Programs & Examples On #Cgfloat

Figure out size of UILabel based on String in Swift

This solution will help to calculate the height and width at runtime.

    let messageText = "Your Text String"
    let size = CGSize.init(width: 250, height: 1000)
    let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
    let estimateFrame = NSString(string: messageText).boundingRect(with:  size, options: options, attributes: [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue", size: 17)!], context: nil)

Here you can calculate the estimated height that your string would take and pass it to the UILabel frame.


unable to dequeue a cell with identifier Cell - must register a nib or a class for the identifier or connect a prototype cell in a storyboard

If you defined your cell through the Interface Builder, by placing a cell inside your UICollectionView, or UITableView :

Make sure you binded the cell with an actual class you created, and very important, that you checked "Inherit module from target"

How to set cell spacing and UICollectionView - UICollectionViewFlowLayout size ratio?

For Swift 3 and XCode 8, this worked. Follow below steps to achieve this:-

        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
        var width = UIScreen.main.bounds.width
        layout.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
    width = width - 10
    layout.itemSize = CGSize(width: width / 2, height: width / 2)
        layout.minimumInteritemSpacing = 0
        layout.minimumLineSpacing = 0
        collectionView!.collectionViewLayout = layout

swift UITableView set rowHeight

yourTableView.rowHeight = UITableViewAutomaticDimension

Try this.

Adjust UILabel height to text

I have strong working solution.

in layoutSubviews:

    _title.frame = CGRect(x: 0, y: 0, width: bounds.width, height: 0)
    _title.frame.size = _title.bounds.size

in text setter:

    _title.text = newValue

UPD. of course with this UILabel settings:

    _title.lineBreakMode = .ByWordWrapping
    _title.numberOfLines = 0

How do I concatenate or merge arrays in Swift?

var arrayOne = [1,2,3]
var arrayTwo = [4,5,6]

if you want result as : [1,2,3,[4,5,6]]


above code will convert arrayOne as a single element and add it to the end of arrayTwo.

if you want result as : [1, 2, 3, 4, 5, 6] then,

arrayOne.append(contentsOf: arrayTwo)

above code will add all the elements of arrayOne at the end of arrayTwo.


self.tableView.reloadData() not working in Swift

I was also facing the same issue, what I did wrong was that I'd forgot to add

tableView.delegate = self    
tableView.dataSource = self

in the viewDidLoad() {} method. This could be one reason of self.tableView.reloadData() not working.

Swift: Determine iOS Screen size

In Swift 3.0

let screenSize = UIScreen.main.bounds
let screenWidth = screenSize.width
let screenHeight = screenSize.height

In older swift: Do something like this:

let screenSize: CGRect = UIScreen.mainScreen().bounds

then you can access the width and height like this:

let screenWidth = screenSize.width
let screenHeight = screenSize.height

if you want 75% of your screen's width you can go:

let screenWidth = screenSize.width * 0.75

Swift 4.0

// Screen width.
public var screenWidth: CGFloat {
    return UIScreen.main.bounds.width

// Screen height.
public var screenHeight: CGFloat {
    return UIScreen.main.bounds.height

In Swift 5.0

let screenSize: CGRect = UIScreen.main.bounds

Changing Font Size For UITableView Section Headers

While mosca1337's answer is a correct solution, be careful with that method. For a header with text longer than one line, you will have to perform the calculations of the height of the header in tableView:heightForHeaderInSection: which can be cumbersome.

A much preferred method is to use the appearance API:

[[UILabel appearanceWhenContainedIn:[UITableViewHeaderFooterView class], nil] setFont:[UIFont boldSystemFontOfSize:28]];

This will change the font, while still leaving the table to manage the heights itself.

For optimal results, subclass the table view, and add it to the containment chain (in appearanceWhenContainedIn:) to make sure the font is only changed for the specific table views.

How to hide first section header in UITableView (grouped style)

I have a workaround that seems reasonably clean to me. So I'm answering my own question.

Since 0 as the first section header's height doesn't work, I return 1. Then I use the contentInset to hide that height underneath the navigation bar.


- (CGFloat) tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
    if (section == 0)
            return 1.0f;
    return 32.0f;

- (NSString*) tableView:(UITableView *) tableView titleForHeaderInSection:(NSInteger)section
    if (section == 0) {
        return nil;
    } else {
        // return some string here ...

- (void) viewDidLoad
    [super viewDidLoad];

     self.tableView.contentInset = UIEdgeInsetsMake(-1.0f, 0.0f, 0.0f, 0.0);


override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return section == 0 ? 1.0 : 32

override func viewDidLoad() {

    tableView.contentInset = UIEdgeInsets(top: -1, left: 0, bottom: 0, right: 0)

UITableView with fixed section headers

The headers only remain fixed when the UITableViewStyle property of the table is set to UITableViewStylePlain. If you have it set to UITableViewStyleGrouped, the headers will scroll up with the cells.

Cell spacing in UICollectionView

Swift 3 Version

Simply create a UICollectionViewFlowLayout subclass and paste this method.

override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        guard let answer = super.layoutAttributesForElements(in: rect) else { return nil }

        for i in 1..<answer.count {
            let currentAttributes = answer[i]
            let previousAttributes = answer[i - 1]

            let maximumSpacing: CGFloat = 8
            let origin = previousAttributes.frame.maxX

            if (origin + maximumSpacing + currentAttributes.frame.size.width < self.collectionViewContentSize.width && currentAttributes.frame.origin.x > previousAttributes.frame.origin.x) {
                var frame = currentAttributes.frame
                frame.origin.x = origin + maximumSpacing
                currentAttributes.frame = frame

        return answer

Creating a UITableView Programmatically

sample table

 #import "StartreserveViewController.h"
 #import "CollectionViewController.h"
 #import "TableViewCell1.h"
@interface StartreserveViewController ()

NSArray *name;
NSArray *images;
NSInteger selectindex;



@implementation StartreserveViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.

self.view.backgroundColor = [UIColor blueColor];
_startReservetable.backgroundColor = [UIColor blueColor];

name = [[NSArray alloc]initWithObjects:@"Mobiles",@"Costumes",@"Shoes", 
images = [[NSArray 


 - (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.

pragma mark - UiTableview Datasource

 -(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
return 1;

 -(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:
return 3;

 - (UITableViewCell *)tableView:(UITableView *)tableView 
  cellForRowAtIndexPath:(NSIndexPath *)indexPath

static NSString *cellId = @"tableview";

TableViewCell1  *cell =[tableView dequeueReusableCellWithIdentifier:cellId];

cell.cellTxt .text = [name objectAtIndex:indexPath.row];

cell.cellImg.image = [UIImage imageNamed:[images 

return cell;


-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:
(NSIndexPath *)indexPath
selectindex = indexPath.row;
[self performSegueWithIdentifier:@"second" sender:self];

   #pragma mark - Navigation

 // In a storyboard-based application, you will often want to do a little     
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

if ([segue.identifier isEqualToString:@"second"])

    CollectionViewController *obj = segue.destinationViewController;
           obj.receivename = [name objectAtIndex:selectindex];


// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.



#import <UIKit/UIKit.h>

@interface StartreserveViewController :      
@property (strong, nonatomic) IBOutlet UITableView *startReservetable;


NSAttributedString add text alignment

[averagRatioArray addObject:[NSString stringWithFormat:@"When you respond Yes to %@ the average response to    %@ was %0.02f",QString1,QString2,M1]];
[averagRatioArray addObject:[NSString stringWithFormat:@"When you respond No  to %@ the average response to    %@ was %0.02f",QString1,QString2,M0]];

UIFont *font2 = [UIFont fontWithName:@"Helvetica-Bold" size:15];
UIFont *font = [UIFont fontWithName:@"Helvetica-Bold" size:12];

NSMutableAttributedString *str=[[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"When you respond Yes to %@ the average response to %@ was",QString1,QString2]];
[str addAttribute:NSFontAttributeName value:font range:NSMakeRange(0,[@"When you respond Yes to " length])];
[str addAttribute:NSFontAttributeName value:font2 range:NSMakeRange([@"When you respond Yes to " length],[QString1 length])];
[str addAttribute:NSFontAttributeName value:font range:NSMakeRange([QString1 length],[@" the average response to " length])];
[str addAttribute:NSFontAttributeName value:font2 range:NSMakeRange([@" the average response to " length],[QString2 length])];
[str addAttribute:NSFontAttributeName value:font range:NSMakeRange([QString2 length] ,[@" was" length])];
// [str addAttribute:NSFontAttributeName value:font2 range:NSMakeRange(49+[QString1 length]+[QString2 length] ,8)];
[averagRatioArray addObject:[NSString stringWithFormat:@"%@",str]];

How to set the height of table header in UITableView?

In case you still need it, have you tried to set the property


If you calculate the heigh you need, and set a new view for tableHeaderView:

CGRect frame = self.tableView.tableHeaderView.frame;
frame.size.height = newHeight;

self.tableView.tableHeaderView = [[UIView alloc] initWithFrame:frame];

It should work.

UITableView, Separator color where to set?

- (void)viewDidLoad
   [self.tableView setSeparatorColor:[UIColor myColor]];

I hope that helps - you'll need the self. to access it, remember.

Swift 4.2

tableView.separatorColor =

UIImage resize (Scale proportion)

This fixes the math to scale to the max size in both width and height rather than just one depending on the width and height of the original.

- (UIImage *) scaleProportionalToSize: (CGSize)size
    float widthRatio = size.width/self.size.width;
    float heightRatio = size.height/self.size.height;

    if(widthRatio > heightRatio)
    } else {

    return [self scaleToSize:size];

How to Rotate a UIImage 90 degrees?

Rotate Image by 90 degree (clockwise/anti-clockwise direction)

Function call -

 UIImage *rotatedImage = [self rotateImage:originalImage clockwise:YES];


- (UIImage*)rotateImage:(UIImage*)sourceImage clockwise:(BOOL)clockwise
    CGSize size = sourceImage.size;
    UIGraphicsBeginImageContext(CGSizeMake(size.height, size.width));
    [[UIImage imageWithCGImage:[sourceImage CGImage]
                   orientation:clockwise ? UIImageOrientationRight : UIImageOrientationLeft]
                   drawInRect:CGRectMake(0,0,size.height ,size.width)];

   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();

   return newImage;

What's the difference between using CGFloat and float?

CGFloat is a regular float on 32-bit systems and a double on 64-bit systems

typedef float CGFloat;// 32-bit
typedef double CGFloat;// 64-bit

So you won't get any performance penalty.

Setting custom UITableViewCells height

If all your rows are the same height, just set the rowHeight property of the UITableView rather than implementing the heightForRowAtIndexPath. Apple Docs:

There are performance implications to using tableView:heightForRowAtIndexPath: instead of rowHeight. Every time a table view is displayed, it calls tableView:heightForRowAtIndexPath: on the delegate for each of its rows, which can result in a significant performance problem with table views having a large number of rows (approximately 1000 or more).

Resize image in the wiki of GitHub using Markdown

I have used methods described above. Now I am using the method which is a way similiar but more simple to me.

  1. First create add file to your project.
  2. Then upload screenshoots or whatever description images needed to your project main directory.
  3. After uploading image Assets use html to refer these assets directly without using link like below

Like this:

<img src="icon.jpg" width="324" height="324">

<p align="center">
  <img src="screen1.png" width="256" height="455">
  <img src="screen2.png" width="256" height="455">
  <img src="screen3.png" width="256" height="455">

On above example I have used paragraph to align images side by side. If you are going to use single image just use the code as below

<img src="icon.jpg" width="324" height="324">

Have a nice day!

Split string by single spaces

Can you use boost?

samm$ cat
#include <boost/algorithm/string/classification.hpp>
#include <boost/algorithm/string/split.hpp>

#include <boost/foreach.hpp>

#include <iostream>
#include <string>
#include <vector>

    std::string split_me( "hello world  how are   you" );

    typedef std::vector<std::string> Tokens;
    Tokens tokens;
    boost::split( tokens, split_me, boost::is_any_of(" ") );

    std::cout << tokens.size() << " tokens" << std::endl;
    BOOST_FOREACH( const std::string& i, tokens ) {
        std::cout << "'" << i << "'" << std::endl;

sample execution:

samm$ ./a.out
8 tokens

how to send multiple data with $.ajax() jquery

you can use FormData

take look at my snippet from MVC

var fd = new FormData();
fd.append("ProfilePicture", $("#mydropzone")[0].files[0]);// getting value from form feleds 
d.append("id", @(((User) Session["User"]).ID));// getting value from session

    url: '@Url.Action("ChangeUserPicture", "User")',
    dataType: "json",
    data: fd,//here is your data
    processData: false,
    contentType: false,
    type: 'post',
    success: function(data) {},

Can I mask an input text in a bat file?

If the lack of source code bothers you, I have another alternative.

@echo off
for /f "delims=" %%p in ('ReadLine -h -p "Enter password: "') do set PWD=%%p
echo You entered: %PWD%

You can get it from Source code is included.

Change value of input placeholder via model?

Since AngularJS does not have directive DOM manipulations as jQuery does, a proper way to modify attributes of one element will be using directive. Through link function of a directive, you have access to both element and its attributes.

Wrapping you whole input inside one directive, you can still introduce ng-model's methods through controller property.

This method will help to decouple the logic of ngmodel with placeholder from controller. If there is no logic between them, you can definitely go as Wagner Francisco said.

Get the cell value of a GridView row

string id;
foreach (GridViewRow rows in grd.Rows)
   TextBox lblStrucID = (TextBox)rows.FindControl("grdtext");

How to get request url in a jQuery $.get/ajax request

I can't get it to work on $.get() because it has no complete event.

I suggest to use $.ajax() like this,

    url: '',
    data: {'a':1,'b':2,'c':3},
    dataType: 'xml',
    complete : function(){
    success: function(xml){

craz demo

Pass form data to another page with php

The best way to accomplish that is to use POST which is a method of Hypertext Transfer Protocol



<form action="site2.php" method="post">
Name: <input type="text" name="name">
Email: <input type="text" name="email">
<input type="submit">




 Hello <?php echo $_POST["name"]; ?>!<br>
 Your mail is <?php echo $_POST["mail"]; ?>.



Hello "name" !

Your email is "[email protected]" .

how to set radio button checked in edit mode in MVC razor view

Here is how I do it and works both for create and edit:

//How to do it with enums
<div class="editor-field">
   @Html.RadioButtonFor(x => x.gender, (int)Gender.Male) Male
   @Html.RadioButtonFor(x => x.gender, (int)Gender.Female) Female

//And with Booleans
<div class="editor-field">
   @Html.RadioButtonFor(x => x.IsMale, true) Male
   @Html.RadioButtonFor(x => x.IsMale, false) Female

the provided values (true and false) are the values that the engine will render as the values for the html element i.e.:

<input id="IsMale" type="radio" name="IsMale" value="True">
<input id="IsMale" type="radio" name="IsMale" value="False">

And the checked property is dependent on the Model.IsMale value.

