10px; float:right;}
#middle{background-color:#color of rnd_crnrs_foo.gif; float:left;}



<div id="mainWrapperDivWithBGImage">
  <div id="outside_left><img src="rnd_crnrs_left.gif" /></div>
  <div id="middle">
    <div id="another_div"><img src="foo.gif" /></div>
  <div id="outside_right><img src="rnd_crnrs_right.gif" /></div>

You may have to do position:relative; and such.

Add leading zeroes/0's to existing Excel values to certain length

I hit this page trying to pad hexadecimal values when I realized that DEC2HEX() provides that very feature for free.

You just need to add a second parameter. For example, tying to turn 12 into 0C
DEC2HEX(12,2) => 0C
DEC2HEX(12,4) => 000C
... and so on

Scanf/Printf double variable C

As far as I read manual pages, scanf says that 'l' length modifier indicates (in case of floating points) that the argument is of type double rather than of type float, so you can have 'lf, le, lg'.

As for printing, officially, the manual says that 'l' applies only to integer types. So it might be not supported on some systems or by some standards. For instance, I get the following error message when compiling with gcc -Wall -Wextra -pedantic

a.c:6:1: warning: ISO C90 does not support the ‘%lf’ gnu_printf format [-Wformat=]

So you may want to doublecheck if your standard supports the syntax.

To conclude, I would say that you read with '%lf' and you print with '%f'.

Can ordered list produce result that looks like 1.1, 1.2, 1.3 (instead of just 1, 2, 3, ...) with css?

The solutions posted here did not work well for me, so I did a mixture of the ones of this question and the following question: Is it possible to create multi-level ordered list in HTML?

/* Numbered lists like 1, 1.1, 2.2.1... */
ol li {display:block;} /* hide original list counter */
ol > li:first-child {counter-reset: item;} /* reset counter */
ol > li {counter-increment: item; position: relative;} /* increment counter */
ol > li:before {content:counters(item, ".") ". "; position: absolute; margin-right: 100%; right: 10px;} /* print counter */



Note: the screenshot, if you wish to see the source code or whatever is from this post:

Remove a fixed prefix/suffix from a string in Bash

$ foo=${string#"$prefix"}
$ foo=${foo%"$suffix"}
$ echo "${foo}"

This is documented in the Shell Parameter Expansion section of the manual:


The word is expanded to produce a pattern and matched according to the rules described below (see Pattern Matching). If the pattern matches the beginning of the expanded value of parameter, then the result of the expansion is the expanded value of parameter with the shortest matching pattern (the # case) or the longest matching pattern (the ## case) deleted. […]


The word is expanded to produce a pattern and matched according to the rules described below (see Pattern Matching). If the pattern matches a trailing portion of the expanded value of parameter, then the result of the expansion is the value of parameter with the shortest matching pattern (the % case) or the longest matching pattern (the %% case) deleted. […]

How do I copy an entire directory of files into an existing directory using Python?

The previous solution has some issue that src may overwrite dst without any notification or exception.

I add a predict_error method to predict errors before copy.copytree mainly base on Cyrille Pontvieux's version.

Using predict_error to predict all errors at first is best, unless you like to see exception raised one by another when execute copytree until fix all error.

def predict_error(src, dst):  
    if os.path.exists(dst):
        src_isdir = os.path.isdir(src)
        dst_isdir = os.path.isdir(dst)
        if src_isdir and dst_isdir:
        elif src_isdir and not dst_isdir:
            yield {dst:'src is dir but dst is file.'}
        elif not src_isdir and dst_isdir:
            yield {dst:'src is file but dst is dir.'}
            yield {dst:'already exists a file with same name in dst'}

    if os.path.isdir(src):
        for item in os.listdir(src):
            s = os.path.join(src, item)
            d = os.path.join(dst, item)
            for e in predict_error(s, d):
                yield e

def copytree(src, dst, symlinks=False, ignore=None, overwrite=False):
    would overwrite if src and dst are both file
    but would not use folder overwrite file, or viceverse
    if not overwrite:
        errors = list(predict_error(src, dst))
        if errors:
            raise Exception('copy would overwrite some file, error detail:%s' % errors)

    if not os.path.exists(dst):
        shutil.copystat(src, dst)
    lst = os.listdir(src)
    if ignore:
        excl = ignore(src, lst)
        lst = [x for x in lst if x not in excl]
    for item in lst:
        s = os.path.join(src, item)
        d = os.path.join(dst, item)
        if symlinks and os.path.islink(s):
            if os.path.lexists(d):
            os.symlink(os.readlink(s), d)
                st = os.lstat(s)
                mode = stat.S_IMODE(st.st_mode)
                os.lchmod(d, mode)
                pass  # lchmod not available
        elif os.path.isdir(s):
            copytree(s, d, symlinks, ignore)
            if not overwrite:
                if os.path.exists(d):
            shutil.copy2(s, d)

Refresh Fragment at reload

   MyFragment fragment = (MyFragment) getSupportFragmentManager().findFragmentByTag(FRAGMENT_TAG);

this will only work if u use FragmentManager to initialize the fragment. If u have it as a <fragment ... /> in XML, it won't call the onCreateView again. Wasted my 30 minutes to figure this out.

MySQL - How to select rows where value is in array?

If the array element is not integer you can use something like below :

$skus  = array('LDRES10','LDRES12','LDRES11');   //sample data

    $sql = "SELECT * FROM `products` WHERE `prodCode` IN ('" . implode("','", $skus) . "') "      

Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop

Same answer as Claudius with a for loop:

for (Iterator<Object> it = objects.iterator(); it.hasNext();) {
    Object object =;
    if (test) {

java.text.ParseException: Unparseable date

Update your format to:

SimpleDateFormat sdf=new SimpleDateFormat("E MMM dd hh:mm:ss Z yyyy");

How to get the date and time values in a C program?

instead of files use pipes and if u wana use C and not C++ u can use popen like this


FILE *fp= popen("date +F","r");

and use *fp as a normal file pointer with fgets and all

if u wana use c++ strings, fork a child, invoke the command and then pipe it to the parent.

   #include <stdlib.h>
   #include <iostream>
   #include <string>
   using namespace std;

   string currentday;
   int dependPipe[2];

   pipe(dependPipe);// make the pipe

           dup2(dependPipe[0],0);//convert parent's std input to pipe's output

    } else {//child
        dup2(dependPipe[1],1);//convert child's std output to pipe's input

        system("date +%F");

// make a similar 1 for date +T but really i recommend u stick with stuff in time.h GL

How to sort a List<Object> alphabetically using Object name field

Using Java 8 Comparator.comparing:


How can I tell if a DOM element is visible in the current viewport?

Now most browsers support getBoundingClientRect method, which has become the best practice. Using an old answer is very slow, not accurate and has several bugs.

The solution selected as correct is almost never precise. You can read more about its bugs.

This solution was tested on Internet Explorer 7 (and later), iOS 5 (and later) Safari, Android 2.0 (Eclair) and later, BlackBerry, Opera Mobile, and Internet Explorer Mobile 9.

function isElementInViewport (el) {

    // Special bonus for those using jQuery
    if (typeof jQuery === "function" && el instanceof jQuery) {
        el = el[0];

    var rect = el.getBoundingClientRect();

    return ( >= 0 &&
        rect.left >= 0 &&
        rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && /* or $(window).height() */
        rect.right <= (window.innerWidth || document.documentElement.clientWidth) /* or $(window).width() */

How to use:

You can be sure that the function given above returns correct answer at the moment of time when it is called, but what about tracking element's visibility as an event?

