Programs & Examples On #Updatepanel

UpdatePanel is an ASP.NET AJAX control which allows page content to be updated asynchronously.

ASP.NET Display "Loading..." message while update panel is updating

You can use code as below when

using Image as Loading

<asp:UpdateProgress id="updateProgress" runat="server">
        <div style="position: fixed; text-align: center; height: 100%; width: 100%; top: 0; right: 0; left: 0; z-index: 9999999; background-color: #000000; opacity: 0.7;">
            <asp:Image ID="imgUpdateProgress" runat="server" ImageUrl="~/images/ajax-loader.gif" AlternateText="Loading ..." ToolTip="Loading ..." style="padding: 10px;position:fixed;top:45%;left:50%;" />

using Text as Loading

<asp:UpdateProgress id="updateProgress" runat="server">
        <div style="position: fixed; text-align: center; height: 100%; width: 100%; top: 0; right: 0; left: 0; z-index: 9999999; background-color: #000000; opacity: 0.7;">
            <span style="border-width: 0px; position: fixed; padding: 50px; background-color: #FFFFFF; font-size: 36px; left: 40%; top: 40%;">Loading ...</span>

RegisterStartupScript from code behind not working when Update Panel is used

You need to use ScriptManager.RegisterStartupScript for Ajax.

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

ASP.NET postback with JavaScript

If anyone's having trouble with this (as I was), you can get the postback code for a button by adding the UseSubmitBehavior="false" attribute to it. If you examine the rendered source of the button, you'll see the exact javascript you need to execute. In my case it was using the name of the button rather than the id.

Can't get ScriptManager.RegisterStartupScript in WebControl nested in UpdatePanel to work

When you call ScriptManager.RegisterStartupScript, the "Control" parameter must be a control that is within an UpdatePanel that will be updated. You need to change it to:

ScriptManager.RegisterStartupScript(this, this.GetType(), Guid.NewGuid().ToString(), script, true);

ModalPopupExtender OK Button click event not firing?

I've found a way to validate a modalpopup without a postback.

In the ModalPopupExtender I set the OnOkScript to a function e.g ValidateBeforePostBack(), then in the function I call Page_ClientValidate for the validation group I want, do a check and if it fails, keep the modalpopup showing. If it passes, I call __doPostBack.

function ValidateBeforePostBack(){ 
     if (Page_IsValid) { __doPostBack('',''); } 
     else { $find('mpeBehaviourID').show(); } 

round() for float in C++

The C++03 standard relies on the C90 standard for what the standard calls the Standard C Library which is covered in the draft C++03 standard (closest publicly available draft standard to C++03 is N1804) section 1.2 Normative references:

The library described in clause 7 of ISO/IEC 9899:1990 and clause 7 of ISO/IEC 9899/Amd.1:1995 is hereinafter called the Standard C Library.1)

If we go to the C documentation for round, lround, llround on cppreference we can see that round and related functions are part of C99 and thus won't be available in C++03 or prior.

In C++11 this changes since C++11 relies on the C99 draft standard for C standard library and therefore provides std::round and for integral return types std::lround, std::llround :

#include <iostream>
#include <cmath>

int main()
    std::cout << std::round( 0.4 ) << " " << std::lround( 0.4 ) << " " << std::llround( 0.4 ) << std::endl ;
    std::cout << std::round( 0.5 ) << " " << std::lround( 0.5 ) << " " << std::llround( 0.5 ) << std::endl ;
    std::cout << std::round( 0.6 ) << " " << std::lround( 0.6 ) << " " << std::llround( 0.6 ) << std::endl ;

Another option also from C99 would be std::trunc which:

Computes nearest integer not greater in magnitude than arg.

#include <iostream>
#include <cmath>

int main()
    std::cout << std::trunc( 0.4 ) << std::endl ;
    std::cout << std::trunc( 0.9 ) << std::endl ;
    std::cout << std::trunc( 1.1 ) << std::endl ;


If you need to support non C++11 applications your best bet would be to use boost round, iround, lround, llround or boost trunc.

Rolling your own version of round is hard

Rolling your own is probably not worth the effort as Harder than it looks: rounding float to nearest integer, part 1, Rounding float to nearest integer, part 2 and Rounding float to nearest integer, part 3 explain:

For example a common roll your implementation using std::floor and adding 0.5 does not work for all inputs:

double myround(double d)
  return std::floor(d + 0.5);

One input this will fail for is 0.49999999999999994, (see it live).

