Programs & Examples On #Webautomation

Deals with programatically automating web browsing activities.

Automatic login script for a website on windows machine?

Well, its true that we can use Vb Script for what you intended to do. We can open an application through the code like Internet Explorer. We can navigate to site you intend for. Later we can check the element names of Text Boxes which require username and password; can set then and then Login. It works fine all of using code.

No manual interaction with the website. And eventually you will end up signing in by just double clicking the file.

To get you started :

Set objIE = CreateObject("InternetExplorer.Application")

Call objIE.Navigate("")

This will open an instance of internet explore and navigate to gmail. Rest you can learn and apply.

How can I login to a website with Python?

Maybe you want to use twill. It's quite easy to use and should be able to do what you want.

It will look like the following:

from twill.commands import *

fv("1", "email-email", "")
fv("1", "password-clear", "testpass")


You can use showforms() to list all forms once you used go… to browse to the site you want to login. Just try it from the python interpreter.

element not interactable exception in selenium web automation

I'm going to hedge this answer with this: I know it's crap.. and there's got to be a better way. (See above answers) But I tried all the suggestions here and still got nill. Ended up chasing errors, ripping the code to bits. Then I tried this:

import keyboard    
keyboard.press_and_release('tab') #repeat as needed

It's pretty insufferable and you've got to make sure that you don't lose focus otherwise you'll just be tabbing and spacing on the wrong thing.

My assumption on why the other methods didn't work for me is that I'm trying to click on something the developers didn't want a bot clicking on. So I'm not clicking on it!

What is the difference between match_parent and fill_parent?

fill_parent: The view should be as big as its parent.

now this content fill_parent is deprecated and replaced by match_parent.

Changing position of the Dialog on screen android

I used this code to show the dialog at the bottom of the screen:

Dialog dlg = <code to create custom dialog>;

Window window = dlg.getWindow();
WindowManager.LayoutParams wlp = window.getAttributes();

wlp.gravity = Gravity.BOTTOM;
wlp.flags &= ~WindowManager.LayoutParams.FLAG_DIM_BEHIND;

This code also prevents android from dimming the background of the dialog, if you need it. You should be able to change the gravity parameter to move the dialog about

private void showPictureialog() {
    final Dialog dialog = new Dialog(this,

    // Setting dialogview
    Window window = dialog.getWindow();

    window.setLayout(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

you can customize you dialog based on gravity and layout parameters change gravity and layout parameter on the basis of your requirenment

How do I format date value as yyyy-mm-dd using SSIS expression builder?

Looks like you created a separate question. I was answering your other question How to change flat file source using foreach loop container in an SSIS package? with the same answer. Anyway, here it is again.

Create two string data type variables namely DirPath and FilePath. Set the value C:\backup\ to the variable DirPath. Do not set any value to the variable FilePath.


Select the variable FilePath and select F4 to view the properties. Set the EvaluateAsExpression property to True and set the Expression property as @[User::DirPath] + "Source" + (DT_STR, 4, 1252) DATEPART("yy" , GETDATE()) + "-" + RIGHT("0" + (DT_STR, 2, 1252) DATEPART("mm" , GETDATE()), 2) + "-" + RIGHT("0" + (DT_STR, 2, 1252) DATEPART("dd" , GETDATE()), 2)


Webclient / HttpWebRequest with Basic Authentication returns 404 not found for valid URL

//This works ONLY if the server returns 401 first
//The client DOES NOT send credentials on first request
//ONLY after a 401
client.Credentials = new NetworkCredential(userName, passWord); //doesnt work

//So use THIS instead to send credentials RIGHT AWAY
string credentials = Convert.ToBase64String(
    Encoding.ASCII.GetBytes(userName + ":" + password));
client.Headers[HttpRequestHeader.Authorization] = string.Format(
    "Basic {0}", credentials);

Named colors in matplotlib

Matplotlib uses a dictionary from its module.

To print the names use:

# python2:

import matplotlib
for name, hex in matplotlib.colors.cnames.iteritems():
    print(name, hex)

# python3:

import matplotlib
for name, hex in matplotlib.colors.cnames.items():
    print(name, hex)

This is the complete dictionary:

cnames = {
'aliceblue':            '#F0F8FF',
'antiquewhite':         '#FAEBD7',
'aqua':                 '#00FFFF',
'aquamarine':           '#7FFFD4',
'azure':                '#F0FFFF',
'beige':                '#F5F5DC',
'bisque':               '#FFE4C4',
'black':                '#000000',
'blanchedalmond':       '#FFEBCD',
'blue':                 '#0000FF',
'blueviolet':           '#8A2BE2',
'brown':                '#A52A2A',
'burlywood':            '#DEB887',
'cadetblue':            '#5F9EA0',
'chartreuse':           '#7FFF00',
'chocolate':            '#D2691E',
'coral':                '#FF7F50',
'cornflowerblue':       '#6495ED',
'cornsilk':             '#FFF8DC',
'crimson':              '#DC143C',
'cyan':                 '#00FFFF',
'darkblue':             '#00008B',
'darkcyan':             '#008B8B',
'darkgoldenrod':        '#B8860B',
'darkgray':             '#A9A9A9',
'darkgreen':            '#006400',
'darkkhaki':            '#BDB76B',
'darkmagenta':          '#8B008B',
'darkolivegreen':       '#556B2F',
'darkorange':           '#FF8C00',
'darkorchid':           '#9932CC',
'darkred':              '#8B0000',
'darksalmon':           '#E9967A',
'darkseagreen':         '#8FBC8F',
'darkslateblue':        '#483D8B',
'darkslategray':        '#2F4F4F',
'darkturquoise':        '#00CED1',
'darkviolet':           '#9400D3',
'deeppink':             '#FF1493',
'deepskyblue':          '#00BFFF',
'dimgray':              '#696969',
'dodgerblue':           '#1E90FF',
'firebrick':            '#B22222',
'floralwhite':          '#FFFAF0',
'forestgreen':          '#228B22',
'fuchsia':              '#FF00FF',
'gainsboro':            '#DCDCDC',
'ghostwhite':           '#F8F8FF',
'gold':                 '#FFD700',
'goldenrod':            '#DAA520',
'gray':                 '#808080',
'green':                '#008000',
'greenyellow':          '#ADFF2F',
'honeydew':             '#F0FFF0',
'hotpink':              '#FF69B4',
'indianred':            '#CD5C5C',
'indigo':               '#4B0082',
'ivory':                '#FFFFF0',
'khaki':                '#F0E68C',
'lavender':             '#E6E6FA',
'lavenderblush':        '#FFF0F5',
'lawngreen':            '#7CFC00',
'lemonchiffon':         '#FFFACD',
'lightblue':            '#ADD8E6',
'lightcoral':           '#F08080',
'lightcyan':            '#E0FFFF',
'lightgoldenrodyellow': '#FAFAD2',
'lightgreen':           '#90EE90',
'lightgray':            '#D3D3D3',
'lightpink':            '#FFB6C1',
'lightsalmon':          '#FFA07A',
'lightseagreen':        '#20B2AA',
'lightskyblue':         '#87CEFA',
'lightslategray':       '#778899',
'lightsteelblue':       '#B0C4DE',
'lightyellow':          '#FFFFE0',
'lime':                 '#00FF00',
'limegreen':            '#32CD32',
'linen':                '#FAF0E6',
'magenta':              '#FF00FF',
'maroon':               '#800000',
'mediumaquamarine':     '#66CDAA',
'mediumblue':           '#0000CD',
'mediumorchid':         '#BA55D3',
'mediumpurple':         '#9370DB',
'mediumseagreen':       '#3CB371',
'mediumslateblue':      '#7B68EE',
'mediumspringgreen':    '#00FA9A',
'mediumturquoise':      '#48D1CC',
'mediumvioletred':      '#C71585',
'midnightblue':         '#191970',
'mintcream':            '#F5FFFA',
'mistyrose':            '#FFE4E1',
'moccasin':             '#FFE4B5',
'navajowhite':          '#FFDEAD',
'navy':                 '#000080',
'oldlace':              '#FDF5E6',
'olive':                '#808000',
'olivedrab':            '#6B8E23',
'orange':               '#FFA500',
'orangered':            '#FF4500',
'orchid':               '#DA70D6',
'palegoldenrod':        '#EEE8AA',
'palegreen':            '#98FB98',
'paleturquoise':        '#AFEEEE',
'palevioletred':        '#DB7093',
'papayawhip':           '#FFEFD5',
'peachpuff':            '#FFDAB9',
'peru':                 '#CD853F',
'pink':                 '#FFC0CB',
'plum':                 '#DDA0DD',
'powderblue':           '#B0E0E6',
'purple':               '#800080',
'red':                  '#FF0000',
'rosybrown':            '#BC8F8F',
'royalblue':            '#4169E1',
'saddlebrown':          '#8B4513',
'salmon':               '#FA8072',
'sandybrown':           '#FAA460',
'seagreen':             '#2E8B57',
'seashell':             '#FFF5EE',
'sienna':               '#A0522D',
'silver':               '#C0C0C0',
'skyblue':              '#87CEEB',
'slateblue':            '#6A5ACD',
'slategray':            '#708090',
'snow':                 '#FFFAFA',
'springgreen':          '#00FF7F',
'steelblue':            '#4682B4',
'tan':                  '#D2B48C',
'teal':                 '#008080',
'thistle':              '#D8BFD8',
'tomato':               '#FF6347',
'turquoise':            '#40E0D0',
'violet':               '#EE82EE',
'wheat':                '#F5DEB3',
'white':                '#FFFFFF',
'whitesmoke':           '#F5F5F5',
'yellow':               '#FFFF00',
'yellowgreen':          '#9ACD32'}

You could plot them like this:

import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib.colors as colors
import math

fig = plt.figure()
ax = fig.add_subplot(111)

ratio = 1.0 / 3.0
count = math.ceil(math.sqrt(len(colors.cnames)))
x_count = count * ratio
y_count = count / ratio
x = 0
y = 0
w = 1 / x_count
h = 1 / y_count

for c in colors.cnames:
    pos = (x / x_count, y / y_count)
    ax.add_patch(patches.Rectangle(pos, w, h, color=c))
    ax.annotate(c, xy=pos)
    if y >= y_count-1:
        x += 1
        y = 0
        y += 1

Changing background color of ListView items on Android

Following way very slowly in the running

mAgendaListView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

for(int i=0; i<parent.getChildCount(); i++)
     if(i == position)


Replaced by the following

int pos = 0;
int save = -1;
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
            //Always set the item clicked blue background

            if (pos == 0) {
                if (save != -1) {
                save = position;
                Log.d("Pos = 0", "Running");

            } else {
                save = position;
                pos = 0;
                Log.d("Pos # 0", "Running");

How to send image to PHP file using Ajax?

Jquery code which contains simple ajax :

   $("#product").on("input", function(event) {
      var data=$("#nameform").serialize();



Html elements you can use any element:

     <form id="nameform">
     <input type="text" name="product" id="product">

php Code:

  $pdo=new PDO("mysql:host=localhost;dbname=onlineshooping","root","");


  $stmtcat=$pdo->prepare('SELECT * from products where Catagory =?');


   echo "<tr>";
   echo "<td><a href=./pages/productsinfo.php?id=".$iddb."> $namedb</a> </td>".'<br>'; 
   echo "<td><pre>$pricedb</pre></td>";
   echo "<td><pre>    $colordb</pre>";
   echo "</tr>";

The easy way

jQuery: click function exclude children.

Or you can do also:

$('.example').on('click', function(e) { 
   if( != this ) 
       return false;

   // ... //

Getting the difference between two Dates (months/days/hours/minutes/seconds) in Swift

If your purpose is to get the exact day number between two dates, you can work around this issue like this:

// Assuming that firstDate and secondDate are defined
// ...

var calendar: NSCalendar = NSCalendar.currentCalendar()

// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDayForDate(firstDate)
let date2 = calendar.startOfDayForDate(secondDate)

let flags = NSCalendarUnit.DayCalendarUnit
let components = calendar.components(flags, fromDate: date1, toDate: date2, options: nil)  // This will return the number of day(s) between dates

How can I scale an image in a CSS sprite

2018 here. Use background-size with percentage.


This assumes a single row of sprites. The width of your sheet should be a number that is evenly divisible by 100 + width of one sprite. If you have 30 sprites that are 108x108 px, then add extra blank space to the end to make the final width 5508px (50*108 + 108).


    height: 30px;  /* Set this to anything. It will scale. */
    width: 30px; /* Match height. This assumes square sprites. */
    background-size: 5100% 100%; /*  5100% because 51 sprites. */

/* Each image increases by 2% because we used 50+1 sprites. 
   If we had used 20+1 sprites then % increase would be 5%. */

    background-position: 0% 0;

    background-position: 16% 0; /* (9-1) x 2 = 16 */


<div class ="icon first_image"></div>
<div class ="icon ninth_image"></div>

Disable validation of HTML5 form elements

If you want to disable client side validation for a form in HTML5 add a novalidate attribute to the form element. Ex:

<form method="post" action="/foo" novalidate>...</form>


How to refer to relative paths of resources when working with a code repository

I got stumped here a bit. Wanted to package some resource files into a wheel file and access them. Did the packaging using manifest file, but pip install was not installing it unless it was a sub directory. Hoping these sceen shots will help

+-- cnn_client
¦   +--
¦   +--
¦   +-- resources
¦   ¦   +-- mscoco_complete_label_map.pbtxt
¦   ¦   +-- retinanet_complete_label_map.pbtxt
¦   ¦   +--
¦   +--

recursive-include cnn_client/resources *

Created a weel using standard . pip installed the wheel file. After installation checked if resources are installed. They are

ls /usr/local/lib/python2.7/dist-packages/cnn_client/resources


In to access these files. from

templates_dir = os.path.join(os.path.dirname(__file__), 'resources')
 file_path = os.path.join(templates_dir, \
        s = open(file_path, 'r').read()

And it works.

Find package name for Android apps to use Intent to launch Market app from web

Once you have the package name, as described Chris Smith's answer, you could/should use an intent url for the link. It's a special format URL that will launch the package if the user has already installed it, or open the play store at the application's page if not...


The app needs to support this, with an activity tagged as browsable, but many will.

How do you change the document font in LaTeX?

This article might be helpful with changing fonts.

From the article:

The commands to change font attributes are illustrated by the following example:


This series of commands set the current font to medium weight italic garamond 12pt type with 15pt leading in the T1 encoding scheme, and the \selectfont command causes LaTeX to look in its mapping scheme for a metric corresponding to these attributes.

Generating unique random numbers (integers) between 0 and 'x'

Math.floor(Math.random() * (limit+1))

Math.random() generates a floating point number between 0 and 1, Math.floor() rounds it down to an integer.

By multiplying it by a number, you effectively make the range 0..number-1. If you wish to generate it in range from num1 to num2, do:

Math.floor(Math.random() * (num2-num1 + 1) + num1)

To generate more numbers, just use a for loop and put results into an array or write them into the document directly.

