Programs & Examples On #Utility

Utility software is system software designed to help analyze, configure, optimize or maintain a computer. A single piece of utility software is usually called a utility or tool.

Converting newline formatting from Mac to Windows

Expanding on the answers of Anne and JosephH, using perl in a short perl script, since i'm too lazy to type the perl-one-liner very time.
Create a file, named for example "unix2dos.pl" and put it in a directory in your path. Edit the file to contain the 2 lines:

#!/usr/bin/perl -wpi
s/\n|\r\n/\r\n/g;

Assuming that "which perl" returns "/usr/bin/perl" on your system. Make the file executable (chmod u+x unix2dos.pl).

Example:
$ echo "hello" > xxx
$ od -c xxx (checking that the file ends with a nl)
0000000 h e l l o \n

$ unix2dos.pl xxx
$ od -c xxx (checking that it ends now in cr lf)
0000000 h e l l o \r \n

Good tool for testing socket connections?

In situations like this, why not write your own? A simple server app to test connections can be done in a matter of minutes if you know what you're doing, and you can make it respond exactly how you need to, and for specific scenarios.

Java: Static Class?

Sounds like you have a utility class similar to java.lang.Math.
The approach there is final class with private constructor and static methods.

But beware of what this does for testability, I recommend reading this article
Static Methods are Death to Testability

How can I create an utility class?

I would make the class final and every method would be static.

So the class cannot be extended and the methods can be called by Classname.methodName. If you add members, be sure that they work thread safe ;)

Implement touch using Python?

Looks like this is new as of Python 3.4 - pathlib.

from pathlib import Path

Path('path/to/file.txt').touch()

This will create a file.txt at the path.

--

Path.touch(mode=0o777, exist_ok=True)

Create a file at this given path. If mode is given, it is combined with the process’ umask value to determine the file mode and access flags. If the file already exists, the function succeeds if exist_ok is true (and its modification time is updated to the current time), otherwise FileExistsError is raised.

Google Maps Android API v2 - Interactive InfoWindow (like in original android google maps)

Here's my take on the problem. I create AbsoluteLayout overlay which contains Info Window (a regular view with every bit of interactivity and drawing capabilities). Then I start Handler which synchronizes the info window's position with position of point on the map every 16 ms. Sounds crazy, but actually works.

Demo video: https://www.youtube.com/watch?v=bT9RpH4p9mU (take into account that performance is decreased because of emulator and video recording running simultaneously).

Code of the demo: https://github.com/deville/info-window-demo

An article providing details (in Russian): http://habrahabr.ru/post/213415/

How to read a list of files from a folder using PHP?

You can use standard directory functions

$dir = opendir('/tmp');
while ($file = readdir($dir)) {
    if ($file == '.' || $file == '..') {
        continue;
    }

    echo $file;
}
closedir($dir);

UILabel is not auto-shrinking text to fit label size

This is how I get UILabel Autoshrink work (especially for height of label font fitting in 4s device from 6s Plus Storyboard) in iOS 9.2, Xcode 7.2 ...

enter image description here

  • Number of lines is 0
  • Line Breaks: Clip
  • Autoshrink: Minimum Font Scale 0.25

How to terminate a process in vbscript

The Win32_Process class provides access to both 32-bit and 64-bit processes when the script is run from a 64-bit command shell.

If this is not an option for you, you can try using the taskkill command:

Dim oShell : Set oShell = CreateObject("WScript.Shell")

' Launch notepad '
oShell.Run "notepad"
WScript.Sleep 3000

' Kill notepad '
oShell.Run "taskkill /im notepad.exe", , True

SQL Server : Transpose rows to columns

I had a slightly different requirement, whereby I had to selectively transpose columns into rows.

The table had columns:

create table tbl (ID, PreviousX, PreviousY, CurrentX, CurrentY)

I needed columns for Previous and Current, and rows for X and Y. A Cartesian product generated on a static table worked nicely, eg:

select 
    ID,
    max(case when metric='X' then PreviousX
        case when metric='Y' then PreviousY end) as Previous,
    max(case when metric='X' then CurrentX
        case when metric='Y' then CurrentY end) as Current
from tbl inner join
    /* Cartesian product - transpose by repeating row and 
    picking appropriate metric column for period */
    ( VALUES (1, 'X'), (2, 'Y')) AS x (sort, metric) ON 1=1
group by ID
order by ID, sort

jQuery UI Accordion Expand/Collapse All

As discussed in the jQuery UI forums, you should not use accordions for this.

If you want something that looks and acts like an accordion, that is fine. Use their classes to style them, and implement whatever functionality you need. Then adding a button to open or close them all is pretty straightforward. Example

HTML

By using the jquery-ui classes, we keep our accordions looking just like the "real" accordions.

<div id="accordion" class="ui-accordion ui-widget ui-helper-reset">
    <h3 class="accordion-header ui-accordion-header ui-helper-reset ui-state-default ui-accordion-icons ui-corner-all">
        <span class="ui-accordion-header-icon ui-icon ui-icon-triangle-1-e"></span>
        Section 1
    </h3>
    <div class="ui-accordion-content ui-helper-reset ui-widget-content ui-corner-bottom">
        Content 1
    </div>
</div>?

Roll your own accordions

Mostly we just want accordion headers to toggle the state of the following sibling, which is it's content area. We have also added two custom events "show" and "hide" which we will hook into later.

var headers = $('#accordion .accordion-header');
var contentAreas = $('#accordion .ui-accordion-content ').hide();
var expandLink = $('.accordion-expand-all');

headers.click(function() {
    var panel = $(this).next();
    var isOpen = panel.is(':visible');

    // open or close as necessary
    panel[isOpen? 'slideUp': 'slideDown']()
        // trigger the correct custom event
        .trigger(isOpen? 'hide': 'show');

    // stop the link from causing a pagescroll
    return false;
});

Expand/Collapse All

We use a boolean isAllOpen flag to mark when the button has been changed, this could just as easily have been a class, or a state variable on a larger plugin framework.

expandLink.click(function(){
    var isAllOpen = $(this).data('isAllOpen');

    contentAreas[isAllOpen? 'hide': 'show']()
        .trigger(isAllOpen? 'hide': 'show');
});

Swap the button when "all open"

Thanks to our custom "show" and "hide" events, we have something to listen for when panels are changing. The only special case is "are they all open", if yes the button should be a "Collapse all", if not it should be "Expand all".

contentAreas.on({
    // whenever we open a panel, check to see if they're all open
    // if all open, swap the button to collapser
    show: function(){
        var isAllOpen = !contentAreas.is(':hidden');   
        if(isAllOpen){
            expandLink.text('Collapse All')
                .data('isAllOpen', true);
        }
    },
    // whenever we close a panel, check to see if they're all open
    // if not all open, swap the button to expander
    hide: function(){
        var isAllOpen = !contentAreas.is(':hidden');
        if(!isAllOpen){
            expandLink.text('Expand all')
            .data('isAllOpen', false);
        } 
    }
});?

Edit for comment: Maintaining "1 panel open only" unless you hit the "Expand all" button is actually much easier. Example

Select n random rows from SQL Server table

The server-side processing language in use (eg PHP, .net, etc) isn't specified, but if it's PHP, grab the required number (or all the records) and instead of randomising in the query use PHP's shuffle function. I don't know if .net has an equivalent function but if it does then use that if you're using .net

ORDER BY RAND() can have quite a performance penalty, depending on how many records are involved.

How to stretch a table over multiple pages

You should \usepackage{longtable}.

httpd-xampp.conf: How to allow access to an external IP besides localhost?

allow from all will not work along with Require local. Instead, try Require ip xxx.xxx.xxx.xx

For Example:

# New XAMPP security concept
#
<LocationMatch "^/(?i:(?:xampp|security|licenses|phpmyadmin|webalizer|server-status|server-info))">
    Require local
    Require ip 10.0.0.1
    ErrorDocument 403 /error/XAMPP_FORBIDDEN.html.var
</LocationMatch>

How to name variables on the fly?

Use assign:

assign(paste("orca", i, sep = ""), list_name[[i]])

jquery multiple checkboxes array

var checkedString = $('input:checkbox:checked.name').map(function() { return this.value; }).get().join();

How to import js-modules into TypeScript file?

I've been facing this problem for long but what this solves my problem Go inside the tsconfig.json and add the following under compilerOptions

{
  "compilerOptions": {
      ...
      "allowJs": true
      ...
  }
}

How do I make a C++ macro behave like a function?

Create a block using

 #define MACRO(...) do { ... } while(false)

Do not add a ; after the while(false)

How to change MySQL data directory?

This solution works in Windows 7 using Workbench. You will need Administrator privileges to do this. It creates a junction (like a shortcut) to wherever you really want to store your data

Open Workbench and select INSTANCE - Startup / Shutdown Stop the server

Install Junction Master from https://bitsum.com/junctionmaster.php

Navigate to C:\ProgramData\MySQL\MySQL Server 5.6

Right click on Data and select "MOVE and then LINK folder to ..." Accept the warning Point destination to "Your new data directory here without the quotes" Click MOVE AND LINK

Now go to "Your new data directory here without the quotes"

Right click on Data Go to the security tab Click Edit Click Add Type NETWORK SERVICE then Check Names Click OK Click the Allow Full Control checkbox and then OK

Go back to Workbench and Start the server

This method worked for me using MySQL Workbench 6.2 on Windows 7 Enterprise.

How can I use a DLL file from Python?

Maybe with Dispatch:

from win32com.client import Dispatch

zk = Dispatch("zkemkeeper.ZKEM") 

Where zkemkeeper is a registered DLL file on the system... After that, you can access functions just by calling them:

zk.Connect_Net(IP_address, port)

How to do this in Laravel, subquery where in

Please try this online tool sql2builder

DB::table('products')
    ->whereIn('products.id',function($query) {
                            DB::table('product_category')
                            ->whereIn('category_id',['223','15'])
                            ->select('product_id');
                        })
    ->where('products.active',1)
    ->select('products.id','products.name','products.img','products.safe_name','products.sku','products.productstatusid')
    ->get();

Can't find keyplane that supports type 4 for keyboard iPhone-Portrait-NumberPad; using 3876877096_Portrait_iPhone-Simple-Pad_Default

I also had this problem and found the solution.

Below is the code which will work for iOS 8.0 and also for below versions.

I have tested it on iOS 7 and 8.0 (Xcode Version 6.0.1)

- (void)addButtonToKeyboard
    {
    // create custom button
    self.doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
            //This code will work on iOS 8.3 and 8.4. 
       if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.3) {
            self.doneButton.frame = CGRectMake(0, [[UIScreen mainScreen]   bounds].size.height - 53, 106, 53);
      } else {
           self.doneButton.frame = CGRectMake(0, 163+44, 106, 53);
      }

    self.doneButton.adjustsImageWhenHighlighted = NO;
    [self.doneButton setTag:67123];
    [self.doneButton setImage:[UIImage imageNamed:@"doneup1.png"] forState:UIControlStateNormal];
    [self.doneButton setImage:[UIImage imageNamed:@"donedown1.png"] forState:UIControlStateHighlighted];

    [self.doneButton addTarget:self action:@selector(doneButton:) forControlEvents:UIControlEventTouchUpInside];

    // locate keyboard view
    int windowCount = [[[UIApplication sharedApplication] windows] count];
    if (windowCount < 2) {
        return;
    }

    UIWindow *tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];
    UIView *keyboard;

    for (int i = 0; i < [tempWindow.subviews count]; i++) {
        keyboard = [tempWindow.subviews objectAtIndex:i];
             // keyboard found, add the button
          if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.3) {

            UIButton *searchbtn = (UIButton *)[keyboard viewWithTag:67123];
            if (searchbtn == nil)
                [keyboard addSubview:self.doneButton];

            } else {   
                if([[keyboard description] hasPrefix:@"<UIPeripheralHost"] == YES) {
              UIButton *searchbtn = (UIButton *)[keyboard viewWithTag:67123];
                   if (searchbtn == nil)//to avoid adding again and again as per my requirement (previous and next button on keyboard)
                [keyboard addSubview:self.doneButton];

        } //This code will work on iOS 8.0
        else if([[keyboard description] hasPrefix:@"<UIInputSetContainerView"] == YES) {

            for (int i = 0; i < [keyboard.subviews count]; i++)
            {
                UIView *hostkeyboard = [keyboard.subviews objectAtIndex:i];

                if([[hostkeyboard description] hasPrefix:@"<UIInputSetHost"] == YES) {
                    UIButton *donebtn = (UIButton *)[hostkeyboard viewWithTag:67123];
                    if (donebtn == nil)//to avoid adding again and again as per my requirement (previous and next button on keyboard)
                        [hostkeyboard addSubview:self.doneButton];
                }
            }
        }
      }
    }
 }

>

- (void)removedSearchButtonFromKeypad 
    {

    int windowCount = [[[UIApplication sharedApplication] windows] count];
    if (windowCount < 2) {
        return;
    }

    UIWindow *tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];

    for (int i = 0 ; i < [tempWindow.subviews count] ; i++)
    {
        UIView *keyboard = [tempWindow.subviews objectAtIndex:i];

           if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.3){
                [self removeButton:keyboard];                  
            } else if([[keyboard description] hasPrefix:@"<UIPeripheralHost"] == YES) {
                  [self removeButton:keyboard];

             } else if([[keyboard description] hasPrefix:@"<UIInputSetContainerView"] == YES){

            for (int i = 0 ; i < [keyboard.subviews count] ; i++)
            {
                UIView *hostkeyboard = [keyboard.subviews objectAtIndex:i];

                if([[hostkeyboard description] hasPrefix:@"<UIInputSetHost"] == YES) {
                    [self removeButton:hostkeyboard];
                }
            }
        }
    }
}


- (void)removeButton:(UIView *)keypadView 
    {
    UIButton *donebtn = (UIButton *)[keypadView viewWithTag:67123];
    if(donebtn) {
        [donebtn removeFromSuperview];
        donebtn = nil;
    }
}

Hope this helps.

But , I still getting this warning:

Can't find keyplane that supports type 4 for keyboard iPhone-Portrait-NumberPad; using 3876877096_Portrait_iPhone-Simple-Pad_Default

Ignoring this warning, I got it working. Please, let me know if you able to get relief from this warning.

Priority queue in .Net

I found one by Julian Bucknall on his blog here - http://www.boyet.com/Articles/PriorityQueueCSharp3.html

We modified it slightly so that low-priority items on the queue would eventually 'bubble-up' to the top over time, so they wouldn't suffer starvation.

Git commit with no commit message

When working on an important code update, if you really need an intermediate safepoint you might just do:

git commit -am'.'

or shorter:

git commit -am.

How to detect Safari, Chrome, IE, Firefox and Opera browser?

Short variant (update 10 july 2020 mobile browser detection fix)

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var browser = (function() {
    var test = function(regexp) {return regexp.test(window.navigator.userAgent)}
    switch (true) {
        case test(/edg/i): return "Microsoft Edge";
        case test(/trident/i): return "Microsoft Internet Explorer";
        case test(/firefox|fxios/i): return "Mozilla Firefox";
        case test(/opr\//i): return "Opera";
        case test(/ucbrowser/i): return "UC Browser";
        case test(/samsungbrowser/i): return "Samsung Browser";
        case test(/chrome|chromium|crios/i): return "Google Chrome";
        case test(/safari/i): return "Apple Safari";
        default: return "Other";
    }
})();
console.log(browser)
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How to check if input date is equal to today's date?