Razor engine seems to internally match the set radio button value to your model value, if a proper from and to string convert exists for it. So there is no need to add it as an html attribute in the helper method.

What do the result codes in SVN mean?

Take a look in the Subversion Book reference: "Status of working copy files and directories"

Highly recommended for anyone doing pretty much anything with SVN.

IIS Config Error - This configuration section cannot be used at this path

Heres what worked for me, had a similar problem on my new laptop which had windows 10.

  • Search for "Turn windows features on or off"
  • Check "Internet Information Services"
  • Check "World Wide Web Services"
  • Check "Application Development Features"
  • Enable all items under this

try again, now it should work.

How to solve java.lang.OutOfMemoryError trouble in Android

android:largeHeap="true" didn't fix the error

In my case, I got this error after I added an icon/image to Drawable folder by converting SVG to vector. Simply, go to the icon xml file and set small numbers for the width and height


How to pause for specific amount of time? (Excel/VBA)

Use the Wait method:

Application.Wait Now + #0:00:01#

or (for Excel 2010 and later):

Application.Wait Now + #12:00:01 AM#

Difference between using "chmod a+x" and "chmod 755"

chmod a+x modifies the argument's mode while chmod 755 sets it. Try both variants on something that has full or no permissions and you will notice the difference.

Map and Reduce in .NET

Since I never can remember that LINQ calls it Where, Select and Aggregate instead of Filter, Map and Reduce so I created a few extension methods you can use:

IEnumerable<string> myStrings = new List<string>() { "1", "2", "3", "4", "5" };
IEnumerable<int> convertedToInts = myStrings.Map(s => int.Parse(s));
IEnumerable<int> filteredInts = convertedToInts.Filter(i => i <= 3); // Keep 1,2,3
int sumOfAllInts = filteredInts.Reduce((sum, i) => sum + i); // Sum up all ints
Assert.Equal(6, sumOfAllInts); // 1+2+3 is 6

Here are the 3 methods (from ):

public static IEnumerable<R> Map<T, R>(this IEnumerable<T> self, Func<T, R> selector) {
    return self.Select(selector);

public static T Reduce<T>(this IEnumerable<T> self, Func<T, T, T> func) {
    return self.Aggregate(func);

public static IEnumerable<T> Filter<T>(this IEnumerable<T> self, Func<T, bool> predicate) {
    return self.Where(predicate);

Some more details from :

enter image description here

how do I initialize a float to its max/min value?

You can use std::numeric_limits which is defined in <limits> to find the minimum or maximum value of types (As long as a specialization exists for the type). You can also use it to retrieve infinity (and put a - in front for negative infinity).

#include <limits>



As noted in the comments, min() returns the lowest possible positive value. In other words the positive value closest to 0 that can be represented. The lowest possible value is the negative of the maximum possible value.

There is of course the std::max_element and min_element functions (defined in <algorithm>) which may be a better choice for finding the largest or smallest value in an array.

Git push existing repo to a new and different remote repo server?

If you have Existing Git repository:

cd existing_repo
git remote rename origin old-origin
git remote add origin
git push -u origin --all
git push -u origin --tags

How can I count the number of elements of a given value in a matrix?

Use nnz instead of sum. No need for the double call to collapse matrices to vectors and it is likely faster than sum.

nnz(your_matrix == 5)


Can we overload the main method in Java?

Yes. 'main( )' method can be overloaded. I have tried to put in some piece of code to answer your question.

public class Test{
static public void main( String [] args )
                System.out.println( "In the JVMs static main" );
                main( 5, 6, 7 );    //Calling overloaded static main method
                Test t = new Test( );
                String [] message  = { "Subhash", "Loves", "Programming" };
                t.main( 6, message );

        public static void main( int ... args )
                System.out.println( "In the static main called by JVM's main" );
                for( int val : args )
                        System.out.println( val );

        public void main( int x )
                System.out.println( "1: In the overloaded  non-static main with int with value " + x );

        public void main( int x, String [] args )
                System.out.println( "2: In the overloaded  non-static main with int with value " + x );
                for ( String val : args )
                        System.out.println( val );


$ java Test
In the JVMs static main
In the static main called by JVM's main
1: In the overloaded  non-static main with int with value 5
2: In the overloaded  non-static main with int with value 6

In the above code, both static-method as well as a non-static version of main methods are overloaded for demonstration purpose. Note that, by writing JVMs main, I mean to say, it is the main method that JVM uses first to execute a program.

How to trigger a phone call when clicking a link in a web page on mobile phone

Clickable smartphone link code:

The following link can be used to make a clickable phone link. You can copy the code below and paste it into your webpage, then edit with your phone number. This code may not work on all phones but does work for iPhone, Droid / Android, and Blackberry.

<a href="tel:1-847-555-5555">1-847-555-5555</a>

Phone number links can be used with the dashes, as shown above, or without them as well as in the following example:

<a href="tel:18475555555">1-847-555-5555</a>

It is also possible to use any text in the link as long as the phone number is set up with the "tel:18475555555" as in this example:

<a href="tel:18475555555">Click Here To Call Support 1-847-555-5555</a>

Below is a clickable telephone hyperlink you can check out. In most non-phone browsers this link will give you a "The webpage cannot be displayed" error or nothing will happen.

NOTE: The iPhone Safari browser will automatically detect a phone number on a page and will convert the text into a call link without using any of the code on this page.

WTAI smartphone link code: The WTAI or "Wireless Telephony Application Interface" link code is shown below. This code is considered to be the correct mobile phone protocol and will work on smartphones like Droid, however, it may not work for Apple Safari on iPhone and the above code is recommended.

<a href="wtai://wp/mc;18475555555">Click Here To Call Support 1-847-555-5555</a> 

Submit button doesn't work

I faced this problem today, and the issue was I was preventing event default action in document onclick:

document.onclick = function(e) {

Document onclick usually is used for event delegation but it's wrong to prevent default for every event, you must do it only for required elements:

document.onclick = function(e) {
    if ( instanceof HTMLAnchorElement) e.preventDefault();

What does this error mean: "error: expected specifier-qualifier-list before 'type_name'"?

I was able to sort this out using Gorgando's fix, but instead of moving imports away, I commented each out individually, built the app, then edited accordingly until I got rid of them.

How to iterate over a std::map full of strings in C++

Your main problem is that you are calling a method called first() in the iterator. What you are meant to do is use the property called first:

...append(iter->first) rather than ...append(iter->first())

As a matter of style, you shouldn't be using new to create that string.

std::string something::toString() 
        std::map<std::string, std::string>::iterator iter;
        std::string strToReturn; //This is no longer on the heap

        for (iter = table.begin(); iter != table.end(); ++iter) {
           strToReturn.append(iter->first); //Not a method call
           // Make sure you don't modify table here or the iterators will not work as you expect
        return strToReturn;

edit: facildelembrar pointed out (in the comments) that in modern C++ you can now rewrite the loop

for (auto& item: table) {

Sanitizing user input before adding it to the DOM in Javascript

Never use escape(). It's nothing to do with HTML-encoding. It's more like URL-encoding, but it's not even properly that. It's a bizarre non-standard encoding available only in JavaScript.

If you want an HTML encoder, you'll have to write it yourself as JavaScript doesn't give you one. For example:

function encodeHTML(s) {
    return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/"/g, '&quot;');

However whilst this is enough to put your user_id in places like the input value, it's not enough for id because IDs can only use a limited selection of characters. (And % isn't among them, so escape() or even encodeURIComponent() is no good.)

You could invent your own encoding scheme to put any characters in an ID, for example:

function encodeID(s) {
    if (s==='') return '_';
    return s.replace(/[^a-zA-Z0-9.-]/g, function(match) {
        return '_'+match[0].charCodeAt(0).toString(16)+'_';

But you've still got a problem if the same user_id occurs twice. And to be honest, the whole thing with throwing around HTML strings is usually a bad idea. Use DOM methods instead, and retain JavaScript references to each element, so you don't have to keep calling getElementById, or worrying about how arbitrary strings are inserted into IDs.


function addChut(user_id) {
    var log= document.createElement('div');
    log.className= 'log';
    var textarea= document.createElement('textarea');
    var input= document.createElement('input');
    input.value= user_id;
    input.readonly= True;
    var button= document.createElement('input');
    button.type= 'button';
    button.value= 'Message';

    var chut= document.createElement('div');
    chut.className= 'chut';

    button.onclick= function() {
        alert('Send '+textarea.value+' to '+user_id);

    return chut;

You could also use a convenience function or JS framework to cut down on the lengthiness of the create-set-appends calls there.


I'm using jQuery at the moment as a framework

OK, then consider the jQuery 1.4 creation shortcuts, eg.:

var log= $('<div>', {className: 'log'});
var input= $('<input>', {readOnly: true, val: user_id});

The problem I have right now is that I use JSONP to add elements and events to a page, and so I can not know whether the elements already exist or not before showing a message.

You can keep a lookup of user_id to element nodes (or wrapper objects) in JavaScript, to save putting that information in the DOM itself, where the characters that can go in an id are restricted.

var chut_lookup= {};

function getChut(user_id) {
    var key= '_map_'+user_id;
    if (key in chut_lookup)
        return chut_lookup[key];
    return chut_lookup[key]= addChut(user_id);

(The _map_ prefix is because JavaScript objects don't quite work as a mapping of arbitrary strings. The empty string and, in IE, some Object member names, confuse it.)

Pandas rename column by position?

You can do this:

df.rename(columns={ df.columns[1]: "whatever" })

Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE] even if app appears to not be installed

Using Ionic with Cordova via command line...

ionic cordova run android --prod

I ran into this and found that I had deleted the release version from a previous test install, but had an old debug version that was hanging out in apps drawer that I missed. I unplugged my device from the computer, opened the app drawer and used "Search apps.." to find all instances of the app to uninstall them. Then I re-plugged in the device to the computer and viola, it worked!

Thanks for the help everyone!

Bootstrap $('#myModal').modal('show') is not working

jQuery lib has to be loaded first. In my case, i was loading bootstrap lib first, also tried tag with target and firing a click trigger. But the main issue was - jquery has to be loaded first.

How should I log while using multiprocessing in Python?

For whoever might need this, I wrote a decorator for multiprocessing_logging package that adds the current process name to logs, so it becomes clear who logs what.

It also runs install_mp_handler() so it becomes unuseful to run it before creating a pool.

This allows me to see which worker creates which logs messages.

Here's the blueprint with an example:

import sys
import logging
from functools import wraps
import multiprocessing
import multiprocessing_logging

# Setup basic console logger as 'logger'
logger = logging.getLogger()
console_handler = logging.StreamHandler(sys.stdout)
console_handler.setFormatter(logging.Formatter(u'%(asctime)s :: %(levelname)s :: %(message)s'))

# Create a decorator for functions that are called via multiprocessing pools
def logs_mp_process_names(fn):
    class MultiProcessLogFilter(logging.Filter):
        def filter(self, record):
                process_name = multiprocessing.current_process().name
            except BaseException:
                process_name = __name__
            record.msg = f'{process_name} :: {record.msg}'
            return True

    f = MultiProcessLogFilter()

    # Wraps is needed here so apply / apply_async know the function name
    def wrapper(*args, **kwargs):
        return fn(*args, **kwargs)

    return wrapper

# Create a test function and decorate it
def test(argument):'test function called via: {argument}')

# You can also redefine undecored functions
def undecorated_function():'I am not decorated')

def redecorated(*args, **kwargs):
    return undecorated_function(*args, **kwargs)

# Enjoy
if __name__ == '__main__':
    with multiprocessing.Pool() as mp_pool:
        # Also works with apply_async
        mp_pool.apply(test, ('mp pool',))
        mp_pool.apply(redecorated)'some main logs')
        test('main program')

Making view resize to its parent when added with addSubview

that's all you need

childView.frame = parentView.bounds

Fastest way to duplicate an array in JavaScript - slice vs. 'for' loop

In ES6, you can simply utilize the Spread syntax.


let arr = ['a', 'b', 'c'];
let arr2 = [...arr];

Please note that the spread operator generates a completely new array, so modifying one won't affect the other.


arr2.push('d') // becomes ['a', 'b', 'c', 'd']
console.log(arr) // while arr retains its values ['a', 'b', 'c']

How to find out if an item is present in a std::vector?

I use something like this...

#include <algorithm>

template <typename T> 
const bool Contains( std::vector<T>& Vec, const T& Element ) 
    if (std::find(Vec.begin(), Vec.end(), Element) != Vec.end())
        return true;

    return false;

if (Contains(vector,item))
   blah that way it's actually clear and readable. (Obviously you can reuse the template in multiple places).

MVC4 StyleBundle not resolving images

As of v1.1.0-alpha1 (pre release package) the framework uses the VirtualPathProvider to access files rather than touching the physical file system.

The updated transformer can be seen below:

public class StyleRelativePathTransform
    : IBundleTransform
    public void Process(BundleContext context, BundleResponse response)
        Regex pattern = new Regex(@"url\s*\(\s*([""']?)([^:)]+)\1\s*\)", RegexOptions.IgnoreCase);

        response.Content = string.Empty;

        // open each of the files
        foreach (var file in response.Files)
            using (var reader = new StreamReader(file.Open()))
                var contents = reader.ReadToEnd();

                // apply the RegEx to the file (to change relative paths)
                var matches = pattern.Matches(contents);

                if (matches.Count > 0)
                    var directoryPath = VirtualPathUtility.GetDirectory(file.VirtualPath);

                    foreach (Match match in matches)
                        // this is a path that is relative to the CSS file
                        var imageRelativePath = match.Groups[2].Value;

                        // get the image virtual path
                        var imageVirtualPath = VirtualPathUtility.Combine(directoryPath, imageRelativePath);

                        // convert the image virtual path to absolute
                        var quote = match.Groups[1].Value;
                        var replace = String.Format("url({0}{1}{0})", quote, VirtualPathUtility.ToAbsolute(imageVirtualPath));
                        contents = contents.Replace(match.Groups[0].Value, replace);

                // copy the result into the response.
                response.Content = String.Format("{0}\r\n{1}", response.Content, contents);

Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details

<VirtualHost *:80>
    ServerName www.YOURDOMAIN.COM
    ServerAlias YOURDOMAIN.COM
    DocumentRoot /var/www/YOURDOMAIN.COM/public_html
    ErrorLog /var/www/YOURDOMAIN.COM/error.log
    CustomLog /var/www/YOURDOMAIN.COM/requests.log combined

    DocumentRoot /var/www/YOURDOMAIN.COM/public_html
    <Directory />
        Options FollowSymLinks
        AllowOverride None
    <Directory /var/www/YOURDOMAIN.COM/public_html>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        Order allow,deny
        allow from all


How to determine device screen size category (small, normal, large, xlarge) using code?

