Programs & Examples On #Wifi

GENERAL WIFI SUPPORT IS OFF-TOPIC. Questions about hardware support should be directed to This tag should be used for questions about writing software that directly interacts with Wi-Fi devices. failed to connect to / (port 2468): connect failed: ECONNREFUSED (Connection refused)

My problem was solved after turning Off Windows Firewall Defender in public network as I was connected with that network.

How to connect android wifi to adhoc wifi?

You are correct that this is currently not natively supported in Android, although Google has been saying it will be coming ever since Android was officially launched.

While not natively supported, the hardware on every android device released to date do support it. It is just disabled in software, and you would need to enable it in order to use these features.

It is however, fairly easy to do this, but you need to be root, and the specifics may be slightly different between different devices. Your best source for more informationa about this, would be XDA developers: Most of the existing solutions are based on replacing wpa_supplicant, and is the method I would recommend if possible on your device. For more details, see

Update: Its been a few years now, and whenever I need an ad hoc network connection on my phone I use CyanogenMod. It gives you both programmatic and scripted access to these functions, and the ability to create ad hoc (ibss) networks in the WiFi settings menu.

Android turn On/Off WiFi HotSpot programmatically

You can use the console and service for that option.

I think with this you can solve that. I made a test directly in console and enable hotspot

I found this in this article Is it possible to USB tether an android device using adb through the terminal?

And after read the interface we can use the same 24 but needs more parameters

service call connectivity 24 i32 0 i32 1 i32 0 s16 random

Enabling/Disabling Microsoft Virtual WiFi Miniport

In the device manager you can select View > Show hidden devices

Detect network connection type on Android

You can try this:

public String ConnectionQuality() {
    NetworkInfo info = getInfo(context);
    if (info == null || !info.isConnected()) {
      return "UNKNOWN";

    if(info.getType() == ConnectivityManager.TYPE_WIFI) {
        WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
        int numberOfLevels = 5;
        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
        int level = WifiManager.calculateSignalLevel(wifiInfo.getRssi(), numberOfLevels);
        if(level == 2 )
                return "POOR";
            else if(level == 3 )
                return "MODERATE";
            else if(level == 4 )
                return "GOOD";
            else if(level == 5 )
                return "EXCELLENT";
            return "UNKNOWN";
        }else if(info.getType() == ConnectivityManager.TYPE_MOBILE) {
            int networkClass = getNetworkClass(getNetworkType(context));
            if(networkClass == 1)
                return "POOR";
            else if(networkClass == 2 )
                return "GOOD";
            else if(networkClass == 3 )
                return "EXCELLENT";
                return "UNKNOWN";
            return "UNKNOWN";  

public NetworkInfo getInfo(Context context) {
    return ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo();

public int getNetworkClass(int networkType) {
    try {
      return getNetworkClassReflect(networkType);
    }catch (Exception ignored) {

    switch (networkType) {
      case TelephonyManager.NETWORK_TYPE_GPRS:
      case 16: // TelephonyManager.NETWORK_TYPE_GSM:
      case TelephonyManager.NETWORK_TYPE_EDGE:
      case TelephonyManager.NETWORK_TYPE_CDMA:
      case TelephonyManager.NETWORK_TYPE_1xRTT:
      case TelephonyManager.NETWORK_TYPE_IDEN:
        return 1;
      case TelephonyManager.NETWORK_TYPE_UMTS:
      case TelephonyManager.NETWORK_TYPE_EVDO_0:
      case TelephonyManager.NETWORK_TYPE_EVDO_A:
      case TelephonyManager.NETWORK_TYPE_HSDPA:
      case TelephonyManager.NETWORK_TYPE_HSUPA:
      case TelephonyManager.NETWORK_TYPE_HSPA:
      case TelephonyManager.NETWORK_TYPE_EVDO_B:
      case TelephonyManager.NETWORK_TYPE_EHRPD:
      case TelephonyManager.NETWORK_TYPE_HSPAP:
      case 17: // TelephonyManager.NETWORK_TYPE_TD_SCDMA:
        return 2;
      case TelephonyManager.NETWORK_TYPE_LTE:
      case 18: // TelephonyManager.NETWORK_TYPE_IWLAN:
        return 3;
        return 0;

private int getNetworkClassReflect(int networkType) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {  
    Method getNetworkClass = TelephonyManager.class.getDeclaredMethod("getNetworkClass", int.class);
    if (!getNetworkClass.isAccessible()) {
    return (Integer) getNetworkClass.invoke(null, networkType); 

public static int getNetworkType(Context context) {
    return ((TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE)).getNetworkType();

Run/install/debug Android applications over Wi-Fi?

See forum post Any way to view Android screen remotely without root? - Post #9.

  1. Connect the device via USB and make sure debugging is working;
  2. adb tcpip 5555. This makes the device to start listening for connections on port 5555;
  3. Look up the device IP address with adb shell netcfg or adb shell ifconfig with 6.0 and higher;
  4. You can disconnect the USB now;
  5. adb connect <DEVICE_IP_ADDRESS>:5555. This connects to the server we set up on the device on step 2;
  6. Now you have a device over the network with which you can debug as usual.

To switch the server back to the USB mode, run adb usb, which will put the server on your phone back to the USB mode. If you have more than one device, you can specify the device with the -s option: adb -s <DEVICE_IP_ADDRESS>:5555 usb.

No root required!

To find the IP address of the device: run adb shell and then netcfg. You'll see it there. To find the IP address while using OSX run the command adb shell ip route.

WARNING: leaving the option enabled is dangerous, anyone in your network can connect to your device in debug, even if you are in data network. Do it only when connected to a trusted Wi-Fi and remember to disconnect it when done!

@Sergei suggested that line 2 should be modified, commenting: "-d option needed to connect to the USB device when the other connection persists (for example, emulator connected or other Wi-Fi device)".

This information may prove valuable to future readers, but I rolled-back to the original version that had received 178 upvotes.

On some device you can do the same thing even if you do not have an USB cable:

  1. Enable ADB over network in developer setting Screenshot Showing the option on It should show the IP address
  2. adb connect <DEVICE_IP_ADDRESS>:5555
  3. Disable the setting when done

Using Android Studio there is a plugin allowing you to connect USB Debugging without the need of using any ADB command from a terminal.

Get SSID when WIFI is connected

Starting with Android 8.1 (API 27), apps must be granted the ACCESS_COARSE_LOCATION (or ACCESS_FINE_LOCATION) permission in order to obtain results from WifiInfo.getSSID() or WifiInfo.getBSSID(). Apps that target API 29 or higher (Android 10) must be granted ACCESS_FINE_LOCATION.

This permission is also needed to obtain results from WifiManager.getConnectionInfo() and WifiManager.getScanResults() although it is not clear if this is new in 8.1 or was required previously.

Source: "BSSID/SSID can be used to deduce location, so require the same location permissions for access to these WifiInfo fields requested using WifiManager.getConnectionInfo() as for WifiManager.getScanResults()."

Connect Android to WiFi Enterprise network EAP(PEAP)

Thanks for enlightening us Cypawer.

I also tried this app

and it worked flawlessly.

Leap Wifi Connector

" netsh wlan start hostednetwork " command not working no matter what I try

First of all go to the device manager now go to View>>select Show hidden devices....Then go to network adapters and find out Microsoft Hosted network Virual Adapter ....Press right click and enable the option....

Then go to command prompt with administrative privileges and enter the following commands:

netsh wlan set hostednetwork mode=allow
netsh wlan start hostednetwork

Your Hostednetwork will work without any problems.

Enabling WiFi on Android Emulator

When using an AVD with API level 25 or higher, the emulator provides a simulated Wi-Fi access point ("AndroidWifi"), and Android automatically connects to it.

Source :

Can Android do peer-to-peer ad-hoc networking?

Although Android can't find and connect to ad-hoc networks it sure can connect to Access Points. So as a work-around you can turn your Wireless Card into an Access Point using, for example, Connectify.

How to calculate distance from Wifi router using Signal Strength?

To calculate the distance you need signal strength and frequency of the signal. Here is the java code:

public double calculateDistance(double signalLevelInDb, double freqInMHz) {
    double exp = (27.55 - (20 * Math.log10(freqInMHz)) + Math.abs(signalLevelInDb)) / 20.0;
    return Math.pow(10.0, exp);

The formula used is:

distance = 10 ^ ((27.55 - (20 * log10(frequency)) + signalLevel)/20)

Example: frequency = 2412MHz, signalLevel = -57dbm, result = 7.000397427391188m

This formula is transformed form of Free Space Path Loss(FSPL) formula. Here the distance is measured in meters and the frequency - in megahertz. For other measures you have to use different constant (27.55). Read for the constants here.

For more information read here.

use "netsh wlan set hostednetwork ..." to create a wifi hotspot and the authentication can't work correctly

Use these commands on a windows command prompt(cmd) with administrator privilege (run as administrator):

netsh wlan set hostednetwork mode=allow ssid=tests key=tests123

netsh wlan start hostednetwork

Then you go to Network and sharing center and click on "change adapter settings" (I'm using windows 7, it can be a little different on windows 8)

Then right click on the lan connection (internet connection that you are using), properties.

Click on sharing tab, select the wireless connection tests (the name tests you can change on the command line) and check "Allow other network users to connect through this network connection"

This done, your connection is ready to use!

Connect Device to Mac localhost Server?

Try enabling Internet Sharing:
Open System Preferences -> Sharing. Check Internet Sharing to turn it on, it will prompt you to confirm your action, select ok. If your iPhone is connected using USB, the iPhone USB is checked at the "sharing your connection" list on the right side.
After this, try accessing your local server using your macs ip on wifi.

Android Studio-No Module

For some reason, I was missing the settings.gradle file.

  1. Create settings.gradle under your root directory, and inside it:
include ':app'

(assuming your app is indeed inside /app directory).

  1. Hit File -> Sync Project with Gradle Files.

After that everything worked out for me.

How can moment.js be imported with typescript?

You need to import moment() the function and Moment the class separately in TS.

I found a note in the typescript docs here.

/*~ Note that ES6 modules cannot directly export callable functions
*~ This file should be imported using the CommonJS-style:
*~ import x = require('someLibrary');

So the code to import moment js into typescript actually looks like this:

import { Moment } from 'moment'
let moment = require('moment');
interface SomeTime {
  aMoment: Moment,
fn() {
  someTime.aMoment = moment(...);

How to dump only specific tables from MySQL?

If you're in local machine then use this command

/usr/local/mysql/bin/mysqldump -h127.0.0.1 --port = 3306 -u [username] -p [password] --databases [db_name] --tables [tablename] > /to/path/tablename.sql;

For remote machine, use below one

/usr/local/mysql/bin/mysqldump -h [remoteip] --port = 3306 -u [username] -p [password] --databases [db_name] --tables [tablename] > /to/path/tablename.sql;

Is there a workaround for ORA-01795: maximum number of expressions in a list is 1000 error?

I realize this is an old question and referring to TOAD but if you need to code around this using c# you can split up the list through a for loop. You can essentially do the same with Java using subList();

    List<Address> allAddresses = GetAllAddresses();
    List<Employee> employees = GetAllEmployees(); // count > 1000

    List<Address> addresses = new List<Address>();

    for (int i = 0; i < employees.Count; i += 1000)
        int count = ((employees.Count - i) < 1000) ? (employees.Count - i) - 1 : 1000;
        var query = (from address in allAddresses
                     where employees.GetRange(i, count).Contains(address.EmployeeId)
                     && address.State == "UT"
                     select address).ToList();


Hope this helps someone.

Right align and left align text in same HTML table cell

Do you mean like this?

<!-- ... --->
   this text should be left justified
   and this text should be right justified?
<!-- ... --->

If yes

<!-- ... --->
   <p style="text-align: left;">this text should be left justified</p>
   <p style="text-align: right;">and this text should be right justified?</p>
<!-- ... --->

How do I explicitly specify a Model's table-name mapping in Rails?

class Countries < ActiveRecord::Base
    self.table_name = "cc"

In Rails 3.x this is the way to specify the table name.

Convert string to ASCII value python

It is not at all obvious why one would want to concatenate the (decimal) "ascii values". What is certain is that concatenating them without leading zeroes (or some other padding or a delimiter) is useless -- nothing can be reliably recovered from such an output.

>>> tests = ["hi", "Hi", "HI", '\x0A\x29\x00\x05']
>>> ["".join("%d" % ord(c) for c in s) for s in tests]
['104105', '72105', '7273', '104105']

Note that the first 3 outputs are of different length. Note that the fourth result is the same as the first.

>>> ["".join("%03d" % ord(c) for c in s) for s in tests]
['104105', '072105', '072073', '010041000005']
>>> [" ".join("%d" % ord(c) for c in s) for s in tests]
['104 105', '72 105', '72 73', '10 41 0 5']
>>> ["".join("%02x" % ord(c) for c in s) for s in tests]
['6869', '4869', '4849', '0a290005']

Note no such problems.

How to import a JSON file in ECMAScript 6?

In a browser with fetch (basically all of them now):

At the moment, we can't import files with a JSON mime type, only files with a JavaScript mime type. It might be a feature added in the future (official discussion).

  .then(response => response.json())
  .then(obj => console.log(obj))

In Node.js v13.2+:

It currently requires the --experimental-json-modules flag, otherwise it isn't supported by default.

Try running

node --input-type module --experimental-json-modules --eval "import obj from './file.json'; console.log(obj)"

and see the obj content outputted to console.

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

Splash screen sizes for Android

and at the same time for Cordova (a.k.a Phonegap), React-Native and all other development platforms

Format : 9-Patch PNG (recommended)


 - LDPI:
    - Portrait: 200x320px
    - Landscape: 320x200px
 - MDPI:
    - Portrait: 320x480px
    - Landscape: 480x320px
 - HDPI:
    - Portrait: 480x800px
    - Landscape: 800x480px
    - Portrait: 720px1280px
    - Landscape: 1280x720px
    - Portrait: 960x1600px
    - Landscape: 1600x960px
    - Portrait: 1280x1920px
    - Landscape: 1920x1280px

Note: Preparing XXXHDPI is not needed and also maybe XXHDPI size too because of the repeating areas of 9-patch images. On the other hand, if only Portrait sizes are used the App size could be more less. More pictures mean more space is need.

Pay attention

I think there is no an exact size for the all devices. I use Xperia Z 5". If you develop a crossplatform-webview app you should consider a lot of things (whether screen has softkey navigation buttons or not, etc). Therefore, I think there is only one suitable solution. The solution is to prepare a 9-patch splash screen (find How to design a new splash screen heading below).

  1. Create splash screens for the above screen sizes as 9-patch. Give names your files with .9.png suffixes
  2. Add the lines below into your config.xml file
  3. Add the splash screen plugin if it's needed.
  4. Run your project.

That's it!

Cordova specific code
To be added lines into the config.xml for 9-patch splash screens

<preference name="SplashScreen" value="screen" />
<preference name="SplashScreenDelay" value="6000" />
<platform name="android">
    <splash src="res/screen/android/ldpi.9.png" density="ldpi"/>
    <splash src="res/screen/android/mdpi.9.png" density="mdpi"/>
    <splash src="res/screen/android/hdpi.9.png" density="hdpi"/>
    <splash src="res/screen/android/xhdpi.9.png" density="xhdpi"/> 

To be added lines into the config.xml when using non-9-patch splash screens

<platform name="android">
    <splash src="res/screen/android/splash-land-hdpi.png" density="land-hdpi"/>
    <splash src="res/screen/android/splash-land-ldpi.png" density="land-ldpi"/>
    <splash src="res/screen/android/splash-land-mdpi.png" density="land-mdpi"/>
    <splash src="res/screen/android/splash-land-xhdpi.png" density="land-xhdpi"/>

    <splash src="res/screen/android/splash-port-hdpi.png" density="port-hdpi"/>
    <splash src="res/screen/android/splash-port-ldpi.png" density="port-ldpi"/>
    <splash src="res/screen/android/splash-port-mdpi.png" density="port-mdpi"/>
    <splash src="res/screen/android/splash-port-xhdpi.png" density="port-xhdpi"/>

How to design a new splash screen

I would describe a simple way to create proper splash screen using this way. Assume we're designing a 1280dp x 720dp - xhdpi (x-large) screen. I've written for the sake of example the below;

  • In Photoshop: File -> New in new dialog window set your screens

    Width: 720 Pixels Height: 1280 Pixels

    I guess the above sizes mean Resolution is 320 Pixels/Inch. But to ensure you can change resolution value to 320 in your dialog window. In this case Pixels/Inch = DPI

    Congratulations... You have a 720dp x 1280dp splash screen template.

How to generate a 9-patch splash screen

After you designed your splash screen, if you want to design 9-Patch splash screen, you should insert 1 pixel gap for every side. For this reason you should increase +2 pixel your canvas size's width and height ( now your image sizes are 722 x 1282 ).

I've left the blank 1 pixel gap at every side as directed the below.
Changing the canvas size by using Photoshop:
- Open a splash screen png file in Photoshop
- Click onto the lock icon next to the 'Background' name in the Layers field (to leave blank instead of another color like white) if there is like the below:
enter image description here
- Change the canvas size from Image menu ( Width: 720 pixels to 722 pixels and Height: 1280 pixels to 1282 pixels). Now, should see 1 pixel gap at every side of the splash screen image.