The Best way and recommended way of comparing date in typescript is:

var today = new Date().getTime();
var reqDateVar = new Date(somedate).getTime();

if(today === reqDateVar){
 // NOW
} else {
 // Some other time
}

Indent multiple lines quickly in vi

Use the > command. To indent five lines, 5>>. To mark a block of lines and indent it, Vjj> to indent three lines (Vim only). To indent a curly-braces block, put your cursor on one of the curly braces and use >% or from anywhere inside block use >iB.

If you’re copying blocks of text around and need to align the indent of a block in its new location, use ]p instead of just p. This aligns the pasted block with the surrounding text.

Also, the shiftwidth setting allows you to control how many spaces to indent.

Create a hexadecimal colour based on a string with JavaScript

If your inputs are not different enough for a simple hash to use the entire color spectrum, you can use a seeded random number generator instead of a hash function.

I'm using the color coder from Joe Freeman's answer, and David Bau's seeded random number generator.

function stringToColour(str) {
    Math.seedrandom(str);
    var rand = Math.random() * Math.pow(255,3);
    Math.seedrandom(); // don't leave a non-random seed in the generator
    for (var i = 0, colour = "#"; i < 3; colour += ("00" + ((rand >> i++ * 8) & 0xFF).toString(16)).slice(-2));
    return colour;
}

How to smooth a curve in the right way?

Fitting a moving average to your data would smooth out the noise, see this this answer for how to do that.

If you'd like to use LOWESS to fit your data (it's similar to a moving average but more sophisticated), you can do that using the statsmodels library:

import numpy as np
import pylab as plt
import statsmodels.api as sm

x = np.linspace(0,2*np.pi,100)
y = np.sin(x) + np.random.random(100) * 0.2
lowess = sm.nonparametric.lowess(y, x, frac=0.1)

plt.plot(x, y, '+')
plt.plot(lowess[:, 0], lowess[:, 1])
plt.show()

Finally, if you know the functional form of your signal, you could fit a curve to your data, which would probably be the best thing to do.

Explode PHP string by new line

this php function explode string by newline

Attention : new line in Windows is \r\n and in Linux and Unix is \n
this function change all new lines to linux mode then split it.
pay attention that empty lines will be ignored

function splitNewLine($text) {
    $code=preg_replace('/\n$/','',preg_replace('/^\n/','',preg_replace('/[\r\n]+/',"\n",$text)));
    return explode("\n",$code);
}

example

$a="\r\n\r\n\n\n\r\rsalam\r\nman khobam\rto chi\n\rche khabar\n\r\n\n\r\r\n\nbashe baba raftam\r\n\r\n\r\n\r\n";
print_r( splitNewLine($a) );

output

Array
(
    [0] => salam
    [1] => man khobam
    [2] => to chi
    [3] => che khabar
    [4] => bashe baba raftam
)

Is there an R function for finding the index of an element in a vector?

A small note about the efficiency of abovementioned methods:

 library(microbenchmark)

  microbenchmark(
    which("Feb" == month.abb)[[1]],
    which(month.abb %in% "Feb"))

  Unit: nanoseconds
   min     lq    mean median     uq  max neval
   891  979.0 1098.00   1031 1135.5 3693   100
   1052 1175.5 1339.74   1235 1390.0 7399  100

So, the best one is

    which("Feb" == month.abb)[[1]]

CSS – why doesn’t percentage height work?

Another option is to add style to div

<div style="position: absolute; height:somePercentage%; overflow:auto(or other overflow value)">
 //to be scrolled 
</div>

And it means that an element is positioned relative to the nearest positioned ancestor.

Reading a binary file with python

I too found Python lacking when it comes to reading and writing binary files, so I wrote a small module (for Python 3.6+).

With binaryfile you'd do something like this (I'm guessing, since I don't know Fortran):

import binaryfile

def particle_file(f):
    f.array('group_ids')  # Declare group_ids to be an array (so we can use it in a loop)
    f.skip(4)  # Bytes 1-4
    num_particles = f.count('num_particles', 'group_ids', 4)  # Bytes 5-8
    f.int('num_groups', 4)  # Bytes 9-12
    f.skip(8)  # Bytes 13-20
    for i in range(num_particles):
        f.struct('group_ids', '>f')  # 4 bytes x num_particles
    f.skip(4)

with open('myfile.bin', 'rb') as fh:
    result = binaryfile.read(fh, particle_file)
print(result)

Which produces an output like this:

{
    'group_ids': [(1.0,), (0.0,), (2.0,), (0.0,), (1.0,)],
    '__skipped': [b'\x00\x00\x00\x08', b'\x00\x00\x00\x08\x00\x00\x00\x14', b'\x00\x00\x00\x14'],
    'num_particles': 5,
    'num_groups': 3
}

I used skip() to skip the additional data Fortran adds, but you may want to add a utility to handle Fortran records properly instead. If you do, a pull request would be welcome.

How to alias a table in Laravel Eloquent queries (or using Query Builder)?

Laravel supports aliases on tables and columns with AS. Try

$users = DB::table('really_long_table_name AS t')
           ->select('t.id AS uid')
           ->get();

Let's see it in action with an awesome tinker tool

$ php artisan tinker
[1] > Schema::create('really_long_table_name', function($table) {$table->increments('id');});
// NULL
[2] > DB::table('really_long_table_name')->insert(['id' => null]);
// true
[3] > DB::table('really_long_table_name AS t')->select('t.id AS uid')->get();
// array(
//   0 => object(stdClass)(
//     'uid' => '1'
//   )
// )

Showing all session data at once?

print_r($this->session->userdata); 

or

print_r($this->session->all_userdata());

How do I return the response from an asynchronous call?

Here are some approaches to work with asynchronous requests:

  1. Browser Promise object
  2. Q - A promise library for JavaScript
  3. A+ Promises.js
  4. jQuery deferred
  5. XMLHttpRequest API
  6. Using callback concept - As implementation in first answer

Example: jQuery deferred implementation to work with multiple requests

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var App = App || {};

App = {
    getDataFromServer: function(){

      var self = this,
                 deferred = $.Deferred(),
                 requests = [];

      requests.push($.getJSON('request/ajax/url/1'));
      requests.push($.getJSON('request/ajax/url/2'));

      $.when.apply(jQuery, requests).done(function(xhrResponse) {
        return deferred.resolve(xhrResponse.result);
      });
      return deferred;
    },

    init: function(){

        this.getDataFromServer().done(_.bind(function(resp1, resp2) {

           // Do the operations which you wanted to do when you
           // get a response from Ajax, for example, log response.
        }, this));
    }
};
App.init();
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TERM environment variable not set

SOLVED: On Debian 10 by adding "EXPORT TERM=xterm" on the Script executed by CRONTAB (root) but executed as www-data.

$ crontab -e

*/15 * * * * /bin/su - www-data -s /bin/bash -c '/usr/local/bin/todos.sh'

FILE=/usr/local/bin/todos.sh

#!/bin/bash -p
export TERM=xterm && cd /var/www/dokuwiki/data/pages && clear && grep -r -h '|(TO-DO)' > /var/www/todos.txt && chmod 664 /var/www/todos.txt && chown www-data:www-data /var/www/todos.txt

JQuery post JSON object to a server

To send json to the server, you first have to create json

function sendData() {
    $.ajax({
        url: '/helloworld',
        type: 'POST',
        contentType: 'application/json',
        data: JSON.stringify({
            name:"Bob",
            ...
        }),
        dataType: 'json'
    });
}

This is how you would structure the ajax request to send the json as a post var.

function sendData() {
    $.ajax({
        url: '/helloworld',
        type: 'POST',
        data: { json: JSON.stringify({
            name:"Bob",
            ...
        })},
        dataType: 'json'
    });
}

The json will now be in the json post var.

How to copy file from HDFS to the local file system

In Hadoop 2.0,

hdfs dfs -copyToLocal <hdfs_input_file_path> <output_path>

where,

  • hdfs_input_file_path maybe obtained from http://<<name_node_ip>>:50070/explorer.html

  • output_path is the local path of the file, where the file is to be copied to.

  • you may also use get in place of copyToLocal.

java.io.IOException: Invalid Keystore format

Your keystore is broken, and you will have to restore or regenerate it.

PostgreSQL create table if not exists

Try this:

CREATE TABLE IF NOT EXISTS app_user (
  username varchar(45) NOT NULL,
  password varchar(450) NOT NULL,
  enabled integer NOT NULL DEFAULT '1',
  PRIMARY KEY (username)
)

How do I get sed to read from standard input?

use "-e" to specify the sed-expression

cat input.txt | sed -e 's/foo/bar/g'

Deep copy an array in Angular 2 + TypeScript

Here is my own. Doesn't work for complex cases, but for a simple array of Objects, it's good enough.

  deepClone(oldArray: Object[]) {
    let newArray: any = [];
    oldArray.forEach((item) => {
      newArray.push(Object.assign({}, item));
    });
    return newArray;
  }

Regular Expression to find a string included between two characters while EXCLUDING the delimiters

Most updated solution

If you are using Javascript, the best solution that I came up with is using match instead of exec method. Then, iterate matches and remove the delimiters with the result of the first group using $1

const text = "This is a test string [more or less], [more] and [less]";
const regex = /\[(.*?)\]/gi;
const resultMatchGroup = text.match(regex); // [ '[more or less]', '[more]', '[less]' ]
const desiredRes = resultMatchGroup.map(match => match.replace(regex, "$1"))
console.log("desiredRes", desiredRes); // [ 'more or less', 'more', 'less' ]

As you can see, this is useful for multiple delimiters in the text as well

Force DOM redraw/refresh on Chrome/Mac

I wanted to return all the states to the previous state (without reloading) including the elements added by jquery. The above implementation not gonna works. and I did as follows.

// Set initial HTML description
var defaultHTML;
function DefaultSave() {
  defaultHTML = document.body.innerHTML;
}
// Restore HTML description to initial state
function HTMLRestore() {
  document.body.innerHTML = defaultHTML;
}



DefaultSave()
<input type="button" value="Restore" onclick="HTMLRestore()">

Convert HTML Character Back to Text Using Java Standard Library

You can use the class org.apache.commons.lang.StringEscapeUtils:

String s = StringEscapeUtils.unescapeHtml("Happy &amp; Sad")

It is working.

Difference between "and" and && in Ruby?

The practical difference is binding strength, which can lead to peculiar behavior if you're not prepared for it:

foo = :foo
bar = nil

a = foo and bar
# => nil
a
# => :foo

a = foo && bar
# => nil
a
# => nil

a = (foo and bar)
# => nil
a
# => nil

(a = foo) && bar
# => nil
a
# => :foo

The same thing works for || and or.

Unsupported method: BaseConfig.getApplicationIdSuffix()

First, open your application module build.gradle file.

Check the classpath according to your project dependency. If not change the version of this classpath.

from:

classpath 'com.android.tools.build:gradle:1.0.0'

To:

classpath 'com.android.tools.build:gradle:2.3.2'

or higher version according to your gradle of android studio.

If its still problem, then change buildToolsVersion:

From:

buildToolsVersion '21.0.0'

To:

buildToolsVersion '25.0.0'

then hit 'Try again' and gradle will automatically sync. This will solve it.

<hr> tag in Twitter Bootstrap not functioning correctly?

By default, the hr element in Twitter Bootstrap CSS file has a top and bottom margin of 18px. That's what creates a gap. If you want the gap to be smaller you'll need to adjust margin property of the hr element.

In your example, do something like this:

.container hr {
margin: 2px 0;
}

Authentication failed to bitbucket

For Mac Users. There was a default account set on the Source tree which does not allow me to clone the URL because my current URL was of different bitbucket account. So, It shows the invalid source path and I then click on Advance Options and found Authentication failed to your_clone_url. So, follow these steps

  1. Select Source Tree. Go to SourceTree menu -> Select Preferences.
  2. It will show Accounts window. Then Choose Accounts enter image description here

Here it will show list of your added accounts. Just click on Add button from the bottom and add your new bitbucket account details. It will list you account under Accounts tab. You can also set default account by clicking on Set Default .. button from bottom. Now all is done.

websocket.send() parameter

As I understand it, you want the server be able to send messages through from client 1 to client 2. You cannot directly connect two clients because one of the two ends of a WebSocket connection needs to be a server.

This is some pseudocodish JavaScript:

Client:

var websocket = new WebSocket("server address");

websocket.onmessage = function(str) {
  console.log("Someone sent: ", str);
};

// Tell the server this is client 1 (swap for client 2 of course)
websocket.send(JSON.stringify({
  id: "client1"
}));

// Tell the server we want to send something to the other client
websocket.send(JSON.stringify({
  to: "client2",
  data: "foo"
}));

Server:

var clients = {};

server.on("data", function(client, str) {
  var obj = JSON.parse(str);

  if("id" in obj) {
    // New client, add it to the id/client object
    clients[obj.id] = client;
  } else {
    // Send data to the client requested
    clients[obj.to].send(obj.data);
  }
});

The transaction manager has disabled its support for remote/network transactions

Make sure that the "Distributed Transaction Coordinator" Service is running on both database and client. Also make sure you check "Network DTC Access", "Allow Remote Client", "Allow Inbound/Outbound" and "Enable TIP".

To enable Network DTC Access for MS DTC transactions

  1. Open the Component Services snap-in.

    To open Component Services, click Start. In the search box, type dcomcnfg, and then press ENTER.

  2. Expand the console tree to locate the DTC (for example, Local DTC) for which you want to enable Network MS DTC Access.

  3. On the Action menu, click Properties.

  4. Click the Security tab and make the following changes: In Security Settings, select the Network DTC Access check box.

    In Transaction Manager Communication, select the Allow Inbound and Allow Outbound check boxes.

When do items in HTML5 local storage expire?

For the benefit of searchers:

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

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

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

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

// Removal of all expired items
if(window.localStorage){

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

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

        if(lastRow && parseInt(lastRow) < expiryTime){
            deleteRows.push(key);
        }
    }
    // delete old data
    for(var j=0; j < deleteRows.length; j++){
        localStorage.removeItem(deleteRows[j]);
    }
}

Change visibility of ASP.NET label with JavaScript

Continuing with what Dave Ward said:

  • You can't set the Visible property to false because the control will not be rendered.
  • You should use the Style property to set it's display to none.

Page/Control design

<asp:Label runat="server" ID="Label1" Style="display: none;" />

<asp:Button runat="server" ID="Button1" />

Code behind

Somewhere in the load section:

Label label1 = (Label)FindControl("Label1");
((Label)FindControl("Button1")).OnClientClick = "ToggleVisibility('" + label1.ClientID + "')";

Javascript file

function ToggleVisibility(elementID)
{
    var element = document.getElementByID(elementID);

    if (element.style.display = 'none')
    {
        element.style.display = 'inherit';
    }
    else
    {
        element.style.display = 'none';
    }
}

Of course, if you don't want to toggle but just to show the button/label then adjust the javascript method accordingly.

The important point here is that you need to send the information about the ClientID of the control that you want to manipulate on the client side to the javascript file either setting global variables or through a function parameter as in my example.

How to add a "open git-bash here..." context menu to the windows explorer?

What worked for me was almost this, but with the following REGEDIT path:
HKEY_LOCAL_MACHINE/SOFTWARE/Classes/Directory/background/shell and here I created the key Bash, with the value of what I want the display name to be, and then created another key under this named command with the value as the path to git-bash.exe

I'm on Windows 10 and have a fresh git install that didn't add this automatically for some reason (git version 2.12.0 64bit)

How to delete an instantiated object Python?