Place the following code at the bottom of your <body> tag:

function onVisibilityChange(el, callback) {
    var old_visible;
    return function () {
        var visible = isElementInViewport(el);
        if (visible != old_visible) {
            old_visible = visible;
            if (typeof callback == 'function') {

var handler = onVisibilityChange(el, function() {
    /* Your code go here */

// jQuery
$(window).on('DOMContentLoaded load resize scroll', handler);

/* // Non-jQuery
if (window.addEventListener) {
    addEventListener('DOMContentLoaded', handler, false);
    addEventListener('load', handler, false);
    addEventListener('scroll', handler, false);
    addEventListener('resize', handler, false);
} else if (window.attachEvent)  {
    attachEvent('onDOMContentLoaded', handler); // Internet Explorer 9+ :(
    attachEvent('onload', handler);
    attachEvent('onscroll', handler);
    attachEvent('onresize', handler);

If you do any DOM modifications, they can change your element's visibility of course.

Guidelines and common pitfalls:

Maybe you need to track page zoom / mobile device pinch? jQuery should handle zoom/pinch cross browser, otherwise first or second link should help you.

If you modify DOM, it can affect the element's visibility. You should take control over that and call handler() manually. Unfortunately, we don't have any cross browser onrepaint event. On the other hand that allows us to make optimizations and perform re-check only on DOM modifications that can change an element's visibility.

Never Ever use it inside jQuery $(document).ready() only, because there is no warranty CSS has been applied in this moment. Your code can work locally with your CSS on a hard drive, but once put on a remote server it will fail.

After DOMContentLoaded is fired, styles are applied, but the images are not loaded yet. So, we should add window.onload event listener.

We can't catch zoom/pinch event yet.

The last resort could be the following code:

/* TODO: this looks like a very bad code */
setInterval(handler, 600);

You can use the awesome feature pageVisibiliy of the HTML5 API if you care if the tab with your web page is active and visible.

TODO: this method does not handle two situations:

How do you disable viewport zooming on Mobile Safari?

@mattis is correct that iOS 10 Safari won't allow you to disable pinch to zoom with the user-scalable attribute. However, I got it to disable using preventDefault on the 'gesturestart' event. I've only verified this on Safari in iOS 10.0.2.

document.addEventListener('gesturestart', function (e) {

Ruby: How to turn a hash into HTTP parameters?

2.6.3 :001 > hash = {:a => "a", :b => ["c", "d", "e"]}
=> {:a=>"a", :b=>["c", "d", "e"]}
2.6.3 :002 > { |x| "#{x[0]}=#{x[1].class == Array ? x[1].join(",") : x[1]}" 
=> "a=a&b=c,d,e"

Use string.Contains() with switch()

Stegmenn nalied it for me but I had one change for when you have an IEnumerbale instead of a string = message like in his example.

private static string GetRoles(IEnumerable<External.Role> roles)
            string[] switchStrings = { "Staff", "Board Member" };
            switch (switchStrings.FirstOrDefault<string>(s => roles.Select(t => t.RoleName).Contains(s)))
                    roleNameValues += "Staff,";
                    "Board Member":
                    roleNameValues += "Director,";

Plotting a 3d cube, a sphere and a vector in Matplotlib

My answer is an amalgamation of the above two with extension to drawing sphere of user-defined opacity and some annotation. It finds application in b-vector visualization on a sphere for magnetic resonance image (MRI). Hope you find it useful:

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.gca(projection='3d')

# draw sphere
u, v = np.mgrid[0:2*np.pi:50j, 0:np.pi:50j]
x = np.cos(u)*np.sin(v)
y = np.sin(u)*np.sin(v)
z = np.cos(v)
# alpha controls opacity
ax.plot_surface(x, y, z, color="g", alpha=0.3)

# a random array of 3D coordinates in [-1,1]
bvecs= np.random.randn(20,3)

# tails of the arrows
tails= np.zeros(len(bvecs))

# heads of the arrows with adjusted arrow head length
ax.quiver(tails,tails,tails,bvecs[:,0], bvecs[:,1], bvecs[:,2],
          length=1.0, normalize=True, color='r', arrow_length_ratio=0.15)


ax.set_title('b-vectors on unit sphere')

How to loop through array in jQuery?

  for(var key in substr)
     // do something with substr[key];


Android: How can I pass parameters to AsyncTask's onPreExecute()?

1) For me that's the most simple way passing parameters to async task is like this

// To call the async task do it like this
Boolean[] myTaskParams = { true, true, true };
myAsyncTask = new myAsyncTask ().execute(myTaskParams);

Declare and use the async task like here

private class myAsyncTask extends AsyncTask<Boolean, Void, Void> {

    protected Void doInBackground(Boolean...pParams) 
        Boolean param1, param2, param3;



2) Passing methods to async-task In order to avoid coding the async-Task infrastructure (thread, messagenhandler, ...) multiple times you might consider to pass the methods which should be executed in your async-task as a parameter. Following example outlines this approach. In addition you might have the need to subclass the async-task to pass initialization parameters in the constructor.

 /* Generic Async Task    */
interface MyGenericMethod {
    int execute(String param);

protected class testtask extends AsyncTask<MyGenericMethod, Void, Void>
    public String mParam;                           // member variable to parameterize the function
    protected Void doInBackground(MyGenericMethod... params) {
        //  do something here
        return null;

// to start the asynctask do something like that
public void startAsyncTask()
    AsyncTask<MyGenericMethod, Void, Void>  mytest = new testtask().execute(new MyGenericMethod() {
        public int execute(String param) {
            return 1;

Dropdownlist validation in Using Required field validator

Add InitialValue="0" in Required field validator tag

 <asp:RequiredFieldValidator InitialValue="-1" ID="Req_ID"
      Display="Dynamic" ValidationGroup="g1" runat="server"
      InitialValue="0" ErrorMessage="ErrorMessage">

Configure DataSource programmatically in Spring Boot

If you're using latest spring boot (with jdbc starter and Hikari) you'll run into: java.lang.IllegalArgumentException: jdbcUrl is required with driverClassName. To solve this:

  1. In your

  1. In your application define as bean (@Primary is mandatory!):
public DataSourceProperties getDatasourceProperties() {
    return new DataSourceProperties();

public DataSource getDatasource() {
    return getDatasourceProperties().initializeDataSourceBuilder()

How to correctly close a feature branch in Mercurial?

imho there are two cases for branches that were forgot to close

Case 1: branch was not merged into default

in this case I update to the branch and do another commit with --close-branch, unfortunatly this elects the branch to become the new tip and hence before pushing it to other clones I make sure that the real tip receives some more changes and others don't get confused about that strange tip.

hg up myBranch
hg commit --close-branch

Case 2: branch was merged into default

This case is not that much different from case 1 and it can be solved by reproducing the steps for case 1 and two additional ones.

in this case I update to the branch changeset, do another commit with --close-branch and merge the new changeset that became the tip into default. the last operation creates a new tip that is in the default branch - HOORAY!

hg up myBranch
hg commit --close-branch
hg up default
hg merge myBranch

Hope this helps future readers.

Docker compose, running containers in net:host

Maybe I am answering very late. But I was also having a problem configuring host network in docker compose. Then I read the documentation thoroughly and made the changes and it worked. Please note this configuration is for docker-compose version "3.7". Here einwohner_net and elk_net_net are my user-defined networks required for my application. I am using host net to get some system metrics.