Moving up one directory in Python

Obviously that os.chdir('..') is the right answer here. But just FYI, if in the future you come across situation when you have to extensively manipulate directories and paths, here is a great package (Unipath) which lets you treat them as Python objects:

so that you could do something like this:

>>> from unipath import Path
>>> p = Path("/usr/lib/python2.5/")
>>> p.parent
>>> p.ext

Android- create JSON Array and JSON Object

            Map<String, String> params = new HashMap<String, String>();

            //** Temp array
            List<String[]> tmpArray = new ArrayList<>();
            tmpArray.add(new String[]{"b001","book1"}); 
            tmpArray.add(new String[]{"b002","book2"}); 

            //** Json Array Example
            JSONArray jrrM = new JSONArray();
            for(int i=0; i<tmpArray.size(); i++){
                JSONArray jrr = new JSONArray();

           //Json Object Example
           JSONObject jsonObj = new JSONObject();
            try {
                jsonObj.put("rows", jrrM);

            }catch (JSONException ex){

            // Bundles them
            params.put("user", "guest");
            params.put("tb", "book_store");
            params.put("data", jsonObj.toString());

           // Now you can send them to the server.

Convert PDF to image with high resolution

In ImageMagick, you can do "supersampling". You specify a large density and then resize down as much as desired for the final output size. For example with your image:

convert -density 600 test.pdf -background white -flatten -resize 25% test.png

enter image description here

Download the image to view at full resolution for comparison..

I do not recommend saving to JPG if you are expecting to do further processing.

If you want the output to be the same size as the input, then resize to the inverse of the ratio of your density to 72. For example, -density 288 and -resize 25%. 288=4*72 and 25%=1/4

The larger the density the better the resulting quality, but it will take longer to process.

Combining CSS Pseudo-elements, ":after" the ":last-child"

I do like this for list items in <menu> elements. Consider the following markup:

  <li><a href="/member/profile">Profile</a></li>
  <li><a href="/member/options">Options</a></li>
  <li><a href="/member/logout">Logout</a></li>

I style it with the following CSS:

menu > li {
  display: inline;

menu > li::after {
  content: ' | ';

menu > li:last-child::after {
  content: '';

This will display:

Profile | Options | Logout

And this is possible because of what Martin Atkins explained on his comment

Note that in CSS 2 you would use :after, not ::after. If you use CSS 3, use ::after (two semi-columns) because ::after is a pseudo-element (a single semi-column is for pseudo-classes).

How to get user name using Windows authentication in

It depends on the configuration of the application as well as on IIS as this gentleman in the below link has rightfully explained. Please see his article below

Intellij IDEA Java classes not auto compiling on save

I had the same issue. I was using the "Power save mode", which prevents from compiling incrementally and showing compilation errors.

How to call multiple functions with @click in vue?

to add an anomymous function to do that may be an alternative:

<div v-on:click="return function() { fn1('foo');fn2('bar'); }()"> </div> 

Copying files into the application folder at compile time

You can also put the files or links into the root of the solution explorer and then set the files properties:

Build action = Content


Copy to Output Directory = Copy if newer (for example)

For a link drag the file from the windows explorer into the solution explorer holding down the shift and control keys.

enter image description here

How to select true/false based on column value?

Use a CASE. I would post the specific code, but need more information than is supplied in the post - such as the data type of EntityProfile and what is usually stored in it. Something like:

CASE WHEN EntityProfile IS NULL THEN 'False' ELSE 'True' END

Edit - the entire SELECT statement, as per the info in the comments:

SELECT EntityID, EntityName, 
       CASE WHEN EntityProfile IS NULL THEN 'False' ELSE 'True' END AS HasProfile
FROM Entity

No LEFT JOIN necessary in this case...

Static link of shared library function in gcc

In gcc, this isn't supported. In fact, this isn't supported in any existing compiler/linker i'm aware of.

Iterating over every two elements in a list

you can use more_itertools package.

import more_itertools

lst = range(1, 7)
for i, j in more_itertools.chunked(lst, 2):
    print(f'{i} + {j} = {i+j}')

WELD-001408: Unsatisfied dependencies for type Customer with qualifiers @Default

Your Customer class has to be discovered by CDI as a bean. For that you have two options:

  1. Put a bean defining annotation on it. As @Model is a stereotype it's why it does the trick. A qualifier like @Named is not a bean defining annotation, reason why it doesn't work

  2. Change the bean discovery mode in your bean archive from the default "annotated" to "all" by adding a beans.xml file in your jar.

Keep in mind that @Named has only one usage : expose your bean to the UI. Other usages are for bad practice or compatibility with legacy framework.

HTTP Error 401.2 - Unauthorized You are not authorized to view this page due to invalid authentication headers

Open Project properties by selecting project then go to

View>Properties Windows

and make sure Anonymous Authentication is Enabled

enter image description here

How to do exponential and logarithmic curve fitting in Python? I found only polynomial fitting

Well I guess you can always use:

np.log   -->  natural log
np.log10 -->  base 10
np.log2  -->  base 2

Slightly modifying IanVS's answer:

import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit

def func(x, a, b, c):
  #return a * np.exp(-b * x) + c
  return a * np.log(b * x) + c

x = np.linspace(1,5,50)   # changed boundary conditions to avoid division by 0
y = func(x, 2.5, 1.3, 0.5)
yn = y + 0.2*np.random.normal(size=len(x))

popt, pcov = curve_fit(func, x, yn)

plt.plot(x, yn, 'ko', label="Original Noised Data")
plt.plot(x, func(x, *popt), 'r-', label="Fitted Curve")

This results in the following graph:

enter image description here

How to Use Order By for Multiple Columns in Laravel 4?

Simply invoke orderBy() as many times as you need it. For instance:

User::orderBy('name', 'DESC')
    ->orderBy('email', 'ASC')

Produces the following query:

SELECT * FROM `users` ORDER BY `name` DESC, `email` ASC

How to render a DateTime object in a Twig template

Although you can use the

{{ game.gameDate|date('Y-m-d') }}

approach, keep in mind that this version does not honor the user locale, which should not be a problem with a site used by only users of one nationality. International users should display the game date totally different, like extending the \DateTime class, and adding a __toString() method to it that checks the locale and acts accordingly.


As pointed out by @Nic in a comment, if you use the Intl extension of Twig, you will have a localizeddate filter available, which shows the date in the user’s locale. This way you can drop my previous idea of extending \DateTime.

Trying to SSH into an Amazon Ec2 instance - permission error

ssh -i /.pem user@host-machine-IP

I think it's because either you have entered wrong credentials or, you are using a public key rather than private key or, your port permissions are open for ALL to ssh. This is bad for Amazon.

How to enter ssh password using bash?

Double check if you are not able to use keys.

Otherwise use expect:

#!/usr/bin/expect -f
spawn ssh [email protected]
expect "assword:"
send "mypassword\r"

What is the difference between Tomcat, JBoss and Glassfish?

Both JBoss and Tomcat are Java servlet application servers, but JBoss is a whole lot more. The substantial difference between the two is that JBoss provides a full Java Enterprise Edition (Java EE) stack, including Enterprise JavaBeans and many other technologies that are useful for developers working on enterprise Java applications.

Tomcat is much more limited. One way to think of it is that JBoss is a Java EE stack that includes a servlet container and web server, whereas Tomcat, for the most part, is a servlet container and web server.

How to execute a JavaScript function when I have its name as a string

The answer to this other question shows you how to do that: Javascript equivalent of Python's locals()?

Basically, you can say

window["foo"](arg1, arg2);

or as many others have suggested, you can just use eval:

eval(fname)(arg1, arg2);

although this is extremely unsafe unless you're absolutely sure about what you're eval-ing.

Documentation for using JavaScript code inside a PDF file

I'm pretty sure it's an Adobe standard, bearing in mind the whole PDF standard is theirs to begin with; despite being open now.

My guess would be no for all PDF viewers supporting it, as some definitely will not have a JS engine. I doubt you can rely on full support outside the most recent versions of Acrobat (Reader). So I guess it depends on how you imagine it being used, if mainly via a browser display, then the majority of the market is catered for by Acrobat (Reader) and Chrome's built-in viewer - dare say there is documentation on whether Chrome's PDF viewer supports JS fully.

Call to a member function fetch_assoc() on boolean in <path>

You have to update the php.ini config file with in your host provider's server, trust me on this, more than likely there is nothing wrong with your code. It took me almost a month and a half to realize that most hosting servers are not up to date on php.ini files, eg. php 5.5 or later, I believe.

angular ng-repeat in reverse

This is what i used:

<alert ng-repeat="alert in alerts.slice().reverse()" type="alert.type" close="alerts.splice(index, 1)">{{$index + 1}}: {{alert.msg}}</alert>


My answer was OK for old version of Angular. Now, you should be using

ng-repeat="friend in friends | orderBy:'-'"


ng-repeat="friend in friends | orderBy:'+':true"


Casting a number to a string in TypeScript

"Casting" is different than conversion. In this case, window.location.hash will auto-convert a number to a string. But to avoid a TypeScript compile error, you can do the string conversion yourself:

window.location.hash = ""+page_number; 
window.location.hash = String(page_number); 

These conversions are ideal if you don't want an error to be thrown when page_number is null or undefined. Whereas page_number.toString() and page_number.toLocaleString() will throw when page_number is null or undefined.

When you only need to cast, not convert, this is how to cast to a string in TypeScript:

window.location.hash = <string>page_number; 
// or 
window.location.hash = page_number as string;

The <string> or as string cast annotations tell the TypeScript compiler to treat page_number as a string at compile time; it doesn't convert at run time.

However, the compiler will complain that you can't assign a number to a string. You would have to first cast to <any>, then to <string>:

window.location.hash = <string><any>page_number;
// or
window.location.hash = page_number as any as string;

So it's easier to just convert, which handles the type at run time and compile time:

window.location.hash = String(page_number); 

(Thanks to @RuslanPolutsygan for catching the string-number casting issue.)

How to display a "busy" indicator with jQuery?

I did it in my project:

Global Events in application.js:

$(document).bind("ajaxSend", function(){
 }).bind("ajaxComplete", function(){

"loading" is the element to show and hide!


Ruby: character to ascii from a string

puts "string".split('').map(&:ord).to_s

How to find the length of an array in shell?

$ a=(1 2 3 4)
$ echo ${#a[@]}

Mocking a function to raise an Exception to test an except block

Your mock is raising the exception just fine, but the error.resp.status value is missing. Rather than use return_value, just tell Mock that status is an attribute:

barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')

Additional keyword arguments to Mock() are set as attributes on the resulting object.

I put your foo and bar definitions in a my_tests module, added in the HttpError class so I could use it too, and your test then can be ran to success:

>>> from my_tests import foo, HttpError
>>> import mock
>>> with mock.patch('') as barMock:
...     barMock.side_effect = HttpError(mock.Mock(status=404), 'not found')
...     result =
404 - 
>>> result is None

You can even see the print '404 - %s' % error.message line run, but I think you wanted to use error.content there instead; that's the attribute HttpError() sets from the second argument, at any rate.

Opening port 80 EC2 Amazon web services

Some quick tips:

  1. Disable the inbuilt firewall on your Windows instances.
  2. Use the IP address rather than the DNS entry.
  3. Create a security group for tcp ports 1 to 65000 and for source It's obviously not to be used for production purposes, but it will help avoid the Security Groups as a source of problems.
  4. Check that you can actually ping your server. This may also necessitate some Security Group modification.

Create an instance of a class from a string

To create an instance of a class from another project in the solution, you can get the assembly indicated by the name of any class (for example BaseEntity) and create a new instance:

  var newClass = System.Reflection.Assembly.GetAssembly(typeof(BaseEntity)).CreateInstance("MyProject.Entities.User");

How can I get just the first row in a result set AFTER ordering?

This question is similar to How do I limit the number of rows returned by an Oracle query after ordering?.

It talks about how to implement a MySQL limit on an oracle database which judging by your tags and post is what you are using.

The relevant section is:

select *
  ( select * 
  from emp 
  order by sal desc ) 
  where ROWNUM <= 5;

Access Database opens as read only

Check that there are no missing references - to do this, go to the database window and click on "Modules", then "Design", then select the menu "Tools" and then "References". Or try doing a compile and see if it compiles fully (go to the Debug menu then select Compile) - it might tell you of a missing reference e.g. Microsoft Office 11.0 Object Library. Select References from the Tools menu again and see if any references are ticked and say "MISSING:". In some cases you can select a different version from the list, if 11.0 is missing, look for version 12.0 then recompile. That usually does the trick for me.

R - test if first occurrence of string1 is followed by string2

> grepl("^[^_]+_1",s)
> grepl("^[^_]+_2",s)
[1] TRUE

basically, look for everything at the beginning except _, and then the _2.

+1 to @Ananda_Mahto for suggesting grepl instead of grep.

MySQL vs MongoDB 1000 reads

Honestly even if MongoDB is slower, MongoDB definitely makes me and you code faster.... no need to worry about silly table columns, row or entity migrations...

With MongoDB, you just instantiate a class and save!

How do you remove an array element in a foreach loop?

foreach($display_related_tags as $key => $tag_name)
    if($tag_name == $found_tag['name'])

Adjust UILabel height to text

The solution suggested by Anorak as a computed property in an extension for UILabel:

extension UILabel
var optimalHeight : CGFloat
            let label = UILabel(frame: CGRectMake(0, 0, self.frame.width, CGFloat.max))
            label.numberOfLines = 0
            label.lineBreakMode = self.lineBreakMode
            label.font = self.font
            label.text = self.text


            return label.frame.height


self.brandModelLabel.frame.size.height = self.brandModelLabel.optimalHeight

Cannot set property 'innerHTML' of null

maybe this will work: document.getElementsByTagName("body")[0].innerHTML

SQL Server: Filter output of sp_who2

Similar to KyleMit answer, its possible to select directly the tables used by SP_WHO2, although I think it's only need dbo.sysprocesses table.

If someone open this SP, it can understand what it does. This is my best select to have a similar output as SP_WHO2

select convert(char(5),sp.spid) as SPID
        ,  CASE lower(sp.status)
                 When 'sleeping' Then lower(sp.status)
                 Else  upper(sp.status)
              END as Status
        , convert(sysname, rtrim(sp.loginame)) as LOGIN
        , CASE sp.hostname
                 When Null  Then '  .'
                 When ' ' Then '  .'
                 Else    rtrim(sp.hostname)
              END as HostName
        , CASE isnull(convert(char(5),sp.blocked),'0')
                 When '0' Then '  .'
                 Else isnull(convert(char(5),sp.blocked),'0')
              END as BlkBy
        , case when sp.dbid = 0 then null when sp.dbid <> 0 then db_name(sp.dbid) end as DBName
        , sp.cmd as Command
        , sp.cpu as CPUTime
        , sp.physical_io as DiskIO
        , sp.last_batch as LastBatch
        , sp.program_name as ProgramName 
        from master.dbo.sysprocesses sp (nolock)

Over this select, you can select the fields you need and have the order you want.

Pass Hidden parameters using response.sendRedirect()

Generally, you cannot send a POST request using sendRedirect() method. You can use RequestDispatcher to forward() requests with parameters within the same web application, same context.

RequestDispatcher dispatcher = servletContext().getRequestDispatcher("test.jsp");
dispatcher.forward(request, response);

The HTTP spec states that all redirects must be in the form of a GET (or HEAD). You can consider encrypting your query string parameters if security is an issue. Another way is you can POST to the target by having a hidden form with method POST and submitting it with javascript when the page is loaded.