Then you can use C:\Program Files (x86)\Android\android-studio\sdk\tools\draw9patch.bat to convert a 9-patch file. For that open your splash screen on draw9patch app. You should define your logo and expandable areas. Notice the black line the following example splash screen. The black line's thickness is just 1 px ;) Left and Top sides black lines define your splash screen's must display area. Exactly as your designed. Right and Bottom lines define the addable and removable area (automatically repeating areas).

Just do that: Zoom your image's top edge on draw9patch application. Click and drag your mouse to draw line. And press shift + click and drag your mouse to erase line.

Sample 9-patch design

If you develop a cross-platform app (like Cordova/PhoneGap) you can find the following address almost all mabile OS splash screen sizes. Click for Windows Phone, WebOS, BlackBerry, Bada-WAC and Bada splash screen sizes.

And if you need IOS, Android etc. app icon sizes you can visit here.


Format : PNG (recommended)


 - Tablet (iPad)
   - Non-Retina (1x)
     - Portrait: 768x1024px
     - Landscape: 1024x768px
   - Retina (2x)
     - Portrait: 1536x2048px
     - Landscape: 2048x1536px
 - Handheld (iPhone, iPod)
   - Non-Retina (1x)
     - Portrait: 320x480px
     - Landscape: 480x320px
   - Retina (2x)
     - Portrait: 640x960px
     - Landscape: 960x640px
 - iPhone 5 Retina (2x)
   - Portrait: 640x1136px
   - Landscape: 1136x640px
 - iPhone 6 (2x)
   - Portrait: 750x1334px
   - Landscape: 1334x750px
 - iPhone 6 Plus (3x)
   - Portrait: 1242x2208px
   - Landscape: 2208x1242px

How to restore a SQL Server 2012 database to SQL Server 2008 R2?

Merge replication. You can create the subscriber (2008) from the distributor (2008). After the database has fully synchronized, drop the subscription and the publication.

Best practices for API versioning?

I agree that versioning the resource representation better follows the REST approach...but, one big problem with custom MIME types (or MIME types that append a version parameter) is the poor support to write to Accept and Content-Type headers in HTML and JavaScript.

For example, it is not possible IMO to POST with the following headers in HTML5 forms, in order to create a resource:

Accept: application/
Content-Type: application/ 

This is because the HTML5 enctype attribute is an enumeration, therefore anything other than the usual application/x-www-formurlencoded, multipart/form-data and text/plain are invalid.

...nor am I sure it is supported across all browsers in HTML4 (which has a more lax encytpe attribute, but would be a browser implementation issue as to whether the MIME type was forwarded)

Because of this I now feel the most appropriate way to version is via the URI, but I accept that it is not the 'correct' way.

When to use window.opener / window.parent /

when you are dealing with popups window.opener plays an important role, because we have to deal with fields of parent page as well as child page, when we have to use values on parent page we can use window.opener or we want some data on the child window or popup window at the time of loading then again we can set the values using window.opener

How do I add all new files to SVN

svn status | grep "^\?" | awk '{ printf("\""); for (f=2; f <= NF; f++) { printf("%s", $f); if (f<NF) printf(" "); } printf("\"\n");}' | xargs svn add

This was based on markb's answer... and a little hunting on the internet. It looks ugly, but it seems to work for me on OS X (including files with spaces).

get parent's view from a layout

If you are trying to find a View from your Fragment then try doing it like this:

int w = ((EditText)getActivity().findViewById(;

AngularJs ReferenceError: $http is not defined

Probably you haven't injected $http service to your controller. There are several ways of doing that.

Please read this reference about DI. Then it gets very simple:

function MyController($scope, $http) {
   // ... your code

What does <value optimized out> mean in gdb?

It didn't. Your compiler did, but there's still a debug symbol for the original variable name.

Sorting objects by property values


This runs on cscript.exe, on windows.

// define the Car class
(function() {
    // makeClass - By John Resig (MIT Licensed)
    // Allows either new User() or User() to be employed for construction.
    function makeClass(){
        return function(args){
            if ( this instanceof arguments.callee ) {
                if ( typeof this.init == "function" )
                    this.init.apply( this, (args && args.callee) ? args : arguments );
            } else
                return new arguments.callee( arguments );

    Car = makeClass();

    Car.prototype.init = function(make, model, price, topSpeed, weight) {
        this.make = make;
        this.model = model;
        this.price = price;
        this.weight = weight;
        this.topSpeed = topSpeed;

// create a list of cars
var autos = [
    new Car("Chevy", "Corvair", 1800, 88, 2900),
    new Car("Buick", "LeSabre", 31000, 138, 3700),
    new Car("Toyota", "Prius", 24000, 103, 3200),
    new Car("Porsche", "911", 92000, 155, 3100),
    new Car("Mercedes", "E500", 67000, 145, 3800),
    new Car("VW", "Passat", 31000, 135, 3700)

// a list of sorting functions
var sorters = {
    byWeight : function(a,b) {
        return (a.weight - b.weight);
    bySpeed : function(a,b) {
        return (a.topSpeed - b.topSpeed);
    byPrice : function(a,b) {
        return (a.price - b.price);
    byModelName : function(a,b) {
        return ((a.model < b.model) ? -1 : ((a.model > b.model) ? 1 : 0));
    byMake : function(a,b) {
        return ((a.make < b.make) ? -1 : ((a.make > b.make) ? 1 : 0));

function say(s) {WScript.Echo(s);}

function show(title)
    say ("sorted by: "+title);
    for (var i=0; i < autos.length; i++) {
        say("  " + autos[i].model);
    say(" ");




You can also make a general sorter.

var byProperty = function(prop) {
    return function(a,b) {
        if (typeof a[prop] == "number") {
            return (a[prop] - b[prop]);
        } else {
            return ((a[prop] < b[prop]) ? -1 : ((a[prop] > b[prop]) ? 1 : 0));

show("Top Speed");

Prevent scroll-bar from adding-up to the Width of page on Chrome

I solved a similar problem I had with scrollbar this way:

First disable vertical scrollbar by setting it's:

overflow-y: hidden;

Then make a div with fixed position with a height equal to the screen height and make it's width thin to look like scrollbar. This div should be vertically scroll-able. Now inside this div make another div with the height of your document (with all it's contents). Now all you need to do is to add an onScroll function to the container div and scroll body as the div scrolls. Here's the code:


<div onscroll="OnScroll(this);" style="width:18px; height:100%;  overflow-y: auto; position: fixed; top: 0; right: 0;">
    <div id="ScrollDiv" style="width:28px; height:100%; overflow-y: auto;">

Then in your page load event add this:


$( document ).ready(function() {
    var body = document.body;
    var html = document.documentElement;
    var height = Math.max( body.scrollHeight, body.offsetHeight, html.clientHeight, html.scrollHeight, html.offsetHeight);
    document.getElementById('ScrollDiv').style.height = height + 'px'; 

function OnScroll(Div) {
    document.body.scrollTop = Div.scrollTop;

Now scrolling the div works just like scrolling the body while body has no scrollbar.

Setting Short Value Java

You can use setTableId((short)100). I think this was changed in Java 5 so that numeric literals assigned to byte or short and within range for the target are automatically assumed to be the target type. That latest J2ME JVMs are derived from Java 4 though.

How do I change Bootstrap 3 column order on mobile layout?

You cannot change the order of columns in smaller screens but you can do that in large screens.

So change the order of your columns.

<!--Main Content-->
<div class="col-lg-9 col-lg-push-3">

<div class="col-lg-3 col-lg-pull-9">

By default this displays the main content first.

So in mobile main content is displayed first.

By using col-lg-push and col-lg-pull we can reorder the columns in large screens and display sidebar on the left and main content on the right.

Working fiddle here.

How do I find all files containing specific text on Linux?

find /path -type f -exec grep -l "string" {} \;

Explanation from comments

find is a command that lets you find files and other objects like directories and links in subdirectories of a given path. If you don't specify a mask that filesnames should meet, it enumerates all directory objects.

-type f specifies that it should proceed only files, not directories etc.
-exec grep specifies that for every found file, it should run grep command, passing its filename as an argument to it, by replacing {} with the filename

Where does MAMP keep its php.ini?

On my mac, running MAMP I have a few locations that would be the likely php.ini, so I edited the memory_limit to different values in the 2 suspected files, to test which one effected the actual MAMP PHP INFO page details. By doing that I was able to determine that this was the correct php.ini: /Applications/MAMP/bin/php/php7.2.10/conf/php.ini

"Uncaught TypeError: undefined is not a function" - Beginner Backbone.js Application

[Joke mode on]

You can fix this by adding this:

import { undefined } from 'undefined-is-a-function';
// Fixed! undefined is now a function.

[joke mode off]

How to use XPath in Python?

Sounds like an lxml advertisement in here. ;) ElementTree is included in the std library. Under 2.6 and below its xpath is pretty weak, but in 2.7+ much improved:

import xml.etree.ElementTree as ET
root = ET.parse(filename)
result = ''

for elem in root.findall('.//child/grandchild'):
    # How to make decisions based on attributes even in 2.6:
    if elem.attrib.get('name') == 'foo':
        result = elem.text

Angular2 If ngModel is used within a form tag, either the name attribute must be set or the form

For everyone who don't panic with the error message itself, but just googling for the explanation why example from here doesn't work (i.e dynamical filtering doesn't occur when the text is typed into the input field): it will not work until you will add the name parameter in the input field. Nothing points to the explanation why pipe isn't working, but the error message points to this topic and fixing it according to the accepted answer makes the dynamical filter working.

Check if a varchar is a number (TSQL)

you can check like this

declare @vchar varchar(50)
set @vchar ='34343';
select case when @vchar not like '%[^0-9]%' then 'Number' else 'Not a Number' end

How to use multiple conditions (With AND) in IIF expressions in ssrs

Here is an example that should give you some idea..

=IIF(First(Fields!Gender.Value,"vw_BrgyClearanceNew")="Female" and 

I think you have to identify the datasource name or the table name where your data is coming from.

Looping through a Scripting.Dictionary using index/item number

According to the documentation of the Item property:

Sets or returns an item for a specified key in a Dictionary object.

In your case, you don't have an item whose key is 1 so doing:

s = d.Item(i)

actually creates a new key / value pair in your dictionary, and the value is empty because you have not used the optional newItem argument.

The Dictionary also has the Items method which allows looping over the indices:

a = d.Items
For i = 0 To d.Count - 1
    s = a(i)
Next i

Regex for Comma delimited list

I suggest you to do in the following way:


which would work for a list containing 1 or more elements.

Import numpy on pycharm

In PyCharm go to

  1. File ? Settings, or use Ctrl + Alt + S
  2. < project name > ? Project Interpreter ? gear symbol ? Add Local
  3. navigate to C:\Miniconda3\envs\my_env\python.exe, where my_env is the environment you want to use

Alternatively, in step 3 use C:\Miniconda3\python.exe if you did not create any further environments (if you never invoked conda create -n my_env python=3).

You can get a list of your current environments with conda info -e and switch to one of them using activate my_env.

How to output MySQL query results in CSV format?

The following bash script works for me. It optionally also gets the schema for the requested tables.

# export mysql data to CSV

#ansi colors
green='\033[0;32m' # '\e[1;32m' is too bright for white bg.

# a colored message 
#   params:
#     1: l_color - the color of the message
#     2: l_msg - the message to display
color_msg() {
  local l_color="$1"
  local l_msg="$2"
  echo -e "${l_color}$l_msg${endColor}"

# error
# show the given error message on stderr and exit
#   params:
#     1: l_msg - the error message to display
error() {
  local l_msg="$1"
  # use ansi red for error
  color_msg $red "Error:" 1>&2
  color_msg $red "\t$l_msg" 1>&2

# display usage 
usage() {
  echo "usage: $0 [-h|--help]" 1>&2
  echo "               -o  | --output      csvdirectory"    1>&2
  echo "               -d  | --database    database"   1>&2
  echo "               -t  | --tables      tables"     1>&2
  echo "               -p  | --password    password"   1>&2
  echo "               -u  | --user        user"       1>&2
  echo "               -hs | --host        host"       1>&2
  echo "               -gs | --get-schema"             1>&2
  echo "" 1>&2
  echo "     output: output csv directory to export mysql data into" 1>&2
  echo "" 1>&2
  echo "         user: mysql user" 1>&2
  echo "     password: mysql password" 1>&2
  echo "" 1>&2
  echo "     database: target database" 1>&2
  echo "       tables: tables to export" 1>&2
  echo "         host: host of target database" 1>&2
  echo "" 1>&2
  echo "  -h|--help: show help" 1>&2
  exit 1

# show help 
help() {
  echo "$0 Help" 1>&2
  echo "===========" 1>&2
  echo "$0 exports a csv file from a mysql database optionally limiting to a list of tables" 1>&2
  echo "   example: $0 --database=cms --user=scott --password=tiger  --tables=person --output person.csv" 1>&2
  echo "" 1>&2

domysql() {
  mysql --host $host -u$user --password=$password $database

getcolumns() {
  local l_table="$1"
  echo "describe $l_table" | domysql | cut -f1 | grep -v "Field" | grep -v "Warning" | paste -sd "," - 2>/dev/null


# parse command line options
while true; do
  #echo "option $1"
  case "$1" in
    # options without arguments
    -h|--help) usage;;
    -d|--database)     database="$2" ; shift ;;
    -t|--tables)       tables="$2" ; shift ;;
    -o|--output)       csvoutput="$2" ; shift ;;
    -u|--user)         user="$2" ; shift ;;
    -hs|--host)        host="$2" ; shift ;;
    -p|--password)     password="$2" ; shift ;;
    -gs|--get-schema)  option="getschema";; 
    (--) shift; break;;
    (-*) echo "$0: error - unrecognized option $1" 1>&2; usage;;
    (*) break;;

# checks
if [ "$csvoutput" == "" ]
  error "ouput csv directory not set"
if [ "$database" == "" ]
  error "mysql database not set"
if [ "$user" == "" ]
  error "mysql user not set"
if [ "$password" == "" ]
  error "mysql password not set"

color_msg $blue "exporting tables of database $database"
if [ "$tables" = "" ]
tables=$(echo "show tables" | domysql)

case $option in
   rm $csvoutput$database.schema
   for table in $tables
     color_msg $blue "getting schema for $table"
     echo -n "$table:" >> $csvoutput$database.schema
     getcolumns $table >> $csvoutput$database.schema
for table in $tables
  color_msg $blue "exporting table $table"
  cols=$(grep "$table:" $csvoutput$database.schema | cut -f2 -d:)
  if [  "$cols" = "" ]
    cols=$(getcolumns $table)
  ssh $host rm $mysqlfiles/$table.csv
cat <<EOF | mysql --host $host -u$user --password=$password $database 
SELECT $cols FROM $table INTO OUTFILE '$mysqlfiles$table.csv'
  scp $host:$mysqlfiles/$table.csv $csvoutput$table.csv.raw
  (echo "$cols"; cat $csvoutput$table.csv.raw) > $csvoutput$table.csv
  rm $csvoutput$table.csv.raw

When do items in HTML5 local storage expire?

For the benefit of searchers:

Like Fernando, I didn't want to add a load of json when the values stored were simple. I just needed to track some UI interaction and keep the data relevant (e.g. how a user used an ecommerce site before checking out).

This will not meet everyones criteria, but will hopefully be a quick copy+paste starter for someone and save adding another lib.

NOTE: This would not be good if you need to retrieve the items individually.

// Addition
    localStorage.setItem('myapp-' + new Date().getTime(), 'my value');

// Removal of all expired items

    // two mins - (1000 * 60 * 20) would be 20 mins
    var expiryTime = new Date().getTime() - (1000 * 60 * 2);

    var deleteRows = [];
    for(var i=0; i < localStorage.length; i++){
        var key = localStorage.key(i);
        var partsArray = key.split('-');
        // The last value will be a timestamp
        var lastRow = partsArray[partsArray.length - 1];

        if(lastRow && parseInt(lastRow) < expiryTime){
    // delete old data
    for(var j=0; j < deleteRows.length; j++){

How do you handle a "cannot instantiate abstract class" error in C++?

An abstract class cannot be instantiated by definition. In order to use this class, you must create a concrete subclass which implements all virtual functions of the class. In this case, you most likely have not implemented all the virtual functions declared in Light. This means that AmbientOccluder defaults to an abstract class. For us to further help you, you should include the details of the Light class.

How to check model string property for null in a razor view

Try this first, you may be passing a Null Model:

@if (Model != null && !String.IsNullOrEmpty(Model.ImageName))
    <label for="Image">Change picture</label>
    <label for="Image">Add picture</label>

Otherise, you can make it even neater with some ternary fun! - but that will still error if your model is Null.

<label for="Image">@(String.IsNullOrEmpty(Model.ImageName) ? "Add" : "Change") picture</label>

jQuery: Scroll down page a set increment (in pixels) on click?

You might be after something that the scrollTo plugin from Ariel Flesler does really well.