Link To Documentation

version: '3.7'
    image: ramansharma/einwohnertomcat:v0.0.1
      replicas: 1
       - '8080:8080'
     - type: bind
       source: /proc
       target: /hostfs/proc
       read_only: true
     - type: bind
       source: /sys/fs/cgroup
       target: /hostfs/sys/fs/cgroup
       read_only: true
     - type: bind
       source: /
       target: /hostfs
       read_only: true
     hostnet: {}
     - einwohner_net
     - elk_elk_net
   external: true
   external: true
   name: host

What's the most efficient way to check if a record exists in Oracle?

select case 
            when exists (select 1 
                         from sales 
                         where sales_type = 'Accessories') 
            then 'Y' 
            else 'N' 
        end as rec_exists
from dual;

using where and inner join in mysql

    SELECT `locations`.`name`
      FROM `locations`
INNER JOIN `school_locations`
        ON `locations`.`id` = `school_locations`.`location_id`
INNER JOIN `schools`
        ON `school_locations`.`school_id` = `schools_id`
     WHERE `type` = 'coun';

the WHERE clause has to be at the end of the statement

Using a custom (ttf) font in CSS

You need to use the css-property font-face to declare your font. Have a look at this fancy site:


@font-face {
  font-family: MyHelvetica;
  src: local("Helvetica Neue Bold"),
  font-weight: bold;

See also: MDN @font-face

jQuery append() and remove() element

You can call a reset function before appending. Something like this:

    function resetNewReviewBoardForm() {
    $("#members").empty(); //this one what worked in my case

How do I set bold and italic on UILabel of iPhone/iPad?

Good answers here, but if you want the label respects the user's preferred size category, use preferredFont.

UIFont.systemFont(ofSize: UIFont.preferredFont(forTextStyle: .body).pointSize, weight: .bold)

Where does Jenkins store configuration files for the jobs it runs?

Am adding few things related to jenkins configuration files storage.

As per my understanding all config file stores in the machine or OS that you have installed jenkins.

The jobs you are going to create in jenkins will be stored in jenkins server and you can find the config.xml etc., here.

After jenkins installation you will find jenkins workspace in server.

   job1 job2 job3 config.xml ....*

XML Error: There are multiple root elements

Wrap the xml in another element


How to change indentation mode in Atom?

Changing language-specific configuration

I changed the default tab settings, and it still did not impact when I was editing my files, which were Python files. It also did not change when I modified the "*" setting in ~/.atom/config.cson . I don't have a good explanation for either of those.

However, when I added the following to my config.cson, I was able to change the tab in my Python files to 2 spaces:

    tabLength: 2

Thanks to this resource for the solution: Tab key not respecting tab length

How to clean project cache in Intellij idea like Eclipse's clean?

If you are using Maven, run this command in your project directory

mvn clean package

using jquery $.ajax to call a PHP function

You may use my library that does that automatically, I've been improving it for the past 2 years

   'phpfunction' => function($data){
      /* Do your thing */
      return PheryResponse::factory(); // do your dom manipulation, return JSON, etc

The javascript would be simple as


You can pass all the dynamic javascript part to the server, with a query builder like chainable interface, and you may pass any type of data back to the PHP. For example, some functions that would take too much space in the javascript side, could be called in the server using this (in this example, mcrypt, that in javascript would be almost impossible to accomplish):

function mcrypt(variable, content, key){
  phery.remote('mcrypt_encrypt', {'var': variable, 'content': content, 'key':key || false});

//would use it like (you may keep the key on the server, safer, unless it's encrypted for the user)
window.variable = '';
mcrypt('variable', 'This must be encoded and put inside variable', 'my key');

and in the server

  'mcrypt_encrypt' => function($data){
     $r = new PheryResponse;

     $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
     $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
     $encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $data['key'] ? : 'my key', $data['content'], MCRYPT_MODE_ECB, $iv);
     return $r->set_var($data['variable'], $encrypted);
     // or call a callback with the data, $r->call($data['callback'], $encrypted);

Now the variable will have the encrypted data.

Get current scroll position of ScrollView in React Native

I believe contentOffset will give you an object containing the top-left scroll offset:

How do I get the first element from an IEnumerable<T> in .net?

Use FirstOrDefault or a foreach loop as already mentioned. Manually fetching an enumerator and calling Current should be avoided. foreach will dispose your enumerator for you if it implements IDisposable. When calling MoveNext and Current you have to dispose it manually (if aplicable).

Get first row of dataframe in Python Pandas based on criteria

For the point that 'returns the value as soon as you find the first row/record that meets the requirements and NOT iterating other rows', the following code would work:

def pd_iter_func(df):
    for row in df.itertuples():
        # Define your criteria here
        if row.A > 4 and row.B > 3:
            return row

It is more efficient than Boolean Indexing when it comes to a large dataframe.

To make the function above more applicable, one can implements lambda functions:

def pd_iter_func(df: DataFrame, criteria: Callable[[NamedTuple], bool]) -> Optional[NamedTuple]:
    for row in df.itertuples():
        if criteria(row):
            return row

pd_iter_func(df, lambda row: row.A > 4 and row.B > 3)

As mentioned in the answer to the 'mirror' question, pandas.Series.idxmax would also be a nice choice.

def pd_idxmax_func(df, mask):
    return df.loc[mask.idxmax()]

pd_idxmax_func(df, (df.A > 4) & (df.B > 3))

How to add a button programmatically in VBA next to some sheet cell data?

Suppose your function enters data in columns A and B and you want to a custom Userform to appear if the user selects a cell in column C. One way to do this is to use the SelectionChange event:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim clickRng As Range
    Dim lastRow As Long

    lastRow = Range("A1").End(xlDown).Row
    Set clickRng = Range("C1:C" & lastRow) //Dynamically set cells that can be clicked based on data in column A

    If Not Intersect(Target, clickRng) Is Nothing Then
        MyUserForm.Show //Launch custom userform
    End If

End Sub

Note that the userform will appear when a user selects any cell in Column C and you might want to populate each cell in Column C with something like "select cell to launch form" to make it obvious that the user needs to perform an action (having a button naturally suggests that it should be clicked)

cancelling a handler.postdelayed process

In case you do have multiple inner/anonymous runnables passed to same handler, and you want to cancel all at same event use


As per documentation,

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

How to set background color of view transparent in React Native

You should be aware of the current conflicts that exists with iOS and RGBA backgrounds.

Summary: public React Native currently exposes the iOS layer shadow properties more-or-less directly, however there are a number of problems with this:

1) Performance when using these properties is poor by default. That's because iOS calculates the shadow by getting the exact pixel mask of the view, including any tranlucent content, and all of its subviews, which is very CPU and GPU-intensive. 2) The iOS shadow properties do not match the syntax or semantics of the CSS box-shadow standard, and are unlikely to be possible to implement on Android. 3) We don't expose the layer.shadowPath property, which is crucial to getting good performance out of layer shadows.

This diff solves problem number 1) by implementing a default shadowPath that matches the view border for views with an opaque background. This improves the performance of shadows by optimizing for the common usage case. I've also reinstated background color propagation for views which have shadow props - this should help ensure that this best-case scenario occurs more often.

For views with an explicit transparent background, the shadow will continue to work as it did before ( shadowPath will be left unset, and the shadow will be derived exactly from the pixels of the view and its subviews). This is the worst-case path for performance, however, so you should avoid it unless absolutely necessary. Support for this may be disabled by default in future, or dropped altogether.

For translucent images, it is suggested that you bake the shadow into the image itself, or use another mechanism to pre-generate the shadow. For text shadows, you should use the textShadow properties, which work cross-platform and have much better performance.