What do you mean by delete? In Python, removing a reference (or a name) can be done with the del keyword, but if there are other names to the same object that object will not be deleted.

--> test = 3
--> print(test)
3
--> del test
--> print(test)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'test' is not defined

compared to:

--> test = 5
--> other is test  # check that both name refer to the exact same object
True
--> del test       # gets rid of test, but the object is still referenced by other
--> print(other)
5

Compare every item to every other item in ArrayList

This code helped me get this behaviour: With a list a,b,c, I should get compared ab, ac and bc, but any other pair would be excess / not needed.

import java.util.*;
import static java.lang.System.out;

// rl = rawList; lr = listReversed
ArrayList<String> rl = new ArrayList<String>();
ArrayList<String> lr = new ArrayList<String>();
rl.add("a");
rl.add("b");
rl.add("c");
rl.add("d");
rl.add("e");
rl.add("f");

lr.addAll(rl);
Collections.reverse(lr);

for (String itemA : rl) {
    lr.remove(lr.size()-1);
        for (String itemZ : lr) {
        System.out.println(itemA + itemZ);
    }
}

The loop goes as like in this picture: Triangular comparison visual example

or as this:

   |   f    e    d    c    b   a
   ------------------------------
a  |  af   ae   ad   ac   ab   ·
b  |  bf   be   bd   bc   ·   
c  |  cf   ce   cd   ·      
d  |  df   de   ·         
e  |  ef   ·            
f  |  ·               

total comparisons is a triangular number (n * n-1)/2

Assign variable in if condition statement, good practice or not?

There is one case when you do it, with while-loops.
When reading files, you usualy do like this:

void readFile(String pathToFile) {
    // Create a FileInputStream object
    FileInputStream fileIn = null;
    try {
        // Create the FileInputStream
        fileIn = new FileInputStream(pathToFile);
        // Create a variable to store the current line's text in
        String currentLine;
        // While the file has lines left, read the next line,
        // store it in the variable and do whatever is in the loop
        while((currentLine = in.readLine()) != null) {
            // Print out the current line in the console
            // (you can do whatever you want with the line. this is just an example)
            System.out.println(currentLine);
        }
    } catch(IOException e) {
        // Handle exception
    } finally {
        try {
            // Close the FileInputStream
            fileIn.close();
        } catch(IOException e) {
            // Handle exception
        }
    }
}

Look at the while-loop at line 9. There, a new line is read and stored in a variable, and then the content of the loop is ran. I know this isn't an if-statement, but I guess a while loop can be included in your question as well.

The reason to this is that when using a FileInputStream, every time you call FileInputStream.readLine(), it reads the next line in the file, so if you would have called it from the loop with just fileIn.readLine() != null without assigning the variable, instead of calling (currentLine = fileIn.readLine()) != null, and then called it from inside of the loop too, you would only get every second line.

Hope you understand, and good luck!

Where to declare variable in react js

Assuming that onMove is an event handler, it is likely that its context is something other than the instance of MyContainer, i.e. this points to something different.

You can manually bind the context of the function during the construction of the instance via Function.bind:

class MyContainer extends Component {
  constructor(props) {
    super(props);

    this.onMove = this.onMove.bind(this);

    this.test = "this is a test";
  }

  onMove() {
    console.log(this.test);
  }
}

Also, test !== testVariable.

unknown type name 'uint8_t', MinGW

To use uint8_t type alias, you have to include stdint.h standard header.

The entity type <type> is not part of the model for the current context

The problem may be in the connection string. Ensure your connection string is for SqlClient provider, with no metadata stuff related to EntityFramework.

How to insert date values into table

date must be insert with two apostrophes' As example if the date is 2018/10/20. It can insert from these query

Query -

insert into run(id,name,dob)values(&id,'&name','2018-10-20')

php how to go one level up on dirname(__FILE__)

You could use PHP's dirname function. <?php echo dirname(__DIR__); ?>. That will give you the name of the parent directory of __DIR__, which stores the current directory.

Unexpected character encountered while parsing value

Suppose this is your json

{
  "date":"11/05/2016",
  "venue": "{\"ID\":12,\"CITY\":Delhi}"
}

if you again want deserialize venue, modify json as below

{
  "date":"11/05/2016",
  "venue": "{\"ID\":\"12\",\"CITY\":\"Delhi\"}"
}

then try to deserialize to respective class by taking the value of venue

Media query to detect if device is touchscreen

In 2017, CSS media query from second answer still doesn't work on Firefox. I found a soluton for that: -moz-touch-enabled


So, here is cross-browser media query:

@media (-moz-touch-enabled: 1), (pointer:coarse) {
    .something {
        its: working;
    }
}

what is this value means 1.845E-07 in excel?

1.84E-07 is the exact value, represented using scientific notation, also known as exponential notation.

1.845E-07 is the same as 0.0000001845. Excel will display a number very close to 0 as 0, unless you modify the formatting of the cell to display more decimals.

C# however will get the actual value from the cell. The ToString method use the e-notation when converting small numbers to a string.

You can specify a format string if you don't want to use the e-notation.

Where is database .bak file saved from SQL Server Management Studio?

I dont think default backup location is stored within the SQL server itself. The settings are stored in Registry. Look for "BackupDirectory" key and you'll find the default backup.

The "msdb.dbo.backupset" table consists of list of backups taken, if no backup is taken for a database, it won't show you anything

What is the difference between JDK and JRE?

If you are a Java programmer you will need JDK in your system and this package will include JRE and JVM as well but if you are normal user who like to play online games then you will only need JRE and this package will not have JDK in it.

JVM

JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides runtime environment in which java bytecode can be executed.

JVMs are available for many hardware and software platforms. JVM, JRE and JDK are platform dependent because configuration of each OS differs. But, Java is platform independent.

JRE

It contains everything you need to run Java applications in compiled form. You don't need any libraries and other stuffs. All things you need are compiled.

JRE is can not used for development, only used for run the applications.

Java SE Development Kit (JDK)

The JDK includes the JRE plus command-line development tools such as compilers and debuggers that are necessary or useful for developing applets and applications.

(Sources: GeeksForGeeks Q&A, Java Platform Overview)

How do I merge a git tag onto a branch

I'm late to the game here, but another approach could be:

1) create a branch from the tag ($ git checkout -b [new branch name] [tag name])

2) create a pull-request to merge with your new branch into the destination branch

How can I transform string to UTF-8 in C#?

Use the below code snippet to get bytes from csv file

protected byte[] GetCSVFileContent(string fileName)
    {
        StringBuilder sb = new StringBuilder();
        using (StreamReader sr = new StreamReader(fileName, Encoding.Default, true))
        {
            String line;
            // Read and display lines from the file until the end of 
            // the file is reached.
            while ((line = sr.ReadLine()) != null)
            {
                sb.AppendLine(line);
            }
        }
        string allines = sb.ToString();


        UTF8Encoding utf8 = new UTF8Encoding();


        var preamble = utf8.GetPreamble();

        var data = utf8.GetBytes(allines);


        return data;
    }

Call the below and save it as an attachment

           Encoding csvEncoding = Encoding.UTF8;
                   //byte[] csvFile = GetCSVFileContent(FileUpload1.PostedFile.FileName);
          byte[] csvFile = GetCSVFileContent("Your_CSV_File_NAme");


        string attachment = String.Format("attachment; filename={0}.csv", "uomEncoded");

        Response.Clear();
        Response.ClearHeaders();
        Response.ClearContent();
        Response.ContentType = "text/csv";
        Response.ContentEncoding = csvEncoding;
        Response.AppendHeader("Content-Disposition", attachment);
        //Response.BinaryWrite(csvEncoding.GetPreamble());
        Response.BinaryWrite(csvFile);
        Response.Flush();
        Response.End();

RegisterStartupScript from code behind not working when Update Panel is used

You need to use ScriptManager.RegisterStartupScript for Ajax.

protected void ButtonPP_Click(object sender, EventArgs e) {     if (radioBtnACO.SelectedIndex < 0)     {         string csname1 = "PopupScript";          var cstext1 = new StringBuilder();         cstext1.Append("alert('Please Select Criteria!')");          ScriptManager.RegisterStartupScript(this, GetType(), csname1,             cstext1.ToString(), true);     } } 

How to send email to multiple recipients with addresses stored in Excel?

ToAddress = "[email protected]"
ToAddress1 = "[email protected]"
ToAddress2 = "[email protected]"
MessageSubject = "It works!."
Set ol = CreateObject("Outlook.Application")
Set newMail = ol.CreateItem(olMailItem)
newMail.Subject = MessageSubject
newMail.RecipIents.Add(ToAddress)
newMail.RecipIents.Add(ToAddress1)
newMail.RecipIents.Add(ToAddress2)
newMail.Send

ORA-12154 could not resolve the connect identifier specified

This is an old question but Oracle's latest installers are no improvement, so I recently found myself back in this swamp, thrashing around for several days ...

My scenario was SQL Server 2016 RTM. 32-bit Oracle 12c Open Client + ODAC was eventually working fine for Visual Studio Report Designer and Integration Services designer, and also SSIS packages run through SQL Server Agent (with 32-bit option). 64-bit was working fine for Report Portal when defining and Testing an Data Source, but running the reports always gave the dreaded "ORA-12154" error.

My final solution was to switch to an EZCONNECT connection string - this avoids the TNSNAMES mess altogether. Here's a link to a detailed description, but it's basically just: host:port/sid

http://www.oracledistilled.com/oracle-database/oracle-net/using-easy-connect-ezconnect-naming-method-to-connect-to-oracle-databases/

In case it helps anyone in the future (or I get stuck on this again), here are my Oracle install steps (the full horror):

Install Oracle drivers: Oracle Client 12c (32-bit) plus ODAC.

a. Download and unzip the following files from http://www.oracle.com/technetwork/database/enterprise-edition/downloads/database12c-win64-download-2297732.html and http://www.oracle.com/technetwork/database/windows/downloads/utilsoft-087491.html ):

i. winnt_12102_client32.zip

ii. ODAC112040Xcopy_32bit.zip

b. Run winnt_12102_client32\client32\setup.exe. For the Installation Type, choose Admin. For the installation location enter C:\Oracle\Oracle12. Accept other defaults.

c. Start a Command Prompt “As Administrator” and change directory (cd) to your ODAC112040Xcopy_32bit folder.

d. Enter the command: install.bat all C:\Oracle\Oracle12 odac

e. Copy the tnsnames.ora file from another machine to these folders: *

i. C:\Oracle\Oracle12\network\admin *

ii. C:\Oracle\Oracle12\product\12.1.0\client_1\network\admin *

Install Oracle Client 12c (x64) plus ODAC

a. Download and unzip the following files from http://www.oracle.com/technetwork/database/enterprise-edition/downloads/database12c-win64-download-2297732.html and http://www.oracle.com/technetwork/database/windows/downloads/index-090165.html ):

i. winx64_12102_client.zip

ii. ODAC121024Xcopy_x64.zip

b. Run winx64_12102_client\client\setup.exe. For the Installation Type, choose Admin. For the installation location enter C:\Oracle\Oracle12_x64. Accept other defaults.

c. Start a Command Prompt “As Administrator” and change directory (cd) to the C:\Software\Oracle Client\ODAC121024Xcopy_x64 folder.

d. Enter the command: install.bat all C:\Oracle\Oracle12_x64 odac

e. Copy the tnsnames.ora file from another machine to these folders: *

i. C:\Oracle\Oracle12_x64\network\admin *

ii. C:\Oracle\Oracle12_x64\product\12.1.0\client_1\network\admin *

* If you are going with the EZCONNECT method, then these steps are not required.

The ODAC installs are tricky and obscure - thanks to Dan English who gave me the method (detailed above) for that.

How to type in textbox using Selenium WebDriver (Selenium 2) with Java?

This is simple if you only use Selenium WebDriver, and forget the usage of Selenium-RC. I'd go like this.

WebDriver driver = new FirefoxDriver();
WebElement email = driver.findElement(By.id("email"));
email.sendKeys("[email protected]");

The reason for NullPointerException however is that your variable driver has never been started, you start FirefoxDriver in a variable wb thas is never being used.

CSS: How can I set image size relative to parent height?

Use max-width property of CSS, like this :

img{
  max-width:100%;
}

Changing website favicon dynamically

Here's some code I use to add dynamic favicon support to Opera, Firefox and Chrome. I couldn't get IE or Safari working though. Basically Chrome allows dynamic favicons, but it only updates them when the page's location (or an iframe etc in it) changes as far as I can tell:

var IE = navigator.userAgent.indexOf("MSIE")!=-1
var favicon = {
    change: function(iconURL) {
        if (arguments.length == 2) {
            document.title = optionalDocTitle}
        this.addLink(iconURL, "icon")
        this.addLink(iconURL, "shortcut icon")

        // Google Chrome HACK - whenever an IFrame changes location 
        // (even to about:blank), it updates the favicon for some reason
        // It doesn't work on Safari at all though :-(
        if (!IE) { // Disable the IE "click" sound
            if (!window.__IFrame) {
                __IFrame = document.createElement('iframe')
                var s = __IFrame.style
                s.height = s.width = s.left = s.top = s.border = 0
                s.position = 'absolute'
                s.visibility = 'hidden'
                document.body.appendChild(__IFrame)}
            __IFrame.src = 'about:blank'}},

    addLink: function(iconURL, relValue) {
        var link = document.createElement("link")
        link.type = "image/x-icon"
        link.rel = relValue
        link.href = iconURL
        this.removeLinkIfExists(relValue)
        this.docHead.appendChild(link)},

    removeLinkIfExists: function(relValue) {
        var links = this.docHead.getElementsByTagName("link");
        for (var i=0; i<links.length; i++) {
            var link = links[i]
            if (link.type == "image/x-icon" && link.rel == relValue) {
                this.docHead.removeChild(link)
                return}}}, // Assuming only one match at most.

    docHead: document.getElementsByTagName("head")[0]}

To change favicons, just go favicon.change("ICON URL") using the above.

(credits to http://softwareas.com/dynamic-favicons for the code I based this on.)

How to create python bytes object from long hex string?

result = bytes.fromhex(some_hex_string)

Pandas split column of lists into multiple columns

Much simpler solution:

pd.DataFrame(df2["teams"].to_list(), columns=['team1', 'team2'])

Yields,

  team1 team2
-------------
0    SF   NYG
1    SF   NYG
2    SF   NYG
3    SF   NYG
4    SF   NYG
5    SF   NYG
6    SF   NYG
7    SF   NYG

If you wanted to split a column of delimited strings rather than lists, you could similarly do:

pd.DataFrame(df["teams"].str.split('<delim>', expand=True).values,
             columns=['team1', 'team2'])

Is it possible to use raw SQL within a Spring Repository

It is possible to use raw query within a Spring Repository.

      @Query(value = "SELECT A.IS_MUTUAL_AID FROM planex AS A 
             INNER JOIN planex_rel AS B ON A.PLANEX_ID=B.PLANEX_ID  
             WHERE B.GOOD_ID = :goodId",nativeQuery = true)

      Boolean mutualAidFlag(@Param("goodId")Integer goodId);

How do I set a textbox's text to bold at run time?

Depending on your application, you'll probably want to use that Font assignment either on text change or focus/unfocus of the textbox in question.