Styling Google Maps InfoWindow

I have design google map infowindow with image & some content as per below.

enter image description here

map_script (Just for infowindow html reference)

for (i = 0; i < locations.length; i++) { 
    var latlng = new google.maps.LatLng(locations[i][1], locations[i][2]);
    marker = new google.maps.Marker({
        position: latlng,
        map: map,
        icon: "<?php echo plugins_url( 'assets/img/map-pin.png', ELEMENTOR_ES__FILE__ ); ?>"

    var property_img = locations[i][6],
    title = locations[i][0],
    price = locations[i][3],
    bedrooms = locations[i][4],
    type = locations[i][5],
    listed_on = locations[i][7],
    prop_url = locations[i][8];

    content = "<div class='map_info_wrapper'><a href="+prop_url+"><div class='img_wrapper'><img src="+property_img+"></div>"+
    "<div class='property_content_wrap'>"+
    "<div class='property_title'>"+

    "<div class='property_price'>"+

    "<div class='property_bed_type'>"+

    "<div class='property_listed_date'>"+
    "<span>Listed on "+listed_on+"</span>"+

    google.maps.event.addListener(marker, 'click', (function(marker, content, i) {
        return function() {
  , marker);
    })(marker, content, i));

Most important thing is CSS

 #propertymap .gm-style-iw{
    font-family: "Georgia", "Open Sans", Sans-serif;
    text-align: center;
    width: 100% !important;
    border-radius: 0;
    left: 0 !important;
    top: 20px !important;

 #propertymap .gm-style > div > div > div > div > div > div > div {
    background: none!important;

.gm-style > div > div > div > div > div > div > div:nth-child(2) {
     box-shadow: none!important;
 #propertymap .gm-style-iw > div > div{
    background: #FFF!important;

 #propertymap .gm-style-iw a{
    text-decoration: none;

 #propertymap .gm-style-iw > div{
    width: 245px !important

 #propertymap .gm-style-iw .img_wrapper {
    height: 150px;  
    overflow: hidden;
    width: 100%;
    text-align: center;
    margin: 0px auto;

 #propertymap .gm-style-iw .img_wrapper > img {
    width: 100%;

 #propertymap .gm-style-iw .property_content_wrap {
    padding: 0px 20px;

 #propertymap .gm-style-iw .property_title{
    min-height: auto;

What can cause a “Resource temporarily unavailable” on sock send() command

Let'e me give an example:

  1. client connect to server, and send 1MB data to server every 1 second.

  2. server side accept a connection, and then sleep 20 second, without recv msg from client.So the tcp send buffer in the client side will be full.

Code in client side:

#include <arpa/inet.h>
#include <sys/socket.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#define exit_if(r, ...)                                                                          \
    if (r) {                                                                                     \
        printf(__VA_ARGS__);                                                                     \
        printf("%s:%d error no: %d error msg %s\n", __FILE__, __LINE__, errno, strerror(errno)); \
        exit(1);                                                                                 \

void setNonBlock(int fd) {
    int flags = fcntl(fd, F_GETFL, 0);
    exit_if(flags < 0, "fcntl failed");
    int r = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
    exit_if(r < 0, "fcntl failed");

void test_full_sock_buf_1(){
    short port = 8000;
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;

    int fd = socket(AF_INET, SOCK_STREAM, 0);
    exit_if(fd<0, "create socket error");

    int ret = connect(fd, (struct sockaddr *) &addr, sizeof(struct sockaddr));
    exit_if(ret<0, "connect to server error");

    printf("connect to server success");

    const int LEN = 1024 * 1000;
    char msg[LEN];  // 1MB data
    memset(msg, 'a', LEN);

    for (int i = 0; i < 1000; ++i) {
        int len = send(fd, msg, LEN, 0);
        printf("send: %d, erron: %d, %s \n", len, errno, strerror(errno));


int main(){

    return 0;

Code in server side:

    #include <arpa/inet.h>
    #include <sys/socket.h>
    #include <stdio.h>
    #include <errno.h>
    #include <fcntl.h>
    #include <stdlib.h>
    #include <string.h>
    #define exit_if(r, ...)                                                                          \
        if (r) {                                                                                     \
            printf(__VA_ARGS__);                                                                     \
            printf("%s:%d error no: %d error msg %s\n", __FILE__, __LINE__, errno, strerror(errno)); \
            exit(1);                                                                                 \
void test_full_sock_buf_1(){

    int listenfd = socket(AF_INET, SOCK_STREAM, 0);
    exit_if(listenfd<0, "create socket error");

    short port = 8000;
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;

    int r = ::bind(listenfd, (struct sockaddr *) &addr, sizeof(struct sockaddr));
    exit_if(r<0, "bind socket error");

    r = listen(listenfd, 100);
    exit_if(r<0, "listen socket error");

    struct sockaddr_in raddr;
    socklen_t rsz = sizeof(raddr);
    int cfd = accept(listenfd, (struct sockaddr *) &raddr, &rsz);
    exit_if(cfd<0, "accept socket error");

    sockaddr_in peer;
    socklen_t alen = sizeof(peer);
    getpeername(cfd, (sockaddr *) &peer, &alen);

    printf("accept a connection from %s:%d\n", inet_ntoa(peer.sin_addr), ntohs(peer.sin_port));

    printf("but now I will sleep 15 second, then exit");

Start server side, then start client side.

server side may output:

accept a connection from
but now I will sleep 15 second, then exit
Process finished with exit code 0

enter image description here

client side may output:

connect to server successsend: 1024000, erron: 0, Success 
send: 1024000, erron: 0, Success 
send: 1024000, erron: 0, Success 
send: 552190, erron: 0, Success 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 11, Resource temporarily unavailable 
send: -1, erron: 104, Connection reset by peer 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 
send: -1, erron: 32, Broken pipe 

enter image description here

You can see, as the server side doesn't recv the data from client, so when the client side tcp buffer get full, but you still send data, so you may get Resource temporarily unavailable error.

JavaScript Loading Screen while page loads

At the beginning of your loading script, just make your

visible through css [display:block;] and make the rest of the page invisible through css[display:none;].

Once the loading is done, just make the loading invisible and the page visible again with the same technique. You can use the document.getElementById() to select the divs you want to change the display.

Edit: Here's what it would sort of look like. When the body finishes loading, it will call the javascript function that will change the display values of the different elements. By default, your style would be to have the page not visible the loading visible.

            display: none;
            display: block;
        function myFunction()
            document.getElementById("page").style.display = "block";
            document.getElementById("loading").style.display = "none";

<body onload="myFunction()">
    <div id="page">

    <div id="loading">


Requested bean is currently in creation: Is there an unresolvable circular reference?

In my case, I was defining a bean and autowiring it in the constructor of the same class file.

public class MyApplication {
    private MyBean myBean;

    public MyApplication(MyBean myBean) {
        this.myBean = myBean;

    public MyBean myBean() {
        return new MyBean();

My solution was to move the bean definition to another class file.

public CustomConfig {
    public MyBean myBean() {
        return new MyBean();

How do I get a platform-dependent new line character?

If you're trying to write a newline to a file, you could simply use BufferedWriter's newLine() method.

How to reverse apply a stash?

This is in addition to the above answers but adds search for the git stash based on the message as the stash number can change when new stashes are saved. I have written a couple of bash functions:

  if [ "$1" ]; then
    git stash apply `git stash list | grep -oPm1 "(.*)(?=:.*:.*$1.*)"`
  if [ "$1" ]; then
    git stash show -p `git stash list | grep -oPm1 "(.*)(?=:.*:.*$1.*)"` | git apply -R
    git status
  1. Create stash with name (message) $ git stash save "my stash"
  2. To appply named $ apply "my stash"
  3. To remove named stash $ remove "my stash"

Check for database connection, otherwise display message

very basic:

$username = 'user';
$password = 'password';
$server = 'localhost'; 
// Opens a connection to a MySQL server
$connection = mysql_connect ($server, $username, $password) or die('try again in some minutes, please');
//if you want to suppress the error message, substitute the connection line for:
//$connection = @mysql_connect($server, $username, $password) or die('try again in some minutes, please');


Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'user'@'localhost' (using password: YES) in /home/user/public_html/zdel1.php on line 6 try again in some minutes, please

as per Wrikken's recommendation below, check out a complete error handler for more complex, efficient and elegant solutions:

Why use Ruby's attr_accessor, attr_reader and attr_writer?

All of the answers above are correct; attr_reader and attr_writer are more convenient to write than manually typing the methods they are shorthands for. Apart from that they offer much better performance than writing the method definition yourself. For more info see slide 152 onwards from this talk (PDF) by Aaron Patterson.

Display Image On Text Link Hover CSS Only


.hover_img a:hover span {
    display: block;
    width: 350px;

to show hover image full size in table change 350 to your size.

ssl_error_rx_record_too_long and Apache SSL

In my case I had forgot to set SSLEngine On in the configuration. Like so,

<VirtualHost _default_:443>
  SSLEngine On

Passing structs to functions

bool data(sampleData *data)

You need to tell the method which type of struct you are using. In this case, sampleData.

Note: In this case, you will need to define the struct prior to the method for it to be recognized.


struct sampleData
   int N;
   int M;
   // ...

bool data(struct *sampleData)


int main(int argc, char *argv[]) {

      sampleData sd;


Note 2: I'm a C guy. There may be a more c++ish way to do this.

How to find out client ID of component for ajax update/render? Cannot find component with expression "foo" referenced from "bar"

first of all: as far as i know placing dialog inside a tabview is a bad practice... you better take it out...

and now to your question:

sorry, took me some time to get what exactly you wanted to implement,

did at my web app myself just now, and it works

as I sayed before place the p:dialog out side the `p:tabView ,

leave the p:dialog as you initially suggested :

<p:dialog modal="true" widgetVar="dlg">
    <h:panelGrid id="display">
        <h:outputText value="Name:" />
        <h:outputText value="#{}" />

and the p:commandlink should look like this (all i did is to change the update attribute)

<p:commandLink update="display" oncomplete="">
    <f:setPropertyActionListener value="#{lndInstrument}" 
        target="#{instrumentBean.selectedInstrument}" />
    <h:outputText value="#{}" />

the same works in my web app, and if it does not work for you , then i guess there is something wrong in your java bean code...

How do I print my Java object without getting "SomeType@2f92e0f4"?

If you look at the Object class (Parent class of all classes in Java) the toString() method implementation is

    public String toString() {
       return getClass().getName() + "@" + Integer.toHexString(hashCode());

whenever you print any object in Java then toString() will be call. Now it's up to you if you override toString() then your method will call other Object class method call.

How do I pass data between Activities in Android application?

It helps me to see things in context. Here are two examples.

Passing Data Forward

enter image description here

Main Activity

  • Put the data you want to send in an Intent with a key-value pair. See this answer for naming conventions for the key.
  • Start the Second Activity with startActivity.

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {

    // "Go to Second Activity" button click
    public void onButtonClick(View view) {

        // get the text to pass
        EditText editText = (EditText) findViewById(;
        String textToPass = editText.getText().toString();

        // start the SecondActivity
        Intent intent = new Intent(this, SecondActivity.class);
        intent.putExtra(Intent.EXTRA_TEXT, textToPass);

Second Activity

  • You use getIntent() to get the Intent that started the second activity. Then you can extract the data with getExtras() and the key you defined in the first activity. Since our data is a String we will just use getStringExtra here.

public class SecondActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {

        // get the text from MainActivity
        Intent intent = getIntent();
        String text = intent.getStringExtra(Intent.EXTRA_TEXT);

        // use the text in a TextView
        TextView textView = (TextView) findViewById(;

Passing Data Back

enter image description here

Main Activity

  • Start the Second Activity with startActivityForResult, providing it an arbitrary result code.
  • Override onActivityResult. This is called when the Second Activity finishes. You can make sure that it is actually the Second Activity by checking the result code. (This is useful when you are starting multiple different activities from the same main activity.)
  • Extract the data you got from the return Intent. The data is extracted using a key-value pair. I could use any string for the key but I'll use the predefined Intent.EXTRA_TEXT since I'm sending text.

public class MainActivity extends AppCompatActivity {

    private static final int SECOND_ACTIVITY_REQUEST_CODE = 0;

    protected void onCreate(Bundle savedInstanceState) {

    // "Go to Second Activity" button click
    public void onButtonClick(View view) {

        // Start the SecondActivity
        Intent intent = new Intent(this, SecondActivity.class);
        startActivityForResult(intent, SECOND_ACTIVITY_REQUEST_CODE);

    // This method is called when the second activity finishes
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // check that it is the SecondActivity with an OK result
        if (requestCode == SECOND_ACTIVITY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {

                // get String data from Intent
                String returnString = data.getStringExtra(Intent.EXTRA_TEXT);

                // set text view with string
                TextView textView = (TextView) findViewById(;

Second Activity

  • Put the data that you want to send back to the previous activity into an Intent. The data is stored in the Intent using a key-value pair. I chose to use Intent.EXTRA_TEXT for my key.
  • Set the result to RESULT_OK and add the intent holding your data.
  • Call finish() to close the Second Activity.

public class SecondActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {

    // "Send text back" button click
    public void onButtonClick(View view) {

        // get the text from the EditText
        EditText editText = (EditText) findViewById(;
        String stringToPassBack = editText.getText().toString();

        // put the String to pass back into an Intent and close this activity
        Intent intent = new Intent();
        intent.putExtra(Intent.EXTRA_TEXT, stringToPassBack);
        setResult(RESULT_OK, intent);

Drop rows with all zeros in pandas data frame

To drop all columns with values 0 in any row:

new_df = df[df.loc[:]!=0].dropna()

Call a function after previous function is complete

This answer uses promises, a JavaScript feature of the ECMAScript 6 standard. If your target platform does not support promises, polyfill it with PromiseJs.

Promises are a new (and a lot better) way to handle asynchronous operations in JavaScript:

    if (condition == 'true'){
        function1(someVariable).then(function() {
            //this function is executed after function1
    else {

function function1(param, callback) {
    return new Promise(function (fulfill, reject){
        //do stuff
        fulfill(result); //if the action succeeded
        reject(error); //if the action did not succeed

This may seem like a significant overhead for this simple example, but for more complex code it is far better than using callbacks. You can easily chain multiple asynchronous calls using multiple then statements:

function1(someVariable).then(function() {
}).then(function() {

You can also wrap jQuery deferrds easily (which are returned from $.ajax calls):

Promise.resolve($.ajax(...params...)).then(function(result) {
    //whatever you want to do after the request

As @charlietfl noted, the jqXHR object returned by $.ajax() implements the Promise interface. So it is not actually necessary to wrap it in a Promise, it can be used directly:

$.ajax(...params...).then(function(result) {
    //whatever you want to do after the request

Delegation: EventEmitter or Observable in Angular

Update 2016-06-27: instead of using Observables, use either

  • a BehaviorSubject, as recommended by @Abdulrahman in a comment, or
  • a ReplaySubject, as recommended by @Jason Goemaat in a comment

A Subject is both an Observable (so we can subscribe() to it) and an Observer (so we can call next() on it to emit a new value). We exploit this feature. A Subject allows values to be multicast to many Observers. We don't exploit this feature (we only have one Observer).

BehaviorSubject is a variant of Subject. It has the notion of "the current value". We exploit this: whenever we create an ObservingComponent, it gets the current navigation item value from the BehaviorSubject automatically.

The code below and the plunker use BehaviorSubject.

ReplaySubject is another variant of Subject. If you want to wait until a value is actually produced, use ReplaySubject(1). Whereas a BehaviorSubject requires an initial value (which will be provided immediately), ReplaySubject does not. ReplaySubject will always provide the most recent value, but since it does not have a required initial value, the service can do some async operation before returning it's first value. It will still fire immediately on subsequent calls with the most recent value. If you just want one value, use first() on the subscription. You do not have to unsubscribe if you use first().

import {Injectable}      from '@angular/core'
import {BehaviorSubject} from 'rxjs/BehaviorSubject';

export class NavService {
  // Observable navItem source
  private _navItemSource = new BehaviorSubject<number>(0);
  // Observable navItem stream
  navItem$ = this._navItemSource.asObservable();
  // service command
  changeNav(number) {;
import {Component}    from '@angular/core';
import {NavService}   from './nav.service';
import {Subscription} from 'rxjs/Subscription';

  selector: 'obs-comp',
  template: `obs component, item: {{item}}`
export class ObservingComponent {
  item: number;
  constructor(private _navService:NavService) {}
  ngOnInit() {
    this.subscription = this._navService.navItem$
       .subscribe(item => this.item = item)
  ngOnDestroy() {
    // prevent memory leak when component is destroyed
  selector: 'my-nav',
    <div class="nav-item" (click)="selectedNavItem(1)">nav 1 (click me)</div>
    <div class="nav-item" (click)="selectedNavItem(2)">nav 2 (click me)</div>`
export class Navigation {
  item = 1;
  constructor(private _navService:NavService) {}
  selectedNavItem(item: number) {
    console.log('selected nav item ' + item);


Original answer that uses an Observable: (it requires more code and logic than using a BehaviorSubject, so I don't recommend it, but it may be instructive)

So, here's an implementation that uses an Observable instead of an EventEmitter. Unlike my EventEmitter implementation, this implementation also stores the currently selected navItem in the service, so that when an observing component is created, it can retrieve the current value via API call navItem(), and then be notified of changes via the navChange$ Observable.

import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/share';
import {Observer} from 'rxjs/Observer';

export class NavService {
  private _navItem = 0;
  navChange$: Observable<number>;
  private _observer: Observer;
  constructor() {
    this.navChange$ = new Observable(observer =>
      this._observer = observer).share();
    // share() allows multiple subscribers
  changeNav(number) {
    this._navItem = number;;
  navItem() {
    return this._navItem;

  selector: 'obs-comp',
  template: `obs component, item: {{item}}`
export class ObservingComponent {
  item: number;
  subscription: any;
  constructor(private _navService:NavService) {}
  ngOnInit() {
    this.item = this._navService.navItem();
    this.subscription = this._navService.navChange$.subscribe(
      item => this.selectedNavItem(item));
  selectedNavItem(item: number) {
    this.item = item;
  ngOnDestroy() {

  selector: 'my-nav',
    <div class="nav-item" (click)="selectedNavItem(1)">nav 1 (click me)</div>
    <div class="nav-item" (click)="selectedNavItem(2)">nav 2 (click me)</div>
export class Navigation {
  constructor(private _navService:NavService) {}
  selectedNavItem(item: number) {
    console.log('selected nav item ' + item);


See also the Component Interaction Cookbook example, which uses a Subject in addition to observables. Although the example is "parent and children communication," the same technique is applicable for unrelated components.

