Programs & Examples On #Google maps api 3

Google Maps JavaScript API Version 3 lets you embed the functionality of Google Maps into your own website. Version 3 provides greatly improved support for mobile devices. Ask non-programming and licensing questions in the Maps API Google Group (see full description for a link)

Access Google's Traffic Data through a Web Service

In India we are using But the data is posted by the users. I dont think google will provide the data.

how to deal with google map inside of a hidden div (Updated picture)

If used inside Bootstrap v3 tabs, the following should work:

$('a[href="#tab-location"]').on('', function(e){
    var center = map.getCenter();
    google.maps.event.trigger(map, 'resize');

where tab-location is the ID of tab containing map.

Google Map API - Removing Markers

You can try this


Hope it works.

Using Google maps API v3 how do I get LatLng with a given address?

There is a pretty good example on

To shorten it up a little:

geocoder = new google.maps.Geocoder();

function codeAddress() {

    //In this case it gets the address from an element on the page, but obviously you  could just pass it to the method instead
    var address = document.getElementById( 'address' ).value;

    geocoder.geocode( { 'address' : address }, function( results, status ) {
        if( status == google.maps.GeocoderStatus.OK ) {

            //In this case it creates a marker, but you can get the lat and lng from the location.LatLng
            map.setCenter( results[0].geometry.location );
            var marker = new google.maps.Marker( {
                map     : map,
                position: results[0].geometry.location
            } );
        } else {
            alert( 'Geocode was not successful for the following reason: ' + status );
    } );

How to set zoom level in google map

For zooming your map two level then just add this small code of line map.setZoom(map.getZoom() + 2);

TypeError: window.initMap is not a function

Could be your initMap function is in a $(document).ready function. If it is then it won't work, it has to be outside of any other functions.

Get latitude and longitude automatically using php, API

I think allow_url_fopen on your apache server is disabled. you need to trun it on.

kindly change allow_url_fopen = 0 to allow_url_fopen = 1

Don't forget to restart your Apache server after changing it.

Google maps responsive resize

Move your map variable into a scope where the event listener can use it. You are creating the map inside your initialize() function and nothing else can use it when created that way.

var map; //<-- This is now available to both event listeners and the initialize() function
function initialize() {
  var mapOptions = {
   center: new google.maps.LatLng(40.5472,12.282715),
   zoom: 6,
   mapTypeId: google.maps.MapTypeId.ROADMAP
  map = new google.maps.Map(document.getElementById("map-canvas"),
google.maps.event.addDomListener(window, 'load', initialize);
google.maps.event.addDomListener(window, "resize", function() {
 var center = map.getCenter();
 google.maps.event.trigger(map, "resize");

OVER_QUERY_LIMIT in Google Maps API v3: How do I pause/delay in Javascript to slow it down?

Using "setInterval" & "clearInterval" fixes the problem:

function drawMarkers(map, markers) {
    var _this = this,
        geocoder = new google.maps.Geocoder(),

    _this.key = 0;

    _this.interval = setInterval(function() {
        _this.markerData = markers[_this.key];

        geocoder.geocode({ address: _this.markerData.address }, yourCallback(_this.markerData));


        if ( ! markers[_this.key]) {

    }, 300);

How to use SVG markers in Google Maps API v3

Things are going better, right now you can use SVG files.

        marker = new google.maps.Marker({
            position: {lat: 36.720426, lng: -4.412573},
            map: map,
            draggable: true,
            icon: "img/tree.svg"

Get LatLng from Zip Code - Google Maps API

Couldn't you just call the following replaceing the {zipcode} with the zip code or city and state{zipcode}

Google Geocoding

Here is a link with a How To Geocode using JavaScript: Geocode walk-thru. If you need the specific lat/lng numbers call or geometry.location.lng() (API for google.maps.LatLng class)

EXAMPLE to get lat/lng:

    var lat = '';
    var lng = '';
    var address = {zipcode} or {city and state};
    geocoder.geocode( { 'address': address}, function(results, status) {
      if (status == google.maps.GeocoderStatus.OK) {
         lat = results[0];
         lng = results[0].geometry.location.lng();
      } else {
        alert("Geocode was not successful for the following reason: " + status);
    alert('Latitude: ' + lat + ' Logitude: ' + lng);

Google Maps: how to get country, state/province/region, city given a lat/long value?

What you are looking for is called reverse geocoding. Google provides a server-side reverse geocoding service through the Google Geocoding API, which you should be able to use for your project.

This is how a response to the following request would look like:,-73.961452&sensor=false


  "status": "OK",
  "results": [ {
    "types": [ "street_address" ],
    "formatted_address": "275-291 Bedford Ave, Brooklyn, NY 11211, USA",
    "address_components": [ {
      "long_name": "275-291",
      "short_name": "275-291",
      "types": [ "street_number" ]
    }, {
      "long_name": "Bedford Ave",
      "short_name": "Bedford Ave",
      "types": [ "route" ]
    }, {
      "long_name": "New York",
      "short_name": "New York",
      "types": [ "locality", "political" ]
    }, {
      "long_name": "Brooklyn",
      "short_name": "Brooklyn",
      "types": [ "administrative_area_level_3", "political" ]
    }, {
      "long_name": "Kings",
      "short_name": "Kings",
      "types": [ "administrative_area_level_2", "political" ]
    }, {
      "long_name": "New York",
      "short_name": "NY",
      "types": [ "administrative_area_level_1", "political" ]
    }, {
      "long_name": "United States",
      "short_name": "US",
      "types": [ "country", "political" ]
    }, {
      "long_name": "11211",
      "short_name": "11211",
      "types": [ "postal_code" ]
    } ],
    "geometry": {
      "location": {
        "lat": 40.7142298,
        "lng": -73.9614669
      "location_type": "RANGE_INTERPOLATED",
      "viewport": {
        "southwest": {
          "lat": 40.7110822,
          "lng": -73.9646145
        "northeast": {
          "lat": 40.7173774,
          "lng": -73.9583193

  ... Additional results[] ...

You can also opt to receive the response in xml instead of json, by simply substituting json for xml in the request URI:,-73.961452&sensor=false

As far as I know, Google will also return the same name for address components, especially for high-level names like country names and city names. Nevertheless, keep in mind that while the results are very accurate for most applications, you could still find the occasional spelling mistake or ambiguous result.

Google map V3 Set Center to specific Marker

may be this will help:


all the markers info are in markersArray array and it is global. So you can access it from anywhere using window.variablename. Each marker has a unique id and you can put that id in the key of array. so you create marker like this:

window.markersArray[2] = new google.maps.Marker({
            position: new google.maps.LatLng(23.81927, 90.362349),          
            map: map,
            title: 'your info '  

Hope this will help.

Multiple markers Google Map API v3 from array of addresses and avoid OVER_QUERY_LIMIT while geocoding on pageLoad

Answer to add multiple markers.


Here's the working Example Geocoding with multiple addresses.

 <script type="text/javascript" src="">
 <script type="text/javascript">
  var delay = 100;
  var infowindow = new google.maps.InfoWindow();
  var latlng = new google.maps.LatLng(21.0000, 78.0000);
  var mapOptions = {
    zoom: 5,
    center: latlng,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  var geocoder = new google.maps.Geocoder(); 
  var map = new google.maps.Map(document.getElementById("map"), mapOptions);
  var bounds = new google.maps.LatLngBounds();

  function geocodeAddress(address, next) {
    geocoder.geocode({address:address}, function (results,status)
         if (status == google.maps.GeocoderStatus.OK) {
          var p = results[0].geometry.location;
          var lng=p.lng();
        else {
           if (status == google.maps.GeocoderStatus.OVER_QUERY_LIMIT) {
          } else {
 function createMarker(add,lat,lng) {
   var contentString = add;
   var marker = new google.maps.Marker({
     position: new google.maps.LatLng(lat,lng),
     map: map,

  google.maps.event.addListener(marker, 'click', function() {


  var locations = [
           'New Delhi, India',
           'Mumbai, India',
           'Bangaluru, Karnataka, India',
           'Hyderabad, Ahemdabad, India',
           'Gurgaon, Haryana, India',
           'Cannaught Place, New Delhi, India',
           'Bandra, Mumbai, India',
           'Nainital, Uttranchal, India',
           'Guwahati, India',
           'West Bengal, India',
           'Jammu, India',
           'Kanyakumari, India',
           'Kerala, India',
           'Himachal Pradesh, India',
           'Shillong, India',
           'Chandigarh, India',
           'Dwarka, New Delhi, India',
           'Pune, India',
           'Indore, India',
           'Orissa, India',
           'Shimla, India',
           'Gujarat, India'
  var nextAddress = 0;
  function theNext() {
    if (nextAddress < locations.length) {
      setTimeout('geocodeAddress("'+locations[nextAddress]+'",theNext)', delay);
    } else {


As we can resolve this issue with setTimeout() function.

Still we should not geocode known locations every time you load your page as said by @geocodezip

Another alternatives of these are explained very well in the following links:

How To Avoid GoogleMap Geocode Limit!

Geocode Multiple Addresses Tutorial By Mike Williams

Example by Google Developers

How to change icon on Google map marker

var marker = new google.maps.Marker({
                position: new google.maps.LatLng(23.016427,72.571156),
                map: map,
                icon: 'images/map_marker_icon.png',
                title: 'Hi..!'

apply local path on icon only

Add Marker function with Google Maps API

Below code works for me:

<script src=""></script>
    var myCenter = new google.maps.LatLng(51.528308, -0.3817765);

    function initialize() {
           var mapProp = {
        var map = new google.maps.Map(document.getElementById("googleMap"), mapProp); 

        var marker = new google.maps.Marker({
            position: myCenter,
            icon: {
                url: '/images/marker.png',
                size: new google.maps.Size(70, 86), //marker image size
                origin: new google.maps.Point(0, 0), // marker origin
                anchor: new google.maps.Point(35, 86) // X-axis value (35, half of marker width) and 86 is Y-axis value (height of the marker).


        google.maps.event.addDomListener(window, 'load', initialize);

<div id="googleMap" style="width:500px;height:380px;"></div>

Reference link

Google Geocoding API - REQUEST_DENIED

Remove the API key parameter and its value.

eg.[YOUR ADDRESS]&sensor=true

how to get all markers on google-maps-v3

For an specific cluster use: getMarkers() Gets the array of markers in the clusterer.

For all the markers in the map use: getTotalMarkers() Gets the array of markers in the clusterer.

How to limit google autocomplete results to City and Country only

<style type="text/css">_x000D_
   body {_x000D_
         font-family: sans-serif;_x000D_
         font-size: 14px;_x000D_
<title>Google Maps JavaScript API v3 Example: Places Autocomplete</title>_x000D_
<script src="" type="text/javascript"></script>_x000D_
<script type="text/javascript">_x000D_
   function initialize() {_x000D_
      var input = document.getElementById('searchTextField');_x000D_
      var options = {_x000D_
        types: ['geocode'] //this should work !_x000D_
      var autocomplete = new google.maps.places.Autocomplete(input, options);_x000D_
   google.maps.event.addDomListener(window, 'load', initialize);_x000D_
      <input id="searchTextField" type="text" size="50" placeholder="Enter a location" autocomplete="on">_x000D_

var options = {
  types: ['geocode'] //this should work !
var autocomplete = new google.maps.places.Autocomplete(input, options);

reference to other types:

Google Maps API - how to get latitude and longitude from Autocomplete without showing the map?

You can get from the same api without any additional api or url call.


<input class="wd100" id="fromInput" type="text" name="grFrom" placeholder="From" required/>


var input = document.getElementById('fromInput');
var defaultBounds = new google.maps.LatLngBounds(
    new google.maps.LatLng(-33.8902, 151.1759),
    new google.maps.LatLng(-33.8474, 1512631)

var options = {
bounds: defaultBounds   

var autocomplete = new google.maps.places.Autocomplete(input, options);
var searchBox = new google.maps.places.SearchBox(input, {
         bounds: defaultBounds

google.maps.event.addListener(searchBox, 'places_changed', function() {
    var places = searchBox.getPlaces();

console.log(places[0].geometry.location.G); // Get Latitude
console.log(places[0].geometry.location.K); // Get Longitude

//Additional information
console.log(places[0].formatted_address); // Formated Address of Place
console.log(places[0].name); // Name of Place

    if (places.length == 0) {

    var bounds = new google.maps.LatLngBounds();

Google Maps API v3: How do I dynamically change the marker icon?

This thread might be dead, but StyledMarker is available for API v3. Just bind the color change you want to the correct DOM event using the addDomListener() method. This example is pretty close to what you want to do. If you look at the page source, change:

google.maps.event.addDomListener(document.getElementById("changeButton"),"click",function() {

to something like:

google.maps.event.addDomListener("mouseover",function() {

That should be enough to get you moving along.

The Wikipedia page on DOM Events will also help you target the event that you want to capture on the client-side.

Good luck (if you still need it)

Google Maps Api v3 - find nearest markers

I'd like to expand on Leor's suggestion for anyone confused on how to compute the nearest location and actually provide a working solution:

I'm using markers in a markers array e.g. var markers = [];.

Then let's have our position as something like var location = new google.maps.LatLng(51.99, -0.74);

Then we simply reduce our markers against the location we have like so:

markers.reduce(function (prev, curr) {

    var cpos = google.maps.geometry.spherical.computeDistanceBetween(location.position, curr.position);
    var ppos = google.maps.geometry.spherical.computeDistanceBetween(location.position, prev.position);

    return cpos < ppos ? curr : prev;


What pops out is your closest marker LatLng object.

Google Maps API 3 - Custom marker color for default (dot) marker

Combine a symbol-based marker whose path draws the outline, with a '?' character for the center. You can substitute the dot with other text ('A', 'B', etc.) as desired.

This function returns options for a marker with the a given text (if any), text color, and fill color. It uses the text color for the outline.

function createSymbolMarkerOptions(text, textColor, fillColor) {
    return {
        icon: {
            path: 'M 0,0 C -2,-20 -10,-22 -10,-30 A 10,10 0 1,1 10,-30 C 10,-22 2,-20 0,0 z',
            fillColor: fillColor,
            fillOpacity: 1,
            strokeColor: textColor,
            strokeWeight: 1.8,
            labelOrigin: { x: 0, y: -30 }
        label: {
            text: text || '?',
            color: textColor

How to fix Uncaught InvalidValueError: setPosition: not a LatLng or LatLngLiteral: in property lat: not a number?

Using angular-google-maps

$scope.bounds = new google.maps.LatLngBounds();
for (var i = $scope.markers.length - 1; i >= 0; i--) {
    $scope.bounds.extend(new google.maps.LatLng($scope.markers[i].coords.latitude, $scope.markers[i].coords.longitude));

How to disable mouse scroll wheel scaling with Google Maps API

You just need to add in map options:

scrollwheel: false

Google Maps V3 marker with label

Support for single character marker labels was added to Google Maps in version 3.21 (Aug 2015). See the new marker label API.

You can now create your label marker like this:

var marker = new google.maps.Marker({
  position: new google.maps.LatLng(result.latitude, result.longitude), 
  icon: markerIcon,
  label: {
    text: 'A'

If you would like to see the 1 character restriction removed, please vote for this issue.

Update October 2016:

This issue was fixed and as of version 3.26.10, Google Maps natively supports multiple character labels in combination with custom icons using MarkerLabels.

Google Maps: Set Center, Set Center Point and Set more points

Try using this code for v3:

gMap = new google.maps.Map(document.getElementById('map')); 
gMap.setZoom(13);      // This will trigger a zoom_changed on the map
gMap.setCenter(new google.maps.LatLng(37.4419, -122.1419));

Google Maps V3 - How to calculate the zoom level for a given bounds

map.getBounds() is not momentary operation, so I use in similar case event handler. Here is my example in Coffeescript

google.maps.event.addListenerOnce @map, 'bounds_changed', =>
  @map.setZoom(12) if @map.getZoom() > 12

Auto-center map with multiple markers in Google Maps API v3

This work for me in Angular 9:

  import {GoogleMap, GoogleMapsModule} from "@angular/google-maps";
  @ViewChild('Map') Map: GoogleMap; /* Element Map */

  locations = [
   { lat: 7.423568, lng: 80.462287 },
   { lat: 7.532321, lng: 81.021187 },
   { lat: 6.117010, lng: 80.126269 }

  constructor() {
   var bounds = new google.maps.LatLngBounds();
    setTimeout(() => {
     for (let u in this.locations) {
      var marker = new google.maps.Marker({
       position: new google.maps.LatLng(this.locations[u].lat, 

    }, 200)

And it automatically centers the map according to the indicated positions.


enter image description here

Google Maps shows "For development purposes only"

For me, Error has been fixed when activated Billing in google console. (I got 1-year developer trial)

Google Maps API: open url by clicking on marker

url isn't an object on the Marker class. But there's nothing stopping you adding that as a property to that class. I'm guessing whatever example you were looking at did that too. Do you want a different URL for each marker? What happens when you do:

for (var i = 0; i < locations.length; i++) 
    var flag = new google.maps.MarkerImage('markers/' + (i + 1) + '.png',
      new google.maps.Size(17, 19),
      new google.maps.Point(0,0),
      new google.maps.Point(0, 19));
    var place = locations[i];
    var myLatLng = new google.maps.LatLng(place[1], place[2]);
    var marker = new google.maps.Marker({
        position: myLatLng,
        map: map,
        icon: flag,
        shape: shape,
        title: place[0],
        zIndex: place[3],
        url: "/your/url/"

    google.maps.event.addListener(marker, 'click', function() {
        window.location.href = this.url;

Best way to overlay an ESRI shapefile on google maps?

I like using (open source and gui friendly) Quantum GIS to convert the shapefile to kml.

Google Maps API supports only a subset of the KML standard. One limitation is file size.

To reduce your file size, you can Quantum GIS's "simplify geometries" function. This "smooths" polygons.

Then you can select your layer and do a "save as kml" on it.

If you need to process a bunch of files, the process can be batched with Quantum GIS's ogr2ogr command from osgeo4w shell.

Finally, I recommend zipping your kml (with your favorite compression program) for reduced file size and saving it as kmz.

Google Maps: Auto close open InfoWindows?

//assuming you have a map called 'map'
var infowindow = new google.maps.InfoWindow();

var latlng1 = new google.maps.LatLng(0,0);
var marker1 = new google.maps.Marker({position:latlng1, map:map});
google.maps.event.addListener(marker1, 'click',
        infowindow.close();//hide the infowindow
        infowindow.setContent('Marker #1');//update the content for this marker, marker1);//"move" the info window to the clicked marker and open it
var latlng2 = new google.maps.LatLng(10,10);
var marker2 = new google.maps.Marker({position:latlng2, map:map});
google.maps.event.addListener(marker2, 'click',
        infowindow.close();//hide the infowindow
        infowindow.setContent('Marker #2');//update the content for this marker, marker2);//"move" the info window to the clicked marker and open it

This will "move" the info window around to each clicked marker, in effect closing itself, then reopening (and panning to fit the viewport) in its new location. It changes its contents before opening to give the desired effect. Works for n markers.