Here's a quick sample of what it could look like (empty form, with just a textbox. Font turns bold when the text reads 'bold', case-insensitive):

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        RegisterEvents();
    }

    private void RegisterEvents()
    {
        _tboTest.TextChanged += new EventHandler(TboTest_TextChanged);
    }

    private void TboTest_TextChanged(object sender, EventArgs e)
    {
        // Change the text to bold on specified condition
        if (_tboTest.Text.Equals("Bold", StringComparison.OrdinalIgnoreCase))
        {
            _tboTest.Font = new Font(_tboTest.Font, FontStyle.Bold);
        }
        else
        {
            _tboTest.Font = new Font(_tboTest.Font, FontStyle.Regular);
        }
    }
}

Embed youtube videos that play in fullscreen automatically

This was pretty well answered over here: How to make a YouTube embedded video a full page width one?

If you add '?rel=0&autoplay=1' to the end of the url in the embed code (like this)

<iframe id="video" src="//www.youtube.com/embed/5iiPC-VGFLU?rel=0&autoplay=1" frameborder="0" allowfullscreen></iframe>

of the video it should play on load. Here's a demo over at jsfiddle.

select records from postgres where timestamp is in certain range

SELECT * 
FROM reservations 
WHERE arrival >= '2012-01-01'
AND arrival < '2013-01-01'
   ;

BTW if the distribution of values indicates that an index scan will not be the worth (for example if all the values are in 2012), the optimiser could still choose a full table scan. YMMV. Explain is your friend.

How to resolve ambiguous column names when retrieving results?

@Jason. You are correct except that php is the culprit and not mysql. If you put your JOIN in Mysql Workbench you will get three columns with the exact same name (one for each table) but not with the same data (some will be null if that table has no match for the JOIN).

In php if you use MYSQL_NUM in mysql_fetch_array() then you will get all columns. The problem is when you use mysql_fetch_array() with MYSQL_ASSOC. Then, inside that function, php is building the return value like so:

$row['dup'] = [value from table1]

and later on...

$row['dup'] = [value from table2]

...

$row['dup'] = [value from table3]

So you will get only the value from table3. The problem is that a result set from mysql can contain columns with the same name but associative arrays in php don't allow duplicate keys in arrays. When the data is saved in associative arrays, in php, some information is silently lost...

What is PostgreSQL equivalent of SYSDATE from Oracle?

NOW() is the replacement of Oracle Sysdate in Postgres.

Try "Select now()", it will give you the system timestamp.

Display progress bar while doing some work in C#?

And another example that BackgroundWorker is the right way to do it...

using System;
using System.ComponentModel;
using System.Threading;
using System.Windows.Forms;

namespace SerialSample
{
    public partial class Form1 : Form
    {
        private BackgroundWorker _BackgroundWorker;
        private Random _Random;

        public Form1()
        {
            InitializeComponent();
            _ProgressBar.Style = ProgressBarStyle.Marquee;
            _ProgressBar.Visible = false;
            _Random = new Random();

            InitializeBackgroundWorker();
        }

        private void InitializeBackgroundWorker()
        {
            _BackgroundWorker = new BackgroundWorker();
            _BackgroundWorker.WorkerReportsProgress = true;

            _BackgroundWorker.DoWork += (sender, e) => ((MethodInvoker)e.Argument).Invoke();
            _BackgroundWorker.ProgressChanged += (sender, e) =>
                {
                    _ProgressBar.Style = ProgressBarStyle.Continuous;
                    _ProgressBar.Value = e.ProgressPercentage;
                };
            _BackgroundWorker.RunWorkerCompleted += (sender, e) =>
            {
                if (_ProgressBar.Style == ProgressBarStyle.Marquee)
                {
                    _ProgressBar.Visible = false;
                }
            };
        }

        private void buttonStart_Click(object sender, EventArgs e)
        {
            _BackgroundWorker.RunWorkerAsync(new MethodInvoker(() =>
                {
                    _ProgressBar.BeginInvoke(new MethodInvoker(() => _ProgressBar.Visible = true));
                    for (int i = 0; i < 1000; i++)
                    {
                        Thread.Sleep(10);
                        _BackgroundWorker.ReportProgress(i / 10);
                    }
                }));
        }
    }
}

Problems using Maven and SSL behind proxy

Step 1: GET the contents of the Certificate of the website( you want to have it imported as a trusted root)

$ keytool -printcert -rfc -sslserver maven.2xoffice.com*

-----BEGIN CERTIFICATE-----
MIIFNTCCBB2gAwIBAgIHJ73QrVnyJjANBgkqhkiG9w0BAQsFADCBtDELMAkGA1UEBhMCVVMxEDAO
...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIE3jCCA8agAwIBAgICAwEwDQYJKoZIhvcNAQEFBQAwYzELMAkGA1UEBhMCVVMxITAfBgNVBAoT
...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIEADCCAuigAwIBAgIBADANBgkqhkiG9w0BAQUFADBjMQswCQYDVQQGEwJVUzEhMB8GA1UEChMY
...
-----END CERTIFICATE-----
The -rfc option outputs the certificate chain in PEM-encoded format for easy import back into a keystore.

Step 2: Save the whole thing (including the BEGIN CERTIFICATE and END CERTIFICATE lines, which are significant in this case) as godaddyg2.pem and imported it into my trust store via:

Step 3: Import the certificate in the keystore( java trusted key store)

$ keytool -importcert -file ./godaddyg2.pem -keystore $JRE_LIB/lib/security/cacerts

Different ways of adding to Dictionary

Given the, most than probable similarities in performance, use whatever feel more correct and readable to the piece of code you're using.

I feel an operation that describes an addition, being the presence of the key already a really rare exception is best represented with the add. Semantically it makes more sense.

The dict[key] = value represents better a substitution. If I see that code I half expect the key to already be in the dictionary anyway.

SELECT FOR UPDATE with SQL Server

You cannot have snapshot isolation and blocking reads at the same time. The purpose of snapshot isolation is to prevent blocking reads.

How to format code in Xcode?

Select first the text you want to format and then press Ctrl+I.

Use Cmd+A first if you wish to format all text in the selected file.

Note: this procedure only re-indents the lines, it does not do any advanced formatting.


In XCode 12 beta:

The new key binding to re-indent is control+I.

blur vs focusout -- any real differences?

The documentation for focusout says (emphasis mine):

The focusout event is sent to an element when it, or any element inside of it, loses focus. This is distinct from the blur event in that it supports detecting the loss of focus on descendant elements (in other words, it supports event bubbling).

The same distinction exists between the focusin and focus events.

Compare 2 arrays which returns difference

I know this is an old question, but I thought I would share this little trick.

var diff = $(old_array).not(new_array).get();

diff now contains what was in old_array that is not in new_array

MongoDB or CouchDB - fit for production?

I'm the CTO of 10gen (developers of MongoDB) so I'm a bit biased, but I also manage a few sites that are using MongoDB in production.

businessinsider has been using mongo in production for over a year now. They are using it for everything from users and blog posts, to every image on the site.

shopwiki is using it for a few things including real time analytics and a caching layer. They are doing over 1000 writes per second to a fairly large database.

If you go to the mongodb Production Deployments page you'll see some people who are using mongo in production.

If you have any questions about the scale or scope of production deployments, post on our user list and we'll be more than happy to help.

Get year, month or day from numpy datetime64

Anon's answer works great for me, but I just need to modify the statement for days

from:

days = dates - dates.astype('datetime64[M]') + 1

to:

days = dates.astype('datetime64[D]') - dates.astype('datetime64[M]') + 1

How to install Laravel's Artisan?

Use the project's root folder

Artisan comes with Laravel by default, if your php command works fine, then the only thing you need to do is to navigate to the project's root folder. The root folder is the parent folder of the app folder. For example:

cd c:\Program Files\xampp\htdocs\your-project-name

Now the php artisan list command should work fine, because PHP runs the file called artisan in the project's folder.

Install the framework

Keep in mind that Artisan runs scripts stored in the vendor folder, so if you installed Laravel without Composer, like downloading and extracting the Laravel GitHub repo, then you don't have the framework itself and you may get the following error when you try to use Artisan:

Could not open input file: artisan

To solve this you have to install the framework itself by running composer install in your project's root folder.

How to insert special characters into a database?

Use this: htmlentities($_POST['field']);

Enough only. This for special character:

Use for CI htmlentities($this->input->post('control_name'));

Where can I set path to make.exe on Windows?

Why don't you create a bat file makedos.bat containing the following line?

c:\DOS\make.exe %1 %2 %5

and put it in C:\DOS (or C:\Windowsè or make sure that it is in your %path%)

You can run from cmd, SET and it displays all environment variables, including PATH.

In registry you can find environment variables under:

  • HKEY_CURRENT_USER\Environment
  • HKEY_CURRENT_USER\Volatile Environment
  • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Environment

Module not found: Error: Can't resolve 'core-js/es6'

Sure, I had a similar issue and a simple

npm uninstall @babel/polyfill --save &&
npm install @babel/polyfill --save

did the trick for me.

However, usage of @babel/polyfill is deprecated (according to this comment) so only try this if you think you have older packages installed or if all else fails.

Remove scrollbar from iframe

in your css:

iframe{
    overflow:hidden;
}

Run a mySQL query as a cron job?

This was a very handy page as I have a requirement to DELETE records from a mySQL table where the expiry date is < Today.

I am on a shared host and CRON did not like the suggestion AndrewKDay. it also said (and I agree) that exposing the password in this way could be insecure.

I then tried turning Events ON in phpMyAdmin but again being on a shared host this was a no no. Sorry fancyPants.

So I turned to embedding the SQL script in a PHP file. I used the example [here][1]

[1]: https://www.w3schools.com/php/php_mysql_create_table.asp stored it in a sub folder somewhere safe and added an empty index.php for good measure. I was then able to test that this PHP file (and my SQL script) was working from the browser URL line.

All good so far. On to CRON. Following the above example almost worked. I ended up calling PHP before the path for my *.php file. Otherwise CRON didn't know what to do with the file.

my cron is set to run once per day and looks like this, modified for security.

00 * * * * php mywebsiteurl.com/wp-content/themes/ForteChildTheme/php/DeleteExpiredAssessment.php

For the final testing with CRON I initially set it to run each minute and had email alerts turned on. This quickly confirmed that it was running as planned and I changed it back to once per day.

Hope this helps.

How to refresh activity after changing language (Locale) inside application

You can use recreate(); to restart your activity when Language change.

I am using following code to restart activity when language change:

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
Configuration config = getBaseContext().getResources().getConfiguration();

String lang = settings.getString("lang_list", "");

if (! "".equals(lang) && ! config.locale.getLanguage().equals(lang)) {
      recreate();  //this is used for recreate activity
      Locale locale = new Locale(lang);
      Locale.setDefault(locale);
      config.locale = locale;
      getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
}

I keep getting this error for my simple python program: "TypeError: 'float' object cannot be interpreted as an integer"

In:

for i in range(c/10):

You're creating a float as a result - to fix this use the int division operator:

for i in range(c // 10):

Convert Enumeration to a Set/List

If you need Set rather than List, you can use EnumSet.allOf().

Set<EnumerationClass> set = EnumSet.allOf(EnumerationClass.class);

Update: JakeRobb is right. My answer is about java.lang.Enum instead of java.util.Enumeration. Sorry for unrelated answer.

How to do logging in React Native?

console.log() is the easy way to debug your code but it need to be use with arrow function or bind() while displaying any state. You may find the link useful.

What is jQuery Unobtrusive Validation?

With the unobtrusive way:

  • You don't have to call the validate() method.
  • You specify requirements using data attributes (data-val, data-val-required, etc.)

Jquery Validate Example:

<input type="text" name="email" class="required">
<script>
        $(function () {
            $("form").validate();
        });
</script>

Jquery Validate Unobtrusive Example:

<input type="text" name="email" data-val="true" 
data-val-required="This field is required.">  

<div class="validation-summary-valid" data-valmsg-summary="true">
    <ul><li style="display:none"></li></ul>
</div>

What is a stack pointer used for in microprocessors?

A stack pointer is a small register that stores the address of the top of stack. It is used for the purpose of pointing address of the top of the stack.

Vue is not defined

Sometimes the problem may be if you import that like this:

const Vue = window.vue;

this may overwrite the original Vue reference.

Java: Best way to iterate through a Collection (here ArrayList)

All of them have there own uses:

  1. If you have an iterable and need to traverse unconditionally to all of them:

    for (iterable_type iterable_element : collection)

  2. If you have an iterable but need to conditionally traverse:

    for (Iterator iterator = collection.iterator(); iterator.hasNext();)

  3. If data-structure does not implement iterable:

    for (int i = 0; i < collection.length; i++)

Android: Clear Activity Stack

Intent intent = new Intent(LoginActivity.this,MainActivity.class); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); startActivity(intent); finish();

Setting Margin Properties in code

It's a bit unclear what are you asking, but to make things comfortable, you can inherit your own Control and add a property with the code that Marc suggests:

class MyImage : Image {
    private Thickness thickness;
    public double MarginLeft {
        get { return Margin.Left; }
        set { thickness = Margin; thickness.Left = value; Margin = thickness; }
    }
}

Then in the client code you can write just

MyImage img = new MyImage();
img.MarginLeft = 10;
MessageBox.Show(img.Margin.Left.ToString()); // or img.MarginLeft

How to get the class of the clicked element?

Here's a quick jQuery example that adds a click event to each "li" tag, and then retrieves the class attribute for the clicked element. Hope it helps.

$("li").click(function() {
   var myClass = $(this).attr("class");
   alert(myClass);
});

Equally, you don't have to wrap the object in jQuery:

$("li").click(function() {
   var myClass = this.className;
   alert(myClass);
});

And in newer browsers you can get the full list of class names:

$("li").click(function() {
   var myClasses = this.classList;
   alert(myClasses.length + " " + myClasses[0]);
});

You can emulate classList in older browsers using myClass.split(/\s+/);

Instagram API - How can I retrieve the list of people a user is following on Instagram

The REST API of Instagram has been discontinued. But you can use GraphQL to get the desired data. Here you can find an overview: https://developers.facebook.com/docs/instagram-api

How to edit the size of the submit button on a form?

<input type="button" value="submit" style="height: 100px; width: 100px; left: 250; top: 250;">

Use this with your requirements.

Python: most idiomatic way to convert None to empty string?

def xstr(s):
    return '' if s is None else str(s)

Format a JavaScript string using placeholders and an object of substitutions?

If you want to do something closer to console.log like replacing %s placeholders like in

>console.log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright")
>Hello Loreto how are you today is everything allright?

I wrote this

_x000D_
_x000D_
function log() {_x000D_
  var args = Array.prototype.slice.call(arguments);_x000D_
  var rep= args.slice(1, args.length);_x000D_
  var i=0;_x000D_
  var output = args[0].replace(/%s/g, function(match,idx) {_x000D_
    var subst=rep.slice(i, ++i);_x000D_
    return( subst );_x000D_
  });_x000D_
   return(output);_x000D_
}_x000D_
res=log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright");_x000D_
document.getElementById("console").innerHTML=res;
_x000D_
<span id="console"/>
_x000D_
_x000D_
_x000D_

you will get

>log("Hello %s how are you %s is everything %s?", "Loreto", "today", "allright")
>"Hello Loreto how are you today is everything allright?"