Flatten nested dictionaries, compressing keys

def flatten_nested_dict(_dict, _str=''):
    recursive function to flatten a nested dictionary json
    ret_dict = {}
    for k, v in _dict.items():
        if isinstance(v, dict):
            ret_dict.update(flatten_nested_dict(v, _str = '_'.join([_str, k]).strip('_')))
        elif isinstance(v, list):
            for index, item in enumerate(v):
                if isinstance(item, dict):
                    ret_dict.update(flatten_nested_dict(item,  _str= '_'.join([_str, k, str(index)]).strip('_')))
                    ret_dict['_'.join([_str, k, str(index)]).strip('_')] = item
            ret_dict['_'.join([_str, k]).strip('_')] = v
    return ret_dict

facebook: permanent Page Access Token?

I made a PHP script to make it easier. Create an app. In the Graph API Explorer select your App and get a user token with manage_pages and publish_pages permission. Find your page's ID at the bottom of its About page. Fill in the config vars and run the script.


echo generate_token($args);

function generate_token($args){
    $r=json_decode(file_get_contents("{$args['appid']}&client_secret={$args['appsecret']}&fb_exchange_token={$args['usertoken']}")); // get long-lived token
    $r=json_decode(file_get_contents("{$longtoken}")); // get user id
    $r=json_decode(file_get_contents("{$userid}/accounts?access_token={$longtoken}")); // get permanent token
    foreach($r->data as $d) if($d->id==$args['pageid']) return $d->access_token;

JUnit 5: How to assert an exception is thrown?

In Java 8 and JUnit 5 (Jupiter) we can assert for exceptions as follows. Using org.junit.jupiter.api.Assertions.assertThrows

public static < T extends Throwable > T assertThrows(Class< T > expectedType, Executable executable)

Asserts that execution of the supplied executable throws an exception of the expectedType and returns the exception.

If no exception is thrown, or if an exception of a different type is thrown, this method will fail.

If you do not want to perform additional checks on the exception instance, simply ignore the return value.

public void itShouldThrowNullPointerExceptionWhenBlahBlah() {
            //do whatever you want to do here
            //ex : objectName.thisMethodShoulThrowNullPointerExceptionForNullParameter(null);

That approach will use the Functional Interface Executable in org.junit.jupiter.api.

Refer :

Spring Boot how to hide passwords in properties file

To the already proposed solutions I can add an option to configure an external Secrets Manager such as Vault.

  1. Configure Vault Server vault server -dev (Only for DEV and not for PROD)
  2. Write secrets vault write secret/somename key1=value1 key2=value2
  3. Verify secrets vault read secret/somename

Add the following dependency to your SpringBoot project:


Add Vault config properties:${VAULT_TOKEN}

Pass VAULT_TOKEN as an environment variable.

Refer to the documentation here.

There is a Spring Vault project which is also can be used for accessing, storing and revoking secrets.



Configuring Vault Template:

class VaultConfiguration extends AbstractVaultConfiguration {

  public VaultEndpoint vaultEndpoint() {
    return new VaultEndpoint();

  public ClientAuthentication clientAuthentication() {
    return new TokenAuthentication("…");

Inject and use VaultTemplate:

public class Example {

  private VaultOperations operations;

  public void writeSecrets(String userId, String password) {
      Map<String, String> data = new HashMap<String, String>();
      data.put("password", password);
      operations.write(userId, data);

  public Person readSecrets(String userId) {
      VaultResponseSupport<Person> response =, Person.class);
      return response.getBody();

Use Vault PropertySource:

@VaultPropertySource(value = "aws/creds/s3",
  propertyNamePrefix = "aws."
  renewal = Renewal.RENEW)
public class Config {


Usage example:

public class S3Client {

  // inject the actual values
  private String awsAccessKey;
  private String awsSecretKey;

  public InputStream getFileFromS3(String filenname) {
    // …

gson throws MalformedJsonException

I suspect that result1 has some characters at the end of it that you can't see in the debugger that follow the closing } character. What's the length of result1 versus result2? I'll note that result2 as you've quoted it has 169 characters.

GSON throws that particular error when there's extra characters after the end of the object that aren't whitespace, and it defines whitespace very narrowly (as the JSON spec does) - only \t, \n, \r, and space count as whitespace. In particular, note that trailing NUL (\0) characters do not count as whitespace and will cause this error.

If you can't easily figure out what's causing the extra characters at the end and eliminate them, another option is to tell GSON to parse in lenient mode:

Gson gson = new Gson();
JsonReader reader = new JsonReader(new StringReader(result1));
Userinfo userinfo1 = gson.fromJson(reader, Userinfo.class);

How to get error information when HttpWebRequest.GetResponse() fails

I came across this question when trying to check if a file existed on an FTP site or not. If the file doesn't exist there will be an error when trying to check its timestamp. But I want to make sure the error is not something else, by checking its type.

The Response property on WebException will be of type FtpWebResponse on which you can check its StatusCode property to see which FTP error you have.

Here's the code I ended up with:

    public static bool FileExists(string host, string username, string password, string filename)
        // create FTP request
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://" + host + "/" + filename);
        request.Credentials = new NetworkCredential(username, password);

        // we want to get date stamp - to see if the file exists
        request.Method = WebRequestMethods.Ftp.GetDateTimestamp;

            FtpWebResponse response = (FtpWebResponse)request.GetResponse();
            var lastModified = response.LastModified;

            // if we get the last modified date then the file exists
            return true;
        catch (WebException ex)
            var ftpResponse = (FtpWebResponse)ex.Response;

            // if the status code is 'file unavailable' then the file doesn't exist
            // may be different depending upon FTP server software
            if (ftpResponse.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable)
                return false;

            // some other error - like maybe internet is down

Selenium Webdriver submit() vs click()

The submit() function is there to make life easier. You can use it on any element inside of form tags to submit that form.

You can also search for the submit button and use click().

So the only difference is click() has to be done on the submit button and submit() can be done on any form element.

It's up to you.


If your script is inside head tag in html file, try to put it inside body tag. CreateElement while script is inside head tag will give you a null warning


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

How do I validate a date in rails?

Using the chronic gem:

class MyModel < ActiveRecord::Base
  validate :valid_date?

  def valid_date?
    unless Chronic.parse(from_date)
      errors.add(:from_date, "is missing or invalid")


Convert ASCII TO UTF-8 Encoding

Use utf8_encode()

Man page can be found here

Also read this article from Joel on Software. It provides an excellent explanation if what Unicode is and how it works.

WPF Timer Like C# Timer

With Dispatcher you will need to include

using System.Windows.Threading;

Also note that if you right-click DispatcherTimer and click Resolve it should add the appropriate references.

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

Radu Simionescu's answer worked for me. Thank you. For those who are unable to see the ip address of their android device, go to Settings > Wireless > Wi-Fi and then long press the wifi which you are connected to. Then select Modify network config check on Show Advance Options and the scroll to IP address section.

After installing adb in your system, do run killadd adb and adb start-server to refresh adb. Sometimes we could get issues like here

Getting cursor position in Python

Using the standard ctypes library, this should yield the current on screen mouse coordinates without any third party modules:

from ctypes import windll, Structure, c_long, byref

class POINT(Structure):
    _fields_ = [("x", c_long), ("y", c_long)]

def queryMousePosition():
    pt = POINT()
    return { "x": pt.x, "y": pt.y}

pos = queryMousePosition()

I should mention that this code was taken from an example found here So credit goes to for this solution.

What method in the String class returns only the first N characters?

Partially for the sake of summarization (excluding LINQ solution), here's two one-liners that address the int maxLength caveat of allowing negative values and also the case of null string:

  1. The Substring way (from Paul Ruane's answer):
public static string Truncate(this string s, uint maxLength) =>
    s?.Substring(0, Math.Min(s.Length, (int)maxLength));
  1. The Remove way (from kbrimington's answer):
public static string Truncate(this string s, uint maxLength) =>
    s?.Length > maxLength ? s.Remove((int)maxLength) : s;

What is com.sun.proxy.$Proxy

  1. Proxies are classes that are created and loaded at runtime. There is no source code for these classes. I know that you are wondering how you can make them do something if there is no code for them. The answer is that when you create them, you specify an object that implements InvocationHandler, which defines a method that is invoked when a proxy method is invoked.

  2. You create them by using the call

    Proxy.newProxyInstance(classLoader, interfaces, invocationHandler)

    The arguments are:

    1. classLoader. Once the class is generated, it is loaded with this class loader.
    2. interfaces. An array of class objects that must all be interfaces. The resulting proxy implements all of these interfaces.
    3. invocationHandler. This is how your proxy knows what to do when a method is invoked. It is an object that implements InvocationHandler. When a method from any of the supported interfaces, or hashCode, equals, or toString, is invoked, the method invoke is invoked on the handler, passing the Method object for the method to be invoked and the arguments passed.

    For more on this, see the documentation for the Proxy class.

  3. Every implementation of a JVM after version 1.3 must support these. They are loaded into the internal data structures of the JVM in an implementation-specific way, but it is guaranteed to work.

How to use "not" in xpath?

not() is a function in xpath (as opposed to an operator), so

//a[not(contains(@id, 'xx'))]

E: gnupg, gnupg2 and gnupg1 do not seem to be installed, but one of them is required for this operation

I faced the same issue:

E: gnupg, gnupg2 and gnupg1 do not seem to be installed, but one of them is required for this operation

I resolved by using the following commands:

apt-get update
apt-get install gnupg

Fully custom validation error message with Rails

Here is my code that can be useful for you in case you still need it: My model:

validates :director, acceptance: {message: "^Please confirm that you are a director of the company."}, on: :create, if: :is_director?

Then I have created a helper to show messages:

module ErrorHelper
  def error_messages!
    return "" unless error_messages?
    messages = { |msg|
       if msg.present? && !msg.index("^").nil?
         content_tag(:p, msg.slice((msg.index("^")+1)..-1))
         content_tag(:p, msg)

    html = <<-HTML
      <div class="general-error alert show">


  def error_messages?

Adding hours to JavaScript Date object?

If you would like to do it in a more functional way (immutability) I would return a new date object instead of modifying the existing and I wouldn't alter the prototype but create a standalone function. Here is the example:

function addHoursToDate(date, hours) {
  return new Date(new Date(date).setHours(date.getHours() + hours));

function addHoursToDate(date: Date, hours: number): Date {
  return new Date(new Date(date).setHours(date.getHours() + hours));

let myDate = new Date();


Change background image opacity

What I did is:

<div id="bg-image"></div>
<div class="container">
    <h1>Hello World!</h1>


html {
    height: 100%;
    width: 100%;
body {
    height: 100%;
    width: 100%;
#bg-image {
    height: 100%;
    width: 100%;
    position: absolute;
    background-image: url(images/background.jpg);
    background-position: center center;
    background-repeat: no-repeat;
    background-size: cover;
    opacity: 0.3;

Scatter plot and Color mapping in Python

Here is an example

import numpy as np
import matplotlib.pyplot as plt

x = np.random.rand(100)
y = np.random.rand(100)
t = np.arange(100)

plt.scatter(x, y, c=t)

Here you are setting the color based on the index, t, which is just an array of [1, 2, ..., 100]. enter image description here

Perhaps an easier-to-understand example is the slightly simpler

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(100)
y = x
t = x
plt.scatter(x, y, c=t)

enter image description here

Note that the array you pass as c doesn't need to have any particular order or type, i.e. it doesn't need to be sorted or integers as in these examples. The plotting routine will scale the colormap such that the minimum/maximum values in c correspond to the bottom/top of the colormap.


You can change the colormap by adding

import as cm
plt.scatter(x, y, c=t, cmap=cm.cmap_name)

Importing is optional as you can call colormaps as cmap="cmap_name" just as well. There is a reference page of colormaps showing what each looks like. Also know that you can reverse a colormap by simply calling it as cmap_name_r. So either

plt.scatter(x, y, c=t, cmap=cm.cmap_name_r)
# or
plt.scatter(x, y, c=t, cmap="cmap_name_r")

will work. Examples are "jet_r" or cm.plasma_r. Here's an example with the new 1.5 colormap viridis:

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(100)
y = x
t = x
fig, (ax1, ax2) = plt.subplots(1, 2)
ax1.scatter(x, y, c=t, cmap='viridis')
ax2.scatter(x, y, c=t, cmap='viridis_r')

enter image description here


You can add a colorbar by using

plt.scatter(x, y, c=t, cmap='viridis')

enter image description here

Note that if you are using figures and subplots explicitly (e.g. fig, ax = plt.subplots() or ax = fig.add_subplot(111)), adding a colorbar can be a bit more involved. Good examples can be found here for a single subplot colorbar and here for 2 subplots 1 colorbar.

How to SUM parts of a column which have same text value in different column in the same row

This can be done by using SUMPRODUCT as well. Update the ranges as you see fit


A2:A7 = First name range

B2:B7 = Last Name Range

C2:C7 = Numbers Range

This will find all the names with the same first and last name and sum the numbers in your numbers column

matplotlib set yaxis label size

If you are using the 'pylab' for interactive plotting you can set the labelsize at creation time with pylab.ylabel('Example', fontsize=40).

If you use pyplot programmatically you can either set the fontsize on creation with ax.set_ylabel('Example', fontsize=40) or afterwards with ax.yaxis.label.set_size(40).

How to resolve a Java Rounding Double issue

It's quite simple.

Use the %.2f operator for output. Problem solved!

For example:

int a = 877.8499999999999;
System.out.printf("Formatted Output is: %.2f", a);

The above code results in a print output of: 877.85

The %.2f operator defines that only TWO decimal places should be used.

Rownum in postgresql

If you just want a number to come back try this.

create temp sequence temp_seq;
SELECT inline_v1.ROWNUM,inline_v1.c1
select nextval('temp_seq') as ROWNUM, c1 
from sometable

You can add a order by to the inline_v1 SQL so your ROWNUM has some sequential meaning to your data.

select nextval('temp_seq') as ROWNUM, c1 
from sometable
ORDER BY c1 desc;

Might not be the fastest, but it's an option if you really do need them.

How to use Jackson to deserialise an array of objects

here is an utility which is up to transform json2object or Object2json, whatever your pojo (entity T)

import java.util.List;

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

 * @author TIAGO.MEDICI
public class JsonUtils {

    public static boolean isJSONValid(String jsonInString) {
        try {
            final ObjectMapper mapper = new ObjectMapper();
            return true;
        } catch (IOException e) {
            return false;

    public static String serializeAsJsonString(Object object) throws JsonGenerationException, JsonMappingException, IOException {
        ObjectMapper objMapper = new ObjectMapper();
        StringWriter sw = new StringWriter();
        objMapper.writeValue(sw, object);
        return sw.toString();

    public static String serializeAsJsonString(Object object, boolean indent) throws JsonGenerationException, JsonMappingException, IOException {
        ObjectMapper objMapper = new ObjectMapper();
        if (indent == true) {

        StringWriter stringWriter = new StringWriter();
        objMapper.writeValue(stringWriter, object);
        return stringWriter.toString();

    public static <T> T jsonStringToObject(String content, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException {
        T obj = null;
        ObjectMapper objMapper = new ObjectMapper();
        obj = objMapper.readValue(content, clazz);
        return obj;

    public static <T> T jsonStringToObjectArray(String content) throws JsonParseException, JsonMappingException, IOException {
        T obj = null;
        ObjectMapper mapper = new ObjectMapper();
        obj = mapper.readValue(content, new TypeReference<List>() {
        return obj;

    public static <T> T jsonStringToObjectArray(String content, Class<T> clazz) throws JsonParseException, JsonMappingException, IOException {
        T obj = null;
        ObjectMapper mapper = new ObjectMapper();
        mapper = new ObjectMapper().configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
        obj = mapper.readValue(content, mapper.getTypeFactory().constructCollectionType(List.class, clazz));
        return obj;

How to update an "array of objects" with Firestore?