Google Maps API V3 : How show the direction from a point A to point B (Blue line)?

I'm using a popup to show the map in a new window. I'm using the following url,LONGITUDE

HTML snippet

<a target='_blank' href='${location.latitude},${location.longitude}'>Calculate route</a>

Google Maps JavaScript API RefererNotAllowedMapError* has worked for me after days and days of trying.

Add marker to Google Map on Click

In 2017, the solution is:

map.addListener('click', function(e) {
    placeMarker(e.latLng, map);

function placeMarker(position, map) {
    var marker = new google.maps.Marker({
        position: position,
        map: map

Google maps API V3 - multiple markers on exact same spot

For situations where there are multiple services in the same building you could offset the markers just a little, (say by .001 degree), in a radius from the actual point. This should also produce a nice visual effect.

Google Maps how to Show city or an Area outline

use this code:

<iframe width="600" height="450" frameborder="0" style="border:0" src="" allowfullscreen></iframe>

Google Maps API warning: NoApiKeys

Google maps requires an API key for new projects since june 2016. For more information take a look at the Google Developers Blog. Also more information in german you'll find at this blog post from the clickstorm Blog.

Google Maps API v3: Can I setZoom after fitBounds?

I don't like to suggest it, but if you must try - first call


Then create a new Thread/AsyncTask, have it sleep for 20-50ms or so and then call

gmap.setZoom( Math.max(6, gmap.getZoom()) );

from the UI thread (use a handler or the onPostExecute method for AsyncTask).

I don't know if it works, just a suggestion. Other than that you'd have to somehow calculate the zoom level from your points yourself, check if it's too low, correct it and then just call gmap.setZoom(correctedZoom)

Google maps Places API V3 autocomplete - select first option on enter

It seems there is a much better and clean solution: To use google.maps.places.SearchBox instead of google.maps.places.Autocomplete. A code is almost the same, just getting the first from multiple places. On pressing the Enter the the correct list is returned - so it runs out of the box and there is no need for hacks.

See the example HTML page:

The relevant code snippet is:

var searchBox = new google.maps.places.SearchBox(document.getElementById('searchinput'));

google.maps.event.addListener(searchBox, 'places_changed', function() {
  var place = searchBox.getPlaces()[0];

  if (!place.geometry) return;

  if (place.geometry.viewport) {
  } else {

The complete source code of the example is at:

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

My fail was to use


as an option, rather than the correct option


How to use google maps without api key

Note : This answer is now out-of-date. You are now required to have an API key to use google maps. Read More

you need to change your API from V2 to V3, Since Google Map Version 3 don't required API Key

Check this out..

write your script as

<script type="text/javascript" src=""></script>

Calculate distance between two points in google maps V3

Example using GPS latitude/longitude of 2 points.

var latitude1 = 39.46;
var longitude1 = -0.36;
var latitude2 = 40.40;
var longitude2 = -3.68;

var distance = google.maps.geometry.spherical.computeDistanceBetween(new google.maps.LatLng(latitude1, longitude1), new google.maps.LatLng(latitude2, longitude2));       

Google Map API v3 ~ Simply Close an infowindow?,null);

will close opened infowindow. It will work same as

Googlemaps API Key for Localhost

  1. Go to this address:
  2. Create new project and Create Credentials (API key)
  3. Click on "Library"
  4. Click on any API that you want
  5. Click on "Enable"
  6. Click on "Credentials" > "Edit Key"
  7. Under "Application restrictions", select "HTTP referrers (web sites)"
  8. Under "Website restrictions", Click on "ADD AN ITEM"
  9. Type your website address (or "localhost", "", "localhost:port" etc for local tests) in the text field and press ENTER to add it to the list
  10. SAVE and Use your key in your project

How to add Google Maps Autocomplete search box?

Use Google Maps JavaScript API with places library to implement Google Maps Autocomplete search box in the webpage.


<input id="searchInput" class="controls" type="text" placeholder="Enter a location">


function initMap() {
    var input = document.getElementById('searchInput');
    var autocomplete = new google.maps.places.Autocomplete(input);

Complete guide, source code, and live demo can be found from here - Google Maps Autocomplete Search Box with Map and Info Window

Google Maps API v3 marker with label

In order to add a label to the map you need to create a custom overlay. The sample at uses a custom class, Layer, that inherits from OverlayView (which inherits from MVCObject) from the Google Maps API. He has a revised version (adds support for visibility, zIndex and a click event) which can be found here:

The following code is taken directly from Marc Ridey's Blog (the revised link above).

Layer class

// Define the overlay, derived from google.maps.OverlayView
function Label(opt_options) {
  // Initialization

  // Label specific
  var span = this.span_ = document.createElement('span'); = 'position: relative; left: -50%; top: -8px; ' +
  'white-space: nowrap; border: 1px solid blue; ' +
  'padding: 2px; background-color: white';

  var div = this.div_ = document.createElement('div');
  div.appendChild(span); = 'position: absolute; display: none';
Label.prototype = new google.maps.OverlayView;

// Implement onAdd
Label.prototype.onAdd = function() {
  var pane = this.getPanes().overlayImage;

  // Ensures the label is redrawn if the text or position is changed.
  var me = this;
  this.listeners_ = [
    google.maps.event.addListener(this, 'position_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'visible_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'clickable_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'text_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'zindex_changed', function() { me.draw(); }),
    google.maps.event.addDomListener(this.div_, 'click', function() {
      if (me.get('clickable')) {
        google.maps.event.trigger(me, 'click');

// Implement onRemove
Label.prototype.onRemove = function() {

 // Label is removed from the map, stop updating its position/text.
 for (var i = 0, I = this.listeners_.length; i < I; ++i) {

// Implement draw
Label.prototype.draw = function() {
 var projection = this.getProjection();
 var position = projection.fromLatLngToDivPixel(this.get('position'));

 var div = this.div_; = position.x + 'px'; = position.y + 'px'; = 'block';

 this.span_.innerHTML = this.get('text').toString();


    <meta http-equiv="content-type" content="text/html; charset=utf-8">
      Label Overlay Example
    <script type="text/javascript" src=""></script>
    <script type="text/javascript" src="label.js"></script>
    <script type="text/javascript">
      var marker;

      function initialize() {
        var latLng = new google.maps.LatLng(40, -100);

        var map = new google.maps.Map(document.getElementById('map_canvas'), {
          zoom: 5,
          center: latLng,
          mapTypeId: google.maps.MapTypeId.ROADMAP

        marker = new google.maps.Marker({
          position: latLng,
          draggable: true,
          zIndex: 1,
          map: map,
          optimized: false

        var label = new Label({
          map: map
        label.bindTo('position', marker);
        label.bindTo('text', marker, 'position');
        label.bindTo('visible', marker);
        label.bindTo('clickable', marker);
        label.bindTo('zIndex', marker);

        google.maps.event.addListener(marker, 'click', function() { alert('Marker has been clicked'); })
        google.maps.event.addListener(label, 'click', function() { alert('Label has been clicked'); })

      function showHideMarker() {

      function pinUnpinMarker() {
        var draggable = marker.getDraggable();
  <body onload="initialize()">
    <div id="map_canvas" style="height: 200px; width: 200px"></div>
    <button type="button" onclick="showHideMarker();">Show/Hide Marker</button>
    <button type="button" onclick="pinUnpinMarker();">Pin/Unpin Marker</button>

Google Maps API throws "Uncaught ReferenceError: google is not defined" only when using AJAX

I know this answer is not directly related to this questions' issue but in some cases the "Uncaught ReferenceError: google is not defined" issue will occur if your js file is being called prior to the google maps api you're DON'T DO this:

<script type ="text/javascript" src ="SomeJScriptfile.js"></script>
<script type="text/javascript" src=""></script>

Google Maps API v3: How to remove all markers?

I have just tried this with kmlLayer.setMap(null) and it worked. Not sure if that would work with regular markers but appears to work correctly.

ERROR: Google Maps API error: MissingKeyMapError

Yes. Now Google wants an API key to authenticate users to access their APIs`.

You can get the API key from the following link. Go through the link and you need to enter a project and so on. But it is easy. Hassle free.

Once you get the API key change the previous

<script src=""></script>


<script src=""></script>

Now your google map is in action. In case if you are wondering to get the longitude and latitude to input to Maps. Just pin the location you want and check the URL of the browser. You can see longitude and latitude values there. Just copy those values and paste it as follows.

new google.maps.LatLng(longitude ,latitude )

How to Display Multiple Google Maps per page with API V3

OP wanted two specific maps, but if you'd like to have a dynamic number of maps on one page (for instance a list of retailer locations) you need to go another route. The standard implementation of Google maps API defines the map as a global variable, this won't work with a dynamic number of maps. Here's my code to solve this without global variables:

function mapAddress(mapElement, address) {
var geocoder = new google.maps.Geocoder();

geocoder.geocode({ 'address': address }, function (results, status) {
    if (status == google.maps.GeocoderStatus.OK) {
        var mapOptions = {
            zoom: 14,
            center: results[0].geometry.location,
            disableDefaultUI: true
        var map = new google.maps.Map(document.getElementById(mapElement), mapOptions);
        var marker = new google.maps.Marker({
            map: map,
            position: results[0].geometry.location
    } else {
        alert("Geocode was not successful for the following reason: " + status);

Just pass the ID and address of each map to the function to plot the map and mark the address.

google maps v3 marker info window on mouseover

Thanks to duncan answer, I end up with this:

marker.addListener('mouseover', () =>, marker))
marker.addListener('mouseout', () => infoWindow.close())

Google Maps API v3 adding an InfoWindow to each marker

In My case (Using Javascript insidde Razor) This worked perfectly inside an Foreach loop

google.maps.event.addListener(marker, 'click', function() {, this);

Google Maps v3 - limit viewable area and zoom level

To limit the zoom on v.3+. in your map setting add default zoom level and minZoom or maxZoom (or both if required) zoom levels are 0 to 19. You must declare deafult zoom level if limitation is required. all are case sensitive!

function initialize() {
   var mapOptions = {

Google Maps JS API v3 - Simple Multiple Marker Example

  • I know this answer is very much late. But I wish this will help other developers also. :-)
  • The Following code will add multiple markers on the google map with the information window.
  • And this code can be used to plot any number of markers on the map.
  • Please put your Google Map API key to the correct position of this code. (I have marked that as "Your API Key")

<!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>My Google Map</title>
            height: 600px;
            width: 100%;

<h1>My Google Map`</h1>
<div id="map"></div>

        function initMap(){
          //Map options
            var options = {
                center:{lat:42.3601, lng:-71.0589}
            // new map
            var map = new google.maps.Map(document.getElementById('map'), options);
            // customer marker
            var iconBase = '';
            //array of Marrkeers
            var markers = [
                coords:{lat: 42.4668, lng: -70.9495},img:iconBase,con:'<h3> This Is your Content <h3>'
                coords:{lat: 42.8584, lng: -70.9300},img:iconBase,con:'<h3> This Is your Content <h3>'
                coords:{lat: 42.7762, lng: -71.0773},img:iconBase,con:'<h3> This Is your Content <h3>'

            //loopthrough markers
            for(var i = 0; i <markers.length; i++){
              //add markeers

            //function for the plotting markers on the map
            function addMarker (props){
              var marker = new google.maps.Marker({
                position: props.coords,
              var infoWindow = new google.maps.InfoWindow({
              marker.addListener("click", () => {
      , marker);



Google MAP API v3: Center & Zoom on displayed markers

for center and auto zoom on display markers

// map: an instance of google.maps.Map object

// latlng_points_array: an array of google.maps.LatLng objects

var latlngbounds = new google.maps.LatLngBounds( );

    for ( var i = 0; i < latlng_points_array.length; i++ ) {
        latlngbounds.extend( latlng_points_array[i] );

map.fitBounds( latlngbounds );

Get restaurants near my location

Is this what you are looking for?,-123.137784&radius=500&sensor=false&key=*PlacesAPIKey*&types=restaurant

types is optional

Close all infowindows in Google Maps API v3

You should have to click your map - $('#map-selector').click();

Google Maps API Multiple Markers with Infowindows

If you also want to bind closing of infowindow to some event, try something like this

google.maps.event.addListener(marker,'click', (function(marker,content,infowindow){ 
    return function() {
        google.maps.event.addListener(map,'click', function(){ 

Google maps API V3 method fitBounds()

LatLngBounds must be defined with points in (south-west, north-east) order. Your points are not in that order.

The general fix, especially if you don't know the points will definitely be in that order, is to extend an empty bounds:

var bounds = new google.maps.LatLngBounds();

The API will sort out the bounds.

Google maps Marker Label with multiple characters

First of all, Thanks to code author!

I found the below link while googling and it is very simple and works best. Would never fail unless SVG is deprecated.

There is some js loading error in the code here but its perfectly working on the link provided.

var mapOptions = {_x000D_
    zoom: 16,_x000D_
    center: new google.maps.LatLng(-37.808846, 144.963435)_x000D_
  map = new google.maps.Map(document.getElementById('map-canvas'),_x000D_
var pinz = [_x000D_
            'lat' : -37.807817,_x000D_
            'lon' : 144.958377_x000D_
        'lable' : 2_x000D_
            'lat' : -37.807885,_x000D_
            'lon' : 144.965415_x000D_
        'lable' : 42_x000D_
            'lat' : -37.811377,_x000D_
            'lon' : 144.956596_x000D_
        'lable' : 87_x000D_
            'lat' : -37.811293,_x000D_
            'lon' : 144.962883_x000D_
        'lable' : 145_x000D_
            'lat' : -37.808089,_x000D_
            'lon' : 144.962089_x000D_
        'lable' : 999_x000D_
for(var i = 0; i <= pinz.length; i++){_x000D_
   var image = 'data:image/svg+xml,' + pinz[i].lable + '%3C%2Ftext%3E%3C%2Fsvg%3E';_x000D_
   var myLatLng = new google.maps.LatLng(pinz[i], pinz[i].location.lon);_x000D_
   var marker = new google.maps.Marker({_x000D_
      position: myLatLng,_x000D_
      map: map,_x000D_
      icon: image_x000D_
html, body, #map-canvas {_x000D_
  height: 100%;_x000D_
  margin: 0px;_x000D_
  padding: 0px_x000D_
<div id="map-canvas"></div>_x000D_
<script async defer src=",places"></script>

You just need to uri-encode your SVG html and replace the one in the image variable after "data:image/svg+xml" in the for loop.

For uri encoding you can use uri-encoder-decoder

You can decode the existing svg code first to get a better understanding of what is written.

How can I create numbered map markers in Google Maps V3?

Google Maps version 3 has built-in support for marker labels. No need to generate your own images anymore or implement 3rd party classes. Marker Labels

Correct redirect URI for Google API and OAuth 2.0

There's no problem with using a localhost url for Dev work - obviously it needs to be changed when it comes to production.

You need to go here: and then follow the link for the API Console - link's in the Basic Steps section. When you've filled out the new application form you'll be asked to provide a redirect Url. Put in the page you want to go to once access has been granted.

When forming the Google oAuth Url - you need to include the redirect url - it has to be an exact match or you'll have problems. It also needs to be UrlEncoded.

What's the point of 'meta viewport user-scalable=no' in the Google Maps API

Disabling user-scalable (namely, the ability to double tap to zoom) allows the browser to reduce the click delay. In touch-enable browsers, when the user expects the double tap to zoom, the browser generally waits 300ms before firing the click event, waiting to see if the user will double tap. Disabling user-scalable allows for the Chrome browser to fire the click event immediately, allowing for a better user experience.

From Google IO 2013 session

Update: its not true anymore, <meta name="viewport" content="width=device-width"> is enough to remove 300ms delay

Map isn't showing on Google Maps JavaScript API v3 when nested in a div tag

I solved this problem with:

    <div id="map" style="width: 100%; height: 100%; position: absolute;">
                 <div id="map-canvas"></div>

How to move a marker in Google Maps API

        position: fixed;
        top: 5%;
        background-color: #fff;
        border-radius: 5px;
        box-shadow: 0 0 6px #B2B2B2;
        display: inline-block;
        padding: 8px 8px;
        width: 98%;
        height: 92%;
        display: none;
        z-index: 1000;
        position: fixed;
        display: inline-block;
        width: 99%;
        height: 93%;
        display: none;
        z-index: 1000;

        position: fixed;
        top: 50%;
        left: 50%;
        opacity: 1!important;
        margin-top: -100px;
        margin-left: -150px;
        background-color: #fff;
        border-radius: 5px;
        box-shadow: 0 0 6px #B2B2B2;
        display: inline-block;
        padding: 8px 8px;
        max-width: 66%;
        display: none;
        color: #000;

        color: #FFF;
        background-image: linear-gradient(to bottom,#d67631,#d67631);
        //  border-color: rgba(47, 164, 35, 1);
        width: 100%;
        cursor: move;
        display: block;
        right: -10px;
        height: 20px;
        cursor: pointer;
        cursor: pointer !important;

<div id="loading">
    <i class="fa fa-circle-o-notch fa-spin fa-2x"></i>
<div id="frame">
    <div id="headerx"></div>
    <div id="map" >    

$url = Yii::app()->baseUrl . '/reports/reports/transponderdetails';
<script src=""></script>

    function clode() {
    function track(id) {
        $('#loading').parent().css("opacity", '0.7');

            type: "POST",
            url: '<?php echo $url; ?>',
            data: {'id': id},
            success: function(data) {
                $('#loading').parents().css("opacity", '1');
                var thelat = parseFloat($('#lat').text());
                var long = parseFloat($('#long').text());
                var lat = thelat;
                var lng = long;
                var orlat=thelat;
                var orlong=long;
                //Intialize the Path Array
                var path = new google.maps.MVCArray();
                var service = new google.maps.DirectionsService();

                var myLatLng = new google.maps.LatLng(lat, lng), myOptions = {zoom: 4, center: myLatLng, mapTypeId: google.maps.MapTypeId.ROADMAP};
                var map = new google.maps.Map(document.getElementById('map'), myOptions);
                var poly = new google.maps.Polyline({map: map, strokeColor: '#4986E7'});
                var marker = new google.maps.Marker({position: myLatLng, map: map});

                function initialize() {
                    movepointer(map, marker);
                    var drawingManager = new google.maps.drawing.DrawingManager();

                function movepointer(map, marker) {
                    marker.setPosition(new google.maps.LatLng(lat, lng));
                    map.panTo(new google.maps.LatLng(lat, lng));

                    var src = myLatLng;//start point
                    var des = myLatLng;// should be the destination
                        origin: src,
                        destination: des,
                        travelMode: google.maps.DirectionsTravelMode.DRIVING
                    }, function(result, status) {
                        if (status == google.maps.DirectionsStatus.OK) {
                            for (var i = 0, len = result.routes[0].overview_path.length; i < len; i++) {


                // function()
                setInterval(function() {
                    lat = Math.random() + orlat;
                    lng = Math.random() + orlong;
                    console.log(lat + "-" + lng);
                    myLatLng = new google.maps.LatLng(lat, lng);
                    movepointer(map, marker);

                }, 1000);

            error: function() {
                $('#frame').html('Sorry, no details found');
        return false;
    $(function() {


Google Map API v3 — set bounds and center

Yes, you can declare your new bounds object.

 var bounds = new google.maps.LatLngBounds();

Then for each marker, extend your bounds object:


API: google.maps.LatLngBounds

How to trigger the onclick event of a marker on a Google Maps V3?