Another common implementation involves casting a floating point type to an integral type, which can invoke undefined behavior in the case where the integral part can not be represented in the destination type. We can see this from the draft C++ standard section 4.9 Floating-integral conversions which says (emphasis mine):

A prvalue of a floating point type can be converted to a prvalue of an integer type. The conversion truncates; that is, the fractional part is discarded. The behavior is undefined if the truncated value cannot be represented in the destination type.[...]

For example:

float myround(float f)
  return static_cast<float>( static_cast<unsigned int>( f ) ) ;

Given std::numeric_limits<unsigned int>::max() is 4294967295 then the following call:

myround( 4294967296.5f ) 

will cause overflow, (see it live).

We can see how difficult this really is by looking at this answer to Concise way to implement round() in C? which referencing newlibs version of single precision float round. It is a very long function for something which seems simple. It seems unlikely that anyone without intimate knowledge of floating point implementations could correctly implement this function:

float roundf(x)
  int signbit;
  __uint32_t w;
  /* Most significant word, least significant word. */
  int exponent_less_127;


  /* Extract sign bit. */
  signbit = w & 0x80000000;

  /* Extract exponent field. */
  exponent_less_127 = (int)((w & 0x7f800000) >> 23) - 127;

  if (exponent_less_127 < 23)
      if (exponent_less_127 < 0)
          w &= 0x80000000;
          if (exponent_less_127 == -1)
            /* Result is +1.0 or -1.0. */
            w |= ((__uint32_t)127 << 23);
          unsigned int exponent_mask = 0x007fffff >> exponent_less_127;
          if ((w & exponent_mask) == 0)
            /* x has an integral value. */
            return x;

          w += 0x00400000 >> exponent_less_127;
          w &= ~exponent_mask;
      if (exponent_less_127 == 128)
        /* x is NaN or infinite. */
        return x + x;
        return x;
  return x;

On the other hand if none of the other solutions are usable newlib could potentially be an option since it is a well tested implementation.

What is the difference between JDK and JRE?

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

JRE is an acronym for Java Runtime Environment.It is used to provide runtime environment.It is the implementation of JVM.It physically exists.It contains set of libraries + other files that JVM uses at runtime

JDK is an acronym for Java Development Kit.It physically exists.It contains JRE + development tools

Iterate over object keys in node.js

Also remember that you can pass a second argument to the .forEach() function specifying the object to use as the this keyword.

// myOjbect is the object you want to iterate.
// Notice the second argument (secondArg) we passed to .forEach.
Object.keys(myObject).forEach(function(element, key, _array) {
  // element is the name of the key.
  // key is just a numerical value for the array
  // _array is the array of all the keys

  // this keyword = secondArg;;
}, secondArg);

Why does git perform fast-forward merges by default?

Let me expand a bit on a VonC's very comprehensive answer:

First, if I remember it correctly, the fact that Git by default doesn't create merge commits in the fast-forward case has come from considering single-branch "equal repositories", where mutual pull is used to sync those two repositories (a workflow you can find as first example in most user's documentation, including "The Git User's Manual" and "Version Control by Example"). In this case you don't use pull to merge fully realized branch, you use it to keep up with other work. You don't want to have ephemeral and unimportant fact when you happen to do a sync saved and stored in repository, saved for the future.

Note that usefulness of feature branches and of having multiple branches in single repository came only later, with more widespread usage of VCS with good merging support, and with trying various merge-based workflows. That is why for example Mercurial originally supported only one branch per repository (plus anonymous tips for tracking remote branches), as seen in older revisions of "Mercurial: The Definitive Guide".

Second, when following best practices of using feature branches, namely that feature branches should all start from stable version (usually from last release), to be able to cherry-pick and select which features to include by selecting which feature branches to merge, you are usually not in fast-forward situation... which makes this issue moot. You need to worry about creating a true merge and not fast-forward when merging a very first branch (assuming that you don't put single-commit changes directly on 'master'); all other later merges are of course in non fast-forward situation.


Git push results in "Authentication Failed"

May you have changed password recently for you git account You could try the git push with -u option

git push -u origin branch_name_that_you_want_to_push

After executing above command it will ask for password provide your updated password

Hope it may help you

T-SQL: Selecting rows to delete via joins

I would use this syntax

Delete a 
from TableA a
Inner Join TableB b
on  a.BId = b.BId
WHERE [filter condition]

Increment a Integer's int value?

As Grodriguez says, Integer objects are immutable. The problem here is that you're trying to increment the int value of the player ID rather than the ID itself. In Java 5+, you can just write playerID++.

