Programs & Examples On #Ppp

The Point-to-Point protocol enables packet-based communication over a serial interface.

select rows in sql with latest date for each ID repeated multiple times

You can use a join to do this

SELECT t1.* from myTable t1
LEFT OUTER JOIN myTable t2 on t2.ID=t1.ID AND t2.`Date` > t1.`Date`
WHERE t2.`Date` IS NULL;

Only rows which have the latest date for each ID with have a NULL join to t2.

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

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

test rax, 1
jpe even

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

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

Does Enter key trigger a click event?

What personally me fount usable for me is:

(mousedown)="callEvent()" (keyup.enter)="$event.preventDefault()

keyup.enter prevents the event from triggering on keyup, but it still occurs for keydown, that works for me.

Android Studio - Failed to apply plugin [id '']

Open the project on Android Studio and let it solve the problems for you

It immediately shows at the left bottom:

enter image description here

Then click that link, and it will fix the right files for you.

This ended up fixing the Gradle version as mentioned at: but it also fixed further errors, so it is the easiest thing to do.

Tested on , Android Studio 2.3, Ubuntu 14.04.

How to run html file using node js

Just install http-server globally

npm install -g http-server

where ever you need to run a html file run the command http-server For ex: your html file is in /home/project/index.html you can do /home/project/$ http-server

That will give you a link to accessyour webpages: http-server Starting up http-server, serving ./ Available on:

How to use refs in React with Typescript

Just to add a different approach - you can simply cast your ref, something like:

let myInputElement: Element = this.refs["myInput"] as Element

How to solve ERR_CONNECTION_REFUSED when trying to connect to localhost running IISExpress - Error 502 (Cannot debug from Visual Studio)?

Sam's solution worked for me, but I didn't want to run as admin as a permanent solution.

This is how I solved it in my case:

  1. Run CMD as admin
  2. Type "netsh http show urlacl" and find the reserved url with the relevant port
  3. Type "netsh http delete urlacl url=YourReservedUrlHere"

After that I could run my app without the need for admin rights. But it did messed with the ability to browse to my app from an external computer. Close enough for me for now.

Load More Posts Ajax Button in WordPress

UPDATE 24.04.2016.

I've created tutorial on my page about implementing this on Twenty Sixteen theme, so feel free to check it out :)


I've tested this on Twenty Fifteen and it's working, so it should be working for you.

In index.php (assuming that you want to show the posts on the main page, but this should work even if you put it in a page template) I put:

    <div id="ajax-posts" class="row">
            $postsPerPage = 3;
            $args = array(
                    'post_type' => 'post',
                    'posts_per_page' => $postsPerPage,
                    'cat' => 8

            $loop = new WP_Query($args);

            while ($loop->have_posts()) : $loop->the_post();

         <div class="small-12 large-4 columns">
                <h1><?php the_title(); ?></h1>
                <p><?php the_content(); ?></p>

    <div id="more_posts">Load More</div>

This will output 3 posts from category 8 (I had posts in that category, so I used it, you can use whatever you want to). You can even query the category you're in with

$cat_id = get_query_var('cat');

This will give you the category id to use in your query. You could put this in your loader (load more div), and pull with jQuery like

<div id="more_posts" data-category="<?php echo $cat_id; ?>">>Load More</div>

And pull the category with

var cat = $('#more_posts').data('category');

But for now, you can leave this out.

Next in functions.php I added

wp_localize_script( 'twentyfifteen-script', 'ajax_posts', array(
    'ajaxurl' => admin_url( 'admin-ajax.php' ),
    'noposts' => __('No older posts found', 'twentyfifteen'),

Right after the existing wp_localize_script. This will load WordPress own admin-ajax.php so that we can use it when we call it in our ajax call.

At the end of the functions.php file I added the function that will load your posts:

function more_post_ajax(){

    $ppp = (isset($_POST["ppp"])) ? $_POST["ppp"] : 3;
    $page = (isset($_POST['pageNumber'])) ? $_POST['pageNumber'] : 0;

    header("Content-Type: text/html");

    $args = array(
        'suppress_filters' => true,
        'post_type' => 'post',
        'posts_per_page' => $ppp,
        'cat' => 8,
        'paged'    => $page,

    $loop = new WP_Query($args);

    $out = '';

    if ($loop -> have_posts()) :  while ($loop -> have_posts()) : $loop -> the_post();
        $out .= '<div class="small-12 large-4 columns">


add_action('wp_ajax_nopriv_more_post_ajax', 'more_post_ajax');
add_action('wp_ajax_more_post_ajax', 'more_post_ajax');

Here I've added paged key in the array, so that the loop can keep track on what page you are when you load your posts.

If you've added your category in the loader, you'd add:

$cat = (isset($_POST['cat'])) ? $_POST['cat'] : '';

And instead of 8, you'd put $cat. This will be in the $_POST array, and you'll be able to use it in ajax.

Last part is the ajax itself. In functions.js I put inside the $(document).ready(); enviroment

var ppp = 3; // Post per page
var cat = 8;
var pageNumber = 1;

function load_posts(){
    var str = '&cat=' + cat + '&pageNumber=' + pageNumber + '&ppp=' + ppp + '&action=more_post_ajax';
        type: "POST",
        dataType: "html",
        url: ajax_posts.ajaxurl,
        data: str,
        success: function(data){
            var $data = $(data);
            } else{
        error : function(jqXHR, textStatus, errorThrown) {
            $loader.html(jqXHR + " :: " + textStatus + " :: " + errorThrown);

    return false;

$("#more_posts").on("click",function(){ // When btn is pressed.
    $("#more_posts").attr("disabled",true); // Disable the button, temp.

Saved it, tested it, and it works :)

Images as proof (don't mind the shoddy styling, it was done quickly). Also post content is gibberish xD

enter image description here

enter image description here

enter image description here


For 'infinite load' instead on click event on the button (just make it invisible, with visibility: hidden;) you can try with

$(window).on('scroll', function () {
    if ($(window).scrollTop() + $(window).height()  >= $(document).height() - 100) {

This should run the load_posts() function when you're 100px from the bottom of the page. In the case of the tutorial on my site you can add a check to see if the posts are loading (to prevent firing of the ajax twice), and you can fire it when the scroll reaches the top of the footer

$(window).on('scroll', function(){
    if($('body').scrollTop()+$(window).height() > $('footer').offset().top){
        if(!($loader.hasClass('post_loading_loader') || $loader.hasClass('post_no_more_posts'))){

Now the only drawback in these cases is that you could never scroll to the value of $(document).height() - 100 or $('footer').offset().top for some reason. If that should happen, just increase the number where the scroll goes to.

You can easily check it by putting console.logs in your code and see in the inspector what they throw out

$(window).on('scroll', function () {
    console.log($(window).scrollTop() + $(window).height());
    console.log($(document).height() - 100);
    if ($(window).scrollTop() + $(window).height()  >= $(document).height() - 100) {

And just adjust accordingly ;)

Hope this helps :) If you have any questions just ask.

The service cannot accept control messages at this time

Restarting the IIS windows service (World Wide Web Publishing Service) and then starting the application pool has worked for me. However, as the top answer suggests it may have just been the waiting that caused it to subsequently work.

! [rejected] master -> master (fetch first)

Try this git command

git push origin master --force

or short of force -f

git push origin master -f

SQL Network Interfaces, error: 50 - Local Database Runtime error occurred. Cannot create an automatic instance

In my case, we had several projects in one solution and had selected a different start project than in the package manager console when running the "Update-Database" Command with Code-First Migrations. Make sure to select the proper start project.

iOS8 Beta Ad-Hoc App Download (itms-services)

If you have already installed app on your device, try to change bundle identifer on the web .plist (not app plist) with something else like "com.vistair.docunet-test2", after that refresh webpage and try to reinstall... It works for me

Download file from an ASP.NET Web API method using AngularJS

Send your file as a base64 string.

 var element = angular.element('<a/>');
                             href: 'data:attachment/csv;charset=utf-8,' + encodeURI(atob(response.payload)),
                             target: '_blank',
                             download: fname

If attr method not working in Firefox You can also use javaScript setAttribute method

"This operation requires IIS integrated pipeline mode."

The way to fix this issue is not within IIS. I was trying to run my application within IIS Express within Visual Studio. I searched the web and some articles were saying to add an identity tag to the system.web tag. This is not the correct way.

The way I was able to solve this issue was to click on the project file and go to properties. Under managed pipeline, I changed the property value from classic to integrated.

This solved my issue.

Android Studio - Gradle sync project failed

it was hard to solve but i did it look go to C:\Users\Vinnie\ delete .gradle file its you didn't see it it may be in hidden files so if you use windows 7 right click then click on properties and click on hidden to be not checked

then the file will appear then delete it i hope this works Getting the error "Access to the path is denied." while trying to upload files to my Windows Server 2008 R2 Web server

I know this is late to the game, but I wanted to share in case it helps someone.

Your exact situation may not apply, however I had a similar situation and setting the File attribute helped.

Try to set the File attribute to Normal:

var path = Server.MapPath("~/App_Data/file.txt");
File.SetAttributes(path, FileAttributes.Normal);
System.IO.File.WriteAllText(path, "Hello World");

I hope this helps someone.


I found another reason of this error. If you rooted your device access permissions of /data/local/tmp may be changed, so adb can't get access to it temp file. Solution is to create "tmp" folder on sdcard and create symlink to it in /data/local/ (via ADB shell or Root Explorer).

Check if application is installed - Android

If you want to try it without the try catch block, can use the following method, Create a intent and set the package of the app which you want to verify

val intent = Intent(Intent.ACTION_VIEW) = uri

and the call the following method to check if the app is installed

fun isInstalled(intent:Intent) :Boolean{
    val list = context.packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY)
    return list.isNotEmpty()

Fix CSS hover on iPhone/iPad/iPod

Here is a basic, successful use of javascript hover on ios that I made:

Note: I used jQuery, which is hopefully ok for you.


  // Sorry about bad spacing. Also...this is jquery if you didn't notice allready.
    //On Hover - Works on ios
  }, function(){
    //Hover Off - Hover off doesn't seem to work on iOS


.mm { color:#000; padding:15px; }


<div class="mm">hello world</div>
<p>this will disappear on hover of hello world</p>

How to build an android library with Android Studio and gradle?

Here is my solution for mac users I think it work for window also:

First go to your Android Studio toolbar

Build > Make Project (while you guys are online let it to download the files) and then

Build > Compile Module "your app name is shown here" (still online let the files are
download and finish) and then

Run your app that is done it will launch your emulator and configure it then run it!

That is it!!! Happy Coding guys!!!!!!!

Error Message : Cannot find or open the PDB file

I'm also a newbie to CUDA/Visual studio and encountered the same problem with a couple of the samples. If you run DEBUG-> Start Debugging, then repeatedly step over (F10) you'll see the output window appear and get populated. Normal execution returns nomal completion status 0x0 (as you observed) and the output window is closed.

IIS_IUSRS and IUSR permissions in IIS8

When I added IIS_IUSRS permission to site folder - resources, like js and css, still were unaccessible (error 401, forbidden). However, when I added IUSR - it became ok. So for sure "you CANNOT remove the permissions for IUSR without worrying", dear @Travis G@

How to fill a Javascript object literal with many static key/value pairs efficiently?

JavaScript's object literal syntax, which is typically used to instantiate objects (seriously, no one uses new Object or new Array), is as follows:

var obj = {
    'key': 'value',
    'another key': 'another value',
     anUnquotedKey: 'more value!'

For arrays it's:

var arr = [
    'another value',
    'even more values'

If you need objects within objects, that's fine too:

var obj = {
    'subObject': {
        'key': 'value'
    'another object': {
         'some key': 'some value',
         'another key': 'another value',
         'an array': [ 'this', 'is', 'ok', 'as', 'well' ]

This convenient method of being able to instantiate static data is what led to the JSON data format.

JSON is a little more picky, keys must be enclosed in double-quotes, as well as string values:

{"foo":"bar", "keyWithIntegerValue":123}

how to set width for PdfPCell in ItextSharp

try this code I think it is more optimal.

HeaderRow is used to repeat the header of the table for each new page automatically

        BaseFont bfTimes = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, false);
        iTextSharp.text.Font times = new iTextSharp.text.Font(bfTimes, 6, iTextSharp.text.Font.NORMAL, iTextSharp.text.BaseColor.BLACK);

        PdfPTable table = new PdfPTable(10) { HorizontalAlignment = Element.ALIGN_CENTER, WidthPercentage = 100, HeaderRows = 2 };
        table.SetWidths(new float[] { 2f, 6f, 6f, 3f, 5f, 8f, 5f, 5f, 5f, 5f });
        table.AddCell(new PdfPCell(new Phrase("SER.\nNO.", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("TYPE OF SHIPPING", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("ORDER NO.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("QTY.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DISCHARGE PPORT", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DESCRIPTION OF GOODS", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("LINE DOC. RECL DATE", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("CLEARANCE DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("CUSTOM PERMIT NO.", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DISPATCH DATE", times)) { Rowspan = 2, GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("AWB/BL NO.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("COMPLEX NAME", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("G. W. Kgs.", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("DESTINATION", times)) { GrayFill = 0.95f });
        table.AddCell(new PdfPCell(new Phrase("OWNER DOC. RECL DATE", times)) { GrayFill = 0.95f });

adb shell command to make Android package uninstall dialog appear

While the above answers work but in case you have multiple devices connected to your computer then the following command can be used to remove the app from one of them:

adb -s <device-serial> shell pm uninstall <app-package-name>

If you want to find out the device serial then use the following command:

adb devices -l

This will give you a list of devices attached. The left column shows the device serials.

How to fix 'Microsoft Excel cannot open or save any more documents'

Test like this.Sometimes, permission problem.

cmd => dcomcnfg


Component services >Computes >My Computer>Dcom config> and select micro soft Excel Application

Right Click on microsoft Excel Application

Properties>Give Permissions

Select Identity table >Select interactive user >select ok

How to get HttpClient to pass credentials along with the request?

You can configure HttpClient to automatically pass credentials like this:

var myClient = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true });

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

For similar assembly binding errors , following steps may help:

  1. Right click on your Solution and click Manage Nuget Packages for Solution ...
  2. go to Consolidate Tab (last tab) and check if any any differences between packages installed in different projects inside your solution. specially pay attention to your referenced projects which may have lower versions because they usually are less noticed)
  3. consolidate specially packages related to your assembly error and note that many packages are dependent on some other packages like *.code & *.api & ...
  4. after resolving all suspected consolidations , rebuild and rerun the app and see if the assembly bindings are resolved.

Getting the IP address of the current machine using Java

This is a working example of the ACCEPTED answer above! This NetIdentity class will store both the internal host ip, as well as the local loopback. If you're on a DNS based server, as mentioned above, you may need to add some more checks, or possible go the Configuration File Route.

import java.util.Enumeration;

 * Class that allows a device to identify itself on the INTRANET.
 * @author Decoded4620 2016
public class NetIdentity {

    private String loopbackHost = "";
    private String host = "";

    private String loopbackIp = "";
    private String ip = "";
    public NetIdentity(){

            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();

                NetworkInterface i = interfaces.nextElement();
                if(i != null){
                    Enumeration<InetAddress> addresses = i.getInetAddresses();
                        InetAddress address = addresses.nextElement();
                        String hostAddr = address.getHostAddress();

                        // local loopback
                        if(hostAddr.indexOf("127.") == 0 ){
                            this.loopbackIp = address.getHostAddress();
                            this.loopbackHost = address.getHostName();

                        // internal ip addresses (behind this router)
                        if( hostAddr.indexOf("192.168") == 0 || 
                                hostAddr.indexOf("10.") == 0 || 
                                hostAddr.indexOf("172.16") == 0 ){
                   = address.getHostName();
                            this.ip = address.getHostAddress();

                        System.out.println("\t\t-" + address.getHostName() + ":" + address.getHostAddress() + " - "+ address.getAddress());
        catch(SocketException e){

            InetAddress loopbackIpAddress = InetAddress.getLocalHost();
            this.loopbackIp = loopbackIpAddress.getHostName();
            System.out.println("LOCALHOST: " + loopbackIp);
        catch(UnknownHostException e){
            System.err.println("ERR: " + e.toString());

    public String getLoopbackHost(){
        return loopbackHost;

    public String getHost(){
        return host;
    public String getIp(){
        return ip;
    public String getLoopbackIp(){
        return loopbackIp;

When I run this code I actually get a print out like this:

    Software Loopback Interface 1
        - - [B@19e1023e
        -0:0:0:0:0:0:0:1:0:0:0:0:0:0:0:1 - [B@7cef4e59
Broadcom 802.11ac Network Adapter - [B@64b8f8f4
        -fe80:0:0:0:81fa:31d:21c9:85cd%wlan0:fe80:0:0:0:81fa:31d:21c9:85cd%wlan0 - [B@2db0f6b2
Microsoft Kernel Debug Network Adapter
Intel Edison USB RNDIS Device
Driver for user-mode network applications
Cisco Systems VPN Adapter for 64-bit Windows
VirtualBox Host-Only Ethernet Adapter
        -VIKING: - [B@3cd1f1c8
        -VIKING:fe80:0:0:0:d599:3cf0:5462:cb7%eth4 - [B@3a4afd8d
LogMeIn Hamachi Virtual Ethernet Adapter
        -VIKING: - [B@1996cd68
        -VIKING:2620:9b:0:0:0:0:1971:7627 - [B@3339ad8e
        -VIKING:fe80:0:0:0:51bf:994d:4656:8486%eth5 - [B@555590
Bluetooth Device (Personal Area Network)
        -fe80:0:0:0:4c56:8009:2bca:e16b%eth6:fe80:0:0:0:4c56:8009:2bca:e16b%eth6 - [B@3c679bde
Bluetooth Device (RFCOMM Protocol TDI)
Intel(R) Ethernet Connection (2) I218-V
        -fe80:0:0:0:4093:d169:536c:7c7c%eth7:fe80:0:0:0:4093:d169:536c:7c7c%eth7 - [B@16b4a017
Microsoft Wi-Fi Direct Virtual Adapter
        -fe80:0:0:0:103e:cdf0:c0ac:1751%wlan1:fe80:0:0:0:103e:cdf0:c0ac:1751%wlan1 - [B@8807e25
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0000
VirtualBox Host-Only Ethernet Adapter-WFP Native MAC Layer LightWeight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0001
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0002
VirtualBox Host-Only Ethernet Adapter-VirtualBox NDIS Light-Weight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0003
VirtualBox Host-Only Ethernet Adapter-QoS Packet Scheduler-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0004
VirtualBox Host-Only Ethernet Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0000
Intel(R) Ethernet Connection (2) I218-V-WFP Native MAC Layer LightWeight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0001
Intel(R) Ethernet Connection (2) I218-V-Shrew Soft Lightweight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0002
Intel(R) Ethernet Connection (2) I218-V-VirtualBox NDIS Light-Weight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0003
Intel(R) Ethernet Connection (2) I218-V-QoS Packet Scheduler-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0004
Intel(R) Ethernet Connection (2) I218-V-WFP 802.3 MAC Layer LightWeight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0005
Broadcom 802.11ac Network Adapter-WFP Native MAC Layer LightWeight Filter-0000
Broadcom 802.11ac Network Adapter-Virtual WiFi Filter Driver-0000
Broadcom 802.11ac Network Adapter-Native WiFi Filter Driver-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0003
Broadcom 802.11ac Network Adapter-Shrew Soft Lightweight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0004
Broadcom 802.11ac Network Adapter-VirtualBox NDIS Light-Weight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Broadcom 802.11ac Network Adapter-QoS Packet Scheduler-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0006
Broadcom 802.11ac Network Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0007
Microsoft Wi-Fi Direct Virtual Adapter-WFP Native MAC Layer LightWeight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-Native WiFi Filter Driver-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0002
Microsoft Wi-Fi Direct Virtual Adapter-Shrew Soft Lightweight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0003
Microsoft Wi-Fi Direct Virtual Adapter-VirtualBox NDIS Light-Weight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0004
Microsoft Wi-Fi Direct Virtual Adapter-QoS Packet Scheduler-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Microsoft Wi-Fi Direct Virtual Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0006

For my use I'm setting up a Upnp Server, it helped to understand the 'pattern' that i was looking for. Some of the objects returned are Ethernet Adapters, Network Adapters, Virtual Network Adapters, Drivers, and VPN Client Adapters. Not everything has an Address either. So you'll want to skip out on interface objects that don't.

You can also add this to the loop for the current NetworkInterface i

    Enumeration<InetAddress> addresses = i.getInetAddresses();
    System.out.println("\t- name:" + i.getName());
    System.out.println("\t- idx:" + i.getIndex());
    System.out.println("\t- max trans unit (MTU):" + i.getMTU());
    System.out.println("\t- is loopback:" + i.isLoopback());
    System.out.println("\t- is PPP:" + i.isPointToPoint());
    System.out.println("\t- isUp:" + i.isUp());
    System.out.println("\t- isVirtual:" + i.isVirtual());
    System.out.println("\t- supportsMulticast:" + i.supportsMulticast());

And You'll see information in your output much like this:

Software Loopback Interface 1
    - name:lo
    - idx:1
    - max trans unit (MTU):-1
    - is loopback:true
    - is PPP:false
    - isUp:true
    - isVirtual:false
    - supportsMulticast:true
        -ADRESS: [] - [B@19e1023e
        -ADRESS: [0:0:0:0:0:0:0:1(VIKING-]0:0:0:0:0:0:0:1:0:0:0:0:0:0:0:1 - [B@7cef4e59
Broadcom 802.11ac Network Adapter
    - name:wlan0
    - idx:2
    - max trans unit (MTU):1500
    - is loopback:false
    - is PPP:false
    - isUp:true
    - isVirtual:false
    - supportsMulticast:true
        -ADRESS: [] - [B@64b8f8f4
        -ADRESS: [fe80:0:0:0:81fa:31d:21c9:85cd%wlan0(VIKING-]fe80:0:0:0:81fa:31d:21c9:85cd%wlan0:fe80:0:0:0:81fa:31d:21c9:85cd%wlan0 - [B@2db0f6b2
Microsoft Kernel Debug Network Adapter
    - name:eth0
    - idx:3
    - max trans unit (MTU):-1
    - is loopback:false
    - is PPP:false
    - isUp:false
    - isVirtual:false
    - supportsMulticast:true

Android: No Activity found to handle Intent error? How it will resolve

in my case, i was sure that the action is correct, but i was passing wrong URL, i passed the website link without the http:// in it's beginning, so it caused the same issue, here is my manifest (part of it)

        android:label="MyBrowser Activity" >
            <action android:name="android.intent.action.VIEW" />
            <action android:name="com.dsociety.activities.MyBrowser" />

            <category android:name="android.intent.category.DEFAULT" />

            <data android:scheme="http" />

when i code the following, the same Exception is thrown at run time :

Intent intent = new Intent();
intent.setData(Uri.parse(""));    // should be

How to query a MS-Access Table from MS-Excel (2010) using VBA

The Provider piece must be Provider=Microsoft.ACE.OLEDB.12.0 if your target database is ACCDB format. Provider=Microsoft.Jet.OLEDB.4.0 only works for the older MDB format.

You shouldn't even need Access installed if you're running 32 bit Windows. Jet 4 is included as part of the operating system. If you're using 64 bit Windows, Jet 4 is not included, but you still wouldn't need Access itself installed. You can install the Microsoft Access Database Engine 2010 Redistributable. Make sure to download the matching version (AccessDatabaseEngine.exe for 32 bit Windows, or AccessDatabaseEngine_x64.exe for 64 bit).

You can avoid the issue about which ADO version reference by using late binding, which doesn't require any reference.

Dim conn As Object
Set conn = CreateObject("ADODB.Connection")

Then assign your ConnectionString property to the conn object. Here is a quick example which runs from a code module in Excel 2003 and displays a message box with the row count for MyTable. It uses late binding for the ADO connection and recordset objects, so doesn't require setting a reference.

Public Sub foo()
    Dim cn As Object
    Dim rs As Object
    Dim strSql As String
    Dim strConnection As String
    Set cn = CreateObject("ADODB.Connection")
    strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
        "Data Source=C:\Access\webforums\whiteboard2003.mdb"
    strSql = "SELECT Count(*) FROM MyTable;"
    cn.Open strConnection
    Set rs = cn.Execute(strSql)
    MsgBox rs.fields(0) & " rows in MyTable"
    Set rs = Nothing
    Set cn = Nothing
End Sub

If this answer doesn't resolve the problem, edit your question to show us the full connection string you're trying to use and the exact error message you get in response for that connection string.

Login failed for user 'IIS APPPOOL\ASP.NET v4.0'

If you have your connection string added in your web.config, make sure that "Integrated Security=false;" so it would use the id and password specified in the web.config.

    <add providerName="System.Data.SqlClient" name="MyDbContext" connectionString="Data Source=localhost,1433;Initial Catalog=MyDatabase;user id=MyUserName;Password=MyPassword;Trusted_Connection=true;Integrated Security=false;" />

IIS7 Permissions Overview - ApplicationPoolIdentity

Part A: Configuring your Application Pool

Suppose the Application Pool is named 'MyPool' Go to 'Advanced Settings' of the Application Pool from the IIS Manager

  1. Scroll down to 'Identity'. Trying to edit the value will bring up a dialog box. Select 'Built-In account' and under it, select 'ApplicationPoolIdentity'.

  2. A few lines below 'Identity', you should find 'Load User Profile'. This value should be set to 'True'.

Part B: Configuring your website

  1. Website Name: SiteName (just an example)
  2. Physical Path: C:\Whatever (just an example)
  3. Connect as... : Application User (pass-through authentication) (The above settings can be found in 'Basic Settings' of the site in the IIS Manager)
  4. After configuring the basic settings, look for the 'Authentication' configuration under 'IIS' in the main console of the site. Open it. You should see an option for 'Anonymous Authentication'. Make sure it is enabled. Then right click and 'Edit...' it. Select 'Application Pool Identity'.

Part C: Configuring your folder

The folder in question is C:\Whatever

  1. Go to Properties - Sharing - Advanced Sharing - Permissions, and tick 'Share this folder'
  2. In the same dialog box, you will find a button 'Permissions'. Click it.
  3. A new dialog box will open. Click 'Add'.
  4. A new dialog box 'Select Users or Groups' will open. Under 'From this location' make sure the name is the same as your local host computer. Then, under 'Enter the object names', type 'IIS AppPool\MyPool' and click 'Check Names' and then 'Ok'
  5. Give full sharing permissions for 'MyPool' user. Apply it and close the folder properties
  6. Open folder properties again. This time, go to Security - Advanced - Permission, and click Add. There will be an option 'Select a Principal' at the top, or some other option to choose a user. Click it.
  7. The 'Select Users or Groups' dialog box will open again. Repeat step 4.
  8. Give all or as many permissions you need to the 'MyPool' user.
  9. Check 'Replace all child object permissions..." and Apply and close.

You should now be able to use the browse the website

Strip Leading and Trailing Spaces From Java String

Use String#trim() method or String allRemoved = myString.replaceAll("^\\s+|\\s+$", "") for trim both the end.

For left trim:

String leftRemoved = myString.replaceAll("^\\s+", "");

For right trim:

String rightRemoved = myString.replaceAll("\\s+$", "");

Parse json string using JSON.NET

I did not test the following snippet... hopefully it will point you towards the right direction:

    var jsreader = new JsonTextReader(new StringReader(stringData));
    var json = (JObject)new JsonSerializer().Deserialize(jsreader);
    var tableRows = from p in json["items"]
                 select new
                     Name = (string)p["Name"],
                     Age = (int)p["Age"],
                     Job = (string)p["Job"]

What are all the user accounts for IIS/ASP.NET and how do they differ?

This is a very good question and sadly many developers don't ask enough questions about IIS/ASP.NET security in the context of being a web developer and setting up IIS. So here goes....

To cover the identities listed:


This is analogous to the old IIS6 IIS_WPG group. It's a built-in group with it's security configured such that any member of this group can act as an application pool identity.


This account is analogous to the old IUSR_<MACHINE_NAME> local account that was the default anonymous user for IIS5 and IIS6 websites (i.e. the one configured via the Directory Security tab of a site's properties).

For more information about IIS_IUSRS and IUSR see:

Understanding Built-In User and Group Accounts in IIS 7


If an application pool is configured to run using the Application Pool Identity feature then a "synthesised" account called IIS AppPool\<pool name> will be created on the fly to used as the pool identity. In this case there will be a synthesised account called IIS AppPool\DefaultAppPool created for the life time of the pool. If you delete the pool then this account will no longer exist. When applying permissions to files and folders these must be added using IIS AppPool\<pool name>. You also won't see these pool accounts in your computers User Manager. See the following for more information:

Application Pool Identities

ASP.NET v4.0: -

This will be the Application Pool Identity for the ASP.NET v4.0 Application Pool. See DefaultAppPool above.


The NETWORK SERVICE account is a built-in identity introduced on Windows 2003. NETWORK SERVICE is a low privileged account under which you can run your application pools and websites. A website running in a Windows 2003 pool can still impersonate the site's anonymous account (IUSR_ or whatever you configured as the anonymous identity).

In ASP.NET prior to Windows 2008 you could have ASP.NET execute requests under the Application Pool account (usually NETWORK SERVICE). Alternatively you could configure ASP.NET to impersonate the site's anonymous account via the <identity impersonate="true" /> setting in web.config file locally (if that setting is locked then it would need to be done by an admin in the machine.config file).

Setting <identity impersonate="true"> is common in shared hosting environments where shared application pools are used (in conjunction with partial trust settings to prevent unwinding of the impersonated account).

In IIS7.x/ASP.NET impersonation control is now configured via the Authentication configuration feature of a site. So you can configure to run as the pool identity, IUSR or a specific custom anonymous account.


The LOCAL SERVICE account is a built-in account used by the service control manager. It has a minimum set of privileges on the local computer. It has a fairly limited scope of use:

LocalService Account


You didn't ask about this one but I'm adding for completeness. This is a local built-in account. It has fairly extensive privileges and trust. You should never configure a website or application pool to run under this identity.

LocalSystem Account

In Practice:

In practice the preferred approach to securing a website (if the site gets its own application pool - which is the default for a new site in IIS7's MMC) is to run under Application Pool Identity. This means setting the site's Identity in its Application Pool's Advanced Settings to Application Pool Identity:

enter image description here

In the website you should then configure the Authentication feature:

enter image description here

Right click and edit the Anonymous Authentication entry:

enter image description here

Ensure that "Application pool identity" is selected:

enter image description here

When you come to apply file and folder permissions you grant the Application Pool identity whatever rights are required. For example if you are granting the application pool identity for the ASP.NET v4.0 pool permissions then you can either do this via Explorer:

enter image description here

Click the "Check Names" button:

enter image description here

Or you can do this using the ICACLS.EXE utility:

icacls c:\wwwroot\mysite /grant "IIS AppPool\ASP.NET v4.0":(CI)(OI)(M)

...or...if you site's application pool is called BobsCatPicBlogthen:

icacls c:\wwwroot\mysite /grant "IIS AppPool\BobsCatPicBlog":(CI)(OI)(M)

I hope this helps clear things up.


I just bumped into this excellent answer from 2009 which contains a bunch of useful information, well worth a read:

The difference between the 'Local System' account and the 'Network Service' account?

IIS AppPoolIdentity and file system write access permissions

I tried this to fix access issues to an IIS website, which manifested as something like the following in the Event Logs ? Windows ? Application:

Log Name:      Application
Source:        ASP.NET 4.0.30319.0
Date:          1/5/2012 4:12:33 PM
Event ID:      1314
Task Category: Web Event
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      SALTIIS01

Event code: 4008 
Event message: File authorization failed for the request. 
Event time: 1/5/2012 4:12:33 PM 
Event time (UTC): 1/6/2012 12:12:33 AM 
Event ID: 349fcb2ec3c24b16a862f6eb9b23dd6c 
Event sequence: 7 
Event occurrence: 3 
Event detail code: 0 

Application information: 
    Application domain: /LM/W3SVC/2/ROOT/Application/SNCDW-19-129702818025409890 
    Trust level: Full 
    Application Virtual Path: /Application/SNCDW 
    Application Path: D:\Sites\WCF\Application\SNCDW\ 
    Machine name: SALTIIS01 

Process information: 
    Process ID: 1896 
    Process name: w3wp.exe 
    Account name: iisservice 

Request information: 
    Request URL: http://webservicestest/Application/SNCDW/PC.svc 
    Request path: /Application/SNCDW/PC.svc 
    User host address: 
    User: js3228 
    Is authenticated: True 
    Authentication Type: Negotiate 
    Thread account name: iisservice 

In the end I had to give the Windows Everyone group read access to that folder to get it to work properly.

Receiving login prompt using integrated windows authentication

Add permission [Domain Users] to your web security.

  • Right click on your site in IIS under the Sites folder
  • Click Edit Permissions...
  • Select the Security tab
  • Under the Group or usernames section click the Edit... button
  • In the Permissions pop up, under the Group or user names click Add...
  • Enter [Domain Users] in the object names to select text area and click OK to apply the change
  • Click OK to close the Permissions pop up
  • Click OK to close the Properties pop up and apply your new settings

How to add ASP.NET 4.0 as Application Pool on IIS 7, Windows 7

Installing framework 4.0 redistributable is also enough to create application pool. You can download it from here.

Unable to start debugging on the web server. Could not start ASP.NET debugging VS 2010, II7, Win 7 x64


In addition to Aaron's suggestions, try the following

  • Check that integrated windows authentication is selected in your IIS website
  • Can you debug using Cassini instead of IIS?

Reading a registry key in C#

You're looking for the cunningly named Registry.GetValue method.

Python base64 data decode

After decoding, it looks like the data is a repeating structure that's 8 bytes long, or some multiple thereof. It's just binary data though; what it might mean, I have no idea. There are 2064 entries, which means that it could be a list of 2064 8-byte items down to 129 128-byte items.

How to give ASP.NET access to a private key in a certificate in the certificate store?

For me, it was nothing more than re-importing the certificate with "Allow private key to be exported" checked.

I guess it is necessary, but it does make me nervous as it is a third party app accessing this certificate.