I've found out the solution! Thanks to Firebug ;)

//"markers" is an array that I declared which contains all the marker of the map
//"i" is the index of the marker in the array that I want to trigger the OnClick event

//V2 version is:
GEvent.trigger(markers[i], 'click');

//V3 version is:
google.maps.event.trigger(markers[i], 'click');

Google Maps API OVER QUERY LIMIT per second limit

The geocoder has quota and rate limits. From experience, you can geocode ~10 locations without hitting the query limit (the actual number probably depends on server loading). The best solution is to delay when you get OVER_QUERY_LIMIT errors, then retry. See these similar posts:

This API project is not authorized to use this API. Please ensure that this API is activated in the APIs Console

I experienced the same issue on a Drupal site. After enabling the Geocoding API on the Google Cloud Platform, works for me. On my setup I require two APIs, Geocoding and Maps Javascript APIs.

How do you create a Marker with a custom icon for google maps API v3?

Symbol You Want on Color You Want!

I was looking for this answer for days and here it is the right and easy way to create a custom marker:

'' where xxx is the text and 5680fc is the hexadecimal color code of the background and 000000 is the hexadecimal color code of the text.

Theses markers are totally dynamic and you can create whatever balloon icon you want. Just change the URL.

Change marker size in Google maps V3

This answer expounds on John Black's helpful answer, so I will repeat some of his answer content in my answer.

The easiest way to resize a marker seems to be leaving argument 2, 3, and 4 null and scaling the size in argument 5.

var pinIcon = new google.maps.MarkerImage(
    null, /* size is determined at runtime */
    null, /* origin is 0,0 */
    null, /* anchor is bottom center of the scaled image */
    new google.maps.Size(42, 68)

As an aside, this answer to a similar question asserts that defining marker size in the 2nd argument is better than scaling in the 5th argument. I don't know if this is true.

Leaving arguments 2-4 null works great for the default google pin image, but you must set an anchor explicitly for the default google pin shadow image, or it will look like this:

what happens when you leave anchor null on an enlarged shadow

The bottom center of the pin image happens to be collocated with the tip of the pin when you view the graphic on the map. This is important, because the marker's position property (marker's LatLng position on the map) will automatically be collocated with the visual tip of the pin when you leave the anchor (4th argument) null. In other words, leaving the anchor null ensures the tip points where it is supposed to point.

However, the tip of the shadow is not located at the bottom center. So you need to set the 4th argument explicitly to offset the tip of the pin shadow so the shadow's tip will be colocated with the pin image's tip.

By experimenting I found the tip of the shadow should be set like this: x is 1/3 of size and y is 100% of size.

var pinShadow = new google.maps.MarkerImage(
    /* Offset x axis 33% of overall size, Offset y axis 100% of overall size */
    new google.maps.Point(40, 110), 
    new google.maps.Size(120, 110)); 

to give this:

offset the enlarged shadow anchor explicitly

Center/Set Zoom of Map to cover all visible Markers?

You need to use the fitBounds() method.

var markers = [];//some array
var bounds = new google.maps.LatLngBounds();
for (var i = 0; i < markers.length; i++) {


Documentation from

fitBounds(bounds[, padding])


`bounds`:  [`LatLngBounds`][1]|[`LatLngBoundsLiteral`][1]
`padding` (optional):  number|[`Padding`][1]

Return Value: None

Sets the viewport to contain the given bounds.
Note: When the map is set to display: none, the fitBounds function reads the map's size as 0x0, and therefore does not do anything. To change the viewport while the map is hidden, set the map to visibility: hidden, thereby ensuring the map div has an actual size.

Set Google Maps Container DIV width and height 100%

Very few people realize the power of css positioning. To set the map to occupy 100% height of it's parent container do following:

#map_canvas_container {position: relative;}

#map_canvas {position: absolute; top: 0; right: 0; bottom: 0; left: 0;}

If you have any non absolutely positioned elements inside #map_canvas_container they will set the height of it and the map will take the exact available space.

Using Address Instead Of Longitude And Latitude With Google Maps API

var geocoder;
var map;
function initialize() {
geocoder = new google.maps.Geocoder();
var latlng = new google.maps.LatLng(-34.397, 150.644);
var mapOptions = {
  zoom: 8,
  center: latlng
map = new google.maps.Map(document.getElementById('map'), mapOptions);

function codeAddress() {
var address = document.getElementById('address').value;
geocoder.geocode( { 'address': address}, function(results, status) {
  if (status == 'OK') {
    var marker = new google.maps.Marker({
        map: map,
        position: results[0].geometry.location
  } else {
    alert('Geocode was not successful for the following reason: ' + status);

<body onload="initialize()">
 <div id="map" style="width: 320px; height: 480px;"></div>
   <input id="address" type="textbox" value="Sydney, NSW">
   <input type="button" value="Encode" onclick="codeAddress()">

Or refer to the documentation

SQL - How to find the highest number in a column?

You can also use relational algebra. A bit lengthy procedure, but here it is just to understand how MAX() works:

E := pID (Table_Name)
E1 := pID (sID >= ID' ((?ID' E) ? E)) – pID (sID < ID’ ((?ID' E) ? E))

Your answer: Table_Name ? E1

Basically what you do is subtract set of ordered relation(a,b) in which a<b from A where a, b ? A.

For relation algebra symbols see: Relational algebra From Wikipedia

Detect Android phone via Javascript / jQuery

How about this one-liner?

var isAndroid = /(android)/i.test(navigator.userAgent);

The i modifier is used to perform case-insensitive matching.

Technique taken from Cordova AdMob test project:

How to generate a random number in C++?

The most fundamental problem of your test application is that you call srand once and then call rand one time and exit.

The whole point of srand function is to initialize the sequence of pseudo-random numbers with a random seed.

It means that if you pass the same value to srand in two different applications (with the same srand/rand implementation) then you will get exactly the same sequence of rand() values read after that in both applications.

However in your example application pseudo-random sequence consists only of one element - the first element of a pseudo-random sequence generated from seed equal to current time of 1 sec precision. What do you expect to see on output then?

Obviously when you happen to run application on the same second - you use the same seed value - thus your result is the same of course (as Martin York already mentioned in a comment to the question).

Actually you should call srand(seed) one time and then call rand() many times and analyze that sequence - it should look random.


Oh I get it. Apparently verbal description is not enough (maybe language barrier or something... :) ).

OK. Old-fashioned C code example based on the same srand()/rand()/time() functions that was used in the question:

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

int main(void)
    unsigned long j;
    srand( (unsigned)time(NULL) );

    for( j = 0; j < 100500; ++j )
        int n;

        /* skip rand() readings that would make n%6 non-uniformly distributed
          (assuming rand() itself is uniformly distributed from 0 to RAND_MAX) */
        while( ( n = rand() ) > RAND_MAX - (RAND_MAX-5)%6 )
        { /* bad value retrieved so get next one */ }

        printf( "%d,\t%d\n", n, n % 6 + 1 );

    return 0;

^^^ THAT sequence from a single run of the program is supposed to look random.

Please NOTE that I don't recommend to use rand/srand functions in production for the reasons explained below and I absolutely don't recommend to use function time as a random seed for the reasons that IMO already should be quite obvious. Those are fine for educational purposes and to illustrate the point sometimes but for any serious use they are mostly useless.


When using C or C++ standard library it is important to understand that as of now there is not a single standard function or class producing actually random data definitively (guaranteed by the standard). The only standard tool that approaches this problem is std::random_device that unfortunately still does not provide guarantees of actual randomness.

Depending on the nature of application you should first decide if you really need truly random (unpredictable) data. Notable case when you do most certainly need true randomness is information security - e.g. generating symmetric keys, asymmetric private keys, salt values, security tokens, etc.

However security-grade random numbers is a separate industry worth a separate article.

In most cases Pseudo-Random Number Generator is sufficient - e.g. for scientific simulations or games. In some cases consistently defined pseudo-random sequence is even required - e.g. in games you may choose to generate exactly same maps in runtime to avoid storing lots of data.

The original question and reoccurring multitude of identical/similar questions (and even many misguided "answers" to them) indicate that first and foremost it is important to distinguish random numbers from pseudo-random numbers AND to understand what is pseudo-random number sequence in the first place AND to realize that pseudo-random number generators are NOT used the same way you could use true random number generators.

Intuitively when you request random number - the result returned shouldn't depend on previously returned values and shouldn't depend if anyone requested anything before and shouldn't depend in what moment and by what process and on what computer and from what generator and in what galaxy it was requested. That is what word "random" means after all - being unpredictable and independent of anything - otherwise it is not random anymore, right? With this intuition it is only natural to search the web for some magic spells to cast to get such random number in any possible context.

^^^ THAT kind of intuitive expectations IS VERY WRONG and harmful in all cases involving Pseudo-Random Number Generators - despite being reasonable for true random numbers.

While the meaningful notion of "random number" exists (kind of) - there is no such thing as "pseudo-random number". A Pseudo-Random Number Generator actually produces pseudo-random number sequence.

Pseudo-random sequence is in fact always deterministic (predetermined by its algorithm and initial parameters) i.e. there is actually nothing random about it.

When experts talk about quality of PRNG they actually talk about statistical properties of the generated sequence (and its notable sub-sequences). For example if you combine two high quality PRNGs by using them both in turns - you may produce bad resulting sequence - despite them generating good sequences each separately (those two good sequences may simply correlate to each other and thus combine badly).

Specifically rand()/srand(s) pair of functions provide a singular per-process non-thread-safe(!) pseudo-random number sequence generated with implementation-defined algorithm. Function rand() produces values in range [0, RAND_MAX].

Quote from C11 standard (ISO/IEC 9899:2011):

The srand function uses the argument as a seed for a new sequence of pseudo-random numbers to be returned by subsequent calls to rand. If srand is then called with the same seed value, the sequence of pseudo-random numbers shall be repeated. If rand is called before any calls to srand have been made, the same sequence shall be generated as when srand is first called with a seed value of 1.

Many people reasonably expect that rand() would produce a sequence of semi-independent uniformly distributed numbers in range 0 to RAND_MAX. Well it most certainly should (otherwise it's useless) but unfortunately not only standard doesn't require that - there is even explicit disclaimer that states "there is no guarantees as to the quality of the random sequence produced". In some historical cases rand/srand implementation was of very bad quality indeed. Even though in modern implementations it is most likely good enough - but the trust is broken and not easy to recover. Besides its non-thread-safe nature makes its safe usage in multi-threaded applications tricky and limited (still possible - you may just use them from one dedicated thread).

New class template std::mersenne_twister_engine<> (and its convenience typedefs - std::mt19937/std::mt19937_64 with good template parameters combination) provides per-object pseudo-random number generator defined in C++11 standard. With the same template parameters and the same initialization parameters different objects will generate exactly the same per-object output sequence on any computer in any application built with C++11 compliant standard library. The advantage of this class is its predictably high quality output sequence and full consistency across implementations.

Also there are more PRNG engines defined in C++11 standard - std::linear_congruential_engine<> (historically used as fair quality srand/rand algorithm in some C standard library implementations) and std::subtract_with_carry_engine<>. They also generate fully defined parameter-dependent per-object output sequences.

Modern day C++11 example replacement for the obsolete C code above:

#include <iostream>
#include <chrono>
#include <random>

int main()
    std::random_device rd;
    // seed value is designed specifically to make initialization
    // parameters of std::mt19937 (instance of std::mersenne_twister_engine<>)
    // different across executions of application
    std::mt19937::result_type seed = rd() ^ (
                ).count() +
                ).count() );

    std::mt19937 gen(seed);

    for( unsigned long j = 0; j < 100500; ++j )
    /* ^^^Yes. Generating single pseudo-random number makes no sense
       even if you use std::mersenne_twister_engine instead of rand()
       and even when your seed quality is much better than time(NULL) */    
        std::mt19937::result_type n;
        // reject readings that would make n%6 non-uniformly distributed
        while( ( n = gen() ) > std::mt19937::max() -
                                    ( std::mt19937::max() - 5 )%6 )
        { /* bad value retrieved so get next one */ }

        std::cout << n << '\t' << n % 6 + 1 << '\n';

    return 0;

The version of previous code that uses std::uniform_int_distribution<>

#include <iostream>
#include <chrono>
#include <random>

int main()
    std::random_device rd;
    std::mt19937::result_type seed = rd() ^ (
                ).count() +
                ).count() );

    std::mt19937 gen(seed);
    std::uniform_int_distribution<unsigned> distrib(1, 6);

    for( unsigned long j = 0; j < 100500; ++j )
        std::cout << distrib(gen) << ' ';

    std::cout << '\n';
    return 0;

How do I run msbuild from the command line using Windows SDK 7.1?

From Visual Studio 2013 onwards, MSbuild comes as a part of Visual Studio. Earlier, MSBuild was installed as a part of. NET Framework.

MSBuild is installed directly under %ProgramFiles%. So, the path for MSBuild might be different depending on the version of Visual Studio.

For Visual Studio 2015, Path of MSBuild is "%ProgramFiles(x86)%\MSBuild\14.0\Bin\MSBuild.exe"

For Visual Studio 15 Preview, Path of MSBuild is "%ProgramFiles(x86)%\MSBuild\15.0\Bin\MSBuild.exe"

Also, Some new MSBuild properties has been added and some have been modified. For more information look here

Update 1: VS 2017

The location for the MSBuild has changed again with the release of Visual Studio 2017. Now the installation directory is under the %ProgramFiles(x86)%\Microsoft Visual Studio\2017\[VS Edition]\MSBuild\15.0\Bin\. Since, i have an Enterprise edition, the MSBuild location for my machine is "%ProgramFiles(x86)%\Microsoft Visual Studio\2017\Enterprise\MSBuild\15.0\Bin\MSbuild.exe"

"git rebase origin" vs."git rebase origin/master"

Here's a better option:

git remote set-head -a origin

From the documentation:

With -a, the remote is queried to determine its HEAD, then $GIT_DIR/remotes//HEAD is set to the same branch. e.g., if the remote HEAD is pointed at next, "git remote set-head origin -a" will set $GIT_DIR/refs/remotes/origin/HEAD to refs/remotes/origin/next. This will only work if refs/remotes/origin/next already exists; if not it must be fetched first.

This has actually been around quite a while (since v1.6.3); not sure how I missed it!

How do I auto size a UIScrollView to fit its content

Here's a Swift 3 adaptation of @leviatan's answer :


import UIKit

extension UIScrollView {

    func resizeScrollViewContentSize() {

        var contentRect =

        for view in self.subviews {

            contentRect = contentRect.union(view.frame)


        self.contentSize = contentRect.size





Very easy to use !

Validate SSL certificates with Python

PycURL does this beautifully.

Below is a short example. It will throw a pycurl.error if something is fishy, where you get a tuple with error code and a human readable message.

import pycurl

curl = pycurl.Curl()
curl.setopt(pycurl.CAINFO, "myFineCA.crt")
curl.setopt(pycurl.SSL_VERIFYPEER, 1)
curl.setopt(pycurl.SSL_VERIFYHOST, 2)
curl.setopt(pycurl.URL, "https://internal.stuff/")


You will probably want to configure more options, like where to store the results, etc. But no need to clutter the example with non-essentials.

Example of what exceptions might be raised:

(60, 'Peer certificate cannot be authenticated with known CA certificates')
(51, "common name 'CN=something.else.stuff,O=Example Corp,C=SE' does not match 'internal.stuff'")

Some links that I found useful are the libcurl-docs for setopt and getinfo.

Why is there still a row limit in Microsoft Excel?

In a word - speed. An index for up to a million rows fits in a 32-bit word, so it can be used efficiently on 32-bit processors. Function arguments that fit in a CPU register are extremely efficient, while ones that are larger require accessing memory on each function call, a far slower operation. Updating a spreadsheet can be an intensive operation involving many cell references, so speed is important. Besides, the Excel team expects that anyone dealing with more than a million rows will be using a database rather than a spreadsheet.

How to perform OR condition in django queryset?

Both options are already mentioned in the existing answers:

from django.db.models import Q
q1 = User.objects.filter(Q(income__gte=5000) | Q(income__isnull=True))


q2 = User.objects.filter(income__gte=5000) | User.objects.filter(income__isnull=True)

However, there seems to be some confusion regarding which one is to prefer.

The point is that they are identical on the SQL level, so feel free to pick whichever you like!

The Django ORM Cookbook talks in some detail about this, here is the relevant part:

queryset = User.objects.filter(
    ) | User.objects.filter(

leads to

In [5]: str(queryset.query)
Out[5]: 'SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login",
"auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name",
"auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff",
"auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user"
WHERE ("auth_user"."first_name"::text LIKE R% OR "auth_user"."last_name"::text LIKE D%)'


qs = User.objects.filter(Q(first_name__startswith='R') | Q(last_name__startswith='D'))

leads to

In [9]: str(qs.query)
Out[9]: 'SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login",
 "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name",
  "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff",
  "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user"
  WHERE ("auth_user"."first_name"::text LIKE R% OR "auth_user"."last_name"::text LIKE D%)'

source: django-orm-cookbook

How to cin Space in c++?

It skips all whitespace (spaces, tabs, new lines, etc.) by default. You can either change its behavior, or use a slightly different mechanism. To change its behavior, use the manipulator noskipws, as follows:

 cin >> noskipws >> a[i];

But, since you seem like you want to look at the individual characters, I'd suggest using get, like this prior to your loop

 cin.get( a, n );

Note: get will stop retrieving chars from the stream if it either finds a newline char (\n) or after n-1 chars. It stops early so that it can append the null character (\0) to the array. You can read more about the istream interface here.

how to deal with google map inside of a hidden div (Updated picture)

I had the same issue, the google.maps.event.trigger(map, 'resize') wasn't working for me.