In 2018, if you need Jeff's answer in Kotlin, here it is:

  private fun determineScreenSize(): String {
    // Thanks to
    val screenLayout = resources.configuration.screenLayout
    return when {
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_SMALL -> "Small"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_NORMAL -> "Normal"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_LARGE -> "Large"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_XLARGE -> "Xlarge"
      screenLayout and Configuration.SCREENLAYOUT_SIZE_MASK == Configuration.SCREENLAYOUT_SIZE_UNDEFINED -> "Undefined"
      else -> error("Unknown screenLayout: $screenLayout")

Center align "span" text inside a div

If you know the width of the span you could just stuff in a left margin.

Try this:

.center { text-align: center} span { display: table; }

Add the "center: class to your .

If you want some spans centered, but not others, replace the " span" in your style sheet to a class (e.g "center-span") and add that class to the span.

How to set Bullet colors in UL/LI html lists via CSS without using any images or span tags

I know it's a bit of a late answer for this post, but for reference...


ul {
    color: red;

li {
    color: black;

The bullet colour is defined on the ul tag and then we switch the li colour back.

Should composer.lock be committed to version control?

  1. You shouldn't update your dependencies directly on Production.
  2. You should version control your composer.lock file.
  3. You shouldn't version control your actual dependencies.

1. You shouldn't update your dependencies directly on Production, because you don't know how this will affect the stability of your code. There could be bugs introduced with the new dependencies, it might change the way the code behaves affecting your own, it could be incompatible with other dependencies, etc. You should do this in a dev environment, following by proper QA and regression testing, etc.

2. You should version control your composer.lock file, because this stores information about your dependencies and about the dependencies of your dependencies that will allow you to replicate the current state of the code. This is important, because, all your testing and development has been done against specific code. Not caring about the actual version of the code that you have is similar to uploading code changes to your application and not testing them. If you are upgrading your dependencies versions, this should be a willingly act, and you should take the necessary care to make sure everything still works. Losing one or two hours of up time reverting to a previous release version might cost you a lot of money.

One of the arguments that you will see about not needing the composer.lock is that you can set the exact version that you need in your composer.json file, and that in this way, every time someone runs composer install, it will install them the same code. This is not true, because, your dependencies have their own dependencies, and their configuration might be specified in a format that it allows updates to subversions, or maybe even entire versions.

This means that even when you specify that you want Laravel 4.1.31 in your composer.json, Laravel in its composer.json file might have its own dependencies required as Symfony event-dispatcher: 2.*. With this kind of config, you could end up with Laravel 4.1.31 with Symfony event-dispatcher 2.4.1, and someone else on your team could have Laravel 4.1.31 with event-dispatcher 2.6.5, it would all depend on when was the last time you ran the composer install.

So, having your composer.lock file in the version system will store the exact version of this sub-dependencies, so, when you and your teammate does a composer install (this is the way that you will install your dependencies based on a composer.lock) you both will get the same versions.

What if you wanna update? Then in your dev environment run: composer update, this will generate a new composer.lock file (if there is something new) and after you test it, and QA test and regression test it and stuff. You can push it for everyone else to download the new composer.lock, since its safe to upgrade.

3. You shouldn't version control your actual dependencies, because it makes no sense. With the composer.lock you can install the exact version of the dependencies and you wouldn't need to commit them. Why would you add to your repo 10000 files of dependencies, when you are not supposed to be updating them. If you require to change one of this, you should fork it and make your changes there. And if you are worried about having to fetch the actual dependencies each time of a build or release, composer has different ways to alleviate this issue, cache, zip files, etc.

Regular Expression: Any character that is NOT a letter or number

To match anything other than letter or number or letter with diacritics like é you could try this:


And to replace:

var str = 'dfj,dsf7é@lfsd .sdklfàj1';
str = str.replace(/[^\wÀ-úÀ-ÿ]/g, '_');

Inspired by the top post with support for diacritics


Change MySQL default character set to UTF-8 in my.cnf?

MySQL 5.5, all you need is:


collation_server is optional.

mysql> show variables like 'char%';
| Variable_name            | Value                      |
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
8 rows in set (0.00 sec)

OkHttp Post Body as JSON

Another approach is by using FormBody.Builder().
Here's an example of callback:

Callback loginCallback = new Callback() {
    public void onFailure(Call call, IOException e) {
        try {
            Log.i(TAG, "login failed: " + call.execute().code());
        } catch (IOException e1) {

    public void onResponse(Call call, Response response) throws IOException {
        // String loginResponseString = response.body().string();
        try {
            JSONObject responseObj = new JSONObject(response.body().string());
            Log.i(TAG, "responseObj: " + responseObj);
        } catch (JSONException e) {
        // Log.i(TAG, "loginResponseString: " + loginResponseString);

Then, we create our own body:

RequestBody formBody = new FormBody.Builder()
        .add("username", userName)
        .add("password", password)
        .add("customCredential", "")
        .add("isPersistent", "true")
        .add("setCookie", "true")

OkHttpClient client = new OkHttpClient.Builder()
Request request = new Request.Builder()

Finally, we call the server:


Using a dispatch_once singleton model in Swift

In swift, you can create a singleton class following way:

class AppSingleton: NSObject {

    //Shared instance of class
    static let sharedInstance = AppSingleton()

    override init() {

How to retrieve SQL result column value using column name in Python?

import mysql
import mysql.connector

db = mysql.connector.connect(
   host = "localhost",
    user = "root",
    passwd = "P@ssword1",
    database = "appbase"

cursor = db.cursor(dictionary=True)

sql = "select Id, Email from appuser limit 0,1"
result = cursor.fetchone()

# output =>  {'Id': 1, 'Email': '[email protected]'}

# output => 1

# output => [email protected]

Cancel a UIView animation?


#import <QuartzCore/QuartzCore.h>


[myView.layer removeAllAnimations];

How do I run a single test using Jest?

As mentioned in other answers, test.only merely filters out other tests in the same file. So tests in other files would still run.

So to run a single test, there are two approaches:

  • Option 1: If your test name is unique, you can enter t while in watch mode and enter the name of the test you'd like to run.

  • Option 2:

    1. Hit p while in watch mode to enter a regex for the filename you'd like to run. (Relevant commands like this are displayed when you run Jest in watch mode).
    2. Change it to it.only on the test you'd like to run.

With either of the approaches above, Jest will only run the single test in the file you've specified.

How can a add a row to a data frame in R?

To formalize what someone else used setNames for:

add_row <- function(original_data, new_vals_list){ 
  # appends row to dataset while assuming new vals are ordered and classed appropriately. 
  # new_vals must be a list not a single vector. 
    setNames(data.frame(new_vals_list), colnames(original_data))

It preserves class when legal and passes errors elsewhere.

m <- mtcars[ ,1:3]
m$cyl <- as.factor(m$cyl)

#'data.frame':  32 obs. of  3 variables:
# $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
# $ cyl : Factor w/ 3 levels "4","6","8": 2 2 1 2 3 2 3 1 1 2 ...
# $ disp: num  160 160 108 258 360 ...

Factor preserved when adding 4, even though it was passed as a numeric.

str(add_row(m, list(20,4,160)))
#'data.frame':  33 obs. of  3 variables:
# $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
# $ cyl : Factor w/ 3 levels "4","6","8": 2 2 1 2 3 2 3 1 1 2 ... 
# $ disp: num  160 160 108 258 360 ...

Attempting to pass a non- 4,6,8 would return an error that factor level is invalid.

str(add_row(m, list(20,3,160)))
# 'data.frame': 33 obs. of  3 variables:
# $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
# $ cyl : Factor w/ 3 levels "4","6","8": 2 2 1 2 3 2 3 1 1 2 ...
# $ disp: num  160 160 108 258 360 ...
Warning message:
In `[<-.factor`(`*tmp*`, ri, value = 3) :
  invalid factor level, NA generated

How does BitLocker affect performance?

Having used a laptop with BitLocker enabled for almost 2 years now with more or less similar specs (although without the SSD unfortunately), I can say that it really isn't that bad, or even noticable. Although I have not used this particular machine without BitLocker enabled, it really does not feel sluggish at all when compared to my desktop machine (dual core, 16 GB, dual Raptor disks, no BitLocker). Building large projects might take a bit longer, but not enough to notice.

To back this up with more non-scientifical "proof": many of my co-workers used their machines intensively without BitLocker before I joined the company (it became mandatory to use it around the time I joined, even though I am pretty sure the two events are totally unrelated), and they have not experienced noticable performance degradation either.

For me personally, having an "always on" solution like BitLocker beats manual steps for encryption, hands-down. Bitlocker-to-go (new on Windows 7) for USB devices on the other hand is simply too annoying to work with, since you cannot easily exchange information with non-W7 machines. Therefore I use TrueCrypt for removable media.

set gvim font in .vimrc file

When I try:

set guifont=Consolas:h16

I get: Warning: Font "Consolas" reports bad fixed pitch metrics

and the following is work, and don't show the waring.

autocmd vimenter * GuiFont! Consolas:h16

by the way, if you want to use the mouse wheel to control the font-size, then you can add:

function! AdjustFontSize(amount)
    let s:font_size = s:font_size + a:amount
    :execute "GuiFont! Consolas:h" . s:font_size

noremap <C-ScrollWheelUp> :call AdjustFontSize(1)<CR>
noremap <C-ScrollWheelDown> :call AdjustFontSize(-1)<CR>

and if you want to pick the font, you can set

set guifont=*

will bring up a font requester, where you can pick the font you want.

enter image description here

Creating new table with SELECT INTO in SQL

The syntax for creating a new table is

CREATE TABLE new_table
  FROM old_table

This will create a new table named new_table with whatever columns are in old_table and copy the data over. It will not replicate the constraints on the table, it won't replicate the storage attributes, and it won't replicate any triggers defined on the table.

SELECT INTO is used in PL/SQL when you want to fetch data from a table into a local variable in your PL/SQL block.

Bootstrap carousel multiple frames at once

Can this be done with bootstrap 3's carousel? I'm hoping I won't have to go hunting for yet another jQuery plugin

As of 2013-12-08 the answer is no. The effect you are looking for is not possible using Bootstrap 3's generic carousel plugin. However, here's a simple jQuery plugin that seems to do exactly what you want

MySQL JOIN with LIMIT 1 on joined table

When using postgres you can use the DISTINCT ON syntex to limit the number of columns returned from either table.

Here is a sample of the code:

SELECT, c.title, AS product_id, p.title FROM categories AS c JOIN ( SELECT DISTINCT ON( id, p1.title, p1.category_id FROM products p1 ) p ON ( = p.category_id)
The trick is not to join directly on the table with multiple occurrences of the id, rather, first create a table with only a single occurrence for each id

General guidelines to avoid memory leaks in C++

If you are going to manage your memory manually, you have two cases:

  1. I created the object (perhaps indirectly, by calling a function that allocates a new object), I use it (or a function I call uses it), then I free it.
  2. Somebody gave me the reference, so I should not free it.

If you need to break any of these rules, please document it.

It is all about pointer ownership.

How to make a class JSON serializable

Kyle Delaney's comment is correct so i tried to use the answer as well as an improved version of

to create a "JSONAble" mixin.

So to make a class JSON serializeable use "JSONAble" as a super class and either call:




for the two offered methods. You could also extend the JSONAble class with other approaches offered here.

The test example for the Unit Test with Family and Person sample results in:


    "members": {
        "Flintstone,Fred": {
            "firstName": "Fred",
            "lastName": "Flintstone"
        "Flintstone,Wilma": {
            "firstName": "Wilma",
            "lastName": "Flintstone"
    "name": "The Flintstones"


{'name': 'The Flintstones', 'members': {'Flintstone,Fred': {'firstName': 'Fred', 'lastName': 'Flintstone'}, 'Flintstone,Wilma': {'firstName': 'Wilma', 'lastName': 'Flintstone'}}}

Unit Test with Family and Person sample

def testJsonAble(self):
        family=Family("The Flintstones")

class Family(JSONAble):
    def __init__(self,name):
    def add(self,person):

class Person(JSONAble):
    def __init__(self,firstName,lastName):
        self.lastName=lastName; defining JSONAble mixin

Created on 2020-09-03

@author: wf
import json

class JSONAble(object):
    mixin to allow classes to be JSON serializable see

    def __init__(self):
    def toJSON(self):
        return json.dumps(self, default=lambda o: o.__dict__, 
            sort_keys=True, indent=4)
    def getValue(self,v):
        if (hasattr(v, "asJSON")):
            return v.asJSON()
        elif type(v) is dict:
            return self.reprDict(v)
        elif type(v) is list:
            for vitem in v:
            return vlist
            return v
    def reprDict(self,srcDict):
        get my dict elements
        d = dict()
        for a, v in srcDict.items():
        return d
    def asJSON(self):
        recursively return my dict elements
        return self.reprDict(self.__dict__)   

You'll find these approaches now integrated in the project which is available at

SQL LIKE condition to check for integer?

PostgreSQL supports regular expressions matching.

So, your example would look like

SELECT * FROM books WHERE title ~ '^\d+ ?' 

This will match a title starting with one or more digits and an optional space

How to have stored properties in Swift, the same way I had on Objective-C?

So I think I found a method that works cleaner than the ones above because it doesn't require any global variables. I got it from here:

The gist is that you use a struct like so:

extension UIViewController {
    private struct AssociatedKeys {
        static var DescriptiveName = "nsh_DescriptiveName"

    var descriptiveName: String? {
        get {
            return objc_getAssociatedObject(self, &AssociatedKeys.DescriptiveName) as? String
        set {
            if let newValue = newValue {
                    newValue as NSString?,

UPDATE for Swift 2

private struct AssociatedKeys {
    static var displayed = "displayed"

//this lets us check to see if the item is supposed to be displayed or not
var displayed : Bool {
    get {
        guard let number = objc_getAssociatedObject(self, &AssociatedKeys.displayed) as? NSNumber else {
            return true
        return number.boolValue

    set(value) {
        objc_setAssociatedObject(self,&AssociatedKeys.displayed,NSNumber(bool: value),objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)

How to get the fields in an Object via reflection?

You can use Class#getDeclaredFields() to get all declared fields of the class. You can use Field#get() to get the value.

In short:

Object someObject = getItSomehow();
for (Field field : someObject.getClass().getDeclaredFields()) {
    field.setAccessible(true); // You might want to set modifier to public first.
    Object value = field.get(someObject); 
    if (value != null) {
        System.out.println(field.getName() + "=" + value);

To learn more about reflection, check the Sun tutorial on the subject.