UPDATE

I have added a simple variant as String.prototype useful when dealing with string transformations, here is it:

String.prototype.log = function() {
    var args = Array.prototype.slice.call(arguments);
    var rep= args.slice(0, args.length);
    var i=0;
    var output = this.replace(/%s|%d|%f|%@/g, function(match,idx) {
      var subst=rep.slice(i, ++i);
      return( subst );
    });
    return output;
   }

In that case you will do

"Hello %s how are you %s is everything %s?".log("Loreto", "today", "allright")
"Hello Loreto how are you today is everything allright?"

Try this version here

How to get file extension from string in C++

Good answers but I see most of them has some problems: First of all I think a good answer should work for complete file names which have their path headings, also it should work for linux or windows or as mentioned it should be cross platform. For most of answers; file names with no extension but a path with a folder name including dot, the function will fail to return the correct extension: examples of some test cases could be as follow:

    const char filename1 = {"C:\\init.d\\doc"}; // => No extention
    const char filename2 = {"..\\doc"}; //relative path name => No extention
    const char filename3 = {""}; //emputy file name => No extention
    const char filename4 = {"testing"}; //only single name => No extention
    const char filename5 = {"tested/k.doc"}; // normal file name => doc
    const char filename6 = {".."}; // parent folder => No extention
    const char filename7 = {"/"}; // linux root => No extention
    const char filename8 = {"/bin/test.d.config/lx.wize.str"}; // ordinary path! => str

"brian newman" suggestion will fail for filename1 and filename4. and most of other answers which are based on reverse find will fail for filename1. I suggest including the following method in your source: which is function returning index of first character of extension or the length of given string if not found.

size_t find_ext_idx(const char* fileName)
{
    size_t len = strlen(fileName);
    size_t idx = len-1;
    for(size_t i = 0; *(fileName+i); i++) {
        if (*(fileName+i) == '.') {
            idx = i;
        } else if (*(fileName + i) == '/' || *(fileName + i) == '\\') {
            idx = len - 1;
        }
    }
    return idx+1;
}

you could use the above code in your c++ application like below:

std::string get_file_ext(const char* fileName)
{
    return std::string(fileName).substr(find_ext_idx(fileName));
}

The last point in some cases the a folder is given to file name as argument and includes a dot in the folder name the function will return folder's dot trailing so better first to user check that the given name is a filename and not folder name.

What languages are Windows, Mac OS X and Linux written in?

Linux: C. Some parts in assembly.

[...] It's mostly in C, but most people wouldn't call what I write C. It uses every conceivable feature of the 386 I could find, as it was also a project to teach me about the 386. As already mentioned, it uses a MMU, for both paging (not to disk yet) and segmentation. It's the segmentation that makes it REALLY 386 dependent (every task has a 64Mb segment for code & data - max 64 tasks in 4Gb. Anybody who needs more than 64Mb/task - tough cookies). [...] Some of my "C"-files (specifically mm.c) are almost as much assembler as C. [...] Unlike minix, I also happen to LIKE interrupts, so interrupts are handled without trying to hide the reason behind them. (Source)

Mac OS X: Cocoa mostly in Objective-C. Kernel written in C, some parts in assembly.

Mac OS X, at the kernel layer, is mostly an older, free operating system called BSD (specifically, it’s Darwin, a sort of hybrid of BSD, Mach, and a few other things)... almost entirely C, with a bit of assembler thrown in. (Source)

Much of Cocoa is implemented in Objective-C, an object-oriented language that is compiled to run at incredible speed, yet employes a truly dynamic runtime making it uniquely flexible. Because Objective-C is a superset of C, it is easy to mix C and even C++ into your Cocoa applications. (Source)

Windows: C, C++, C#. Some parts in assembler.

We use almost entirely C, C++, and C# for Windows. Some areas of code are hand tuned/hand written assembly. (Source)

Unix: C. Some parts in assembly. (Source)

Extract time from date String

Use SimpleDateFormat to convert between a date string and a real Date object. with a Date as starting point, you can easily apply formatting based on various patterns as definied in the javadoc of the SimpleDateFormat (click the blue code link for the Javadoc).

Here's a kickoff example:

String originalString = "2010-07-14 09:00:02";
Date date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(originalString);
String newString = new SimpleDateFormat("H:mm").format(date); // 9:00

Multiple try codes in one block

You can use fuckit module.
Wrap your code in a function with @fuckit decorator:

@fuckit
def func():
    code a
    code b #if b fails, it should ignore, and go to c.
    code c #if c fails, go to d
    code d

Launching an application (.EXE) from C#?

If you have problems using System.Diagnostics like I had, use the following simple code that will work without it:

using System.Diagnostics;

Process notePad = new Process();
notePad.StartInfo.FileName   = "notepad.exe";
notePad.StartInfo.Arguments = "mytextfile.txt";
notePad.Start();

The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly

I was actually searching for a similar error and Google sent me here to this question. The error was:

The type arguments for method 'IModelExpressionProvider.CreateModelExpression(ViewDataDictionary, Expression>)' cannot be inferred from the usage

I spent maybe 15 minutes trying to figure it out. It was happening inside a Razor .cshtml view file. I had to comment portions of the view code to get to where it was barking since the compiler didn't help much.

<div class="form-group col-2">
    <label asp-for="Organization.Zip"></label>
    <input asp-for="Organization.Zip" class="form-control">
    <span asp-validation-for="Zip" class="color-type-alert"></span>
</div>

Can you spot it? Yeah... I re-checked it maybe twice and didn't get it at first!

See that the ViewModel's property is just Zip when it should be Organization.Zip. That was it.

So re-check your view source code... :-)

javascript windows alert with redirect function

Alert will block the program flow so you can just write the following.

echo ("<script LANGUAGE='JavaScript'>
    window.alert('Succesfully Updated');
    window.location.href='http://someplace.com';
    </script>");

How do I limit the number of decimals printed for a double?

Check out DecimalFormat: http://docs.oracle.com/javase/6/docs/api/java/text/DecimalFormat.html

You'll do something like:

new DecimalFormat("$#.00").format(shippingCost);

Or since you're working with currency, you could see how NumberFormat.getCurrencyInstance() works for you.

Replace specific characters within strings

You do not need to create data frame from vector of strings, if you want to replace some characters in it. Regular expressions is good choice for it as it has been already mentioned by @Andrie and @Dirk Eddelbuettel.

Pay attention, if you want to replace special characters, like dots, you should employ full regular expression syntax, as shown in example below:

ctr_names <- c("Czech.Republic","New.Zealand","Great.Britain")
gsub("[.]", " ", ctr_names)

this will produce

[1] "Czech Republic" "New Zealand"    "Great Britain" 

Can a Windows batch file determine its own file name?

Below is my initial code:

@echo off
Set z=%%
echo.
echo %z%0.......%0
echo %z%~0......%~0
echo %z%n0......%n0
echo %z%x0......%x0
echo %z%~n0.....%~n0
echo %z%dp0.....%dp0
echo %z%~dp0....%~dp0
echo.

I noticed that file name given by %~0 and %0 is the way it was entered in the command-shell and not how that file is actually named. So if you want the literal case used for the file name you should use %~n0. However, this will leave out the file extension. But if you know the file name you could add the following code.

set b=%~0
echo %~n0%b:~8,4%

I have learned that ":~8,4%" means start at the 9th character of the variable and then show show the next 4 characters. The range is 0 to the end of the variable string. So %Path% would be very long!

fIlEnAmE.bat
012345678901

However, this is not as sound as Jool's solution (%~x0) above.

My Evidence:

C:\bin>filename.bat

%0.......filename.bat
%~0......filename.bat
. . .

C:\bin>fIlEnAmE.bat

%0.......fIlEnAmE.bat
%~0......fIlEnAmE.bat
%n0......n0
%x0......x0
%~n0.....FileName
%dp0.....dp0
%~dp0....C:\bin\

%~n0%b:~8,4%...FileName.bat

Press any key to continue . . .

C:\bin>dir
 Volume in drive C has no label.
 Volume Serial Number is CE18-5BD0

 Directory of C:\bin
. . .
05/02/2018  11:22 PM               208 FileName.bat

Here is the final code

@echo off
Set z=%%
set b=%~0
echo.
echo %z%0.......%0
echo %z%~0......%~0
echo %z%n0......%n0
echo %z%x0......%x0
echo %z%~n0.....%~n0
echo %z%dp0.....%dp0
echo %z%~dp0....%~dp0
echo.
echo A complex solution:
echo ===================================
echo %z%~n0%z%b:~8,4%z%...%~n0%b:~8,4%
echo ===================================
echo.
echo The preferred solution:
echo ===================================
echo %z%~n0%z%~x0.......%~n0%~x0
echo ===================================
pause

Java - Reading XML file

Avoid hardcoding try making the code that is dynamic below is the code it will work for any xml I have used SAX Parser you can use dom,xpath it's upto you I am storing all the tags name and values in the map after that it becomes easy to retrieve any values you want I hope this helps
SAMPLE XML:

<parent>
<child >
    <child1> value 1 </child1>
    <child2> value 2 </child2>
    <child3> value 3 </child3>
    </child>
    <child >
     <child4> value 4 </child4>
    <child5> value 5</child5>
    <child6> value 6 </child6>
    </child>
  </parent>

JAVA CODE:

 import java.io.File;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.LinkedHashMap;
    import java.util.Map;
    import javax.xml.parsers.ParserConfigurationException;
    import javax.xml.parsers.SAXParser;
    import javax.xml.parsers.SAXParserFactory;
    import org.xml.sax.Attributes;
    import org.xml.sax.SAXException;
    import org.xml.sax.helpers.DefaultHandler;


    public class saxParser {
           static Map<String,String> tmpAtrb=null;
           static Map<String,String> xmlVal= new LinkedHashMap<String, String>();
        public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, VerifyError {

            /**
             * We can pass the class name of the XML parser
             * to the SAXParserFactory.newInstance().
             */

            //SAXParserFactory saxDoc = SAXParserFactory.newInstance("com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl", null);

            SAXParserFactory saxDoc = SAXParserFactory.newInstance();
            SAXParser saxParser = saxDoc.newSAXParser();

            DefaultHandler handler = new DefaultHandler() {
                String tmpElementName = null;
                String tmpElementValue = null;


                @Override
                public void startElement(String uri, String localName, String qName, 
                                                                    Attributes attributes) throws SAXException {
                    tmpElementValue = "";
                    tmpElementName = qName;
                    tmpAtrb=new HashMap();
                    //System.out.println("Start Element :" + qName);
                    /**
                     * Store attributes in HashMap
                     */
                    for (int i=0; i<attributes.getLength(); i++) {
                        String aname = attributes.getLocalName(i);
                        String value = attributes.getValue(i);
                        tmpAtrb.put(aname, value);
                    }

                }

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

                    if(tmpElementName.equals(qName)){
                        System.out.println("Element Name :"+tmpElementName);
                    /**
                     * Retrive attributes from HashMap
                     */                    for (Map.Entry<String, String> entrySet : tmpAtrb.entrySet()) {
                            System.out.println("Attribute Name :"+ entrySet.getKey() + "Attribute Value :"+ entrySet.getValue());
                        }
                        System.out.println("Element Value :"+tmpElementValue);
                        xmlVal.put(tmpElementName, tmpElementValue);
                        System.out.println(xmlVal);
                      //Fetching The Values From The Map
                        String getKeyValues=xmlVal.get(tmpElementName);
                        System.out.println("XmlTag:"+tmpElementName+":::::"+"ValueFetchedFromTheMap:"+getKeyValues);   
                    }   
                }
                @Override
                public void characters(char ch[], int start, int length) throws SAXException {
                    tmpElementValue = new String(ch, start, length) ;  
                } 
            };
            /**
             * Below two line used if we use SAX 2.0
             * Then last line not needed.
             */

            //saxParser.setContentHandler(handler);
            //saxParser.parse(new InputSource("c:/file.xml"));
            saxParser.parse(new File("D:/Test _ XML/file.xml"), handler);
        }  
    }

OUTPUT:

Element Name :child1
Element Value : value 1 
XmlTag:<child1>:::::ValueFetchedFromTheMap: value 1 
Element Name :child2
Element Value : value 2 
XmlTag:<child2>:::::ValueFetchedFromTheMap: value 2 
Element Name :child3
Element Value : value 3 
XmlTag:<child3>:::::ValueFetchedFromTheMap: value 3 
Element Name :child4
Element Value : value 4 
XmlTag:<child4>:::::ValueFetchedFromTheMap: value 4 
Element Name :child5
Element Value : value 5
XmlTag:<child5>:::::ValueFetchedFromTheMap: value 5
Element Name :child6
Element Value : value 6 
XmlTag:<child6>:::::ValueFetchedFromTheMap: value 6 
Values Inside The Map:{child1= value 1 , child2= value 2 , child3= value 3 , child4= value 4 , child5= value 5, child6= value 6 }

CSS div 100% height

CSS Flexbox was designed to simplify creating these types of layouts.

_x000D_
_x000D_
html {
  height: 100%;
}

body {
  height: 100%;
  display: flex;
}

.Content {
  flex-grow: 1;
}

.Sidebar {
  width: 290px;
  flex-shrink: 0;
}
_x000D_
<div class="Content" style="background:#bed">Content</div>
<div class="Sidebar" style="background:#8cc">Sidebar</div>
_x000D_
_x000D_
_x000D_

Parse an HTML string with JS

The fastest way to parse HTML in Chrome and Firefox is Range#createContextualFragment:

var range = document.createRange();
range.selectNode(document.body); // required in Safari
var fragment = range.createContextualFragment('<h1>html...</h1>');
var firstNode = fragment.firstChild;

I would recommend to create a helper function which uses createContextualFragment if available and falls back to innerHTML otherwise.

Benchmark: http://jsperf.com/domparser-vs-createelement-innerhtml/3

How do you set the document title in React?

the easiest way is to use react-document-configuration

npm install react-document-configuration --save

Example:

import React from "react";
import Head from "react-document-configuration";

export default function Application() {
    return (
        <div>
            <Head title="HOME" icon="link_of_icon" />
            <div>
                <h4>Hello Developers!</h4>
            </div>
        </div>
    );
};```

Script Tag - async & defer

It seems the behavior of defer and async is browser dependent, at least on the execution phase. NOTE, defer only applies to external scripts. I'm assuming async follows same pattern.

In IE 11 and below, the order seems to be like this:

  • async (could partially execute while page loading)
  • none (could execute while page loading)
  • defer (executes after page loaded, all defer in order of placement in file)

In Edge, Webkit, etc, the async attribute seems to be either ignored or placed at the end:

  • data-pagespeed-no-defer (executes before any other scripts, while page is loading)
  • none (could execute while page is loading)
  • defer (waits until DOM loaded, all defer in order of placement in file)
  • async (seems to wait until DOM loaded)

In newer browsers, the data-pagespeed-no-defer attribute runs before any other external scripts. This is for scripts that don't depend on the DOM.

NOTE: Use defer when you need an explicit order of execution of your external scripts. This tells the browser to execute all deferred scripts in order of placement in the file.

ASIDE: The size of the external javascripts did matter when loading...but had no effect on the order of execution.

If you're worried about the performance of your scripts, you may want to consider minification or simply loading them dynamically with an XMLHttpRequest.

Unique constraint on multiple columns

This can also be done in the GUI. Here's an example adding a multi-column unique constraint to an existing table.