What I did was to put a timer to update the map after putting visible the div...


var refreshIntervalId;

function showMap() {
    document.getElementById('divMap').style.display = '';
    refreshIntervalId = setInterval(function () { updateMapTimer() }, 300);

function updateMapTimer() {
    var map = new google.maps.Map(....

I don't know if it's the more convenient way to do it but it works!

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

Use FromResult Method

public async Task<string> GetString()
   return await Task.FromResult("Hello");

Bootstrap 4, how to make a col have a height of 100%?

Use the Bootstrap 4 h-100 class for height:100%;

<div class="container-fluid h-100">
  <div class="row justify-content-center h-100">
    <div class="col-4 hidden-md-down" id="yellow">
    <div class="col-10 col-sm-10 col-md-10 col-lg-8 col-xl-8">
      Form Goes Here

You'll also need ensure any parent(s) are also 100% height (or have a defined height)...

html,body {
  height: 100%;

Note: 100% height is not the same as "remaining" height.

Related: Bootstrap 4: How to make the row stretch remaining height?

Append an object to a list in R in amortized constant time, O(1)?

in fact there is a subtelty with the c() function. If you do:

x <- list()
x <- c(x,2)
x = c(x,"foo")

you will obtain as expected:


[1] "foo"

but if you add a matrix with x <- c(x, matrix(5,2,2), your list will have another 4 elements of value 5 ! You would better do:

x <- c(x, list(matrix(5,2,2))

It works for any other object and you will obtain as expected:


[1] "foo"

     [,1] [,2]
[1,]    5    5
[2,]    5    5

Finally, your function becomes:

push <- function(l, ...) c(l, list(...))

and it works for any type of object. You can be smarter and do:

push_back <- function(l, ...) c(l, list(...))
push_front <- function(l, ...) c(list(...), l)

Predicate in Java

You can view the java doc examples or the example of usage of Predicate here

Basically it is used to filter rows in the resultset based on any specific criteria that you may have and return true for those rows that are meeting your criteria:

 // the age column to be between 7 and 10
    AgeFilter filter = new AgeFilter(7, 10, 3);

    // set the filter.

Cancel a UIView animation?

[UIView setAnimationsEnabled:NO];
// your code here
[UIView setAnimationsEnabled:YES];

PHP: How do you determine every Nth iteration of a loop?

How about: if(($counter % $display) == 0)

How to tell if a <script> tag failed to load

The script from Erwinus works great, but isn't very clearly coded. I took the liberty to clean it up and decipher what it was doing. I've made these changes:

  • Meaningful variable names
  • Use of prototype.
  • require() uses an argument variable
  • No alert() messages are returned by default
  • Fixed some syntax errors and scope issues I was getting

Thanks again to Erwinus, the functionality itself is spot on.

function ScriptLoader() {

ScriptLoader.prototype = {

    timer: function (times, // number of times to try
                     delay, // delay per try
                     delayMore, // extra delay per try (additional to delay)
                     test, // called each try, timer stops if this returns true
                     failure, // called on failure
                     result // used internally, shouldn't be passed
            ) {
        var me = this;
        if (times == -1 || times > 0) {
            setTimeout(function () {
                result = (test()) ? 1 : 0;
                me.timer((result) ? 0 : (times > 0) ? --times : times, delay + ((delayMore) ? delayMore : 0), delayMore, test, failure, result);
            }, (result || delay < 0) ? 0.1 : delay);
        } else if (typeof failure == 'function') {
            setTimeout(failure, 1);

    addEvent: function (el, eventName, eventFunc) {
        if (typeof el != 'object') {
            return false;

        if (el.addEventListener) {
            el.addEventListener(eventName, eventFunc, false);
            return true;

        if (el.attachEvent) {
            el.attachEvent("on" + eventName, eventFunc);
            return true;

        return false;

    // add script to dom
    require: function (url, args) {
        var me = this;
        args = args || {};

        var scriptTag = document.createElement('script');
        var headTag = document.getElementsByTagName('head')[0];
        if (!headTag) {
            return false;

        setTimeout(function () {
            var f = (typeof args.success == 'function') ? args.success : function () {
            args.failure = (typeof args.failure == 'function') ? args.failure : function () {
            var fail = function () {
                if (!scriptTag.__es) {
                    scriptTag.__es = true;
           = 'failed';
            scriptTag.onload = function () {
       = 'loaded';
            scriptTag.type = 'text/javascript';
            scriptTag.async = (typeof args.async == 'boolean') ? args.async : false;
            scriptTag.charset = 'utf-8';
            me.__es = false;
            me.addEvent(scriptTag, 'error', fail); // when supported
            // when error event is not supported fall back to timer
            me.timer(15, 1000, 0, function () {
                return ( == 'loaded');
            }, function () {
                if ( != 'loaded') {
            scriptTag.src = url;
            setTimeout(function () {
                try {
                } catch (e) {
            }, 1);
        }, (typeof args.delay == 'number') ? args.delay : 1);
        return true;

$(document).ready(function () {
    var loader = new ScriptLoader();
    loader.require('resources/templates.js', {
        async: true, success: function () {
        }, failure: function () {
            alert('NOT loaded');

angularjs directive call function specified in attribute and pass an argument to it

Just to add some info to the other answers - using & is a good way if you need an isolated scope.

The main downside of marko's solution is that it forces you to create an isolated scope on an element, but you can only have one of those on an element (otherwise you'll run into an angular error: Multiple directives [directive1, directive2] asking for isolated scope)

This means you :

  • can't use it on an element hat has an isolated scope itself
  • can't use two directives with this solution on the same element

Since the original question uses a directive with restrict:'A' both situations might arise quite often in bigger applications, and using an isolated scope here is not a good practice and also unnecessary. In fact rekna had a good intuition in this case, and almost had it working, the only thing he was doing wrong was calling the $parsed function wrong (see what it returns here:$parse ).

TL;DR; Fixed question code

<div my-method='theMethodToBeCalled(id)'></div>

and the code

app.directive("myMethod",function($parse) {
  link:function(scope,element,attrs) {
     // here you can parse any attribute (so this could as well be,
     // myDirectiveCallback or multiple ones if you need them )
     var expressionHandler = $parse(attrs.myMethod);
     $(element).on('theEvent',function( e, rowid ) {
        calculatedId = // some function called to determine id based on rowid

        // HERE: call the parsed function correctly (with scope AND params object)
        expressionHandler(scope, {id:calculatedId});

app.controller("myController",function($scope) {
   $scope.theMethodToBeCalled = function(id) { alert(id); };

Method with a bool return

Long version:

private bool booleanMethod () {
    if (your_condition) {
        return true;
    } else {
        return false;

But since you are using the outcome of your condition as the result of the method you can shorten it to

private bool booleanMethod () {
    return your_condition;

How to run stored procedures in Entity Framework Core?

Stored procedure support is not yet (as of 7.0.0-beta3) implemented in EF7. You can track the progress of this feature using issue #245.

For now, you can do it the old fashioned way using ADO.NET.

var connection = (SqlConnection)context.Database.AsSqlServer().Connection.DbConnection;

var command = connection.CreateCommand();
command.CommandType = CommandType.StoredProcedure;
command.CommandText = "MySproc";
command.Parameters.AddWithValue("@MyParameter", 42);


Eclipse "Invalid Project Description" when creating new project from existing source

Copy the project into your workspace, create new Android Application Project with the same name from eclipse file->new->project and voila.

How to set headers in http get request?

The Header field of the Request is public. You may do this :

req.Header.Set("name", "value")

HTML Button : Navigate to Other Page - Different Approaches

I use method 3 because it's the most understandable for others (whenever you see an <a> tag, you know it's a link) and when you are part of a team, you have to make simple things ;).

And finally I don't think it's useful and efficient to use JS simply to navigate to an other page.

Changing Underline color

Best way I came across doing is like this:


<p>Initial Colors <a id="new-color">Different Colors</a></p>


p {
    color: #000000;
    text-decoration-line: underline;
    text-decoration-color: #a11015;

p #new-color{
    color: #a11015;
    text-decoration-line: underline;
    text-decoration-color: #000000;

Cannot attach the file *.mdf as database

Take a look at this: Entity Framework don't create database

I would try giving the database a different name. Sometimes you can run into problems with SQL Express when trying to create a database with the same name a second time. There is a way to fix this using SQL Server Management Studio but it's generally easier to just use a different database name.

Edit This answer was accepted because it confirms the bug and the workaround used by OP (renaming database could help). I totally agree that renaming the database is not really an acceptable way, and does not totally solve the issue. Unfortunatly I didn't check the other ways to really solve it in SSMS.

Open files in 'rt' and 'wt' modes

t refers to the text mode. There is no difference between r and rt or w and wt since text mode is the default.

Documented here:

Character   Meaning
'r'     open for reading (default)
'w'     open for writing, truncating the file first
'x'     open for exclusive creation, failing if the file already exists
'a'     open for writing, appending to the end of the file if it exists
'b'     binary mode
't'     text mode (default)
'+'     open a disk file for updating (reading and writing)
'U'     universal newlines mode (deprecated)

The default mode is 'r' (open for reading text, synonym of 'rt').

MySQL - Meaning of "PRIMARY KEY", "UNIQUE KEY" and "KEY" when used together while creating a table

MySQL unique and primary keys serve to identify rows. There can be only one Primary key in a table but one or more unique keys. Key is just index.

for more details you can check

to convert mysql to mssql try this and see

How can I find out the current route in Rails?

I find that the the approved answer, request.env['PATH_INFO'], works for getting the base URL, but this does not always contain the full path if you have nested routes. You can use request.env['HTTP_REFERER'] to get the full path and then see if it matches a given route:


Recommended way to get hostname in Java

InetAddress.getLocalHost().getHostName() is the more portable way.

exec("hostname") actually calls out to the operating system to execute the hostname command.

Here are a couple other related answers on SO:

EDIT: You should take a look at A.H.'s answer or Arnout Engelen's answer for details on why this might not work as expected, depending on your situation. As an answer for this person who specifically requested portable, I still think getHostName() is fine, but they bring up some good points that should be considered.

std::vector versus std::array in C++

A vector is a container class while an array is an allocated memory.

Unable to connect with remote debugger

Inculding all impressive answers the expert developers specially Ribamar Santos provided, if you didn't get it working, you must check something more tricky!

Something like Airplane mode of your (emulated) phone! Or your network status of Emulator (Data status and Voice status on Cellular tab of Emulator configuration) that might be manipulated to don't express network! for some emulation needs!

I've overcome to this problem by this trick! It was a bit breathtaking debug to find this hole!

Play/pause HTML 5 video using JQuery

I use FancyBox and jQuery to embedd a video. Give it an ID.

Perhaps not the BEST solution could toggle play/pause differently - but easy for me and IT WORKS! :)

In the


<input type="hidden" id="current_video_playing">

<input type="hidden" id="current_video_status" value="playing">

<video id="video-1523" autobuffer="false" src="movie.mp4"></video>


// Play Pause with spacebar

$(document).keypress(function(e) { 

    theVideo = document.getElementById('current_video_playing').value

    if (e.which == 32) {

        if (document.getElementById('current_video_status').value == 'playing') {


            document.getElementById('current_video_status').value = 'paused'

        } else {

            document.getElementById('current_video_status').value = 'playing'






"ImportError: no module named 'requests'" after installing with pip

In Windows it worked for me only after trying the following: 1. Open cmd inside the folder where "requests" is unpacked. (CTRL+SHIFT+right mouse click, choose the appropriate popup menu item) 2. (Here is the path to your pip3.exe)\pip3.exe install requests Done

Request UAC elevation from within a Python script?

You can make a shortcut somewhere and as the target use: python then under properties and advanced select run as administrator.

When the user executes the shortcut it will ask them to elevate the application.

How can I make a clickable link in an NSAttributedString?

Use UITextView it supports clickable Links. Create attributed string using the following code

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:strSomeTextWithLinks];

Then set UITextView text as follows

NSDictionary *linkAttributes = @{NSForegroundColorAttributeName: [UIColor redColor],

                                 NSUnderlineColorAttributeName: [UIColor blueColor],

                                 NSUnderlineStyleAttributeName: @(NSUnderlinePatternSolid)};

customTextView.linkTextAttributes = linkAttributes; // customizes the appearance of links
textView.attributedText = attributedString;

Make sure that you enable "Selectable" behavior of the UITextView in XIB.

how to remove new lines and returns from php string?

you can pass an array of strings to str_replace, so you can do all in a single statement:

$content = str_replace(["\r\n", "\n", "\r"], "", $content);

Style input type file?

After looking around on Google for a long time, trying out several solutions, both CSS, JavaScript and JQuery, i found that most of them were using an Image as the button. Some of them were hard to use, but i did manage to piece together something that ended out working out for me.

The important parts for me was:

  • The Browse button had to be a Button (not an image).
  • The button had to have a hover effect (to make it look nice).
  • The Width of both the Text and the button had to be easy to adjust.
  • The solution had to work in IE8, FF, Chrome and Safari.

This is the solution i came up with. And hope it can be of use to others as well.

Change the width of .file_input_textbox to change the width of the textbox.

Change the width of both .file_input_div, .file_input_button and .file_input_button_hover to change the width of the button. You might need to tweak a bit on the positions also. I never figured out why...

To test this solution, make a new html file and paste the content into it.


<style type="text/css">

.file_input_textbox {height:25px;width:200px;float:left; }
.file_input_div     {position: relative;width:80px;height:26px;overflow: hidden; }
.file_input_button  {width: 80px;position:absolute;top:0px;
                     border:1px solid #F0F0EE;padding:2px 8px 2px 8px; font-weight:bold; height:25px; margin:0px; margin-right:5px; }
                     border:1px solid #0A246A; background-color:#B2BBD0;padding:2px 8px 2px 8px; height:25px; margin:0px; font-weight:bold; margin-right:5px; }
.file_input_hidden  {font-size:45px;position:absolute;right:0px;top:0px;cursor:pointer;
                     opacity:0;filter:alpha(opacity=0);-ms-filter:"alpha(opacity=0)";-khtml-opacity:0;-moz-opacity:0; }
    <input type="text" id="fileName" class="file_input_textbox" readonly="readonly">
 <div class="file_input_div">
  <input id="fileInputButton" type="button" value="Browse" class="file_input_button" />
  <input type="file" class="file_input_hidden" 
      onchange="javascript: document.getElementById('fileName').value = this.value" 
      onmouseout="document.getElementById('fileInputButton').className='file_input_button';" />

Getting error "The package appears to be corrupt" while installing apk file

In my case by making build, from Build> Build apks, it worked.

Correlation heatmap

If your data is in a Pandas DataFrame, you can use Seaborn's heatmap function to create your desired plot.

import seaborn as sns

Var_Corr = df.corr()
# plot the heatmap and annotation on it
sns.heatmap(Var_Corr, xticklabels=Var_Corr.columns, yticklabels=Var_Corr.columns, annot=True)

Correlation plot

From the question, it looks like the data is in a NumPy array. If that array has the name numpy_data, before you can use the step above, you would want to put it into a Pandas DataFrame using the following:

import pandas as pd
df = pd.DataFrame(numpy_data)

How do I use checkboxes in an IF-THEN statement in Excel VBA 2010?

You can try something like this....

Dim cbTime

Set cbTime = ActiveSheet.CheckBoxes.Add(100, 100, 50, 15)
With cbTime
    .Name = "cbTime"
    .Characters.Text = "Time"
End With

If ActiveSheet.CheckBoxes("cbTime").Value = 1 Then 'or just cbTime.Value
End If

What is the difference between Dim, Global, Public, and Private as Modular Field Access Modifiers?

Dim and Private work the same, though the common convention is to use Private at the module level, and Dim at the Sub/Function level. Public and Global are nearly identical in their function, however Global can only be used in standard modules, whereas Public can be used in all contexts (modules, classes, controls, forms etc.) Global comes from older versions of VB and was likely kept for backwards compatibility, but has been wholly superseded by Public.

How can I format a decimal to always show 2 decimal places?

The String Formatting Operations section of the Python documentation contains the answer you're looking for. In short:

"%0.2f" % (num,)

Some examples:

>>> "%0.2f" % 10
>>> "%0.2f" % 1000
>>> "%0.2f" % 10.1
>>> "%0.2f" % 10.120
>>> "%0.2f" % 10.126

Finding height in Binary Search Tree

//function to find height of BST

int height(Node* root) {
    if(root == NULL){
        return -1;

    int sum=0;
    int rheight = height(root->right);
    int lheight = height(root->left);

        sum = lheight +1;
    if(rheight > lheight){
        sum = rheight + 1;

    return sum;

Error in MySQL when setting default value for DATE or DATETIME

In diretory xamp/mysql/bin Open "my.ini" and change line: Sql_node for ->



How to add custom validation to an AngularJS form?

@synergetic I think @blesh suppose to put function validate as below

function validate(value) {
    var valid = blacklist.indexOf(value) === -1;
    ngModel.$setValidity('blacklist', valid);
    return valid ? value : undefined;


Is it better in C++ to pass by value or pass by constant reference?

It used to be generally recommended best practice1 to use pass by const ref for all types, except for builtin types (char, int, double, etc.), for iterators and for function objects (lambdas, classes deriving from std::*_function).

This was especially true before the existence of move semantics. The reason is simple: if you passed by value, a copy of the object had to be made and, except for very small objects, this is always more expensive than passing a reference.

With C++11, we have gained move semantics. In a nutshell, move semantics permit that, in some cases, an object can be passed “by value” without copying it. In particular, this is the case when the object that you are passing is an rvalue.

In itself, moving an object is still at least as expensive as passing by reference. However, in many cases a function will internally copy an object anyway — i.e. it will take ownership of the argument.2

In these situations we have the following (simplified) trade-off:

  1. We can pass the object by reference, then copy internally.
  2. We can pass the object by value.

“Pass by value” still causes the object to be copied, unless the object is an rvalue. In the case of an rvalue, the object can be moved instead, so that the second case is suddenly no longer “copy, then move” but “move, then (potentially) move again”.

For large objects that implement proper move constructors (such as vectors, strings …), the second case is then vastly more efficient than the first. Therefore, it is recommended to use pass by value if the function takes ownership of the argument, and if the object type supports efficient moving.

A historical note:

In fact, any modern compiler should be able to figure out when passing by value is expensive, and implicitly convert the call to use a const ref if possible.

In theory. In practice, compilers can’t always change this without breaking the function’s binary interface. In some special cases (when the function is inlined) the copy will actually be elided if the compiler can figure out that the original object won’t be changed through the actions in the function.

But in general the compiler can’t determine this, and the advent of move semantics in C++ has made this optimisation much less relevant.

1 E.g. in Scott Meyers, Effective C++.

2 This is especially often true for object constructors, which may take arguments and store them internally to be part of the constructed object’s state.

In Perl, how do I create a hash whose keys come from a given array?