Problem number 2) will be solved in a future diff, possibly by renaming the iOS shadowXXX properties to boxShadowXXX, and changing the syntax and semantics to match the CSS standards.

Problem number 3) is now mostly moot, since we generate the shadowPath automatically. In future, we may provide an iOS-specific prop to set the path explicitly if there's a demand for more precise control of the shadow.

Reviewed By: weicool


Group query results by month and year in postgresql

to_char actually lets you pull out the Year and month in one fell swoop!

select to_char(date('2014-05-10'),'Mon-YY') as year_month; --'May-14'
select to_char(date('2014-05-10'),'YYYY-MM') as year_month; --'2014-05'

or in the case of the user's example above:

select to_char(date,'YY-Mon') as year_month
       sum("Sales") as "Sales"
from some_table
group by 1;

Should I URL-encode POST data?

@DougW has clearly answered this question, but I still like to add some codes here to explain Doug's points. (And correct errors in the code above)

Solution 1: URL-encode the POST data with a content-type header :application/x-www-form-urlencoded .

Note: you do not need to urlencode $_POST[] fields one by one, http_build_query() function can do the urlencoding job nicely.

$fields = array(

$fields_string = http_build_query($fields);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_POSTFIELDS,$fields_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($ch);

Solution 2: Pass the array directly as the post data without URL-encoding, while the Content-Type header will be set to multipart/form-data.

$fields = array(

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL,$url);
    curl_setopt($ch, CURLOPT_POST,1);
    curl_setopt($ch, CURLOPT_POSTFIELDS,$fields);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $response = curl_exec($ch);

Both code snippets work, but using different HTTP headers and bodies.

How to read and write xml files?

SAX parser is working differently with a DOM parser, it neither load any XML document into memory nor create any object representation of the XML document. Instead, the SAX parser use callback function org.xml.sax.helpers.DefaultHandler to informs clients of the XML document structure.

SAX Parser is faster and uses less memory than DOM parser. See following SAX callback methods :

startDocument() and endDocument() – Method called at the start and end of an XML document. startElement() and endElement() – Method called at the start and end of a document element. characters() – Method called with the text contents in between the start and end tags of an XML document element.

  1. XML file

Create a simple XML file.

<?xml version="1.0"?>
        <lastname>mook kim</lastname>
        <lastname>yin fong</lastname>
        <nickname>fong fong</nickname>
  1. XML parser:

Java file Use SAX parser to parse the XML file.

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class ReadXMLFile {
    public static void main(String argv[]) {

        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();

            DefaultHandler handler = new DefaultHandler() {
                boolean bfname = false;
                boolean blname = false;
                boolean bnname = false;
                boolean bsalary = false;

                public void startElement(String uri, String localName,String qName, 
                            Attributes attributes) throws SAXException {

                    System.out.println("Start Element :" + qName);

                    if (qName.equalsIgnoreCase("FIRSTNAME")) {
                        bfname = true;

                    if (qName.equalsIgnoreCase("LASTNAME")) {
                        blname = true;

                    if (qName.equalsIgnoreCase("NICKNAME")) {
                        bnname = true;

                    if (qName.equalsIgnoreCase("SALARY")) {
                        bsalary = true;


                public void endElement(String uri, String localName,
                    String qName) throws SAXException {

                    System.out.println("End Element :" + qName);


                public void characters(char ch[], int start, int length) throws SAXException {

                    if (bfname) {
                        System.out.println("First Name : " + new String(ch, start, length));
                        bfname = false;

                    if (blname) {
                        System.out.println("Last Name : " + new String(ch, start, length));
                        blname = false;

                    if (bnname) {
                        System.out.println("Nick Name : " + new String(ch, start, length));
                        bnname = false;

                    if (bsalary) {
                        System.out.println("Salary : " + new String(ch, start, length));
                        bsalary = false;



            saxParser.parse("c:\\file.xml", handler);

        } catch (Exception e) {




Start Element :company
Start Element :staff
Start Element :firstname
First Name : yong
End Element :firstname
Start Element :lastname
Last Name : mook kim
End Element :lastname
Start Element :nickname
Nick Name : mkyong
End Element :nickname
and so on...

Source(MyKong) -

Is it possible to use Visual Studio on macOS?

Yes, you can! There's a Visual Studio for macs and there's Visual Studio Code if you only need a text editor like Sublime Text.

JavaScript: Create and destroy class instance through class method

You can only manually delete properties of objects. Thus:

var container = {};

container.instance = new class();

delete container.instance;

However, this won't work on any other pointers. Therefore:

var container = {};

container.instance = new class();

var pointer = container.instance;

delete pointer; // false ( ie attempt to delete failed )


delete container.instance; // true ( ie attempt to delete succeeded, but... )

pointer; // class { destroy: function(){} }

So in practice, deletion is only useful for removing object properties themselves, and is not a reliable method for removing the code they point to from memory.

A manually specified destroy method could unbind any event listeners. Something like:

function class(){ = { /**/ }

  function handler(){ /**/ }

  something.addEventListener( 'event', handler, false );

  this.destroy = function(){
    something.removeEventListener( 'event', handler );

How do I change the font size and color in an Excel Drop Down List?

Try making the whole sheet font size smaller. Then zoom and save. Make a practice sheet first because it really screws everything up.

Excel error HRESULT: 0x800A03EC while trying to get range with cell's name

I had this problem when I was trying to use the range.AddComment() function. I was able to solve this by calling range.ClearComment() before adding the comment.

How can I permanently enable line numbers in IntelliJ?

Android Studio 1.3.2 and on, IntelliJ 15 and on

Global configuration

File -> Settings -> Editor -> General -> Appearance -> Show line numbers

enter image description here

Current editor configuration

First way: View -> Active Editor -> Show Line Numbers (this option will only be available if you previously have clicked into a file of the active editor)

Second way: Right click on the small area between the project's structure and the active editor (that is, the one that you can set breakpoints) -> Show Line Numbers. enter image description here

How to add parameters to an external data query in Excel which can't be displayed graphically?

YES - solution is to save workbook in to XML file (eg. 'XML Spreadsheet 2003') and edit this file as text in notepad! use "SEARCH" function of notepad to find query text and change your data to "?".

save and open in excel, try refresh data and excel will be monit about parameters.

How to set OnClickListener on a RadioButton in Android?

I'd think a better way is to use RadioGroup and set the listener on this to change and update the View accordingly (saves you having 2 or 3 or 4 etc listeners).

    RadioGroup radioGroup = (RadioGroup) findViewById(;        
    radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() 
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            // checkedId is the RadioButton selected

error: could not create '/usr/local/lib/python2.7/dist-packages/virtualenv_support': Permission denied

In the case of permission denied error, you just need to go with this command.

sudo pip install virtualenv

sudo before the command will throw away the current user permissions error.

Note: For security risks, You should read piotr comment.

Tomcat 8 is not able to handle get request with '|' in query parameters?

Since Tomcat 7.0.76, 8.0.42, 8.5.12 you can define property requestTargetAllow to allow forbiden characters.

Add this line in your


HttpContext.Current.Session is null when routing requests

What @Bogdan Maxim said. Or change to use InProc if you're not using an external sesssion state server.

<sessionState mode="InProc" timeout="20" cookieless="AutoDetect" />

Look here for more info on the SessionState directive.

Difference between Convert.ToString() and .ToString()

ToString() Vs Convert.ToString()

Similarities :-

Both are used to convert a specific type to string i.e int to string, float to string or an object to string.

Difference :-

ToString() can't handle null while in case with Convert.ToString() will handle null value.