That said, the fields does not necessarily all represent properties of a VO. You would rather like to determine the public methods starting with get or is and then invoke it to grab the real property values.

for (Method method : someObject.getClass().getDeclaredMethods()) {
    if (Modifier.isPublic(method.getModifiers())
        && method.getParameterTypes().length == 0
        && method.getReturnType() != void.class
        && (method.getName().startsWith("get") || method.getName().startsWith("is"))
    ) {
        Object value = method.invoke(someObject);
        if (value != null) {
            System.out.println(method.getName() + "=" + value);

That in turn said, there may be more elegant ways to solve your actual problem. If you elaborate a bit more about the functional requirement for which you think that this is the right solution, then we may be able to suggest the right solution. There are many, many tools available to massage javabeans.

byte[] to file in Java

You can try Cactoos:

new LengthOf(new TeeInput(array, new File("a.txt"))).value();

More details:

Why do I get "a label can only be part of a statement and a declaration is not a statement" if I have a variable that is initialized after a label?

This is a quirk of the C grammar. A label (Cleanup:) is not allowed to appear immediately before a declaration (such as char *str ...;), only before a statement (printf(...);). In C89 this was no great difficulty because declarations could only appear at the very beginning of a block, so you could always move the label down a bit and avoid the issue. In C99 you can mix declarations and code, but you still can't put a label immediately before a declaration.

You can put a semicolon immediately after the label's colon (as suggested by Renan) to make there be an empty statement there; this is what I would do in machine-generated code. Alternatively, hoist the declaration to the top of the function:

int main (void) 
    char *str;
    printf("Hello ");
    goto Cleanup;
    str = "World\n";
    printf("%s\n", str);
    return 0;

reading text file with utf-8 encoding using java

I ran into the same problem every time it finds a special character marks it as ??. to solve this, I tried using the encoding: ISO-8859-1

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("txtPath"),"ISO-8859-1"));

while ((line = br.readLine()) != null) {


I hope this can help anyone who sees this post.

Insert Update trigger how to determine if insert or update

I've used those exists (select * from inserted/deleted) queries for a long time, but it's still not enough for empty CRUD operations (when there're no records in inserted and deleted tables). So after researching this topic a little bit I've found more precise solution:

    @columns_count int = ?? -- number of columns in the table,
    @columns_updated_count int = 0

-- this is kind of long way to get number of actually updated columns
-- from columns_updated() mask, it's better to create helper table
-- or at least function in the real system
with cte_columns as (
    select @columns_count as n
    union all
    select n - 1 from cte_columns where n > 1
), cte_bitmasks as (
        (n - 1) / 8 + 1 as byte_number,
        power(2, (n - 1) % 8) as bit_mask
    from cte_columns
    @columns_updated_count = count(*)
from cte_bitmasks as c
    convert(varbinary(1), substring(@columns_updated_mask, c.byte_number, 1)) & c.bit_mask > 0

-- actual check
if exists (select * from inserted)
    if exists (select * from deleted)
        select @operation = 'U'
        select @operation = 'I'
else if exists (select * from deleted)
    select @operation = 'D'
else if @columns_updated_count = @columns_count
    select @operation = 'I'
else if @columns_updated_count > 0
    select @operation = 'U'
    select @operation = 'D'

It's also possible to use columns_updated() & power(2, column_id - 1) > 0 to see if the column is updated, but it's not safe for tables with big number of columns. I've used a bit complex way of calculating (see helpful article below).

Also, this approach will still incorrectly classifies some updates as inserts (if every column in the table is affected by update), and probably it will classifies inserts where there only default values are inserted as deletes, but those are king of rare operations (at lease in my system they are). Besides that, I don't know how to improve this solution at the moment.

How do I redirect output to a variable in shell?

Create a function calling it as the command you want to invoke. In this case, I need to use the ruok command.

Then, call the function and assign its result into a variable. In this case, I am assigning the result to the variable health.

function ruok {
  echo ruok | nc *ip* 2181

health=echo ruok *ip*

How do I check if a string contains another string in Objective-C?

NSString *myString = @"hello bla bla";
NSRange rangeValue = [myString rangeOfString:@"hello" options:NSCaseInsensitiveSearch];

if (rangeValue.length > 0)
    NSLog(@"string contains hello");
    NSLog(@"string does not contain hello!");

//You can alternatively use following too :

if (rangeValue.location == NSNotFound) 
    NSLog(@"string does not contain hello");
    NSLog(@"string contains hello!");

How to build an APK file in Eclipse?

Right click on the project in Eclipse -> Android tools -> Export without signed key. Connect your device. Mount it by sdk/tools.

Round double in two decimal places in C#?

Use an interpolated string, this generates a rounded up string:

var strlen = 6;



JPA: How to get entity based on field value other than ID?

Best practice is using @NaturalId annotation. It can be used as the business key for some cases it is too complicated, so some fields are using as the identifier in the real world. For example, I have user class with user id as primary key, and email is also unique field. So we can use email as our natural id

public class User {
  private int id;

  private String email;

  private String name;

To get our record, just simply use 'session.byNaturalId()'

Session session = sessionFactory.getCurrentSession();
User user = session.byNaturalId(User.class)
                   .using("email","[email protected]")

Using jQuery to compare two arrays of Javascript objects

I was also looking for this today and found:

Don't know if that's a good solution though they do mention some performance considerations taken into account.

I like the idea of a jQuery helper method. @David I'd rather see your compare method to work like:, b)

I doesn't make sense to me to be doing:


where a and b are arrays. Normally when you $(something) you'd be passing a selector string to work with DOM elements.

Also regarding sorting and 'caching' the sorted arrays:

  • I don't think sorting once at the start of the method instead of every time through the loop is 'caching'. The sort will still happen every time you call compare(b). That's just semantics, but...
  • for (var i = 0; t[i]; i++) { ...this loop finishes early if your t array contains a false value in it somewhere, so $([1, 2, 3, 4]).compare([1, false, 2, 3]) returns true!
  • More importantly the array sort() method sorts the array in place, so doing var b = t.sort() ...doesn't create a sorted copy of the original array, it sorts the original array and also assigns a reference to it in b. I don't think the compare method should have side-effects.

It seems what we need to do is to copy the arrays before working on them. The best answer I could find for how to do that in a jQuery way was by none other than John Resig here on SO! What is the most efficient way to deep clone an object in JavaScript? (see comments on his answer for the array version of the object cloning recipe)

In which case I think the code for it would be:

    compare: function (arrayA, arrayB) {
        if (arrayA.length != arrayB.length) { return false; }
        // sort modifies original array
        // (which are passed by reference to our method!)
        // so clone the arrays before sorting
        var a = jQuery.extend(true, [], arrayA);
        var b = jQuery.extend(true, [], arrayB);
        for (var i = 0, l = a.length; i < l; i++) {
            if (a[i] !== b[i]) { 
                return false;
        return true;

var a = [1, 2, 3];
var b = [2, 3, 4];
var c = [3, 4, 2];, b);
// false, c);
// true

// c is still unsorted [3, 4, 2]

"/usr/bin/ld: cannot find -lz"

Others have mentioned that lib32z-dev solves the problem, but in general the required packages can be found here: See "Installing required packages"

How can I use LTRIM/RTRIM to search and replace leading/trailing spaces?

The LTrim function to remove leading spaces and the RTrim function to remove trailing spaces from a string variable. It uses the Trim function to remove both types of spaces and means before and after spaces of string.


Mongoose query where value is not null

total count the documents where the value of the field is not equal to the specified value.

async function getRegisterUser() {
    return Login.count({"role": { $ne: 'Super Admin' }}, (err, totResUser) => {
        if (err) {
            return err;
        return totResUser;

Replace Multiple String Elements in C#

Maybe a little more readable?

    public static class StringExtension {

        private static Dictionary<string, string> _replacements = new Dictionary<string, string>();

        static StringExtension() {
            _replacements["&"] = "and";
            _replacements[","] = "";
            _replacements["  "] = " ";
            // etc...

        public static string clean(this string s) {
            foreach (string to_replace in _replacements.Keys) {
                s = s.Replace(to_replace, _replacements[to_replace]);
            return s;

Also add New In Town's suggestion about StringBuilder...

Get the closest number out of an array

ES6 (ECMAScript 2015) Version:

const counts = [4, 9, 15, 6, 2];
const goal = 5;

const output = counts.reduce((prev, curr) => Math.abs(curr - goal) < Math.abs(prev - goal) ? curr : prev);


For reusability you can wrap in a curry function that supports placeholders ( or This gives lots of flexibility depending on what you need:

const getClosest = _.curry((counts, goal) => {
  return counts.reduce((prev, curr) => Math.abs(curr - goal) < Math.abs(prev - goal) ? curr : prev);

const closestToFive = getClosest(_, 5);
const output = closestToFive([4, 9, 15, 6, 2]);

<script src="[email protected]/lodash.min.js"></script>

Is it possible to program Android to act as physical USB keyboard?

I've modified kernel on Nexus 7 to act like standard HID keyboard and mouse, without losing MTP/ADB/other USB functionality.

You can use usb-gadget-test commandline utility to send keystrokes and mouse movements to your PC. I want to create a remote admin app later, which will send key events and receive video from camera.

Kernel patch, binaries and instructions:

Edit: I've published a proper app to Google Play, if your Nexus 7 is rooted you can flash kernel right from the app, and send keypresses with it.

When do you use varargs in Java?

A good rule of thumb would be:

"Use varargs for any method (or constructor) that needs an array of T (whatever type T may be) as input".

That will make calls to these methods easier (no need to do new T[]{...}).

You could extend this rule to include methods with a List<T> argument, provided that this argument is for input only (ie, the list is not modified by the method).

Additionally, I would refrain from using f(Object... args) because its slips towards a programming way with unclear APIs.

In terms of examples, I have used it in DesignGridLayout, where I can add several JComponents in one call:

layout.row().grid(new JLabel("Label")).add(field1, field2, field3);

In the code above the add() method is defined as add(JComponent... components).

Finally, the implementation of such methods must take care of the fact that it may be called with an empty vararg! If you want to impose at least one argument, then you have to use an ugly trick such as:

void f(T arg1, T... args) {...}

I consider this trick ugly because the implementation of the method will be less straightforward than having just T... args in its arguments list.

Hopes this helps clarifying the point about varargs.

Maven Jacoco Configuration - Exclude classes/packages from report not working

you can configure the coverage exclusion in the sonar properties, outside of the configuration of the jacoco plugin:


and remember to remove the exclusion settings from the plugin

Error: Microsoft Visual C++ 10.0 is required (Unable to find vcvarsall.bat) when running Python script

VS 2010 Express is no longer linked to any VS Express pages (that I found). I did find this link to the ISO which I used and it fixed the errors mentioned here.

Note: Also make sure you have x86 everything (Python + Postgresql) or you'll get other errors. I did not try x64 everything.

How do I check if a given Python string is a substring of another one?

string.find("substring") will help you. This function returns -1 when there is no substring.

Is there a short cut for going back to the beginning of a file by vi editor?

Key in 1 + G and it will take you to the beginning of the file. Converserly, G will take you to the end of the file.

Redirecting from HTTP to HTTPS with PHP

Redirecting from HTTP to HTTPS with PHP on IIS

I was having trouble getting redirection to HTTPS to work on a Windows server which runs version 6 of MS Internet Information Services (IIS). I’m more used to working with Apache on a Linux host so I turned to the Internet for help and this was the highest ranking Stack Overflow question when I searched for “php redirect http to https”. However, the selected answer didn’t work for me.

After some trial and error, I discovered that with IIS, $_SERVER['HTTPS'] is set to off for non-TLS connections. I thought the following code should help any other IIS users who come to this question via search engine.

if (! isset($_SERVER['HTTPS']) or $_SERVER['HTTPS'] == 'off' ) {
    $redirect_url = "https://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    header("Location: $redirect_url");

Edit: From another Stack Overflow answer, a simpler solution is to check if($_SERVER["HTTPS"] != "on").

TypeError: window.initMap is not a function

I have been struggling for several days with this very popular in the last few months issue - "initMap is not a function".

Those two threads helped me:

  1. How to make a callback to Google Maps init in separate files of a web app

  2. Defer attribute doesn't work with Google Maps API?

Why does the map open sometimes and sometimes not. It depends on several factors like speed of connection, environment, etc. Because the initialization function sometimes runs after the google maps API kicks in, that's why the map is not displayed and the browser console throws an error. For me removing only the async attribute fixed the issue. The defer attribute stays.

If async is present: The script is executed asynchronously with the rest of the page (the script will be executed while the page continues the parsing) If async is not present and defer is present: The script is executed when the page has finished parsing If neither async or defer is present: The script is fetched and executed immediately, before the browser continues parsing the page Source -

Hope that helps. Cheers.

C# - How to add an Excel Worksheet programmatically - Office XP / 2003

Another "Up Tick" for AR..., but if you don't have to use interop I would avoid it altogether. This product is actually quite interesting: and it provides a very intuitive, fully managed, api for manipulation excel files and seems to be free. (at least for the time being) SpreadSheetGear is also excellent but pricey.

my two cents.

What is the effect of extern "C" in C++?

Decompile a g++ generated binary to see what is going on


void f() {}
void g();

extern "C" {
    void ef() {}
    void eg();

/* Prevent g and eg from being optimized away. */
void h() { g(); eg(); }

Compile and disassemble the generated ELF output:

g++ -c -std=c++11 -Wall -Wextra -pedantic -o main.o main.cpp
readelf -s main.o

The output contains:

     8: 0000000000000000     7 FUNC    GLOBAL DEFAULT    1 _Z1fv
     9: 0000000000000007     7 FUNC    GLOBAL DEFAULT    1 ef
    10: 000000000000000e    17 FUNC    GLOBAL DEFAULT    1 _Z1hv
    11: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND _GLOBAL_OFFSET_TABLE_
    12: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND _Z1gv
    13: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND eg


We see that:

  • ef and eg were stored in symbols with the same name as in the code

  • the other symbols were mangled. Let's unmangle them:

    $ c++filt _Z1fv
    $ c++filt _Z1hv
    $ c++filt _Z1gv

Conclusion: both of the following symbol types were not mangled:

  • defined
  • declared but undefined (Ndx = UND), to be provided at link or run time from another object file

So you will need extern "C" both when calling:

  • C from C++: tell g++ to expect unmangled symbols produced by gcc
  • C++ from C: tell g++ to generate unmangled symbols for gcc to use

Things that do not work in extern C

It becomes obvious that any C++ feature that requires name mangling will not work inside extern C:

extern "C" {
    // Overloading.
    // error: declaration of C function ‘void f(int)’ conflicts with
    void f();
    void f(int i);

    // Templates.
    // error: template with C linkage
    template <class C> void f(C i) { }

Minimal runnable C from C++ example

For the sake of completeness and for the newbs out there, see also: How to use C source files in a C++ project?

Calling C from C++ is pretty easy: each C function only has one possible non-mangled symbol, so no extra work is required.