If you do a lot of set theoretic operations - you can also use Set::Scalar or similar module. Then $s = Set::Scalar->new( @array ) will build the Set for you - and you can query it with: $s->contains($m).

How do I make a checkbox required on an ASP.NET form?

I typically perform the validation on the client side:

<asp:checkbox id="chkTerms" text=" I agree to the terms" ValidationGroup="vg" runat="Server"  />
<asp:CustomValidator id="vTerms"
                ErrorMessage="<br/>Terms and Conditions are required." 

<asp:Button ID="btnSubmit" OnClick="btnSubmit_Click" CausesValidation="true" Text="Submit" ValidationGroup="vg" runat="server" />

    function validateTerms(source, arguments) {
        var $c = $('#<%= chkTerms.ClientID %>');
            arguments.IsValid = true;
        } else {
            arguments.IsValid = false;

Deep cloning objects

I have created a version of the accepted answer that works with both '[Serializable]' and '[DataContract]'. It has been a while since I wrote it, but if I remember correctly [DataContract] needed a different serializer.

Requires System, System.IO, System.Runtime.Serialization, System.Runtime.Serialization.Formatters.Binary, System.Xml;

public static class ObjectCopier

    /// <summary>
    /// Perform a deep Copy of an object that is marked with '[Serializable]' or '[DataContract]'
    /// </summary>
    /// <typeparam name="T">The type of object being copied.</typeparam>
    /// <param name="source">The object instance to copy.</param>
    /// <returns>The copied object.</returns>
    public static T Clone<T>(T source)
        if (typeof(T).IsSerializable == true)
            return CloneUsingSerializable<T>(source);

        if (IsDataContract(typeof(T)) == true)
            return CloneUsingDataContracts<T>(source);

        throw new ArgumentException("The type must be Serializable or use DataContracts.", "source");

    /// <summary>
    /// Perform a deep Copy of an object that is marked with '[Serializable]'
    /// </summary>
    /// <remarks>
    /// Found on
    /// Uses code found on CodeProject, which allows free use in third party apps
    /// -
    /// </remarks>
    /// <typeparam name="T">The type of object being copied.</typeparam>
    /// <param name="source">The object instance to copy.</param>
    /// <returns>The copied object.</returns>
    public static T CloneUsingSerializable<T>(T source)
        if (!typeof(T).IsSerializable)
            throw new ArgumentException("The type must be serializable.", "source");

        // Don't serialize a null object, simply return the default for that object
        if (Object.ReferenceEquals(source, null))
            return default(T);

        IFormatter formatter = new BinaryFormatter();
        Stream stream = new MemoryStream();
        using (stream)
            formatter.Serialize(stream, source);
            stream.Seek(0, SeekOrigin.Begin);
            return (T)formatter.Deserialize(stream);

    /// <summary>
    /// Perform a deep Copy of an object that is marked with '[DataContract]'
    /// </summary>
    /// <typeparam name="T">The type of object being copied.</typeparam>
    /// <param name="source">The object instance to copy.</param>
    /// <returns>The copied object.</returns>
    public static T CloneUsingDataContracts<T>(T source)
        if (IsDataContract(typeof(T)) == false)
            throw new ArgumentException("The type must be a data contract.", "source");

        // ** Don't serialize a null object, simply return the default for that object
        if (Object.ReferenceEquals(source, null))
            return default(T);

        DataContractSerializer dcs = new DataContractSerializer(typeof(T));
        using(Stream stream = new MemoryStream())
            using (XmlDictionaryWriter writer = XmlDictionaryWriter.CreateBinaryWriter(stream))
                dcs.WriteObject(writer, source);
                stream.Seek(0, SeekOrigin.Begin);
                using (XmlDictionaryReader reader = XmlDictionaryReader.CreateBinaryReader(stream, XmlDictionaryReaderQuotas.Max))
                    return (T)dcs.ReadObject(reader);

    /// <summary>
    /// Helper function to check if a class is a [DataContract]
    /// </summary>
    /// <param name="type">The type of the object to check.</param>
    /// <returns>Boolean flag indicating if the class is a DataContract (true) or not (false) </returns>
    public static bool IsDataContract(Type type)
        object[] attributes = type.GetCustomAttributes(typeof(DataContractAttribute), false);
        return attributes.Length == 1;


In Java, how do I check if a string contains a substring (ignoring case)?

You can use the toLowerCase() method:

public boolean contains( String haystack, String needle ) {
  haystack = haystack == null ? "" : haystack;
  needle = needle == null ? "" : needle;

  // Works, but is not the best.
  //return haystack.toLowerCase().indexOf( needle.toLowerCase() ) > -1

  return haystack.toLowerCase().contains( needle.toLowerCase() )

Then call it using:

if( contains( str1, str2 ) ) {
  System.out.println( "Found " + str2 + " within " + str1 + "." );

Notice that by creating your own method, you can reuse it. Then, when someone points out that you should use contains instead of indexOf, you have only a single line of code to change.

How do I update/upsert a document in Mongoose?

//Here is my code to it... work like ninj

router.param('contractor', function(req, res, next, id) {
  var query = Contractors.findById(id);

  query.exec(function (err, contractor){
    if (err) { return next(err); }
    if (!contractor) { return next(new Error("can't find contractor")); }

    req.contractor = contractor;
    return next();

router.get('/contractors/:contractor/save', function(req, res, next) {

    contractor = req.contractor ;
    contractor.update({'_id':contractor._id},{upsert: true},function(err,contractor){
            return next(); 
    return res.json(contractor); 


How do you cache an image in Javascript

as @Pointy said you don't cache images with javascript, the browser does that. so this may be what you are asking for and may not be... but you can preload images using javascript. By putting all of the images you want to preload into an array and putting all of the images in that array into hidden img elements, you effectively preload (or cache) the images.

var images = [

$(images).each(function() {
var image = $('<img />').attr('src', this);

Http Servlet request lose params from POST body after read it once

you can use servlet filter chain, but instead use the original one, you can create your own request yourownrequests extends HttpServletRequestWrapper.

In Rails, how do you render JSON using a view?

You should be able to do something like this in your respond_to block:

respond_to do |format|
    render :partial => "users/show.json"

which will render the template in app/views/users/_show.json.erb.

Update a local branch with the changes from a tracked remote branch

You have set the upstream of that branch


git branch -f --track my_local_branch origin/my_remote_branch
# OR (if my_local_branch is currently checked out):
$ git branch --set-upstream-to my_local_branch origin/my_remote_branch

(git branch -f --track won't work if the branch is checked out: use the second command git branch --set-upstream-to instead, or you would get "fatal: Cannot force update the current branch.")

That means your branch is already configured with:

branch.my_local_branch.remote origin
branch.my_local_branch.merge my_remote_branch

Git already has all the necessary information.
In that case:

# if you weren't already on my_local_branch branch:
git checkout my_local_branch 
# then:
git pull

is enough.

If you hadn't establish that upstream branch relationship when it came to push your 'my_local_branch', then a simple git push -u origin my_local_branch:my_remote_branch would have been enough to push and set the upstream branch.
After that, for the subsequent pulls/pushes, git pull or git push would, again, have been enough.

Set NOW() as Default Value for datetime datatype?

My solution


C# equivalent of the IsNull() function in SQL Server

This is meant half as a joke, since the question is kinda silly.

public static bool IsNull (this System.Object o)
   return (o == null);

This is an extension method, however it extends System.Object, so every object you use now has an IsNull() method.

Then you can save tons of code by doing:

if (foo.IsNull())

instead of the super lame:

if (foo == null)

How to call a function in shell Scripting?




if [ "$choice" = "true" ] then

Why do we use arrays instead of other data structures?

Time to go back in time for a lesson. While we don't think about these things much in our fancy managed languages today, they are built on the same foundation, so let's look at how memory is managed in C.

Before I dive in, a quick explanation of what the term "pointer" means. A pointer is simply a variable that "points" to a location in memory. It doesn't contain the actual value at this area of memory, it contains the memory address to it. Think of a block of memory as a mailbox. The pointer would be the address to that mailbox.

In C, an array is simply a pointer with an offset, the offset specifies how far in memory to look. This provides O(1) access time.

  MyArray   [5]
     ^       ^
  Pointer  Offset

All other data structures either build upon this, or do not use adjacent memory for storage, resulting in poor random access look up time (Though there are other benefits to not using sequential memory).

For example, let's say we have an array with 6 numbers (6,4,2,3,1,5) in it, in memory it would look like this:

|  6  |  4  |  2  |  3  |  1  |  5  |

In an array, we know that each element is next to each other in memory. A C array (Called MyArray here) is simply a pointer to the first element:

|  6  |  4  |  2  |  3  |  1  |  5  |

If we wanted to look up MyArray[4], internally it would be accessed like this:

   0     1     2     3     4 
|  6  |  4  |  2  |  3  |  1  |  5  |
MyArray + 4 ---------------/
(Pointer + Offset)

Because we can directly access any element in the array by adding the offset to the pointer, we can look up any element in the same amount of time, regardless of the size of the array. This means that getting MyArray[1000] would take the same amount of time as getting MyArray[5].

An alternative data structure is a linked list. This is a linear list of pointers, each pointing to the next node

========    ========    ========    ========    ========
| Data |    | Data |    | Data |    | Data |    | Data |
|      | -> |      | -> |      | -> |      | -> |      | 
|  P1  |    |  P2  |    |  P3  |    |  P4  |    |  P5  |        
========    ========    ========    ========    ========

P(X) stands for Pointer to next node.

Note that I made each "node" into its own block. This is because they are not guaranteed to be (and most likely won't be) adjacent in memory.

If I want to access P3, I can't directly access it, because I don't know where it is in memory. All I know is where the root (P1) is, so instead I have to start at P1, and follow each pointer to the desired node.

This is a O(N) look up time (The look up cost increases as each element is added). It is much more expensive to get to P1000 compared to getting to P4.

Higher level data structures, such as hashtables, stacks and queues, all may use an array (or multiple arrays) internally, while Linked Lists and Binary Trees usually use nodes and pointers.

You might wonder why anyone would use a data structure that requires linear traversal to look up a value instead of just using an array, but they have their uses.

Take our array again. This time, I want to find the array element that holds the value '5'.

|  6  |  4  |  2  |  3  |  1  |  5  |
   ^     ^     ^     ^     ^   FOUND!

In this situation, I don't know what offset to add to the pointer to find it, so I have to start at 0, and work my way up until I find it. This means I have to perform 6 checks.

Because of this, searching for a value in an array is considered O(N). The cost of searching increases as the array gets larger.

Remember up above where I said that sometimes using a non sequential data structure can have advantages? Searching for data is one of these advantages and one of the best examples is the Binary Tree.

A Binary Tree is a data structure similar to a linked list, however instead of linking to a single node, each node can link to two children nodes.

         |  Root  |         
        /          \ 
  =========       =========
  | Child |       | Child |
  =========       =========
                  /       \
            =========    =========
            | Child |    | Child |
            =========    =========

 Assume that each connector is really a Pointer

When data is inserted into a binary tree, it uses several rules to decide where to place the new node. The basic concept is that if the new value is greater than the parents, it inserts it to the left, if it is lower, it inserts it to the right.

This means that the values in a binary tree could look like this:

         |   100  |         
        /          \ 
  =========       =========
  |  200  |       |   50  |
  =========       =========
                  /       \
            =========    =========
            |   75  |    |   25  |
            =========    =========

When searching a binary tree for the value of 75, we only need to visit 3 nodes ( O(log N) ) because of this structure:

  • Is 75 less than 100? Look at Right Node
  • Is 75 greater than 50? Look at Left Node
  • There is the 75!

Even though there are 5 nodes in our tree, we did not need to look at the remaining two, because we knew that they (and their children) could not possibly contain the value we were looking for. This gives us a search time that at worst case means we have to visit every node, but in the best case we only have to visit a small portion of the nodes.

That is where arrays get beat, they provide a linear O(N) search time, despite O(1) access time.

This is an incredibly high level overview on data structures in memory, skipping over a lot of details, but hopefully it illustrates an array's strength and weakness compared to other data structures.

Scroll RecyclerView to show selected item on top

In my case my RecyclerView have a padding top like this


Then for scroll a item to top, I need to

recyclerViewLinearLayoutManager.scrollToPositionWithOffset(position, -yourRecyclerView.getPaddingTop());

Extract public/private key from PKCS12 file for later use in SSH-PK-Authentication

Solution 1:

Extract P12 from jks

keytool -importkeystore -srckeystore MyRootCA.jks -destkeystore MyRootCA.p12 -deststoretype PKCS12

Extract PEM from P12 and Edit file and pem from crt file

openssl pkcs12 -in MyRootCA.p12 -clcerts -nokeys -out MyRootCA.crt

Extract key from jks

openssl pkcs12 -in MyRootCA.p12 -nocerts -out encryptedPrivateKey.pem
openssl rsa -in encryptedPrivateKey.pem -out decryptedPrivateKey.key

Solution 2:

Extract PEM and encryptedPrivateKey to txt file```

openssl pkcs12 -in MyRootCA.p12 -out keys_out.txt

Decrypt privateKey

openssl rsa -in encryptedPrivateKey.key [-outform PEM] -out decryptedPrivateKey.key

Add image to left of text via css

Very simple method:

.create:before {
content: url(image.png);

Works in all modern browsers and IE8+.


Don't use this on large sites though. The :before pseudo-element is horrible in terms of performance.

Prevent linebreak after </div>

A DIV is by default a BLOCK display element, meaning it sits on its own line. If you add the CSS property display:inline it will behave the way you want. But perhaps you should be considering a SPAN instead?

Facebook Open Graph not clearing cache

Yes, facebook automatically clears the cache every 24 hours: Actually facebook scrapes the pages and updates the cache every 24 hours

Registry key for global proxy settings for Internet Explorer 10 on Windows 8


HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\CurrentVersion\Internet Settings

EnableAutoProxyResultCache = dword: 0

How to calculate the bounding box for a given lat/lng location?

I adapted a PHP script I found to do just this. You can use it to find the corners of a box around a point (say, 20 km out). My specific example is for Google Maps API:

Escaping quotation marks in PHP

$text1= "From time to \"time\"";


$text1= 'From time to "time"';

Cannot connect to MySQL 4.1+ using old authentication

If you do not have Administrator access to the MySQL Server configuration (i.e. you are using a hosting service), then there are 2 options to get this to work:

1) Request that the old_passwords option be set to false on the MySQL server

2) Downgrade PHP to 5.2.2 until option 1 occurs.

From what I've been able to find, the issue seems to be with how the MySQL account passwords are stored and if the 'old_passwords' setting is set to true. This causes a compatibility issue between MySQL and newer versions of PHP (5.3+) where PHP attempts to connect using a 41-character hash but the MySQL server is still storing account passwords using a 16-character hash.

This incompatibility was brought about by the changing of the hashing method used in MySQL 4.1 which allows for both short and long hash lengths (Scenario 2 on this page from the MySQL site: and the inclusion of the MySQL Native Driver in PHP 5.3 (backwards compatibility issue documented on bullet 7 of this page from the PHP documentation:

How do I format a date in Jinja2?

Here's the filter that I ended up using for strftime in Jinja2 and Flask

def _jinja2_filter_datetime(date, fmt=None):
    date = dateutil.parser.parse(date)
    native = date.replace(tzinfo=None)
    format='%b %d, %Y'
    return native.strftime(format) 

And then you use the filter like so:


How do I delete an entity from symfony2


protected function templateRemove($id){
            $em = $this->getDoctrine()->getManager();
            $entity = $em->getRepository('XXXBundle:Templates')->findOneBy(array('id' => $id));

            if ($entity != null){

Python os.path.join() on a list

Assuming join wasn't designed that way (which it is, as ATOzTOA pointed out), and it only took two parameters, you could still use the built-in reduce:

>>> reduce(os.path.join,["c:/","home","foo","bar","some.txt"])

Same output like:

>>> os.path.join(*["c:/","home","foo","bar","some.txt"])

Just for completeness and educational reasons (and for other situations where * doesn't work).

Hint for Python 3

reduce was moved to the functools module.

How to make an embedded Youtube video automatically start playing?

Add &autoplay=1 to your syntax, like this

<iframe title="YouTube video player" width="480" height="390" src=";autoplay=1" frameborder="0" allowfullscreen></iframe>

What does href expression <a href="javascript:;"></a> do?

    1. Use that java script to Clear an HTML row Or Delete a row using the id set to a span and use JQuery to set a function to that span's click event.
    2. Dynamically set the div html to a string variable and replace {id} with a 1 or 2 etc. cell of a larger div table and rows

<div class="table-cell">
    <span id="clearRow{id}">
        <a href="javascript:" style-"color:#c32029; align:right; font-size:8pt;">Clear</a>

<div class="table-cell">
   <span id="deleteRow{id}">
       <a href="javascript:" style-"color:#c32029; align:right; font-size:8pt;">Delete</a>

//JQuery - Clear row
$("#clearRow" + idNum).click(function(){
    $("someIDOrWildcardSelector" + idNum).val("");
    $("someIDOrWildcardSelector" + idNum).val("");
    $("someIDOrWildcardSelector" + idNum).val("");

//JQuery to remove / delete an html row
$("#deleteRow" + idNum).click(function(){
    //depending upon levels of parent / child use 1 to many .parent().parent().parent()

The term 'Get-ADUser' is not recognized as the name of a cmdlet

If you don't see the Active Directory, it's because you did not install AD LS Users and Computer Feature. Go to Manage - Add Roles & Features. Within Add Roles and Features Wizard, on Features tab, select Remote Server Administration Tools, select - Role Admininistration Tools - Select AD DS and DF LDS Tools.

After that, you can see the PS Active Directory package.

How to pass multiple values to single parameter in stored procedure

I spent time finding a proper way. This may be useful for others.

Create a UDF and refer in the query -

PowerShell: Run command from script's directory

Well I was looking for solution for this for a while, without any scripts just from CLI. This is how I do it xD:

  • Navigate to folder from which you want to run script (important thing is that you have tab completions)


  • Now surround location with double quotes, and inside them add cd, so we could invoke another instance of powershell.

    "cd ..\..\dir"

  • Add another command to run script separated by ;, with is a command separator in powershell

    "cd ..\..\dir\; script.ps1"

  • Finally Run it with another instance of powershell

    start powershell "cd..\..\dir\; script.ps1"

This will open new powershell window, go to ..\..\dir, run script.ps1 and close window.