If anybody is looking for Java firestore sdk solution to add items in array field:

List<String> list = java.util.Arrays.asList("A", "B");
Object[] fieldsToUpdate = list.toArray();
DocumentReference docRef = getCollection().document("docId");
docRef.update(fieldName, FieldValue.arrayUnion(fieldsToUpdate));

To delete items from array user: FieldValue.arrayRemove()

Reading input files by line using read command in shell scripting skips last line

Below code with Redirected "while-read" loop works fine for me

while read LINE
      let count++
      echo "$count $LINE"

done < $FILENAME

echo -e "\nTotal $count Lines read"

WARNING: UNPROTECTED PRIVATE KEY FILE! when trying to SSH into Amazon EC2 Instance

To fix this,

  1. you’ll need to reset the permissions back to default:

    sudo chmod 600 ~/.ssh/id_rsa
    sudo chmod 600 ~/.ssh/

    If you are getting another error:

    • Are you sure you want to continue connecting (yes/no)? yes
    • Failed to add the host to the list of known hosts (/home/geek/.ssh/known_hosts).
  2. This means that the permissions on that file are also set incorrectly, and can be adjusted with this:

    sudo chmod 644 ~/.ssh/known_hosts
  1. Finally, you may need to adjust the directory permissions as well:

    sudo chmod 755 ~/.ssh

This should get you back up and running.

How to get a complete list of ticker symbols from Yahoo Finance?

I managed to do something similar by using this URL:*

It downloads a complete list of stock symbols using the Yahoo YQL API, including the stock name, stock symbol, and industry ID. What it doesn't seem to have is any sort of stock symbol modifiers. E.g. for Rogers Communications Inc, it only downloads RCI, not RCI-A.TO, RCI-B.TO, etc. I haven't found a source for that information yet - if anyone knows of a way to automate downloading that, I'd like to hear it. Also, it'd be nice to find a way to download some sort of relation between the stock symbol and the exchange it's traded on, since some are traded on multiple exchanges, or maybe I only want to look at stuff on the TSX or something.

How to split one string into multiple variables in bash shell?

If your solution doesn't have to be general, i.e. only needs to work for strings like your example, you could do:

var1=$(echo $STR | cut -f1 -d-)
var2=$(echo $STR | cut -f2 -d-)

I chose cut here because you could simply extend the code for a few more variables...

Converting integer to digit list

By looping it can be done the following way :)

num1= int(input('Enter the number'))
sum1 = num1 #making a alt int to store the value of the orginal so it wont be affected
y = [] #making a list 
while True:
    if(sum1==0):#checking if the number is not zero so it can break if it is
    d = sum1%10 #last number of your integer is saved in d
    sum1 = int(sum1/10) #integer is now with out the last number ie.4320/10 become 432
    y.append(d) # appending the last number in the first place

y.reverse()#as last is in first , reversing the number to orginal form

Answer becomes

Enter the number2342
[2, 3, 4, 2]

C pointers and arrays: [Warning] assignment makes pointer from integer without a cast

What are you doing: (I am using bytes instead of in for better reading)

You start with int *ap and so on, so your (your computers) memory looks like this:

-------------- memory used by some one else --------
000: ?
001: ?
098: ?
099: ?
-------------- your memory  --------
100: something          <- here is *ap
101: 41                 <- here starts a[] 
102: 42
103: 43
104: 44
105: 45
106: something          <- here waits x

lets take a look waht happens when (print short cut for ...print("$d", ...)

print a[0]  -> 41   //no surprise
print a     -> 101  // because a points to the start of the array
print *a    -> 41   // again the first element of array
print a+1   -> guess? 102
print *(a+1)    -> whats behind 102? 42 (we all love this number)

and so on, so a[0] is the same as *a, a[1] = *(a+1), ....

a[n] just reads easier.

now, what happens at line 9?

ap=a[4] // we know a[4]=*(a+4) somehow *105 ==>  45 
// warning! converting int to pointer!
-------------- your memory  --------
100: 45         <- here is *ap now 45

x = *ap;   // wow ap is 45 -> where is 45 pointing to?
-------------- memory used by some one else --------
bang!      // dont touch neighbours garden

So the "warning" is not just a warning it's a severe error.

Sending JSON object to Web API

var model = JSON.stringify({ 
    'ID': 0, 
    'ProductID': $('#ID').val(), 
    'PartNumber': $('#part-number').val(),
    'VendorID': $('#Vendors').val()

    type: "POST",
    dataType: "json",
    contentType: "application/json",
    url: "/api/PartSourceAPI/",
    data: model,
    success: function (data) {
    error: function (error) {
        jsonValue = jQuery.parseJSON(error.responseText);
        jError('An error has occurred while saving the new part source: ' + jsonValue, { TimeShown: 3000 });

var model = JSON.stringify({      'ID': 0,     ...': 5,      'PartNumber': 6,     'VendorID': 7 }) // output is "{"ID":0,"ProductID":5,"PartNumber":6,"VendorID":7}"

your data is something like this "{"model": "ID":0,"ProductID":6,"PartNumber":7,"VendorID":8}}" web api controller cannot bind it to Your model

how to "execute" make file

You don't tend to execute the make file itself, rather you execute make, giving it the make file as an argument:

make -f

If your make file is actually one of the standard names (like makefile or Makefile), you don't even need to specify it. It'll be picked up by default (if you have more than one of these standard names in your build directory, you better look up the make man page to see which takes precedence).

DbEntityValidationException - How can I easily tell what caused the error?

I think "The actual validation errors" may contain sensitive information, and this could be the reason why Microsoft chose to put them in another place (properties). The solution marked here is practical, but it should be taken with caution.

I would prefer to create an extension method. More reasons to this:

  • Keep original stack trace
  • Follow open/closed principle (ie.: I can use different messages for different kind of logs)
  • In production environments there could be other places (ie.: other dbcontext) where a DbEntityValidationException could be thrown.

How do I remove duplicates from a C# array?

If you needed to sort it, then you could implement a sort that also removes duplicates.

Kills two birds with one stone, then.

Virtual/pure virtual explained

  • Virtual functions must have a definition in base class and also in derived class but not necessary, for example ToString() or toString() function is a Virtual so you can provide your own implementation by overriding it in user-defined class(es).

  • Virtual functions are declared and defined in normal class.

  • Pure virtual function must be declared ending with "= 0" and it can only be declared in abstract class.

  • An abstract class having a pure virtual function(s) cannot have a definition(s) of that pure virtual functions, so it implies that implementation must be provided in class(es) that derived from that abstract class.

How to remove an element from an array in Swift

For Swift4:

list = list.filter{$0 != "your Value"}

GridView Hide Column by code

Please use this code. This make invisible column if empty...

    protected void gridview1_DataBound(object sender, EventArgs e)
        Boolean hasData = false;
        for (int col = 0; col < gridview1.HeaderRow.Cells.Count; col++)
            for (int row = 0; row < gridview1.Rows.Count; row++)
                if (!String.IsNullOrEmpty(gridview1.Rows[row].Cells[col].Text)
                    && !String.IsNullOrEmpty(HttpUtility.HtmlDecode(gridview1.Rows[row].Cells[col].Text).Trim()))
                    hasData = true;

            if (!hasData)
                gridview1.HeaderRow.Cells[col].Visible = false;
                for (int hiddenrows = 0; hiddenrows < gridview1.Rows.Count; hiddenrows++)
                    gridview1.Rows[hiddenrows].Cells[col].Visible = false;

            hasData = false;



Saving image from PHP URL

See file()PHP Manual:

$url    = '';
$img    = 'miki.png';
$file   = file($url);
$result = file_put_contents($img, $file)

Measuring Query Performance : "Execution Plan Query Cost" vs "Time Taken"

The profiler trace puts it into perspective.

  • Query A: 1.3 secs CPU, 1.4 secs duration
  • Query B: 2.3 secs CPU, 1.2 secs duration

Query B is using parallelism: CPU > duration eg the query uses 2 CPUs, average 1.15 secs each

Query A is probably not: CPU < duration

This explains cost relative to batch: 17% of the for the simpler, non-parallel query plan.

The optimiser works out that query B is more expensive and will benefit from parallelism, even though it takes extra effort to do so.

Remember though, that query B uses 100% of 2 CPUS (so 50% for 4 CPUs) for one second or so. Query A uses 100% of a single CPU for 1.5 seconds.

The peak for query A is lower, at the expense of increased duration. With one user, who cares? With 100, perhaps it makes a difference...

What does this GCC error "... relocation truncated to fit..." mean?

I ran into the exact same issue. After compiling without the -fexceptions build flag, the file compiled with no issue

Spring Boot: How can I set the logging level with

Existing answers are greats. I just want to share with you a new spring boot feature allowing to group logs and set logging level on the whole group.

Exemple from the docs :

  • Create a logging group, org.apache.coyote, org.apache.tomcat
  • Set the logging level for group

It's nice feature which brings more flexibility.

How do I flush the cin buffer?

I prefer:


There's an example where cin.ignore just doesn't cut it, but I can't think of it at the moment. It was a while ago when I needed to use it (with Mingw).

However, fflush(stdin) is undefined behavior according to the standard. fflush() is only meant for output streams. fflush(stdin) only seems to work as expected on Windows (with GCC and MS compilers at least) as an extension to the C standard.

So, if you use it, your code isn't going to be portable.

See Using fflush(stdin).

Also, see for an alternative.

Convert javascript array to string

not sure if this is what you wanted but

var arr = ["A", "B", "C"];
var arrString = arr.join(", ");

This results in the following output:

A, B, C

What is char ** in C?

It is a pointer to a pointer, so yes, in a way it's a 2D character array. In the same way that a char* could indicate an array of chars, a char** could indicate that it points to and array of char*s.

How to get substring from string in c#?

string text = "Retrieves a substring from this instance. The substring starts at a specified character position. Some other text";

string result = text.Substring(text.IndexOf('.') + 1,text.LastIndexOf('.')-text.IndexOf('.'))

This will cut the part of string which lays between the special characters.

Simpler way to create dictionary of separate variables?

Well, I encountered the very same need a few days ago and had to get a variable's name which was pointing to the object itself.

And why was it so necessary?

In short I was building a plug-in for Maya. The core plug-in was built using C++ but the GUI is drawn through Python(as its not processor intensive). Since I, as yet, don't know how to return multiple values from the plug-in except the default MStatus, therefore to update a dictionary in Python I had to pass the the name of the variable, pointing to the object implementing the GUI and which contained the dictionary itself, to the plug-in and then use the MGlobal::executePythonCommand() to update the dictionary from the global scope of Maya.

To do that what I did was something like:

import time

class foo(bar):

    def __init__(self):
        super(foo, self).__init__()
        self.time = time.time() #almost guaranteed to be unique on a single computer

    def name(self):
        g = globals()
        for x in g:
            if isinstance(g[x], type(self)):
                if g[x].time == self.time:
                    return x
                    #or you could:
                    #return filter(None,[x if g[x].time == self.time else None for x in g if isinstance(g[x], type(self))])
                    #and return all keys pointing to object itself

I know that it is not the perfect solution in in the globals many keys could be pointing to the same object e.g.:

a = foo()
b = a

and that the approach isn't thread-safe. Correct me if I am wrong.

At least this approach solved my problem by getting the name of any variable in the global scope which pointed to the object itself and pass it over to the plug-in, as argument, for it use internally.

I tried this on int (the primitive integer class) but the problem is that these primitive classes don't get bypassed (please correct the technical terminology used if its wrong). You could re-implement int and then do int = foo but a = 3 will never be an object of foo but of the primitive. To overcome that you have to a = foo(3) to get to work.

How many bytes does one Unicode character take?

I know this question is old and already has an accepted answer, but I want to offer a few examples (hoping it'll be useful to someone).

As far as I know old ASCII characters took one byte per character.

Right. Actually, since ASCII is a 7-bit encoding, it supports 128 codes (95 of which are printable), so it only uses half a byte (if that makes any sense).

How many bytes does a Unicode character require?

Unicode just maps characters to codepoints. It doesn't define how to encode them. A text file does not contain Unicode characters, but bytes/octets that may represent Unicode characters.

I assume that one Unicode character can contain every possible character from any language - am I correct?

No. But almost. So basically yes. But still no.

So how many bytes does it need per character?

Same as your 2nd question.

And what do UTF-7, UTF-6, UTF-16 etc mean? Are they some kind Unicode versions?

No, those are encodings. They define how bytes/octets should represent Unicode characters.

A couple of examples. If some of those cannot be displayed in your browser (probably because the font doesn't support them), go to (replace 1F6AA with the codepoint in hex) to see an image.

    • U+0061 LATIN SMALL LETTER A: a
      • Nº: 97
      • UTF-8: 61
      • UTF-16: 00 61
    • U+00A9 COPYRIGHT SIGN: ©
      • Nº: 169
      • UTF-8: C2 A9
      • UTF-16: 00 A9
      • Nº: 174
      • UTF-8: C2 AE
      • UTF-16: 00 AE
      • Nº: 4919
      • UTF-8: E1 8C B7
      • UTF-16: 13 37
    • U+2014 EM DASH:
      • Nº: 8212
      • UTF-8: E2 80 94
      • UTF-16: 20 14
    • U+2030 PER MILLE SIGN:
      • Nº: 8240
      • UTF-8: E2 80 B0
      • UTF-16: 20 30
    • U+20AC EURO SIGN:
      • Nº: 8364
      • UTF-8: E2 82 AC
      • UTF-16: 20 AC
    • U+2122 TRADE MARK SIGN:
      • Nº: 8482
      • UTF-8: E2 84 A2
      • UTF-16: 21 22
    • U+2603 SNOWMAN: ?
      • Nº: 9731
      • UTF-8: E2 98 83
      • UTF-16: 26 03
      • Nº: 9742
      • UTF-8: E2 98 8E
      • UTF-16: 26 0E
      • Nº: 9748
      • UTF-8: E2 98 94
      • UTF-16: 26 14
      • Nº: 9786
      • UTF-8: E2 98 BA
      • UTF-16: 26 3A
    • U+2691 BLACK FLAG: ?
      • Nº: 9873
      • UTF-8: E2 9A 91
      • UTF-16: 26 91
    • U+269B ATOM SYMBOL: ?
      • Nº: 9883
      • UTF-8: E2 9A 9B
      • UTF-16: 26 9B
    • U+2708 AIRPLANE: ?
      • Nº: 9992
      • UTF-8: E2 9C 88
      • UTF-16: 27 08
      • Nº: 10014
      • UTF-8: E2 9C 9E
      • UTF-16: 27 1E
    • U+3020 POSTAL MARK FACE: ?
      • Nº: 12320
      • UTF-8: E3 80 A0
      • UTF-16: 30 20
    • U+8089 CJK UNIFIED IDEOGRAPH-8089: ?
      • Nº: 32905
      • UTF-8: E8 82 89
      • UTF-16: 80 89
    • U+1F4A9 PILE OF POO:
      • Nº: 128169
      • UTF-8: F0 9F 92 A9
      • UTF-16: D8 3D DC A9
    • U+1F680 ROCKET:
      • Nº: 128640
      • UTF-8: F0 9F 9A 80
      • UTF-16: D8 3D DE 80

Okay I'm getting carried away...