PHP json_decode() returns NULL with valid JSON?

I had the same problem and I solved it simply by replacing the quote character before decode.

$json = str_replace('&quot;', '"', $json);
$object = json_decode($json);

My JSON value was generated by JSON.stringify function.

Cannot use a leading ../ to exit above the top directory

I had the problem occur on my system in a very strange way. In my system customers create products that sit inside a directory structure of product categories. So ProductA might sit in the folder CategoryInner inside the folder CategoryOuter. I had just added a feature where my URL would show the category nesting on the URL thusly:

Obviously the nesting on the URL was just for SEO purposes (and to show the user what category their product was sitting in. But when I used ResolveClientUrl on some URLs that used to work, it must've been confused by the extra fake pathing. The error message was popping up in the debugger on some line that was never the problem so it took me quite some time to figure out what was going on. I wnet through and removed all of my ResolveClientUrl calls that acted on anything that didn't start with a ~ and made the rest of the paths absolute paths.

Solving SharePoint Server 2010 - 503. The service is unavailable, After installation

I had the same issue but the password was good and "Log on as batch job" alone was not sufficient.

Check that the IIS application pool identity account or group has both the "Log on as Batch Job" permission AND that it can "impersonate a client after authentication".

To change these settings perform the following steps on the web front end server:

  • Start>Run type "secpol.msc"
    • Find: Security Settings>Local Policies>User Rights assignment
    • Add user or group to "Log on as Batch Job"
    • Check group membership of service account (in Active Directory) if a particular group is being used for this purpose.
    • Find "impersonate a client after authentication" and add the application pool identity
    • Reboot the server

You should be able to access the site!

Add IIS 7 AppPool Identities as SQL Server Logons

This may be what you are looking for...

I would also advise longer term to consider a limited rights domain user, what you are trying works fine in a silo machine scenario but you are going to have to make changes if you move to another machine for the DB server.

How to change the data type of a column without dropping the column with query?

MSDN says

ALTER TABLE mytable ALTER COLUMN mycolumn newtype

Beware of the limitations of the ALTER COLUMN clause listed in the article

What Are Some Good .NET Profilers?

We selected YourKit Profiler for .NET in my company as it was the best value (price vs. feature). For a small company that wants to have flexible licensing (floating licenses) it was a perfect choice - ANTS was developer seat locket at the time.

Also, it provided us with the ability to attach to the running process which was not possible with dotTrace. Beware though that attaching is not the best option as everything .NET will slow down, but this was the only way to profile .NET applications started by other processes. Feature wise, ANTS and dotTrace were better - but in the end YourKit was good enough.

jquery clear input default value

Unless you're really worried about older browsers, you could just use the new html5 placeholder attribute like so:

<input type="text" name="email" placeholder="Email address" class="input" />

Python str vs unicode types

Unicode and encodings are completely different, unrelated things.


Assigns a numeric ID to each character:

  • 0x41 ? A
  • 0xE1 ? á
  • 0x414 ? ?

So, Unicode assigns the number 0x41 to A, 0xE1 to á, and 0x414 to ?.

Even the little arrow ? I used has its Unicode number, it's 0x2192. And even emojis have their Unicode numbers, is 0x1F602.

You can look up the Unicode numbers of all characters in this table. In particular, you can find the first three characters above here, the arrow here, and the emoji here.

These numbers assigned to all characters by Unicode are called code points.

The purpose of all this is to provide a means to unambiguously refer to a each character. For example, if I'm talking about , instead of saying "you know, this laughing emoji with tears", I can just say, Unicode code point 0x1F602. Easier, right?

Note that Unicode code points are usually formatted with a leading U+, then the hexadecimal numeric value padded to at least 4 digits. So, the above examples would be U+0041, U+00E1, U+0414, U+2192, U+1F602.

Unicode code points range from U+0000 to U+10FFFF. That is 1,114,112 numbers. 2048 of these numbers are used for surrogates, thus, there remain 1,112,064. This means, Unicode can assign a unique ID (code point) to 1,112,064 distinct characters. Not all of these code points are assigned to a character yet, and Unicode is extended continuously (for example, when new emojis are introduced).

The important thing to remember is that all Unicode does is to assign a numerical ID, called code point, to each character for easy and unambiguous reference.


Map characters to bit patterns.

These bit patterns are used to represent the characters in computer memory or on disk.

There are many different encodings that cover different subsets of characters. In the English-speaking world, the most common encodings are the following:


Maps 128 characters (code points U+0000 to U+007F) to bit patterns of length 7.


  • a ? 1100001 (0x61)

You can see all the mappings in this table.

ISO 8859-1 (aka Latin-1)

Maps 191 characters (code points U+0020 to U+007E and U+00A0 to U+00FF) to bit patterns of length 8.


  • a ? 01100001 (0x61)
  • á ? 11100001 (0xE1)

You can see all the mappings in this table.


Maps 1,112,064 characters (all existing Unicode code points) to bit patterns of either length 8, 16, 24, or 32 bits (that is, 1, 2, 3, or 4 bytes).


  • a ? 01100001 (0x61)
  • á ? 11000011 10100001 (0xC3 0xA1)
  • ? ? 11100010 10001001 10100000 (0xE2 0x89 0xA0)
  • ? 11110000 10011111 10011000 10000010 (0xF0 0x9F 0x98 0x82)

The way UTF-8 encodes characters to bit strings is very well described here.

Unicode and Encodings

Looking at the above examples, it becomes clear how Unicode is useful.

For example, if I'm Latin-1 and I want to explain my encoding of á, I don't need to say:

"I encode that a with an aigu (or however you call that rising bar) as 11100001"

But I can just say:

"I encode U+00E1 as 11100001"

And if I'm UTF-8, I can say:

"Me, in turn, I encode U+00E1 as 11000011 10100001"

And it's unambiguously clear to everybody which character we mean.

Now to the often arising confusion

It's true that sometimes the bit pattern of an encoding, if you interpret it as a binary number, is the same as the Unicode code point of this character.

For example:

  • ASCII encodes a as 1100001, which you can interpret as the hexadecimal number 0x61, and the Unicode code point of a is U+0061.
  • Latin-1 encodes á as 11100001, which you can interpret as the hexadecimal number 0xE1, and the Unicode code point of á is U+00E1.

Of course, this has been arranged like this on purpose for convenience. But you should look at it as a pure coincidence. The bit pattern used to represent a character in memory is not tied in any way to the Unicode code point of this character.

Nobody even says that you have to interpret a bit string like 11100001 as a binary number. Just look at it as the sequence of bits that Latin-1 uses to encode the character á.

Back to your question

The encoding used by your Python interpreter is UTF-8.

Here's what's going on in your examples:

Example 1

The following encodes the character á in UTF-8. This results in the bit string 11000011 10100001, which is saved in the variable a.

>>> a = 'á'

When you look at the value of a, its content 11000011 10100001 is formatted as the hex number 0xC3 0xA1 and output as '\xc3\xa1':

>>> a

Example 2

The following saves the Unicode code point of á, which is U+00E1, in the variable ua (we don't know which data format Python uses internally to represent the code point U+00E1 in memory, and it's unimportant to us):

>>> ua = u'á'

When you look at the value of ua, Python tells you that it contains the code point U+00E1:

>>> ua

Example 3

The following encodes Unicode code point U+00E1 (representing character á) with UTF-8, which results in the bit pattern 11000011 10100001. Again, for output this bit pattern is represented as the hex number 0xC3 0xA1:

>>> ua.encode('utf-8')

Example 4

The following encodes Unicode code point U+00E1 (representing character á) with Latin-1, which results in the bit pattern 11100001. For output, this bit pattern is represented as the hex number 0xE1, which by coincidence is the same as the initial code point U+00E1:

>>> ua.encode('latin1')

There's no relation between the Unicode object ua and the Latin-1 encoding. That the code point of á is U+00E1 and the Latin-1 encoding of á is 0xE1 (if you interpret the bit pattern of the encoding as a binary number) is a pure coincidence.

Transport security has blocked a cleartext HTTP

Figuring out what settings to use can be performed automatically, as mentioned in this technote:

/usr/bin/nscurl --ats-diagnostics --verbose

Do I need Content-Type: application/octet-stream for file download?


The content-type should be whatever it is known to be, if you know it. application/octet-stream is defined as "arbitrary binary data" in RFC 2046, and there's a definite overlap here of it being appropriate for entities whose sole intended purpose is to be saved to disk, and from that point on be outside of anything "webby". Or to look at it from another direction; the only thing one can safely do with application/octet-stream is to save it to file and hope someone else knows what it's for.

You can combine the use of Content-Disposition with other content-types, such as image/png or even text/html to indicate you want saving rather than display. It used to be the case that some browsers would ignore it in the case of text/html but I think this was some long time ago at this point (and I'm going to bed soon so I'm not going to start testing a whole bunch of browsers right now; maybe later).

RFC 2616 also mentions the possibility of extension tokens, and these days most browsers recognise inline to mean you do want the entity displayed if possible (that is, if it's a type the browser knows how to display, otherwise it's got no choice in the matter). This is of course the default behaviour anyway, but it means that you can include the filename part of the header, which browsers will use (perhaps with some adjustment so file-extensions match local system norms for the content-type in question, perhaps not) as the suggestion if the user tries to save.


Content-Type: application/octet-stream
Content-Disposition: attachment; filename="picture.png"

Means "I don't know what the hell this is. Please save it as a file, preferably named picture.png".

Content-Type: image/png
Content-Disposition: attachment; filename="picture.png"

Means "This is a PNG image. Please save it as a file, preferably named picture.png".

Content-Type: image/png
Content-Disposition: inline; filename="picture.png"

Means "This is a PNG image. Please display it unless you don't know how to display PNG images. Otherwise, or if the user chooses to save it, we recommend the name picture.png for the file you save it as".

Of those browsers that recognise inline some would always use it, while others would use it if the user had selected "save link as" but not if they'd selected "save" while viewing (or at least IE used to be like that, it may have changed some years ago).

Java: Detect duplicates in ArrayList?

If you are looking to avoid having duplicates at all, then you should just cut out the middle process of detecting duplicates and use a Set.

How to convert a String into an ArrayList?

Ok i'm going to extend on the answers here since a lot of the people who come here want to split the string by a whitespace. This is how it's done:

List<String> List = new ArrayList<String>(Arrays.asList(s.split("\\s+")));

Select dropdown with fixed width cutting off content in IE

I did Google about this issue but didn't find any best solution ,So Created a solution that works fine in all browsers.

just call badFixSelectBoxDataWidthIE() function on page load.

function badFixSelectBoxDataWidthIE(){
    if ($.browser.msie){
    if($(this).attr('multiple')== false){
               if($(this).css("width") != "auto") {
                   var width = $(this).width();
                   $(this).data("origWidth", $(this).css("width"))
                          .css("width", "auto");
                   /* if the width is now less than before then undo */
                   if($(this).width() < width) {
                       $(this).css("width", $(this).data("origWidth"));
           /* Handle blur if the user does not change the value */
               $(this).css("width", $(this).data("origWidth"));

           /* Handle change of the user does change the value */
               $(this).css("width", $(this).data("origWidth"));


Invalid character in identifier

You don't get a good error message in IDLE if you just Run the module. Try typing an import command from within IDLE shell, and you'll get a much more informative error message. I had the same error and that made all the difference.

(And yes, I'd copied the code from an ebook and it was full of invisible "wrong" characters.)

Save and load weights in keras

Here is a YouTube video that explains exactly what you're wanting to do: Save and load a Keras model

There are three different saving methods that Keras makes available. These are described in the video link above (with examples), as well as below.

First, the reason you're receiving the error is because you're calling load_model incorrectly.

To save and load the weights of the model, you would first use


to save the weights, as you've displayed. To load the weights, you would first need to build your model, and then call load_weights on the model, as in


Another saving technique is This save function saves:

  • The architecture of the model, allowing to re-create the model.
  • The weights of the model.
  • The training configuration (loss, optimizer).
  • The state of the optimizer, allowing to resume training exactly where you left off.

To load this saved model, you would use the following:

from keras.models import load_model
new_model = load_model(filepath)'

Lastly, model.to_json(), saves only the architecture of the model. To load the architecture, you would use

from keras.models import model_from_json
model = model_from_json(json_string)

Maven: repository element was not specified in the POM inside distributionManagement?

I got the same message ("repository element was not specified in the POM inside distributionManagement element"). I checked /target/checkout/pom.xml and as per another answer and it really lacked <distributionManagement>.

It turned out that the problem was that <distributionManagement> was missing in pom.xml in my master branch (using git).

After cleaning up (mvn release:rollback, mvn clean, mvn release:clean, git tag -d v1.0.0) I run mvn release again and it worked.

Parse strings to double with comma and point

You can check if the string contains a decimal point using

string s="";

        if (s.Contains(','))
        //treat as double how you wish

and then treat that as a decimal, otherwise just pass the non-double value along.

nginx 502 bad gateway


fastcgi_pass    unix:/var/run/php-fpm.sock;


fastcgi_pass    unix:/var/run/php5-fpm.sock;

How to restart a rails server on Heroku?

heroku ps:restart [web|worker] --app app_name

works for all processes declared in your Procfile. So if you have multiple web processes or worker processes, each labeled with a number, you can selectively restart one of them:

heroku ps:restart web.2 --app app_name
heroku ps:restart worker.3 --app app_name

HTML Input="file" Accept Attribute File Type (CSV)

You can know the correct content-type for any file by just doing the following:

1) Select interested file,

2) And run in console this:


You can also set attribute "multiple" for your input to check content-type for several files at a time and do next:

for (var i = 0; i < $('.file-input')[0].files.length; i++){

Attribute accept has some problems with multiple attribute and doesn't work correctly in this case.

ASP.NET Core Web API exception handling

Use built-in Exception Handling Middleware

Step 1. In your startup, register your exception handling route:

// It should be one of your very first registrations
app.UseExceptionHandler("/error"); // Add this
app.UseEndpoints(endpoints => endpoints.MapControllers());

Step 2. Create controller that will handle all exceptions and produce error response:

[ApiExplorerSettings(IgnoreApi = true)]
public class ErrorsController : ControllerBase
    public MyErrorResponse Error()
        var context = HttpContext.Features.Get<IExceptionHandlerFeature>();
        var exception = context.Error; // Your exception
        var code = 500; // Internal Server Error by default

        if      (exception is MyNotFoundException) code = 404; // Not Found
        else if (exception is MyUnauthException)   code = 401; // Unauthorized
        else if (exception is MyException)         code = 400; // Bad Request

        Response.StatusCode = code; // You can use HttpStatusCode enum instead

        return new MyErrorResponse(exception); // Your error model

A few important notes and observations:

  • [ApiExplorerSettings(IgnoreApi = true)] is needed. Otherwise, it may break your Swashbuckle swagger
  • Again, app.UseExceptionHandler("/error"); has to be one of the very top registrations in your Startup Configure(...) method. It's probably safe to place it at the top of the method.
  • The path in app.UseExceptionHandler("/error") and in controller [Route("error")] should be the same, to allow the controller handle exceptions redirected from exception handler middleware.

Microsoft documentation for this subject is not that great but has some interesting ideas. I'll just leave the link here.

Response models and custom exceptions

Implement your own response model and exceptions. This example is just a good starting point. Every service would need to handle exceptions in its own way. But with this code, you have full flexibility and control over handling exceptions and returning a proper result to the caller.

An example of error response model (just to give you some ideas):

public class MyErrorResponse
    public string Type { get; set; }
    public string Message { get; set; }
    public string StackTrace { get; set; }

    public MyErrorResponse(Exception ex)
        Type = ex.GetType().Name;
        Message = ex.Message;
        StackTrace = ex.ToString();

For simpler services, you might want to implement http status code exception that would look like this:

public class HttpStatusException : Exception
    public HttpStatusCode Status { get; private set; }

    public HttpStatusException(HttpStatusCode status, string msg) : base(msg)
        Status = status;

This can be thrown like that:

throw new HttpStatusCodeException(HttpStatusCode.NotFound, "User not found");

Then your handling code could be simplified to:

if (exception is HttpStatusException httpException)
    code = (int) httpException.Status;

Why so un-obvious HttpContext.Features.Get<IExceptionHandlerFeature>()?

ASP.NET Core developers embraced the concept of middlewares where different aspects of functionality such as Auth, Mvc, Swagger etc. are separated and executed sequentially by processing the request and returning the response or passing the execution to the next middleware. With this architecture, MVC itself, for instance, would not be able to handle errors happening in Auth. So, they came up with exception handling middleware that catches all the exceptions happening in middlewares registered down in the pipeline, pushes exception data into HttpContext.Features, and re-runs the pipeline for specified route (/error), allowing any middleware to handle this exception, and the best way to handle it is by our Controllers to maintain proper content negotiation.

AngularJS $watch window resize inside directive

// Following is angular 2.0 directive for window re size that adjust scroll bar for give element as per your tag

---- angular 2.0 window resize directive.
import { Directive, ElementRef} from 'angular2/core';

       selector: '[resize]',
       host: { '(window:resize)': 'onResize()' } // Window resize listener

export class AutoResize {

element: ElementRef; // Element that associated to attribute.
$window: any;
       constructor(_element: ElementRef) {

         this.element = _element;
         // Get instance of DOM window.
         this.$window = angular.element(window);



    // Adjust height of element.
    onResize() {
         $(this.element.nativeElement).css('height', (this.$window.height() - 163) + 'px');

Data truncation: Data too long for column 'logo' at row 1

Use data type LONGBLOB instead of BLOB in your database table.