Note that ";" just separates commands, like you typed them one by one, if first fails second will run and next after, and next after... If you wanna keep new powershell window open you add -noexit in passed command . Note that I first navigate to desired folder so I could use tab completions (you couldn't in double quotes).

start powershell "-noexit cd..\..\dir\; script.ps1"

Use double quotes "" so you could pass directories with spaces in names e.g.,

start powershell "-noexit cd '..\..\my dir'; script.ps1"

Android: converting String to int

You can not convert to string if your integer value is zero or starts with zero (in which case 1st zero will be neglected). Try change.

int NUM=null;

Get table names using SELECT statement in MySQL

There is yet another simpler way to get table names

SHOW TABLES FROM <database_name>

How to retrieve inserted id after inserting row in SQLite using Python?

All credits to @Martijn Pieters in the comments:

You can use the function last_insert_rowid():

The last_insert_rowid() function returns the ROWID of the last row insert from the database connection which invoked the function. The last_insert_rowid() SQL function is a wrapper around the sqlite3_last_insert_rowid() C/C++ interface function.

How to check if a file exists from inside a batch file

C:\>help if

Performs conditional processing in batch programs.

IF [NOT] ERRORLEVEL number command

IF [NOT] string1==string2 command

IF [NOT] EXIST filename command

How do I do an initial push to a remote repository with Git?

I am aware there are existing answers which solves the problem. For those who are new to git, As of 02/11/2021, The default branch in git is "main" not "master" branch, The command will be

git push -u origin main

Where should I put the file?

You can specify config file location with VM argument -Dlog4j.configuration="file:/C:/workspace3/local/"

How can I clone an SQL Server database on the same server in SQL Server 2008 Express?

You could try to detach the database, copy the files to new names at a command prompt, then attach both DBs.


USE master;
EXEC sp_detach_db
    @dbname = N'OriginalDB';

At Command prompt (I've simplified the file paths for the sake of this example):

copy c:\OriginalDB.mdf c:\NewDB.mdf
copy c:\OriginalDB.ldf c:\NewDB.ldf

In SQL again:

USE master;
    ON (FILENAME = 'C:\OriginalDB.mdf'),
       (FILENAME = 'C:\OriginalDB.ldf')
    ON (FILENAME = 'C:\NewDB.mdf'),
       (FILENAME = 'C:\NewDB.ldf')

Make new column in Panda dataframe by adding values from other columns

You could use sum function to achieve that as @EdChum mentioned in the comment:

df['C'] =  df[['A', 'B']].sum(axis=1)

In [245]: df
   A  B   C
0  1  4   5
1  2  6   8
2  3  9  12

C# Regex for Guid

You can easily auto-generate the C# code using:

Its free.

Here is how I did it:

enter image description here

The website then auto-generates the .NET code:

string strRegex = @"\b[A-F0-9]{8}(?:-[A-F0-9]{4}){3}-[A-F0-9]{12}\b";
Regex myRegex = new Regex(strRegex, RegexOptions.None);
string strTargetString = @"     {CD73FAD2-E226-4715-B6FA-14EDF0764162}.Debug|x64.ActiveCfg =         Debug|x64";
string strReplace = @"""$0""";

return myRegex.Replace(strTargetString, strReplace);

Print values for multiple variables on the same line from within a for-loop

Try out cat and sprintf in your for loop.


cat(sprintf("\"%f\" \"%f\"\n", df$r, df$interest))

See here

What is the difference between a schema and a table and a database?

A relation schema is the logical definition of a table - it defines what the name of the table is, and what the name and type of each column is. It's like a plan or a blueprint. A database schema is the collection of relation schemas for a whole database.

A table is a structure with a bunch of rows (aka "tuples"), each of which has the attributes defined by the schema. Tables might also have indexes on them to aid in looking up values on certain columns.

A database is, formally, any collection of data. In this context, the database would be a collection of tables. A DBMS (Database Management System) is the software (like MySQL, SQL Server, Oracle, etc) that manages and runs a database.

Looping through all the properties of object php

If this is just for debugging output, you can use the following to see all the types and values as well.


If you want more control over the output you can use this:

foreach ($obj as $key => $value) {
    echo "$key => $value\n";

What is the difference between a pandas Series and a single-column DataFrame?

Series is a one-dimensional object that can hold any data type such as integers, floats and strings e.g

   import pandas as pd
   x = pd.Series([A,B,C]) 

0 A
1 B
2 C

The first column of Series is known as index i.e 0,1,2 the second column is your actual data i.e A,B,C

DataFrames is two-dimensional object that can hold series, list, dictionary


submitting a GET form with query string params and hidden params disappear

I had a very similar problem where for the form action, I had something like:

<form action="" method="GET">
   <input type="submit" value="Go away..." />&nbsp;

The button would get the user to the site, but the query info disappeared so the user landed on the home page rather than the desired content page. The solution in my case was to find out how to code the URL without the query that would get the user to the desired page. In this case my target was a Drupal site, so as it turned out /content/something also worked. I also could have used a node number (i.e. /node/123).

Javascript to export html table to Excel

For UTF 8 Conversion and Currency Symbol Export Use this:

var tableToExcel = (function() {
  var uri = 'data:application/;base64,'
    , template = '<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns=""><head><!--[if gte mso 9]><?xml version="1.0" encoding="UTF-8" standalone="yes"?><x:ExcelWorkbook><x:ExcelWorksheets><x:ExcelWorksheet><x:Name>{worksheet}</x:Name><x:WorksheetOptions><x:DisplayGridlines/></x:WorksheetOptions></x:ExcelWorksheet></x:ExcelWorksheets></x:ExcelWorkbook></xml><![endif]--></head><body><table>{table}</table></body></html>'
    , base64 = function(s) { return window.btoa(unescape(encodeURIComponent(s))) }
    , format = function(s, c) { return s.replace(/{(\w+)}/g, function(m, p) { return c[p]; }) }
  return function(table, name) {
      if (!table.nodeType) table = document.getElementById(table)
      var ctx = { worksheet: name || 'Worksheet', table: table.innerHTML }
    window.location.href = uri + base64(format(template, ctx))

Cannot make Project Lombok work on Eclipse

It was little frustrating. But finally it got resolved for me with following solution.

The issue seems to be where "-javaagent:lombok.jar" is placed in your ini file. When i installed it through lombok installation. This line got added towards last parameters after -vmargs. When i moved it up next to -vmargs. the issue got resolved.

Python Array with String Indices

Even better, try an OrderedDict (assuming you want something like a list). Closer to a list than a regular dict since the keys have an order just like list elements have an order. With a regular dict, the keys have an arbitrary order.

Note that this is available in Python 3 and 2.7. If you want to use with an earlier version of Python you can find installable modules to do that.

How can I remove or replace SVG content?

If you want to get rid of all children,


will remove all content associated with the svg.

Joining two table entities in Spring Data JPA

This has been an old question but solution is very simple to that. If you are ever unsure about how to write criterias, joins etc in hibernate then best way is using native queries. This doesn't slow the performance and very useful. Eq. below

    @Query(nativeQuery = true, value = "your sql query")
returnTypeOfMethod methodName(arg1, arg2);

Automatically pass $event with ng-click?

Add a $event to the ng-click, for example:

<button type="button" ng-click="saveOffer($event)" accesskey="S"></button>

Then the jQuery.Event was passed to the callback:

enter image description here

How to access model hasMany Relation with where condition?

I have fixed the similar issue by passing associative array as the first argument inside Builder::with method.

Imagine you want to include child relations by some dynamic parameters but don't want to filter parent results.


public function child ()
    return $this->hasMany(ChildModel::class);

Then, in other place, when your logic is placed you can do something like filtering relation by HasMany class. For example (very similar to my case):

$search = 'Some search string';
$result = Model::query()->with(
        'child' => function (HasMany $query) use ($search) {
            $query->where('name', 'like', "%{$search}%");

Then you will filter all the child results but parent models will not filter. Thank you for attention.

Default string initialization: NULL or Empty?

+1 for distinguishing between "empty" and NULL. I agree that "empty" should mean "valid, but blank" and "NULL" should mean "invalid."

So I'd answer your question like this:

empty when I want a valid default value that may or may not be changed, for example, a user's middle name.

NULL when it is an error if the ensuing code does not set the value explicitly.

Hide text within HTML?

Here are two ways you can achieve this

You can display none or have a opacity none...But if you want the opacity to be cross browser compatible you would have to add this to your css

/* IE 8 */
-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";

/* IE 5-7 */
filter: alpha(opacity=50);

/* Netscape */
-moz-opacity: 0.5;

/* Safari 1.x */
-khtml-opacity: 0.5;

/* Good browsers */
opacity: 0.5;

Center the nav in Twitter Bootstrap

Possible duplicate of Modify twitter bootstrap navbar. I guess this is what you are looking for (copied):

.navbar .nav,
.navbar .nav > li {
  *display:inline; /* ie7 fix */
  *zoom:1; /* hasLayout ie7 trigger */
  vertical-align: top;

.navbar-inner {

As stated in the linked answer, you should make a new class with these properties and add it to the nav div.

How many bits or bytes are there in a character?

It depends what is the character and what encoding it is in:

  • An ASCII character in 8-bit ASCII encoding is 8 bits (1 byte), though it can fit in 7 bits.

  • An ISO-8895-1 character in ISO-8859-1 encoding is 8 bits (1 byte).

  • A Unicode character in UTF-8 encoding is between 8 bits (1 byte) and 32 bits (4 bytes).

  • A Unicode character in UTF-16 encoding is between 16 (2 bytes) and 32 bits (4 bytes), though most of the common characters take 16 bits. This is the encoding used by Windows internally.

  • A Unicode character in UTF-32 encoding is always 32 bits (4 bytes).

  • An ASCII character in UTF-8 is 8 bits (1 byte), and in UTF-16 - 16 bits.

  • The additional (non-ASCII) characters in ISO-8895-1 (0xA0-0xFF) would take 16 bits in UTF-8 and UTF-16.

That would mean that there are between 0.03125 and 0.125 characters in a bit.

Spring default behavior for lazy-init

lazy-init is the attribute of bean. The values of lazy-init can be true and false. If lazy-init is true, then that bean will be initialized when a request is made to bean. This bean will not be initialized when the spring container is initialized and if lazy-init is false then the bean will be initialized with the spring container initialization.

how to stop a loop arduino

This isn't published on but you can in fact exit from the loop routine with a simple exit(0);

This will compile on pretty much any board you have in your board list. I'm using IDE 1.0.6. I've tested it with Uno, Mega, Micro Pro and even the Adafruit Trinket

void loop() {
// All of your code here

/* Note you should clean up any of your I/O here as on exit, 
all 'ON'outputs remain HIGH */

// Exit the loop 
exit(0);  //The 0 is required to prevent compile error.

I use this in projects where I wire in a button to the reset pin. Basically your loop runs until exit(0); and then just persists in the last state. I've made some robots for my kids, and each time the press a button (reset) the code starts from the start of the loop() function.

Download and save PDF file with Python requests module

Generally, this should work in Python3:

import urllib.request 

Remember that urllib and urllib2 don't work properly after Python2.

If in some mysterious cases requests don't work (happened with me), you can also try using


Here's a decent explanation/solution to find and download all pdf files on a webpage:

Synchronous request in Node.js

Using the request library can help minimize the cruft:

var request = require('request')

request({ uri: '' }, function(err, response, body){
    // use body
    request({ uri: '' }, function(err, response, body){
        // use body
        request({ uri: '' }, function(err, response, body){
            // use body

But for maximum awesomeness you should try some control-flow library like Step - it will also allow you to parallelize requests, assuming that it's acceptable:

var request = require('request')
var Step    = require('step')

// request returns body as 3rd argument
// we have to move it so it works with Step :(
request.getBody = function(o, cb){
    request(o, function(err, resp, body){
        cb(err, body)

    function getData(){
        request.getBody({ uri: '' }, this.parallel())
        request.getBody({ uri: '' }, this.parallel())
        request.getBody({ uri: '' }, this.parallel())
    function doStuff(err, r1, r2, r3){

What is the meaning of ImagePullBackOff status on a Kubernetes pod?

One issue that may cause an ImagePullBackOff especially if you are pulling from a private registry is if the pod is not configured with the imagePullSecret of the private registry.

An authentication error may cause an imagePullBackOff.

pandas: merge (join) two data frames on multiple columns

the problem here is that by using the apostrophes you are setting the value being passed to be a string, when in fact, as @Shijo stated from the documentation, the function is expecting a label or list, but not a string! If the list contains each of the name of the columns beings passed for both the left and right dataframe, then each column-name must individually be within apostrophes. With what has been stated, we can understand why this is inccorect:

new_df = pd.merge(A_df, B_df,  how='left', left_on='[A_c1,c2]', right_on = '[B_c1,c2]')

And this is the correct way of using the function:

new_df = pd.merge(A_df, B_df,  how='left', left_on=['A_c1','c2'], right_on = ['B_c1','c2'])

Python `if x is not None` or `if not x is None`?

Python if x is not None or if not x is None?

TLDR: The bytecode compiler parses them both to x is not None - so for readability's sake, use if x is not None.


We use Python because we value things like human readability, useability, and correctness of various paradigms of programming over performance.

Python optimizes for readability, especially in this context.

Parsing and Compiling the Bytecode

The not binds more weakly than is, so there is no logical difference here. See the documentation:

The operators is and is not test for object identity: x is y is true if and only if x and y are the same object. x is not y yields the inverse truth value.

The is not is specifically provided for in the Python grammar as a readability improvement for the language:

comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'

And so it is a unitary element of the grammar as well.

Of course, it is not parsed the same:

>>> import ast
>>> ast.dump(ast.parse('x is not None').body[0].value)
"Compare(left=Name(id='x', ctx=Load()), ops=[IsNot()], comparators=[Name(id='None', ctx=Load())])"
>>> ast.dump(ast.parse('not x is None').body[0].value)
"UnaryOp(op=Not(), operand=Compare(left=Name(id='x', ctx=Load()), ops=[Is()], comparators=[Name(id='None', ctx=Load())]))"

But then the byte compiler will actually translate the not ... is to is not:

>>> import dis
>>> dis.dis(lambda x, y: x is not y)
  1           0 LOAD_FAST                0 (x)
              3 LOAD_FAST                1 (y)
              6 COMPARE_OP               9 (is not)
              9 RETURN_VALUE
>>> dis.dis(lambda x, y: not x is y)
  1           0 LOAD_FAST                0 (x)
              3 LOAD_FAST                1 (y)
              6 COMPARE_OP               9 (is not)
              9 RETURN_VALUE

So for the sake of readability and using the language as it was intended, please use is not.

To not use it is not wise.

How do I clear a search box with an 'x' in bootstrap 3?

Thanks unwired your solution was very clean. I was using horizontal bootstrap forms and made a couple modifications to allow for a single handler and form css.

html: - UPDATED to use Bootstrap's has-feedback and form-control-feedback

 <div class="container">
  <form class="form-horizontal">
   <div class="form-group has-feedback">
    <label for="txt1" class="col-sm-2 control-label">Label 1</label>
    <div class="col-sm-10">
     <input id="txt1" type="text" class="form-control hasclear" placeholder="Textbox 1">
     <span class="clearer glyphicon glyphicon-remove-circle form-control-feedback"></span>
   <div class="form-group has-feedback">
    <label for="txt2" class="col-sm-2 control-label">Label 2</label>
    <div class="col-sm-10">
      <input id="txt2" type="text" class="form-control hasclear" placeholder="Textbox 2">
      <span class="clearer glyphicon glyphicon-remove-circle form-control-feedback"></span>
   <div class="form-group has-feedback">
    <label for="txt3" class="col-sm-2 control-label">Label 3</label>
    <div class="col-sm-10">
     <input id="txt3" type="text" class="form-control hasclear" placeholder="Textbox 3">
     <span class="clearer glyphicon glyphicon-remove-circle form-control-feedback"></span>


$(".hasclear").keyup(function () {
    var t = $(this);'span').toggle(Boolean(t.val()));
$(".clearer").click(function () {


Simplest way to read json from a URL in java

It's very easy, using jersey-client, just include this maven dependency:


Then invoke it using this example:

String json = ClientBuilder.newClient().target("").request().accept(MediaType.APPLICATION_JSON).get(String.class);

Then use Google's Gson to parse the JSON:

Gson gson = new Gson();
Type gm = new TypeToken<CoinDeskMessage>() {}.getType();
CoinDeskMessage cdm = gson.fromJson(json, gm);

Git merge without auto commit

Note the output while doing the merge - it is saying Fast Forward

In such situations, you want to do:

git merge v1.0 --no-commit --no-ff

How to provide user name and password when connecting to a network share

You should be looking at adding a like like this:

<identity impersonate="true" userName="domain\user" password="****" />

Into your web.config.

More Information.

How to validate domain credentials?

C# in .NET 3.5 using System.DirectoryServices.AccountManagement.

 bool valid = false;
 using (PrincipalContext context = new PrincipalContext(ContextType.Domain))
     valid = context.ValidateCredentials( username, password );

This will validate against the current domain. Check out the parameterized PrincipalContext constructor for other options.

How to use unicode characters in Windows command line?

My background: I use Unicode input/output in a console for years (and do it a lot daily. Moreover, I develop support tools for exactly this task). There are very few problems, as far as you understand the following facts/limitations:

  • CMD and “console” are unrelated factors. CMD.exe is a just one of programs which are ready to “work inside” a console (“console applications”).
  • AFAIK, CMD has perfect support for Unicode; you can enter/output all Unicode chars when any codepage is active.
  • Windows’ console has A LOT of support for Unicode — but it is not perfect (just “good enough”; see below).
  • chcp 65001 is very dangerous. Unless a program was specially designed to work around defects in the Windows’ API (or uses a C runtime library which has these workarounds), it would not work reliably. Win8 fixes ½ of these problems with cp65001, but the rest is still applicable to Win10.
  • I work in cp1252. As I already said: To input/output Unicode in a console, one does not need to set the codepage.

The details

  • To read/write Unicode to a console, an application (or its C runtime library) should be smart enough to use not File-I/O API, but Console-I/O API. (For an example, see how Python does it.)
  • Likewise, to read Unicode command-line arguments, an application (or its C runtime library) should be smart enough to use the corresponding API.
  • Console font rendering supports only Unicode characters in BMP (in other words: below U+10000). Only simple text rendering is supported (so European — and some East Asian — languages should work fine — as far as one uses precomposed forms). [There is a minor fine print here for East Asian and for characters U+0000, U+0001, U+30FB.]

Practical considerations

  • The defaults on Window are not very helpful. For best experience, one should tune up 3 pieces of configuration:

    • For output: a comprehensive console font. For best results, I recommend my builds. (The installation instructions are present there — and also listed in other answers on this page.)
    • For input: a capable keyboard layout. For best results, I recommend my layouts.
    • For input: allow HEX input of Unicode.
  • One more gotcha with “Pasting” into a console application (very technical):

    • HEX input delivers a character on KeyUp of Alt; all the other ways to deliver a character happen on KeyDown; so many applications are not ready to see a character on KeyUp. (Only applicable to applications using Console-I/O API.)
    • Conclusion: many application would not react on HEX input events.
    • Moreover, what happens with a “Pasted” character depends on the current keyboard layout: if the character can be typed without using prefix keys (but with arbitrary complicated combination of modifiers, as in Ctrl-Alt-AltGr-Kana-Shift-Gray*) then it is delivered on an emulated keypress. This is what any application expects — so pasting anything which contains only such characters is fine.
    • However, the “other” characters are delivered by emulating HEX input.