Python nonlocal statement

A google search for "python nonlocal" turned up the Proposal, PEP 3104, which fully describes the syntax and reasoning behind the statement. in short, it works in exactly the same way as the global statement, except that it is used to refer to variables that are neither global nor local to the function.

Here's a brief example of what you can do with this. The counter generator can be rewritten to use this so that it looks more like the idioms of languages with closures.

def make_counter():
    count = 0
    def counter():
        nonlocal count
        count += 1
        return count
    return counter

Obviously, you could write this as a generator, like:

def counter_generator():
    count = 0
    while True:
        count += 1
        yield count

But while this is perfectly idiomatic python, it seems that the first version would be a bit more obvious for beginners. Properly using generators, by calling the returned function, is a common point of confusion. The first version explicitly returns a function.

How to convert a JSON string to a dictionary?

let JSONData = .utf8)!

let jsonResult = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves)

guard let userDictionary = jsonResult as? Dictionary<String, AnyObject> else {
            throw NSError()}

Class Not Found Exception when running JUnit test

NoClassDefFoundError really means it can't initilize the class. It has nothing to do with finding the class. I got this error when calling trim() on a null String.

JUnit won't show NullPointerException. The string isn't null when running normally because I'm fetching the string from a properties file which is not availible for tests.

My advice is to remove pieces from the class until your tests start passing. Then you can determine which line is giving the error.

In C#, should I use string.Empty or String.Empty or "" to intitialize a string?

I personally prefer "" unless there is a good reason to something more complex.

VBA EXCEL To Prompt User Response to Select Folder and Return the Path as String Variable


Function GetFolder() As String
    Dim fldr As FileDialog
    Dim sItem As String
    Set fldr = Application.FileDialog(msoFileDialogFolderPicker)
    With fldr
        .Title = "Select a Folder"
        .AllowMultiSelect = False
        .InitialFileName = Application.DefaultFilePath
        If .Show <> -1 Then GoTo NextCode
        sItem = .SelectedItems(1)
    End With
    GetFolder = sItem
    Set fldr = Nothing
End Function

This code was adapted from Ozgrid

and as jkf points out, from Mr Excel

Why would one mark local variables and method parameters as "final" in Java?

final has three good reasons:

  • instance variables set by constructor only become immutable
  • methods not to be overridden become final, use this with real reasons, not by default
  • local variables or parameters to be used in anonimous classes inside a method need to be final

Like methods, local variables and parameters need not to be declared final. As others said before, this clutters the code becoming less readable with very little efford for compiler performace optimisation, this is no real reason for most code fragments.

How to write to file in Ruby?

To destroy the previous contents of the file, then write a new string to the file:

open('myfile.txt', 'w') { |f| f << "some text or data structures..." } 

To append to a file without overwriting its old contents:

open('myfile.txt', "a") { |f| f << 'I am appended string' } 

What is a vertical tab?

The ASCII vertical tab (\x0B)is still used in some databases and file formats as a new line WITHIN a field. For example:

String to char array Java

A string to char array is as simple as

String str = "someString"; 
char[] charArray = str.toCharArray();

Can you explain a little more on what you are trying to do?

* Update *

if I am understanding your new comment, you can use a byte array and example is provided.

byte[] bytes = ByteBuffer.allocate(4).putInt(1695609641).array();

for (byte b : bytes) {
   System.out.format("0x%x ", b);

With the following output

0x65 0x10 0xf3 0x29

Is there a label/goto in Python?

In lieu of a python goto equivalent I use the break statement in the following fashion for quick tests of my code. This assumes you have structured code base. The test variable is initialized at the start of your function and I just move the "If test: break" block to the end of the nested if-then block or loop I want to test, modifying the return variable at the end of the code to reflect the block or loop variable I'm testing.

def x:
  test = True
  If y:
     # some code
     If test:
  return something

Automated testing for REST Api

At my work we have recently put together a couple of test suites written in Java to test some RESTful APIs we built. Our Services could invoke other RESTful APIs they depend on. We split it into two suites.

  • Suite 1 - Testing each service in isolation
    • Mock any peer services the API depends on using restito. Other alternatives include rest-driver, wiremock and betamax.
    • Tests the service we are testing and the mocks all run in a single JVM
    • Launches the service in Jetty

I would definitely recommend doing this. It has worked really well for us. The main advantages are:

  • Peer services are mocked, so you needn't perform any complicated data setup. Before each test you simply use restito to define how you want peer services to behave, just like you would with classes in unit tests with Mockito.
  • You can ask the mocked peer services if they were called. You can't do these asserts as easily with real peer services.
  • The suite is super fast as mocked services serve pre-canned in-memory responses. So we can get good coverage without the suite taking an age to run.
  • The suite is reliable and repeatable as its isolated in it's own JVM, so no need to worry about other suites/people mucking about with an shared environment at the same time the suite is running and causing tests to fail.

  • Suite 2 - Full End to End
    • Suite runs against a full environment deployed across several machines
    • API deployed on Tomcat in environment
    • Peer services are real 'as live' full deployments

This suite requires us to do data set up in peer services which means tests generally take more time to write. As much as possible we use REST clients to do data set up in peer services.

Tests in this suite usually take longer to write, so we put most of our coverage in Suite 1. That being said there is still clear value in this suite as our mocks in Suite 1 may not be behaving quite like the real services.

how to include glyphicons in bootstrap 3

I think your particular problem isn't how to use Glyphicons but understanding how Bootstrap files work together.

Bootstrap requires a specific file structure to work. I see from your code you have this:

<link href="bootstrap.css" rel="stylesheet" media="screen">

Your Bootstrap.css is being loaded from the same location as your page, this would create a problem if you didn't adjust your file structure.

But first, let me recommend you setup your folder structure like so:

/css      <-- Bootstrap.css here
/fonts    <-- Bootstrap fonts here
/js       <-- Bootstrap JavaScript here

If you notice, this is also how Bootstrap structures its files in its download ZIP.

You then include your Bootstrap file like so:

<link href="css/bootstrap.css" rel="stylesheet" media="screen">
<link href="./css/bootstrap.css" rel="stylesheet" media="screen">
<link href="/css/bootstrap.css" rel="stylesheet" media="screen">

Depending on your server structure or what you're going for.

The first and second are relative to your file's current directory. The second one is just more explicit by saying "here" (./) first then css folder (/css).

The third is good if you're running a web server, and you can just use relative to root notation as the leading "/" will be always start at the root folder.

So, why do this?

Bootstrap.css has this specific line for Glyphfonts:

@font-face {
    font-family: 'Glyphicons Halflings';
    src: url('../fonts/glyphicons-halflings-regular.eot');
    src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons-halflingsregular') format('svg');

What you can see is that that Glyphfonts are loaded by going up one directory ../ and then looking for a folder called /fonts and THEN loading the font file.

The URL address is relative to the location of the CSS file. So, if your CSS file is at the same location like this:


The CSS file is going one level deeper than looking for a /fonts folder.

So, let's say the actual location of these files are:


The CSS file would technically be looking for a folder at:


but your folder is actually in:


So see if that helps. You don't have to do anything 'special' to load Bootstrap Glyphicons, except make sure your folder structure is set up appropriately.

When you get that fixed, your HTML should simply be:

<span class="glyphicon glyphicon-comment"></span>

Note, you need both classes. The first class glyphicon sets up the basic styles while glyphicon-comment sets the specific image.

Posting parameters to a url using the POST method without using a form

it can be done with CURL or AJAX. The response is equally cryptic as the answer.

Converting an int to a binary string representation in Java?

You should really use Integer.toBinaryString() (as shown above), but if for some reason you want your own:

// Like Integer.toBinaryString, but always returns 32 chars
public static String asBitString(int value) {
  final char[] buf = new char[32];
  for (int i = 31; i >= 0; i--) {
    buf[31 - i] = ((1 << i) & value) == 0 ? '0' : '1';
  return new String(buf);

Git command to checkout any branch and overwrite local changes

The new git-switch command (starting in GIT 2.23) also has a flag --discard-changes which should help you. git pull might be necessary afterwards.

Warning: it's still considered to be experimental.

Add column with number of days between dates in DataFrame pandas

To remove the 'days' text element, you can also make use of the dt() accessor for series:


df[['A','B']] = df[['A','B']].apply(pd.to_datetime) #if conversion required
df['C'] = (df['B'] - df['A']).dt.days

which returns:

             A          B   C
one 2014-01-01 2014-02-28  58
two 2014-02-03 2014-03-01  26

How to capture Curl output to a file?

use --trace-asci output.txt can output the curl details to the output.txt

reading text file with utf-8 encoding using java

You are reading the file right but the problem seems to be with the default encoding of System.out. Try this to print the UTF-8 string-

PrintStream out = new PrintStream(System.out, true, "UTF-8");

Visual Studio Code PHP Intelephense Keep Showing Not Necessary Error

Here is I solved:

Open the extension settings:

enter image description here

And search for the variable you want to change, and unchecked/checked it

enter image description here

The variables you should consider are:


how to use LIKE with column name

declare @LkeVal as Varchar(100)
declare @LkeSelect Varchar(100)

Set @LkeSelect = (select top 1 <column> from <table> where <column> = 'value')
Set @LkeVal = '%' + @LkeSelect

select * from <table2> where <column2> like(''+@LkeVal+'');

Why do we have to specify FromBody and FromUri?

The default behavior is:

  1. If the parameter is a primitive type (int, bool, double, ...), Web API tries to get the value from the URI of the HTTP request.

  2. For complex types (your own object, for example: Person), Web API tries to read the value from the body of the HTTP request.

So, if you have:

  • a primitive type in the URI, or
  • a complex type in the body

...then you don't have to add any attributes (neither [FromBody] nor [FromUri]).

But, if you have a primitive type in the body, then you have to add [FromBody] in front of your primitive type parameter in your WebAPI controller method. (Because, by default, WebAPI is looking for primitive types in the URI of the HTTP request.)

Or, if you have a complex type in your URI, then you must add [FromUri]. (Because, by default, WebAPI is looking for complex types in the body of the HTTP request by default.)

Primitive types:

public class UsersController : ApiController
    // api/users
    public HttpResponseMessage Post([FromBody]int id)

    // api/users/id
    public HttpResponseMessage Post(int id)


Complex types:

public class UsersController : ApiController
    // api/users
    public HttpResponseMessage Post(User user)


    // api/users/user
    public HttpResponseMessage Post([FromUri]User user)


This works as long as you send only one parameter in your HTTP request. When sending multiple, you need to create a custom model which has all your parameters like this:

public class MyModel
    public string MyProperty { get; set; }
    public string MyProperty2 { get; set; }

public async Task<dynamic> Search([FromBody] MyModel model)
    // model.MyProperty;
    // model.MyProperty2;

From Microsoft's documentation for parameter binding in ASP.NET Web API:

When a parameter has [FromBody], Web API uses the Content-Type header to select a formatter. In this example, the content type is "application/json" and the request body is a raw JSON string (not a JSON object). At most one parameter is allowed to read from the message body.

This should work:

public HttpResponseMessage Post([FromBody] string name) { ... }

This will not work:

// Caution: This won't work!    
public HttpResponseMessage Post([FromBody] int id, [FromBody] string name) { ... }

The reason for this rule is that the request body might be stored in a non-buffered stream that can only be read once.

python: how to send mail with TO, CC and BCC?

It did not worked for me until i created:

#created cc string
cc = ""[email protected];
#added cc to header
msg['Cc'] = cc

and than added cc in recipient [list] like:

s.sendmail(me, [you,cc], msg.as_string())

How to view transaction logs in SQL Server 2008

I accidentally deleted a whole bunch of data in the wrong environment and this post was one of the first ones I found.

Because I was simultaneously panicking and searching for a solution, I went for the first thing I saw - ApexSQL Logs, which was $2000 which was an acceptable cost.

However, I've since found out that Toad for Sql Server can generate undo scripts from transaction logs and it is only $655.

Lastly, found an even cheaper option SysToolsGroup Log Analyzer and it is only $300.

failed to open stream: No such file or directory in

you can use:

define("PATH_ROOT", dirname(__FILE__));
include_once PATH_ROOT . "/PoliticalForum/headerSite.php";

How to use Boost in Visual Studio 2010

Download boost from: e.g. by svn

  • Windows -> tortoise (the simplest way)

After that : cmd -> go to boost directory ("D:\boostTrunk" - where You checkout or download and extract package): command : bootstrap

we created bjam.exe in ("D:\boostTrunk") After that : command : bjam toolset=msvc-10.0 variant=debug,release threading=multi link=static (It will take some time ~20min.)

After that: Open Visual studio 2010 -> create empty project -> go to project properties -> set:

Project properties VS 2010

Paste this code and check if it is working?

#include <iostream>
#include <boost/shared_ptr.hpp>
#include <boost/regex.hpp>

using namespace std;

struct Hello 
        cout << "Hello constructor" << endl;

        cout << "Hello destructor" << endl;

int main(int argc, char**argv)
    //Boost regex, compiled library
    boost::regex regex("^(Hello|Bye) Boost$");
    boost::cmatch helloMatches;
    boost::regex_search("Hello Boost", helloMatches, regex);
    cout << "The word between () is: " << helloMatches[1] << endl;

    //Boost shared pointer, header only library
    boost::shared_ptr<Hello> sharedHello(new Hello);

    return 0;

Resources :

Ignoring a class property in Entity Framework 4.1 Code First

As of EF 5.0, you need to include the System.ComponentModel.DataAnnotations.Schema namespace.

Is true == 1 and false == 0 in JavaScript?

From the ECMAScript specification, Section 11.9.3 The Abstract Equality Comparison Algorithm:

The comparison x == y, where x and y are values, produces true or false. Such a comparison is performed as follows:

  • If Type(y) is Boolean, return the result of the comparison x == ToNumber(y).

Thus, in, if (1 == true), true gets coerced to a Number, i.e. Number(true), which results in the value of 1, yielding the final if (1 == 1) which is true.

if (0 == false) is the exact same logic, since Number(false) == 0.

This doesn't happen when you use the strict equals operator === instead:

11.9.6 The Strict Equality Comparison Algorithm

The comparison x === y, where x and y are values, produces true or false. Such a comparison is performed as follows:

  • If Type(x) is different from Type(y), return false.

JSONDecodeError: Expecting value: line 1 column 1

If you look at the output you receive from print() and also in your Traceback, you'll see the value you get back is not a string, it's a bytes object (prefixed by b):

b'{\n  "note":"This file    .....

If you fetch the URL using a tool such as curl -v, you will see that the content type is

Content-Type: application/json; charset=utf-8

So it's JSON, encoded as UTF-8, and Python is considering it a byte stream, not a simple string. In order to parse this, you need to convert it into a string first.

Change the last line of code to this:

info = json.loads(js.decode("utf-8"))

Where is the web server root directory in WAMP?

To check what is your root directory go to httpd.conf file of apache and search for "DocumentRoot".The location following it is your root directory

Creating a Jenkins environment variable using Groovy

My environment was prior tooling such as Jenkins and was running with batch files (I know, I'm old). So those batch files (and their sub-batch files) are using environment variables. This was my piece of groovy script which injects environment variables. The names and parameters used are dummy ones.

// The process/batch which uses environment variables
def buildLabel = "SomeVersionNr"
def script = "startBuild.bat"
def processBuilder = new ProcessBuilder(script, buildLabel)

//Inject our environment variables
Map<String, String> env = processBuilder.environment()
env.put("ProjectRoot", "someLocation")
env.put("SomeVar", "Some")

Process p = processBuilder.start()

Of course if you set Jenkins up from scratch you would probably do it differently and share the variables in another way, or pass parameters around but this might come handy.

Regex for 1 or 2 digits, optional non-alphanumeric, 2 known alphas


\d defines a number and {1,2} means 1 or two of the expression before, \W defines a non word character.

How to add border around linear layout except at the bottom?

Create an XML file named border.xml in the drawable folder and put the following code in it.