Appending a byte[] to the end of another byte[]

You need to declare out as a byte array with a length equal to the lengths of ciphertext and mac added together, and then copy ciphertext over the beginning of out and mac over the end, using arraycopy.

byte[] concatenateByteArrays(byte[] a, byte[] b) {
    byte[] result = new byte[a.length + b.length]; 
    System.arraycopy(a, 0, result, 0, a.length); 
    System.arraycopy(b, 0, result, a.length, b.length); 
    return result;

How to unpack and pack pkg file?

@shrx I've succeeded to unpack the BSD.pkg (part of the Yosemite installer) by using "pbzx" command.

pbzx <pkg> | cpio -idmu

The "pbzx" command can be downloaded from the following link:

Windows batch: echo without new line

Use EchoX.EXE from the terrific "Shell Scripting Toolkit" by Bill Stewart
How to suppress the linefeed in a Windows Cmd script:

@Echo Off
Rem Print three Echos in one line of output
EchoX -n "Part 1 - "
EchoX -n "Part 2 - "
EchoX    "Part 3"


Part 1 - Part 2 - Part 3
{empty line}

The help for this usage is:

Usage: echox [-n] message
  -n       Do not skip to the next line.
  message  The text to be displayed.

The utility is smaller than 48K, and should live in your Path. More things it can do:
- print text without moving to the next line
- print text justified to the left, center, or right, within a certain width
- print text with Tabs, Linefeeds, and Returns
- print text in foreground and background colors

The Toolkit includes twelve more great scripting tricks.
The download page also hosts three other useful tool packages.

Plot inline or a separate window using Matplotlib in Spyder IDE


%matplotlib qt

when you want graphs in a separate window and

%matplotlib inline

when you want an inline plot

How to create a global variable?

Global variables that are defined outside of any method or closure can be scope restricted by using the private keyword.

import UIKit

// MARK: Local Constants

private let changeSegueId = "MasterToChange"
private let bookSegueId   = "MasterToBook"

What is the difference between JOIN and JOIN FETCH when using JPA and Hibernate

In this two queries, you are using JOIN to query all employees that have at least one department associated.

But, the difference is: in the first query you are returning only the Employes for the Hibernate. In the second query, you are returning the Employes and all Departments associated.

So, if you use the second query, you will not need to do a new query to hit the database again to see the Departments of each Employee.

You can use the second query when you are sure that you will need the Department of each Employee. If you not need the Department, use the first query.

I recomend read this link if you need to apply some WHERE condition (what you probably will need): How to properly express JPQL "join fetch" with "where" clause as JPA 2 CriteriaQuery?


If you don't use fetch and the Departments continue to be returned, is because your mapping between Employee and Department (a @OneToMany) are setted with FetchType.EAGER. In this case, any HQL (with fetch or not) query with FROM Employee will bring all Departments. Remember that all mapping *ToOne (@ManyToOne and @OneToOne) are EAGER by default.

How to write a:hover in inline CSS?

According to your comments, you're sending a JavaScript file anyway. Do the rollover in JavaScript. jQuery's $.hover() method makes it easy, as does every other JavaScript wrapper. It's not too hard in straight JavaScript either.

android - listview get item view by position

You can get only visible View from ListView because row views in ListView are reuseable. If you use mListView.getChildAt(0) you get first visible view. This view is associated with item from adapter at position mListView.getFirstVisiblePosition().

Python: slicing a multi-dimensional array

If you use numpy, this is easy:

slice = arr[:2,:2]

or if you want the 0's,

slice = arr[0:2,0:2]

You'll get the same result.

*note that slice is actually the name of a builtin-type. Generally, I would advise giving your object a different "name".

Another way, if you're working with lists of lists*:

slice = [arr[i][0:2] for i in range(0,2)]

(Note that the 0's here are unnecessary: [arr[i][:2] for i in range(2)] would also work.).

What I did here is that I take each desired row 1 at a time (arr[i]). I then slice the columns I want out of that row and add it to the list that I'm building.

If you naively try: arr[0:2] You get the first 2 rows which if you then slice again arr[0:2][0:2], you're just slicing the first two rows over again.

*This actually works for numpy arrays too, but it will be slow compared to the "native" solution I posted above.

Printing a char with printf

Yes, it prints GARBAGE unless you are lucky.


The type of the printf/sprintf/fprintf argument MUST match the associated format type char.

If the types don't match and it compiles, the results are very undefined.

Many newer compilers know about printf and issue warnings if the types do not match. If you get these warnings, FIX them.

If you want to convert types for arguments for variable functions, you must supply the cast (ie, explicit conversion) because the compiler can't figure out that a conversion needs to be performed (as it can with a function prototype with typed arguments).

printf("%d\n", (int) ch)

In this example, printf is being TOLD that there is an "int" on the stack. The cast makes sure that whatever thing sizeof returns (some sort of long integer, usually), printf will get an int.

printf("%d", (int) sizeof('\n'))

Apply Calibri (Body) font to text

There is no such font as “Calibri (Body)”. You probably saw this string in Microsoft Word font selection menu, but it’s not a font name (see e.g. the explanation Font: +body (in W07)).

So use just font-family: Calibri or, better, font-family: Calibri, sans-serif. (There is no adequate backup font for Calibri, but the odds are that when Calibri is not available, the browser’s default sans-serif font suits your design better than the browser’s default font, which is most often a serif font.)

How do you convert CString and std::string std::wstring to each other?

from this post (Thank you Mark Ransom )

Convert CString to string (VC6)

I have tested this and it works fine.

std::string Utils::CString2String(const CString& cString) 
    std::string strStd;

    for (int i = 0;  i < cString.GetLength();  ++i)
        if (cString[i] <= 0x7f)
            strStd.append(1, static_cast<char>(cString[i]));
            strStd.append(1, '?');

    return strStd;

How to do a join in linq to sql with method syntax?

var result = from sc in enumerableOfSomeClass
             join soc in enumerableOfSomeOtherClass
             on sc.Property1 equals soc.Property2
             select new { SomeClass = sc, SomeOtherClass = soc };

Would be equivalent to:

var result = enumerableOfSomeClass
          sc => sc.Property1,
          soc => soc.Property2,
          (sc, soc) => new
                           SomeClass = sc,
                           SomeOtherClass = soc

As you can see, when it comes to joins, query syntax is usually much more readable than lambda syntax.

How to download a folder from github?

You can use Github Contents API to get an archive link and tar to retrieve a specified folder.

Command line:

curl[owner]/[repo]/tar.gz/master | \ tar -xz --strip=2 [repo]-master/[folder_path]

For example,
if you want to download examples/with-apollo/ folder from zeit/next.js, you can type this:

curl | \
  tar -xz --strip=2 next.js-master/examples/with-apollo

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured

If datasource is defined in application.resources, make sure it is locate right under src/main and add it to the build path.

GROUP BY to combine/concat a column

A good question. Should tell you it took some time to crack this one. Here is my result.


VALUES  (1, 'Me', 'act1', 'ab'),
        (2, 'Me', 'act1', 'cd'),
        (3, 'You', 'act2', 'xy'),
        (4, 'You', 'act2', 'st')

        SELECT ',' + T2.PAGEURL  
        FROM @TABLE T2  
        WHERE T1.USERS = T2.USERS  
        FOR XML PATH ('')  

How to assign string to bytes array

Ended up creating array specific methods to do this. Much like the encoding/binary package with specific methods for each int type. For example binary.BigEndian.PutUint16([]byte, uint16).

func byte16PutString(s string) [16]byte {
    var a [16]byte
    if len(s) > 16 {
        copy(a[:], s)
    } else {
        copy(a[16-len(s):], s)
    return a

var b [16]byte
b = byte16PutString("abc")
fmt.Printf("%v\n", b)


[0 0 0 0 0 0 0 0 0 0 0 0 0 97 98 99]

Notice how I wanted padding on the left, not the right.

Why am I getting ImportError: No module named pip ' right after installing pip?

Just be sure that you have include python to windows PATH variable, then run python -m ensurepip

Can I execute a function after setState is finished updating?

Making setState return a Promise

In addition to passing a callback to setState() method, you can wrap it around an async function and use the then() method -- which in some cases might produce a cleaner code:

(async () => new Promise(resolve => this.setState({dummy: true}), resolve)()
    .then(() => { console.log('state:', this.state) });

And here you can take this one more step ahead and make a reusable setState function that in my opinion is better than the above version:

const promiseState = async state =>
    new Promise(resolve => this.setState(state, resolve));

    .then(() => promiseState({...})
    .then(() => {
        ...  // other code
        return promiseState({...});
    .then(() => {...});

This works fine in React 16.4, but I haven't tested it in earlier versions of React yet.

Also worth mentioning that keeping your callback code in componentDidUpdate method is a better practice in most -- probably all, cases.

MSIE and addEventListener Problem in Javascript?

As PPK points out here, in IE you can also use

e.cancelBubble = true;

Ignore fields from Java object dynamically while sending as JSON from Spring MVC

I have created a JsonUtil which can be used to ignore fields at runtime while giving a response.

Example Usage : First argument should be any POJO class (Student) and ignoreFields is comma seperated fields you want to ignore in response.

 Student st = new Student();

import java.util.logging.Logger;


public class JsonUtil {

  public static String createJsonIgnoreFields(Object object, String ignoreFields) {
     try {
         ObjectMapper mapper = new ObjectMapper();
         mapper.getSerializationConfig().addMixInAnnotations(Object.class, JsonPropertyFilterMixIn.class);
         String[] ignoreFieldsArray = ignoreFields.split(",");
         FilterProvider filters = new SimpleFilterProvider()
             .addFilter("filter properties by field names",
         ObjectWriter writer = mapper.writer().withFilters(filters);
         return writer.writeValueAsString(object);
     } catch (Exception e) {
         //handle exception here
     return "";

   public static String createJson(Object object) {
        try {
         ObjectMapper mapper = new ObjectMapper();
         ObjectWriter writer = mapper.writer().withDefaultPrettyPrinter();
         return writer.writeValueAsString(object);
        }catch (Exception e) {
         //handle exception here
        return "";

Delete commit on gitlab

We've had similar problem and it was not enough to only remove commit and force push to GitLab.
It was still available in GitLab interface using url:<group>/<project>/commit/<commit hash>

We've had to remove project from GitLab and recreate it to get rid of this commit in GitLab UI.

Android Studio drawable folders

Actually you have selected Android from the tab change it to project.


enter image description here

Then you will found all folders.

enter image description here

Java for loop syntax: "for (T obj : objects)"

for each S3ObjecrSummary in objectListing.getObjectSummaries()

it's looping through each item in the collection

android splash screen sizes for ldpi,mdpi, hdpi, xhdpi displays ? - eg : 1024X768 pixels for ldpi

There can be any number of different screen sizes due to Android having no set standard size so as a guide you can use the minimum screen sizes, which are provided by Google.

According to Google's statistics the majority of ldpi displays are small screens and the majority of mdpi, hdpi, xhdpi and xxhdpi displays are normal sized screens.

  • xlarge screens are at least 960dp x 720dp
  • large screens are at least 640dp x 480dp
  • normal screens are at least 470dp x 320dp
  • small screens are at least 426dp x 320dp

You can view the statistics on the relative sizes of devices on Google's dashboard which is available here.

More information on multiple screens can be found here.

9 Patch image

The best solution is to create a nine-patch image so that the image's border can stretch to fit the size of the screen without affecting the static area of the image.

Batch script to find and replace a string in text file within a minute for files up to 12 MB

How about this?

set search=%1
set replace=%2
set textfile=Input.txt    

python -c "with open('%textfile%', 'rw') as f: f.write('%search%', '%replace%'))"


How can I recursively find all files in current and subfolders based on wildcard matching?

find -L . -name "foo*"

In a few cases, I have needed the -L parameter to handle symbolic directory links. By default symbolic links are ignored. In those cases it was quite confusing as I would change directory to a sub-directory and see the file matching the pattern but find would not return the filename. Using -L solves that issue. The symbolic link options for find are -P -L -H

How to get the 'height' of the screen using jquery


To set anything in the middle you can use CSS.

    position: absolute;
    left: 50%;
    top: 50%;
    width: 300px;
    height: 400px;
    margin-left: -150px;
    margin-top: -200px;
<div id="divCentre">I am at the centre</div>

How do I pass JavaScript values to Scriptlet in JSP?

If you are saying you wanna pass javascript value from one jsp to another in javascript then use URLRewriting technique to pass javascript variable to next jsp file and access that in next jsp in request object.

Other wise you can't do it.

How to plot a subset of a data frame in R?

This chunk should do the work:

plot(var2 ~ var1, data=subset(dataframe, var3 < 150))

My best regards.

How this works:

  1. Fisrt, we make selection using the subset function. Other possibilities can be used, like, subset(dataframe, var4 =="some" & var5 > 10). The "&" operator can be used to select all "some" and over 10. Also the operator "|" could be used to select "some" or "over 10".
  2. The next step is to plot the results of the subset, using tilde (~) operator, that just imply a formula, in this case var.response ~ var.independet. Of course this is not a formula, but works great for this case.

Adding rows to dataset

To add rows to existing DataTable in Dataset:

DataRow drPartMtl = DSPartMtl.Tables[0].NewRow();
drPartMtl["Group"] = "Group";
drPartMtl["BOMPart"] = "BOMPart";

What is the best free SQL GUI for Linux for various DBMS systems

I tried many GUI's, and the best for me continue being "SQLyog-comunity" by using wine. Is complete, is nice, and is intuitive. (and in wine work perfect)

Visual Studio Error: (407: Proxy Authentication Required)

This helped in my case :

  1. close VS instance
  2. open Control Panel\User Accounts\Credential Manager
  3. Remove TFS related credentials from vault

This is just a hack. You need to do it regulary ... :-(

Best regards,


How to get first two characters of a string in oracle query?

SUBSTR (documentation):

SELECT SUBSTR(OrderNo, 1, 2) As NewColumnName from shipment

When selected, it's like any other column. You should give it a name (with As keyword), and you can selected other columns in the same statement:

SELECT SUBSTR(OrderNo, 1, 2) As NewColumnName, column2, ... from shipment

Running windows shell commands with python

import subprocess
result = []
win_cmd = 'ipconfig'(curr_user,filename,ip_address)
process = subprocess.Popen(win_cmd,
stderr=subprocess.PIPE )
for line in process.stdout:
    print line
errcode = process.returncode
for line in result:
    print line

How to create a .gitignore file

1. Open git terminal
2. go to git repository of the project
3. create a .gitignore file by **touch .gitignore** command
4. **git add .gitignore** command to add ignore file
5. set ignore rules in the ignore file
6. run the command **cat .gitignore**

By running the command in step 3 you will get the .gitignore file in the project directory. Thanks.

Text overwrite in visual studio 2010

None of the solutions above were working for me. My workaround was to open the on-screen keyboard using the system settings (press Windows key and search for "keyboard" to find them). Once that's open you can click the Insert key on it.

How to make the first option of <select> selected with jQuery

$("#target").val($("#target option:first").val());

Link a .css on another folder

I dont get it clearly, do you want to link an external css as the structure of files you defined above? If yes then just use the link tag :

    <link rel="stylesheet" type="text/css" href="file.css">

so basically for files that are under your website folder (folder containing your index) you directly call it. For each successive folder use the "/" for example in your case :

    <link rel="stylesheet" type="text/css" href="Fonts/Font1/file name">
    <link rel="stylesheet" type="text/css" href="Fonts/Font2/file name">

How to use makefiles in Visual Studio?

If you are asking about actual command line makefiles then you can export a makefile, or you can call MSBuild on a solution file from the command line. What exactly do you want to do with the makefile?

You can do a search on SO for MSBuild for more details.

How can I retrieve Id of inserted entity using Entity framework?

I had been using Ladislav Mrnka's answer to successfully retrieve Ids when using the Entity Framework however I am posting here because I had been miss-using it (i.e. using it where it wasn't required) and thought I would post my findings here in-case people are looking to "solve" the problem I had.

Consider an Order object that has foreign key relationship with Customer. When I added a new customer and a new order at the same time I was doing something like this;

var customer = new Customer(); //no Id yet;
var order = new Order(); //requires Customer.Id to link it to customer;
context.SaveChanges();//this generates the Id for customer
order.CustomerId = customer.Id;//finally I can set the Id

However in my case this was not required because I had a foreign key relationship between customer.Id and order.CustomerId

All I had to do was this;

var customer = new Customer(); //no Id yet;
var order = new Order{Customer = customer}; 
context.SaveChanges();//adds customer.Id to customer and the correct CustomerId to order

Now when I save the changes the id that is generated for customer is also added to order. I've no need for the additional steps

I'm aware this doesn't answer the original question but thought it might help developers who are new to EF from over-using the top-voted answer for something that may not be required.

This also means that updates complete in a single transaction, potentially avoiding orphin data (either all updates complete, or none do).