    Conclusion: unless your keyboard layout supports input of A LOT of characters without prefix keys, some buggy applications may skip characters when you Paste via Console’s UI: Alt-Space E P. (This is why I recommend using my keyboard layouts!)

One should also keep in mind that the “alternative, ‘more capable’ consoles” for Windows are not consoles at all. They do not support Console-I/O APIs, so the programs which rely on these APIs to work would not function. (The programs which use only “File-I/O APIs to the console filehandles” would work fine, though.)

One example of such non-console is a part of MicroSoft’s Powershell. I do not use it; to experiment, press and release WinKey, then type powershell.

(On the other hand, there are programs such as ConEmu or ANSICON which try to do more: they “attempt” to intercept Console-I/O APIs to make “true console applications” work too. This definitely works for toy example programs; in real life, this may or may not solve your particular problems. Experiment.)


  • set font, keyboard layout (and optionally, allow HEX input).

  • use only programs which go through Console-I/O APIs, and accept Unicode command-line arguments. For example, any cygwin-compiled program should be fine. As I already said, CMD is fine too.

UPD: Initially, for a bug in cp65001, I was mixing up Kernel and CRTL layers (UPD²: and Windows user-mode API!). Also: Win8 fixes one half of this bug; I clarified the section about “better console” application, and added a reference to how Python does it.

jQuery $("#radioButton").change(...) not firing during de-selection

You can bind to all of the radio buttons at once by name:


Working example here:

How to install gdb (debugger) in Mac OSX El Capitan?

Once you get the macports version of gdb installed you will need to disable SIP in order to make the proper edits to /System/Library/LaunchDaemons/ To disable SIP, you need to restart in recovery mode and execute the following command:

csrutil disable

Then restart. Then you will need to edit the bottom part of like this:


Then you will have to restart to have the changes take effect. Then you should reenable SIP. The gdb command for the macports install is actually ggdb. You will need to code sign ggdb following the instructions here:

The only way I have been able to get the code signing to work is by running ggdb with sudo. Good luck!

Add a new column to existing table in a migration

Add column to your migration file and run this command.

php artisan migrate:refresh --path=/database/migrations/your_file_name.php

Python: import module from another directory at the same level in project hierarchy

I faced the same issues. To solve this, I used export PYTHONPATH="$PWD". However, in this case, you will need to modify imports in your Scripts dir depending on the below:

Case 1: If you are in the user_management dir, your scripts should use this style from Modules import LDAPManager to import module.

Case 2: If you are out of the user_management 1 level like main, your scripts should use this style from user_management.Modules import LDAPManager to import modules.

Failed to Connect to MySQL at localhost:3306 with user root

Go to system preferences, then "MySQL"

Click on "Start MySQL Server"

Go to system preferences, then "MySQL". Click on "Start MySQL Server".

How to change spinner text size and text color?

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="" 

just use this:

ArrayAdapter<String> adapter_category = new ArrayAdapter<String>(this,
    R.layout.spinner_list_item, categories);

How can you change Network settings (IP Address, DNS, WINS, Host Name) with code in C#

The existing answers have quite broken code. The DNS method does not work at all. Here is code that I used to configure my NIC:

public static class NetworkConfigurator
    /// <summary>
    /// Set's a new IP Address and it's Submask of the local machine
    /// </summary>
    /// <param name="ipAddress">The IP Address</param>
    /// <param name="subnetMask">The Submask IP Address</param>
    /// <param name="gateway">The gateway.</param>
    /// <param name="nicDescription"></param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetIP(string nicDescription, string[] ipAddresses, string subnetMask, string gateway)
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
            using (var networkConfigs = networkConfigMng.GetInstances())
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                    using (var newIP = managementObject.GetMethodParameters("EnableStatic"))
                        // Set new IP address and subnet if needed
                        if (ipAddresses != null || !String.IsNullOrEmpty(subnetMask))
                            if (ipAddresses != null)
                                newIP["IPAddress"] = ipAddresses;

                            if (!String.IsNullOrEmpty(subnetMask))
                                newIP["SubnetMask"] = Array.ConvertAll(ipAddresses, _ => subnetMask);

                            managementObject.InvokeMethod("EnableStatic", newIP, null);

                        // Set mew gateway if needed
                        if (!String.IsNullOrEmpty(gateway))
                            using (var newGateway = managementObject.GetMethodParameters("SetGateways"))
                                newGateway["DefaultIPGateway"] = new[] { gateway };
                                newGateway["GatewayCostMetric"] = new[] { 1 };
                                managementObject.InvokeMethod("SetGateways", newGateway, null);

    /// <summary>
    /// Set's the DNS Server of the local machine
    /// </summary>
    /// <param name="nic">NIC address</param>
    /// <param name="dnsServers">Comma seperated list of DNS server addresses</param>
    /// <remarks>Requires a reference to the System.Management namespace</remarks>
    public static void SetNameservers(string nicDescription, string[] dnsServers)
        using (var networkConfigMng = new ManagementClass("Win32_NetworkAdapterConfiguration"))
            using (var networkConfigs = networkConfigMng.GetInstances())
                foreach (var managementObject in networkConfigs.Cast<ManagementObject>().Where(mo => (bool)mo["IPEnabled"] && (string)mo["Description"] == nicDescription))
                    using (var newDNS = managementObject.GetMethodParameters("SetDNSServerSearchOrder"))
                        newDNS["DNSServerSearchOrder"] = dnsServers;
                        managementObject.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);

Why does JPA have a @Transient annotation?

As others have said, @Transient is used to mark fields which shouldn't be persisted. Consider this short example:

public enum Gender { MALE, FEMALE, UNKNOWN }

public Person {
    private Gender g;
    private long id;

    public long getId() { return id; }
    public void setId(long id) { = id; }

    public Gender getGender() { return g; }    
    public void setGender(Gender g) { this.g = g; }

    public boolean isMale() {
        return Gender.MALE.equals(g);

    public boolean isFemale() {
        return Gender.FEMALE.equals(g);

When this class is fed to the JPA, it persists the gender and id but doesn't try to persist the helper boolean methods - without @Transient the underlying system would complain that the Entity class Person is missing setMale() and setFemale() methods and thus wouldn't persist Person at all.


PHP uses one of two methods to keep track of sessions. If cookies are enabled, like in your case, it uses them.

If cookies are disabled, it uses the URL. Although this can be done securely, it's harder and it often, well, isn't. See, e.g., session fixation.

Search for it, you will get lots of SEO advice. The conventional wisdom is that you should use the cookies, but php will keep track of the session either way.

Facebook Graph API : get larger pictures in one request

Hum... I think I've found a solution.

In fact, in can just request,name

According to (section "Pictures"), url of profile's photos can be built with the user id

For example, assuming user id is in $id :


But it's not the final image URL, so if someone have a better solution, i would be glad to know :)

Typescript Type 'string' is not assignable to type

I had a similar issue when passing props to a React Component.

Reason: My type inference on myArray wasn't working correctly

Special thanks to Brady from Reactiflux for helping with this issue.

Determine .NET Framework version for dll

Just simply

var tar = (TargetFrameworkAttribute)Assembly

How can I print out C++ map values?

Since C++17 you can use range-based for loops together with structured bindings for iterating over your map. This improves readability, as you reduce the amount of needed first and second members in your code:

std::map<std::string, std::pair<std::string, std::string>> myMap;
myMap["x"] = { "a", "b" };
myMap["y"] = { "c", "d" };

for (const auto &[k, v] : myMap)
    std::cout << "m[" << k << "] = (" << v.first << ", " << v.second << ") " << std::endl;


m[x] = (a, b)
m[y] = (c, d)

Code on Coliru

Adding Buttons To Google Sheets and Set value to Cells on clicking

You can insert an image that looks like a button. Then attach a script to the image.

  • INSERT menu
  • Image

Insert Image

You can insert any image. The image can be edited in the spreadsheet

Edit Image

Image of a Button

Image of Button

Assign a function name to an image:

Assign Function

Android sqlite how to check if a record exists

public static boolean CheckIsDataAlreadyInDBorNot(String TableName,
        String dbfield, String fieldValue) {
    SQLiteDatabase sqldb = EGLifeStyleApplication.sqLiteDatabase;
    String Query = "Select * from " + TableName + " where " + dbfield + " = " + fieldValue;
    Cursor cursor = sqldb.rawQuery(Query, null);
        if(cursor.getCount() <= 0){
            return false;
    return true;

I hope this is useful to you... This function returns true if record already exists in db. Otherwise returns false.

OnclientClick and OnClick is not working at the same time?

What if you don't immediately set the button to disabled, but delay that through setTimeout? Your 'disable' function would return and the submit would continue.

How to solve "Connection reset by peer: socket write error"?

I've got the same exception and in my case the problem was in a renegotiation procecess. In fact my client closed a connection when the server tried to change a cipher suite. After digging it appears that in the jdk 1.6 update 22 renegotiation process is disabled by default. If your security constraints can effort this, try to enable the unsecure renegotiation by setting the system property to true. Here is some information about the process:

Session renegotiation is a mechanism within the SSL protocol that allows the client or the server to trigger a new SSL handshake during an ongoing SSL communication. Renegotiation was initially designed as a mechanism to increase the security of an ongoing SSL channel, by triggering the renewal of the crypto keys used to secure that channel. However, this security measure isn't needed with modern cryptographic algorithms. Additionally, renegotiation can be used by a server to request a client certificate (in order to perform client authentication) when the client tries to access specific, protected resources on the server.

Additionally there is the excellent post about this issue in details and written in (IMHO) understandable language.

Examples of Algorithms which has O(1), O(n log n) and O(log n) complexities

O(1) - most cooking procedures are O(1), that is, it takes a constant amount of time even if there are more people to cook for (to a degree, because you could run out of space in your pot/pans and need to split up the cooking)

O(logn) - finding something in your telephone book. Think binary search.

O(n) - reading a book, where n is the number of pages. It is the minimum amount of time it takes to read a book.

O(nlogn) - cant immediately think of something one might do everyday that is nlogn...unless you sort cards by doing merge or quick sort!

how to install gcc on windows 7 machine?

Download mingw-get and simply issue:

mingw-get install gcc.

See the Getting Started page.

Resetting a multi-stage form with jQuery

There's a big problem with Paolo's accepted answer. Consider:

 .not(':button, :submit, :reset, :hidden')

The .val('') line will also clear any value's assigned to checkboxes and radio buttons. So if (like me) you do something like this:

<input type="checkbox" name="list[]" value="one" />
<input type="checkbox" name="list[]" value="two" checked="checked" />
<input type="checkbox" name="list[]" value="three" />

Using the accepted answer will transform your inputs into:

<input type="checkbox" name="list[]" value="" />
<input type="checkbox" name="list[]" value="" />
<input type="checkbox" name="list[]" value="" />

Oops - I was using that value!

Here's a modified version that will keep your checkbox and radio values:

// Use a whitelist of fields to minimize unintended side effects.
$('INPUT:text, INPUT:password, INPUT:file, SELECT, TEXTAREA', '#myFormId').val('');  
// De-select any checkboxes, radios and drop-down menus
$('INPUT:checkbox, INPUT:radio', '#myFormId').removeAttr('checked').removeAttr('selected');

Postman - How to see request with headers and body data with variables substituted

As of now, Postman comes with its own "Console." Click the terminal-like icon on the bottom left to open the console. Send a request, and you can inspect the request from within Postman's console.

enter image description here

How to start debug mode from command prompt for apache tomcat server?

First, Navigate to the TOMCAT-HOME/bin directory.

Then, Execute the following in the command-line:

catalina.bat jpda start

If the Tomcat server is running under Linux, just invoke the program jpda start

It's the same for Tomcat 5.5 and Tomcat 6

SQL Server Express CREATE DATABASE permission denied in database 'master'

i have same problem, and i try this:

  1. log In As Administrator on your PC
  2. log In SQL Server Management Studio as "Windows Aunthication"
  3. Click Security > Login > choose your login where you want to create DB > right click then Properties > click server roles > then checklist 'dbcreator'.
  4. Close and log in back with your login account.

This worked for me, and hope will help you.

*sorry for my bad english

How to restart Jenkins manually?

If you run FreeBSD:

/usr/local/etc/rc.d/jenkins restart

Razor View throwing "The name 'model' does not exist in the current context"

Make sure you have the following in both your site Web.config and views directory Web.config in the appSettings section

<add key="webpages:Version" value="" />

For MVC5 use:

<add key="webpages:Version" value="" />

(And it only exists in the main Web.config file.)

how to reference a YAML "setting" from elsewhere in the same YAML file?

With Yglu, you can write your example as:

  root: /path/to/root/
  patha: !? .paths.root + a
  pathb: !? .paths.root + b
  pathc: !? .paths.root + c

Disclaimer: I am the author of Yglu.

return, return None, and no return at all?

They each return the same singleton None -- There is no functional difference.

I think that it is reasonably idiomatic to leave off the return statement unless you need it to break out of the function early (in which case a bare return is more common), or return something other than None. It also makes sense and seems to be idiomatic to write return None when it is in a function that has another path that returns something other than None. Writing return None out explicitly is a visual cue to the reader that there's another branch which returns something more interesting (and that calling code will probably need to handle both types of return values).

Often in Python, functions which return None are used like void functions in C -- Their purpose is generally to operate on the input arguments in place (unless you're using global data (shudders)). Returning None usually makes it more explicit that the arguments were mutated. This makes it a little more clear why it makes sense to leave off the return statement from a "language conventions" standpoint.

That said, if you're working in a code base that already has pre-set conventions around these things, I'd definitely follow suit to help the code base stay uniform...

SQL Error: ORA-01861: literal does not match format string 01861

The format you use for the date doesn't match to Oracle's default date format.

A default installation of Oracle Database sets the DEFAULT DATE FORMAT to dd-MMM-yyyy.

Either use the function TO_DATE(dateStr, formatStr) or simply use dd-MMM-yyyy date format model.

How to find if an array contains a string

Using the code from my answer to a very similar question:

Sub DoSomething()
Dim Mainfram(4) As String
Dim cell As Excel.Range

Mainfram(0) = "apple"
Mainfram(1) = "pear"
Mainfram(2) = "orange"
Mainfram(3) = "fruit"

For Each cell In Selection
  If IsInArray(cell.Value, MainFram) Then
    Row(cell.Row).Style = "Accent1"
  End If
Next cell

End Sub

Function IsInArray(stringToBeFound As String, arr As Variant) As Boolean
  IsInArray = (UBound(Filter(arr, stringToBeFound)) > -1)
End Function

Save Javascript objects in sessionStorage

The solution is to stringify the object before calling setItem on the sessionStorage.

var user = {'name':'John'};
sessionStorage.setItem('user', JSON.stringify(user));
var obj = JSON.parse(sessionStorage.user);

Chrome says my extension's manifest file is missing or unreadable

Some permissions issue for default sample.

I wanted to see how it works, I am creating the first extension, so I downloaded a simpler one.

Downloaded 'Typed URL History' sample from

which can be found at

this worked great, hope it helps

Open file dialog and select a file using WPF controls and C#

Something like that should be what you need

private void button1_Click(object sender, RoutedEventArgs e)
    // Create OpenFileDialog 
    Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();

    // Set filter for file extension and default file extension 
    dlg.DefaultExt = ".png";
    dlg.Filter = "JPEG Files (*.jpeg)|*.jpeg|PNG Files (*.png)|*.png|JPG Files (*.jpg)|*.jpg|GIF Files (*.gif)|*.gif"; 

    // Display OpenFileDialog by calling ShowDialog method 
    Nullable<bool> result = dlg.ShowDialog();

    // Get the selected file name and display in a TextBox 
    if (result == true)
        // Open document 
        string filename = dlg.FileName;
        textBox1.Text = filename;

Converting int to string in C

char string[something];
sprintf(string, "%d", 42);

How to create a inner border for a box in html?

  1. Use dashed border style for outline.
  2. Draw background-color with :before or :after pseudo element.

Note: This method will allow you to have maximum browser support.

Output Image:

Output Image

* {box-sizing: border-box;}_x000D_
.box {_x000D_
  border: 1px dashed #fff;_x000D_
  position: relative;_x000D_
  height: 160px;_x000D_
  width: 350px;_x000D_
  margin: 20px;_x000D_
.box:before {_x000D_
  position: absolute;_x000D_
  background: black;_x000D_
  content: '';_x000D_
  bottom: -10px;_x000D_
  right: -10px;_x000D_
  left: -10px;_x000D_
  top: -10px;_x000D_
  z-index: -1;_x000D_
<div class="box">_x000D_

Populating a data frame in R in a loop

You could do it like this:

 iterations = 10
 variables = 2

 output <- matrix(ncol=variables, nrow=iterations)

 for(i in 1:iterations){
  output[i,] <- runif(2)



and then turn it into a data.frame

 output <- data.frame(output)

what this does:

  1. create a matrix with rows and columns according to the expected growth
  2. insert 2 random numbers into the matrix
  3. convert this into a dataframe after the loop has finished.

Installing NumPy and SciPy on 64-bit Windows (with Pip)

Hey I had the same issue.
You can find all the packages in the link below:
And choose the package you need for your version of windows and python.

You have to download the file with whl extension. After that, you will copy the file into your python directory then run the following command:
py -3.6 -m pip install matplotlib-2.1.0-cp36-cp36m-win_amd64.whl

Here is an example when I wanted to install matplolib for my python 3.6
and this is the video I followed.

Execute jar file with multiple classpath libraries from command prompt

You can use maven-assembly-plugin, Here is the example from the official site:

                    <mainClass>your main class</mainClass>
                <id>make-assembly</id> <!-- this is used for inheritance merges -->
                <phase>package</phase> <!-- bind to the packaging phase -->

How to select an element by classname using jqLite?

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

PHP to write Tab Characters inside a file?

The tab character is \t. Notice the use of " instead of '.

$chunk = "abc\tdef\tghi";

PHP Strings - Double quoted

If the string is enclosed in double-quotes ("), PHP will interpret more escape sequences for special characters:


\t horizontal tab (HT or 0x09 (9) in ASCII)

Also, let me recommend the fputcsv() function which is for the purpose of writing CSV files.

Is it valid to have a html form inside another html form?