Example :

namespace Marcus
    class Employee
        public int Id { get; set; }
        public string Name { get; set; }
    class Startup
        public static void Main()
            Employee e = new Employee();
            e = null;

            string s = e.ToString(); // This will throw an null exception
            s = Convert.ToString(e); // This will throw null exception but it will be automatically handled by Convert.ToString() and exception will not be shown on command window.

CSS background image URL failing to load

I know this is really old, but I'm posting my solution anyways since google finds this thread.

background-image: url('./imagefolder/image.jpg');

That is what I do. Two dots means drill back one directory closer to root ".." while one "." should mean start where you are at as if it were root. I was having similar issues but adding that fixed it for me. You can even leave the "." in it when uploading to your host because it should work fine so long as your directory setup is exactly the same.

Debug/run standard java in Visual Studio Code IDE and OS X?

Code Runner Extension will only let you "run" java files.

To truly debug 'Java' files follow the quick one-time setup:

  • Install Java Debugger Extension in VS Code and reload.
  • open an empty folder/project in VS code.
  • create your java file (s).
  • create a folder .vscode in the same folder.
  • create 2 files inside .vscode folder: tasks.json and launch.json
  • copy paste below config in tasks.json:
    "version": "2.0.0",
    "type": "shell",
    "presentation": {
        "echo": true,
        "reveal": "always",
        "focus": false,
        "panel": "shared"
    "isBackground": true,
    "tasks": [
            "taskName": "build",
            "args": ["-g", "${file}"],
            "command": "javac"
  • copy paste below config in launch.json:
    "version": "0.2.0",
    "configurations": [
            "name": "Debug Java",
            "type": "java",
            "request": "launch",
            "externalConsole": true,                //user input dosen't work if set it to false :(
            "stopOnEntry": true,
            "preLaunchTask": "build",                 // Runs the task created above before running this configuration
            "jdkPath": "${env:JAVA_HOME}/bin",        // You need to set JAVA_HOME enviroment variable
            "cwd": "${workspaceRoot}",
            "startupClass": "${workspaceRoot}${file}",
            "sourcePath": ["${workspaceRoot}"],   // Indicates where your source (.java) files are
            "classpath": ["${workspaceRoot}"],    // Indicates the location of your .class files
            "options": [],                             // Additional options to pass to the java executable
            "args": []                                // Command line arguments to pass to the startup class

    "compounds": []

You are all set to debug java files, open any java file and press F5 (Debug->Start Debugging).

Tip: *To hide .class files in the side explorer of VS code, open settings of VS code and paste the below config:

"files.exclude": {
        "*.class": true

enter image description here

What is the minimum length of a valid international phone number?

EDIT 2015-06-27: Minimum is actually 8, including country code. My bad.

Original post

The minimum phone number that I use is 10 digits. International users should always be putting their country code, and as far as I know there are no countries with fewer than ten digits if you count country code.

More info here:

Prime numbers between 1 to 100 in C Programming Language

#include <stdio.h>

int main () {

   int i, j;

   for(i = 2; i<100; i++) {

      for(j = 2; j <= (i/j); j++) 
      if(!(i%j)) break; // if factor found, not prime
      if(j > (i/j)) printf("%d is prime", i);

   return 0;

Where should my npm modules be installed on Mac OS X?

/usr/local/lib/node_modules is the correct directory for globally installed node modules.

/usr/local/share/npm/lib/node_modules makes no sense to me. One issue here is that you're confused because there are two directories called node_modules:


The latter seems to be node modules that came with Node, e.g., lodash, when the former is Node modules that I installed using npm.

Laravel 5 Eloquent where and or in Clauses

Also, if you have a variable,

CabRes::where('m_Id', 46)
      ->where('t_Id', 2)
      ->where(function($q) use ($variable){
          $q->where('Cab', 2)
            ->orWhere('Cab', $variable);

How to: Create trigger for auto update modified date with SQL Server 2008

My approach:

  • define a default constraint on the ModDate column with a value of GETDATE() - this handles the INSERT case

  • have a AFTER UPDATE trigger to update the ModDate column

Something like:

CREATE TRIGGER trg_UpdateTimeEntry
ON dbo.TimeEntry
    UPDATE dbo.TimeEntry
    SET ModDate = GETDATE()

Windows ignores JAVA_HOME: how to set JDK as default?

For my Case in 'Path' variable there was a parameter added like 'C:\ProgramData\Oracle\Java\javapath;'. This location was having java.exe, javaw.exe and javaws.exe from java 8 which is newly installed via jdk.exe from Oracle.

I've removed this text from Path where my Path already having %JAVA_HOME%\bin with it.

Now, the variable 'JAVA_HOME' is controlling my Java version which is I wanted.

Git - push current branch shortcut

I use such alias in my .bashrc config

alias gpb='git push origin `git rev-parse --abbrev-ref HEAD`'

On the command $gpb it takes the current branch name and pushes it to the origin.

Here are my other aliases:

alias gst='git status'
alias gbr='git branch'
alias gca='git commit -am'
alias gco='git checkout'

iPhone Safari Web App opens links in new window

I've found one that is very complete and efficient because it checks to be running only under standalone WebApp, works without jQuery and is also straightforward, just tested under iOS 8.2 :

Stay Standalone: Prevent links in standalone web apps opening Mobile Safari

How to copy a directory structure but only include certain files (using windows batch files)

An alternate solution that copies one file at a time and does not require ROBOCOPY:

@echo off
setlocal enabledelayedexpansion

set "SOURCE_DIR=C:\Source"
set "DEST_DIR=C:\Destination"
set info.txt

    if exist "%%F" (
        set FILE_DIR=%%~dpF
        xcopy /E /I /Y "%%F" "%DEST_DIR%!FILE_INTERMEDIATE_DIR!"

The outer for statement generates any possible path combination of subdirectory in SOURCE_DIR and name in FILENAMES_TO_COPY. For each existing file xcopy is invoked. FILE_INTERMEDIATE_DIR holds the file's subdirectory path within SOURCE_DIR which needs to be created in DEST_DIR.

Better way to find last used row

I use this routine to find the count of data rows. There is a minimum of overhead required, but by counting using a decreasing scale, even a very large result requires few iterations. For example, a result of 28,395 would only require 2 + 8 + 3 + 9 + 5, or 27 times through the loop, instead of a time-expensive 28,395 times.

Even were we to multiply that by 10 (283,950), the iteration count is the same 27 times.

Dim lWorksheetRecordCountScaler as Long
Dim lWorksheetRecordCount as Long

Const sDataColumn = "A"   '<----Set to column that has data in all rows (Code, ID, etc.)

    'Count the data records
    lWorksheetRecordCountScaler = 100000  'Begin by counting in 100,000-record bites
    lWorksheetRecordCount = lWorksheetRecordCountScaler

    While lWorksheetRecordCountScaler >= 1

        While Sheets("Sheet2").Range(sDataColumn & lWorksheetRecordCount + 2).Formula > " "
            lWorksheetRecordCount = lWorksheetRecordCount + lWorksheetRecordCountScaler

        'To the beginning of the previous bite, count 1/10th of the scale from there
        lWorksheetRecordCount = lWorksheetRecordCount - lWorksheetRecordCountScaler
        lWorksheetRecordCountScaler = lWorksheetRecordCountScaler / 10


    lWorksheetRecordCount = lWorksheetRecordCount + 1   'Final answer

What is "with (nolock)" in SQL Server?

Short answer:

Only use WITH (NOLOCK) in SELECT statement on tables that have a clustered index.