Fun facts:

Oracle JDBC intermittent Connection Issue

Disabling SQL Net Banners saved us.

Group By Multiple Columns

Though this question is asking about group by class properties, if you want to group by multiple columns against a ADO object (like a DataTable), you have to assign your "new" items to variables:

EnumerableRowCollection<DataRow> ClientProfiles = CurrentProfiles.AsEnumerable()
                        .Where(x => CheckProfileTypes.Contains(x.Field<object>(ProfileTypeField).ToString()));
// do other stuff, then check for dups...
                    var Dups = ClientProfiles.AsParallel()
                        .GroupBy(x => new { InterfaceID = x.Field<object>(InterfaceField).ToString(), ProfileType = x.Field<object>(ProfileTypeField).ToString() })
                        .Where(z => z.Count() > 1)
                        .Select(z => z);

html script src="" triggering redirection with button

I was having this problem but i found out that it was a permissions problem I changed my permissions to 0744 and now it works. I don't know if this was your problem but it worked for me.

In Python, how do I use urllib to see if a website is 404 or 200?

The getcode() method (Added in python2.6) returns the HTTP status code that was sent with the response, or None if the URL is no HTTP URL.

>>> a=urllib.urlopen('')
>>> a.getcode()
>>> a=urllib.urlopen('')
>>> a.getcode()

Find index of last occurrence of a substring in a string

You can use rfind() or rindex()
Python2 links: rfind() rindex()

>>> s = 'Hello StackOverflow Hi everybody'

>>> print( s.rfind('H') )

>>> print( s.rindex('H') )

>>> print( s.rfind('other') )

>>> print( s.rindex('other') )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

The difference is when the substring is not found, rfind() returns -1 while rindex() raises an exception ValueError (Python2 link: ValueError).

If you do not want to check the rfind() return code -1, you may prefer rindex() that will provide an understandable error message. Else you may search for minutes where the unexpected value -1 is coming from within your code...

Example: Search of last newline character

>>> txt = '''first line
... second line
... third line'''

>>> txt.rfind('\n')

>>> txt.rindex('\n')

How can I configure my makefile for debug and release builds?

If by configure release/build, you mean you only need one config per makefile, then it is simply a matter and decoupling CC and CFLAGS:

CC=g++ -g3 -gdwarf2 $(CFLAGS)

Depending on whether you can use gnu makefile, you can use conditional to make this a bit fancier, and control it from the command line:

DEBUG ?= 1
ifeq ($(DEBUG), 1)

.o: .c
    $(CC) -c $< -o $@ $(CFLAGS)

and then use:

make DEBUG=0
make DEBUG=1

If you need to control both configurations at the same time, I think it is better to have build directories, and one build directory / config.

Laravel check if collection is empty

I prefer


Is more effective and accurate

force line break in html table cell

I suggest you use a wrapper div or paragraph:

<td><p style="width:50%;">Text only allowed to extend 50% of the cell.</p></td>

And you can make a class out of it:

<td class="linebreak"><p>Text only allowed to extend 50% of the cell.</p></td>

td.linebreak p {
    width: 50%;

All of this assuming that you meant 50% as in 50% of the cell.

Chart.js v2 - hiding grid lines

OK, nevermind.. I found the trick:

    scales: {
      yAxes: [
          gridLines: {
                lineWidth: 0

Iterate through a HashMap


for (String key : hashMap.keySet()) {
    System.out.println("Key: " + key + ", Value: " + map.get(key));

How can I test an AngularJS service from the console?

First of all, a modified version of your service.

a )

var app = angular.module('app',[]);

    return {
        f1 : function(world){
            return 'Hello' + world;

This returns an object, nothing to new here.

Now the way to get this from the console is

b )

var $inj = angular.injector(['app']);
var serv = $inj.get('ExampleService');

c )

One of the things you were doing there earlier was to assume that the app.factory returns you the function itself or a new'ed version of it. Which is not the case. In order to get a constructor you would either have to do

        return function(){
            this.f1 = function(world){
                return 'Hello' + world;

This returns an ExampleService constructor which you will next have to do a 'new' on.

Or alternatively,

            this.f1 = function(world){
                return 'Hello' + world;

This returns new ExampleService() on injection.

Laravel Advanced Wheres how to pass variable into function?

You can pass the necessary variables from the parent scope into the closure with the use keyword.

For example:

DB::table('users')->where(function ($query) use ($activated) {
    $query->where('activated', '=', $activated);

More on that here.

EDIT (2019 update):

PHP 7.4 (will be released at November 28, 2019) introduces a shorter variation of the anonymous functions called arrow functions which makes this a bit less verbose.

An example using PHP 7.4 which is functionally nearly equivalent (see the 3rd bullet point below):

DB::table('users')->where(fn($query) => $query->where('activated', '=', $activated))->get();

Differences compared to the regular syntax:

  • fn keyword instead of function.
  • No need to explicitly list all variables which should be captured from the parent scope - this is now done automatically by-value. See the lack of use keyword in the latter example.
  • Arrow functions always return a value. This also means that it's impossible to use void return type when declaring them.
  • The return keyword must be omitted.
  • Arrow functions must have a single expression which is the return statement. Multi-line functions aren't supported at the moment. You can still chain methods though.

scrollIntoView Scrolls just too far

I've got this and it works brilliantly for me:

// add a smooth scroll to element
scroll(el) {
  behavior: 'smooth',
  block: 'start'});

setTimeout(() => {
window.scrollBy(0, -40);
}, 500);}

Hope it helps.

How to set -source 1.7 in Android Studio and Gradle

You can change it in new Android studio version(0.8.X)

FIle-> Other Settings -> Default Settings -> Compiler (Expand it by clicking left arrow) -> Java Compiler -> You can change the Project bytecode version here

enter image description here

How do you synchronise projects to GitHub with Android Studio?

Android Studio 3.0

I love how easy this is in Android Studio.

1. Enter your GitHub login info

In Android Studio go to File > Settings > Version Control > GitHub. Then enter your GitHub username and password. (You only have to do this step once. For future projects you can skip it.)

enter image description here

2. Share your project

With your Android Studio project open, go to VCS > Import into Version Control > Share Project on GitHub.

Then click Share and OK.

enter image description here

That's all!

How to list files in an android directory?

In order to access the files, the permissions must be given in the manifest file.

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Try this:

String path = Environment.getExternalStorageDirectory().toString()+"/Pictures";
Log.d("Files", "Path: " + path);
File directory = new File(path);
File[] files = directory.listFiles();
Log.d("Files", "Size: "+ files.length);
for (int i = 0; i < files.length; i++)
    Log.d("Files", "FileName:" + files[i].getName());

CURL and HTTPS, "Cannot resolve host"

Your getting the error because you're probably doing it on your Local server environment. You need to skip the certificates check when the cURL call is made. For that just add the following options

curl_setopt($c, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($c, CURLOPT_SSL_VERIFYHOST,  0);

How can I extract all values from a dictionary in Python?

Pythonic duck-typing should in principle determine what an object can do, i.e., its properties and methods. By looking at a dictionary object one may try to guess it has at least one of the following: dict.keys() or dict.values() methods. You should try to use this approach for future work with programming languages whose type checking occurs at runtime, especially those with the duck-typing nature.

Spring Boot - inject map from application.yml

Solution for pulling Map using @Value from application.yml property coded as multiline


other-prop: just for demo 

my-map-property-name: "{\
         key1: \"ANY String Value here\", \  
         key2: \"any number of items\" , \ 
         key3: \"Note the Last item does not have comma\" \

other-prop2: just for demo 2 

Here the value for our map property "my-map-property-name" is stored in JSON format inside a string and we have achived multiline using \ at end of line

import org.springframework.beans.factory.annotation.Value;

public class myJavaClass {

private Map<String,String> myMap;

public void someRandomMethod (){
    if(myMap.containsKey("key1")) {
    } }


More explanation

  • \ in yaml it is Used to break string into multiline

  • \" is escape charater for "(quote) in yaml string

  • {key:value} JSON in yaml which will be converted to Map by @Value

  • #{ } it is SpEL expresion and can be used in @Value to convert json int Map or Array / list Reference

Tested in a spring boot project

What is the difference between a mutable and immutable string in C#?

Mutable and immutable are English words meaning "can change" and "cannot change" respectively. The meaning of the words is the same in the IT context; i.e.

  • a mutable string can be changed, and
  • an immutable string cannot be changed.

The meanings of these words are the same in C# / .NET as in other programming languages / environments, though (obviously) the names of the types may differ, as may other details.

For the record:

  • String is the standard C# / .Net immutable string type
  • StringBuilder is the standard C# / .Net mutable string type

To "effect a change" on a string represented as a C# String, you actually create a new String object. The original String is not changed ... because it is unchangeable.

In most cases it is better to use String because it is easier reason about them; e.g. you don't need to consider the possibility that some other thread might "change my string".

However, when you need to construct or modify a string using a sequence of operations, it may be more efficient to use a StringBuilder. An example is when you are concatenating many string fragments to form a large string:

  • If you do this as a sequence of String concatenations, you copy O(N^2) characters, where N is the number of component strings.
  • If use a StringBuilder you only copy O(N) characters.

And finally, for those people who assert that a StringBuilder is not a string because it is not immutable, the Microsoft documentation describes StringBuilder thus:

"Represents a mutable string of characters. This class cannot be inherited."

How to get a time zone from a location using latitude and longitude coordinates?

It's indeed important to recognize that this a more complicated problem than most would suspect. In practice many of us are also willing to accept a working set of code that works for "as many cases as possible", where at least its fatal issues can be identified and minimized collectively. So I post this with all of that and the spirit of the OP in mind. Finally, for practical value to others who are trying to convert GPS to timezone with the end goal of having a location-sensitive time object (and more importantly to help advance the quality of average implementations with time objects that follow from this wiki) here is what I generated in Python (please feel free to edit):

import pytz
from datetime import datetime
from tzwhere import tzwhere

def timezoned_unixtime(latitude, longitude, dt):
    tzw = tzwhere.tzwhere()
    timezone_str = tzw.tzNameAt(latitude, longitude)
    timezone = pytz.timezone(timezone_str)
    timezone_aware_datetime = timezone.localize(dt, is_dst=None)
    unix_time = (timezone_aware_datetime - datetime(1970, 1, 1, tzinfo=pytz.utc)).total_seconds()
    return unix_time

dt = datetime(year=2017, month=1, day=17, hour=12, minute=0, second=0)
print timezoned_unixtime(latitude=40.747854, longitude=-74.004733, dt=dt)

Converting xml to string using C#

There's a much simpler way to convert your XmlDocument to a string; use the OuterXml property. The OuterXml property returns a string version of the xml.

public string GetXMLAsString(XmlDocument myxml)
    return myxml.OuterXml;

How to write a basic swap function in Java

  class Swap2Values{
    public static void main(String[] args){
       int a = 20, b = 10;

       //before swaping
       System.out.print("Before Swapping the values of a and b are: a = "+a+", b = "+b);

       a = a + b;
       b = a - b;
       a = a - b;

       //after swapping
      System.out.print("After Swapping the values of a and b are: a = "+a+", b = "+b);

initializing a boolean array in java

They will be initialized to false by default. In Java arrays are created on heap and every element of the array is given a default value depending on its type. For boolean data type the default value is false.

How to pass arguments to a Button command in Tkinter?

Just to make the answer of Nae a little bit more elaborate, here is a full blown example which includes the possibility to pass a variable to the callback which contains different values for each button:

import tkinter as tk
def callback(text):

top = tk.Tk()
Texts=["text1", "text2", "text3"]

for i, z in enumerate(Texts):
    Buttons.append(tk.Button(top, text=z, command= lambda ztemp=z : callback(ztemp)))
    Buttons[i].pack(side=tk.LEFT, padx=5)


By defining a temporary variable ztemp, the value of that variable gets fixed at the moment when the button is defined.

Batch file to copy files from one folder to another folder

@echo off

rem The * at the end of the destination file is to avoid File/Directory Internal Question.

rem You can do this for each especific file. (Make sure you already have permissions to the path)
xcopy /Y "\\Oldeserver\storage\data\MyFile01.txt" "\\New server\storage\data\MyFile01.txt"*

rem You can use "copy" instead of "xcopy "for this example.

How do I convert an ANSI encoded file to UTF-8 with Notepad++?

If you don't have non-ASCII characters (codepoints 128 and above) in your file, UTF-8 without BOM is the same as ASCII, byte for byte - so Notepad++ will guess wrong.

What you need to do is to specify the character encoding when serving the AJAX response - e.g. with PHP, you'd do this:

header('Content-Type: application/json; charset=utf-8');

The important part is to specify the charset with every JS response - else IE will fall back to user's system default encoding, which is wrong most of the time.

set date in input type date

Jquery version

var currentdate = new Date();

$('#DatePickerInputID').val($.datepicker.formatDate('dd-M-y', currentdate));

How to do case insensitive search in Vim

I prefer to use \c at the end of the search string:


Is object empty?

Underscore and lodash each have a convenient isEmpty() function, if you don't mind adding an extra library.


sqlite database default time value 'now'

It's just a syntax error, you need parenthesis: (DATETIME('now'))

If you look at the documentation, you'll note the parenthesis that is added around the 'expr' option in the syntax.

Maintain image aspect ratio when changing height

This behavior is expected. flex container will stretch all its children by default. Image have no exception. (ie, parent will have align-items: stretch property )

To keep the aspect ratio we've two solutions:

  1. Either replace default align-items: stretch property to align-items: flex-start or align-self: center etc,


  1. Set align property exclusively to the child itself: like, align-self: center or align-self: flex-start etc.

CodeIgniter 500 Internal Server Error

Make sure your root index.php file has the correct permission, its permission must be 0755 or 0644

Labeling file upload button

You get your browser's language for your button. There's no way to change it programmatically.

Why do you create a View in a database?

To Focus on Specific Data Views allow users to focus on specific data that interests them and on the specific tasks for which they are responsible. Unnecessary data can be left out of the view. This also increases the security of the data because users can see only the data that is defined in the view and not the data in the underlying table. For more information about using views for security purposes, see Using Views as Security Mechanisms.

To Simplify Data Manipulation Views can simplify how users manipulate data. You can define frequently used joins, projections, UNION queries, and SELECT queries as views so that users do not have to specify all the conditions and qualifications each time an additional operation is performed on that data. For example, a complex query that is used for reporting purposes and performs subqueries, outer joins, and aggregation to retrieve data from a group of tables can be created as a view. The view simplifies access to the data because the underlying query does not have to be written or submitted each time the report is generated; the view is queried instead. For more information about manipulating data.

You can also create inline user-defined functions that logically operate as parameterized views, or views that have parameters in WHERE-clause search conditions. For more information, see Inline User-defined Functions.