Express-js can't GET my static files, why?

if your setup

  |__ public
  |     |
  |     |__  stylesheets
  |     |     |
  |     |     |__ style.css
  |     |
  |     |___ img
  |           |
  |           |__ logo.png
  |__ app.js

put in app.js

app.use('/static', express.static('public'));

and refer to your style.css: (in some .pug file):

link(rel='stylesheet', href='/static/stylesheets/style.css')

Bootstrap 3: How to get two form inputs on one line and other inputs on individual lines?

I resorted to creating 2 style cascades using inline-block for input that pretty much override the field:

.input-sm {
    height: 2.1em;
    display: inline-block;

and a series of fixed sizes as opposed to %

.input-10 {
    width: 10em;

.input-32 {
    width: 32em;

How to assign a NULL value to a pointer in python?

Normally you can use None, but you can also use objc.NULL, e.g.

import objc
val = objc.NULL

Especially useful when working with C code in Python.

Also see: Python objc.NULL Examples

Disable text input history

<input type="text" autocomplete="off" />

What does `unsigned` in MySQL mean and when to use it?

MySQL says:

All integer types can have an optional (nonstandard) attribute UNSIGNED. Unsigned type can be used to permit only nonnegative numbers in a column or when you need a larger upper numeric range for the column. For example, if an INT column is UNSIGNED, the size of the column's range is the same but its endpoints shift from -2147483648 and 2147483647 up to 0 and 4294967295.

When do I use it ?

Ask yourself this question: Will this field ever contain a negative value?
If the answer is no, then you want an UNSIGNED data type.

A common mistake is to use a primary key that is an auto-increment INT starting at zero, yet the type is SIGNED, in that case you’ll never touch any of the negative numbers and you are reducing the range of possible id's to half.

How can I find whitespace in a String?

public static void main(String[] args) {
    System.out.println("test word".contains(" "));

Using ZXing to create an Android barcode scanning app

If you want to include into your code and not use the IntentIntegrator that the ZXing library recommend, you can use some of these ports:

I use the first, and it works perfectly! It has a sample project to try it on.

Adding asterisk to required fields in Bootstrap 3

I modified the css, as i am using bootstrap 3.3.6

.form-group.required label:after{   
color: #d00;   
font-family: 'FontAwesome'; 
font-weight: normal;
font-size: 10px;
content: "\f069"; 
position: absolute;   
 margin-left: 8px;

the HTML

<div class="form-group required">
 <label for="return_notes"><?= _lang('notes') ?></label>
 <textarea class="form-control" name="return_notes" id="return_notes"  required="required"></textarea>

Executing set of SQL queries using batch file?

Different ways:

  1. Using SQL Server Agent (If local instance)
    schedule a job in sql server agent with a new step having type as "T-SQL" then run the job.

  2. Using SQLCMD
    To use SQLCMD refer

  3. Using SQLPS
    To use SQLPS refer

How to remove duplicate values from an array in PHP

$arr1 = [1,1,2,3,4,5,6,3,1,3,5,3,20];    

function arr_unique($arr) {
  $curr = $arr[0];
  $uni_arr[] = $arr[0];
  for($i=0; $i<count($arr);$i++){
      if($curr != $arr[$i]) {
        $uni_arr[] = $arr[$i];
        $curr = $arr[$i];
  return $uni_arr;

Class file has wrong version 52.0, should be 50.0

i faced the same problem "Class file has wrong version 52.0, should be 50.0" when running java through ant... all i did was add fork="true" wherever i used the javac task and it worked...

@font-face not working

I was developing for an Arabic client, and had an issue like this as well, after using a font generator to create my fonts. None of the fonts I was generating were working.

It turns out that there was a setting in the "Advanced options" of the genrator which I needed to select which would not only use a the Western language glyphs (a pre-selected option).

After removing this subset, my fonts then worked with the Arabic characters. I hope this may help someone else in this position.


Bad operand type for unary +: 'str'

The code works for me. (after adding missing except clause / import statements)

Did you put \ in the original code?

urlToVisit = '' \
              + stock + '/chartdata;type=quote;range=5d/csv'

If you omit it, it could be a cause of the exception:

>>> stock = 'GOOG'
>>> urlToVisit = ''
>>> + stock + '/chartdata;type=quote;range=5d/csv'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: bad operand type for unary +: 'str'

BTW, string(e) should be str(e).

How to deserialize xml to object

Your classes should look like this

public class StepList
    public List<Step> Steps { get; set; }

public class Step
    public string Name { get; set; }
    public string Desc { get; set; }

Here is my testcode.

string testData = @"<StepList>

XmlSerializer serializer = new XmlSerializer(typeof(StepList));
using (TextReader reader = new StringReader(testData))
    StepList result = (StepList) serializer.Deserialize(reader);

If you want to read a text file you should load the file into a FileStream and deserialize this.

using (FileStream fileStream = new FileStream("<PathToYourFile>", FileMode.Open)) 
    StepList result = (StepList) serializer.Deserialize(fileStream);

Turn off constraints temporarily (MS SQL)

You can disable FK and CHECK constraints only in SQL 2005+. See ALTER TABLE




Primary keys and unique constraints can not be disabled, but this should be OK if I've understood you correctly.

Reducing MongoDB database file size

Database files cannot be reduced in size. While "repairing" database, it is only possible for mongo server to delete some of its files. If large amount of data has been deleted, mongo server will "release" (delete), during repair, some of its existing files.

Unable to locate Spring NamespaceHandler for XML schema namespace []

In my case, this was caused by custom manifest entries added by the maven-jar-plugin.


Removing the following entries fixed the problem


Delete all but the most recent X files in bash

If the filenames don't have spaces, this will work:

ls -C1 -t| awk 'NR>5'|xargs rm

If the filenames do have spaces, something like

ls -C1 -t | awk 'NR>5' | sed -e "s/^/rm '/" -e "s/$/'/" | sh

Basic logic:

  • get a listing of the files in time order, one column
  • get all but the first 5 (n=5 for this example)
  • first version: send those to rm
  • second version: gen a script that will remove them properly

CSS3 Fade Effect

The scrolling effect is cause by specifying the generic 'background' property in your css instead of the more specific background-image. By setting the background property, the animation will transition between all properties.. Background-Color, Background-Image, Background-Position.. Etc Thus causing the scrolling effect..


a {
-webkit-transition-property: background-image 300ms ease-in 200ms;
-moz-transition-property: background-image 300ms ease-in 200ms;
-o-transition-property: background-image 300ms ease-in 200ms;
transition: background-image 300ms ease-in 200ms;

How to set a Postgresql default value datestamp like 'YYYYMM'?

Right. Better to use a function:

    LANGUAGE 'plpgsql' AS $$
    retval text;
    m integer;
    retval := EXTRACT(year from current_timestamp);
    m := EXTRACT(month from current_timestamp);
    IF m < 10 THEN retval := retval || '0'; END IF;
    RETURN retval || m;
END $$;

SELECT yyyymm();

    key             int PRIMARY KEY,
    colname text DEFAULT yyyymm()
INSERT INTO foo (key) VALUES (0);

This gives me

 key | colname 
   0 | 200905

Make sure you run createlang plpgsql from the Unix command line, if necessary.

Add Twitter Bootstrap icon to Input box

Since the glyphicons image is a sprite, you really can't do that: fundamentally what you want is to limit the size of the background, but there's no way to specify how big the background is. Either you cut out the icon you want, size it down and use it, or use something like the input field prepend/append option ( and then search for prepended inputs).

right align an image using CSS HTML

 img {
     display: block;
     margin-left: auto;

Android - Center TextView Horizontally in LinearLayout

Use android:gravity="center" in TextView instead of layout_gravity.

Convert a string to integer with decimal in Python

The expression int(float(s)) mentioned by others is the best if you want to truncate the value. If you want rounding, using int(round(float(s)) if the round algorithm matches what you want (see the round documentation), otherwise you should use Decimal and one if its rounding algorithms.

Generating a random hex color code with PHP

As of PHP 5.3, you can use openssl_random_pseudo_bytes():

$hex_string = bin2hex(openssl_random_pseudo_bytes(3));

How to get JSON response from http.Get

The ideal way is not to use ioutil.ReadAll, but rather use a decoder on the reader directly. Here's a nice function that gets a url and decodes its response onto a target structure.

var myClient = &http.Client{Timeout: 10 * time.Second}

func getJson(url string, target interface{}) error {
    r, err := myClient.Get(url)
    if err != nil {
        return err
    defer r.Body.Close()

    return json.NewDecoder(r.Body).Decode(target)

Example use:

type Foo struct {
    Bar string

func main() {
    foo1 := new(Foo) // or &Foo{}
    getJson("", foo1)

    // alternately:

    foo2 := Foo{}
    getJson("", &foo2)

You should not be using the default *http.Client structure in production as this answer originally demonstrated! (Which is what http.Get/etc call to). The reason is that the default client has no timeout set; if the remote server is unresponsive, you're going to have a bad day.

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

From at least, the 2.0 version, Spring-Data-Jpa modified findOne().
Now, findOne() has neither the same signature nor the same behavior.
Previously, it was defined in the CrudRepository interface as:

T findOne(ID primaryKey);

Now, the single findOne() method that you will find in CrudRepository is the one defined in the QueryByExampleExecutor interface as:

<S extends T> Optional<S> findOne(Example<S> example);

That is implemented finally by SimpleJpaRepository, the default implementation of the CrudRepository interface.
This method is a query by example search and you don't want that as a replacement.

In fact, the method with the same behavior is still there in the new API, but the method name has changed.
It was renamed from findOne() to findById() in the CrudRepository interface :

Optional<T> findById(ID id); 

Now it returns an Optional, which is not so bad to prevent NullPointerException.

So, the actual method to invoke is now Optional<T> findById(ID id).

How to use that?
Learning Optional usage. Here's important information about its specification:

A container object which may or may not contain a non-null value. If a value is present, isPresent() will return true and get() will return the value.

Additional methods that depend on the presence or absence of a contained value are provided, such as orElse() (return a default value if value not present) and ifPresent() (execute a block of code if the value is present).

Some hints on how to use Optional with Optional<T> findById(ID id).

Generally, as you look for an entity by id, you want to return it or make a particular processing if that is not retrieved.

Here are three classical usage examples.

  1. Suppose that if the entity is found you want to get it otherwise you want to get a default value.

You could write :

Foo foo = repository.findById(id)
                    .orElse(new Foo());

or get a null default value if it makes sense (same behavior as before the API change) :

Foo foo = repository.findById(id)
  1. Suppose that if the entity is found you want to return it, else you want to throw an exception.

You could write :

return repository.findById(id)
        .orElseThrow(() -> new EntityNotFoundException(id));
  1. Suppose you want to apply a different processing according to if the entity is found or not (without necessarily throwing an exception).

You could write :

Optional<Foo> fooOptional = fooRepository.findById(id);
if (fooOptional.isPresent()) {
    Foo foo = fooOptional.get();
    // processing with foo ...
} else {
    // alternative processing....

subquery in FROM must have an alias

add an ALIAS on the subquery,

SELECT  COUNT(made_only_recharge) AS made_only_recharge
        SELECT DISTINCT (identifiant) AS made_only_recharge
        FROM cdr_data
        WHERE CALLEDNUMBER = '0130'
        SELECT DISTINCT (identifiant) AS made_only_recharge
        FROM cdr_data
        WHERE CALLEDNUMBER != '0130'
    ) AS derivedTable                           -- <<== HERE

HTML img tag: title attribute vs. alt attribute?

I believe alt is required for strict XHTML compliance.

As others have noted, title is for tooltips (nice to have), alt is for accessibility. Nothing wrong with using both, but alt should always be there.

How to add a line break in an Android TextView?

Android version 1.6 does not recognize \r\n. Instead, use: System.getProperty ("line.separator")

String s = "Line 1"
           + System.getProperty ("line.separator")
           + "Line 2"
           + System.getProperty ("line.separator");

How to import and use image in a Vue single file component?

These both work for me in JavaScript and TypeScript

<img src="@/assets/images/logo.png" alt=""> 


 <img src="./assets/images/logo.png" alt="">

What is stdClass in PHP?

stdClass is not an anonymous class or anonymous object

Answers here includes expressions that stdClass is an anonymous class or even anonymous object. It's not a true.

stdClass is just a regular predefined class. You can check this using instanceof operator or function get_class. Nothing special goes here. PHP uses this class when casting other values to object.

In many cases where stdClass is used by the programmers the array is better option, because of useful functions and the fact that this usecase represents the data structure not a real object.

Laravel: Get Object From Collection By Attribute

Since I don't need to loop entire collection, I think it is better to have helper function like this

 * Check if there is a item in a collection by given key and value
 * @param Illuminate\Support\Collection $collection collection in which search is to be made
 * @param string $key name of key to be checked
 * @param string $value value of key to be checkied
 * @return boolean|object false if not found, object if it is found
function findInCollection(Illuminate\Support\Collection $collection, $key, $value) {
    foreach ($collection as $item) {
        if (isset($item->$key) && $item->$key == $value) {
            return $item;
    return FALSE;

How to automatically indent source code?

In 2010 it is Ctrl+k, Ctrl+d. See image below.

enter image description here

Simplest code for array intersection in javascript

function getIntersection(arr1, arr2){
    var result = [];
            if(elem === elem2){
    return result;

getIntersection([1,2,3], [2,3,4,5]); // [ 2, 3 ]

Retrieve a Fragment from a ViewPager

Ok for the adapter FragmentStatePagerAdapter I fund a solution :

in your FragmentActivity :

ActionBar mActionBar = getSupportActionBar(); 
mActionBar.addTab(mActionBar.newTab().setText("TAB1").setTabListener(this).setTag(Fragment.instantiate(this, MyFragment1.class.getName())));
mActionBar.addTab(mActionBar.newTab().setText("TAB2").setTabListener(this).setTag(Fragment.instantiate(this, MyFragment2.class.getName())));
mActionBar.addTab(mActionBar.newTab().setText("TAB3").setTabListener(this).setTag(Fragment.instantiate(this, MyFragment3.class.getName())));

viewPager = (STViewPager) super.findViewById(;
mPagerAdapter = new MyPagerAdapter(getSupportFragmentManager(), mActionBar);

and create a methode in your class FragmentActivity - So that method give you access to your Fragment, you just need to give it the position of the fragment you want:

public Fragment getActiveFragment(int position) {
String name = MyPagerAdapter.makeFragmentName(position);
return getSupportFragmentManager().findFragmentByTag(name);

in your Adapter :

public class MyPagerAdapter extends FragmentStatePagerAdapter {

private final ActionBar actionBar;
private final FragmentManager fragmentManager;

public MyPagerAdapter(FragmentManager fragmentManager, mActionBar) {super(fragmentManager);
this.actionBar = mActionBar;
this.fragmentManager = fragmentManager;

public Fragment getItem(int position) {
getSupportFragmentManager().beginTransaction().add(mTchatDetailsFragment, makeFragmentName(position)).commit();
return (Fragment)this.actionBar.getTabAt(position);

public int getCount() {
return this.actionBar.getTabCount();

public CharSequence getPageTitle(int position) {
return this.actionBar.getTabAt(position).getText();

private static String makeFragmentName(int viewId, int index) {
return "android:fragment:" + index;


YouTube API to fetch all videos on a channel

Using API version 2, which is deprecated, the URL for uploads (of channel UCqAEtEr0A0Eo2IVcuWBfB9g) is:

There is an API version 3.

Android - save/restore fragment state

If you using bottombar and insted of viewpager you want to set custom fragment replacement logic with retrieve previously save state you can do using below code

 String current_frag_tag = null;
 String prev_frag_tag = null;

    public void onTabSelected(TabLayout.Tab tab) {

        switch (tab.getPosition()) {
            case 0:

                replaceFragment(new Fragment1(), "Fragment1");

            case 1:
                replaceFragment(new Fragment2(), "Fragment2");

            case 2:
                replaceFragment(new Fragment3(), "Fragment3");

            case 3:
               replaceFragment(new Fragment4(), "Fragment4");

                replaceFragment(new Fragment1(), "Fragment1");


    public void replaceFragment(Fragment fragment, String tag) {
        if (current_frag_tag != null) {
            prev_frag_tag = current_frag_tag;

        current_frag_tag = tag;

        FragmentManager manager = null;
        try {
            manager = requireActivity().getSupportFragmentManager();
            FragmentTransaction ft = manager.beginTransaction();

            if (manager.findFragmentByTag(current_frag_tag) == null) { // No fragment in backStack with same tag..
                ft.add(, fragment, current_frag_tag);

                if (prev_frag_tag != null) {
                    try {
                    } catch (NullPointerException e) {
//  ;

            } else {

                try {
                } catch (NullPointerException e) {
        } catch (Exception e) {


Inside Child Fragments you can access fragment is visible or not using below method note: you have to implement below method in child fragment

    public void onHiddenChanged(boolean hidden) {

        try {
        }catch (Exception e){


How to load Spring Application Context

I am using in the way and it is working for me.

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


public CarpoolDBAppTest(){
    ApplicationContext context = new ClassPathXmlApplicationContext("application-context.xml");
    Student stud = (Student) context.getBean("yourBeanId");

Here Student is my classm you will get the class matching yourBeanId.