Long answer:

WITH(NOLOCK) is often exploited as a magic way to speed up database reads.

The result set can contain rows that have not yet been committed, that are often later rolled back.

If WITH(NOLOCK) is applied to a table that has a non-clustered index then row-indexes can be changed by other transactions as the row data is being streamed into the result-table. This means that the result-set can be missing rows or display the same row multiple times.

READ COMMITTED adds an additional issue where data is corrupted within a single column where multiple users change the same cell simultaneously.

Detect IE version (prior to v9) in JavaScript

Return IE version or if not IE return false

function isIE () {
  var myNav = navigator.userAgent.toLowerCase();
  return (myNav.indexOf('msie') != -1) ? parseInt(myNav.split('msie')[1]) : false;


if (isIE () == 8) {
 // IE8 code
} else {
 // Other versions IE or not IE


if (isIE () && isIE () < 9) {
 // is IE version less than 9
} else {
 // is IE 9 and later or not IE


if (isIE()) {
 // is IE
} else {
 // Other browser

react-native - Fit Image in containing View, not the whole screen size

If you know the aspect ratio for example, if your image is square you can set either the height or the width to fill the container and get the other to be set by the aspectRatio property

Here is the style if you want the height be set automatically:

    width: '100%',
    height: undefined,
    aspectRatio: 1,

Note: height must be undefined

Reference — What does this symbol mean in PHP?

Nullable return type declaration

PHP 7 adds support for return type declarations. Similarly to argument type declarations, return type declarations specify the type of value that will be returned from a function. The same types are available for return type declarations as are available for argument type declarations.

Strict typing also has an effect on return type declarations. In the default weak mode, returned values will be coerced to the correct type if they are not already of that type. In strong mode, the returned value must be of the correct type, otherwise, a TypeError will be thrown.

As of PHP 7.1.0, return values can be marked as nullable by prefixing the type name with a question mark (?). This signifies that the function returns either the specified type or NULL.

function get_item(): ?string {
    if (isset($_GET['item'])) {
        return $_GET['item'];
    } else {
        return null;


Order of execution of tests in TestNG

Tests like unit tests? What for? Tests HAVE to be independant, otherwise.... you can not run a test individually. If they are independent, why even interfere? Plus - what is an "order" if you run them in multiple threads on multiple cores?

How can I get the client's IP address in ASP.NET MVC?

A lot of the code here was very helpful, but I cleaned it up for my purposes and added some tests. Here's what I ended up with:

using System;
using System.Linq;
using System.Net;
using System.Web;

public class RequestHelpers
    public static string GetClientIpAddress(HttpRequestBase request)
            var userHostAddress = request.UserHostAddress;

            // Attempt to parse.  If it fails, we catch below and return ""
            // Could use TryParse instead, but I wanted to catch all exceptions

            var xForwardedFor = request.ServerVariables["X_FORWARDED_FOR"];

            if (string.IsNullOrEmpty(xForwardedFor))
                return userHostAddress;

            // Get a list of public ip addresses in the X_FORWARDED_FOR variable
            var publicForwardingIps = xForwardedFor.Split(',').Where(ip => !IsPrivateIpAddress(ip)).ToList();

            // If we found any, return the last one, otherwise return the user host address
            return publicForwardingIps.Any() ? publicForwardingIps.Last() : userHostAddress;
        catch (Exception)
            // Always return all zeroes for any failure (my calling code expects it)
            return "";

    private static bool IsPrivateIpAddress(string ipAddress)
        // Private IP Addresses are: 
        //  24-bit block: through
        //  20-bit block: through
        //  16-bit block: through
        //  Link-local addresses: through (

        var ip = IPAddress.Parse(ipAddress);
        var octets = ip.GetAddressBytes();

        var is24BitBlock = octets[0] == 10;
        if (is24BitBlock) return true; // Return to prevent further processing

        var is20BitBlock = octets[0] == 172 && octets[1] >= 16 && octets[1] <= 31;
        if (is20BitBlock) return true; // Return to prevent further processing

        var is16BitBlock = octets[0] == 192 && octets[1] == 168;
        if (is16BitBlock) return true; // Return to prevent further processing

        var isLinkLocalAddress = octets[0] == 169 && octets[1] == 254;
        return isLinkLocalAddress;

And here are some NUnit tests against that code (I'm using Rhino Mocks to mock the HttpRequestBase, which is the M<HttpRequestBase> call below):

using System.Web;
using NUnit.Framework;
using Rhino.Mocks;
using Should;

public class HelpersTests : TestBase
    HttpRequestBase _httpRequest;

    private const string XForwardedFor = "X_FORWARDED_FOR";
    private const string MalformedIpAddress = "MALFORMED";
    private const string DefaultIpAddress = "";
    private const string GoogleIpAddress = "";
    private const string MicrosoftIpAddress = "";
    private const string Private24Bit = "";
    private const string Private20Bit = "";
    private const string Private16Bit = "";
    private const string PrivateLinkLocal = "";

    public void Setup()
        _httpRequest = M<HttpRequestBase>();

    public void Teardown()
        _httpRequest = null;

    public void PublicIpAndNullXForwardedFor_Returns_CorrectIp()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(null);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void PublicIpAndEmptyXForwardedFor_Returns_CorrectIp()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(string.Empty);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MalformedUserHostAddress_Returns_DefaultIpAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(MalformedIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(null);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MalformedXForwardedFor_Returns_DefaultIpAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(MalformedIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void SingleValidPublicXForwardedFor_Returns_XForwardedFor()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(MicrosoftIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultipleValidPublicXForwardedFor_Returns_LastXForwardedFor()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(GoogleIpAddress + "," + MicrosoftIpAddress);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void SinglePrivateXForwardedFor_Returns_UserHostAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(Private24Bit);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultiplePrivateXForwardedFor_Returns_UserHostAddress()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        const string privateIpList = Private24Bit + "," + Private20Bit + "," + Private16Bit + "," + PrivateLinkLocal;
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(privateIpList);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

    public void MultiplePublicXForwardedForWithPrivateLast_Returns_LastPublic()
        // Arrange
        _httpRequest.Stub(x => x.UserHostAddress).Return(GoogleIpAddress);
        const string privateIpList = Private24Bit + "," + Private20Bit + "," + MicrosoftIpAddress + "," + PrivateLinkLocal;
        _httpRequest.Stub(x => x.ServerVariables[XForwardedFor]).Return(privateIpList);

        // Act
        var ip = RequestHelpers.GetClientIpAddress(_httpRequest);

        // Assert

Error "File google-services.json is missing from module root folder. The Google Services Plugin cannot function without it"

That Problem is because:- The folder or file you pasted to your product downloaded from the firebase console is not named as google-services.json. so now click it then right mouse click in all the options open refractor and rename it to google-services.json. because this worked for me

Adjust UILabel height depending on the text

My approach to compute the dynamic height of UILabel.

    let width = ... //< width of this label 
    let text = ... //< display content

    label.numberOfLines = 0
    label.lineBreakMode = .byWordWrapping
    label.preferredMaxLayoutWidth = width

    // Font of this label.
    //label.font = UIFont.systemFont(ofSize: 17.0)
    // Compute intrinsicContentSize based on font, and preferredMaxLayoutWidth
    // Destination height
    let height = label.intrinsicContentSize.height

Wrap to function:

func computeHeight(text: String, width: CGFloat) -> CGFloat {
    // A dummy label in order to compute dynamic height.
    let label = UILabel()

    label.numberOfLines = 0
    label.lineBreakMode = .byWordWrapping
    label.font = UIFont.systemFont(ofSize: 17.0)

    label.preferredMaxLayoutWidth = width
    label.text = text

    let height = label.intrinsicContentSize.height
    return height

What is the backslash character (\\)?