To Customize Data Views allow different users to see data in different ways, even when they are using the same data concurrently. This is particularly advantageous when users with many different interests and skill levels share the same database. For example, a view can be created that retrieves only the data for the customers with whom an account manager deals. The view can determine which data to retrieve based on the login ID of the account manager who uses the view.

To Export and Import Data Views can be used to export data to other applications. For example, you may want to use the stores and sales tables in the pubs database to analyze sales data using Microsoft® Excel. To do this, you can create a view based on the stores and sales tables. You can then use the bcp utility to export the data defined by the view. Data can also be imported into certain views from data files using the bcp utility or BULK INSERT statement providing that rows can be inserted into the view using the INSERT statement. For more information about the restrictions for copying data into views, see INSERT. For more information about using the bcp utility and BULK INSERT statement to copy data to and from a view, see Copying To or From a View.

To Combine Partitioned Data The Transact-SQL UNION set operator can be used within a view to combine the results of two or more queries from separate tables into a single result set. This appears to the user as a single table called a partitioned view. For example, if one table contains sales data for Washington, and another table contains sales data for California, a view could be created from the UNION of those tables. The view represents the sales data for both regions. To use partitioned views, you create several identical tables, specifying a constraint to determine the range of data that can be added to each table. The view is then created using these base tables. When the view is queried, SQL Server automatically determines which tables are affected by the query and references only those tables. For example, if a query specifies that only sales data for the state of Washington is required, SQL Server reads only the table containing the Washington sales data; no other tables are accessed.

Partitioned views can be based on data from multiple heterogeneous sources, such as remote servers, not just tables in the same database. For example, to combine data from different remote servers each of which stores data for a different region of your organization, you can create distributed queries that retrieve data from each data source, and then create a view based on those distributed queries. Any queries read only data from the tables on the remote servers that contains the data requested by the query; the other servers referenced by the distributed queries in the view are not accessed.

When you partition data across multiple tables or multiple servers, queries accessing only a fraction of the data can run faster because there is less data to scan. If the tables are located on different servers, or on a computer with multiple processors, each table involved in the query can also be scanned in parallel, thereby improving query performance. Additionally, maintenance tasks, such as rebuilding indexes or backing up a table, can execute more quickly. By using a partitioned view, the data still appears as a single table and can be queried as such without having to reference the correct underlying table manually.

Partitioned views are updatable if either of these conditions is met: An INSTEAD OF trigger is defined on the view with logic to support INSERT, UPDATE, and DELETE statements.

Both the view and the INSERT, UPDATE, and DELETE statements follow the rules defined for updatable partitioned views. For more information, see Creating a Partitioned View.

Why do we have to override the equals() method in Java?

To answer your question, firstly I would strongly recommend looking at the Documentation.

Without overriding the equals() method, it will act like "==". When you use the "==" operator on objects, it simply checks to see if those pointers refer to the same object. Not if their members contain the same value.

We override to keep our code clean, and abstract the comparison logic from the If statement, into the object. This is considered good practice and takes advantage of Java's heavily Object Oriented Approach.

What is the difference between a deep copy and a shallow copy?

A shallow copy constructs a new compound object and insert its references into it to the original object.

Unlike shallow copy, deepcopy constructs new compound object and also inserts copies of the original objects of original compound object.

Lets take an example.

import copy
x =[1,[2]]
z= copy.deepcopy(x)
print(y is z)

Above code prints FALSE.

Let see how.

Original compound object x=[1,[2]] (called as compound because it has object inside object (Inception))

enter image description here

as you can see in the image, there is a list inside list.

Then we create a shallow copy of it using y = copy.copy(x). What python does here is, it will create a new compound object but objects inside them are pointing to the orignal objects.

enter image description here

In the image it has created a new copy for outer list. but the inner list remains same as the original one.

Now we create deepcopy of it using z = copy.deepcopy(x). what python does here is, it will create new object for outer list as well as inner list. as shown in the image below (red highlighted).

enter image description here

At the end code prints False, as y and z are not same objects.


Why is NULL undeclared?

NULL isn't a native part of the core C++ language, but it is part of the standard library. You need to include one of the standard header files that include its definition. #include <cstddef> or #include <stddef.h> should be sufficient.

The definition of NULL is guaranteed to be available if you include cstddef or stddef.h. It's not guaranteed, but you are very likely to get its definition included if you include many of the other standard headers instead.

multiple ways of calling parent method in php

There are three scenarios (that I can think of) where you would call a method in a subclass where the method exits in the parent class:

  1. Method is not overwritten by subclass, only exists in parent.

    This is the same as your example, and generally it's better to use $this -> get_species(); You are right that in this case the two are effectively the same, but the method has been inherited by the subclass, so there is no reason to differentiate. By using $this you stay consistent between inherited methods and locally declared methods.

  2. Method is overwritten by the subclass and has totally unique logic from the parent.

    In this case, you would obviously want to use $this -> get_species(); because you don't want the parent's version of the method executed. Again, by consistently using $this, you don't need to worry about the distinction between this case and the first.

  3. Method extends parent class, adding on to what the parent method achieves.

    In this case, you still want to use `$this -> get_species(); when calling the method from other methods of the subclass. The one place you will call the parent method would be from the method that is overwriting the parent method. Example:

    abstract class Animal {
        function get_species() {
            echo "I am an animal.";
     class Dog extends Animal {
         function __construct(){
         function get_species(){
             echo "More specifically, I am a dog.";

The only scenario I can imagine where you would need to call the parent method directly outside of the overriding method would be if they did two different things and you knew you needed the parent's version of the method, not the local. This shouldn't be the case, but if it did present itself, the clean way to approach this would be to create a new method with a name like get_parentSpecies() where all it does is call the parent method:

function get_parentSpecies(){


Again, this keeps everything nice and consistent, allowing for changes/modifications to the local method rather than relying on the parent method.

Removing elements from an array in C

Interestingly array is randomly accessible by the index. And removing randomly an element may impact the indexes of other elements as well.

    int remove_element(int*from, int total, int index) {
            if((total - index - 1) > 0) {
                      memmove(from+i, from+i+1, sizeof(int)*(total-index-1));
            return total-1; // return the new array size

Note that memcpy will not work in this case because of the overlapping memory.

One of the efficient way (better than memory move) to remove one random element is swapping with the last element.

    int remove_element(int*from, int total, int index) {
            if(index != (total-1))
                    from[index] = from[total-1];
            return total; // **DO NOT DECREASE** the total here

But the order is changed after the removal.

Again if the removal is done in loop operation then the reordering may impact processing. Memory move is one expensive alternative to keep the order while removing an array element. Another of the way to keep the order while in a loop is to defer the removal. It can be done by validity array of the same size.

    int remove_element(int*from, int total, int*is_valid, int index) {
            is_valid[index] = 0;
            return total-1; // return the number of elements

It will create a sparse array. Finally, the sparse array can be made compact(that contains no two valid elements that contain invalid element between them) by doing some reordering.

    int sparse_to_compact(int*arr, int total, int*is_valid) {
            int i = 0;
            int last = total - 1;
            // trim the last invalid elements
            for(; last >= 0 && !is_valid[last]; last--); // trim invalid elements from last

            // now we keep swapping the invalid with last valid element
            for(i=0; i < last; i++) {
                    arr[i] = arr[last]; // swap invalid with the last valid
                    for(; last >= 0 && !is_valid[last]; last--); // trim invalid elements
            return last+1; // return the compact length of the array

Get source JARs from Maven repository

In Eclipse

  1. Right click on the pom.xml
  2. Select Run As -> Maven generate-sources
    it will generate the source by default in .m2 folder


Maven should be configured with Eclipse.

How to create and add users to a group in Jenkins for authentication?

You could use Role Strategy plugin for that purpose. It works like a charm, just setup some roles and assign them. Even on project-specific level.

How to increase request timeout in IIS?

In IIS >= 7, a <webLimits> section has replaced ConnectionTimeout, HeaderWaitTimeout, MaxGlobalBandwidth, and MinFileBytesPerSec IIS 6 metabase settings.

Example Configuration:

      <webLimits connectionTimeout="00:01:00"

For reference: more information regarding these settings in IIS can be found here. Also, I was unable to add this section to the web.config via the IIS manager's "configuration editor", though it did show up once I added it and searched the configuration.

How to convert Moment.js date to users local timezone?

Use utcOffset function.

var testDateUtc = moment.utc("2015-01-30 10:00:00");
var localDate = moment(testDateUtc).utcOffset(10 * 60); //set timezone offset in minutes
console.log(localDate.format()); //2015-01-30T20:00:00+10:00

Angular 4 setting selected option in Dropdown

If you want to select a value as default, in your form builder give it a value :

this.myForm ={
    mySelect: [this.options[0].key, [/* Validators here */]]

Now in your HTML :

<form [formGroup]="myForm">
    <select [formControlName]="mySelect">
        <option *ngFor="let opt of options" [value]="opt.key">ANY TEXT YOU WANT HERE</option>

What my code does is giving your select a value, that is equal to the first value of your options list. This is how you select an option as default in Angular, selected is useless.

Spring Could not Resolve placeholder

enter image description hereI know It is an old message , but i want to add my case.

If you use more than one profile(dev,test,prod...), check your execute profile.

To switch from vertical split to horizontal split fast in Vim

Vim mailing list says (re-formatted for better readability):

To change two vertically split windows to horizonally split

Ctrl-w t Ctrl-w K

Horizontally to vertically:

Ctrl-w t Ctrl-w H


Ctrl-w t makes the first (topleft) window current

Ctrl-w K moves the current window to full-width at the very top

Ctrl-w H moves the current window to full-height at far left

Note that the t is lowercase, and the K and H are uppercase.

Also, with only two windows, it seems like you can drop the Ctrl-w t part because if you're already in one of only two windows, what's the point of making it current?

MySQL combine two columns and add into a new column

Are you sure you want to do this? In essence, you're duplicating the data that is in the three original columns. From that point on, you'll need to make sure that the data in the combined field matches the data in the first three columns. This is more overhead for your application, and other processes that update the system will need to understand the relationship.

If you need the data, why not select in when you need it? The SQL for selecting what would be in that field would be:

SELECT CONCAT(zipcode, ' - ', city, ', ', state) FROM Table;

This way, if the data in the fields changes, you don't have to update your combined field.

Recommended way to save uploaded files in a servlet application

I post my final way of doing it based on the accepted answer:

public final class DataCollectionServlet extends Controller {

    private static final String UPLOAD_LOCATION_PROPERTY_KEY="upload.location";
    private String uploadsDirName;

    public void init() throws ServletException {
        uploadsDirName = property(UPLOAD_LOCATION_PROPERTY_KEY);

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // ...

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        Collection<Part> parts = req.getParts();
        for (Part part : parts) {
            File save = new File(uploadsDirName, getFilename(part) + "_"
                + System.currentTimeMillis());
            final String absolutePath = save.getAbsolutePath();
            sc.getRequestDispatcher(DATA_COLLECTION_JSP).forward(req, resp);

    // helpers
    private static String getFilename(Part part) {
        // courtesy of BalusC :
        for (String cd : part.getHeader("content-disposition").split(";")) {
            if (cd.trim().startsWith("filename")) {
                String filename = cd.substring(cd.indexOf('=') + 1).trim()
                        .replace("\"", "");
                return filename.substring(filename.lastIndexOf('/') + 1)
                        .substring(filename.lastIndexOf('\\') + 1); // MSIE fix.
        return null;

where :

class Controller extends HttpServlet {

    static final String DATA_COLLECTION_JSP="/WEB-INF/jsp/data_collection.jsp";
    static ServletContext sc;
    Logger log;
    // private
    // "/WEB-INF/" also works...
    private static final String PROPERTIES_PATH = "WEB-INF/";
    private Properties properties;

    public void init() throws ServletException {
        // synchronize !
        if (sc == null) sc = getServletContext();
        log = LoggerFactory.getLogger(this.getClass());
        try {
        } catch (IOException e) {
            throw new RuntimeException("Can't load properties file", e);

    private void loadProperties() throws IOException {
        try(InputStream is= sc.getResourceAsStream(PROPERTIES_PATH)) {
                if (is == null)
                    throw new RuntimeException("Can't locate properties file");
                properties = new Properties();

    String property(final String key) {
        return properties.getProperty(key);

and the /WEB-INF/ :


HTH and if you find a bug let me know

JavaScript open in a new window, not tab

I just tried this with IE (11) and Chrome (54.0.2794.1 canary SyzyASan):, "_blank", "x=y")

... and it opened in a new window.

Which means that Clint pachl had it right when he said that providing any one parameter will cause the new window to open.

-- and apparently it doesn't have to be a legitimate parameter!

(YMMV - as I said, I only tested it in two places...and the next upgrade might invalidate the results, any way)

ETA: I just noticed, though - in IE, the window has no decorations.

Writing to a new file if it doesn't exist, and appending to a file if it does

Just open it in 'a' mode:

a   Open for writing. The file is created if it does not exist. The stream is positioned at the end of the file.

with open(filename, 'a') as f:

To see whether you're writing to a new file, check the stream position. If it's zero, either the file was empty or it is a new file.

with open('somefile.txt', 'a') as f:
    if f.tell() == 0:
        print('a new file or the file was empty')
        f.write('The header\n')
        print('file existed, appending')
    f.write('Some data\n')

If you're still using Python 2, to work around the bug, either add, os.SEEK_END) right after open or use instead.

`&mdash;` or `&#8212;` is there any difference in HTML output?

They are exactly the same character. See:

Barring browser bugs they will display the same in all cases, so the only difference would be concerning code readability, which would point to &mdash;.

Or, if you are using UTF-8 as a charset in your HTML document, you could enter the character directly. That would also display exactly the same.

JPA Native Query select and cast object

The accepted answer is incorrect.

createNativeQuery will always return a Query:

public Query createNativeQuery(String sqlString, Class resultClass);

Calling getResultList on a Query returns List:

List getResultList()

When assigning (or casting) to List<MyEntity>, an unchecked assignment warning is produced.

Whereas, createQuery will return a TypedQuery:

public <T> TypedQuery<T> createQuery(String qlString, Class<T> resultClass);

Calling getResultList on a TypedQuery returns List<X>.

List<X> getResultList();

This is properly typed and will not give a warning.

With createNativeQuery, using ObjectMapper seems to be the only way to get rid of the warning. Personally, I choose to suppress the warning, as I see this as a deficiency in the library and not something I should have to worry about.

java.lang.NoClassDefFoundError: org.slf4j.LoggerFactory

I also had the similar problem. I had a maven project and was testing rabbitmq. Firstly it showed me the similar error then I added all the SLF4J dependencies in the maven project and then error changed to "Maven SLF4J: Class path contains multiple SLF4J bindings". Here is the complete list of dependencies from pom.xlm


It worked finally.

Laravel Eloquent groupBy() AND also return count of each group

Try with this

  ->havingRaw('count > 1 ')
  ->orHavingRaw('brand LIKE ?',array("%$keyword%"))

How to get and set the current web page scroll position?

The currently accepted answer is incorrect - document.documentElement.scrollTop always returns 0 on Chrome. This is because WebKit uses body for keeping track of scrolling, whereas Firefox and IE use html.

To get the current position, you want:

document.documentElement.scrollTop || document.body.scrollTop

You can set the current position to 1000px down the page like so:

document.documentElement.scrollTop = document.body.scrollTop = 1000;

Or, using jQuery (animate it while you're at it!):

$("html, body").animate({ scrollTop: "1000px" });

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.