Now work on that object with whatever operation you want to do.

How to send list of file in a folder to a txt file in Linux

you can just use

ls > filenames.txt

(usually, start a shell by using "Terminal", or "shell", or "Bash".) You may need to use cd to go to that folder first, or you can ls ~/docs > filenames.txt

How can I initialize base class member variables in derived class constructor?

Leaving aside the fact that they are private, since a and b are members of A, they are meant to be initialized by A's constructors, not by some other class's constructors (derived or not).


class A
    int a, b;

protected: // or public:
    A(int a, int b): a(a), b(b) {}

class B : public A
    B() : A(0, 0) {}

What are the First and Second Level caches in (N)Hibernate?

First-level cache

Hibernate tries to defer the Persistence Context flushing up until the last possible moment. This strategy has been traditionally known as transactional write-behind.

The write-behind is more related to Hibernate flushing rather than any logical or physical transaction. During a transaction, the flush may occur multiple times.

enter image description here

The flushed changes are visible only for the current database transaction. Until the current transaction is committed, no change is visible by other concurrent transactions.

Due to the first-level cache, Hibernate can do several optimizations:

  • JDBC statement batching
  • prevent lost update anomalies

Second-level cache

A proper caching solution would have to span across multiple Hibernate Sessions and that’s the reason Hibernate supports an additional second-level cache as well.

The second-level cache is bound to the SessionFactory life-cycle, so it’s destroyed only when the SessionFactory is closed (typically when the application is shutting down). The second-level cache is primarily entity-based oriented, although it supports an optional query-caching solution as well.

When loading an entity, Hibernate will execute the following actions:

Entity load flow

  1. If the entity is stored in the first-level cache, then the cached object reference is returned. This ensures application-level repeatable reads.
  2. If the entity is not stored in the first-level cache and the second-level cache is activated, then Hibernate checks if the entity has been cached in the second-level cache, and if it were, it returns it to the caller.
  3. Otherwise, if the entity is not stored in the first or second-level cache, it will be loaded from the DB.

Excel date to Unix timestamp

Windows and Mac Excel (2011):

Unix Timestamp = (Excel Timestamp - 25569) * 86400
Excel Timestamp =  (Unix Timestamp / 86400) + 25569

MAC OS X (2007):

Unix Timestamp = (Excel Timestamp - 24107) * 86400
Excel Timestamp =  (Unix Timestamp / 86400) + 24107

For Reference:

86400 = Seconds in a day
25569 = Days between 1970/01/01 and 1900/01/01 (min date in Windows Excel)
24107 = Days between 1970/01/01 and 1904/01/02 (min date in Mac Excel 2007)

Is there any way of configuring Eclipse IDE proxy settings via an autoproxy configuration script?

Here is what I do. All of these instructions are based on my minimal experiences with working PACs, so YMMV.

Download your pac file via your pac URL. It's plain text and should be easy to open in a text editor.

Near the bottom, there's probably a section that says something like: return "PROXY w.x.y.z:a" where "w.x.y.z" is an ip address or username and "a" is a port number.

Write these down.

In a recent version of eclipse :

  • Go to Window -> Preferences -> General -> Network Connections=
  • Change the provider to "Manual"
  • Select the "HTTP" line and click the edit button
  • Add the IP address and port number above to the http line
  • If you have to authenticate to use the proxy,
    • select "Requires Authentication"
    • type in your username. Note that if your authentication is on a Windows domain, you might have to prepend the domain name and a backslash (\) like: MYDOMAIN\MYUSERID
    • Type in your password
  • Click OK
  • Click Apply
  • Click OK

At this point, you should be able to browse using the internal web browser (at least on http URLs).

Good luck.

Edit: Just so you know, it's WAY easier to use Nexus, one set of <mirror> tags and a single proxy setup (inside Nexus) to manage the proxy issues of Maven inside a firewall.

Docker - Container is not running

If it's not possible to start the main process again (for long enough), there is also the possibility to commit the container to a new image and run a new container from this image. While this is not the usual best practice workflow, I find it really useful to debug a failing script once in a while.

docker exec -it 6198ef53d943 bash
Error response from daemon: Container 6198ef53d9431a3f38e8b38d7869940f7fb803afac4a2d599812b8e42419c574 is not running

docker commit 6198ef53d943

docker run -it ace7ca65e6e bash

Ruby objects and JSON serialization (without Rails)

Check out Oj. There are gotchas when it comes to converting any old object to JSON, but Oj can do it.

require 'oj'

class A
    def initialize a=[1,2,3], b='hello'
        @a = a
        @b = b

a =
puts Oj::dump a, :indent => 2

This outputs:


Note that ^o is used to designate the object's class, and is there to aid deserialization. To omit ^o, use :compat mode:

puts Oj::dump a, :indent => 2, :mode => :compat



What is the difference between single-quoted and double-quoted strings in PHP?

In PHP, both 'my name' and "my name" are string. You can read more about it at the PHP manual.

Thing you should know are

$a = 'name';
$b = "my $a"; == 'my name'
$c = 'my $a'; != 'my name'

In PHP, people use single quote to define a constant string, like 'a', 'my name', 'abc xyz', while using double quote to define a string contain identifier like "a $b $c $d".

And other thing is,

echo 'my name';

is faster than

echo "my name";


echo 'my ' . $a;

is slower than

echo "my $a";

This is true for other used of string.

Converting a list to a set changes element order

In mathematics, there are sets and ordered sets (osets).

  • set: an unordered container of unique elements (Implemented)
  • oset: an ordered container of unique elements (NotImplemented)

In Python, only sets are directly implemented. We can emulate osets with regular dict keys (3.7+).


a = [1, 2, 20, 6, 210, 2, 1]
b = {2, 6}


oset = dict.fromkeys(a).keys()
# dict_keys([1, 2, 20, 6, 210])


Replicates are removed, insertion-order is preserved.

# [1, 2, 20, 6, 210]

Set-like operations on dict keys.

oset - b
# {1, 20, 210}

oset | b
# {1, 2, 5, 6, 20, 210}

oset & b
# {2, 6}

oset ^ b
# {1, 5, 20, 210}


Note: an unordered structure does not preclude ordered elements. Rather, maintained order is not guaranteed. Example:

assert {1, 2, 3} == {2, 3, 1}                    # sets (order is ignored)

assert [1, 2, 3] != [2, 3, 1]                    # lists (order is guaranteed)

One may be pleased to discover that a list and multiset (mset) are two more fascinating, mathematical data structures:

  • list: an ordered container of elements that permits replicates (Implemented)
  • mset: an unordered container of elements that permits replicates (NotImplemented)*


Container | Ordered | Unique | Implemented
set       |    n    |    y   |     y
oset      |    y    |    y   |     n
list      |    y    |    n   |     y
mset      |    n    |    n   |     n*  

*A multiset can be indirectly emulated with collections.Counter(), a dict-like mapping of multiplicities (counts).

Best way to represent a fraction in Java?

I'm trying to work with proper fractions in Java.

Apache Commons Math has had a Fraction class for quite some time. Most times the answer to, "Boy I wish Java had something like X in the core library!" can be found under the umbrella of the Apache Commons library.

Could not find any resources appropriate for the specified culture or the neutral culture

In my case a series of badly thought global text replacements had inadvertently changed this line in the resource designer cs file.

enter image description here

Since the namespace in that argument did not match the namespace of the class anymore, the application got confused at run time.

Check that the namespace of the designer matches the string argument in that line.

Serving favicon.ico in ASP.NET MVC

It should also be possible to create a controller that returns the ico file and register the route /favicon.ico to point to that controller.

Disabling the long-running-script message in Internet Explorer

I can't comment on the previous answers since I haven't tried them. However I know the following strategy works for me. It is a bit less elegant but gets the job done. It also doesn't require breaking code into chunks like some other approaches seem to do. In my case, that was not an option, because my code had recursive calls to the logic that was being looped; i.e., there was no practical way to just hop out of the loop, then be able to resume in some way by using global vars to preserve current state since those globals could be changed by references to them in a subsequent recursed call. So I needed a straight-forward way that would not offer a chance for the code to compromise the data state integrity.

Assuming the "stop script?" dialog is coming up during a for() loop executuion after a number of iterations (in my case, about 8-10), and messing with the registry is no option, here was the fix (for me, anyway):

var anarray = [];
var array_member = null;
var counter = 0; // Could also be initialized to the max desired value you want, if
                 // planning on counting downward.

function func_a()
 // some code
 // optionally, set 'counter' to some desired value.
 anarray = { populate array with objects to be processed that would have been
             processed by a for() }
 // 'anarry' is going to be reduced in size iteratively.  Therefore, if you need
 //  to maintain an orig. copy of it, create one, something like 'anarraycopy'.
 //  If you need only a shallow copy, use 'anarraycopy = anarray.slice(0);'
 //  A deep copy, depending on what kind of objects you have in the array, may be
 //  necessary.  The strategy for a deep copy will vary and is not discussed here.
 //  If you need merely to record the array's orig. size, set a local or
 //  global var equal to 'anarray.length;', depending on your needs.
 // - or -
 // plan to use 'counter' as if it was 'i' in a for(), as in
 // for(i=0; i < x; i++ {...}


   // Using 50 for example only.  Could be 100, etc. Good practice is to pick something
   // other than 0 due to Javascript engine processing; a 0 value is all but useless
   // since it takes time for Javascript to do anything. 50 seems to be good value to
   // use. It could be though that what value to use does  depend on how much time it
   // takes the code in func_c() to execute, so some profiling and knowing what the 
   // most likely deployed user base is going to be using might help. At the same 
   // time, this may make no difference.  Not entirely sure myself.  Also, 
   // using "'func_b()'" instead of just "func_b()" is critical.  I've found that the
   // callback will not occur unless you have the function in single-quotes.

   setTimeout('func_b()', 50);

  //  No more code after this.  function func_a() is now done.  It's important not to
  //  put any more code in after this point since setTimeout() does not act like
  //  Thread.sleep() in Java.  Processing just continues, and that is the problem
  //  you're trying to get around.

} // func_a()

function func_b()
 if( anarray.length == 0 )
   // possibly do something here, relevant to your purposes
//  -or- 
if( counter == x ) // 'x' is some value you want to go to.  It'll likely either
                   // be 0 (when counting down) or the max desired value you
                   // have for x if counting upward.
  // possibly do something here, relevant to your purposes

array_member = anarray[0];
anarray.splice(0,1); // Reduces 'anarray' by one member, the one at anarray[0].
                     // The one that was at anarray[1] is now at
                     // anarray[0] so will be used at the next iteration of func_b().


setTimeout('func_b()', 50);

} // func_b()

function func_c()
  counter++; // If not using 'anarray'.  Possibly you would use
             // 'counter--' if you set 'counter' to the highest value
             // desired and are working your way backwards.

  // Here is where you have the code that would have been executed
  // in the for() loop.  Breaking out of it or doing a 'continue'
  // equivalent can be done with using 'return;' or canceling 
  // processing entirely can be done by setting a global var
  // to indicate the process is cancelled, then doing a 'return;', as in
  // 'bCancelOut = true; return;'.  Then in func_b() you would be evaluating
  // bCancelOut at the top to see if it was true.  If so, you'd just exit from
  // func_b() with a 'return;'

} // func_c()

Django: save() vs update() to update the database?

Using update directly is more efficient and could also prevent integrity problems.

From the official documentation

If you’re just updating a record and don’t need to do anything with the model object, the most efficient approach is to call update(), rather than loading the model object into memory. For example, instead of doing this:

e = Entry.objects.get(id=10)
e.comments_on = False

…do this:


Using update() also prevents a race condition wherein something might change in your database in the short period of time between loading the object and calling save().

Autoresize View When SubViews are Added

Yes, it is because you are using auto layout. Setting the view frame and resizing mask will not work.

You should read Working with Auto Layout Programmatically and Visual Format Language.

You will need to get the current constraints, add the text field, adjust the contraints for the text field, then add the correct constraints on the text field.

Sorting an Array of int using BubbleSort

You need two loops to implement the Bubble Sort .

Sample code :

public static void bubbleSort(int[] numArray) {

    int n = numArray.length;
    int temp = 0;

    for (int i = 0; i < n; i++) {
        for (int j = 1; j < (n - i); j++) {

            if (numArray[j - 1] > numArray[j]) {
                temp = numArray[j - 1];
                numArray[j - 1] = numArray[j];
                numArray[j] = temp;


What is the default encoding of the JVM?

You can use this to print out the JVM defaults

import java.nio.charset.Charset;

public class PrintCharSets {
        public static void main(String[] args) throws Exception {
                System.out.println("file.encoding=" + System.getProperty("file.encoding"));
                System.out.println("Charset.defaultCharset=" + Charset.defaultCharset());
                System.out.println("InputStreamReader.getEncoding=" + new InputStreamReader(new FileInputStream("./")).getEncoding());

Compile and Run

javac && java PrintCharSets

ImportError: No module named xlsxwriter

I installed it by using a wheel file that can be found at this location:

I then ran pip install "XlsxWriter-1.2.8-py2.py3-none-any.whl"

Processing ./XlsxWriter-1.2.8-py2.py3-none-any.whl
Installing collected packages: XlsxWriter
Successfully installed XlsxWriter-1.2.8

How to add default value for html <textarea>?

You can use placeholder Attribute, which doesn't add a default value but might be what you are looking out for :

<textarea placeholder="this text will show in the textarea"></textarea>

Check it out here - enter image description here

Important Note ( As suggested by Jon Brave in the comments ) :

Placeholder Attribute does not set the value of a textarea. Rather "The placeholder attribute represents a short hint (a word or short phrase) intended to aid the user with data entry when the control has no value" [and it disappears as soon as user clicks into the textarea]. It will never act as "the default value" for the control. If you want that, you must put the desired text inside the Here is the actual default value, as per other answers here

How can I convert a date into an integer?

Using the builtin Date.parse function which accepts input in ISO8601 format and directly returns the desired integer return value:

var dates_as_int =;

MySQL ORDER BY rand(), name ASC

Instead of using a subquery, you could use two separate queries, one to get the number of rows and the other to select the random rows.

SELECT COUNT(id) FROM users; #id is the primary key

Then, get a random twenty rows.

$start_row = mt_rand(0, $total_rows - 20);

The final query:

SELECT * FROM users ORDER BY name ASC LIMIT $start_row, 20;

JQuery or JavaScript: How determine if shift key being pressed while clicking anchor tag hyperlink?

The keypress event isn't triggered by all browsers when you click shift or ctrl, but fortunately the keydown event is.

If you switch out the keypress with keydown you might have better luck.

How to find Current open Cursors in Oracle

This could work:

SELECT    sql_text "SQL Query", 
          Count(*) AS "Open Cursors" 
FROM      v$open_cursor 
GROUP BY  sql_text 
HAVING    Count(*) > 2 
ORDER BY  Count(*) DESC; 

PHP Session Destroy on Log Out Button

The folder being password protected has nothing to do with PHP!

The method being used is called "Basic Authentication". There are no cross-browser ways to "logout" from it, except to ask the user to close and then open their browser...

Here's how you you could do it in PHP instead (fully remove your Apache basic auth in .htaccess or wherever it is first):


//change 'valid_username' and 'valid_password' to your desired "correct" username and password
if (! empty($_POST) && $_POST['user'] === 'valid_username' && $_POST['pass'] === 'valid_password')
    $_SESSION['logged_in'] = true;
    header('Location: /index.php');

    <form method="POST">
    Username: <input name="user" type="text"><br>
    Password: <input name="pass" type="text"><br><br>
    <input type="submit" value="submit">



if (! empty($_SESSION['logged_in']))

    <p>here is my super-secret content</p>
    <a href='logout.php'>Click here to log out</a>

    echo 'You are not logged in. <a href="login.php">Click here</a> to log in.';


echo 'You have been logged out. <a href="/">Go back</a>';

Obviously this is a very basic implementation. You'd expect the usernames and passwords to be in a database, not as a hardcoded comparison. I'm just trying to give you an idea of how to do the session thing.

Hope this helps you understand what's going on.

How are Anonymous inner classes used in Java?

One more advantage:
As you know that Java doesn't support multiple inheritance, so if you use "Thread" kinda class as anonymous class then the class still has one space left for any other class to extend.

How to make a script wait for a pressed key?

I am new to python and I was already thinking I am too stupid to reproduce the simplest suggestions made here. It turns out, there's a pitfall one should know:

When a python-script is executed from IDLE, some IO-commands seem to behave completely different (as there is actually no terminal window).

Eg. msvcrt.getch is non-blocking and always returns $ff. This has already been reported long ago (see e.g. ) - and it's marked as fixed, somehow the problem seems to persist in current versions of python/IDLE.

So if any of the code posted above doesn't work for you, try running the script manually, and NOT from IDLE.

Accessing Google Account Id /username via Android

There is a sample from google, which lists the existing google accounts and generates an access token upon selection , you can send that access token to server to retrieve the related details from it to identify the user.