  1. Under the table, right click Indexes->Click/hover New Index->Click Non-Clustered Index...

enter image description here

  1. A default Index name will be given but you may want to change it. Check the Unique checkbox and click Add... button

enter image description here

  1. Check the columns you want included

enter image description here

Click OK in each window and you're done.

How can I search an array in VB.NET?

Dim inputString As String = "ra"
Enumerable.Range(0, arr.Length).Where(Function(x) arr(x).ToLower().Contains(inputString.ToLower()))

C# Error: Parent does not contain a constructor that takes 0 arguments

You need to change the constructor of the child class to this:

public child(int i) : base(i)
{
    Console.WriteLine("child");
}

The part : base(i) means that the constructor of the base class with one int parameter should be used. If this is missing, you are implicitly telling the compiler to use the default constructor without parameters. Because no such constructor exists in the base class it is giving you this error.

Error when trying vagrant up

Follow the below syntax when creating the virtual box:

 $ vagrant box add {title} {url}
 $ vagrant init {title}
 $ vagrant up

See http://www.vagrantbox.es/

How to search a Git repository by commit message?

first to list the commits use

git log --oneline

then find the SHA of the commit (Message), then I used

 git log --stat 8zad24d

(8zad24d) is the SHA assosiated with the commit you are intrested in (the first couples sha example (8zad24d) you can select 4 char or 6 or 8 or the entire sha) to find the right info

Converting RGB to grayscale/intensity

What is the source of these values?

The "source" of the coefficients posted are the NTSC specifications which can be seen in Rec601 and Characteristics of Television.

The "ultimate source" are the CIE circa 1931 experiments on human color perception. The spectral response of human vision is not uniform. Experiments led to weighting of tristimulus values based on perception. Our L, M, and S cones1 are sensitive to the light wavelengths we identify as "Red", "Green", and "Blue" (respectively), which is where the tristimulus primary colors are derived.2

The linear light3 spectral weightings for sRGB (and Rec709) are:

Rlin * 0.2126 + Glin * 0.7152 + Blin * 0.0722 = Y

These are specific to the sRGB and Rec709 colorspaces, which are intended to represent computer monitors (sRGB) or HDTV monitors (Rec709), and are detailed in the ITU documents for Rec709 and also BT.2380-2 (10/2018)

FOOTNOTES (1) Cones are the color detecting cells of the eye's retina.
(2) However, the chosen tristimulus wavelengths are NOT at the "peak" of each cone type - instead tristimulus values are chosen such that they stimulate on particular cone type substantially more than another, i.e. separation of stimulus.
(3) You need to linearize your sRGB values before applying the coefficients. I discuss this in another answer here.

How to get the Parent's parent directory in Powershell?

You can use

(get-item $scriptPath).Directoryname

to get the string path or if you want the Directory type use:

(get-item $scriptPath).Directory

How to prevent scanf causing a buffer overflow in C?

It's not that much work to make a function that's allocating the needed memory for your string. That's a little c-function i wrote some time ago, i always use it to read in strings.

It will return the read string or if a memory error occurs NULL. But be aware that you have to free() your string and always check for it's return value.

#define BUFFER 32

char *readString()
{
    char *str = malloc(sizeof(char) * BUFFER), *err;
    int pos;
    for(pos = 0; str != NULL && (str[pos] = getchar()) != '\n'; pos++)
    {
        if(pos % BUFFER == BUFFER - 1)
        {
            if((err = realloc(str, sizeof(char) * (BUFFER + pos + 1))) == NULL)
                free(str);
            str = err;
        }
    }
    if(str != NULL)
        str[pos] = '\0';
    return str;
}

Set Icon Image in Java

Your problem is often due to looking in the wrong place for the image, or if your classes and images are in a jar file, then looking for files where files don't exist. I suggest that you use resources to get rid of the second problem.

e.g.,

// the path must be relative to your *class* files
String imagePath = "res/Image.png";
InputStream imgStream = Game.class.getResourceAsStream(imagePath );
BufferedImage myImg = ImageIO.read(imgStream);
// ImageIcon icon = new ImageIcon(myImg);

// use icon here
game.frame.setIconImage(myImg);

Error while trying to run project: Unable to start program. Cannot find the file specified

I just re-ran into the same issue: Console App, Visual Studio 2013, 64 bit OS. The project's settings was set to "Any CPU", I created a new configuration for x86 and VS was happy.

  • In Your Solution Explorer, Right Click your solution (.sln), choose "Configuration Manager"
  • Active Solution Platform: If it's saying "Any CPU", click the drop down arrow and choose ""
  • In the "Type or select the new platform", enter "x86"
  • Now, make sure that the "Active solution platform" is set to x86
  • Run (F5)

How to parse XML and count instances of a particular node attribute?

If you don't want to use any external libraries or 3rd party tools, Please try below code.

  • This will parse xml into python dictionary
  • This will parse xml attrbutes as well
  • This will also parse empty tags like <tag/> and tags with only attributes like <tag var=val/>

Code

import re

def getdict(content):
    res=re.findall("<(?P<var>\S*)(?P<attr>[^/>]*)(?:(?:>(?P<val>.*?)</(?P=var)>)|(?:/>))",content)
    if len(res)>=1:
        attreg="(?P<avr>\S+?)(?:(?:=(?P<quote>['\"])(?P<avl>.*?)(?P=quote))|(?:=(?P<avl1>.*?)(?:\s|$))|(?P<avl2>[\s]+)|$)"
        if len(res)>1:
            return [{i[0]:[{"@attributes":[{j[0]:(j[2] or j[3] or j[4])} for j in re.findall(attreg,i[1].strip())]},{"$values":getdict(i[2])}]} for i in res]
        else:
            return {res[0]:[{"@attributes":[{j[0]:(j[2] or j[3] or j[4])} for j in re.findall(attreg,res[1].strip())]},{"$values":getdict(res[2])}]}
    else:
        return content

with open("test.xml","r") as f:
    print(getdict(f.read().replace('\n','')))

Sample input

<details class="4b" count=1 boy>
    <name type="firstname">John</name>
    <age>13</age>
    <hobby>Coin collection</hobby>
    <hobby>Stamp collection</hobby>
    <address>
        <country>USA</country>
        <state>CA</state>
    </address>
</details>
<details empty="True"/>
<details/>
<details class="4a" count=2 girl>
    <name type="firstname">Samantha</name>
    <age>13</age>
    <hobby>Fishing</hobby>
    <hobby>Chess</hobby>
    <address current="no">
        <country>Australia</country>
        <state>NSW</state>
    </address>
</details>

Output (Beautified)

[
  {
    "details": [
      {
        "@attributes": [
          {
            "class": "4b"
          },
          {
            "count": "1"
          },
          {
            "boy": ""
          }
        ]
      },
      {
        "$values": [
          {
            "name": [
              {
                "@attributes": [
                  {
                    "type": "firstname"
                  }
                ]
              },
              {
                "$values": "John"
              }
            ]
          },
          {
            "age": [
              {
                "@attributes": []
              },
              {
                "$values": "13"
              }
            ]
          },
          {
            "hobby": [
              {
                "@attributes": []
              },
              {
                "$values": "Coin collection"
              }
            ]
          },
          {
            "hobby": [
              {
                "@attributes": []
              },
              {
                "$values": "Stamp collection"
              }
            ]
          },
          {
            "address": [
              {
                "@attributes": []
              },
              {
                "$values": [
                  {
                    "country": [
                      {
                        "@attributes": []
                      },
                      {
                        "$values": "USA"
                      }
                    ]
                  },
                  {
                    "state": [
                      {
                        "@attributes": []
                      },
                      {
                        "$values": "CA"
                      }
                    ]
                  }
                ]
              }
            ]
          }
        ]
      }
    ]
  },
  {
    "details": [
      {
        "@attributes": [
          {
            "empty": "True"
          }
        ]
      },
      {
        "$values": ""
      }
    ]
  },
  {
    "details": [
      {
        "@attributes": []
      },
      {
        "$values": ""
      }
    ]
  },
  {
    "details": [
      {
        "@attributes": [
          {
            "class": "4a"
          },
          {
            "count": "2"
          },
          {
            "girl": ""
          }
        ]
      },
      {
        "$values": [
          {
            "name": [
              {
                "@attributes": [
                  {
                    "type": "firstname"
                  }
                ]
              },
              {
                "$values": "Samantha"
              }
            ]
          },
          {
            "age": [
              {
                "@attributes": []
              },
              {
                "$values": "13"
              }
            ]
          },
          {
            "hobby": [
              {
                "@attributes": []
              },
              {
                "$values": "Fishing"
              }
            ]
          },
          {
            "hobby": [
              {
                "@attributes": []
              },
              {
                "$values": "Chess"
              }
            ]
          },
          {
            "address": [
              {
                "@attributes": [
                  {
                    "current": "no"
                  }
                ]
              },
              {
                "$values": [
                  {
                    "country": [
                      {
                        "@attributes": []
                      },
                      {
                        "$values": "Australia"
                      }
                    ]
                  },
                  {
                    "state": [
                      {
                        "@attributes": []
                      },
                      {
                        "$values": "NSW"
                      }
                    ]
                  }
                ]
              }
            ]
          }
        ]
      }
    ]
  }
]

How to reset the state of a Redux store?

I've created a component to give Redux the ability of resetting state, you just need to use this component to enhance your store and dispatch a specific action.type to trigger reset. The thought of implementation is same as what @Dan Abramov said.

Github: https://github.com/wwayne/redux-reset

Namespace for [DataContract]

First, I add the references to my Model, then I use them in my code. There are two references you should add:

using System.ServiceModel;
using System.Runtime.Serialization;

then, this problem was solved in my program. I hope this answer can help you. Thanks.

Can you force Visual Studio to always run as an Administrator in Windows 8?

NOTE in recent VS versions (2015+) it seems this extension no longer exists/has this feature.


You can also download VSCommands for VS2012 by Squared Infinity which has a feature to change it to run as admin (as well as some other cool bits and pieces)

enter image description here

Update

One can install the commands from the Visual Studio menu bar using Tools->Extensions and Updates selecting Online and searching for vscommands where then one selects VSCommands for Visual Studio 20XX depending on whether using 2012 or 2013 (or greater going forward) and download and install.

MS Access: how to compact current database in VBA

If you want to compact/repair an external mdb file (not the one you are working in just now):

Application.compactRepair sourecFile, destinationFile

If you want to compact the database you are working with:

Application.SetOption "Auto compact", True

In this last case, your app will be compacted when closing the file.

My opinion: writting a few lines of code in an extra MDB "compacter" file that you can call when you want to compact/repair an mdb file is very usefull: in most situations the file that needs to be compacted cannot be opened normally anymore, so you need to call the method from outside the file.

Otherwise, the autocompact shall by default be set to true in each main module of an Access app.

In case of a disaster, create a new mdb file and import all objects from the buggy file. You will usually find a faulty object (form, module, etc) that you will not be able to import.

How to use moment.js library in angular 2 typescript app?

For ANGULAR CLI users

Using external libraries is in the documentation here:

https://github.com/angular/angular-cli/wiki/stories-third-party-lib

Simply install your library via

npm install lib-name --save

and import it in your code. If the library does not include typings, you can install them using:

npm install lib-name --save

npm install @types/lib-name --save-dev

Then open src/tsconfig.app.json and add it to the types array:

"types":[ "lib-name" ]

If the library you added typings for is only to be used on your e2e tests, instead use e2e/tsconfig.e2e.json. The same goes for unit tests and src/tsconfig.spec.json.

If the library doesn't have typings available at @types/, you can still use it by manually adding typings for it:

First, create a typings.d.ts file in your src/ folder.

This file will be automatically included as global type definition. Then, in src/typings.d.ts, add the following code:

declare module 'typeless-package';

Finally, in the component or file that uses the library, add the following code:

import * as typelessPackage from 'typeless-package'; typelessPackage.method();

Done. Note: you might need or find useful to define more typings for the library that you're trying to use.

Where does npm install packages?

I was beginning to go mad while searching for the real configuration, so here is the list of all configuration files on linux:

  • /etc/npmrc
  • /home/youruser/.npmrc
  • /root/.npmrc
  • ./.npmrc in the current directory next to package.json file (thanks to @CyrillePontvieux)

on windows:

  • c/Program\ Files/nodejs/node_modules/npm/npmrc

Then in this file the prefix is configured:

prefix=/usr

The prefix is defaulted to /usr in linux, to ${APPDATA}\npm in windows

The node modules are under $prefix tree, and the path should contain $prefix/bin

There may be a problem :

  • When you install globally, you use "sudo su" then the /root/.npmrc may be used!
  • When you use locally without sudo: for your user its the /home/youruser/.npmrc.
  • When your path doesn't represent your prefix
  • When you use npm set -g prefix /usr it sets the /etc/npmrc global, but doesn't override the local

Here is all the informations that were missing to find what is configured where. Hope I have been exhaustive.

How do I get a list of installed CPAN modules?

As you enter your Perl script you have all the installed modules as .pm files below the folders in @INC so a small bash script will do the job for you:

#!/bin/bash

echo -e -n "Content-type: text/plain\n\n"

inc=`perl -e '$, = "\n"; print @INC;'`

for d in $inc
do
   find $d -name '*.pm'
done

Multiple selector chaining in jQuery?

I think you might see slightly better performance by doing it this way:

$("#Create, #Edit").find(".myClass").plugin(){
    // Options
});

How can I set Image source with base64

Your problem are the cr (carriage return)

http://jsfiddle.net/NT9KB/210/

you can use:

document.getElementById("img").src = "data:image/png;base64, iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="

How to set some xlim and ylim in Seaborn lmplot facetgrid

The lmplot function returns a FacetGrid instance. This object has a method called set, to which you can pass key=value pairs and they will be set on each Axes object in the grid.

Secondly, you can set only one side of an Axes limit in matplotlib by passing None for the value you want to remain as the default.

Putting these together, we have:

g = sns.lmplot('X', 'Y', df, col='Z', sharex=False, sharey=False)
g.set(ylim=(0, None))

enter image description here

PostgreSQL delete all content

For small tables DELETE is often faster and needs less aggressive locking (for heavy concurrent load):

DELETE FROM tbl;

With no WHERE condition.

For medium or bigger tables, go with TRUNCATE tbl, like @Greg posted.

Class extending more than one class Java?

No it is not possible in java (Maybe in java 8 it will be avilable). Except the case when you extend in a tree. For example:

class A
class B extends A
class C extends B

Google API for location, based on user IP address

Google already appends location data to all requests coming into GAE (see Request Header documentation for go, java, php and python). You should be interested X-AppEngine-Country, X-AppEngine-Region, X-AppEngine-City and X-AppEngine-CityLatLong headers.

An example looks like this:

X-AppEngine-Country:US
X-AppEngine-Region:ca
X-AppEngine-City:norwalk
X-AppEngine-CityLatLong:33.902237,-118.081733

How do I escape a percentage sign in T-SQL?

In MySQL,

WHERE column_name LIKE '%|%%' ESCAPE '|'

System.currentTimeMillis() vs. new Date() vs. Calendar.getInstance().getTime()

System.currentTimeMillis() is obviously the most efficient since it does not even create an object, but new Date() is really just a thin wrapper about a long, so it is not far behind. Calendar, on the other hand, is relatively slow and very complex, since it has to deal with the considerably complexity and all the oddities that are inherent to dates and times (leap years, daylight savings, timezones, etc.).