One-liner if statements, how to convert this if-else-statement

return (expression) ? value1 : value2;

If value1 and value2 are actually true and false like in your example, you may as well just

return expression;

Change project name on Android Studio

What works for me is,

Go To Build.gradle Change ApplicationId & sync project.

Right click on your project > Rename > Rename Package.

Run your app and boom.

Hope this works as did for me

Tomcat in Intellij Idea Community Edition

If you are using maven, you can use this command mvn tomcat:run, but first you add in your pom.xml this structure into build tag, just like this:


Is there a way to get the source code from an APK file?

There is also a new application on the Play Store with which it is possible to decompile an apk (system applications too) and view the source code right on your smartphone. It saves the files to your SD card so you can view it on your computer too. It does not require root or something else.

Just install and have fun. I think this is the easiest way to decompile an app.

Random number generator only generating one random number

Every time you execute

Random random = new Random (15);

It does not matter if you execute it millions of times, you will always use the same seed.

If you use

Random random = new Random ();

You get different random number sequence, if a hacker guesses the seed and your algorithm is related to the security of your system - your algorithm is broken. I you execute mult. In this constructor the seed is specified by the system clock and if several instances are created in a very short period of time (milliseconds) it is possible that they may have the same seed.

If you need safe random numbers you must use the class


public static int Next(int min, int max)
    if(min >= max)
        throw new ArgumentException("Min value is greater or equals than Max value.");
    byte[] intBytes = new byte[4];
    using(RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
    return  min +  Math.Abs(BitConverter.ToInt32(intBytes, 0)) % (max - min + 1);


int randomNumber = Next(1,100);

How correctly produce JSON by RESTful web service?

@Path ("Employee")
public JSONObject postEmployee(JSONObject jsonObject)throws Exception{
    return jsonObject;

Is there any option to limit mongodb memory usage?

This can be done with cgroups, by combining knowledge from these two articles:

You can find here a small shell script which will create config and init files for Ubuntu 14.04:

Just like that:

sudo bash -c 'curl -o- | bash'

How to check the multiple permission at single request in Android M?

For Asking Multiple Permission At Once You Can Use this Method link

compile 'com.kishan.askpermission:askpermission:1.0.3'

If you got conflicting in support library then

compile('com.kishan.askpermission:askpermission:1.0.3', {
    exclude group: ''

Now ask for Permission

new AskPermission.Builder(this)
    .setPermissions(Manifest.permission.READ_CONTACTS, Manifest.permission.WRITE_EXTERNAL_STORAGE)
    .setCallback(/* PermissionCallback */)
    .setErrorCallback(/* ErrorCallback */)
    .request(/* Request Code */);

permission granted callback

  public void onPermissionsGranted(int requestCode) {
// your code  }

permission denied callback

 public void onPermissionsDenied(int requestCode) {
// your code} 


public void onShowRationalDialog(PermissionInterface permissionInterface, int requestCode) {
// Alert user by Dialog or any other layout that you want.
// When user press OK you must need to call below method.


public void onShowSettings(PermissionInterface permissionInterface, int requestCode) {
// Alert user by Dialog or any other layout that you want.
// When user press OK you must need to call below method.
// It will open setting screen.


Installing Bootstrap 3 on Rails App

Twitter now has a sass-ready version of bootstrap with gem included, so it is easier than ever to add it to Rails.

Simply add to your gemfile the following:

gem 'sass-rails', '>= 3.2' # sass-rails needs to be higher than 3.2
gem 'bootstrap-sass', '~> 3.1.1'

bundle install and restart your server to make the files available through the pipeline.

There is also support for compass and sass-only:

Form content type for a json HTTP POST?

It looks like people answered the first part of your question (use application/json).

For the second part: It is perfectly legal to send query parameters in a HTTP POST Request.


POST /members?id=1234 HTTP/1.1
Content-Type: application/json

{"email":"[email protected]"}

Query parameters are commonly used in a POST request to refer to an existing resource. The above example would update the email address of an existing member with the id of 1234.

jQuery select change event get selected option

$('select').on('change', function (e) {
    var optionSelected = $("option:selected", this);
    var valueSelected = this.value;

Using Pairs or 2-tuples in Java

Though the article is pretty old now, and though I understand that I'm not really very helpful, I think the work done here:, would have been nice in mainstream Java.

You can do things like:

int a;
char b;
float c;
[a,b,c] = [3,'a',2.33];


[int,int,char] x = [1,2,'a'];


public [int,boolean] Find(int i)
  int idx = FindInArray(A,i);
  return [idx,idx>=0];

[idx, found] = Find(7);

Here tuples are:

  • Defined as primitive types - no templates/generics
  • Stack-allocated if declared locally
  • Assigned using pattern-matching

This approach increases

  • Performance
  • Readability
  • Expressiveness

Include an SVG (hosted on GitHub) in MarkDown

Update 2020: how they made it work while avoiding XSS attacks

GitHub appears to use two security approaches, this is a good article: see also:

Update 2017

A GitHub dev is currently looking into this:

Update 2014-12: GitHub now renders SVG on blob show, so I don't see any reason why not to render on README renderings:

Also note that that SVG does have an XSS attempt but it does not run:

The billion laugh SVG does make Firefox 44 Freeze, but Chromium 48 is OK:

Petah mentioned that blobs are fine because the SVG is inside an iframe.

Possible rationale for GitHub not serving SVG images

The following questions asks about the risks of SVG in general:

How to execute an Oracle stored procedure via a database link

for me, this worked

exec utl_mail.send@myotherdb(
  sender => '[email protected]',recipients => '[email protected], 
  cc => null, subject => 'my subject', message => 'my message'

Match multiline text using regular expression

This has nothing to do with the MULTILINE flag; what you're seeing is the difference between the find() and matches() methods. find() succeeds if a match can be found anywhere in the target string, while matches() expects the regex to match the entire string.

Pattern p = Pattern.compile("xyz");

Matcher m = p.matcher("123xyzabc");
System.out.println(m.find());    // true
System.out.println(m.matches()); // false

Matcher m = p.matcher("xyz");
System.out.println(m.matches()); // true

Furthermore, MULTILINE doesn't mean what you think it does. Many people seem to jump to the conclusion that you have to use that flag if your target string contains newlines--that is, if it contains multiple logical lines. I've seen several answers here on SO to that effect, but in fact, all that flag does is change the behavior of the anchors, ^ and $.

Normally ^ matches the very beginning of the target string, and $ matches the very end (or before a newline at the end, but we'll leave that aside for now). But if the string contains newlines, you can choose for ^ and $ to match at the start and end of any logical line, not just the start and end of the whole string, by setting the MULTILINE flag.

So forget about what MULTILINE means and just remember what it does: changes the behavior of the ^ and $ anchors. DOTALL mode was originally called "single-line" (and still is in some flavors, including Perl and .NET), and it has always caused similar confusion. We're fortunate that the Java devs went with the more descriptive name in that case, but there was no reasonable alternative for "multiline" mode.

In Perl, where all this madness started, they've admitted their mistake and gotten rid of both "multiline" and "single-line" modes in Perl 6 regexes. In another twenty years, maybe the rest of the world will have followed suit.

Disable button in WPF?

I know this isn't as elegant as the other posts, but it's a more straightforward xaml/codebehind example of how to accomplish the same thing.


<StackPanel Orientation="Horizontal">
   <TextBox Name="TextBox01" VerticalAlignment="Top" HorizontalAlignment="Left" Width="70" />
   <Button Name="Button01" VerticalAlignment="Top" HorizontalAlignment="Left" Margin="10,0,0,0" />


Private Sub Window1_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded

        Button01.IsEnabled = False
        Button01.Content = "I am Disabled"

End Sub

Private Sub TextBox01_TextChanged(ByVal sender As Object, ByVal e As System.Windows.Controls.TextChangedEventArgs) Handles TextBox01.TextChanged

        If TextBox01.Text.Trim.Length > 0 Then
            Button01.IsEnabled = True
            Button01.Content = "I am Enabled"
            Button01.IsEnabled = False
            Button01.Content = "I am Disabled"
        End If

End Sub

HSL to RGB color conversion

Here is the modified javascript function, it outputs Hue in set 0-360 degrees.

function rgbToHsl(r, g, b) {
      r /= 255, g /= 255, b /= 255;
      var max = Math.max(r, g, b), min = Math.min(r, g, b);
      var h, s, l = (max + min) / 2;

      if(max == min){
          h = s = 0; // achromatic
      } else {
          var d = max - min;
          s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
              case r: h = (g - b) / d ; break;
              case g: h = 2 + ( (b - r) / d); break;
              case b: h = 4 + ( (r - g) / d); break;
          if (h < 0) h +=360;
     return([h, s, l]);


This one disables all bogus verbs and only allows GET and POST

      <verbs allowUnlisted="false">
    <add verb="GET" allowed="true"/>
    <add verb="POST" allowed="true"/>

Why can't Python import Image from PIL?

The current free version is PIL 1.1.7. This release supports Python 1.5.2 and newer, including 2.5 and 2.6. A version for 3.X will be released later.

Python Imaging Library (PIL)

Your python version is 3.4.1, PIL do not support!

Print the data in ResultSet along with column names

For those who wanted more better version of the resultset printing as util class This was really helpful for printing resultset and does many things from a single util... thanks to Hami Torun!

In this class printResultSet uses ResultSetMetaData in a generic way have a look at it..

import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.StringJoiner;

public final class DBTablePrinter {

     * Column type category for CHAR, VARCHAR
     * and similar text columns.
    public static final int CATEGORY_STRING = 1;
     * Column type category for TINYINT, SMALLINT,
     * INT and BIGINT columns.
    public static final int CATEGORY_INTEGER = 2;
     * Column type category for REAL, DOUBLE,
     * and DECIMAL columns.
    public static final int CATEGORY_DOUBLE = 3;
     * Column type category for date and time related columns like
    public static final int CATEGORY_DATETIME = 4;
     * Column type category for BOOLEAN columns.
    public static final int CATEGORY_BOOLEAN = 5;
     * Column type category for types for which the type name
     * will be printed instead of the content, like BLOB,
     * BINARY, ARRAY etc.
    public static final int CATEGORY_OTHER = 0;
     * Default maximum number of rows to query and print.
    private static final int DEFAULT_MAX_ROWS = 10;
     * Default maximum width for text columns
     * (like a VARCHAR) column.
    private static final int DEFAULT_MAX_TEXT_COL_WIDTH = 150;

     * Overloaded method that prints rows from table tableName
     * to standard out using the given database connection
     * conn. Total number of rows will be limited to
     * {@link #DEFAULT_MAX_ROWS} and
     * {@link #DEFAULT_MAX_TEXT_COL_WIDTH} will be used to limit
     * the width of text columns (like a VARCHAR column).
     * @param conn      Database connection object (java.sql.Connection)
     * @param tableName Name of the database table
    public static void printTable(Connection conn, String tableName) {
        printTable(conn, tableName, DEFAULT_MAX_ROWS, DEFAULT_MAX_TEXT_COL_WIDTH);

     * Overloaded method that prints rows from table tableName
     * to standard out using the given database connection
     * conn. Total number of rows will be limited to
     * maxRows and
     * {@link #DEFAULT_MAX_TEXT_COL_WIDTH} will be used to limit
     * the width of text columns (like a VARCHAR column).
     * @param conn      Database connection object (java.sql.Connection)
     * @param tableName Name of the database table
     * @param maxRows   Number of max. rows to query and print
    public static void printTable(Connection conn, String tableName, int maxRows) {
        printTable(conn, tableName, maxRows, DEFAULT_MAX_TEXT_COL_WIDTH);

     * Overloaded method that prints rows from table tableName
     * to standard out using the given database connection
     * conn. Total number of rows will be limited to
     * maxRows and
     * maxStringColWidth will be used to limit
     * the width of text columns (like a VARCHAR column).
     * @param conn              Database connection object (java.sql.Connection)
     * @param tableName         Name of the database table
     * @param maxRows           Number of max. rows to query and print
     * @param maxStringColWidth Max. width of text columns
    public static void printTable(Connection conn, String tableName, int maxRows, int maxStringColWidth) {
        if (conn == null) {
            System.err.println("DBTablePrinter Error: No connection to database (Connection is null)!");
        if (tableName == null) {
            System.err.println("DBTablePrinter Error: No table name (tableName is null)!");
        if (tableName.length() == 0) {
            System.err.println("DBTablePrinter Error: Empty table name!");
        if (maxRows 
     * ResultSet to standard out using {@link #DEFAULT_MAX_TEXT_COL_WIDTH}
     * to limit the width of text columns.
     * @param rs The ResultSet to print
    public static void printResultSet(ResultSet rs) {
        printResultSet(rs, DEFAULT_MAX_TEXT_COL_WIDTH);

     * Overloaded method to print rows of a 
     * ResultSet to standard out using maxStringColWidth
     * to limit the width of text columns.
     * @param rs                The ResultSet to print
     * @param maxStringColWidth Max. width of text columns
    public static void printResultSet(ResultSet rs, int maxStringColWidth) {
        try {
            if (rs == null) {
                System.err.println("DBTablePrinter Error: Result set is null!");
            if (rs.isClosed()) {
                System.err.println("DBTablePrinter Error: Result Set is closed!");
            if (maxStringColWidth  columns = new ArrayList(columnCount);

            // List of table names. Can be more than one if it is a joined
            // table query
            List tableNames = new ArrayList(columnCount);

            // Get the columns and their meta data.
            // NOTE: columnIndex for rsmd.getXXX methods STARTS AT 1 NOT 0
            for (int i = 1; i  maxStringColWidth) {
                                value = value.substring(0, maxStringColWidth - 3) + "...";

                    // Adjust the column width
                    c.setWidth(value.length() > c.getWidth() ? value.length() : c.getWidth());
                } // END of for loop columnCount

            } // END of while (

            At this point we have gone through meta data, get the
            columns and created all Column objects, iterated over the
            ResultSet rows, populated the column values and adjusted
            the column widths.
            We cannot start printing just yet because we have to prepare
            a row separator String.

            // For the fun of it, I will use StringBuilder
            StringBuilder strToPrint = new StringBuilder();
            StringBuilder rowSeparator = new StringBuilder();

            Prepare column labels to print as well as the row separator.
            It should look something like this:
            +--------+------------+------------+-----------+  (row separator)
            | EMP_NO | BIRTH_DATE | FIRST_NAME | LAST_NAME |  (labels row)
            +--------+------------+------------+-----------+  (row separator)

            // Iterate over columns
            for (Column c : columns) {
                int width = c.getWidth();

                // Center the column label
                String toPrint;
                String name = c.getLabel();
                int diff = width - name.length();

                if ((diff % 2) == 1) {
                    // diff is not divisible by 2, add 1 to width (and diff)
                    // so that we can have equal padding to the left and right
                    // of the column label.

                int paddingSize = diff / 2; // InteliJ says casting to int is redundant.