 <?xml version="1.0" encoding="utf-8"?>
 <layer-list xmlns:android="">
    <shape android:shape="rectangle">
      <solid android:color="#FF0000" /> 
    <item android:left="5dp" android:right="5dp"  android:top="5dp" >  
     <shape android:shape="rectangle"> 
      <solid android:color="#000000" />

Then add a background to your linear layout like this:



This XML was tested with a galaxy s running GingerBread 2.3.3 and ran perfectly as shown in image below:

enter image description here


tested with galaxy s 3 running JellyBean 4.1.2 and ran perfectly as shown in image below :

enter image description here

Finally its works perfectly with all APIs

EDIT 2 :

It can also be done using a stroke to keep the background as transparent while still keeping a border except at the bottom with the following code.

<?xml version="1.0" encoding="utf-8"?>
 <layer-list xmlns:android="">
   <item android:left="0dp" android:right="0dp"  android:top="0dp"  
    <shape android:shape="rectangle">
     <stroke android:width="10dp" android:color="#B22222" />

hope this help .

how to add new <li> to <ul> onclick with javascript

You have not appended your li as a child to your ul element

Try this

function function1() {
  var ul = document.getElementById("list");
  var li = document.createElement("li");

If you need to set the id , you can do so by

li.setAttribute("id", "element4");

Which turns the function into

function function1() {
  var ul = document.getElementById("list");
  var li = document.createElement("li");
  li.setAttribute("id", "element4"); // added line

How to detect my browser version and operating system using JavaScript?

To detect operating system using JavaScript it is better to use navigator.userAgent instead of navigator.appVersion

  var OSName = "Unknown OS";_x000D_
  if (navigator.userAgent.indexOf("Win") != -1) OSName = "Windows";_x000D_
  if (navigator.userAgent.indexOf("Mac") != -1) OSName = "Macintosh";_x000D_
  if (navigator.userAgent.indexOf("Linux") != -1) OSName = "Linux";_x000D_
  if (navigator.userAgent.indexOf("Android") != -1) OSName = "Android";_x000D_
  if (navigator.userAgent.indexOf("like Mac") != -1) OSName = "iOS";_x000D_
  console.log('Your OS: ' + OSName);_x000D_

Why should text files end with a newline?

Presumably simply that some parsing code expected it to be there.

I'm not sure I would consider it a "rule", and it certainly isn't something I adhere to religiously. Most sensible code will know how to parse text (including encodings) line-by-line (any choice of line endings), with-or-without a newline on the last line.

Indeed - if you end with a new line: is there (in theory) an empty final line between the EOL and the EOF? One to ponder...

How can I restart a Java application?


public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        StringBuilder cmd = new StringBuilder();
        cmd.append(System.getProperty("java.home") + File.separator + "bin" + File.separator + "java ");
        for (String jvmArg : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
            cmd.append(jvmArg + " ");
        cmd.append("-cp ").append(ManagementFactory.getRuntimeMXBean().getClassPath()).append(" ");
        cmd.append(Main.class.getName()).append(" ");
        for (String arg : args) {
            cmd.append(arg).append(" ");

Dedicated to all those who say it is impossible.

This program collects all information available to reconstruct the original commandline. Then, it launches it and since it is the very same command, your application starts a second time. Then we exit the original program, the child program remains running (even under Linux) and does the very same thing.

WARNING: If you run this, be aware that it never ends creating new processes, similar to a fork bomb.

Passing HTML to template using Flask/Jinja2

You can also declare it HTML safe from the code:

from flask import Markup
value = Markup('<strong>The HTML String</strong>')

Then pass that value to the templates and they don't have to |safe it.

Creating a Zoom Effect on an image on hover using CSS?

  <div class="item">
  <img src="yamahdi1.jpg" alt="pepsi" width="50" height="58">
  <img src="yamahdi.jpg" alt="pepsi" width="50" height="58">
  <div class="item-overlay top"></div>


.item img {

  -moz-transition: all 0.3s;
  -webkit-transition: all 0.3s;
  transition: all 0.3s;
.item img:hover {
  -moz-transform: scale(1.1);
  -webkit-transform: scale(1.1);
  transform: scale(1.1);

Android "gps requires ACCESS_FINE_LOCATION" error, even though my manifest file contains this

CAUSE: "Beginning in Android 6.0 (API level 23), users grant permissions to apps while the app is running, not when they install the app." In this case, "ACCESS_FINE_LOCATION" is a "dangerous permission and for that reason, you get this 'java.lang.SecurityException: "gps" location provider requires ACCESS_FINE_LOCATION permission.' error (

SOLUTION: Implementing the code provided at under the "Request the permissions you need" and "Handle the permissions request response" headings.

Check whether a table contains rows or not sql server 2005

Can't you just count the rows using select count(*) from table (or an indexed column instead of * if speed is important)?

If not then maybe this article can point you in the right direction.

Java Garbage Collection Log messages

I just wanted to mention that one can get the detailed GC log with the


parameter. Then you see the PSYoungGen or PSPermGen output like in the answer.

Also -Xloggc:gc.log seems to generate the same output like -verbose:gc but you can specify an output file in the first.

Example usage:

java -Xloggc:./memory.log -XX:+PrintGCDetails Memory

To visualize the data better you can try gcviewer (a more recent version can be found on github).

Take care to write the parameters correctly, I forgot the "+" and my JBoss would not start up, without any error message!

executing a function in sql plus

As another answer already said, call select myfunc(:y) from dual; , but you might find declaring and setting a variable in sqlplus a little tricky:

sql> var y number

sql> begin
  2  select 7 into :y from dual;
  3  end;
  4  /

PL/SQL procedure successfully completed.

sql> print :y


sql> select myfunc(:y) from dual;

How to call a function after a div is ready?

You can use recursion here to do this. For example:


function checkContainer () {
  if($('#divIDer').is(':visible'))){ //if the container is visible on the page
    createGrid();  //Adds a grid to the html
  } else {
    setTimeout(checkContainer, 50); //wait 50 ms, then try again

Basically, this function will check to make sure that the element exists and is visible. If it is, it will run your createGrid() function. If not, it will wait 50ms and try again.

Note:: Ideally, you would just use the callback function of your AJAX call to know when the container was appended, but this is a brute force, standalone approach. :)


Wrong question: imposes a manichean that not exist!

You can use JSON-RPC with "less verb" (no method) and preserve the minimal standardization necessary for sendo id, parameters, error codes and warning messages. The JSON-RPC standard not say "you can't be REST", only say how to pack basic information.

"REST JSON-RPC" exists! is REST with "best practices", for minimal information packing, with simple and solid contracts.


(from this answer and didactic context)

When dealing with REST, it generally helps to start by thinking in terms of resources. In this case, the resource is not just "bank account" but it is a transaction of that bank account... But JSON-RPC not obligates the "method" parameter, all are encoded by "path" of the endpoint.

  • REST Deposit with POST /Bank/Account/John/Transaction with JSON request {"jsonrpc": "2.0", "id": 12, "params": {"currency":"USD","amount":10}}.
    The JSON response can be something as {"jsonrpc": "2.0", "result": "sucess", "id": 12}

  • REST Withdraw with POST /Bank/Account/John/Transaction ... similar.

  • ... GET /Bank/Account/John/Transaction/12345@13 ... This could return a JSON record of that exact transaction (e.g. your users generally want a record of debits and credits on their account). Something as {"jsonrpc": "2.0", "result": {"debits":[...],"credits":[...]}, "id": 13}. The convention about (REST) GET request can include encode of id by "@id", so not need to send any JSON, but still using JSON-RPC in the response pack.

Is it possible to change the location of packages for NuGet?

UPDATE for VS 2017:

Looks people in Nuget team finally started to use Nuget themselves which helped them to find and fix several important things. So now (if I'm not mistaken, as still didn't migrated to VS 2017) the below is not necessary any more. You should be able to set the "repositoryPath" to a local folder and it will work. Even you can leave it at all as by default restore location moved out of solution folders to machine level. Again - I still didn't test it by myself

VS 2015 and earlier

Just a tip to other answers (specifically this):

Location of the NuGet Package folder can be changed via configuration, but VisualStudio still reference assemblies in this folder relatively:


To workaround this (until a better solution) I used subst command to create a virtual drive which points to a new location of the Packages folder:

subst N: C:\Development\NuGet\Packages

Now when adding a new NuGet package, the project reference use its absolute location:



  1. Such a virtual drive will be deleted after restart, so make sure you handle it
  2. Don't forget to replace existing references in project files.

Use '=' or LIKE to compare strings in SQL?

In my small experience:

"=" for Exact Matches.

"LIKE" for Partial Matches.

https connection using CURL from command line

I had the same problem - I was fetching a page from my own site, which was served over HTTPS, but curl was giving the same "SSL certificate problem" message. I worked around it by adding a -k flag to the call to allow insecure connections.

curl -k

Edit: I discovered the root of the problem. I was using an SSL certificate (from StartSSL, but I don't think that matters much) and hadn't set up the intermediate certificate properly. If you're having the same problem as user1270392 above, it's probably a good idea to test your SSL cert and fix any issues with it before resorting to the curl -k fix.

Keep SSH session alive

For those wondering, @edward-coast

If you want to set the keep alive for the server, add this to /etc/ssh/sshd_config:

ClientAliveInterval 60
ClientAliveCountMax 2

ClientAliveInterval: Sets a timeout interval in seconds after which if no data has been received from the client, sshd(8) will send a message through the encrypted channel to request a response from the client.

ClientAliveCountMax: Sets the number of client alive messages (see below) which may be sent without sshd(8) receiving any messages back from the client. If this threshold is reached while client alive messages are being sent, sshd will disconnect the client, terminating the session.

How to pass parameters to $http in angularjs?

Here is how you do it:

$http.get("/url/to/resource/", {params:{"param1": val1, "param2": val2}})
    .then(function (response) { /* */ })...

Angular takes care of encoding the parameters.

Maxim Shoustin's answer does not work ({method:'GET', url:'/search', jsonData} is not a valid JavaScript literal) and JeyTheva's answer, although simple, is dangerous as it allows XSS (unsafe values are not escaped when you concatenate them).

Clearing coverage highlighting in Eclipse

I have used the Open Clover Tool for the code coverage, I have also been searching this for a long time. Its pretty straightforward, in the Coverage Explorer tab, you can find three square buttons which says the code lines you wanted to display, click on hide the coverage square box and its gone. Last button in the image below: enter image description here

Update statement with inner join on Oracle

This following syntax works for me.

(SELECT A.utl_id,
    FROM trb_pi_joint A
    JOIN trb_tpr B
    ON A.tp_id=B.tp_id Where A.pij_type=2 and a.utl_id is null
SET utl_id=utl1_id;

Convert JSON array to an HTML table in jQuery

Converting a 2D JavaScript array to an HTML table

To turn a 2D JavaScript array into an HTML table, you really need but a little bit of code :

function arrayToTable(tableData) {_x000D_
    var table = $('<table></table>');_x000D_
    $(tableData).each(function (i, rowData) {_x000D_
        var row = $('<tr></tr>');_x000D_
        $(rowData).each(function (j, cellData) {_x000D_
    return table;_x000D_
<script src=""></script>

Loading a JSON file

If you want to load your 2D array from a JSON file, you'll also need a little bit of Ajax code :

    type: "GET",
    url: "data.json",
    dataType: 'json',
    success: function (data) {

Deprecated: mysql_connect()

Its just a warning that is telling you to start using newer methods of connecting to your db such as pdo objects

The manual is here

How can I create download link in HTML?

In addition (or in replacement) to the HTML5's <a download attribute already mentioned,
the browser's download to disk behavior can also be triggered by the following http response header:

Content-Disposition: attachment; filename=ProposedFileName.txt;

This was the way to do before HTML5 (and still works with browsers supporting HTML5).

Hibernate throws org.hibernate.AnnotationException: No identifier specified for entity: com..domain.idea.MAE_MFEView


You are missing the @Id entity property, and that's why Hibernate is throwing that exception.

Entity identifiers

Any JPA entity must have an identifier property, that is marked with the Id annotation.

There are two types of identifiers:

  • assigned
  • auto-generated

Assigned identifiers

An assigned identifier looks as follows:

private Long id;

Notice that we are using a wrapper (e.g., Long, Integer) instead of a primitive type (e.g., long, int). Using a wrapper type is a better choice when using Hibernate because, by checking if the id is null or not, Hibernate can better determine if an entity is transient (it does not have an associated table row) or detached (it has an associated table row, but it's not managed by the current Persistence Context).

The assigned identifier must be set manually by the application prior to calling persist:

Post post = new Post();


Auto-generated identifiers

An auto-generated identifier requires the @GeneratedValue annotation besides the @Id:

private int id;

There are 3 strategies Hibernate can use to auto-generate the entity identifier:


The IDENTITY strategy is to be avoided if the underlying database supports sequences (e.g., Oracle, PostgreSQL, MariaDB since 10.3, SQL Server since 2012). The only major database that does not support sequences is MySQL.

The problem with IDENTITY is that automatic Hibernate batch inserts are disabled for this strategy.

The SEQUENCE strategy is the best choice unless you are using MySQL. For the SEQUENCE strategy, you also want to use the pooled optimizer to reduce the number of database roundtrips when persisting multiple entities in the same Persistence Context.

The TABLE generator is a terrible choice because it does not scale. For portability, you are better off using SEQUENCE by default and switch to IDENTITY for MySQL only.

creating Hashmap from a JSON String

You could use Jackson to do this. I have yet to find a simple Gson solution.

Where data_map.json is a JSON (object) resource file
and data_list.json is a JSON (array) resource file.

import java.util.List;
import java.util.Map;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

 * Based on:
public class JsonLoader {
    private static final ObjectMapper OBJ_MAPPER;
    private static final TypeReference<Map<String,Object>> OBJ_MAP;
    private static final TypeReference<List<Map<String,Object>>> OBJ_LIST;

    static {
        OBJ_MAPPER = new ObjectMapper();
        OBJ_MAP = new TypeReference<Map<String,Object>>(){};
        OBJ_LIST = new TypeReference<List<Map<String,Object>>>(){};

    public static void main(String[] args) {
        try {
            System.out.println(jsonToString(parseJsonString(read("data_map.json", true))));
            System.out.println(jsonToString(parseJsonString(read("data_array.json", true))));
        } catch (IOException e) {

    private static final Object parseJsonString(String jsonString) {
        try {
            if (jsonString.startsWith("{")) {
                return readJsonObject(jsonString);
            } else if (jsonString.startsWith("[")) {
                return readJsonArray(jsonString);
        } catch (JsonGenerationException e) {
        } catch (JsonMappingException e) {
        } catch (IOException e) {

        return null;

    public static String jsonToString(Object json) throws JsonProcessingException {
        return OBJ_MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(json);

    private static final Map<String,Object> readJsonObject(String jsonObjectString) throws JsonParseException, JsonMappingException, IOException {
        return OBJ_MAPPER.readValue(jsonObjectString, OBJ_MAP);

    private static final List<Map<String,Object>> readJsonArray(String jsonArrayString) throws JsonParseException, JsonMappingException, IOException {
        return OBJ_MAPPER.readValue(jsonArrayString, OBJ_LIST);

    public static final Map<String,Object> loadJsonObject(String path, boolean isResource) throws JsonParseException, JsonMappingException, MalformedURLException, IOException {
        return OBJ_MAPPER.readValue(load(path, isResource), OBJ_MAP);

    public static final List<Map<String,Object>> loadJsonArray(String path, boolean isResource) throws JsonParseException, JsonMappingException, MalformedURLException, IOException {
        return OBJ_MAPPER.readValue(load(path, isResource), OBJ_LIST);

    private static final URL pathToUrl(String path, boolean isResource) throws MalformedURLException {
        if (isResource) {
            return JsonLoader.class.getClassLoader().getResource(path);

        return new URL("file:/" + path);

    protected static File load(String path, boolean isResource) throws MalformedURLException {
        return load(pathToUrl(path, isResource));

    protected static File load(URL url) {
        try {
            return new File(url.toURI());
        } catch (URISyntaxException e) {
            return new File(url.getPath());

    public static String read(String path, boolean isResource) throws IOException {
        return read(path, "UTF-8", isResource);

    public static String read(String path, String charset, boolean isResource) throws IOException {
        return read(pathToUrl(path, isResource), charset);

    public static String read(URL url, String charset) throws IOException {
        return new Scanner(url.openStream(), charset).useDelimiter("\\A").next();


Here is the complete code for Dheeraj Sachan's example.