The \ on it's own is used to escape special characters, such as \n (new line), \t (tabulation), \" (quotes) when typing these specific values in a System.out.println() statement.

Thus, if you want to print a backslash, \, you can't have it on it's own since the compiler will be expecting a special character (such as the ones above). Thus, to print a backslash you need to escape it, since itself is also one of these special characters, thus, \\ yields \.

Can an html element have multiple ids?

You can only have one ID per element, but you can indeed have more than one class. But don't have multiple class attributes, put multiple class values into one attribute.

<div id="foo" class="bar baz bax">

is perfectly legal.

Get encoding of a file in Windows

The only way that I have found to do this is VIM or Notepad++.

How to add `style=display:"block"` to an element using jQuery?


Edit: or as dave thieben points out in his comment below, you can do this as well:

$("#YourElementID").css({ display: "block" });

Read remote file with node.js (http.get)

You can do something like this, without using any external libraries.

const fs = require("fs");
const https = require("https");

const file = fs.createWriteStream("data.txt");

https.get("", response => {
  var stream = response.pipe(file);

  stream.on("finish", function() {

Looping through the content of a file in Bash

Here is my real life example how to loop lines of another program output, check for substrings, drop double quotes from variable, use that variable outside of the loop. I guess quite many is asking these questions sooner or later.

##Parse FPS from first video stream, drop quotes from fps variable
while read -r line; do
  if [[ $FPS == "unknown" ]] && [[ $line == *".codec_type=\"video\""* ]]; then
    echo ParseFPS $line
  if [[ $FPS == "parse" ]] && [[ $line == *".r_frame_rate="* ]]; then
    echo ParseFPS $line
done <<< "$(ffprobe -v quiet -print_format flat -show_format -show_streams -i "$input")"
if [ "$FPS" == "unknown" ] || [ "$FPS" == "parse" ]; then 
  echo ParseFPS Unknown frame rate
echo Found $FPS

Declare variable outside of the loop, set value and use it outside of loop requires done <<< "$(...)" syntax. Application need to be run within a context of current console. Quotes around the command keeps newlines of output stream.

Loop match for substrings then reads name=value pair, splits right-side part of last = character, drops first quote, drops last quote, we have a clean value to be used elsewhere.

How to get all Windows service names starting with a common word?

Save it as a .ps1 file and then execute

powershell -file "path\to your\start stop nation service command file.ps1"

What are the ways to sum matrix elements in MATLAB?

Another answer for the first question is to use one for loop and perform linear indexing into the array using the function NUMEL to get the total number of elements:

total = 0;
for i = 1:numel(A)
  total = total+A(i);

Python: SyntaxError: keyword can't be an expression

I guess many of us who came to this page have a problem with Scikit Learn, one way to solve it is to create a dictionary with parameters and pass it to the model:

params = {'C': 1e9, 'gamma': 1e-07}
cls = SVC(**params)    

Why does Python code use len() function instead of a length method?

Strings do have a length method: __len__()

The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in iter() function (or have the method called behind the scenes for you) on objects which are iterable.

See Emulating container types for more information.

Here's a good read on the subject of protocols in Python: Python and the Principle of Least Astonishment

Easiest way to toggle 2 classes in jQuery

Toggle between two classes 'A' and 'B' with Jquery.

$('#selecor_id').toggleClass("A B");

How do I enable EF migrations for multiple contexts to separate databases?

I just bumped into the same problem and I used the following solution (all from Package Manager Console)

PM> Enable-Migrations -MigrationsDirectory "Migrations\ContextA" -ContextTypeName MyProject.Models.ContextA
PM> Enable-Migrations -MigrationsDirectory "Migrations\ContextB" -ContextTypeName MyProject.Models.ContextB

This will create 2 separate folders in the Migrations folder. Each will contain the generated Configuration.cs file. Unfortunately you still have to rename those Configuration.cs files otherwise there will be complaints about having two of them. I renamed my files to ConfigA.cs and ConfigB.cs

EDIT: (courtesy Kevin McPheat) Remember when renaming the Configuration.cs files, also rename the class names and constructors /EDIT

With this structure you can simply do

PM> Add-Migration -ConfigurationTypeName ConfigA
PM> Add-Migration -ConfigurationTypeName ConfigB

Which will create the code files for the migration inside the folder next to the config files (this is nice to keep those files together)

PM> Update-Database -ConfigurationTypeName ConfigA
PM> Update-Database -ConfigurationTypeName ConfigB

And last but not least those two commands will apply the correct migrations to their corrseponding databases.

EDIT 08 Feb, 2016: I have done a little testing with EF7 version 7.0.0-rc1-16348

I could not get the -o|--outputDir option to work. It kept on giving Microsoft.Dnx.Runtime.Common.Commandline.CommandParsingException: Unrecognized command or argument

However it looks like the first time an migration is added it is added into the Migrations folder, and a subsequent migration for another context is automatically put into a subdolder of migrations.

The original names ContextA seems to violate some naming conventions so I now use ContextAContext and ContextBContext. Using these names you could use the following commands: (note that my dnx still works from the package manager console and I do not like to open a separate CMD window to do migrations)

PM> dnx ef migrations add Initial -c "ContextAContext"
PM> dnx ef migrations add Initial -c "ContextBContext"

This will create a model snapshot and a initial migration in the Migrations folder for ContextAContext. It will create a folder named ContextB containing these files for ContextBContext

I manually added a ContextA folder and moved the migration files from ContextAContext into that folder. Then I renamed the namespace inside those files (snapshot file, initial migration and note that there is a third file under the initial migration file ... designer.cs). I had to add .ContextA to the namespace, and from there the framework handles it automatically again.

Using the following commands would create a new migration for each context

PM>  dnx ef migrations add Update1 -c "ContextAContext"
PM>  dnx ef migrations add Update1 -c "ContextBContext"

and the generated files are put in the correct folders.

Combining Two Images with OpenCV

The three best way to do it using a single line of code

import cv2
import numpy as np 

img = cv2.imread('Imgs/Saint_Roch_new/data/Point_4_Face.jpg')
dim = (256, 256)
resizedLena = cv2.resize(img, dim, interpolation = cv2.INTER_LINEAR)
X, Y = resizedLena, resizedLena

# Methode 1: Using Numpy (hstack, vstack)
Fusion_Horizontal = np.hstack((resizedLena, Y, X))
Fusion_Vertical   = np.vstack((newIMG, X))

cv2.imshow('Fusion_Vertical using vstack', Fusion_Vertical)

# Methode 2: Using Numpy (contanate)
Fusion_Vertical   = np.concatenate((resizedLena, X, Y), axis=0)
Fusion_Horizontal = np.concatenate((resizedLena, X, Y), axis=1)

cv2.imshow("Fusion_Horizontal usung concatenate", Fusion_Horizontal)

# Methode 3: Using OpenCV (vconcat, hconcat)
Fusion_Vertical   = cv2.vconcat([resizedLena, X, Y])
Fusion_Horizontal = cv2.hconcat([resizedLena, X, Y])

cv2.imshow("Fusion_Horizontal Using hconcat", Fusion_Horizontal)

I can't understand why this JAXB IllegalAnnotationException is thrown

In my case, I was able to find the problem by temporarily catching the exception, descending into causes as needed (based on how deep the IllegalAnnotationException was), and calling getErrors() on it.