You can also get the email id from access token , for that you need to modify the SCOPE

Please go through My Post

How can I Insert data into SQL Server using VBNet

Imports System.Data

Imports System.Data.SqlClient

Public Class Form2

Dim myconnection As SqlConnection

Dim mycommand As SqlCommand

Dim dr As SqlDataReader

Dim dr1 As SqlDataReader

Dim ra As Integer

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    myconnection = New SqlConnection("server=localhost;uid=root;pwd=;database=simple")

    'you need to provide password for sql server


    mycommand = New SqlCommand("insert into tbl_cus([name],[class],[phone],[address]) values ('" & TextBox1.Text & "','" & TextBox2.Text & "','" & TextBox3.Text & "','" & TextBox4.Text & "')", myconnection)


    MessageBox.Show("New Row Inserted" & ra)


End Sub

End Class

How can I run a directive after the dom has finished rendering?

Probably the author won't need my answer anymore. Still, for sake of completeness i feel other users might find it useful. The best and most simple solution is to use $(window).load() inside the body of the returned function. (alternatively you can use document.ready. It really depends if you need all the images or not).

Using $timeout in my humble opinion is a very weak option and may fail in some cases.

Here is the complete code i'd use:

.directive('directiveExample', function(){
   return {
       restrict: 'A',
       link: function($scope, $elem, attrs){

           $(window).load(function() {
               //...JS here...

How do I reference a local image in React?

First of all wrap the src in {}

Then if using Webpack; Instead of: <img src={"./logo.jpeg"} />

You may need to use require:

<img src={require('./logo.jpeg')} />

Another option would be to first import the image as such:

import logo from './logo.jpeg'; // with import

or ...

const logo = require('./logo.jpeg); // with require

then plug it in...

<img src={logo} />

I'd recommend this option especially if you're reusing the image source.

Where can I find Android source code online?

Everything is mirrored on Some of the code is also mirrored on github.

Contacts is here for example.

Since December 2019, you can use the new official public code search tool for AOSP: There's also the Android official source browser (based on Gitiles) has a web view of many of the different parts that make up android. Some of the projects (such as Kernel) have been removed and it now only points you to clonable git repositories.

To get all the code locally, you can use the repo helper program, or you can just clone individual repositories.

And others:

Display Records From MySQL Database using JTable in Java

Below is a class which will accomplish the very basics of what you want to do when reading data from a MySQL database into a JTable in Java.

import java.awt.*;
import java.sql.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

public class TableFromMySqlDatabase extends JFrame
    public TableFromMySqlDatabase()
        ArrayList columnNames = new ArrayList();
        ArrayList data = new ArrayList();

        //  Connect to an MySQL Database, run query, get result set
        String url = "jdbc:mysql://localhost:3306/yourdb";
        String userid = "root";
        String password = "sesame";
        String sql = "SELECT * FROM animals";

        // Java SE 7 has try-with-resources
        // This will ensure that the sql objects are closed when the program 
        // is finished with them
        try (Connection connection = DriverManager.getConnection( url, userid, password );
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery( sql ))
            ResultSetMetaData md = rs.getMetaData();
            int columns = md.getColumnCount();

            //  Get column names
            for (int i = 1; i <= columns; i++)
                columnNames.add( md.getColumnName(i) );

            //  Get row data
            while (
                ArrayList row = new ArrayList(columns);

                for (int i = 1; i <= columns; i++)
                    row.add( rs.getObject(i) );

                data.add( row );
        catch (SQLException e)
            System.out.println( e.getMessage() );

        // Create Vectors and copy over elements from ArrayLists to them
        // Vector is deprecated but I am using them in this example to keep 
        // things simple - the best practice would be to create a custom defined
        // class which inherits from the AbstractTableModel class
        Vector columnNamesVector = new Vector();
        Vector dataVector = new Vector();

        for (int i = 0; i < data.size(); i++)
            ArrayList subArray = (ArrayList)data.get(i);
            Vector subVector = new Vector();
            for (int j = 0; j < subArray.size(); j++)

        for (int i = 0; i < columnNames.size(); i++ )

        //  Create table with database data    
        JTable table = new JTable(dataVector, columnNamesVector)
            public Class getColumnClass(int column)
                for (int row = 0; row < getRowCount(); row++)
                    Object o = getValueAt(row, column);

                    if (o != null)
                        return o.getClass();

                return Object.class;

        JScrollPane scrollPane = new JScrollPane( table );
        getContentPane().add( scrollPane );

        JPanel buttonPanel = new JPanel();
        getContentPane().add( buttonPanel, BorderLayout.SOUTH );

    public static void main(String[] args)
        TableFromMySqlDatabase frame = new TableFromMySqlDatabase();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );

In the NetBeans IDE which you are using - you will need to add the MySQL JDBC Driver in Project Properties as I display here:

enter image description here

Otherwise the code will throw an SQLException stating that the driver cannot be found.

Now in my example, yourdb is the name of the database and animals is the name of the table that I am performing a query against.

Here is what will be output:

enter image description here

Parting note:

You stated that you were a novice and needed some help understanding some of the basic classes and concepts of Java. I will list a few here, but remember you can always browse the docs on Oracle's site.

Group dataframe and get sum AND count?

try this:

In [110]: (df.groupby('Company Name')
   .....:    .agg({'Organisation Name':'count', 'Amount': 'sum'})
   .....:    .reset_index()
   .....:    .rename(columns={'Organisation Name':'Organisation Count'})
   .....: )
          Company Name   Amount  Organisation Count
0  Vifor Pharma UK Ltd  4207.93                   5

or if you don't want to reset index:

df.groupby('Company Name')['Amount'].agg(['sum','count'])


df.groupby('Company Name').agg({'Amount': ['sum','count']})


In [98]: df.groupby('Company Name')['Amount'].agg(['sum','count'])
                         sum  count
Company Name
Vifor Pharma UK Ltd  4207.93      5

In [99]: df.groupby('Company Name').agg({'Amount': ['sum','count']})
                         sum count
Company Name
Vifor Pharma UK Ltd  4207.93     5

What is the regex pattern for datetime (2008-09-01 12:35:45 )?


C#: easiest way to populate a ListBox from a List

Try :

List<string> MyList = new List<string>();

listBox1.DataSource = MyList;

Have a look at ListControl.DataSource Property

DynamoDB vs MongoDB NoSQL

With 500k documents, there is no reason to scale whatsoever. A typical laptop with an SSD and 8GB of ram can easily do 10s of millions of records, so if you are trying to pick because of scaling your choice doesn't really matter. I would suggest you pick what you like the most, and perhaps where you can find the most online support with.

Open Source HTML to PDF Renderer with Full CSS Support

This command line tool is the business!

It uses webkit rendering engine(used in safari and KDE), I tested it on some complex sites and it was by far better than any other tool.

Using Linq to group a list of objects into a new grouped list of list of objects

var groupedCustomerList = userList
    .GroupBy(u => u.GroupID)
    .Select(grp => grp.ToList())

BLOB to String, SQL Server

          l_data long;
         select XXXXXX into l_data from XXXXX where rowid = p_rowid;
         return substr( l_data, 1, 4000);
  end getlabrapor1;

Count the number of commits on a Git branch

One way to do it is list the log for your branch and count the lines.

git log <branch_name> --oneline | wc -l

Importing lodash into angular2 + typescript application

Since Typescript 2.0, @types npm modules are used to import typings.

# Implementation package (required to run)
$ npm install --save lodash

# Typescript Description
$ npm install --save @types/lodash 

Now since this question has been answered I'll go into how to efficiently import lodash

The failsafe way to import the entire library (in main.ts)

import 'lodash';

This is the new bit here:

Implementing a lighter lodash with the functions you require

import chain from "lodash/chain";
import value from "lodash/value";
import map from "lodash/map";
import mixin from "lodash/mixin";
import _ from "lodash/wrapperLodash";


PS: The above article is an interesting read on improving build time and reducing app size

Two models in one view in ASP MVC 3

I hope you find it helpfull !!

i use ViewBag For Project and Model for task so in this way i am using two model in single view and in controller i defined viewbag's value or data

List<tblproject> Plist = new List<tblproject>();_x000D_
            Plist = ps.getmanagerproject(c, id);_x000D_
            ViewBag.projectList = Plist.Select(x => new SelectListItem_x000D_
                Value = x.ProjectId.ToString(),_x000D_
                Text = x.Title_x000D_

and in view tbltask and projectlist are my two diff models


IEnumerable<SelectListItem> plist = ViewBag.projectList;

} @model List

Jackson with JSON: Unrecognized field, not marked as ignorable

You can use

ObjectMapper objectMapper = getObjectMapper();
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

It will ignore all the properties that are not declared.

Pass arguments to Constructor in VBA

Another approach

Say you create a class clsBitcoinPublicKey

In the class module create an ADDITIONAL subroutine, that acts as you would want the real constructor to behave. Below I have named it ConstructorAdjunct.

Public Sub ConstructorAdjunct(ByVal ...)


End Sub

From the calling module, you use an additional statement

Dim loPublicKey AS clsBitcoinPublicKey

Set loPublicKey = New clsBitcoinPublicKey

Call loPublicKey.ConstructorAdjunct(...)

The only penalty is the extra call, but the advantage is that you can keep everything in the class module, and debugging becomes easier.

How to get overall CPU usage (e.g. 57%) on Linux

Take a look at cat /proc/stat

grep 'cpu ' /proc/stat | awk '{usage=($2+$4)*100/($2+$4+$5)} END {print usage "%"}'

EDIT please read comments before copy-paste this or using this for any serious work. This was not tested nor used, it's an idea for people who do not want to install a utility or for something that works in any distribution. Some people think you can "apt-get install" anything.

NOTE: this is not the current CPU usage, but the overall CPU usage in all the cores since the system bootup. This could be very different from the current CPU usage. To get the current value top (or similar tool) must be used.

Current CPU usage can be potentially calculated with:

awk '{u=$2+$4; t=$2+$4+$5; if (NR==1){u1=u; t1=t;} else print ($2+$4-u1) * 100 / (t-t1) "%"; }' \
<(grep 'cpu ' /proc/stat) <(sleep 1;grep 'cpu ' /proc/stat)

Java Thread Example?

There is no guarantee that your threads are executing simultaneously regardless of any trivial example anyone else posts. If your OS only gives the java process one processor to work on, your java threads will still be scheduled for each time slice in a round robin fashion. Meaning, no two will ever be executing simultaneously, but the work they do will be interleaved. You can use monitoring tools like Java's Visual VM (standard in the JDK) to observe the threads executing in a Java process.

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

I think "disabled" excludes the input from being sent on the POST

Min/Max-value validators in mvc

Here is how I would write a validator for MaxValue

public class MaxValueAttribute : ValidationAttribute
        private readonly int _maxValue;

        public MaxValueAttribute(int maxValue)
            _maxValue = maxValue;

        public override bool IsValid(object value)
            return (int) value <= _maxValue;

The MinValue Attribute should be fairly the same

Correct way to initialize empty slice

Empty slice and nil slice are initialized differently in Go:

var nilSlice []int 
emptySlice1 := make([]int, 0)
emptySlice2 := []int{}

fmt.Println(nilSlice == nil)    // true
fmt.Println(emptySlice1 == nil) // false
fmt.Println(emptySlice2 == nil) // false

As for all three slices, len and cap are 0.

How to sort a Collection<T>?

Collections by themselves do not have a predefined order, therefore you must convert them to a java.util.List. Then you can use one form of java.util.Collections.sort

Collection< T > collection = ...;

List< T > list = new ArrayList< T >( collection );

Collections.sort( list );
 // or
Collections.sort( list, new Comparator< T >( ){...} );

// list now is sorted

How to extract URL parameters from a URL with Ruby or Rails?

I found myself needing the same thing for a recent project. Building on Levi's solution, here's a cleaner and faster method:

Rack::Utils.parse_nested_query 'param1=value1&param2=value2&param3=value3'
# => {"param1"=>"value1", "param2"=>"value2", "param3"=>"value3"}

Selected tab's color in Bottom Navigation View

It's too late to answer but might be helpful for someone. I was doing a very silly mistake, I was using a selector file named as bottom_color_nav.xml for Select and unselect color change but still it was not reflecting any color change in BottomNavigationView.

Then I realize, I was returning false in onNavigationItemSelected method. It will work fine if you'll return true in this method.

How to solve WAMP and Skype conflict on Windows 7?

Run Wamp services before Skype
Quit Skype >>> Run WAMP >>> Run Skype

When is each sorting algorithm used?

@dsimcha wrote: Counting sort: When you are sorting integers with a limited range

I would change that to:

Counting sort: When you sort positive integers (0 - Integer.MAX_VALUE-2 due to the pigeonhole).

You can always get the max and min values as an efficiency heuristic in linear time as well.
Also you need at least n extra space for the intermediate array and it is stable obviously.

* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

(even though it actually will allow to MAX_VALUE-2) see: Do Java arrays have a maximum size?

Also I would explain that radix sort complexity is O(wn) for n keys which are integers of word size w. Sometimes w is presented as a constant, which would make radix sort better (for sufficiently large n) than the best comparison-based sorting algorithms, which all perform O(n log n) comparisons to sort n keys. However, in general w cannot be considered a constant: if all n keys are distinct, then w has to be at least log n for a random-access machine to be able to store them in memory, which gives at best a time complexity O(n log n). (from wikipedia)

Java multiline string

JEP 378: Text Blocks covers this functionality and is included in JDK 15. It first appeared as JEP 355: Text Blocks (Preview) in JDK 13 and JEP 368: Text Blocks (Second Preview) in JDK 14 and can be enabled in these versions with the ––enable–preview javac option.

The syntax allows to write something like:

String s = """

Previous to this JEP, in JDK 12, JEP 326: Raw String Literals aimed to implement a similar feature, but it was eventually withdrawn:

Please note: This was intended to be a preview language feature in JDK 12, but it was withdrawn and did not appear in JDK 12. It was superseded by Text Blocks (JEP 355) in JDK 13.

Excel - extracting data based on another list

I have been hasseling with that as other folks have.

I used the criteria;


where matchingList is the list that i am using as a filter.

have a look at this

The trick i found is that normally you would have the column heading in the criteria matching the data column heading. this will not work for criteria that is a formula.

What I found was if I left the column heading blank for only the criteria that has the countif formula in the advanced filter works. If I have the column heading i.e. the column heading for column C2 in my formula example then the filter return no output.

Hope this helps

How can one pull the (private) data of one's own Android app?

Backed up Game data with apk. Nougat Oneplus 2.

**adb backup "-apk com.nekki.shadowfight" -f "c:\myapk\samsung2.ab"**

Use sudo with password as parameter

You can set the s bit for your script so that it does not need sudo and runs as root (and you do not need to write your root password in the script):

sudo chmod +s myscript

Android Studio how to run gradle sync manually?

WARNING: --recompile-scripts command has been deprecated since gradle's version 5.0. To check your gradle version, run gradle -v.

./gradlew --recompile-scripts

it will do a sync without building anything.

Alternatively, with command line in your root project

./gradlew build

It will sync and build your app, and take longer than just a Gradle sync

To see all available gradle task, use ./gradlew tasks

Get loop counter/index using for…of syntax in JavaScript

That's my version of a composite iterator that yields an index and any passed generator function's value with an example of (slow) prime search:

const eachWithIndex = (iterable) => {_x000D_
  return {_x000D_
    *[Symbol.iterator]() {_x000D_
      let i = 0_x000D_
      for(let val of iteratable) {_x000D_
          yield [i, val]_x000D_
const isPrime = (n) => {_x000D_
  for (i = 2; i < Math.floor(Math.sqrt(n) + 1); i++) {_x000D_
    if (n % i == 0) {_x000D_
      return false_x000D_
  return true_x000D_
let primes = {_x000D_
  *[Symbol.iterator]() {_x000D_
    let candidate = 2_x000D_
    while (true) {_x000D_
      if (isPrime(candidate)) yield candidate_x000D_
for (const [i, prime] of eachWithIndex(primes)) {_x000D_
  console.log(i, prime)_x000D_
  if (i === 100) break_x000D_

Handling the null value from a resultset in JAVA

The String being null is a very good chance, but when you see values in your table, yet a null is printed by the ResultSet, it might mean that the connection was closed before the value of ResultSet was used.

con = DriverManager.getConnection("jdbc:sqlite:My_db.db");
String sql = ("select * from cust where cust_id='" + cus + "'");
pst = con.prepareStatement(sql);
rs = pst.executeQuery();

Would print null even if there are values.

con = DriverManager.getConnection("jdbc:sqlite:My_db.db");
String sql = ("select * from cust where cust_id='" + cus + "'");
pst = con.prepareStatement(sql);
rs = pst.executeQuery();

Wouldn't print null if there are values in the table.

How to get current user in core

Taking IdentityUser would also work. This is a current user object and all values of user can be retrieved.

private readonly UserManager<IdentityUser> _userManager;
public yourController(UserManager<IdentityUser> userManager)
    _userManager = userManager;

var user = await _userManager.GetUserAsync(HttpContext.User);

Running an Excel macro via Python?

A variation on SMNALLY's code that doesn't quit Excel if you already have it open:

import os, os.path
import win32com.client
if os.path.exists("excelsheet.xlsm"):
    wb = xl.Workbooks.Open(os.path.abspath("excelsheet.xlsm"), ReadOnly=1) #create a workbook object
    wb.Close(False) #close the work sheet object rather than quitting excel
    del wb
    del xl

Java: Casting Object to Array type

Your values object is obviously an Object[] containing a String[] containing the values.