#include <cassert>

#include "c.h"

int main() {
    assert(f() == 1);


#ifndef C_H
#define C_H

/* This ifdef allows the header to be used from both C and C++ 
 * because C does not know what this extern "C" thing is. */
#ifdef __cplusplus
extern "C" {
int f();
#ifdef __cplusplus



#include "c.h"

int f(void) { return 1; }


g++ -c -o main.o -std=c++98 main.cpp
gcc -c -o c.o -std=c89 c.c
g++ -o main.out main.o c.o

Without extern "C" the link fails with:

main.cpp:6: undefined reference to `f()'

because g++ expects to find a mangled f, which gcc did not produce.

Example on GitHub.

Minimal runnable C++ from C example

Calling C++ from C is a bit harder: we have to manually create non-mangled versions of each function we want to expose.

Here we illustrate how to expose C++ function overloads to C.


#include <assert.h>

#include "cpp.h"

int main(void) {
    assert(f_int(1) == 2);
    assert(f_float(1.0) == 3);
    return 0;


#ifndef CPP_H
#define CPP_H

#ifdef __cplusplus
// C cannot see these overloaded prototypes, or else it would get confused.
int f(int i);
int f(float i);
extern "C" {
int f_int(int i);
int f_float(float i);
#ifdef __cplusplus



#include "cpp.h"

int f(int i) {
    return i + 1;

int f(float i) {
    return i + 2;

int f_int(int i) {
    return f(i);

int f_float(float i) {
    return f(i);


gcc -c -o main.o -std=c89 -Wextra main.c
g++ -c -o cpp.o -std=c++98 cpp.cpp
g++ -o main.out main.o cpp.o

Without extern "C" it fails with:

main.c:6: undefined reference to `f_int'
main.c:7: undefined reference to `f_float'

because g++ generated mangled symbols which gcc cannot find.

Example on GitHub.

Where is the extern "c" when I include C headers from C++?

Tested in Ubuntu 18.04.

Setting Custom ActionBar Title from Fragment

Google examples tend to use this within the fragments.

private ActionBar getActionBar() {
    return ((ActionBarActivity) getActivity()).getSupportActionBar();

The fragment will belong to an ActionBarActivity and that is where the reference to the actionbar is. This is cleaner because the fragment doesn't need to know exactly what activity it is, it only needs to belong to an activity that implements ActionBarActivity. This makes the fragment more flexible and can be added to multiple activities like they are meant to.

Now, all you need to do in the fragment is.

getActionBar().setTitle("Your Title");

This works well if you have a base fragment that your fragments inherit from instead of the normal fragment class.

public abstract class BaseFragment extends Fragment {
    public ActionBar getActionBar() {
        return ((ActionBarActivity) getActivity()).getSupportActionBar();

Then in your fragment.

public class YourFragment extends BaseFragment {
    public void onActivityCreated(Bundle savedInstanceState) {
        getActionBar().setTitle("Your Title");

How can I count the rows with data in an Excel sheet?

If you want a simple one liner that will do it all for you (assuming by no value you mean a blank cell):

=(ROWS(A:A) + ROWS(B:B) + ROWS(C:C)) - COUNTIF(A:C, "")

If by no value you mean the cell contains a 0

=(ROWS(A:A) + ROWS(B:B) + ROWS(C:C)) - COUNTIF(A:C, 0)

The formula works by first summing up all the rows that are in columns A, B, and C (if you need to count more rows, just increase the columns in the range. E.g. ROWS(A:A) + ROWS(B:B) + ROWS(C:C) + ROWS(D:D) + ... + ROWS(Z:Z)).

Then the formula counts the number of values in the same range that are blank (or 0 in the second example).

Last, the formula subtracts the total number of cells with no value from the total number of rows. This leaves you with the number of cells in each row that contain a value

How to add Apache HTTP API (legacy) as compile-time dependency to build.grade for Android M?

As the answers are a bit old, I will put my solution (what worked for me), it can be helpful for somebody else... I took my solution from the official documentation of Apache, no work-around.

1/ in gradle:

dependencies {
// This is the maintained version from apache.
compile group: '', name: 'httpclient', version: ''

2/ in the rest of the app replace the org.apache.http by and all your imports (dependencies) will be fixed. you can just do ctrl+shift+R and replace it in the whole project.

find if an integer exists in a list of integers

bool vExist = false;
int vSelectValue = 1;

List<int> vList = new List<int>();

IEnumerable vRes = (from n in vListwhere n == vSelectValue);
if (vRes.Count > 0) {
    vExist = true;

Ruby function to remove all white spaces?

s = "I have white space".delete(' ')

And to emulate PHP's trim() function:

s = "   I have leading and trailing white space   ".strip

C++, how to declare a struct in a header file

C++, how to declare a struct in a header file:

Put this in a file called main.cpp:

#include <cstdlib>
#include <iostream>
#include "student.h"

using namespace std;    //Watchout for clashes between std and other libraries

int main(int argc, char** argv) {
    struct Student s1;
    s1.firstName = "fred"; s1.lastName = "flintstone";
    cout << s1.firstName << " " << s1.lastName << endl;
    return 0;

put this in a file named student.h

#ifndef STUDENT_H
#define STUDENT_H

struct Student {
    std::string lastName, firstName;


Compile it and run it, it should produce this output:

s1.firstName = "fred";


You should not place a using namespace std; directive in the C++ header file because you may cause silent name clashes between different libraries. To remedy this, use the fully qualified name: std::string foobarstring; instead of including the std namespace with string foobarstring;.

How does jQuery work when there are multiple elements with the same ID value?

From the id Selector jQuery page:

Each id value must be used only once within a document. If more than one element has been assigned the same ID, queries that use that ID will only select the first matched element in the DOM. This behavior should not be relied on, however; a document with more than one element using the same ID is invalid.

Naughty Google. But they don't even close their <html> and <body> tags I hear. The question is though, why Misha's 2nd and 3rd queries return 2 and not 1 as well.

Convert Unix timestamp to a date string

Other examples here are difficult to remember. At its simplest:

date -r 1305712800

JavaScript override methods

Edit: It's now six years since the original answer was written and a lot has changed!

  • If you're using a newer version of JavaScript, possibly compiled with a tool like Babel, you can use real classes.
  • If you're using the class-like component constructors provided by Angular or React, you'll want to look in the docs for that framework.
  • If you're using ES5 and making "fake" classes by hand using prototypes, the answer below is still as right as it ever was.

Good luck!

JavaScript inheritance looks a bit different from Java. Here is how the native JavaScript object system looks:

// Create a class
function Vehicle(color){
  this.color = color;

// Add an instance method
Vehicle.prototype.go = function(){
  return "Underway in " + this.color;

// Add a second class
function Car(color){
  this.color = color;

// And declare it is a subclass of the first
Car.prototype = new Vehicle();

// Override the instance method
Car.prototype.go = function(){
  return + " car"

// Create some instances and see the overridden behavior.
var v = new Vehicle("blue");
v.go() // "Underway in blue"

var c = new Car("red");
c.go() // "Underway in red car"

Unfortunately this is a bit ugly and it does not include a very nice way to "super": you have to manually specify which parent classes' method you want to call. As a result, there are a variety of tools to make creating classes nicer. Try looking at Prototype.js, Backbone.js, or a similar library that includes a nicer syntax for doing OOP in js.

org.glassfish.jersey.servlet.ServletContainer ClassNotFoundException

I had the same problem with eclipse, the WA solution was to copy the libs to WEB-INF/lib

How to use: while not in

In your case, ('AND' and 'OR' and 'NOT') evaluates to "NOT", which may or may not be in your list...

while 'AND' not in MyList and 'OR' not in MyList and 'NOT' not in MyList:
    print 'No Boolean Operator'

Crop image in android

Can you use default android Crop functionality?

Here is my code

private void performCrop(Uri picUri) {
    try {
        Intent cropIntent = new Intent("");
        // indicate image type and Uri
        cropIntent.setDataAndType(picUri, "image/*");
        // set crop properties here
        cropIntent.putExtra("crop", true);
        // indicate aspect of desired crop
        cropIntent.putExtra("aspectX", 1);
        cropIntent.putExtra("aspectY", 1);
        // indicate output X and Y
        cropIntent.putExtra("outputX", 128);
        cropIntent.putExtra("outputY", 128);
        // retrieve data on return
        cropIntent.putExtra("return-data", true);
        // start the activity - we handle returning in onActivityResult
        startActivityForResult(cropIntent, PIC_CROP);
    // respond to users whose devices do not support the crop action
    catch (ActivityNotFoundException anfe) {
        // display an error message
        String errorMessage = "Whoops - your device doesn't support the crop action!";
        Toast toast = Toast.makeText(this, errorMessage, Toast.LENGTH_SHORT);;


final int PIC_CROP = 1;

at top.

In onActivity result method, writ following code:

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == PIC_CROP) {
        if (data != null) {
            // get the returned data
            Bundle extras = data.getExtras();
            // get the cropped bitmap
            Bitmap selectedBitmap = extras.getParcelable("data");


It is pretty easy for me to implement and also shows darken areas.

How to set height property for SPAN

Give it a display:inline-block in CSS - that should let it do what you want.
In terms of compatibility: IE6/7 will work with this, as quirks mode suggests:

IE 6/7 accepts the value only on elements with a natural display: inline.

How to get the IP address of the docker host from inside a docker container

If you want real IP address (not a bridge IP) on Windows and you have docker 18.03 (or more recent) do the following:

Run bash on container from host where image name is nginx (works on Alpine Linux distribution):

 docker run -it nginx /bin/ash

Then run inside container

/ # nslookup host.docker.internal

Name:      host.docker.internal
Address 1: is the host's IP - not the bridge IP like in spinus accepted answer.

I am using here host.docker.internal:

The host has a changing IP address (or none if you have no network access). From 18.03 onwards our recommendation is to connect to the special DNS name host.docker.internal, which resolves to the internal IP address used by the host. This is for development purpose and will not work in a production environment outside of Docker for Windows.

How to load a jar file at runtime

I was asked to build a java system that will have the ability to load new code while running

You might want to base your system on OSGi (or at least take a lot at it), which was made for exactly this situation.

Messing with classloaders is really tricky business, mostly because of how class visibility works, and you do not want to run into hard-to-debug problems later on. For example, Class.forName(), which is widely used in many libraries does not work too well on a fragmented classloader space.

How to reset Django admin password?

Another way to get the user name (and most of the information) is to access the database directly and read the info from the tables.

Creating a DateTime in a specific Time Zone in c#

You'll have to create a custom object for that. Your custom object will contain two values:

Not sure if there already is a CLR-provided data type that has that, but at least the TimeZone component is already available.

How to close form

There are different methods to open or close winform. Form.Close() is one method in closing a winform.

When 'Form.Close()' execute , all resources created in that form are destroyed. Resources means control and all its child controls (labels , buttons) , forms etc.

Some other methods to close winform

  1. Form.Hide()
  2. Application.Exit()

Some methods to Open/Start a form

  1. Form.Show()
  2. Form.ShowDialog()
  3. Form.TopMost()

All of them act differently , Explore them !

How do I multiply each element in a list by a number?

You can just use a list comprehension:

my_list = [1, 2, 3, 4, 5]
my_new_list = [i * 5 for i in my_list]

>>> print(my_new_list)
[5, 10, 15, 20, 25]

Note that a list comprehension is generally a more efficient way to do a for loop:

my_new_list = []
for i in my_list:
    my_new_list.append(i * 5)

>>> print(my_new_list)
[5, 10, 15, 20, 25]

As an alternative, here is a solution using the popular Pandas package:

import pandas as pd

s = pd.Series(my_list)

>>> s * 5
0     5
1    10
2    15
3    20
4    25
dtype: int64

Or, if you just want the list:

>>> (s * 5).tolist()
[5, 10, 15, 20, 25]

Identify duplicate values in a list in Python

I tried below code to find duplicate values from list

1) create a set of duplicate list

2) Iterated through set by looking in duplicate list.

glist=[1, 2, 3, "one", 5, 6, 1, "one"]
for c in x:


[1, 'one']

Now get the all index for duplicate element

glist=[1, 2, 3, "one", 5, 6, 1, "one"]
for c in x:
        indices = [i for i, x in enumerate(glist) if x == c]


[(1, [0, 6]), ('one', [3, 7])]

Hope this helps someone

Apache redirect to another port

I solved this issue with the following code:

LoadModule proxy_module modules/
LoadModule proxy_http_module modules/
<VirtualHost *:80>
ProxyPreserveHost On
ProxyRequests Off
ProxyPass / http://localhost:8080/
ProxyPassReverse / http://localhost:8080/

I also used:

a2enmod proxy_http

jQuery multiple conditions within if statement

A more general approach:

if ( ($("body").hasClass("homepage") || $("body").hasClass("contact")) && (theLanguage == 'en-gb') )   {

       // Do something


Open multiple Eclipse workspaces on the Mac

You can run multiple instances of Eclipse by creating a pseudonym for Eclipse application in it's folder and using it for running new Eclipse instance

How to sort an associative array by its values in Javascript?

Javascript doesn't have "associative arrays" the way you're thinking of them. Instead, you simply have the ability to set object properties using array-like syntax (as in your example), plus the ability to iterate over an object's properties.

The upshot of this is that there is no guarantee as to the order in which you iterate over the properties, so there is nothing like a sort for them. Instead, you'll need to convert your object properties into a "true" array (which does guarantee order). Here's a code snippet for converting an object into an array of two-tuples (two-element arrays), sorting it as you describe, then iterating over it:

var tuples = [];

for (var key in obj) tuples.push([key, obj[key]]);

tuples.sort(function(a, b) {
    a = a[1];
    b = b[1];

    return a < b ? -1 : (a > b ? 1 : 0);

for (var i = 0; i < tuples.length; i++) {
    var key = tuples[i][0];
    var value = tuples[i][1];

    // do something with key and value

You may find it more natural to wrap this in a function which takes a callback:

function bySortedValue(obj, callback, context) {_x000D_
  var tuples = [];_x000D_
  for (var key in obj) tuples.push([key, obj[key]]);_x000D_
  tuples.sort(function(a, b) {_x000D_
    return a[1] < b[1] ? 1 : a[1] > b[1] ? -1 : 0_x000D_
  var length = tuples.length;_x000D_
  while (length--), tuples[length][0], tuples[length][1]);_x000D_
  foo: 1,_x000D_
  bar: 7,_x000D_
  baz: 3_x000D_
}, function(key, value) {_x000D_
  document.getElementById('res').innerHTML += `${key}: ${value}<br>`_x000D_
<p id='res'>Result:<br/><br/><p>

How to reverse a singly linked list using only two pointers?