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Scanner;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;

public class JsonHandler {
    private static ObjectMapper propertyMapper;

    static {
        final DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        propertyMapper = new ObjectMapper();
        propertyMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        propertyMapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);

    private static class MyHashMap extends HashMap<String, List<Video>>{
        private static final long serialVersionUID = 7023107716981734468L;

    private static class Video implements Serializable {
        private static final long serialVersionUID = -446275421030765463L;

        private String dashUrl;
        private String videoBitrate;
        private String audioBitrate;
        private int videoWidth;
        private int videoHeight;
        private long fileSize;

        public String toString() {
            return "Video [url=" + dashUrl + ", video=" + videoBitrate + ", audio=" + audioBitrate
                    + ", width=" + videoWidth + ", height=" + videoHeight + ", size=" + fileSize + "]";

    public static void main(String[] args) {
        try {
            HashMap<String, List<Video>> map = loadJson("sample.json", true);
            Iterator<Entry<String, List<Video>>> lectures = map.entrySet().iterator();

            while (lectures.hasNext()) {
                Entry<String, List<Video>> lecture =;

                System.out.printf("Lecture #%s%n", lecture.getKey());

                for (Video video : lecture.getValue()) {
        } catch (IOException e) {

    public static <T> T parseUnderScoredResponse(String json, Class<T> classOfT) {
        try {
            if (json == null) {
                return null;
            return propertyMapper.readValue(json, classOfT);

        } catch (JsonParseException e) {
        } catch (JsonMappingException e) {
        } catch (IOException e) {
        return null;

    public static URL pathToUrl(String path, boolean isResource) throws MalformedURLException {
        if (isResource) {
            return JsonHandler.class.getClassLoader().getResource(path);

        return new URL("file:/" + path);

    public static File load(String path, boolean isResource) throws MalformedURLException {
        return load(pathToUrl(path, isResource));

    public static File load(URL url) {
        try {
            return new File(url.toURI());
        } catch (URISyntaxException e) {
            return new File(url.getPath());

    public static String readFile(URL url, String charset) throws IOException {
        return new Scanner(url.openStream(), charset).useDelimiter("\\A").next();

    public static String loadJsonString(String path, boolean isResource) throws IOException {
        return readFile(path, isResource, "UTF-8");

    public static String readFile(String path, boolean isResource, String charset) throws IOException {
        return readFile(pathToUrl(path, isResource), charset);

    public static HashMap<String, List<Video>> loadJson(String jsonString) throws IOException {
        return JsonHandler.parseUnderScoredResponse(jsonString, MyHashMap.class);

    public static HashMap<String, List<Video>> loadJson(String path, boolean isResource) throws IOException {
        return loadJson(loadJsonString(path, isResource));

changing color of h2

If you absolutely must use HTML to give your text color, you have to use the (deprecated) <font>-tag:

<h2><font color="#006699">Process Report</font></h2>

But otherwise, I strongly recommend you to do as rekire said: use CSS.

Excel - Sum column if condition is met by checking other column in same table

SUMIF didn't worked for me, had to use SUMIFS.


TableAmount is the table to sum the values, TableMonth the table where we search the condition and January, of course, the condition to meet.

Hope this can help someone!

Reading a string with spaces with sscanf

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


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

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

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

Full examples of using pySerial package

I have not used pyserial but based on the API documentation at it seems like a very nice interface. It might be worth double-checking the specification for AT commands of the device/radio/whatever you are dealing with.

Specifically, some require some period of silence before and/or after the AT command for it to enter into command mode. I have encountered some which do not like reads of the response without some delay first.

Stop a gif animation onload, on mouseover start the activation

Adding a suffix like this:

$('#img_gif').attr('src','file.gif?' + Math.random());  

the browser is compelled to download a new image every time the user accesses the page. Moreover the client cache may be quickly filled.

Here follows the alternative solution I tested on Chrome 49 and Firefox 45.
In the css stylesheet set the display property as 'none', like this:


Outside the '$(document).ready' statement insert:

$(window).load(function(){ $('#img_gif').show(); });

Every time the user accesses the page, the animation will be started after the complete load of all the elements. This is the only way I found to sincronize gif and html5 animations.

Please note that:
The gif animation will not restart after refreshing the page (like pressing "F5").
The "$(document).ready" statement doesn't produce the same effect of "$(window).load".
The property "visibility" doesn't produce the same effect of "display".

Unzip files programmatically in .net

From Embed Ressources:

using (Stream _pluginZipResourceStream = Assembly.GetExecutingAssembly().GetManifestResourceStream(programName + "." + ""))
    using (ZipArchive zip = new ZipArchive(_pluginZipResourceStream))

Difference Between Select and SelectMany

Select many is like cross join operation in SQL where it takes the cross product.
For example if we have

Set A={a,b,c}
Set B={x,y}

Select many can be used to get the following set

{ (x,a) , (x,b) , (x,c) , (y,a) , (y,b) , (y,c) }

Note that here we take the all the possible combinations that can be made from the elements of set A and set B.

Here is a LINQ example you can try

List<string> animals = new List<string>() { "cat", "dog", "donkey" };
List<int> number = new List<int>() { 10, 20 };

var mix = number.SelectMany(num => animals, (n, a) => new { n, a });

the mix will have following elements in flat structure like

{(10,cat), (10,dog), (10,donkey), (20,cat), (20,dog), (20,donkey)}

Installing python module within code

import os
os.system('pip install requests')

I tried above for temporary solution instead of changing docker file. Hope these might be useful to some

How do I POST an array of objects with $.ajax (jQuery or Zepto)

edit: I guess it's now starting to be safe to use the native JSON.stringify() method, supported by most browsers (yes, even IE8+ if you're wondering).

As simple as:


You should encode you data in JSON before sending it, you can't just send an object like this as POST data.

I recommand using the jQuery json plugin to do so. You can then use something like this in jQuery:

$.post(_saveDeviceUrl, {
    data : $.toJSON(postData)
}, function(response){
    //Process your response here

How to create a circle icon button in Flutter?

You can also use a RaisedButton with an image inside (for example for social login) like this (sizedbox with fittebox is needed to contraint the image on the specified size):

    fit: BoxFit.scaleDown,
    child: SizedBox(
        height: 60,
        width: 60,
        child: RaisedButton(
             child: Image.asset(
                 shape: StadiumBorder(),
                 color: Colors.white,
                     onPressed: () {},

Model summary in pytorch

While you will not get as detailed information about the model as in Keras' model.summary, simply printing the model will give you some idea about the different layers involved and their specifications.

For instance:

from torchvision import models
model = models.vgg16()

The output in this case would be something as follows:

  (features): Sequential (
    (0): Conv2d(3, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (1): ReLU (inplace)
    (2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (3): ReLU (inplace)
    (4): MaxPool2d (size=(2, 2), stride=(2, 2), dilation=(1, 1))
    (5): Conv2d(64, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (6): ReLU (inplace)
    (7): Conv2d(128, 128, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (8): ReLU (inplace)
    (9): MaxPool2d (size=(2, 2), stride=(2, 2), dilation=(1, 1))
    (10): Conv2d(128, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (11): ReLU (inplace)
    (12): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (13): ReLU (inplace)
    (14): Conv2d(256, 256, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (15): ReLU (inplace)
    (16): MaxPool2d (size=(2, 2), stride=(2, 2), dilation=(1, 1))
    (17): Conv2d(256, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (18): ReLU (inplace)
    (19): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (20): ReLU (inplace)
    (21): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (22): ReLU (inplace)
    (23): MaxPool2d (size=(2, 2), stride=(2, 2), dilation=(1, 1))
    (24): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (25): ReLU (inplace)
    (26): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (27): ReLU (inplace)
    (28): Conv2d(512, 512, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (29): ReLU (inplace)
    (30): MaxPool2d (size=(2, 2), stride=(2, 2), dilation=(1, 1))
  (classifier): Sequential (
    (0): Dropout (p = 0.5)
    (1): Linear (25088 -> 4096)
    (2): ReLU (inplace)
    (3): Dropout (p = 0.5)
    (4): Linear (4096 -> 4096)
    (5): ReLU (inplace)
    (6): Linear (4096 -> 1000)

Now you could, as mentioned by Kashyap, use the state_dict method to get the weights of the different layers. But using this listing of the layers would perhaps provide more direction is creating a helper function to get that Keras like model summary! Hope this helps!

How to wrap async function calls into a sync function in Node.js or Javascript?

Nowadays this generator pattern can be a solution in many situations.

Here an example of sequential console prompts in nodejs using async readline.question function:

var main = (function* () {

  // just import and initialize 'readline' in nodejs
  var r = require('readline')
  var rl = r.createInterface({input: process.stdin, output: process.stdout })

  // magic here, the callback is the
  var answerA = yield rl.question('do you want this? ', r=>    

  // and again, in a sync fashion
  var answerB = yield rl.question('are you sure? ', r=>        

  // readline boilerplate

  console.log(answerA, answerB)

})()  // <-- executed: iterator created from generator     // kick off the iterator, 
                // runs until the first 'yield', including rightmost code
                // and waits until another happens

What is the Python 3 equivalent of "python -m SimpleHTTPServer"

As everyone has mentioned http.server module is equivalent to python -m SimpleHTTPServer.
But as a warning from

Warning: http.server is not recommended for production. It only implements basic security checks.


http.server can also be invoked directly using the -m switch of the interpreter.

python -m http.server

The above command will run a server by default on port number 8000. You can also give the port number explicitly while running the server

python -m http.server 9000

The above command will run an HTTP server on port 9000 instead of 8000.

By default, server binds itself to all interfaces. The option -b/--bind specifies a specific address to which it should bind. Both IPv4 and IPv6 addresses are supported. For example, the following command causes the server to bind to localhost only:

python -m http.server 8000 --bind


python -m http.server 8000 -b

Python 3.8 version also supports IPv6 in the bind argument.

Directory Binding

By default, server uses the current directory. The option -d/--directory specifies a directory to which it should serve the files. For example, the following command uses a specific directory:

python -m http.server --directory /tmp/

Directory binding is introduced in python 3.7

How to convert String to long in Java?

public class StringToLong {

   public static void main (String[] args) {

      // String s = "fred";    // do this if you want an exception

      String s = "100";

      try {
         long l = Long.parseLong(s);
         System.out.println("long l = " + l);
      } catch (NumberFormatException nfe) {
         System.out.println("NumberFormatException: " + nfe.getMessage());


How to find the Vagrant IP?

I needed to know this to tell a user what to add to their host machine's host file. This works for me inside vagrant using just bash:

external_ip=$(cat /vagrant/config.yml | grep vagrant_ip | cut -d' ' -f2 | xargs)
echo -e "# Add this line to your host file:\n${external_ip}     host.vagrant.vm"

Replace words in a string - Ruby

You can try using this way :

sentence ["Robert"] = "Roger"

Then the sentence will become :

sentence = "My name is Roger" # Robert is replaced with Roger

How to create a List with a dynamic object type

Just use dynamic as the argument:

var list = new List<dynamic>();

android.view.InflateException: Binary XML file line #12: Error inflating class <unknown>

I solved this by updating my app theme to inherit from material components.

<style name="Theme.MyApp" parent="Theme.MaterialComponents.DayNight">
    <!-- ... -->

Values of disabled inputs will not be submitted

There are two attributes, namely readonly and disabled, that can make a semi-read-only input. But there is a tiny difference between them.

<input type="text" readonly />
<input type="text" disabled />
  • The readonly attribute makes your input text disabled, and users are not able to change it anymore.
  • Not only will the disabled attribute make your input-text disabled(unchangeable) but also cannot it be submitted.

jQuery approach (1):

$("#inputID").prop("readonly", true);
$("#inputID").prop("disabled", true);

jQuery approach (2):

$("#inputID").attr("disabled", "disabled");

JavaScript approach:

document.getElementById("inputID").readOnly = true;
document.getElementById("inputID").disabled = true;

PS disabled and readonly are standard html attributes. prop introduced with jQuery 1.6.

How to set up file permissions for Laravel?

We've run into many edge cases when setting up permissions for Laravel applications. We create a separate user account (deploy) for owning the Laravel application folder and executing Laravel commands from the CLI, and run the web server under www-data. One issue this causes is that the log file(s) may be owned by www-data or deploy, depending on who wrote to the log file first, obviously preventing the other user from writing to it in the future.

I've found that the only sane and secure solution is to use Linux ACLs. The goal of this solution is:

  1. To allow the user who owns/deploys the application read and write access to the Laravel application code (we use a user named deploy).
  2. To allow the www-data user read access to Laravel application code, but not write access.
  3. To prevent any other users from accessing the Laravel application code/data at all.
  4. To allow both the www-data user and the application user (deploy) write access to the storage folder, regardless of which user owns the file (so both deploy and www-data can write to the same log file for example).

We accomplish this as follows:

  1. All files within the application/ folder are created with the default umask of 0022, which results in folders having drwxr-xr-x permissions and files having -rw-r--r--.
  2. sudo chown -R deploy:deploy application/ (or simply deploy your application as the deploy user, which is what we do).
  3. chgrp www-data application/ to give the www-data group access to the application.
  4. chmod 750 application/ to allow the deploy user read/write, the www-data user read-only, and to remove all permissions to any other users.
  5. setfacl -Rdm u:www-data:rwx,u:deploy:rwx application/storage/ to set the default permissions on the storage/ folder and all subfolders. Any new folders/files created in the storage folder will inherit these permissions (rwx for both www-data and deploy).
  6. setfacl -Rm u:www-data:rwX,u:deploy:rwX application/storage/ to set the above permissions on any existing files/folders.

SQL query question: SELECT ... NOT IN

SELECT distinct idCustomer FROM reservations
WHERE DATEPART ( hour, insertDate) < 2
  and idCustomer is not null

Make sure your list parameter does not contain null values.

Here's an explanation:

WHERE field1 NOT IN (1, 2, 3, null)

is the same as:

WHERE NOT (field1 = 1 OR field1 = 2 OR field1 = 3 OR field1 = null)
  • That last comparision evaluates to null.
  • That null is OR'd with the rest of the boolean expression, yielding null. (*)
  • null is negated, yielding null.
  • null is not true - the where clause only keeps true rows, so all rows are filtered.

(*) Edit: this explanation is pretty good, but I wish to address one thing to stave off future nit-picking. (TRUE OR NULL) would evaluate to TRUE. This is relevant if field1 = 3, for example. That TRUE value would be negated to FALSE and the row would be filtered.

What is the difference between #include <filename> and #include "filename"?

Form 1 - #include < xxx >

First, looks for the presence of header file in the current directory from where directive is invoked. If not found, then it searches in the preconfigured list of standard system directories.

Form 2 - #include "xxx"

This looks for the presence of header file in the current directory from where directive is invoked.

The exact search directory list depends on the target system, how GCC is configured, and where it is installed. You can find the search directory list of your GCC compiler by running it with -v option.

You can add additional directories to the search path by using - Idir, which causes dir to be searched after the current directory (for the quote form of the directive) and ahead of the standard system directories.

Basically, the form "xxx" is nothing but search in current directory; if not found falling back the form

Regex to validate password strength

Answers given above are perfect but I suggest to use multiple smaller regex rather than a big one.
Splitting the long regex have some advantages:

  • easiness to write and read
  • easiness to debug
  • easiness to add/remove part of regex

Generally this approach keep code easily maintainable.

Having said that, I share a piece of code that I write in Swift as example:

struct RegExp {

     Check password complexity

     - parameter password:         password to test
     - parameter length:           password min length
     - parameter patternsToEscape: patterns that password must not contains
     - parameter caseSensitivty:   specify if password must conforms case sensitivity or not
     - parameter numericDigits:    specify if password must conforms contains numeric digits or not

     - returns: boolean that describes if password is valid or not
    static func checkPasswordComplexity(password password: String, length: Int, patternsToEscape: [String], caseSensitivty: Bool, numericDigits: Bool) -> Bool {
        if (password.length < length) {
            return false
        if caseSensitivty {
            let hasUpperCase = RegExp.matchesForRegexInText("[A-Z]", text: password).count > 0
            if !hasUpperCase {
                return false
            let hasLowerCase = RegExp.matchesForRegexInText("[a-z]", text: password).count > 0
            if !hasLowerCase {
                return false
        if numericDigits {
            let hasNumbers = RegExp.matchesForRegexInText("\\d", text: password).count > 0
            if !hasNumbers {
                return false
        if patternsToEscape.count > 0 {
            let passwordLowerCase = password.lowercaseString
            for pattern in patternsToEscape {
                let hasMatchesWithPattern = RegExp.matchesForRegexInText(pattern, text: passwordLowerCase).count > 0
                if hasMatchesWithPattern {
                    return false
        return true

    static func matchesForRegexInText(regex: String, text: String) -> [String] {
        do {
            let regex = try NSRegularExpression(pattern: regex, options: [])
            let nsString = text as NSString
            let results = regex.matchesInString(text,
                options: [], range: NSMakeRange(0, nsString.length))
            return { nsString.substringWithRange($0.range)}
        } catch let error as NSError {
            print("invalid regex: \(error.localizedDescription)")
            return []

What does upstream mean in nginx?

It's used for proxying requests to other servers.

An example from is:

http {
  upstream myproject {
    server weight=3;

  server {
    listen 80;
    location / {
      proxy_pass http://myproject;

This means all requests for / go to the any of the servers listed under upstream XXX, with a preference for port 8000.

JOIN two SELECT statement results

If Age and Palt are columns in the same Table, you can count(*) all tasks and sum only late ones like this:

select ks,
       count(*) tasks,
       sum(case when Age > Palt then 1 end) late
  from Table
 group by ks

CSS Border Not Working

Have you tried using Firebug to inspect the rendered HTML, and to see exactly what css is being applied to the various elements? That should pick up css errors like the ones mentioned above, and you can see what styles are being inherited and from where - it is an invaluable too in any css debugging.

How to convert TimeStamp to Date in Java?

First of all, you're not leveraging the advantage of using a PreparedStatement. I would first suggest that you modify your PreparedStatement as follows:

PreparedStatement statement = con.prepareStatement("select * from orders where status=? AND date=?")