String[] stringValues = (String[])values[0];

Check/Uncheck all the checkboxes in a table


Add onClick event to checkbox where you want, like below.

<input type="checkbox" onClick="selectall(this)"/>Select All<br/>
<input type="checkbox" name="foo" value="make">Make<br/>
<input type="checkbox" name="foo" value="model">Model<br/>
<input type="checkbox" name="foo" value="descr">Description<br/>
<input type="checkbox" name="foo" value="startYr">Start Year<br/>
<input type="checkbox" name="foo" value="endYr">End Year<br/>

In JavaScript you can write selectall function as

function selectall(source) {
  checkboxes = document.getElementsByName('foo');
  for(var i=0, n=checkboxes.length;i<n;i++) {
    checkboxes[i].checked = source.checked;

ORA-01008: not all variables bound. They are bound

Came here looking for help as got same error running a statement listed below while going through a Udemy course:

INSERT INTO departments (department_id, department_name)
                  values( &dpet_id, '&dname');  

I'd been able to run statements with substitution variables before. Comment by Charles Burns about possibility of server reaching some threshold while recreating the variables prompted me to log out and restart the SQL Developer. The statement ran fine after logging back in.

Thought I'd share for anyone else venturing here with a limited scope issue as mine.

Running a Python script from PHP

This is so trivial, but just wanted to help anyone who already followed along Alejandro's suggestion but encountered this error:

sh: command not found

If anyone encountered that error, then a little change needs to be made to the php file by Alejandro:

$command = escapeshellcmd('python');

Eclipse JPA Project Change Event Handler (waiting)

The issue seems to be resolved with the new Eclipse. The plugin isn't available with Java Enterprise suite.

How to read data From *.CSV file using javascript?

NOTE: I concocted this solution before I was reminded about all the "special cases" that can occur in a valid CSV file, like escaped quotes. I'm leaving my answer for those who want something quick and dirty, but I recommend Evan's answer for accuracy.

This code will work when your data.txt file is one long string of comma-separated entries, with no newlines:




$(document).ready(function() {
        type: "GET",
        url: "data.txt",
        dataType: "text",
        success: function(data) {processData(data);}

function processData(allText) {
    var record_num = 5;  // or however many elements there are in each row
    var allTextLines = allText.split(/\r\n|\n/);
    var entries = allTextLines[0].split(',');
    var lines = [];

    var headings = entries.splice(0,record_num);
    while (entries.length>0) {
        var tarr = [];
        for (var j=0; j<record_num; j++) {
    // alert(lines);

The following code will work on a "true" CSV file with linebreaks between each set of records:




$(document).ready(function() {
        type: "GET",
        url: "data.txt",
        dataType: "text",
        success: function(data) {processData(data);}

function processData(allText) {
    var allTextLines = allText.split(/\r\n|\n/);
    var headers = allTextLines[0].split(',');
    var lines = [];

    for (var i=1; i<allTextLines.length; i++) {
        var data = allTextLines[i].split(',');
        if (data.length == headers.length) {

            var tarr = [];
            for (var j=0; j<headers.length; j++) {
    // alert(lines);

Get all Attributes from a HTML element with Javascript/jQuery

Element.prototype.getA = function (a) {
        if (a) {
            return this.getAttribute(a);
        } else {
            var o = {};
            for(let a of this.attributes){
            return o;

having <div id="mydiv" a='1' b='2'>...</div> can use

mydiv.getA() // {id:"mydiv",a:'1',b:'2'}

Is it possible to force Excel recognize UTF-8 CSV files automatically?

Had the same problems with PHP-generated CSV files. Excel ignored the BOM when the Separator was defined via "sep=,\n" at the beginning of the content (but of course after the BOM).

So adding a BOM ("\xEF\xBB\xBF") at the beginning of the content and setting the semicolon as separator via fputcsv($fh, $data_array, ";"); does the trick.

Disable webkit's spin buttons on input type="number"?

I discovered that there is a second portion of the answer to this.

The first portion helped me, but I still had a space to the right of my type=number input. I had zeroed out the margin on the input, but apparently I had to zero out the margin on the spinner as well.

This fixed it:

input[type=number]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;

HTML5 Email input pattern attribute

I have tested the following regex which gives the same result as Chrome Html email input validation.


You can test it out on this website: regex101

What is Dispatcher Servlet in Spring?

The job of the DispatcherServlet is to take an incoming URI and find the right combination of handlers (generally methods on Controller classes) and views (generally JSPs) that combine to form the page or resource that's supposed to be found at that location.

I might have

  • a file /WEB-INF/jsp/pages/Home.jsp
  • and a method on a class

    private ModelMap buildHome() {
        return somestuff;

The Dispatcher servlet is the bit that "knows" to call that method when a browser requests the page, and to combine its results with the matching JSP file to make an html document.

How it accomplishes this varies widely with configuration and Spring version.

There's also no reason the end result has to be web pages. It can do the same thing to locate RMI end points, handle SOAP requests, anything that can come into a servlet.

List files in local git repo?

Try this command:

git ls-files 

This lists all of the files in the repository, including those that are only staged but not yet committed.

An attempt was made to access a socket in a way forbidden by its access permissions

I had a similar issue with Docker for Windows and Hyper-V having reserved ports for its own use- in my case, it was port 3001 that couldn't be accessed.

  • The port wasn't be used by another process- running netstat -ano | findstr 3001 in an Administrator Powershell prompt showed nothing.
  • However, netsh interface ipv4 show excludedportrange protocol=tcp showed that the port was in one of the exclusion ranges.

I was able to follow the solution described in Docker for Windows issue #3171 (Unable to bind ports: Docker-for-Windows & Hyper-V excluding but not using important port ranges):

  1. Disable Hyper-V:

    dism.exe /Online /Disable-Feature:Microsoft-Hyper-V
  2. After the required restarts, reserve the port you want so Hyper-V doesn't reserve it back:

    netsh int ipv4 add excludedportrange protocol=tcp startport=3001 numberofports=1
  3. Reenable Hyper-V:

    dism.exe /Online /Enable-Feature:Microsoft-Hyper-V /All

After this, I was able to start my docker container.

Django 1.7 - makemigrations not detecting changes

Maybe this will help someone. I was using a nested app. project.appname and I actually had project and project.appname in INSTALLED_APPS. Removing project from INSTALLED_APPS allowed the changes to be detected.

How to import Maven dependency in Android Studio/IntelliJ?

Try itext. Add dependency to your build.gradle for latest as of this post

Note: special version for android, trailing "g":

dependencies {
    compile 'com.itextpdf:itextg:5.5.9'

jQuery: If this HREF contains

Try this:

$("a").each(function() {
    if ($('[href$="?"]', this).length()) {
        alert("Contains questionmark");

enum Values to NSString (iOS)

I will introduce is the way I use, and it looks better than previous answer.(I thinks)

I would like to illustrate with UIImageOrientation for easy understanding.

typedef enum {
    UIImageOrientationUp = 0,            // default orientation, set to 0 so that it always starts from 0
    UIImageOrientationDown,          // 180 deg rotation
    UIImageOrientationLeft,          // 90 deg CCW
    UIImageOrientationRight,         // 90 deg CW
    UIImageOrientationUpMirrored,    // as above but image mirrored along other axis. horizontal flip
    UIImageOrientationDownMirrored,  // horizontal flip
    UIImageOrientationLeftMirrored,  // vertical flip
    UIImageOrientationRightMirrored, // vertical flip
} UIImageOrientation;

create a method like:

NSString *stringWithUIImageOrientation(UIImageOrientation input) {
    NSArray *arr = @[
    @"UIImageOrientationUp",            // default orientation
    @"UIImageOrientationDown",          // 180 deg rotation
    @"UIImageOrientationLeft",          // 90 deg CCW
    @"UIImageOrientationRight",         // 90 deg CW
    @"UIImageOrientationUpMirrored",    // as above but image mirrored along other axis. horizontal flip
    @"UIImageOrientationDownMirrored",  // horizontal flip
    @"UIImageOrientationLeftMirrored",  // vertical flip
    @"UIImageOrientationRightMirrored", // vertical flip
    return (NSString *)[arr objectAtIndex:input];

All you have to do is :

  1. name your function.

  2. copy contents of enum and paste that between NSArray *arr = @[ and ]; return (NSString *)[arr objectAtIndex:input];

  3. put some @ , " , and comma

  4. PROFIT!!!!

How to play an android notification sound

If anyone's still looking for a solution to this, I found an answer at How to play ringtone/alarm sound in Android

try {
    Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);;
} catch (Exception e) {

You can change TYPE_NOTIFICATION to TYPE_ALARM, but you'll want to keep track of your Ringtone r in order to stop playing it... say, when the user clicks a button or something.

Bootstrap Collapse not Collapsing

Add jQuery and make sure only one link for jQuery cause more than one doesn't work...

Console app arguments, how arguments are passed to Main method

How is main called?

When you are using the console application template the code will be compiled requiring a method called Main in the startup object as Main is market as entry point to the application.

By default no startup object is specified in the project propery settings and the Program class will be used by default. You can change this in the project property under the "Build" tab if you wish.

Keep in mind that which ever object you assign to be the startup object must have a method named Main in it.

How are args passed to main method

The accepted format is MyConsoleApp.exe value01 value02 etc...

The application assigns each value after each space into a separate element of the parameter array.

Thus, MyConsoleApp.exe value01 value02 will mean your args paramter has 2 elements:

[0] = "value01"

[1] = "value02"

How you parse the input values and use them is up to you.

Hope this helped.

Additional Reading:

Creating Console Applications (Visual C#)

Command-Line Arguments (C# Programming Guide)

How do you set the document title in React?

Simply you can create a function in a js file and export it for usages in components

like below:

export default function setTitle(title) {
  if (typeof title !== "string") {
     throw new Error("Title should be an string");
  document.title = title;

and use it in any component like this:

import React, { Component } from 'react';
import setTitle from './setTitle.js' // no need to js extension at the end

class App extends Component {
  componentDidMount() {
    setTitle("i am a new title");

  render() {
    return (
        see the title

export default App

How to get CRON to call in the correct PATHs

You should put full paths in your crontab. That's the safest option.
If you don't want to do that you can put a wrapper script around your programs, and set the PATH in there.


01 01 * * * command


01 01 * * * /full/path/to/command

Also anything called from cron should be be very careful about the programs it runs, and probably set its own choice for the PATH variable.


If you don't know where the command is that you want execute which <command> from your shell and it'll tell you the path.


So once your program is running, the first thing it should do is set PATH and any other required variable (e.g. LD_LIBRARY_PATH) to the values that are required for the script to run.
Basically instead of thinking how to modify the cron environment to make it more suitable for your program/script - make your script handle the environment it's given, by setting an appropriate one when it starts.

XAMPP Apache Webserver localhost not working on MAC OS

In my case, Web Sharing was running, which blocked XAMPP.

'Untick' Web Sharing in the Bluetooth Settings (or Network), which causes HTTPD to show in activity log.

Apache should now run and be available!

How to get date in BAT file

Locale-independent one liner to get any date format you like. I use it to generate archive names. Back quote option is needed because PowerShell command line is using single quotes.

:: Get date in yyyyMMdd_HHmm format to use with file name.
FOR /f "usebackq" %%i IN (`PowerShell ^(Get-Date^).ToString^('yyyy-MM-dd'^)`) DO SET DTime=%%i

:: Get formatted yesterday date.
FOR /f "usebackq" %%i IN (`PowerShell ^(Get-Date^).AddDays^(-1^).ToString^('yyyy-MM-dd'^)`) DO SET DTime=%%i

:: Show file name with the date.

Execute PowerShell Script from C# with Commandline Arguments

You can also just use the pipeline with the AddScript Method:

string cmdArg = ".\script.ps1 -foo bar"            
Collection<PSObject> psresults;
using (Pipeline pipeline = _runspace.CreatePipeline())
                pipeline.Commands[0].MergeMyResults(PipelineResultTypes.Error, PipelineResultTypes.Output);
                psresults = pipeline.Invoke();
return psresults;

It will take a string, and whatever parameters you pass it.

How do I add options to a DropDownList using jQuery?

using jquery you can use


where "myid" is the id of the dropdown list and newvalue is the text that you want to insert..

How can I convert a stack trace to a string?

Old question, but I would just like to add the special case where you don't want to print all the stack, by removing some parts you are not actually interested in, excluding certain classes or packages.

Instead of a PrintWriter use a SelectivePrintWriter:

// This filters out this package and up.
String packageNameToFilter = "org.springframework";

StringWriter sw = new StringWriter();
PrintWriter pw = new SelectivePrintWriter(sw, packageNameToFilter);
String sStackTrace = sw.toString(); 

Where the SelectivePrintWriter class is given by:

public class SelectivePrintWriter extends PrintWriter {
    private boolean on = true;
    private static final String AT = "\tat";
    private String internal;

    public SelectivePrintWriter(Writer out, String packageOrClassName) {
        internal = "\tat " + packageOrClassName;

    public void println(Object obj) {
        if (obj instanceof String) {
            String txt = (String) obj;
            if (!txt.startsWith(AT)) on = true;
            else if (txt.startsWith(internal)) on = false;
            if (on) super.println(txt);
        } else {

Please note this class may be easily adapted to filter out by Regex, contains or other criteria. Also note it depends upon Throwable implementation details (not likely to change, but still).

Access Google's Traffic Data through a Web Service

I don't think Google will provide this API. And traffic data not only contains the incident data.

Today many online maps show city traffic, but they have not provide the API for the developer. We even don't know where they get the traffic data. Maybe the government has the data.

So I think you could think about it from another direction. For example, there are many social network website out there. Everybody could post the traffic information on the website. We can collection these information to get the traffic status. Or maybe we can create a this type website.

But that type traffic data (talked about above) is not accurate. Even the information provided by human will be wrong.

Luckily I found that my city now provides an Mobile App called "Real-time Bus Information". It could tell the citizen where the bus is now, and when will arrive at the bus station. And I sniff the REST API in this App. The data from REST API give the important data, for example the lat and lon, and also the bus speed. And it's real-time data! So I think we could compute the traffic status from these data (by some programming). Here is some sample data :

Even the bus data will not enough to compute the accurate real-time traffic status. Incidents, traffic light and other things will affect the traffic status. But I think this is the beginning.

At the end, I think you could try to find whether your city provides these data.

PS: I am always thinking that life will be better for people in the future , but not now.

For Loop on Lua

names = {'John', 'Joe', 'Steve'}
for names = 1, 3 do
  print (names)
  1. You're deleting your table and replacing it with an int
  2. You aren't pulling a value from the table


names = {'John','Joe','Steve'}
for i = 1,3 do

How do I inject a controller into another controller in AngularJS

The best solution:-

    $"Atul Singh";
     angular.extend(this, $controller('frstCtrl', {$scope:$scope}));

// Here you got the first controller call without executing it

Where does VBA Debug.Print log to?

Where do you want to see the output?

Messages being output via Debug.Print will be displayed in the immediate window which you can open by pressing Ctrl+G.

You can also Activate the so called Immediate Window by clicking View -> Immediate Window on the VBE toolbar

enter image description here

TypeError: 'list' object is not callable in python

Why does TypeError: 'list' object is not callable appear?


It is because you defined list as a variable before (i am pretty sure), so it would be a list, not the function anymore, that's why everyone shouldn't name variables functions, the below is the same as what you're doing now:

>>> [1,2,3]()
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
TypeError: 'list' object is not callable

So you need it to be the default function of list, how to detect if it is? just use:

>>> list
<class 'list'>
>>> list = [1,2,3]
>>> list
[1, 2, 3]
>>> list()
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
TypeError: 'list' object is not callable

How do i detect whether a variable name is a function? well, just simple see if it has a different color, or use a code like:

>>> 'list' in dir(__builtins__)
>>> 'blah' in dir(__builtins__)

After this, you should know why does TypeError: 'list' object is not callable appear.

Okay, so now...

How to fix this TypeError: 'list' object is not callable error?


You have to either do __builtins__.list():

>>> list = [1,2,3]
>>> __builtins__.list()

Or use []:

>>> list = [1,2,3]
>>> []

Or remove list variable from memory:

>>> list = [1,2,3]
>>> del list
>>> list()

Or just rename the variable:

>>> lst = [1,2,3]
>>> list()

P.S. Last one is the most preferable i guess :-)

There are a whole bunch of solutions that work.


'id' is a bad variable name in Python

How do I use a keyword as a variable name?

How to use reserved keyword as the name of variable in python?

C++ String Declaring

using the standard <string> header

std::string Something = "Some Text";

Creating a comma separated list from IList<string> or IEnumerable<string>

I wrote a few extension methods to do it in a way that's efficient:

    public static string JoinWithDelimiter(this IEnumerable<String> that, string delim) {
        var sb = new StringBuilder();
        foreach (var s in that) {

        return sb.ToString();

This depends on

    public static string AppendToList(this String s, string item, string delim) {
        if (s.Length == 0) {
            return item;

        return s+delim+item;

How do I create a folder in VB if it doesn't exist?

Try this: Directory.Exists(TheFolderName) and Directory.CreateDirectory(TheFolderName)

(You may need: Imports System.IO)