Following is one implementation using 2 pointers (head and r)

ListNode * reverse(ListNode* head) {

    ListNode *r = NULL;

    if(head) {
        r = head->next;
        head->next = NULL;

    while(r) {
        head = reinterpret_cast<ListNode*>(size_t(head) ^ size_t(r->next));
        r->next = reinterpret_cast<ListNode*>(size_t(r->next) ^ size_t(head));
        head = reinterpret_cast<ListNode*>(size_t(head) ^ size_t(r->next));

        head = reinterpret_cast<ListNode*>(size_t(head) ^ size_t(r));
        r = reinterpret_cast<ListNode*>(size_t(r) ^ size_t(head));
        head = reinterpret_cast<ListNode*>(size_t(head) ^ size_t(r));
    return head;

How do I write a SQL query for a specific date range and date time using SQL Server 2008?

How about this?

SELECT Value, ReadTime, ReadDate
WHERE CAST(ReadDate AS DATETIME) + ReadTime BETWEEN '2010-09-16 17:00:00' AND '2010-09-21 09:00:00'

EDIT: output according to OP's wishes ;-)

MySQL - Get row number on select

SELECT @rn:=@rn+1 AS rank, itemID, ordercount
  SELECT itemID, COUNT(*) AS ordercount
  FROM orders
  ORDER BY ordercount DESC
) t1, (SELECT @rn:=0) t2;

How to control the width and height of the default Alert Dialog in Android?

I think tir38's answer is the cleanest solution. Have in mind that if you are using and holo themes your style should look like this

<style name="WrapEverythingDialog" parent=[holo theme ex. android:Theme.Holo.Dialog]>
    <item name="windowMinWidthMajor">0dp</item>
    <item name="windowMinWidthMinor">0dp</item>

And if using or with AppCompat theme your style should look like this

<style name="WrapEverythingDialog" parent=[Appcompat theme ex. Theme.AppCompat.Light.Dialog.Alert]>
    <item name="android:windowMinWidthMajor">0dp</item>
    <item name="android:windowMinWidthMinor">0dp</item>

How to specify the current directory as path in VBA?

I thought I had misunderstood but I was right. In this scenario, it will be ActiveWorkbook.Path

But the main issue was not here. The problem was with these 2 lines of code

strFile = Dir(strPath & "*.csv")

Which should have written as

strFile = Dir(strPath & "\*.csv")


With .QueryTables.Add(Connection:="TEXT;" & strPath & strFile, _

Which should have written as

With .QueryTables.Add(Connection:="TEXT;" & strPath & "\" & strFile, _

Which MIME type to use for a binary file that's specific to my program?

I'd recommend application/octet-stream as RFC2046 says "The "octet-stream" subtype is used to indicate that a body contains arbitrary binary data" and "The recommended action for an implementation that receives an "application/octet-stream" entity is to simply offer to put the data in a file[...]".

I think that way you will get better handling from arbitrary programs, that might barf when encountering your unknown mime type.

How to uninstall mini conda? python

your have to comment that line in ~/.bashrc:

#export PATH=/home/jolth/miniconda3/bin:$PATH

and run:

source ~/.bashrc

How to convert Json array to list of objects in c#

This is possible too:

using System.Web.Helpers;
var listOfObjectsResult = Json.Decode<List<DataType>>(JsonData);

Inner text shadow with CSS

Seems everyone's got an answer to this one. I like the solution from @Web_Designer. But it doesn't need to be as complex as that and you can still get the blurry inner shadow you're looking for.

.depth {
    display: block;
    padding: 50px;
    color: black;
    font: bold 7em Arial, sans-serif;
    position: relative;

.depth:before {
    content: attr(title);
    color: transparent;
    position: absolute;
    text-shadow: 2px 2px 4px rgba(255,255,255,0.3);

ReferenceError: fetch is not defined

If it has to be accessible with a global scope

global.fetch = require("node-fetch");

This is a quick dirty fix, please try to eliminate this usage in production code.

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '...' is therefore not allowed access

Pleaes find the Function used in XMLHTTPREQUEST in Javascript for setting up the request headers.


xmlHttp.setRequestHeader("Access-Control-Allow-Origin", "");


Get the date (a day before current time) in Bash

if you have GNU date and i understood you correctly

$ date +%Y:%m:%d -d "yesterday"


$ date +%Y:%m:%d -d "1 day ago"

How does one create an InputStream from a String?

InputStream in = new ByteArrayInputStream(yourstring.getBytes());

How can I get the current network interface throughput statistics on Linux/UNIX?

Got sar? Likely yes if youre using RHEL/CentOS.

No need for priv, dorky binaries, hacky scripts, libpcap, etc. Win.

$ sar -n DEV 1 3
Linux 2.6.18-194.el5 (localhost.localdomain)    10/27/2010

02:40:56 PM     IFACE   rxpck/s   txpck/s   rxbyt/s   txbyt/s   rxcmp/s   txcmp/s  rxmcst/s
02:40:57 PM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
02:40:57 PM      eth0  10700.00   1705.05 15860765.66 124250.51      0.00      0.00      0.00
02:40:57 PM      eth1      0.00      0.00      0.00      0.00      0.00      0.00      0.00

02:40:57 PM     IFACE   rxpck/s   txpck/s   rxbyt/s   txbyt/s   rxcmp/s   txcmp/s  rxmcst/s
02:40:58 PM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
02:40:58 PM      eth0   8051.00   1438.00 11849206.00 105356.00      0.00      0.00      0.00
02:40:58 PM      eth1      0.00      0.00      0.00      0.00      0.00      0.00      0.00

02:40:58 PM     IFACE   rxpck/s   txpck/s   rxbyt/s   txbyt/s   rxcmp/s   txcmp/s  rxmcst/s
02:40:59 PM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
02:40:59 PM      eth0   6093.00   1135.00 8970988.00  82942.00      0.00      0.00      0.00
02:40:59 PM      eth1      0.00      0.00      0.00      0.00      0.00      0.00      0.00

Average:        IFACE   rxpck/s   txpck/s   rxbyt/s   txbyt/s   rxcmp/s   txcmp/s  rxmcst/s
Average:           lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00
Average:         eth0   8273.24   1425.08 12214833.44 104115.72      0.00      0.00      0.00
Average:         eth1      0.00      0.00      0.00      0.00      0.00      0.00      0.00

Animate change of view background color on Android

Depending on how your view gets its background color and how you get your target color there are several different ways to do this.

The first two uses the Android Property Animation framework.

Use a Object Animator if:

  • Your view have its background color defined as a argb value in a xml file.
  • Your view have previously had its color set by view.setBackgroundColor()
  • Your view have its background color defined in a drawable that DOES NOT defines any extra properties like stroke or corner radiuses.
  • Your view have its background color defined in a drawable and you want to remove any extra properties like stroke or corner radiuses, keep in mind that the removal of the extra properties will not animated.

The object animator works by calling view.setBackgroundColor which replaces the defined drawable unless is it an instance of a ColorDrawable, which it rarely is. This means that any extra background properties from a drawable like stroke or corners will be removed.

Use a Value Animator if:

  • Your view have its background color defined in a drawable that also sets properties like the stroke or corner radiuses AND you want to change it to a new color that is decided while running.

Use a Transition drawable if:

  • Your view should switch between two drawable that have been defined before deployment.

I have had some performance issues with Transition drawables that runs while I am opening a DrawerLayout that I haven't been able to solve, so if you encounter any unexpected stuttering you might have run into the same bug as I have.

You will have to modify the Value Animator example if you want to use a StateLists drawable or a LayerLists drawable, otherwise it will crash on the final GradientDrawable background = (GradientDrawable) view.getBackground(); line.

Object Animator:

View definition:


Create and use a ObjectAnimator like this.

final ObjectAnimator backgroundColorAnimator = ObjectAnimator.ofObject(view,
                                                                       new ArgbEvaluator(),

You can also load the animation definition from a xml using a AnimatorInflater like XMight does in Android objectAnimator animate backgroundColor of Layout

Value Animator:

View definition:


Drawable definition:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="">
    <solid android:color="#FFFFFF"/>
    <corners android:radius="3dp"/>


Create and use a ValueAnimator like this:

final ValueAnimator valueAnimator = ValueAnimator.ofObject(new ArgbEvaluator(),

final GradientDrawable background = (GradientDrawable) view.getBackground();
currentAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

    public void onAnimationUpdate(final ValueAnimator animator) {
        background.setColor((Integer) animator.getAnimatedValue());


Transition drawable:

View definition:


Drawable definition:

<?xml version="1.0" encoding="utf-8"?>
<transition xmlns:android="">
            <solid android:color="#FFFFFF"/>
            <corners android:radius="3dp"/>

            <solid android:color="#78c5f9"/>
            <corners android:radius="3dp"/>

Use the TransitionDrawable like this:

final TransitionDrawable background = (TransitionDrawable) view.getBackground();

You can reverse the animations by calling .reverse() on the animation instance.

There are some other ways to do animations but these three is probably the most common. I generally use a ValueAnimator.

How to read from a text file using VBScript?

Dim obj : Set obj = CreateObject("Scripting.FileSystemObject")
Dim outFile : Set outFile = obj.CreateTextFile("in.txt")
Dim inFile: Set inFile = obj.OpenTextFile("out.txt")

' Read file
Dim strRetVal : strRetVal = inFile.ReadAll

' Write file
outFile.write (strRetVal)

How to use JavaScript with Selenium WebDriver Java

I didn't see how to add parameters to the method call, it took me a while to find it, so I add it here. How to pass parameters in (to the javascript function), use "arguments[0]" as the parameter place and then set the parameter as input parameter in the executeScript function.

    driver.executeScript("function(arguments[0]);","parameter to send in");

What's a quick way to comment/uncomment lines in Vim?

I use comments.vim from Jasmeet Singh Anand (found on,

It works with C, C++, Java, PHP[2345], proc, CSS, HTML, htm, XML, XHTML, vim, vimrc, SQL, sh, ksh, csh, Perl, tex, fortran, ml, caml, ocaml, vhdl, haskel, and normal files

It comments and un-comments lines in different source files in both normal and visual mode


  • CtrlC to comment a single line
  • CtrlX to un-comment a single line
  • ShiftV and select multiple lines, then CtrlC to comment the selected multiple lines
  • ShiftV and select multiple lines, then CtrlX to un-comment the selected multiple lines

How to present a modal atop the current view in Swift

The problem with setting the modalPresentationStyle from code was that you should have set it in the init() method of the presented view controller, not the parent view controller.

From UIKit docs: "Defines the transition style that will be used for this view controller when it is presented modally. Set this property on the view controller to be presented, not the presenter. Defaults to UIModalTransitionStyleCoverVertical."

The viewDidLoad method will only be called after you already presented the view controller.

The second problem was that you should use UIModalPresentationStyle.overCurrentContext.

Get the difference between dates in terms of weeks, months, quarters, and years

I just wrote this for another question, then stumbled here.


#' Calculate age
#' By default, calculates the typical "age in years", with a
#' \code{floor} applied so that you are, e.g., 5 years old from
#' 5th birthday through the day before your 6th birthday. Set
#' \code{floor = FALSE} to return decimal ages, and change \code{units}
#' for units other than years.
#' @param dob date-of-birth, the day to start calculating age.
#' @param the date on which age is to be calculated.
#' @param units unit to measure age in. Defaults to \code{"years"}. Passed to \link{\code{duration}}.
#' @param floor boolean for whether or not to floor the result. Defaults to \code{TRUE}.
#' @return Age in \code{units}. Will be an integer if \code{floor = TRUE}.
#' @examples
#' my.dob <- as.Date('1983-10-20')
#' age(my.dob)
#' age(my.dob, units = "minutes")
#' age(my.dob, floor = FALSE)
age <- function(dob, = today(), units = "years", floor = TRUE) {
    calc.age = interval(dob, / duration(num = 1, units = units)
    if (floor) return(as.integer(floor(calc.age)))

Usage examples:

my.dob <- as.Date('1983-10-20')

# [1] 31

age(my.dob, floor = FALSE)
# [1] 31.15616

age(my.dob, units = "minutes")
# [1] 16375680

age(seq(my.dob, length.out = 6, by = "years"))
# [1] 31 30 29 28 27 26

import an array in python

(I know the question is old, but I think this might be good as a reference for people with similar questions)

If you want to load data from an ASCII/text file (which has the benefit or being more or less human-readable and easy to parse in other software), numpy.loadtxt is probably what you want:

If you just want to quickly save and load numpy arrays/matrices to and from a file, take a look at and numpy.load:

SQL Server FOR EACH Loop

Here is an option with a table variable:

SET @I = 1
SET @StartDate = '20100101'

WHILE @I <= 5
    INSERT INTO @MyVar(Val)

    SET @StartDate = DATEADD(DAY,1,@StartDate)
    SET @I = @I + 1

You can do the same with a temp table:

SET @I = 1
SET @StartDate = '20100101'

WHILE @I <= 5
    INSERT INTO #MyVar(Val)

    SET @StartDate = DATEADD(DAY,1,@StartDate)
    SET @I = @I + 1

You should tell us what is your main goal, as was said by @JohnFx, this could probably be done another (more efficient) way.

Regular Expression to reformat a US phone number in Javascript

var x = '301.474.4062';_x000D_
x = x.replace(/\D+/g, '')_x000D_
     .replace(/(\d{3})(\d{3})(\d{4})/, '($1) $2-$3');_x000D_

How to launch another aspx web page upon button click?

Use an html button and javascript? in javascript, window.location is used to change the url location of the current window, while will open a new one

<input type="button" onclick="'newPage.aspx', 'newPage');" />

Edit: Ah, just found this: If the ID of your form tag is form1, set this attribute in your asp button

OnClientClick=" ='_blank';"

Efficient way to Handle ResultSet in Java

I just cleaned up RHT's answer to eliminate some warnings and thought I would share. Eclipse did most of the work:

public List<HashMap<String,Object>> convertResultSetToList(ResultSet rs) throws SQLException {
    ResultSetMetaData md = rs.getMetaData();
    int columns = md.getColumnCount();
    List<HashMap<String,Object>> list = new ArrayList<HashMap<String,Object>>();

    while ( {
        HashMap<String,Object> row = new HashMap<String, Object>(columns);
        for(int i=1; i<=columns; ++i) {

    return list;

Hiding the scroll bar on an HTML page

My answer will scroll even when overflow:hidden;, using jQuery:

For example, scroll horizontally with the mouse wheel:

<script src=""></script>
<script type='text/javascript' src='/js/jquery.mousewheel.min.js'></script>
<script type="text/javascript">
    $(function() {

       $("YourSelector").mousewheel(function(event, delta) {

          this.scrollLeft -= (delta * 30);

Is it possible to get multiple values from a subquery?