You can then use statement.setXX(param_index, param_value) to set the respective values. For conversion to timestamp, have a look at the following javadocs:


Hope this helps!

linking problem: fatal error LNK1112: module machine type 'x64' conflicts with target machine type 'X86'

Recently,I also encountered this problem. That's because I used qt(x64) in vs win32. If you want to use qt application x64, you could choose vs x64--as the above. If you want to use win32 and perhaps you haven't,you need to download qt(32bit),then correctly set your enviroment, such as the lib directory, etc.(note: maybe you are is old set in x64(other version), if you convert your win32 or x64 into another, Additional Dependencies includes the old directory!)

Testing if a list of integer is odd or even

You could try using Linq to project the list:

var output = lst.Select(x => x % 2 == 0).ToList();

This will return a new list of bools such that {1, 2, 3, 4, 5} will map to {false, true, false, true, false}.

Getting an attribute value in xml element

How about:


import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;

public class Demo {

    public static void main(String[] args) throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document document = db.parse(new File("input.xml"));
        NodeList nodeList = document.getElementsByTagName("Item");
        for(int x=0,size= nodeList.getLength(); x<size; x++) {

Duplicate symbols for architecture x86_64 under Xcode

This occurred on me when I accepted "recommended settings" pop-up on a project that I develop two years ago in Objective-C.

The problem was that when you accepted the "recommended settings" update, Xcode automatically changed or added some build settings, including GCC_NO_COMMON_BLOCKS = YES;.

This made the build failed with the duplicate symbol error in my updated project. So I changed No Common Block to NO in my build settings and the error was gone.

Is JavaScript's "new" keyword considered harmful?

I have just read some parts of his Crockfords book "Javascript: The Good Parts". I get the feeling that he considers everything that ever has bitten him as harmful:

About switch fall through:

I never allow switch cases to fall through to the next case. I once found a bug in my code caused by an unintended fall through immediately after having made a vigorous speech about why fall through was sometimes useful. (page 97, ISBN 978-0-596-51774-8)

About ++ and --

The ++ (increment) and -- (decrement) operators have been known to contribute to bad code by encouraging exessive trickiness. They are second only to faulty architecture in enabling viruses and other security menaces. (page 122)

About new:

If you forget to include the new prefix when calling a constructor function, then this will not be bound to the new object. Sadly, this will be bound to the global object, so instead of augmenting your new object, you will be clobbering global variables. That is really bad. There is no compile warning, and there is no runtime warning. (page 49)

There are more, but I hope you get the picture.

My answer to your question: No, it's not harmful. but if you forget to use it when you should you could have some problems. If you are developing in a good environment you notice that.


About a year after this answer was written the 5th edition of ECMAScript was released, with support for strict mode. In strict mode, this is no longer bound to the global object but to undefined.

webpack is not recognized as a internal or external command,operable program or batch file

I've had same issue and just added the code block into my package.json file;

 "scripts": {
   "build": "webpack -d --progress --colors"

and then run command on terminal;

npm run build

How to set at runtime?

System.setProperty is not working for applets. Because JVM already running before applet start. In this case we use applet parameters like this:

        id: 'MyApplet',
        code: 'com.mkysoft.myapplet.SomeClass',
        archive: 'com.mkysoft.myapplet.jar'
    }, {
        java_version: "1.6*", // Target version
        cache_option: "no",
        cache_archive: "",
        codebase_lookup: true,
        java_arguments: ""
       "1.6" // Minimum version

You can find deployJava.js at

Pythonic way to print list items

[print(a) for a in list] will give a bunch of None types at the end though it prints out all the items

SQL SELECT WHERE field contains words

SELECT * FROM MyTable WHERE Column1 Like "*word*"

This will display all the records where column1 has a partial value contains word.

restrict edittext to single line

Also it's important to pay attention if the property android:inputType is textMultiLine. If so, the properties android:singleLine, android:imeOptions, android:ellipsize and android maxLines will be ignored and your EditText will accepted MultiLines anyway.

What is the fastest way to transpose a matrix in C++?

This is a good question. There are many reason you would want to actually transpose the matrix in memory rather than just swap coordinates, e.g. in matrix multiplication and Gaussian smearing.

First let me list one of the functions I use for the transpose (EDIT: please see the end of my answer where I found a much faster solution)

void transpose(float *src, float *dst, const int N, const int M) {
    #pragma omp parallel for
    for(int n = 0; n<N*M; n++) {
        int i = n/N;
        int j = n%N;
        dst[n] = src[M*j + i];

Now let's see why the transpose is useful. Consider matrix multiplication C = A*B. We could do it this way.

for(int i=0; i<N; i++) {
    for(int j=0; j<K; j++) {
        float tmp = 0;
        for(int l=0; l<M; l++) {
            tmp += A[M*i+l]*B[K*l+j];
        C[K*i + j] = tmp;

That way, however, is going to have a lot of cache misses. A much faster solution is to take the transpose of B first

for(int i=0; i<N; i++) {
    for(int j=0; j<K; j++) {
        float tmp = 0;
        for(int l=0; l<M; l++) {
            tmp += A[M*i+l]*B[K*j+l];
        C[K*i + j] = tmp;

Matrix multiplication is O(n^3) and the transpose is O(n^2), so taking the transpose should have a negligible effect on the computation time (for large n). In matrix multiplication loop tiling is even more effective than taking the transpose but that's much more complicated.

I wish I knew a faster way to do the transpose (Edit: I found a faster solution, see the end of my answer). When Haswell/AVX2 comes out in a few weeks it will have a gather function. I don't know if that will be helpful in this case but I could image gathering a column and writing out a row. Maybe it will make the transpose unnecessary.

For Gaussian smearing what you do is smear horizontally and then smear vertically. But smearing vertically has the cache problem so what you do is

Smear image horizontally
transpose output 
Smear output horizontally
transpose output

Here is a paper by Intel explaining that

Lastly, what I actually do in matrix multiplication (and in Gaussian smearing) is not take exactly the transpose but take the transpose in widths of a certain vector size (e.g. 4 or 8 for SSE/AVX). Here is the function I use

void reorder_matrix(const float* A, float* B, const int N, const int M, const int vec_size) {
    #pragma omp parallel for
    for(int n=0; n<M*N; n++) {
        int k = vec_size*(n/N/vec_size);
        int i = (n/vec_size)%N;
        int j = n%vec_size;
        B[n] = A[M*i + k + j];


I tried several function to find the fastest transpose for large matrices. In the end the fastest result is to use loop blocking with block_size=16 (Edit: I found a faster solution using SSE and loop blocking - see below). This code works for any NxM matrix (i.e. the matrix does not have to be square).

inline void transpose_scalar_block(float *A, float *B, const int lda, const int ldb, const int block_size) {
    #pragma omp parallel for
    for(int i=0; i<block_size; i++) {
        for(int j=0; j<block_size; j++) {
            B[j*ldb + i] = A[i*lda +j];

inline void transpose_block(float *A, float *B, const int n, const int m, const int lda, const int ldb, const int block_size) {
    #pragma omp parallel for
    for(int i=0; i<n; i+=block_size) {
        for(int j=0; j<m; j+=block_size) {
            transpose_scalar_block(&A[i*lda +j], &B[j*ldb + i], lda, ldb, block_size);

The values lda and ldb are the width of the matrix. These need to be multiples of the block size. To find the values and allocate the memory for e.g. a 3000x1001 matrix I do something like this

#define ROUND_UP(x, s) (((x)+((s)-1)) & -(s))
const int n = 3000;
const int m = 1001;
int lda = ROUND_UP(m, 16);
int ldb = ROUND_UP(n, 16);

float *A = (float*)_mm_malloc(sizeof(float)*lda*ldb, 64);
float *B = (float*)_mm_malloc(sizeof(float)*lda*ldb, 64);

For 3000x1001 this returns ldb = 3008 and lda = 1008


I found an even faster solution using SSE intrinsics:

inline void transpose4x4_SSE(float *A, float *B, const int lda, const int ldb) {
    __m128 row1 = _mm_load_ps(&A[0*lda]);
    __m128 row2 = _mm_load_ps(&A[1*lda]);
    __m128 row3 = _mm_load_ps(&A[2*lda]);
    __m128 row4 = _mm_load_ps(&A[3*lda]);
     _MM_TRANSPOSE4_PS(row1, row2, row3, row4);
     _mm_store_ps(&B[0*ldb], row1);
     _mm_store_ps(&B[1*ldb], row2);
     _mm_store_ps(&B[2*ldb], row3);
     _mm_store_ps(&B[3*ldb], row4);

inline void transpose_block_SSE4x4(float *A, float *B, const int n, const int m, const int lda, const int ldb ,const int block_size) {
    #pragma omp parallel for
    for(int i=0; i<n; i+=block_size) {
        for(int j=0; j<m; j+=block_size) {
            int max_i2 = i+block_size < n ? i + block_size : n;
            int max_j2 = j+block_size < m ? j + block_size : m;
            for(int i2=i; i2<max_i2; i2+=4) {
                for(int j2=j; j2<max_j2; j2+=4) {
                    transpose4x4_SSE(&A[i2*lda +j2], &B[j2*ldb + i2], lda, ldb);

The difference between bracket [ ] and double bracket [[ ]] for accessing the elements of a list or dataframe

The significant differences between the two methods are the class of the objects they return when used for extraction and whether they may accept a range of values, or just a single value during assignment.

Consider the case of data extraction on the following list:

foo <- list( str='R', vec=c(1,2,3), bool=TRUE )

Say we would like to extract the value stored by bool from foo and use it inside an if() statement. This will illustrate the differences between the return values of [] and [[]] when they are used for data extraction. The [] method returns objects of class list (or data.frame if foo was a data.frame) while the [[]] method returns objects whose class is determined by the type of their values.

So, using the [] method results in the following:

if( foo[ 'bool' ] ){ print("Hi!") }
Error in if (foo["bool"]) { : argument is not interpretable as logical

class( foo[ 'bool' ] )
[1] "list"

This is because the [] method returned a list and a list is not valid object to pass directly into an if() statement. In this case we need to use [[]] because it will return the "bare" object stored in 'bool' which will have the appropriate class:

if( foo[[ 'bool' ]] ){ print("Hi!") }
[1] "Hi!"

class( foo[[ 'bool' ]] )
[1] "logical"

The second difference is that the [] operator may be used to access a range of slots in a list or columns in a data frame while the [[]] operator is limited to accessing a single slot or column. Consider the case of value assignment using a second list, bar():

bar <- list( mat=matrix(0,nrow=2,ncol=2), rand=rnorm(1) )

Say we want to overwrite the last two slots of foo with the data contained in bar. If we try to use the [[]] operator, this is what happens:

foo[[ 2:3 ]] <- bar
Error in foo[[2:3]] <- bar : 
more elements supplied than there are to replace

This is because [[]] is limited to accessing a single element. We need to use []:

foo[ 2:3 ] <- bar
print( foo )

[1] "R"

     [,1] [,2]
[1,]    0    0
[2,]    0    0

[1] -0.6291121

Note that while the assignment was successful, the slots in foo kept their original names.

Quick Way to Implement Dictionary in C

The quickest way would be to use an already-existing implementation, like uthash.

And, if you really want to code it yourself, the algorithms from uthash can be examined and re-used. It's BSD-licensed so, other than the requirement to convey the copyright notice, you're pretty well unlimited in what you can do with it.

Under what circumstances can I call findViewById with an Options Menu / Action Bar item?

I am trying to obtain a handle on one of the views in the Action Bar

I will assume that you mean something established via android:actionLayout in your <item> element of your <menu> resource.

I have tried calling findViewById(

To retrieve the View associated with your android:actionLayout, call findItem() on the Menu to retrieve the MenuItem, then call getActionView() on the MenuItem. This can be done any time after you have inflated the menu resource.

Make div stay at bottom of page's content all the time even when there are scrollbars

if you have a fixed height footer (for example 712px) you can do this with js like so:

var bgTop = 0;
function theResize(){
    bgTop = winHeight - 712;
    document.getElementById("bg").style.marginTop = bgTop+"px";

How connect Postgres to localhost server using pgAdmin on Ubuntu?

if you open the psql console in a terminal window, by typing

$ psql

you're super user username will be shown before the =#, for example:


That will be the user name you should use for localhost.

Adding ID's to google map markers

Why not use an cache that stores each marker object and references an ID?

var markerCache= {};
var idGen= 0;

function codeAddress(addr, contentStr){
    // create marker
    // store
    markerCache[idGen++]= marker;

Edit: of course this relies on a numeric index system that doesn't offer a length property like an array. You could of course prototype the Object object and create a length, etc for just such a thing. OTOH, generating a unique ID value (MD5, etc) of each address might be the way to go.

When & why to use delegates?

Say you want to write a procedure to integrate some real-valued function f (x) over some interval [a, b]. Say we want to use the 3-Point Gaussian method to do this (any will do, of course).

Ideally we want some function that looks like:

// 'f' is the integrand we want to integrate over [a, b] with 'n' subintervals.
static double Gauss3(Integrand f, double a, double b, int n) {
  double res = 0;

  // compute result
  // ...

  return res;

So we can pass in any Integrand, f, and get its definite integral over the closed interval.

Just what type should Integrand be?

Without Delegates

Well, without delegates, we'd need some sort of interface with a single method, say eval declared as follows:

// Interface describing real-valued functions of one variable.
interface Integrand {
  double eval(double x);

Then we'd need to create a whole bunch of classes implementing this interface, as follows:

// Some function
class MyFunc1 : Integrand {
  public double eval(double x) {
    return /* some_result */ ;

// Some other function
class MyFunc2 : Integrand {
  public double eval(double x) {
    return /* some_result */ ;

// etc

Then to use them in our Gauss3 method, we need to invoke it as follows:

double res1 = Gauss3(new MyFunc1(), -1, 1, 16);
double res2 = Gauss3(new MyFunc2(), 0, Math.PI, 16);

And Gauss3 needs to do the look like the following:

static double Gauss3(Integrand f, double a, double b, int n) {
  // Use the integrand passed in:

So we need to do all that just to use our arbitrary functions in Guass3.

With Delegates

public delegate double Integrand(double x);

Now we can define some static (or not) functions adhering to that prototype:

class Program {
   public delegate double Integrand(double x);   
   // Define implementations to above delegate 
   // with similar input and output types
   static double MyFunc1(double x) { /* ... */ }
   static double MyFunc2(double x) { /* ... */ }
   // ... etc ...

   public static double Gauss3(Integrand f, ...) { 
      // Now just call the function naturally, no f.eval() stuff.
      double a = f(x); 
      // ...

   // Let's use it
   static void Main() {
     // Just pass the function in naturally (well, its reference).
     double res = Gauss3(MyFunc1, a, b, n);
     double res = Gauss3(MyFunc2, a, b, n);    

No interfaces, no clunky .eval stuff, no object instantiation, just simple function-pointer like usage, for a simple task.

Of course, delegates are more than just function pointers under the hood, but that's a separate issue (function chaining and events).

CSS media queries: max-width OR max-height

yes, using and, like:

@media screen and (max-width: 800px), 
       screen and (max-height: 600px) {

Check if input is integer type in C

First ask yourself how you would ever expect this code to NOT return an integer:

int num; 

You specified the variable as type integer, then you scanf, but only for an integer (%d).

What else could it possibly contain at this point?

Java ElasticSearch None of the configured nodes are available

Since most of the ansswers seem to be outdated here is the setting that worked for me:

  • Elasticsearch-Version: 7.2.0 (OSS) running on Docker
  • Java-Version: JDK-11

elasticsearch.yml: production node1
transport.tcp.port: 9300
cluster.initial_master_nodes: node1


client = new PreBuiltTransportClient(Settings.builder().put("", "production").build());
client.addTransportAddress(new TransportAddress(InetAddress.getByName("localhost"), 9300));

Since PreBuiltTransportClient is deprecated you should use RestHighLevelClient for Elasticsearch-Version 7.3.0:

Char array declaration and initialization in C

I think these are two really different cases. In the first case memory is allocated and initialized in compile-time. In the second - in runtime.

How do I hide the PHP explode delimiter from submitted form results?

<select name="FakeName" id="Fake-ID" aria-required="true" required>  <?php $options=nl2br(file_get_contents("employees.txt")); $options=explode("<br />",$options);  foreach ($options as $item_array) { echo "<option value='".$item_array"'>".$item_array"</option>";  } ?> </select> 

how do I print an unsigned char as hex in c++ using ostream?

I have used in this way.

    char strInput[] = "yourchardata";
char chHex[2] = "";

int nLength = strlen(strInput);
char* chResut = new char[(nLength*2) + 1];
memset(chResut, 0, (nLength*2) + 1);

for (int i = 0; i < nLength; i++)
    sprintf(chHex, "%02X", strInput[i]& 0x00FF);    
    memcpy(&(chResut[i*2]), chHex, 2);

delete chResut;
chResut = NULL;

MySQL CURRENT_TIMESTAMP on create and on update

You are using older MySql version. Update your myqsl to 5.6.5+ it will work.

How to copy Docker images from one host to another without using a repository

You may use sshfs:

$ sshfs user@ip:/<remote-path> <local-mount-path>
$ docker save <image-id> > <local-mount-path>/myImage.tar

How can I add C++11 support to Code::Blocks compiler?

Use g++ -std=c++11 -o <output_file_name> <file_to_be_compiled>

How can I copy columns from one sheet to another with VBA in Excel?