    try {
        // in my case, this was what gave me an exception
    // I got a WebServiceException caused by another exception, which was caused by the IllegalAnnotationsException
    } catch (WebServiceException e) {
        // Incidentally, I need to call getCause().getCause() on it, and cast to IllegalAnnotationsException before calling getErrors()

std::string formatting like sprintf

C++20 will include std::format which resembles sprintf in terms of API but is fully type-safe, works with user-defined types, and uses Python-like format string syntax. Here's how you will be able to format std::string and write it to a stream:

std::string s = "foo";
std::cout << std::format("Look, a string: {}", s);

Alternatively, you could use the {fmt} library to format a string and write it to stdout or a file stream in one go:

fmt::print("Look, a string: {}", s);

As for sprintf or most of the other answers here, unfortunately they use varargs and are inherently unsafe unless you use something like GCC's format attribute which only works with literal format strings. You can see why these functions are unsafe on the following example:

std::string format_str = "%s";
string_format(format_str, format_str[0]);

where string_format is an implementation from the Erik Aronesty's answer. This code compiles, but it will most likely crash when you try to run it:

$ g++ -Wall -Wextra -pedantic 
$ ./a.out 
Segmentation fault: 11

Disclaimer: I'm the author of {fmt} and C++20 std::format.

How can I make the cursor turn to the wait cursor?

It is easier to use UseWaitCursor at the Form or Window level. A typical use case can look like below:

    private void button1_Click(object sender, EventArgs e)

            this.Enabled = false;//optional, better target a panel or specific controls
            this.UseWaitCursor = true;//from the Form/Window instance
            Application.DoEvents();//messages pumped to update controls
            //execute a lengthy blocking operation here, 
            //bla bla ....
            this.Enabled = true;//optional
            this.UseWaitCursor = false;

For a better UI experience you should use Asynchrony from a different thread.

Is there a keyboard shortcut (hotkey) to open Terminal in macOS?

I tested the following procedure under macOS Mojave 10.14.6 (18G3020).

Launch Automator. Create a document of type “Quick Action”:

quick action template

(In older versions of macOS, use the “Service” template.)

In the new Automator document, add a “Run AppleScript” action. (You can type “run applescript” into the search field at the top of the action list to find it.) Here's the AppleScript to paste into the action:

on run {input, parameters}
    tell application "Terminal"
        if it is running then
            do script ""
        end if
    end tell
end run

Set the “Workflow receives” popup to “no input”. It should look like this overall:

workflow with applescript

Save the document with the name “New Terminal”. Then go to the Automator menu (or the app menu in any running application) and open the Services submenu. You should now see the “New Terminal” quick action:

New Terminal service menu item

If you click the “New Terminal” menu item, you'll get a dialog box:

permission dialog

Click OK to allow the action to run. You'll see this dialog once in each application that's frontmost when you use the action. In other words, the first time you use the action while Finder is frontmost, you'll see the dialog. And the first time you use the action while Safari is frontmost, you'll see the dialog. And so on.

After you click OK in the dialog, Terminal should open a new window.

To assign a keyboard shortcut to the quick action, choose the “Services Preferences…” item from the Services menu. (Or launch System Preferences, choose the Keyboard pane, then choose the Shortcuts tab, then choose Services from the left-hand list.) Scroll to the bottom of the right-hand list and find the New Terminal service. Click it and you should see an “Add Shortcut” button:

add shortcut button

Click the button and press your preferred keyboard shortcut. Then, scratch your head, because (when I tried it) the Add Shortcut button reappears. But click the button again and you should see your shortcut:

keyboard shortcut set

Now you should be able to press your keyboard shortcut in most circumstances to get a new terminal window.

Select the first row by group

I favor the dplyr approach.

group_by(id) followed by either

  • filter(row_number()==1) or
  • slice(1) or
  • slice_head(1) #(dplyr => 1.0)
  • top_n(n = -1)
    • top_n() internally uses the rank function. Negative selects from the bottom of rank.

In some instances arranging the ids after the group_by can be necessary.


# using filter(), top_n() or slice()

m1 <-
test %>% 
  group_by(id) %>% 

m2 <-
test %>% 
  group_by(id) %>% 

m3 <-
test %>% 
  group_by(id) %>% 
  top_n(n = -1)

All three methods return the same result

# A tibble: 5 x 2
# Groups:   id [5]
     id string
  <int> <fct> 
1     1 A     
2     2 B     
3     3 C     
4     4 D     
5     5 E

How to apply multiple transforms in CSS?

Some time in the future, we can write it like this:

li:nth-child(2) {
    rotate: 15deg;
    translate:-20px 0px;        

This will become especially useful when applying individual classes on an element:

<div class="teaser important"></div>

.important{scale:1.5 1.5;}

This syntax is defined in the in-progress CSS Transforms Level 2 specification, but can't find anything about current browser support other then chrome canary. Hope some day i'll come back and update browser support here ;)

Found the info in this article which you might want to check out regarding workarounds for current browsers.

css to make bootstrap navbar transparent

<nav class="navbar navbar-expand-lg navbar-light fixed-top bg-transparent">
              <a class="navbar-brand" href="#">Navbar w/ text</a>
              <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarText" aria-controls="navbarText" aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-toggler-icon"></span>
              <div class="collapse navbar-collapse" id="navbarText">
                <ul class="navbar-nav mr-auto">
                  <li class="nav-item active">
                    <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
                  <li class="nav-item">
                    <a class="nav-link" href="#">Features</a>
                  <li class="nav-item">
                    <a class="nav-link" href="#">Pricing</a>
                <span class="navbar-text">
                  Navbar text with an inline element

What does random.sample() method in python do?

random.sample() also works on text


> text = open("textfile.txt").read() 

> random.sample(text, 5)

> ['f', 's', 'y', 'v', '\n']

\n is also seen as a character so that can also be returned

you could use random.sample() to return random words from a text file if you first use the split method


> words = text.split()

> random.sample(words, 5)

> ['the', 'and', 'a', 'her', 'of']

sh: 0: getcwd() failed: No such file or directory on cited drive

Even i was having the same problem with python virtualenv It got corrected by a simple restart

sudo shutdown -r now

I want to multiply two columns in a pandas DataFrame and add the result into a new column

For me, this is the clearest and most intuitive:

values = []
for action in ['Sell','Buy']:
    amounts = orders_df['Amounts'][orders_df['Action'==action]].values
    if action == 'Sell':
        prices = orders_df['Prices'][orders_df['Action'==action]].values
        prices = -1*orders_df['Prices'][orders_df['Action'==action]].values
    values += list(amounts*prices)  
orders_df['Values'] = values

The .values method returns a numpy array allowing you to easily multiply element-wise and then you can cumulatively generate a list by 'adding' to it.

"rm -rf" equivalent for Windows?

rmdir /S /Q %DIRNAME%

System.Threading.Timer in C# it seems to be not working. It runs very fast every 3 second

I would just do:

private static Timer timer;
 private static void Main()
   timer = new Timer(_ => OnCallBack(), null, 1000 * 10,Timeout.Infinite); //in 10 seconds

  private static void OnCallBack()
    Thread.Sleep(3000); //doing some long operation
    timer = new Timer(_ => OnCallBack(), null, 1000 * 10,Timeout.Infinite); //in 10 seconds

And ignore the period parameter, since you're attempting to control the periodicy yourself.

Your original code is running as fast as possible, since you keep specifying 0 for the dueTime parameter. From Timer.Change:

If dueTime is zero (0), the callback method is invoked immediately.