A non-JavaScript workaround for nesting form tags:

Because you allow for

all fields minus those within "b".

when submitting "a", the following would work, using regular web-forms without fancy JavaScript tricks:

Step 1. Put each form on its own web page.

Step 2. Insert an iframe wherever you want this sub-form to appear.

Step 3. Profit.

I tried to use a code-playground website to show a demo, but many of them prohibit embedding their websites in iframes, even within their own domain.

Exception thrown inside catch block - will it be caught again?

It won't be caught by the second catch block. Each Exception is caught only when inside a try block. You can nest tries though (not that it's a good idea generally):

try {
} catch (IOException) {
   try {
   } catch (IOException e) {
       throw new ApplicationException("Failed twice at doSomething" +
} catch (Exception e) {

Looping over arrays, printing both index and value

users=("kamal" "jamal" "rahim" "karim" "sadia")

for i in ${users[@]}; do
  t=$(( t + 1 ))
  if [ $t -eq 0 ]; then
    for j in ${!users[@]}; do
  echo "${index[$t]} is $i"

Facebook key hash does not match any stored key hashes

In the right side of Android Studio go to Gradle -> Tasks -> android -> signingReport and run it. Copy the SHA-1 key and transform it into base64 using this, and then add the converted base64 hash to your app in the Facebook Developer Console. If you want to use a release hash run this in the command line:keytool -exportcert -alias YOUR_KEYSTORE_ALIAS -keystore YOUR_KEYSTORE | openssl sha1 -binary | openssl base64 Where YOUR_KEYSTORE is the path to the .keystore or .jks that you used as signinConfig for your release variant and YOUR_KEYSTORE_ALIAS is the alias which you gave when you created the keystore. If you do not remember the alias you can run keytool -v -list -keystore YOUR_KEYSTORE and see all the info about the keystore

How do I embed a mp4 movie into my html?

If you have an mp4 video residing at your server, and you want the visitors to stream that over your HTML page.

<video width="480" height="320" controls="controls">
<source src="http://serverIP_or_domain/location_of_video.mp4" type="video/mp4">

Open file by its full path in C++

Normally one uses the backslash character as the path separator in Windows. So:

ifstream file;"C:\\Demo.txt", ios::in);

Keep in mind that when written in C++ source code, you must use the double backslash because the backslash character itself means something special inside double quoted strings. So the above refers to the file C:\Demo.txt.

Python Dictionary contains List as Value - How to update?

Probably something like this:

original_list = dictionary.get('C1')
new_list = []
for item in original_list:
dictionary['C1'] = new_list

What's the difference between a temp table and table variable in SQL Server?

In which scenarios does one out-perform the other?

For smaller tables (less than 1000 rows) use a temp variable, otherwise use a temp table.

Use the XmlInclude or SoapInclude attribute to specify types that are not known statically

Just solved the issue. After digging around for a while longer, I found this SO post which covers the exact same situation. It got me in the right track.

Basically, the XmlSerializer needs to know the default namespace if derived classes are included as extra types. The exact reason why this has to happen is still unknown but, still, serialization is working now.

How to fix 'Object arrays cannot be loaded when allow_pickle=False' for imdb.load_data() function?

Instead of

from keras.datasets import imdb


from tensorflow.keras.datasets import imdb

top_words = 10000
((x_train, y_train), (x_test, y_test)) = imdb.load_data(num_words=top_words, seed=21)

Escape double quotes in Java

Use Java's replaceAll(String regex, String replacement)

For example, Use a substitution char for the quotes and then replace that char with \"

String newstring = String.replaceAll("%","\"");

or replace all instances of \" with \\\"

String newstring = String.replaceAll("\"","\\\"");

How to update one file in a zip archive

I know this is old question, but I wanted to do the same. Update a file in zip archive. And none of the above answers really helped me.

Here is what I did. Created temp directory abc. Copied to abc and extracted the file in that directory. I edited the file I wanted to edit. Then while being in abc, ran the following command

user@host ~/temp/abc $ zip -u
updating: content/js/ (stored 0%)
updating: content/js/moduleConfig.js (deflated 69%)

-u switch will look for changed/new files and will add to the zip archive.

Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated

I had the same issue and resolved by adding "Connection Time" value in web.config file. locate the connectionStrings and add Connection Timeout=3600"

here is the sample

    <add name="MyConn" providerName="System.Data.SqlClient" connectionString="Data Source=MySQLServer;Initial Catalog=MyDB;User ID=sa;Password=123;Connection Timeout=3600" />

offsetting an html anchor to adjust for fixed header

I had been facing a similar issue, unfortunately after implementing all the solutions above, I came to the following conclusion.

  1. My inner elements had a fragile CSS structure and implementing a position relative / absolute play, was completely breaking the page design.
  2. CSS is not my strong suit.

I wrote this simple scrolling js, that accounts for the offset caused due to the header and relocated the div about 125 pixels below. Please use it as you see fit.


<div id="#anchor"></div> <!-- #anchor here is the anchor tag which is on your URL -->

The JavaScript

 $(function() {
  $('a[href*=#]:not([href=#])').click(function() {
    if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'') 
&& location.hostname == this.hostname) {

      var target = $(this.hash);
      target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
      if (target.length) {
          scrollTop: target.offset().top - 125 //offsets for fixed header
        }, 1000);
        return false;
  //Executed on page load with URL containing an anchor tag.
  if($(location.href.split("#")[1])) {
      var target = $('#'+location.href.split("#")[1]);
      if (target.length) {
          scrollTop: target.offset().top - 125 //offset height of header here too.
        }, 1000);
        return false;

See a live implementation here.

SSL Error When installing rubygems, Unable to pull data from '

I had same problem while trying to install cucumber gem. However I noticed that bundler gem already installed with ruby 2.0. I created a Gemfile.rb in the project folder with required gems and followed this steps

  1. Navigate to project folder
  2. Type bundle install

All the required gems installed.

Batch file to perform start, run, %TEMP% and delete all

@echo off
RD %TEMP%\. /S /Q

explorer %temp%

This batch can run from anywhere. RD stands for Remove Directory but this can remove both folders and files which available to delete.

jQuery issue - #<an Object> has no method

This problem can also arise if you include jQuery more than once.

IE11 prevents ActiveX from running

IE displays a active x warning and ask for permission if you allow it to run or not. To overcome this the only solution is to;

  1. Open Internet Explorer.
  2. Click the Tools menu, and then click Internet Options.
  3. On the Security tab, click the Custom level button.
  4. Scroll down the Security Settings list until you see ActiveX controls and plug-ins.
  5. For Automatic prompting for ActiveX controls, click Enable.
  6. Scroll down to Download signed ActiveX controls and click Enable or Prompt.
  7. Scroll down to Run ActiveX controls and plug-ins and click Enable or Prompt.
  8. Scroll down to Script ActiveX controls marked safe for scripting and click Enable or Prompt.
  9. Click OK, and then click OK again.

There is no way to overcome this issue except changing manually Internet explorer settings. Try checking if plugin works fine while changed settings. If its still not working or not showing any warning is display try checking console for other errors which are not related to active x. Good luck!

Retrieving a Foreign Key value with django-rest-framework serializers

Simple solution source='' where category is foreign key and .name it's attribute.

from rest_framework.serializers import ModelSerializer, ReadOnlyField
from my_app.models import Item

class ItemSerializer(ModelSerializer):
    category_name = ReadOnlyField(source='')

    class Meta:
        model = Item
        fields = "__all__"

Maintain image aspect ratio when changing height

No need to add a containing div.

The default for the css "align-items" property is "stretch" which is what is causing your images to be stretched to its full original height. Setting the css "align-items" property to "flex-start" fixes your issue.

.slider {
    display: flex;
    align-items: flex-start;  /* ADD THIS! */

Are there other whitespace codes like &nbsp for half-spaces, em-spaces, en-spaces etc useful in HTML?

There are codes for other space characters, and the codes as such work well, but the characters themselves are legacy character. They have been included into character sets only due to their presence in existing character data, rather than for use in new documents. For some combinations of font and browser version, they may cause a generic glyph of unrepresentable character to be shown. For details, check my page about Unicode spaces.

So using CSS is safer and lets you specify any desired amount of spacing, not just the specific widths of fixed-width spaces. If you just want to have added spacing around your h2 elements, as it seems to me, then setting padding on those elements (changing the value of the padding: 0 settings that you already have) should work fine.

How to disable JavaScript in Chrome Developer Tools?

Update August 2020

  1. Developer Tools (F12)
  2. Click the Gear icon


  1. Should open the Preference tab
  2. Disable Javascript option is on the far right

Disable JS option

Original answer

  1. Developer Tools (F12)
  2. Three vertical dots in upper right
  3. Settings
  4. Under the "Preferences" tab on the left

Preferences section

  1. There will be a "Debugger" section with the option (probably on far right)

Disable check box

Label points in geom_point

The ggrepel package works great for repelling overlapping text labels away from each other. You can use either geom_label_repel() (draws rectangles around the text) or geom_text_repel() functions.


nba <- read.csv("", sep = ",")

nbaplot <- ggplot(nba, aes(x= MIN, y = PTS)) + 
  geom_point(color = "blue", size = 3)

### geom_label_repel
nbaplot + 
  geom_label_repel(aes(label = Name),
                  box.padding   = 0.35, 
                  point.padding = 0.5,
                  segment.color = 'grey50') +

enter image description here

### geom_text_repel
# only label players with PTS > 25 or < 18
# align text vertically with nudge_y and allow the labels to 
# move horizontally with direction = "x"
ggplot(nba, aes(x= MIN, y = PTS, label = Name)) + 
  geom_point(color = dplyr::case_when(nba$PTS > 25 ~ "#1b9e77", 
                                      nba$PTS < 18 ~ "#d95f02",
                                      TRUE ~ "#7570b3"), 
             size = 3, alpha = 0.8) +
  geom_text_repel(data          = subset(nba, PTS > 25),
                  nudge_y       = 32 - subset(nba, PTS > 25)$PTS,
                  size          = 4,
                  box.padding   = 1.5,
                  point.padding = 0.5,
                  force         = 100,
                  segment.size  = 0.2,
                  segment.color = "grey50",
                  direction     = "x") +
  geom_label_repel(data         = subset(nba, PTS < 18),
                  nudge_y       = 16 - subset(nba, PTS < 18)$PTS,
                  size          = 4,
                  box.padding   = 0.5,
                  point.padding = 0.5,
                  force         = 100,
                  segment.size  = 0.2,
                  segment.color = "grey50",
                  direction     = "x") +
  scale_x_continuous(expand = expand_scale(mult = c(0.2, .2))) +
  scale_y_continuous(expand = expand_scale(mult = c(0.1, .1))) +
  theme_classic(base_size = 16)

Edit: To use ggrepel with lines, see this and this.

Created on 2019-05-01 by the reprex package (v0.2.0).

Pandas DataFrame column to list

You can use the Series.to_list method.

For example:

import pandas as pd

df = pd.DataFrame({'a': [1, 3, 5, 7, 4, 5, 6, 4, 7, 8, 9],
                   'b': [3, 5, 6, 2, 4, 6, 7, 8, 7, 8, 9]})



[1, 3, 5, 7, 4, 5, 6, 4, 7, 8, 9]

To drop duplicates you can do one of the following:

>>> df['a'].drop_duplicates().to_list()
[1, 3, 5, 7, 4, 6, 8, 9]
>>> list(set(df['a'])) # as pointed out by EdChum
[1, 3, 4, 5, 6, 7, 8, 9]

How to find out if you're using HTTPS without $_SERVER['HTTPS']

This should always work even when $_SERVER['HTTPS'] is undefined:

function isSecure() {
    (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
    || $_SERVER['SERVER_PORT'] == 443;

The code is compatible with IIS.

From the documentation and user comments :

1) Set to a non-empty value if the script was queried through the HTTPS protocol.

2) Note that when using ISAPI with IIS, the value will be "off" if the request was not made through the HTTPS protocol. (Same behaviour has been reported for IIS7 running PHP as a Fast-CGI application).

Also, Apache 1.x servers (and broken installations) might not have $_SERVER['HTTPS'] defined even if connecting securely. Although not guaranteed, connections on port 443 are, by convention, likely using secure sockets, hence the additional port check.

Additional note: if there is a load balancer between the client and your server, this code doesn't test the connection between the client and the load balancer, but the connection between the load balancer and your server. To test the former connection, you would have to test using the HTTP_X_FORWARDED_PROTO header, but it's much more complex to do; see latest comments below this answer.

How to use switch statement inside a React component?

Try this, which is way cleaner too: Get that switch out of the render in a function and just call it passing the params you want. For example:

renderSwitch(param) {_x000D_
  switch(param) {_x000D_
    case 'foo':_x000D_
      return 'bar';_x000D_
      return 'foo';_x000D_
render() {_x000D_
  return (_x000D_
          // removed for brevity_x000D_
          // removed for brevity_x000D_

Add (insert) a column between two columns in a data.frame

You can do it like below -

df <- data.frame(a=1:4, b=5:8, c=9:12)
df['d'] <- seq(10,13)
df <- df[,c('a','b','d','c')]

How to delete a folder with files using Java

I like this solution the most. It does not use 3rd party library, instead it uses NIO2 of Java 7.

 * Deletes Folder with all of its content
 * @param folder path to folder which should be deleted
public static void deleteFolderAndItsContent(final Path folder) throws IOException {
    Files.walkFileTree(folder, new SimpleFileVisitor<Path>() {
        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
            return FileVisitResult.CONTINUE;

        public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
            if (exc != null) {
                throw exc;
            return FileVisitResult.CONTINUE;

White spaces are required between publicId and systemId

Change the order of statments. For me, changing the block of code




is valid.

Convert string to datetime in

As an alternative, if you put a space between the date and time, DateTime.Parse will recognize the format for you. That's about as simple as you can get it. (If ParseExact was still not being recognized)

Expand Python Search Path to Other Source

You should also read about python packages here:

From your example, I would guess that you really have a package at ~/codez/project. The file in a python directory maps a directory into a namespace. If your subdirectories all have an file, then you only need to add the base directory to your PYTHONPATH. For example:


In addition to testing your PYTHONPATH environment variable, as David explains, you can test it in python like this:

$ python
>>> import project                      # should work if PYTHONPATH set
>>> import sys
>>> for line in sys.path: print line    # print current python path


Is there a way to specify a default property value in Spring XML?

<foo name="port">

should work for you to have 8088 as default port

See also:

Download single files from GitHub

I used the following format, and I feel it's important to inform about the path.

^^^the above is not very complete in my mind<user>/<repoROOTname>/blob/master/<path>/<filename>?raw=true

some said or raw instead of blob, but the 2nd line works for me and I hope will help others...

SQL statement to get column type

For Spark SQL:

DESCRIBE [db_name.]table_name column_name

Alter a MySQL column to be AUTO_INCREMENT

You can apply the atuto_increment constraint to the data column by the following query:


But, if the columns are part of a foreign key constraint you, will most probably receive an error. Therefore, it is advised to turn off foreign_key_checks by using the following query:

SET foreign_key_checks = 0;

Therefore, use the following query instead:

SET foreign_key_checks = 0;
SET foreign_key_checks = 1;

How to set specific window (frame) size in java swing?

Well, you are using both frame.setSize() and frame.pack().

You should use one of them at one time.

Using setSize() you can give the size of frame you want but if you use pack(), it will automatically change the size of the frames according to the size of components in it. It will not consider the size you have mentioned earlier.

Try removing frame.pack() from your code or putting it before setting size and then run it.

How to add shortcut keys for java code in eclipse

I've been Eclipse-free for over a year now, but I believe Eclipse calls these "Templates". Look in your settings for them. You invoke a template by typing its abbreviation and pressing the normal code completion hotkey (ctrl+space by default) or using the Tab key. The standard eclipse shortcut for System.out.println() is "sysout", so "sysout" would do what you want.

Here's another stackoverflow question that has some more details about it: How to use the "sysout" snippet in Eclipse with selected text?

Programmatically Check an Item in Checkboxlist where text is equal to what I want

All Credit to @Jim Scott -- just added one touch. (ASP.NET 4.5 & C#)

Refractoring this a little more... if you pass the CheckBoxList as an object to the method, you can reuse it for any CheckBoxList. Also you can use either the Text or the Value.

private void SelectCheckBoxList(string valueToSelect, CheckBoxList lst)
    ListItem listItem = lst.Items.FindByValue(valueToSelect);
    //ListItem listItem = lst.Items.FindByText(valueToSelect);
    if (listItem != null) listItem.Selected = true;

//How to call it -- in this case from a SQLDataReader and "chkRP" is my CheckBoxList`

SelectCheckBoxList(dr["kRPId"].ToString(), chkRP);`

What's the difference between 'git merge' and 'git rebase'?

Suppose originally there were 3 commits, A,B,C:


Then developer Dan created commit D, and developer Ed created commit E:


Obviously, this conflict should be resolved somehow. For this, there are 2 ways:



Both commits D and E are still here, but we create merge commit M that inherits changes from both D and E. However, this creates diamond shape, which many people find very confusing.



We create commit R, which actual file content is identical to that of merge commit M above. But, we get rid of commit E, like it never existed (denoted by dots - vanishing line). Because of this obliteration, E should be local to developer Ed and should have never been pushed to any other repository. Advantage of rebase is that diamond shape is avoided, and history stays nice straight line - most developers love that!

Dynamic function name in javascript?

If you want to have a dynamic function like the __call function in PHP, you could use Proxies.

const target = {};

const handler = {
  get: function (target, name) {
    return (myArg) => {
      return new Promise(resolve => setTimeout(() => resolve('some' + myArg), 600))

const proxy = new Proxy(target, handler);

(async function() {
  const result = await'string')
  console.log('result', result) // 'result somestring' after 600 ms

UITextField text change event

From proper way to do uitextfield text change call back:

I catch the characters sent to a UITextField control something like this:

// Add a "textFieldDidChange" notification method to the text field control.

In Objective-C:

[textField addTarget:self 

In Swift:

textField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)

Then in the textFieldDidChange method you can examine the contents of the textField, and reload your table view as needed.

You could use that and put calculateAndUpdateTextFields as your selector.

How to install a Python module via its in Windows? is designed to be run from the command line. You'll need to open your command prompt (In Windows 7, hold down shift while right-clicking in the directory with the file. You should be able to select "Open Command Window Here").

From the command line, you can type

python --help get a list of commands. What you are looking to do is...

python install

How to remove a variable from a PHP session array

If you want to remove or unset all $_SESSION 's then try this


If you want to remove specific $_SESSION['name'] then try this


Remove Unnamed columns in pandas dataframe

First, find the columns that have 'unnamed', then drop those columns. Note: You should Add inplace = True to the .drop parameters as well.

df.drop(df.columns[df.columns.str.contains('unnamed',case = False)],axis = 1, inplace = True)