The following works fine for me in Excel 2007. It is simple, and performs a full copy (retains all formatting, etc.):

Sheets("Sheet1").Columns(1).Copy Destination:=Sheets("Sheet2").Columns(2)

"Columns" returns a Range object, and so this is utilizing the "Range.Copy" method. "Destination" is an option to this method - if not provided the default is to copy to the paste buffer. But when provided, it is an easy way to copy.

As when manually copying items in Excel, the size and geometry of the destination must support the range being copied.

Error CS2001: Source file '.cs' could not be found

In my case, I add file as Link from another project and then rename file in source project that cause problem in destination project. I delete linked file in destination and add again with new name.

Execute PHP scripts within Node.js web server

If php is in FPM mode node-phpfpm could be an option, check the documenation

How to run different python versions in cmd

I also met the case to use both python2 and python3 on my Windows machine. Here's how i resolved it:

  1. download python2x and python3x, installed them.
  2. add C:\Python35;C:\Python35\Scripts;C:\Python27;C:\Python27\Scripts to environment variable PATH.
  3. Go to C:\Python35 to rename python.exe to python3.exe, also to C:\Python27, rename python.exe to python2.exe.
  4. restart your command window.
  5. type python2, or python3 in command line to switch the version you like.

Overlapping elements in CSS

I think you could get away with using relative positioning and then set the top/left positioning of the second DIV until you have it in the position desired.

JQuery to load Javascript file dynamically

Yes, use getScript instead of document.write - it will even allow for a callback once the file loads.

You might want to check if TinyMCE is defined, though, before including it (for subsequent calls to 'Add Comment') so the code might look something like this:

$('#add_comment').click(function() {
    if(typeof TinyMCE == "undefined") {
        $.getScript('tinymce.js', function() {

Assuming you only have to call init on it once, that is. If not, you can figure it out from here :)

Regex replace (in Python) - a simpler way?

I believe that the best idea is just to capture in a group whatever you want to replace, and then replace it by using the start and end properties of the captured group.



#the pattern will contain the expression we want to replace as the first group
pat = "word1\s(.*)\sword2"   
test = "word1 will never be a word2"
repl = "replace"

import re
m =,test)

if m and m.groups() > 0:
    line = test[:m.start(1)] + repl + test[m.end(1):]
    print line
    print "the pattern didn't capture any text"

This will print: 'word1 will never be a word2'

The group to be replaced could be located in any position of the string.

How to show Alert Message like "successfully Inserted" after inserting to DB using MVC3

Personally I'd go with AJAX.

If you cannot switch to @Ajax... helpers, I suggest you to add a couple of properties in your model

public bool TriggerOnLoad { get; set; }
public string TriggerOnLoadMessage { get; set: }

Change your view to a strongly typed Model via

@using MyModel

Before returning the View, in case of successfull creation do something like

MyModel model = new MyModel();
model.TriggerOnLoad = true;
model.TriggerOnLoadMessage = "Object successfully created!";
return View ("Add", model);

then in your view, add this

   if (model.TriggerOnLoad) {
   <script type="text/javascript">

Of course inside the tag you can choose to do anything you want, event declare a jQuery ready function:

$(document).ready(function () {

Please remember to reset the Model properties upon successfully alert emission.

Another nice thing about MVC is that you can actually define an EditorTemplate for all this, and then use it in your view via:

@Html.EditorFor (m => m.TriggerOnLoadMessage)

But in case you want to build up such a thing, maybe it's better to define your own C# class:

class ClientMessageNotification {
    public bool TriggerOnLoad { get; set; }
    public string TriggerOnLoadMessage { get; set: }

and add a ClientMessageNotification property in your model. Then write EditorTemplate / DisplayTemplate for the ClientMessageNotification class and you're done. Nice, clean, and reusable.

How to draw a custom UIView that is just a circle - iPhone app

Swift 3 - custom class, easy to reuse. It uses backgroundColor set in UI builder

import UIKit

class CircleBackgroundView: UIView {

    override func layoutSubviews() {
        layer.cornerRadius = bounds.size.width / 2
        layer.masksToBounds = true


convert from Color to brush

you can use this:

new SolidBrush(color)

where color is something like this:




or ...

Built in Python hash() function

The response is absolutely no surprise: in fact

In [1]: -5768830964305142685L & 0xffffffff
Out[1]: 1934711907L

so if you want to get reliable responses on ASCII strings, just get the lower 32 bits as uint. The hash function for strings is 32-bit-safe and almost portable.

On the other side, you can't rely at all on getting the hash() of any object over which you haven't explicitly defined the __hash__ method to be invariant.

Over ASCII strings it works just because the hash is calculated on the single characters forming the string, like the following:

class string:
    def __hash__(self):
        if not self:
            return 0 # empty
        value = ord(self[0]) << 7
        for char in self:
            value = c_mul(1000003, value) ^ ord(char)
        value = value ^ len(self)
        if value == -1:
            value = -2
        return value

where the c_mul function is the "cyclic" multiplication (without overflow) as in C.

How to run server written in js with Node.js

I open a text editor, in my case I used Atom. Paste this code

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '');
console.log('Server running at');

and save as




directory. Next I open node.js commamd prompt enter

cd c:\xampp\htdocs\myproject


node helloworld.js

next I open my chrome browser and I type


and there it is.

Failed to open/create the internal network Vagrant on Windows10

I found a solution for my problem, There was a conflict in my network adapters, I simply disabled the one who appears in the error message, then started again the running command, and a new adapter has been created after many approval messages from windows.

I hope this solution could help in some cases.

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

    public async Task<string> methodName()
             return Data;


Hope this helps :)

How to expand 'select' option width after the user wants to select an option

I improved the cychan's solution, to be like that:


        display: inline;
        float: left; 
        width: 180px; 
        overflow: hidden; 
        display: inline;
        float: left;
        width: 17px;
        height: 20px;
        border:1px solid #7f9db9;
        border-left: none;
        background: url('selectArrow.png') no-repeat 1px 1px;
    .selectArrow-mousedown{background: url('selectArrow-mousedown.png') no-repeat 1px 1px;}
    .selectArrow-mouseover{background: url('selectArrow-mouseover.png') no-repeat 1px 1px;}
<script language="javascript" src="jquery-1.3.2.min.js"></script>

<script language="javascript">
        $('#w1').wrap("<div class='wrapper'></div>");
        $('.wrapper').after("<div class='selectArrow'/>");
        }, function(){


        }, function(){

    <select id="w1">
       <option value="0">AnyAnyAnyAnyAnyAnyAny</option>
       <option value="1">AnyAnyAnyAnyAnyAnyAnyAnyAnyAnyAnyAnyAnyAny</option>


The PNGs used in css classes are uploaded here...

And you still need JQuery.....

How to split a string at the first `/` (slash) and surround part of it in a `<span>`?

You should use html():


    $("#date").html('<span>'+$("#date").text().substring(0, 2) + '</span><br />'+$("#date").text().substring(3));     

How to wait until an element is present in Selenium?

WebDriverWait wait = new WebDriverWait(driver,5)

you can use this as some time before loading whole page code gets executed and throws and error. time is in second

How do I get only directories using Get-ChildItem?


dir -r | where { $_ -is [System.IO.DirectoryInfo] }

Get the correct week number of a given date

Here is an extension version and nullable version of il_guru's answer.


public static int GetIso8601WeekOfYear(this DateTime time)
    var day = CultureInfo.InvariantCulture.Calendar.GetDayOfWeek(time);
    if (day >= DayOfWeek.Monday && day <= DayOfWeek.Wednesday)
        time = time.AddDays(3);

    return CultureInfo.InvariantCulture.Calendar.GetWeekOfYear(time, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);


public static int? GetIso8601WeekOfYear(this DateTime? time)
    return time?.GetIso8601WeekOfYear();


new DateTime(2019, 03, 15).GetIso8601WeekOfYear(); //returns 11
((DateTime?) new DateTime(2019, 03, 15)).GetIso8601WeekOfYear(); //returns 11
((DateTime?) null).GetIso8601WeekOfYear(); //returns null

How to enable Ad Hoc Distributed Queries

If ad hoc updates to system catalog is "not supported", or if you get a "Msg 5808" then you will need to configure with override like this:

EXEC sp_configure 'show advanced options', 1
RECONFIGURE with override
EXEC sp_configure 'ad hoc distributed queries', 1
RECONFIGURE with override

ASP.NET: HTTP Error 500.19 – Internal Server Error 0x8007000d

I understand that this error can occur because of many different reasons. In my case it was because I uninstalled WSUS service from Server Roles and the whole IIS went down. After doing a bit of research I found that uninstalling WSUS removes a few dlls which are used to do http compression. Since those dlls were missing and the IIS was still looking for them I did a reset using the following command in CMD:

appcmd set config -section:system.webServer/httpCompression /-[name='xpress']

Bingo! The problem is sorted now. Dont forget to run it as an administrator. You might also need to do "iisreset" as well. Just in case.

Hope it helps others. Cheers

How to resolve "gpg: command not found" error during RVM installation?

On Mac OSX 10.15, Even after installing gpg, i was getting gpg2 command not found

$ brew install gnupg gnupg2
Warning: gnupg 2.2.23 is already installed and up-to-date
To reinstall 2.2.23, run `brew reinstall gnupg`

$ gpg2 --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
-bash: gpg2: command not found

Instead, this worked for me

$ gpg --keyserver hkp:// --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Zipping a file in bash fails

Run dos2unix or similar utility on it to remove the carriage returns (^M).

This message indicates that your file has dos-style lineendings:

-bash: /backup/ /bin/bash^M: bad interpreter: No such file or directory 

Utilities like dos2unix will fix it:

 dos2unix <backup.bash > 

Or, if no such utility is installed, you can accomplish the same thing with translate:

tr -d "\015\032" <backup.bash > 

As for how those characters got there in the first place, @MadPhysicist had some good comments.

Pinging servers in Python

One thing a lot of the answers miss is that (at least in Windows) the ping command returns 0 (indicating success) if it receives the reply "Destination host unreachable."

Here is my code that checks if b'TTL=' is in the response, since that is only present when the ping reached the host. Note: Most of this code is based on the other answers here.

import platform
import subprocess

def ping(ipAddr, timeout=100):
    Send a ping packet to the specified host, using the system ping command.
    Accepts ipAddr as string for the ping destination.
    Accepts timeout in ms for the ping timeout.
    Returns True if ping succeeds otherwise Returns False.
        Ping succeeds if it returns 0 and the output includes b'TTL='
    if platform.system().lower() == 'windows':
        numFlag = '-n'
        numFlag = '-c'
    completedPing =['ping', numFlag, '1', '-w', str(timeout), ipAddr],
                                   stdout=subprocess.PIPE,    # Capture standard out
                                   stderr=subprocess.STDOUT)  # Capture standard error
    # print(completedPing.stdout)
    return (completedPing.returncode == 0) and (b'TTL=' in completedPing.stdout)


Note: This captures the output instead of printing it, so if you want to see the output of ping, you'll need to print completedPing.stdout before returning.

Import JavaScript file and call functions using webpack, ES6, ReactJS

Named exports:

Let's say you create a file called utils.js, with utility functions that you want to make available for other modules (e.g. a React component). Then you would make each function a named export:

export function add(x, y) {
  return x + y

export function mutiply(x, y) {
  return x * y

Assuming that utils.js is located in the same directory as your React component, you can use its exports like this:

import { add, multiply } from './utils.js';
add(2, 3) // Can be called wherever in your component, and would return 5.

Or if you prefer, place the entire module's contents under a common namespace:

import * as utils from './utils.js'; 

Default exports:

If you on the other hand have a module that only does one thing (could be a React class, a normal function, a constant, or anything else) and want to make that thing available to others, you can use a default export. Let's say we have a file log.js, with only one function that logs out whatever argument it's called with:

export default function log(message) {

This can now be used like this:

import log from './log.js';
log('test') // Would print 'test' in the console.

You don't have to call it log when you import it, you could actually call it whatever you want:

import logToConsole from './log.js';
logToConsole('test') // Would also print 'test' in the console.


A module can have both a default export (max 1), and named exports (imported either one by one, or using * with an alias). React actually has this, consider:

import React, { Component, PropTypes } from 'react';

How to find the logs on android studio?

In ubuntu it should be under


where user_name is logged in user name and product_name could be e.g. .AndroidStudio1.5

Javascript to Select Multiple options

<script language="JavaScript" type="text/javascript">
function loopSelected()
  var txtSelectedValuesObj = document.getElementById('txtSelectedValues');
  var selectedArray = new Array();
  var selObj = document.getElementById('selSeaShells');
  var i;
  var count = 0;
  for (i=0; i<selObj.options.length; i++) {
    if (selObj.options[i].selected) {
      selectedArray[count] = selObj.options[i].value;
  txtSelectedValuesObj.value = selectedArray;
function openInNewWindow(frm)
  // open a blank window
  var aWindow ='', 'Tutorial004NewWindow',

  // set the target to the blank window = 'Tutorial004NewWindow';

  // submit
<form action="tutorial004_nw.html" method="get">
  <table border="1" cellpadding="10" cellspacing="0">
    <td valign="top">
      <input type="button" value="Submit" onclick="openInNewWindow(this.form);" />
      <input type="button" value="Loop Selected" onclick="loopSelected();" />
      <br />
      <select name="selSea" id="selSeaShells" size="5" multiple="multiple">
        <option value="val0" selected>sea zero</option>
        <option value="val1">sea one</option>
        <option value="val2">sea two</option>
        <option value="val3">sea three</option>
        <option value="val4">sea four</option>
    <td valign="top">
      <input type="text" id="txtSelectedValues" />
      selected array

How to concatenate strings of a string field in a PostgreSQL 'group by' query?

This latest announcement list snippet might be of interest if you'll be upgrading to 8.4:

Until 8.4 comes out with a super-effient native one, you can add the array_accum() function in the PostgreSQL documentation for rolling up any column into an array, which can then be used by application code, or combined with array_to_string() to format it as a list:

I'd link to the 8.4 development docs but they don't seem to list this feature yet.

How to customize a Spinner in Android

The most elegant and flexible solution I have found so far is here:

Basically, follow these steps:

  1. Create custom layout xml file for your dropdown item, let's say I will call it spinner_item.xml
  2. Create custom view class, for your dropdown Adapter. In this custom class, you need to overwrite and set your custom dropdown item layout in getView() and getDropdownView() method. My code is as below:

    public class CustomArrayAdapter extends ArrayAdapter<String>{
    private List<String> objects;
    private Context context;
    public CustomArrayAdapter(Context context, int resourceId,
         List<String> objects) {
         super(context, resourceId, objects);
         this.objects = objects;
         this.context = context;
    public View getDropDownView(int position, View convertView,
        ViewGroup parent) {
        return getCustomView(position, convertView, parent);
    public View getView(int position, View convertView, ViewGroup parent) {
      return getCustomView(position, convertView, parent);
    public View getCustomView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater=(LayoutInflater) context.getSystemService(  Context.LAYOUT_INFLATER_SERVICE );
    View row=inflater.inflate(R.layout.spinner_item, parent, false);
    TextView label=(TextView)row.findViewById(;
    if (position == 0) {//Special style for dropdown header
    return row;
  3. In your activity or fragment, make use of the custom adapter for your spinner view. Something like this:

    Spinner sp = (Spinner)findViewById(;
    ArrayAdapter<String> myAdapter = new CustomArrayAdapter(this, R.layout.spinner_item, options);

where options is the list of dropdown item string.

How do I convert a list into a string with spaces in Python?

Why don't you add a space in the items of the list itself, like :
list = ["how ", "are ", "you "]

What is the best IDE for C Development / Why use Emacs over an IDE?

I started off by using IDEs, Microsoft or not. Then, while working on QNX some long time ago, I was forced to do with a text editor + compiler/linker. Now I prefer this simple combination––a syntax highlighting editor + C compiler and linker cli + make––to any IDEs, even if environment allows for them.

The reasons are, for me:

  1. it's everywhere. If you program in C, you do have the compiler, and usually you can get yourself an editor. The first thing I do––I get myself nedit on Linux or Notepad++ on Windows. I would go with vi, but GUI editors provide for a better fonts, and that is important when you look at code all day

  2. you can program remotely, via ssh, when you need to. And it does help a lot sometimes to be able to ssh into the target and do some quick things there

  3. it keeps me close to CLI, preferably UNIX/Linux CLI. So all the commands are on my fingertips, and when I need them I don't have to go read a reference book. And UNIX CLI can do things IDEs often can't––because their developers didn't think you'd need them

  4. most importantly, it is very much like seeing the Matrix in raw code. I operate files, so I'm forced to keep them manageable. I'm finding things in my code manually, which makes me keep it simple and organized. I do Config Management explicitly, so I know when I'm synced and how. I know my Makefiles because I write them, and they only do what I tell them to

    (if you wonder if that works in "really big projects"––it does work, and the bigger the project the more performance it gains me)

  5. when people ask me to look at their code, I don't have to learn the IDE they use

How do I release memory used by a pandas dataframe?

del df will not be deleted if there are any reference to the df at the time of deletion. So you need to to delete all the references to it with del df to release the memory.

So all the instances bound to df should be deleted to trigger garbage collection.

Use objgragh to check which is holding onto the objects.