In Oracle query

select a.x
            ,(select b.y || ',' || b.z
                from   b
                where  b.v = a.v
                and    rownum = 1) as multple_columns
from   a

can be transformed to:

select a.x, b1.y, b1.z
from   a, b b1
where  b1.rowid = (
       select b.rowid
       from   b
       where  b.v = a.v
       and    rownum = 1

Is useful when we want to prevent duplication for table A. Similarly, we can increase the number of tables:

.... where (b1.rowid,c1.rowid) = (select b.rowid,c.rowid ....

How do you make a LinearLayout scrollable?

You need to place ScrollView as the first child of Layout file and now put your linearlayout inside it. Now, android will decide on the basis of content and device size available whether to show a scrollable or not.

Make sure linearlayout has no sibling because ScrollView can not have more than one child.

Add IIS 7 AppPool Identities as SQL Server Logons

The "IIS APPPOOL\AppPoolName" will work, but as mentioned previously, it does not appear to be a valid AD name so when you search for it in the "Select User or Group" dialog box, it won't show up (actually, it will find it, but it will think its an actual system account, and it will try to treat it as such...which won't work, and will give you the error message about it not being found).

How I've gotten it to work is:

  1. In SQL Server Management Studio, look for the Security folder (the security folder at the same level as the Databases, Server Objects, etc. folders...not the security folder within each individual database)
  2. Right click logins and select "New Login"
  3. In the Login name field, type IIS APPPOOL\YourAppPoolName - do not click search
  4. Fill whatever other values you like (i.e., authentication type, default database, etc.)
  5. Click OK

As long as the AppPool name actually exists, the login should now be created.

Is this how you define a function in jQuery?


You define the functions exactly the same way you would in regular javascript.

//document ready

var myBlah = function(blah){

Also: There is no need for the $

The remote certificate is invalid according to the validation procedure

I had the same problem while I was testing a project and it turned that running Fiddler was the cause for this error..!!

If you are using Fiddler to intercept the http request, shut it down ...

This is one of the many causes for such error.

To fix Fiddler you may need to Reset Fiddler Https Certificates.

Get min and max value in PHP Array

$Location_Category_array = array(5,50,7,6,1,7,7,30,50,50,50,40,50,9,9,11,2,2,2,2,2,11,21,21,1,12,1,5);

$count=array_count_values($Location_Category_array);//Counts the values in the array, returns associatve array
        $maxsize = 0;
        $maxvalue = 0;
        foreach($count as $a=>$y){
            echo "<br/>".$a."=".$y;
                $maxvalue = $y;
                    $maxsize = $a;

    echo "<br/>max = ".$maxsize;

How do I put all required JAR files in a library folder inside the final JAR file with Maven?

Here´s how I do it:


And then I just run:

mvn assembly:assembly

How to use fetch in typescript

If you take a look at @types/node-fetch you will see the body definition

export class Body {
    bodyUsed: boolean;
    body: NodeJS.ReadableStream;
    json(): Promise<any>;
    json<T>(): Promise<T>;
    text(): Promise<string>;
    buffer(): Promise<Buffer>;

That means that you could use generics in order to achieve what you want. I didn't test this code, but it would looks something like this:

import { Actor } from './models/actor';

      .then(res => res.json<Actor>())
      .then(res => {
          let b:Actor = res;

what does mysql_real_escape_string() really do?

The function adds an escape character, the backslash, \, before certain potentially dangerous characters in a string passed in to the function. The characters escaped are

\x00, \n, \r, \, ', " and \x1a.

This can help prevent SQL injection attacks which are often performed by using the ' character to append malicious code to an SQL query.

How to select data from 30 days?

For those who could not get DATEADD to work, try this instead: ( NOW( ) - INTERVAL 1 MONTH )

How do I add a simple jQuery script to WordPress?

Beside putting the script in through functions you can "just" include a link ( a link rel tag that is) in the header, the footer, in any template, where ever.

No. You should never just add a link to an external script like this in WordPress. Enqueuing them through the functions.php file ensures that scripts are loaded in the correct order.

Failure to enqueue them may result in your script not working, although it is written correctly.

Convert NVARCHAR to DATETIME in SQL Server 2008

What you exactly wan't to do ?. To change Datatype of column you can simple use alter command as

ALTER TABLE table_name ALTER COLUMN LoginDate DateTime;

But remember there should valid Date only in this column however data-type is nvarchar.

If you wan't to convert data type while fetching data then you can use CONVERT function as,



SELECT CONVERT(DateTime, loginDate, 6)

This will return 29 AUG 13. For details about CONVERT function you can visit ,

Remember, Always use DataTime data type for DateTime column.

Thank You

How do I use Apache tomcat 7 built in Host Manager gui?

Tomcat 8:

The following worked for me with tomcat 8.

Add these lines to apache-tomcat-8.0.9/conf/tomcat-users.xml

For Manager:

<role rolename="manager-gui"/>
<user username="admin" password="pass" roles="manager-gui"/>

For Host Manager:

<role rolename="admin-gui"/>
<user username="admin" password="pass" roles="admin-gui"/>

Download File to server from URL

Use a simple method in php copy()

copy($source_url, $local_path_with_file_name);

Note: if the destination file already exists, it will be overwritten

PHP copy() Function

Note: You need to set permission 777 for the destination folder. Use this method when you are downloading to your local machine.

Special Note: 777 is a permission in Unix based system with full read/write/execute permission to owner, group and everyone. In general we give this permission to assets which are not much needed to be hidden from public on a web server. Example: images folder.

Shrink to fit content in flexbox, or flex-basis: content workaround?

It turns out that it was shrinking and growing correctly, providing the desired behaviour all along; except that in all current browsers flexbox wasn't accounting for the vertical scrollbar! Which is why the content appears to be getting cut off.

You can see here, which is the original code I was using before I added the fixed widths, that it looks like the column isn't growing to accomodate the text:

However if you make the content in that column wider, you'll see that it always cuts it off by the same amount, which is the width of the scrollbar.

So the fix is very, very simple - add enough right padding to account for the scrollbar:

  main > section {_x000D_
    overflow-y: auto;_x000D_
    padding-right: 2em;_x000D_

It was when I was trying some things suggested by Michael_B (specifically adding a padding buffer) that I discovered this, thanks so much!

Edit: I see that he also posted a fiddle which does the same thing - again, thanks so much for all your help

String to Binary in C#

Here's an extension function:

        public static string ToBinary(this string data, bool formatBits = false)
            char[] buffer = new char[(((data.Length * 8) + (formatBits ? (data.Length - 1) : 0)))];
            int index = 0;
            for (int i = 0; i < data.Length; i++)
                string binary = Convert.ToString(data[i], 2).PadLeft(8, '0');
                for (int j = 0; j < 8; j++)
                    buffer[index] = binary[j];
                if (formatBits && i < (data.Length - 1))
                    buffer[index] = ' ';
            return new string(buffer);

You can use it like:


and if you add 'true' as a parameter, it will automatically separate each binary sequence.

Difference between "while" loop and "do while" loop


If wdlen (assuming it's a stack variable) is not initialized or assigned a value before the while loop is entered, it will contain whatever was in that space in memory before (i.e. garbage). So if the garbage value is < 2, the loop executes, otherwise it doesn't.


will execute once and then checks on condition to run loop again, and this time it might succeed if by chance wdlen which is uninitialized is found to be less than 2.

jQuery get the id/value of <li> element after click function

$("#myid li").click(function() {
    alert(; // id of clicked li by directly accessing DOMElement property
    alert($(this).attr('id')); // jQuery's .attr() method, same but more verbose
    alert($(this).html()); // gets innerHTML of clicked li
    alert($(this).text()); // gets text contents of clicked li

If you are talking about replacing the ID with something:

$("#myid li").click(function() { = 'newId';

    // longer method using .attr()
    $(this).attr('id', 'newId');

Demo here. And to be fair, you should have first tried reading the documentation:

What are the default access modifiers in C#?

Class is Internal by default.

  • Class members are private by default.

Interface is Internal by default.

  • Interface members are public by default. (Interfaces won't allow us to specify any kind of accessibility to it's members.)

    Note: If you try to specify any access specifier to interface's members then, it shows compile error.

Struct is Internal by default.

  • Struct members are private by default.

Align div right in Bootstrap 3

Add offset8 to your class, for example:

<div class="offset8">aligns to the right</div>

Writing your own square root function

Let me point out an extremely interesting method of calculating an inverse square root 1/sqrt(x) which is a legend in the world of game design because it is mind-boggingly fast. Or wait, read the following post:

PS: I know you just want the square root but the elegance of quake overcame all resistance on my part :)

By the way, the above mentioned article also talks about the boring Newton-Raphson approximation somewhere.

Where to get "UTF-8" string literal in Java?

In Java 1.7+, java.nio.charset.StandardCharsets defines constants for Charset including UTF_8.

import java.nio.charset.StandardCharsets;


For Android: minSdk 19

Is there a kind of Firebug or JavaScript console debug for Android?

Chrome has a very nice feature called 'USB Web debugging' which allows to see the mobile device's debug console on your PC when connected via USB.

See here for more details.

EDIT: Seems that the ADB is not supported on Windows 8, but this link seems to provide a solution:

How to auto adjust table td width from the content

Remove all widths set using CSS and set white-space to nowrap like so:

.content-loader tr td {
    white-space: nowrap;

I would also remove the fixed width from the container (or add overflow-x: scroll to the container) if you want the fields to display in their entirety without it looking odd...

See more here:

In ASP.NET MVC: All possible ways to call Controller Action Method from a Razor View

Method 1 : Using jQuery Ajax Get call (partial page update).

Suitable for when you need to retrieve jSon data from database.

Controller's Action Method

public ActionResult Foo(string id)
    var person = Something.GetPersonByID(id);
    return Json(person, JsonRequestBehavior.AllowGet);

Jquery GET

function getPerson(id) {
        url: '@Url.Action("Foo", "SomeController")',
        type: 'GET',
        dataType: 'json',
        // we set cache: false because GET requests are often cached by browsers
        // IE is particularly aggressive in that respect
        cache: false,
        data: { id: id },
        success: function(person) {

Person class

public class Person
    public string FirstName { get; set; }
    public string LastName { get; set; }

Method 2 : Using jQuery Ajax Post call (partial page update).

Suitable for when you need to do partial page post data into database.

Post method is also same like above just replace [HttpPost] on Action method and type as post for jquery method.

For more information check Posting JSON Data to MVC Controllers Here

Method 3 : As a Form post scenario (full page update).

Suitable for when you need to save or update data into database.


@using (Html.BeginForm("SaveData","ControllerName", FormMethod.Post))
    @Html.TextBoxFor(model => m.Text)
    <input type="submit" value="Save" />

Action Method

public ActionResult SaveData(FormCollection form)
        // Get movie to update
        return View();

Method 4 : As a Form Get scenario (full page update).

Suitable for when you need to Get data from database

Get method also same like above just replace [HttpGet] on Action method and FormMethod.Get for View's form method.

I hope this will help to you.

What is the difference between method overloading and overriding?

Method overloading deals with the notion of having two or more methods in the same class with the same name but different arguments.

void foo(int a)
void foo(int a, float b)

Method overriding means having two methods with the same arguments, but different implementations. One of them would exist in the parent class, while another will be in the derived, or child class. The @Override annotation, while not required, can be helpful to enforce proper overriding of a method at compile time.

class Parent {
    void foo(double d) {
        // do something

class Child extends Parent {

    void foo(double d){
        // this method is overridden.  

How to use registerReceiver method?

Broadcast receivers receive events of a certain type. I don't think you can invoke them by class name.

First, your IntentFilter must contain an event.

static final String SOME_ACTION = "com.yourcompany.yourapp.SOME_ACTION";
IntentFilter intentFilter = new IntentFilter(SOME_ACTION);

Second, when you send a broadcast, use this same action:

Intent i = new Intent(SOME_ACTION);

Third, do you really need MyIntentService to be inline? Static? [EDIT] I discovered that MyIntentSerivce MUST be static if it is inline.

Fourth, is your service declared in the AndroidManifest.xml?

What's the Use of '\r' escape sequence?

The '\r' stands for "Carriage Return" - it's a holdover from the days of typewriters and really old printers. The best example is in Windows and other DOSsy OSes, where a newline is given as "\r\n". These are the instructions sent to an old printer to start a new line: first move the print head back to the beginning, then go down one.

Different OSes will use other newline sequences. Linux and OSX just use '\n'. Older Mac OSes just use '\r'. Wikipedia has a more complete list, but those are the important ones.

Hope this helps!

PS: As for why you get that weird output... Perhaps the console is moving the "cursor" back to the beginning of the line, and then overwriting the first bit with spaces or summat.

How do I install Keras and Theano in Anaconda Python on Windows?

I use macOS and used to have the same problem.
Running the following command in the terminal saved me:

conda install -c conda-forge keras tensorflow

Hope it helps.

How to ignore whitespace in a regular expression subject string?

You can stick optional whitespace characters \s* in between every other character in your regex. Although granted, it will get a bit lengthy.

/cats/ -> /c\s*a\s*t\s*s/

Python Inverse of a Matrix

It is a pity that the chosen matrix, repeated here again, is either singular or badly conditioned:

A = matrix( [[1,2,3],[11,12,13],[21,22,23]])

By definition, the inverse of A when multiplied by the matrix A itself must give a unit matrix. The A chosen in the much praised explanation does not do that. In fact just looking at the inverse gives a clue that the inversion did not work correctly. Look at the magnitude of the individual terms - they are very, very big compared with the terms of the original A matrix...

It is remarkable that the humans when picking an example of a matrix so often manage to pick a singular matrix!

I did have a problem with the solution, so looked into it further. On the ubuntu-kubuntu platform, the debian package numpy does not have the matrix and the linalg sub-packages, so in addition to import of numpy, scipy needs to be imported also.

If the diagonal terms of A are multiplied by a large enough factor, say 2, the matrix will most likely cease to be singular or near singular. So

A = matrix( [[2,2,3],[11,24,13],[21,22,46]])

becomes neither singular nor nearly singular and the example gives meaningful results... When dealing with floating numbers one must be watchful for the effects of inavoidable round off errors.

Thanks for your contribution,


how to convert binary string to decimal?

parseInt() with radix is a best solution (as was told by many):

But if you want to implement it without parseInt, here is an implementation:

  function bin2dec(num){
    return num.split('').reverse().reduce(function(x, y, i){
      return (y === '1') ? x + Math.pow(2, i) : x;
    }, 0);

java.lang.IllegalArgumentException: No converter found for return value of type

I faced the same problem but I was using Lombok and my UploadFileResponse pojo was a builder.

public ResponseEntity<UploadFileResponse> 

To solve I added @Getter annotation:

public class UploadFileResponse

JSLint says "missing radix parameter"

Prior to ECMAScript 5, parseInt() also autodetected octal literals, which caused problems because many developers assumed a leading 0 would be ignored.