It's generally a good idea to deal only with long timestamps or Date objects within your application, and only use Calendar when you actually need to perform date/time calculations, or to format dates for displaying them to the user. If you have to do a lot of this, using Joda Time is probably a good idea, for the cleaner interface and better performance.

How to find char in string and get all the indexes?

def find_idx(str, ch):
    yield [i for i, c in enumerate(str) if c == ch]

for idx in find_idx('babak karchini is a beginner in python ', 'i'):
    print(idx)

output:

[11, 13, 15, 23, 29]

Usage of __slots__?

You have — essentially — no use for __slots__.

For the time when you think you might need __slots__, you actually want to use Lightweight or Flyweight design patterns. These are cases when you no longer want to use purely Python objects. Instead, you want a Python object-like wrapper around an array, struct, or numpy array.

class Flyweight(object):

    def get(self, theData, index):
        return theData[index]

    def set(self, theData, index, value):
        theData[index]= value

The class-like wrapper has no attributes — it just provides methods that act on the underlying data. The methods can be reduced to class methods. Indeed, it could be reduced to just functions operating on the underlying array of data.

Python: Passing variables between functions

passing variable from one function as argument to other functions can be done like this

define functions like this

def function1():
global a
a=input("Enter any number\t")

def function2(argument):
print ("this is the entered number - ",argument)

call the functions like this

function1()
function2(a)

Could not open a connection to your authentication agent

Let me offer another solution. If you have just installed Git 1.8.2.2 or thereabouts, and you want to enable SSH, follow the well-writen directions.

Everything through to Step 5.6 where you might encounter a slight snag. If an SSH agent is already be running you could get the following error message when you restart bash

Could not open a connection to your authentication agent

If you do, use the following command to see if more than one ssh-agent process is running

ps aux | grep ssh

If you see more than one ssh-agent service, you will need to kill all of these processes. Use the kill command as follows (the PID will be unique on your computer)

kill <PID>

Example:

kill 1074

After you have removed all of the ssh-agent processes, run the px aux | grep ssh command again to be sure they are gone, then restart Bash.

Voila, you should now get something like this:

Initializing new SSH agent...
succeeded
Enter passphrase for /c/Users/username/.ssh/id_rsa:

Now you can continue on Step 5.7 and beyond.

multiple prints on the same line in Python

Use sys.stdout.write('Installing XXX... ') and sys.stdout.write('Done'). In this way, you have to add the new line by hand with "\n" if you want to recreate the print functionality. I think that it might be unnecessary to use curses just for this.

how to change onclick event with jquery?

(2019) I used $('#'+id).removeAttr().off('click').on('click', function(){...});

I tried $('#'+id).off().on(...), but it wouldn't work to reset the onClick attribute every time it was called to be reset.

I use .on('click',function(){...}); to stay away from having to quote block all my javascript functions.

The O.P. could now use:

$(this).removeAttr('onclick').off('click').on('click', function(){ displayCalendar(document.prjectFrm[ia + 'dtSubDate'],'yyyy-mm-dd', this); });

Where this came through for me is when my div was set with the onClick attribute set statically:

<div onclick = '...'>

Otherwise, if I only had a dynamically attached a listener to it, I would have used the $('#'+id).off().on('click', function(){...});.

Without the off('click') my onClick listeners were being appended not replaced.

How do you Sort a DataTable given column and direction?

In case you want to sort in more than one direction

  public static void sortOutputTable(ref DataTable output)
        {
            DataView dv = output.DefaultView;
            dv.Sort = "specialCode ASC, otherCode DESC";
            DataTable sortedDT = dv.ToTable();
            output = sortedDT;
        }

How to map a composite key with JPA and Hibernate?

Looks like you are doing this from scratch. Try using available reverse engineering tools like Netbeans Entities from Database to at least get the basics automated (like embedded ids). This can become a huge headache if you have many tables. I suggest avoid reinventing the wheel and use as many tools available as possible to reduce coding to the minimum and most important part, what you intent to do.

jQuery move to anchor location on page load

Put this right before the closing Body tag at the bottom of the page.

<script>
    if (location.hash) {
        location.href = location.hash;
    }
</script>

jQuery is actually not required.

Present and dismiss modal view controller

First of all, when you put that code in applicationDidFinishLaunching, it might be the case that controllers instantiated from Interface Builder are not yet linked to your application (so "red" and "blue" are still nil).

But to answer your initial question, what you're doing wrong is that you're calling dismissModalViewControllerAnimated: on the wrong controller! It should be like this:

[blue presentModalViewController:red animated:YES];
[red dismissModalViewControllerAnimated:YES];

Usually the "red" controller should decide to dismiss himself at some point (maybe when a "cancel" button is clicked). Then the "red" controller could call the method on self:

[self dismissModalViewControllerAnimated:YES];

If it still doesn't work, it might have something to do with the fact that the controller is presented in an animation fashion, so you might not be allowed to dismiss the controller so soon after presenting it.

React Hook Warnings for async function in useEffect: useEffect function must return a cleanup function or nothing

void operator could be used here.
Instead of:

React.useEffect(() => {
    async function fetchData() {
    }
    fetchData();
}, []);

or

React.useEffect(() => {
    (async function fetchData() {
    })()
}, []);

you could write:

React.useEffect(() => {
    void async function fetchData() {
    }();
}, []);

It is a little bit cleaner and prettier.


Async effects could cause memory leaks so it is important to perform cleanup on component unmount. In case of fetch this could look like this:

function App() {
    const [ data, setData ] = React.useState([]);

    React.useEffect(() => {
        const abortController = new AbortController();
        void async function fetchData() {
            try {
                const url = 'https://jsonplaceholder.typicode.com/todos/1';
                const response = await fetch(url, { signal: abortController.signal });
                setData(await response.json());
            } catch (error) {
                console.log('error', error);
            }
        }();
        return () => {
            abortController.abort(); // cancel pending fetch request on component unmount
        };
    }, []);

    return <pre>{JSON.stringify(data, null, 2)}</pre>;
}

Error: Configuration with name 'default' not found in Android Studio

Check the settings.gradle file. The modules which are included may be missing or in another directory. For instance, with below line in settings.gradle, gradle searches common-lib module inside your project directory:

include ':common-lib'

If it is missing, you can find and copy this module into your project or reference its path in settings.gradle file:

include ':common-lib'
project(':common-lib').projectDir = new File('<path to your module i.e. C://Libraries/common-lib>') // 

android - setting LayoutParams programmatically

after creating the view we have to add layout parameters .

change like this

TextView tv = new TextView(this);
tv.setLayoutParams(new ViewGroup.LayoutParams(
        ViewGroup.LayoutParams.WRAP_CONTENT,
        ViewGroup.LayoutParams.WRAP_CONTENT));

llview.addView(tv);
tv.setTextColor(Color.WHITE);
tv.setTextSize(2,25);
tv.setText(chat);
if (mine) {
    leftMargin = 5;
    tv.setBackgroundColor(0x7C5B77);
}
else {
    leftMargin = 50;
    tv.setBackgroundColor(0x778F6E);
}
final ViewGroup.MarginLayoutParams lpt =(MarginLayoutParams)tv.getLayoutParams();
lpt.setMargins(leftMargin,lpt.topMargin,lpt.rightMargin,lpt.bottomMargin);

Callback to a Fragment from a DialogFragment

The correct way of setting a listener to a fragment is by setting it when it is attached. The problem I had was that onAttachFragment() was never called. After some investigation I realised that I had been using getFragmentManager instead of getChildFragmentManager

Here is how I do it:

MyDialogFragment dialogFragment = MyDialogFragment.newInstance("title", "body");
dialogFragment.show(getChildFragmentManager(), "SOME_DIALOG");

Attach it in onAttachFragment:

@Override
public void onAttachFragment(Fragment childFragment) {
    super.onAttachFragment(childFragment);

    if (childFragment instanceof MyDialogFragment) {
        MyDialogFragment dialog = (MyDialogFragment) childFragment;
        dialog.setListener(new MyDialogFragment.Listener() {
            @Override
            public void buttonClicked() {

            }
        });
    }
}

How to run C program on Mac OS X using Terminal?

To do this:

  1. open terminal

  2. type in the terminal: nano ; which is a text editor available for the terminal. when you do this. something like this would appear.

  3. here you can type in your C program

  4. type in control(^) + x -> which means to exit.

  5. save the file by typing in y to save the file

  6. write the file name; e.g. helloStack.c (don't forget to add .c)

  7. when this appears, type in gcc helloStack.c

  8. then ./a.out: this should give you your result!!

How to add fonts to create-react-app based projects?

Local fonts linking to your react js may be a failure. So, I prefer to use online css file from google to link fonts. Refer the following code,

<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">

or

<style>
    @import url('https://fonts.googleapis.com/css?family=Roboto');
</style>

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

A simple way is to write:

-std=c++11

in the Other Options section of the compiler flags. You could do this on a per-project basis (Project -> Build Options), and/or set it as a default option in the Settings -> Compilers part.

Some projects may require -std=gnu++11 which is like C++11 but has some GNU extensions enabled.

If using g++ 4.9, you can use -std=c++14 or -std=gnu++14.

What is the difference between window, screen, and document in Javascript?

Well, the window is the first thing that gets loaded into the browser. This window object has the majority of the properties like length, innerWidth, innerHeight, name, if it has been closed, its parents, and more.

What about the document object then? The document object is your html, aspx, php, or other document that will be loaded into the browser. The document actually gets loaded inside the window object and has properties available to it like title, URL, cookie, etc. What does this really mean? That means if you want to access a property for the window it is window.property, if it is document it is window.document.property which is also available in short as document.property.

dom

That seems simple enough. But what happens once an IFRAME is introduced?

iframe

https with WCF error: "Could not find base address that matches scheme https"

I was using webHttpBinding and forgot to dicate the security mode of "Transport" on the binding configuration which caused the error:

  <webHttpBinding>
    <binding name="MyWCFServiceEndpoint">
      <security mode="Transport" />
    </binding>
  </webHttpBinding>

Adding this in configuration fixed the problem.

How to capture a backspace on the onkeydown event

In your function check for the keycode 8 (backspace) or 46 (delete)

Keycode information
Keycode list

session not created: This version of ChromeDriver only supports Chrome version 74 error with ChromeDriver Chrome using Selenium

I just ran into the same kind of error using RSelenium::rsDriver()'s default chromever = "latest" setting which resulted in the failed attempt to combine chromedriver 75.0.3770.8 with latest google-chrome-stable 74.0.3729.157:

session not created: This version of ChromeDriver only supports Chrome version 75

Since this obviously seems to be a recurring and pretty annoying issue, I have come up with the following workaround to always use the latest compatible ChromeDriver version:

rD <- RSelenium::rsDriver(browser = "chrome",
                          chromever =
                                  system2(command = "google-chrome-stable",
                                          args = "--version",
                                          stdout = TRUE,
                                          stderr = TRUE) %>%
                                  stringr::str_extract(pattern = "(?<=Chrome )\\d+\\.\\d+\\.\\d+\\.") %>%
                                  magrittr::extract(!is.na(.)) %>%
                                  stringr::str_replace_all(pattern = "\\.",
                                                           replacement = "\\\\.") %>%
                                  paste0("^",  .) %>%
                                  stringr::str_subset(string =
                                                              binman::list_versions(appname = "chromedriver") %>%
                                                              dplyr::last()) %>%
                                  as.numeric_version() %>%
                                  max() %>%
                                  as.character())

The above code is only tested under Linux and makes use of some tidyverse packages (install them beforehand or rewrite it in base R). For other operating systems you might have to adapt it a bit, particularly replace command = "google-chrome-stable" with the system-specific command to launch Google Chrome:

  • On macOS it should be enough to replace command = "google-chrome-stable" with command = "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome".

  • On Windows a plattform-specific bug prevents us from calling the Google Chrome binary directly to get its version number. Instead do the following:

    rD <- RSelenium::rsDriver(browser = "chrome",
                              chromever =
                                system2(command = "wmic",
                                        args = 'datafile where name="C:\\\\Program Files (x86)\\\\Google\\\\Chrome\\\\Application\\\\chrome.exe" get Version /value',
                                        stdout = TRUE,
                                        stderr = TRUE) %>%
                                stringr::str_extract(pattern = "(?<=Version=)\\d+\\.\\d+\\.\\d+\\.") %>%
                                magrittr::extract(!is.na(.)) %>%
                                stringr::str_replace_all(pattern = "\\.",
                                                         replacement = "\\\\.") %>%
                                paste0("^",  .) %>%
                                stringr::str_subset(string =
                                                            binman::list_versions(appname = "chromedriver") %>%
                                                            dplyr::last()) 
                                as.numeric_version() %>%
                                max() %>%
                                as.character())
    

Basically, the code just ensures the latest ChromeDriver version matching the major-minor-patch version number of the system's stable Google Chrome browser is passed as chromever argument. This procedure should adhere to the official ChromeDriver versioning scheme. Quote:

  • ChromeDriver uses the same version number scheme as Chrome (...)
  • Each version of ChromeDriver supports Chrome with matching major, minor, and build version numbers. For example, ChromeDriver 73.0.3683.20 supports all Chrome versions that start with 73.0.3683.

How to loop through files matching wildcard in batch file

Assuming you have two programs that process the two files, process_in.exe and process_out.exe:

for %%f in (*.in) do (
    echo %%~nf
    process_in "%%~nf.in"
    process_out "%%~nf.out"
)

%%~nf is a substitution modifier, that expands %f to a file name only. See other modifiers in https://technet.microsoft.com/en-us/library/bb490909.aspx (midway down the page) or just in the next answer.

Regex: Specify "space or start of string" and "space or end of string"

Here's what I would use:

 (?<!\S)stackoverflow(?!\S)

In other words, match "stackoverflow" if it's not preceded by a non-whitespace character and not followed by a non-whitespace character.

This is neater (IMO) than the "space-or-anchor" approach, and it doesn't assume the string starts and ends with word characters like the \b approach does.

How to run a PowerShell script

An easy way is to use PowerShell ISE, open script, run and invoke your script, function...

Enter image description here

How do I script a "yes" response for installing programs?

The 'yes' command will echo 'y' (or whatever you ask it to) indefinitely. Use it as:

yes | command-that-asks-for-input

or, if a capital 'Y' is required:

yes Y | command-that-asks-for-input

Why does git perform fast-forward merges by default?

Fast-forward merging makes sense for short-lived branches, but in a more complex history, non-fast-forward merging may make the history easier to understand, and make it easier to revert a group of commits.

Warning: Non-fast-forwarding has potential side effects as well. Please review https://sandofsky.com/blog/git-workflow.html, avoid the 'no-ff' with its "checkpoint commits" that break bisect or blame, and carefully consider whether it should be your default approach for master.

alt text
(From nvie.com, Vincent Driessen, post "A successful Git branching model")

Incorporating a finished feature on develop

Finished features may be merged into the develop branch to add them to the upcoming release:

$ git checkout develop
Switched to branch 'develop'
$ git merge --no-ff myfeature
Updating ea1b82a..05e9557
(Summary of changes)
$ git branch -d myfeature
Deleted branch myfeature (was 05e9557).
$ git push origin develop

The --no-ff flag causes the merge to always create a new commit object, even if the merge could be performed with a fast-forward. This avoids losing information about the historical existence of a feature branch and groups together all commits that together added the feature.