                // Cool String repeater code thanks to user102008 at

                String padding = new String(new char[paddingSize]).replace("\0", " ");

                toPrint = "| " + padding + name + padding + " ";
                // END centering the column label


                rowSeparator.append(new String(new char[width + 2]).replace("\0", "-"));

            String lineSeparator = System.getProperty("line.separator");

            // Is this really necessary ??
            lineSeparator = lineSeparator == null ? "\n" : lineSeparator;


            strToPrint.insert(0, rowSeparator);

            StringJoiner sj = new StringJoiner(", ");
            for (String name : tableNames) {

            String info = "Printing " + rowCount;
            info += rowCount > 1 ? " rows from " : " row from ";
            info += tableNames.size() > 1 ? "tables " : "table ";
            info += sj.toString();


            // Print out the formatted column labels

            String format;

            // Print out the rows
            for (int i = 0; i 
     * Integers should not be truncated so column widths should
     * be adjusted without a column width limit. Text columns should be
     * left justified and can be truncated to a max. column width etc...


* See also: * java.sql.Types * * @param type Generic SQL type * @return The category this type belongs to */ private static int whichCategory(int type) { switch (type) { case Types.BIGINT: case Types.TINYINT: case Types.SMALLINT: case Types.INTEGER: return CATEGORY_INTEGER; case Types.REAL: case Types.DOUBLE: case Types.DECIMAL: return CATEGORY_DOUBLE; case Types.DATE: case Types.TIME: case Types.TIME_WITH_TIMEZONE: case Types.TIMESTAMP: case Types.TIMESTAMP_WITH_TIMEZONE: return CATEGORY_DATETIME; case Types.BOOLEAN: return CATEGORY_BOOLEAN; case Types.VARCHAR: case Types.NVARCHAR: case Types.LONGVARCHAR: case Types.LONGNVARCHAR: case Types.CHAR: case Types.NCHAR: return CATEGORY_STRING; default: return CATEGORY_OTHER; } } /** * Represents a database table column. */ private static class Column { /** * Column label. */ private String label; /** * Generic SQL type of the column as defined in * * java.sql.Types * . */ private int type; /** * Generic SQL type name of the column as defined in * * java.sql.Types * . */ private String typeName; /** * Width of the column that will be adjusted according to column label * and values to be printed. */ private int width = 0; /** * Column values from each row of a ResultSet. */ private List values = new ArrayList(); /** * Flag for text justification using String.format. * Empty string ("") to justify right, * dash (-) to justify left. * * @see #justifyLeft() */ private String justifyFlag = ""; /** * Column type category. The columns will be categorised according * to their column types and specific needs to print them correctly. */ private int typeCategory = 0; /** * Constructs a new Column with a column label, * generic SQL type and type name (as defined in * * java.sql.Types * ) * * @param label Column label or name * @param type Generic SQL type * @param typeName Generic SQL type name */ public Column(String label, int type, String typeName) { this.label = label; this.type = type; this.typeName = typeName; } /** * Returns the column label * * @return Column label */ public String getLabel() { return label; } /** * Returns the generic SQL type of the column * * @return Generic SQL type */ public int getType() { return type; } /** * Returns the generic SQL type name of the column * * @return Generic SQL type name */ public String getTypeName() { return typeName; } /** * Returns the width of the column * * @return Column width */ public int getWidth() { return width; } /** * Sets the width of the column to width * * @param width Width of the column */ public void setWidth(int width) { this.width = width; } /** * Adds a String representation (value) * of a value to this column object's {@link #values} list. * These values will come from each row of a * * ResultSet * of a database query. * * @param value The column value to add to {@link #values} */ public void addValue(String value) { values.add(value); } /** * Returns the column value at row index i. * Note that the index starts at 0 so that getValue(0) * will get the value for this column from the first row * of a * ResultSet. * * @param i The index of the column value to get * @return The String representation of the value */ public String getValue(int i) { return values.get(i); } /** * Returns the value of the {@link #justifyFlag}. The column * values will be printed using String.format and * this flag will be used to right or left justify the text. * * @return The {@link #justifyFlag} of this column * @see #justifyLeft() */ public String getJustifyFlag() { return justifyFlag; } /** * Sets {@link #justifyFlag} to "-" so that * the column value will be left justified when printed with * String.format. Typically numbers will be right * justified and text will be left justified. */ public void justifyLeft() { this.justifyFlag = "-"; } /** * Returns the generic SQL type category of the column * * @return The {@link #typeCategory} of the column */ public int getTypeCategory() { return typeCategory; } /** * Sets the {@link #typeCategory} of the column * * @param typeCategory The type category */ public void setTypeCategory(int typeCategory) { this.typeCategory = typeCategory; } } }

This is the scala version of doing this... which will print column names and data as well in a generic way...

def printQuery(res: ResultSet): Unit = {
    val rsmd = res.getMetaData
    val columnCount = rsmd.getColumnCount
    var rowCnt = 0
    val s = StringBuilder.newBuilder
    while ( {

      if (rowCnt == 0) {
        s.append("| ")
        for (i <- 1 to columnCount) {
          val name = rsmd.getColumnName(i)
          s.append("| ")
      rowCnt += 1
      s.append("| ")
      for (i <- 1 to columnCount) {
        if (i > 1)
          s.append(" | ")
      s.append(" |")
    System.out.println(s"TOTAL: $rowCnt rows")

Why is there no Constant feature in Java?

This is a bit of an old question, but I thought I would contribute my 2 cents anyway since this thread came up in conversation today.

This doesn't exactly answer why is there no const? but how to make your classes immutable. (Unfortunately I have not enough reputation yet to post as a comment to the accepted answer)

The way to guarantee immutability on an object is to design your classes more carefully to be immutable. This requires a bit more care than a mutable class.

This goes back to Josh Bloch's Effective Java Item 15 - Minimize Mutability. If you haven't read the book, pick up a copy and read it over a few times I guarantee it will up your figurative "java game".

In item 15 Bloch suggest that you should limit the mutability of classes to ensure the object's state.

To quote the book directly:

An immutable class is simply a class whose instances cannot be modified. All of the information contained in each instance is provided when it is created and is fixed for the lifetime of the object. The Java platform libraries contain many immutable classes, including String, the boxed primitive classes, and BigInte- ger and BigDecimal. There are many good reasons for this: Immutable classes are easier to design, implement, and use than mutable classes. They are less prone to error and are more secure.

Bloch then describes how to make your classes immutable, by following 5 simple rules:

  1. Don’t provide any methods that modify the object’s state (i.e., setters, aka mutators)
  2. Ensure that the class can’t be extended (this means declaring the class itself as final).
  3. Make all fields final.
  4. Make all fields private.
  5. Ensure exclusive access to any mutable components. (by making defensive copies of the objects)

For more details I highly recommend picking up a copy of the book.

How to determine when a Git branch was created?

This commands shows the created date of branch dev from main

$git reflog show --date=iso dev
$7a2b33d dev@{2012-11-23 13:20:28 -2100}: branch: Created from main

How to set up Spark on Windows?

Here's the fixes to get it to run in Windows without rebuilding everything - such as if you do not have a recent version of MS-VS. (You will need a Win32 C++ compiler, but you can install MS VS Community Edition free.)

I've tried this with Spark 1.2.2 and mahout 0.10.2 as well as with the latest versions in November 2015. There are a number of problems including the fact that the Scala code tries to run a bash script (mahout/bin/mahout) which does not work of course, the sbin scripts have not been ported to windows, and the winutils are missing if hadoop is not installed.

(1) Install scala, then unzip spark/hadoop/mahout into the root of C: under their respective product names.

(2) Rename \mahout\bin\mahout to (we will not need it)

(3) Compile the following Win32 C++ program and copy the executable to a file named C:\mahout\bin\mahout (that's right - no .exe suffix, like a Linux executable)

#include "stdafx.h"
#define BUFSIZE 4096
int _tmain(int argc, _TCHAR* argv[]) {
    DWORD dwLength;     LPTSTR pszBuffer;
    pszBuffer = (LPTSTR)malloc(BUFSIZE*sizeof(TCHAR));
    dwLength = GetEnvironmentVariable(VARNAME, pszBuffer, BUFSIZE);
    if (dwLength > 0) { _tprintf(TEXT("%s\n"), pszBuffer); return 0; }
    return 1;

(4) Create the script \mahout\bin\mahout.bat and paste in the content below, although the exact names of the jars in the _CP class paths will depend on the versions of spark and mahout. Update any paths per your installation. Use 8.3 path names without spaces in them. Note that you cannot use wildcards/asterisks in the classpaths here.

set SCALA_HOME=C:\Progra~2\scala
set SPARK_HOME=C:\spark
set HADOOP_HOME=C:\hadoop
set MAHOUT_HOME=C:\mahout
set MASTER=local[2]
set path=%SCALA_HOME%\bin;%SPARK_HOME%\bin;%PATH%
set SPARK_CP=%SPARK_HOME%\conf\;%SPARK_HOME%\lib\xxx.jar;...other jars...
set MAHOUT_CP=%MAHOUT_HOME%\lib\xxx.jar;...other jars...;%MAHOUT_HOME%\xxx.jar;...other jars...;%SPARK_CP%;%MAHOUT_HOME%\lib\spark\xxx.jar;%MAHOUT_HOME%\lib\hadoop\xxx.jar;%MAHOUT_HOME%\src\conf;%JAVA_HOME%\lib\tools.jar
start "master0" "%JAVA_HOME%\bin\java" -cp "%SPARK_CP%" -Xms1g -Xmx1g org.apache.spark.deploy.master.Master --ip localhost --port 7077 --webui-port 8082 >>out-master0.log 2>>out-master0.err
start "worker1" "%JAVA_HOME%\bin\java" -cp "%SPARK_CP%" -Xms1g -Xmx1g org.apache.spark.deploy.worker.Worker spark://localhost:7077 --webui-port 8083 >>out-worker1.log 2>>out-worker1.err may add more workers here...
"%JAVA_HOME%\bin\java" -Xmx4g -classpath "%MAHOUT_CP%" ""

The name of the variable MAHOUT_CP should not be changed, as it is referenced in the C++ code.

Of course you can comment-out the code that launches the Spark master and worker because Mahout will run Spark as-needed; I just put it in the batch job to show you how to launch it if you wanted to use Spark without Mahout.

(5) The following tutorial is a good place to begin:

You can bring up the Mahout Spark instance at:

"C:\Program Files (x86)\Google\Chrome\Application\chrome" --disable-web-security http://localhost:4040

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

Set registry item for your server instance. For example:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL.2\MSSQLServer\BackupDirectory

How can I check if a MySQL table exists with PHP?

Even faster than a bad query:

SELECT count((1)) as `ct`  FROM INFORMATION_SCHEMA.TABLES where table_schema ='yourdatabasename' and table_name='yourtablename';

This way you can just retrieve one field and one value. .016 seconds for my slower system.

Removing index column in pandas when reading a csv

DataFrames and Series always have an index. Although it displays alongside the column(s), it is not a column, which is why del df['index'] did not work.

If you want to replace the index with simple sequential numbers, use df.reset_index().

To get a sense for why the index is there and how it is used, see e.g. 10 minutes to Pandas.

AngularJS - Attribute directive input value change

There's a great example in the AngularJS docs.

It's very well commented and should get you pointed in the right direction.

A simple example, maybe more so what you're looking for is below:



<div ng-app="myDirective" ng-controller="x">
    <input type="text" ng-model="test" my-directive>


angular.module('myDirective', [])
    .directive('myDirective', function () {
    return {
        restrict: 'A',
        link: function (scope, element, attrs) {
            scope.$watch(attrs.ngModel, function (v) {
                console.log('value changed, new value is: ' + v);

function x($scope) {
    $scope.test = 'value here';

Edit: Same thing, doesn't require ngModel jsfiddle:


angular.module('myDirective', [])
    .directive('myDirective', function () {
    return {
        restrict: 'A',
        scope: {
            myDirective: '='
        link: function (scope, element, attrs) {
            // set the initial value of the textbox
  'old-value', scope.myDirective);

            // detect outside changes and update our input
            scope.$watch('myDirective', function (val) {

            // on blur, update the value in scope
            element.bind('propertychange keyup paste', function (blurEvent) {
                if ('old-value') != element.val()) {
                    console.log('value changed, new value is: ' + element.val());
                    scope.$apply(function () {
                        scope.myDirective = element.val();
              'old-value', element.val());

function x($scope) {
    $scope.test = 'value here';

What do 1.#INF00, -1.#IND00 and -1.#IND mean?

For anyone wondering about the difference between -1.#IND00 and -1.#IND (which the question specifically asked, and none of the answers address):


This specifically means a non-zero number divided by zero, e.g. 3.14 / 0 (source)

-1.#IND (a synonym for NaN)

This means one of four things (see wiki from source):

1) sqrt or log of a negative number

2) operations where both variables are 0 or infinity, e.g. 0 / 0

3) operations where at least one variable is already NaN, e.g. NaN * 5

4) out of range trig, e.g. arcsin(2)

CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true

(Edit) The previously recomended add-on is not available any longer, you may try this other one

For development purposes in Chrome, installing this add on will get rid of that specific error:

Access to XMLHttpRequest at '' 
from origin 'http://localhost:8080' has been blocked by CORS policy: The value of the 
'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' 
when the request's credentials mode is 'include'. The credentials mode of requests 
initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

After installing, make sure you add your url pattern to the Intercepted URLs by clicking on the AddOn's (CORS, green or red) icon and filling the appropriate textbox. An example URL pattern to add here that will work with http://localhost:8080 would be: *://*

Java Constructor Inheritance

When you inherit from Super this is what in reality happens:

public class Son extends Super{

  // If you dont declare a constructor of any type, adefault one will appear.
  public Son(){
    // If you dont call any other constructor in the first line a call to super() will be placed instead.


So, that is the reason, because you have to call your unique constructor, since"Super" doesn't have a default one.

Now, trying to guess why Java doesn't support constructor inheritance, probably because a constructor only makes sense if it's talking about concrete instances, and you shouldn't be able to create an instance of something when you don't know how it's defined (by polymorphism).

How to push files to an emulator instance using Android Studio

Open command prompt and give the platform-tools path of the sdk. Eg:- C:\Android\sdk\platform-tools> Then type 'adb push' command like below,

C:\Android\sdk\platform-tools>adb push C:\MyFiles\fileName.txt /sdcard/fileName.txt

This command push the file to the root folder of the emulator.

What does file:///android_asset/www/index.html mean?

It took me more than 4 hours to fix this problem. I followed the guide from

I'm using Android Studio (Eclipse with ADT could not work properly because of the build problem).

Solution that worked for me:

  1. I put the /assets/www/index.html under app/src/main/assets directory. (take care AndroidStudio has different perspectives like Project or Android)

  2. use super.loadUrl("file:///android_asset/www/index.html"); instead of super.loadUrl("file:///android_assets/www/index.html"); (no s)

Returning JSON from PHP to JavaScript?

There's a JSON section in the PHP's documentation. You'll need PHP 5.2.0 though.

As of PHP 5.2.0, the JSON extension is bundled and compiled into PHP by default.

If you don't, here's the PECL library you can install.

    $arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);

    echo json_encode($arr); // {"a":1,"b":2,"c":3,"d":4,"e":5}

Split array into two parts without for loop in java

You can use System.arraycopy().

int[] source = new int[1000];

int[] part1 = new int[500];
int[] part2 = new int[500];

//              (src   , src-offset  , dest , offset, count)
System.arraycopy(source, 0           , part1, 0     , part1.length);
System.arraycopy(source, part1.length, part2, 0     , part2.length);