So Instead of :

var num = parseInt("071");      // 57

Do this:

var num = parseInt("071", 10);  // 71

var num = parseInt("071", 8);

var num = parseFloat(someValue); 


Using GSON to parse a JSON array

Wrapper[] data = gson.fromJson(jElement, Wrapper[].class);

Why am I getting "Cannot Connect to Server - A network-related or instance-specific error"?

I moved from a work laptop on Windows 7 to a work laptop on Windows 10. I had been successfully using SSMS2016 on Windows 7.

The same issue applied using SSMS2012 or SSMS2016. My access to the 10 sql servers using windows authentication was still the same. I could test this from another server. However, 2 of the 10 servers would not connect from my laptop. Both were ms sql server 9 but I could connect to other sql server 9 databases.

The solution was to add a firewall rule (using Windows Firewall with Advanced Security).

Create an Incoming rule for each SSMS eg C:\Program Files (x86)\Microsoft SQL Server\130\Tools\Binn\ManagementStudio\Ssms.exe

I'm not a network expert so I've not included the details but hopefully it will point you in the right direction.

Error msg (pre firewall rule) "A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) (.Net SqlClient Data Provider)"

Node.js: Python not found exception due to node-sass and node-gyp

My answer might not apply to everyone. Node version: v10.16.0 NPM: 6.9.0

I was having a lot of trouble using node-sass and node-sass-middleware. They are interesting packages because they are widely used (millions of downloads weekly), but their githubs show a limited dependencies and coverage. I was updating an older platform I'd been working on.

What I ended up having to do was:

1) Manually Delete node_modules

2) Manually Delete package-lock.json

3) sudo npm install node-sass --unsafe-perm=true --allow-root

4) sudo npm install node-sass-middleware --unsafe-perm=true --allow-root

I had the following help, thanks!

Pre-built binaries not found for [email protected] and [email protected]

Error: EACCES: permission denied when trying to install ESLint using npm

How do I connect to a specific Wi-Fi network in Android programmatically?

Try this method. It's very easy:

public static boolean setSsidAndPassword(Context context, String ssid, String ssidPassword) {
    try {
        WifiManager wifiManager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
        Method getConfigMethod = wifiManager.getClass().getMethod("getWifiApConfiguration");
        WifiConfiguration wifiConfig = (WifiConfiguration) getConfigMethod.invoke(wifiManager);

        wifiConfig.SSID = ssid;
        wifiConfig.preSharedKey = ssidPassword;

        Method setConfigMethod = wifiManager.getClass().getMethod("setWifiApConfiguration", WifiConfiguration.class);
        setConfigMethod.invoke(wifiManager, wifiConfig);

        return true;
    } catch (Exception e) {
        return false;

How to access remote server with local phpMyAdmin client?

I would have added this as a comment, but my reputation is not yet high enough.

Under version, and I am guessing any other versions 4.5.x or newer. There is no need to modify the file at all. Instead go one more directory down conf.d.

Create a new file with the '.php' extension and add the lines. This is a better modularized approach and isolates each remote database server access information.

Regex to split a CSV

I had a similar need for splitting CSV values from SQL insert statements.

In my case, I could assume that strings were wrapped in single quotations and numbers were not.

csv.split(/,((?=')|(?=\d))/g).filter(function(x) { return x !== '';});

For some probably obvious reason, this regex produces some blank results. I could ignore those, since any empty values in my data were represented as ...,'',... and not ...,,....

How can I get a random number in Kotlin?

Using a top-level function, you can achieve exactly the same call syntax as in Ruby (as you wish):

fun rand(s: Int, e: Int) = Random.nextInt(s, e + 1)


rand(1, 3) // returns either 1, 2 or 3

PivotTable to show values, not sum of values

I fear this might turn out to BE the long way round but could depend on how big your data set is – presumably more than four months for example.

Assuming your data is in ColumnA:C and has column labels in Row 1, also that Month is formatted mmm(this last for ease of sorting):

  1. Sort the data by Name then Month
  2. Enter in D2 =IF(AND(A2=A1,C2=C1),D1+1,1) (One way to deal with what is the tricky issue of multiple entries for the same person for the same month).
  3. Create a pivot table from A1:D(last occupied row no.)
  4. Say insert in F1.
  5. Layout as in screenshot.

SO12803305 example

I’m hoping this would be adequate for your needs because pivot table should automatically update (provided range is appropriate) in response to additional data with refresh. If not (you hard taskmaster), continue but beware that the following steps would need to be repeated each time the source data changes.

  1. Copy pivot table and Paste Special/Values to, say, L1.
  2. Delete top row of copied range with shift cells up.
  3. Insert new cell at L1 and shift down.
  4. Key 'Name' into L1.
  5. Filter copied range and for ColumnL, select Row Labels and numeric values.
  6. Delete contents of L2:L(last selected cell)
  7. Delete blank rows in copied range with shift cells up (may best via adding a column that counts all 12 months). Hopefully result should be as highlighted in yellow.

Happy to explain further/try again (I've not really tested this) if does not suit.

EDIT (To avoid second block of steps above and facilitate updating for source data changes)

.0. Before first step 2. add a blank row at the very top and move A2:D2 up.
.2. Adjust cell references accordingly (in D3 =IF(AND(A3=A2,C3=C2),D2+1,1).
.3. Create pivot table from A:D

.6. Overwrite Row Labels with Name.
.7. PivotTable Tools, Design, Report Layout, Show in Tabular Form and sort rows and columns A>Z.
.8. Hide Row1, ColumnG and rows and columns that show (blank).

additional example

Steps .0. and .2. in the edit are not required if the pivot table is in a different sheet from the source data (recommended).

Step .3. in the edit is a change to simplify the consequences of expanding the source data set. However introduces (blank) into pivot table that if to be hidden may need adjustment on refresh. So may be better to adjust source data range each time that changes instead: PivotTable Tools, Options, Change Data Source, Change Data Source, Select a table or range). In which case copy rather than move in .0.

Finding and removing non ascii characters from an Oracle Varchar2

Try the following:

-- To detect
select 1 from dual
where regexp_like(trim('xx test text æ¸¬è© ¦ “xmx” number²'),'['||chr(128)||'-'||chr(255)||']','in')

-- To strip out
select regexp_replace(trim('xx test text æ¸¬è© ¦ “xmxmx” number²'),'['||chr(128)||'-'||chr(255)||']','',1,0,'in')
from dual

Specified cast is not valid.. how to resolve this

Use Convert.ToDouble(value) rather than (double)value. It takes an object and supports all of the types you asked for! :)

Also, your method is always returning a string in the code above; I'd recommend having the method indicate so, and give it a more obvious name (public string FormatLargeNumber(object value))

Javascript receipt printing using POS Printer


Links below about the posts written by David Kelley are broken.

There are cached versions of the repository, just add cache: before the URL in the Chrome Browser and hit enter.

This solution is only for Google Chrome and Chromium-based browsers.


(*)The links are broken. Fortunately I found this repository that contains the source of the post in the following markdown files: A | B

This link* explains how to make a Javascript Interface for ESC/POS printers using Chrome/Chromium USB API (1)(2). This link* explains how to Connect to USB devices using the chrome.usb.* API.

Batch File; List files in directory, only filenames?

1.Open notepad

2.Create new file

3.type bellow line

dir /b > fileslist.txt

4.Save "list.bat"

Thats it. now you can copy & paste this "list.bat" file any of your folder location and double click it, it will create a "fileslist.txt" along with that directory folder and file name list.

Sample Output: enter image description here

Note: If you want create file name list along with sub folder, then you can create batch file with bellow code.

dir /b /s > fileslist.txt

Why does JS code "var a = document.querySelector('a[data-a=1]');" cause error?

From the selectors specification:

Attribute values must be CSS identifiers or strings.

Identifiers cannot start with a number. Strings must be quoted.

1 is therefore neither a valid identifier nor a string.

Use "1" (which is a string) instead.

var a = document.querySelector('a[data-a="1"]');

How do I get a PHP class constructor to call its parent's parent's constructor?


class grand_pa
    public function __construct()
        echo "Hey I am Grand Pa <br>";

class pa_pa extends grand_pa
    // no need for construct here unless you want to do something specifically within this class as init stuff
    // the construct for this class will be inherited from the parent.

class kiddo extends pa_pa
    public function __construct()
        echo "Hey I am a child <br>";

new kiddo();

Of course this expects you do not need to do anything within the construct of the pa_pa. Running this will output :

Hey I am Grand Pa Hey I am a child

Vertical align middle with Bootstrap responsive grid

Add !important rule to display: table of your .v-center class.

.v-center {
    display:table !important;
    border:2px solid gray;

Your display property is being overridden by bootstrap to display: block.


repaint() in Java

Simply write :


That will do .


What is the difference between dict.items() and dict.iteritems() in Python2?

dict.iteritems is gone in Python3.x So use iter(dict.items()) to get the same output and memory alocation

How to set a default row for a query that returns no rows?

This snippet uses Common Table Expressions to reduce redundant code and to improve readability. It is a variation of John Baughman's answer.

The syntax is for SQL Server.

WITH products AS (
            SELECT prod_name,
              FROM Products_Table
             WHERE prod_name LIKE '%foo%'
     defaults AS (
            SELECT '-' AS prod_name,
                   0   AS price

SELECT * FROM products
SELECT * FROM defaults

Logarithmic returns in pandas dataframe

Log returns are simply the natural log of 1 plus the arithmetic return. So how about this?

df['pct_change'] = df.price.pct_change()
df['log_return'] = np.log(1 + df.pct_change)

Even more concise, utilizing Ximix's suggestion:

df['log_return'] = np.log1p(df.price.pct_change())

Java - Convert String to valid URI object

Or perhaps you could use this class:

Which is present in Android since API level 1.

Annoyingly however, it treats spaces specially (replacing them with + instead of %20). To get round this we simply use this fragment:

URLEncoder.encode(value, "UTF-8").replace("+", "%20");

How to disable textbox from editing?

You can set the ReadOnly property to true.

Quoth the link:

When this property is set to true, the contents of the control cannot be changed by the user at runtime. With this property set to true, you can still set the value of the Text property in code. You can use this feature instead of disabling the control with the Enabled property to allow the contents to be copied and ToolTips to be shown.

Parse query string in JavaScript

Following on from my comment to the answer @bobby posted, here is the code I would use:

    function parseQuery(str)
        if(typeof str != "string" || str.length == 0) return {};
        var s = str.split("&");
        var s_length = s.length;
        var bit, query = {}, first, second;
        for(var i = 0; i < s_length; i++)
            bit = s[i].split("=");
            first = decodeURIComponent(bit[0]);
            if(first.length == 0) continue;
            second = decodeURIComponent(bit[1]);
            if(typeof query[first] == "undefined") query[first] = second;
            else if(query[first] instanceof Array) query[first].push(second);
            else query[first] = [query[first], second]; 
        return query;

This code takes in the querystring provided (as 'str') and returns an object. The string is split on all occurances of &, resulting in an array. the array is then travsersed and each item in it is split by "=". This results in sub arrays wherein the 0th element is the parameter and the 1st element is the value (or undefined if no = sign). These are mapped to object properties, so for example the string "hello=1&another=2&something" is turned into:

hello: "1",
another: "2",
something: undefined

In addition, this code notices repeating reoccurances such as "hello=1&hello=2" and converts the result into an array, eg:

hello: ["1", "2"]

You'll also notice it deals with cases in whih the = sign is not used. It also ignores if there is an equal sign straight after an & symbol.

A bit overkill for the original question, but a reusable solution if you ever need to work with querystrings in javascript :)

Check if a string has white space

Your regex won't match anything, as it is. You definitely need to remove the quotes -- the "/" characters are sufficient.

/^\s+$/ is checking whether the string is ALL whitespace:

  • ^ matches the start of the string.
  • \s+ means at least 1, possibly more, spaces.
  • $ matches the end of the string.

Try replacing the regex with /\s/ (and no quotes)

How do I remove all non-ASCII characters with regex and Notepad++?

To keep new lines:

  1. First select a character for new line... I used #.
  2. Select replace option, extended.
  3. input \n replace with #
  4. Hit Replace All


  1. Select Replace option Regular Expression.
  2. Input this : [^\x20-\x7E]+
  3. Keep Replace With Empty
  4. Hit Replace All

Now, Select Replace option Extended and Replace # with \n

:) now, you have a clean ASCII file ;)

The type or namespace name 'System' could not be found

Unload project -> Reload project normally fixes this weird, Nuget related, error to me.

sass :first-child not working

While @Andre is correct that there are issues with pseudo elements and their support, especially in older (IE) browsers, that support is improving all the time.

As for your question of, are there any issues, I'd say I've not really seen any, although the syntax for the pseudo-element can be a bit tricky, especially when first sussing it out. So:

  declarations: ...
    declarations: ...
      declarations: ...

which compiles as one would expect:

  declarations... }
div#top-level div.inside {
  declarations... }
div#top-level div.inside:first-child {
  declarations... }

I haven't seen any documentation on any of this, save for the statement that "sass can do everything that css can do." As always, with Haml and SASS the indentation is everything.

How to unzip a list of tuples into individual lists?

If you want a list of lists:

>>> [list(t) for t in zip(*l)]
[[1, 3, 8], [2, 4, 9]]

If a list of tuples is OK:

>>> zip(*l)
[(1, 3, 8), (2, 4, 9)]

How can I create a border around an Android LinearLayout?

Don't want to create a drawable resource?



      <TextView ... />

Is there a numpy builtin to reject outliers from a list

I wanted to do something similar, except setting the number to NaN rather than removing it from the data, since if you remove it you change the length which can mess up plotting (i.e. if you're only removing outliers from one column in a table, but you need it to remain the same as the other columns so you can plot them against each other).

To do so I used numpy's masking functions:

def reject_outliers(data, m=2):
    stdev = np.std(data)
    mean = np.mean(data)
    maskMin = mean - stdev * m
    maskMax = mean + stdev * m
    mask =, maskMin, maskMax)
    print('Masking values outside of {} and {}'.format(maskMin, maskMax))
    return mask

How to iterate through a table rows and get the cell values using jQuery

You got your answer, but why iterate over the tr when you can go straight for the inputs? That way you can store them easier into an array and it reduce the number of CSS queries. Depends what you want to do of course, but for collecting data it is a more flexible approach.

var array = [];

$("tr.item input").each(function() {
        name: $(this).attr('class'),
        value: $(this).val()


Convert byte[] to char[]

byte[] a = new byte[50];

char [] cArray= System.Text.Encoding.ASCII.GetString(a).ToCharArray();

From the URL thedixon posted

You cannot ToCharArray the byte without converting it to a string first.

To quote Jon Skeet there

There's no need for the copying here - just use Encoding.GetChars. However, there's no guarantee that ASCII is going to be the appropriate encoding to use.