Jakub Narebski also mentions the config merge.ff:

By default, Git does not create an extra merge commit when merging a commit that is a descendant of the current commit. Instead, the tip of the current branch is fast-forwarded.
When set to false, this variable tells Git to create an extra merge commit in such a case (equivalent to giving the --no-ff option from the command line).
When set to 'only', only such fast-forward merges are allowed (equivalent to giving the --ff-only option from the command line).


The fast-forward is the default because:

  • short-lived branches are very easy to create and use in Git
  • short-lived branches often isolate many commits that can be reorganized freely within that branch
  • those commits are actually part of the main branch: once reorganized, the main branch is fast-forwarded to include them.

But if you anticipate an iterative workflow on one topic/feature branch (i.e., I merge, then I go back to this feature branch and add some more commits), then it is useful to include only the merge in the main branch, rather than all the intermediate commits of the feature branch.

In this case, you can end up setting this kind of config file:

[branch "master"]
# This is the list of cmdline options that should be added to git-merge 
# when I merge commits into the master branch.

# The option --no-commit instructs git not to commit the merge
# by default. This allows me to do some final adjustment to the commit log
# message before it gets commited. I often use this to add extra info to
# the merge message or rewrite my local branch names in the commit message
# to branch names that are more understandable to the casual reader of the git log.

# Option --no-ff instructs git to always record a merge commit, even if
# the branch being merged into can be fast-forwarded. This is often the
# case when you create a short-lived topic branch which tracks master, do
# some changes on the topic branch and then merge the changes into the
# master which remained unchanged while you were doing your work on the
# topic branch. In this case the master branch can be fast-forwarded (that
# is the tip of the master branch can be updated to point to the tip of
# the topic branch) and this is what git does by default. With --no-ff
# option set, git creates a real merge commit which records the fact that
# another branch was merged. I find this easier to understand and read in
# the log.

mergeoptions = --no-commit --no-ff

The OP adds in the comments:

I see some sense in fast-forward for [short-lived] branches, but making it the default action means that git assumes you... often have [short-lived] branches. Reasonable?

Jefromi answers:

I think the lifetime of branches varies greatly from user to user. Among experienced users, though, there's probably a tendency to have far more short-lived branches.

To me, a short-lived branch is one that I create in order to make a certain operation easier (rebasing, likely, or quick patching and testing), and then immediately delete once I'm done.
That means it likely should be absorbed into the topic branch it forked from, and the topic branch will be merged as one branch. No one needs to know what I did internally in order to create the series of commits implementing that given feature.

More generally, I add:

it really depends on your development workflow:

  • if it is linear, one branch makes sense.
  • If you need to isolate features and work on them for a long period of time and repeatedly merge them, several branches make sense.

See "When should you branch?"

Actually, when you consider the Mercurial branch model, it is at its core one branch per repository (even though you can create anonymous heads, bookmarks and even named branches)
See "Git and Mercurial - Compare and Contrast".

Mercurial, by default, uses anonymous lightweight codelines, which in its terminology are called "heads".
Git uses lightweight named branches, with injective mapping to map names of branches in remote repository to names of remote-tracking branches.
Git "forces" you to name branches (well, with the exception of a single unnamed branch, which is a situation called a "detached HEAD"), but I think this works better with branch-heavy workflows such as topic branch workflow, meaning multiple branches in a single repository paradigm.

Count specific character occurrences in a string

Another possibility is to work with Split:

Dim tmp() As String
tmp = Split(Expression, Delimiter)
Dim count As Integer = tmp.Length - 1

How to execute an .SQL script file using c#

This Works on Framework 4.0 or Higher. Supports "GO". Also show the error message, line, and sql command.

using System.Data.SqlClient;

        private bool runSqlScriptFile(string pathStoreProceduresFile, string connectionString)
    {
        try
        {
            string script = File.ReadAllText(pathStoreProceduresFile);

            // split script on GO command
            System.Collections.Generic.IEnumerable<string> commandStrings = Regex.Split(script, @"^\s*GO\s*$",
                                     RegexOptions.Multiline | RegexOptions.IgnoreCase);
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.Open();
                foreach (string commandString in commandStrings)
                {
                    if (commandString.Trim() != "")
                    {
                        using (var command = new SqlCommand(commandString, connection))
                        {
                        try
                        {
                            command.ExecuteNonQuery();
                        }
                        catch (SqlException ex)
                        {
                            string spError = commandString.Length > 100 ? commandString.Substring(0, 100) + " ...\n..." : commandString;
                            MessageBox.Show(string.Format("Please check the SqlServer script.\nFile: {0} \nLine: {1} \nError: {2} \nSQL Command: \n{3}", pathStoreProceduresFile, ex.LineNumber, ex.Message, spError), "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                            return false;
                        }
                    }
                    }
                }
                connection.Close();
            }
        return true;
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            return false;
        }
    }

curl: (35) error:1408F10B:SSL routines:ssl3_get_record:wrong version number

More simply in one line:

proxy=192.168.2.1:8080;curl -v example.com

eg. $proxy=192.168.2.1:8080;curl -v example.com

xxxxxxxxx-ASUS:~$ proxy=192.168.2.1:8080;curl -v https://google.com|head -c 15 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0

  • Trying 172.217.163.46:443...
  • TCP_NODELAY set
  • Connected to google.com (172.217.163.46) port 443 (#0)
  • ALPN, offering h2
  • ALPN, offering http/1.1
  • successfully set certificate verify locations:
  • CAfile: /etc/ssl/certs/ca-certificates.crt CApath: /etc/ssl/certs } [5 bytes data]
  • TLSv1.3 (OUT), TLS handshake, Client hello (1): } [512 bytes data]

SFTP Libraries for .NET

Check this out: http://www.tamirgal.com/home/dev.aspx?Item=sharpSsh

SharpSSH is a pure .NET implementation of the SSH2 client protocol suite. It provides an API for communication with SSH servers and can be integrated into any .NET application.

The library is a C# port of the JSch project from JCraft Inc. and is released under BSD style license.

SharpSSH allows you to read/write data and transfer files over SSH channels using an API similar to JSch's API. In addition, it provides some additional wrapper classes which offer even simpler abstraction for SSH communication.

SharpSSH project page at source forge: http://sourceforge.net/projects/sharpssh

mysqli_fetch_array while loop columns

Both will works perfectly in mysqli_fetch_array in while loops

while($row = mysqli_fetch_array($result,MYSQLI_BOTH)) {
    $posts[] = $row['post_id'].$row['post_title'].$row['content'];
}

(OR)

while($row = mysqli_fetch_array($result,MYSQLI_ASSOC)) {
    $posts[] = $row['post_id'].$row['post_title'].$row['content'];
}

mysqli_fetch_array() - has second argument $resulttype.

MYSQLI_ASSOC: Fetch associative array

MYSQLI_NUM: Fetch numeric array

MYSQLI_BOTH: Fetch both associative and numeric array.

Can anyone explain python's relative imports?

If you are going to call relative.py directly and i.e. if you really want to import from a top level module you have to explicitly add it to the sys.path list.
Here is how it should work:

# Add this line to the beginning of relative.py file
import sys
sys.path.append('..')

# Now you can do imports from one directory top cause it is in the sys.path
import parent

# And even like this:
from parent import Parent

If you think the above can cause some kind of inconsistency you can use this instead:

sys.path.append(sys.path[0] + "/..")

sys.path[0] refers to the path that the entry point was ran from.

Can the Twitter Bootstrap Carousel plugin fade in and out on slide transition

Came across this issue when using Bootstrap 3. My solution was to add the carousel-fade class to the carousel main DIV and slot the following CSS in, somewhere after the Bootstrap CSS is included:

.carousel-fade .item {
  opacity: 0;
  -webkit-transition: opacity 2s ease-in-out;
  -moz-transition: opacity 2s ease-in-out;
  -ms-transition: opacity 2s ease-in-out;
  -o-transition: opacity 2s ease-in-out;
  transition: opacity 2s ease-in-out;
  left: 0 !important;
}

.carousel-fade .active {
  opacity: 1 !important;
}

.carousel-fade .left {
  opacity: 0 !important;
  -webkit-transition: opacity 0.5s ease-in-out !important;
  -moz-transition: opacity 0.5s ease-in-out !important;
  -ms-transition: opacity 0.5s ease-in-out !important;
  -o-transition: opacity 0.5s ease-in-out !important;
  transition: opacity 0.5s ease-in-out !important;
}

.carousel-fade .carousel-control {
  opacity: 1 !important;
}

The style transitions that Bootstrap applies mean that you have to have the mid-stride transitions (active left, next left) quickly, otherwise the item just ends up disappearing (hence the 1/2 second transition time).

I haven't experimented with adjusting the .item and .left transition times, but they will probably need adjusting proportionally to keep the effect looking nice.

Where is my .vimrc file?

on unix vim --version tells you the various locations of the vim config files :

   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"

matplotlib does not show my drawings although I call pyplot.show()

Adding the following two lines before importing pylab seems to work for me

import matplotlib
matplotlib.use("gtk")

import sys
import pylab
import numpy as np

Inline functions in C#?

Do you mean inline functions in the C++ sense? In which the contents of a normal function are automatically copied inline into the callsite? The end effect being that no function call actually happens when calling a function.

Example:

inline int Add(int left, int right) { return left + right; }

If so then no, there is no C# equivalent to this.

Or Do you mean functions that are declared within another function? If so then yes, C# supports this via anonymous methods or lambda expressions.

Example:

static void Example() {
  Func<int,int,int> add = (x,y) => x + y;
  var result = add(4,6);  // 10
}

HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG))

Just looking at the message it sounds like one or more of the components that you reference, or one or more of their dependencies is not registered properly.

If you know which component it is you can use regsvr32.exe to register it, just open a command prompt, go to the directory where the component is and type regsvr32 filename.dll (assuming it's a dll), if it works, try to run the code again otherwise come back here with the error.

If you don't know which component it is, try re-installing/repairing the GIS software (I assume you've installed some GIS software that includes the component you're trying to use).

How do I set a path in Visual Studio?

None of the answers solved exactly my problem (the solution file I was running was trying to find xcopy to copy a dll after generation).

What solved it for me was going into menu "Project -> Properties"

Then in the window that opens choosing on the left pane: "Configuration Properties -> VC++ Directories

On the right pane under "General" choosing "Executable Directories "

And then adding:

$(SystemRoot)\system32;$(SystemRoot);$(SystemRoot)\System32\Wbem;$(SystemRoot)\System32\WindowsPowerShell\v1.0\;$(ExecutablePath)

Get local IP address

This is the best code I found to get the current IP, avoiding get VMWare host or other invalid IP address.

public string GetLocalIpAddress()
{
    UnicastIPAddressInformation mostSuitableIp = null;

    var networkInterfaces = NetworkInterface.GetAllNetworkInterfaces();

    foreach (var network in networkInterfaces)
    {
        if (network.OperationalStatus != OperationalStatus.Up)
            continue;

        var properties = network.GetIPProperties();

        if (properties.GatewayAddresses.Count == 0)
            continue;

        foreach (var address in properties.UnicastAddresses)
        {
            if (address.Address.AddressFamily != AddressFamily.InterNetwork)
                continue;

            if (IPAddress.IsLoopback(address.Address))
                continue;

            if (!address.IsDnsEligible)
            {
                if (mostSuitableIp == null)
                    mostSuitableIp = address;
                continue;
            }

            // The best IP is the IP got from DHCP server
            if (address.PrefixOrigin != PrefixOrigin.Dhcp)
            {
                if (mostSuitableIp == null || !mostSuitableIp.IsDnsEligible)
                    mostSuitableIp = address;
                continue;
            }

            return address.Address.ToString();
        }
    }

    return mostSuitableIp != null 
        ? mostSuitableIp.Address.ToString()
        : "";
}

Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server."

answer for me was to fix a gridview control which contained a template field that had a dropdownlist which was loaded with a monstrous amount of selectable items- i replaced the DDL with a label field whose data is generated from a function. (i was originally going to allow gridview editing, but have switched to allowing edits on a separate panel displaying the DDL for that field for just that record). hope this might help someone.

What's the canonical way to check for type in Python?

For more complex type validations I like typeguard's approach of validating based on python type hint annotations:

from typeguard import check_type
from typing import List

try:
    check_type('mylist', [1, 2], List[int])
except TypeError as e:
    print(e)

You can perform very complex validations in very clean and readable fashion.

check_type('foo', [1, 3.14], List[Union[int, float]])
# vs
isinstance(foo, list) and all(isinstance(a, (int, float)) for a in foo) 

Node - was compiled against a different Node.js version using NODE_MODULE_VERSION 51

I came here because I was getting this error for the quokka.js ext in vscode.

My solution: (on a mac via the terminal)

1- I went to ~/.quokka

2- I ran nano config.json

3- I copied the code from config.json into a separate file

4- I deleted the code in config.json

5- I stopped and restarted Quokka.

6- Once I confirmed that Quokka was working without errors, I deleted the config.json file code.

Can't get Python to import from a different folder

I believe you need to create a file called __init__.py in the Models directory so that python treats it as a module.

Then you can do:

from Models.user import User

You can include code in the __init__.py (for instance initialization code that a few different classes need) or leave it blank. But it must be there.

How to add a file to the last commit in git?

If you didn't push the update in remote then the simple solution is remove last local commit using following command: git reset HEAD^. Then add all files and commit again.

npm - how to show the latest version of a package

You can use:

npm show {pkg} version

(so npm show express version will return now 3.0.0rc3).

mysql select from n last rows

Take advantage of SORT and LIMIT as you would with pagination. If you want the ith block of rows, use OFFSET.

SELECT val FROM big_table
where val = someval
ORDER BY id DESC
LIMIT n;

In response to Nir: The sort operation is not necessarily penalized, this depends on what the query planner does. Since this use case is crucial for pagination performance, there are some optimizations (see link above). This is true in postgres as well "ORDER BY ... LIMIT can be done without sorting " E.7.1. Last bullet

explain extended select id from items where val = 48 order by id desc limit 10;
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
| id | select_type | table | type  | possible_keys | key     | key_len | ref   | rows | Extra       |
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
|  1 | SIMPLE      | items | const | PRIMARY       | PRIMARY | 4       | const |    1 | Using index | 
+----+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+

How do I center floated elements?

<!DOCTYPE html>
<html>
<head>
    <title>float object center</title>
    <style type="text/css">
#warp{
    width:500px;
    margin:auto;
}
.ser{
width: 200px;
background-color: #ffffff;
display: block;
float: left;
margin-right: 50px;
}
.inim{
    width: 120px;
    margin-left: 40px;
}

    </style>
</head>
<body>



<div id="warp">
            <div class="ser">
              <img class="inim" src="http://123greetingsquotes.com/wp-content/uploads/2015/01/republic-day-parade-india-images-120x120.jpg">

              </div>
           <div class="ser">
             <img class="inim" sr`enter code here`c="http://123greetingsquotes.com/wp-content/uploads/2015/01/republic-day-parade-india-images-120x120.jpg">

             </div>
        </div>

</body>
</html>

step 1

create two or more div's you want and give them a definite width like 100px for each then float it left or right

step 2

then warp these two div's in another div and give it the width of 200px. to this div apply margin auto. boom it works pretty well. check the above example.

The character encoding of the HTML document was not declared

I have same problem with the most basic situation and my problem was solved with inserting this meta in the head:

<meta charset="UTF-8">

the character encoding (which is actually UTF-8) of the html document was not declared