As a side note, never ever call Integer's constructor. Take advantage of autoboxing by just assigning ints to Integers directly, like Integer foo = 5. This will use Integer.valueOf(int) transparently, which is superior to the constructor because it doesn't always have to create a new object.

Eclipse DDMS error "Can't bind to local 8600 for debugger"

For me, this was due to the fact that I was trying to debug using eclipse yet also running Android Studio. Both programs were trying to monitor android devices on the similar ports. Either quit all IDEs other than one, or modify the port number used for debugging in the IDE preferences so they are not similar.

How do I set GIT_SSL_NO_VERIFY for specific repos only?

Like what Thirumalai said, but inside of the cloned repository and without --global. I.e.,

  1. GIT_SSL_NO_VERIFY=true git clone https://url
  2. cd <directory-of-the-clone>
  3. git config http.sslVerify false

concatenate two database columns into one resultset column

The SQL standard way of doing this would be:

SELECT COALESCE(field1, '') || COALESCE(field2, '') || COALESCE(field3, '') FROM table1


INSERT INTO table1 VALUES ('hello', null, 'world');
SELECT COALESCE(field1, '') || COALESCE(field2, '') || COALESCE(field3, '') FROM table1;


How to check if type is Boolean

  • The most readable: val === false || val === true.
  • Also readable: typeof variable == typeof true.
  • The shortest, but not readable at all: !!val === val.


    • [!!] The double exclamation mark converts the value into a Boolean.
    • [===] The triple equals test for strict equality: both the type (Boolean) and the value have to be the same.
    • If the original value is not a Boolean one, it won't pass the triple equals test. If it is a Boolean variable, it will pass the triple equals test (with both type & value).


    • !!5 === 5 // false
    • !!'test' === 'test' // false
    • let val = new Date(); !!val === val // false
    • !!true === true // true
    • !!false === false // true

What is the naming convention in Python for variable and function names?

Most python people prefer underscores, but even I am using python since more than 5 years right now, I still do not like them. They just look ugly to me, but maybe that's all the Java in my head.

I simply like CamelCase better since it fits better with the way classes are named, It feels more logical to have SomeClass.doSomething() than SomeClass.do_something(). If you look around in the global module index in python, you will find both, which is due to the fact that it's a collection of libraries from various sources that grew overtime and not something that was developed by one company like Sun with strict coding rules. I would say the bottom line is: Use whatever you like better, it's just a question of personal taste.

Get first and last date of current month with JavaScript or jQuery

Very simple, no library required:

var date = new Date();
var firstDay = new Date(date.getFullYear(), date.getMonth(), 1);
var lastDay = new Date(date.getFullYear(), date.getMonth() + 1, 0);

or you might prefer:

var date = new Date(), y = date.getFullYear(), m = date.getMonth();
var firstDay = new Date(y, m, 1);
var lastDay = new Date(y, m + 1, 0);


Some browsers will treat two digit years as being in the 20th century, so that:

new Date(14, 0, 1);

gives 1 January, 1914. To avoid that, create a Date then set its values using setFullYear:

var date = new Date();
date.setFullYear(14, 0, 1); // 1 January, 14

"The import org.springframework cannot be resolved."

I imported a project as 'Existing Maven Project' and was getting this issue.

Resolution: Changed Java Build Path of JRE System Library to Workspace defailt JRE [jdk 1.8]


Right click on project -> build path -> configure build path -> Libraries Tab -> double click JRE System Library -> change to Workspace defailt JRE [jdk 1.8]

Where are include files stored - Ubuntu Linux, GCC

See here: Search Path


#include <stdio.h>

When the include file is in brackets the preprocessor first searches in paths specified via the -I flag. Then it searches the standard include paths (see the above link, and use the -v flag to test on your system).

#include "myFile.h"

When the include file is in quotes the preprocessor first searches in the current directory, then paths specified by -iquote, then -I paths, then the standard paths.

-nostdinc can be used to prevent the preprocessor from searching the standard paths at all.

Environment variables can also be used to add search paths.

When compiling if you use the -v flag you can see the search paths used.

RegEx match open tags except XHTML self-contained tags

I suggest using QueryPath for parsing XML and HTML in PHP. It's basically much the same syntax as jQuery, only it's on the server side.

Getting HTML elements by their attribute names

Just another answer
    function(el) {return el.getAttribute('property') == '';}

In future
    (el) => el.getAttribute('property') == ''

3rd party edit


  • The call() method calls a function with a given this value and arguments provided individually.

  • The filter() method creates a new array with all elements that pass the test implemented by the provided function.

Given this html markup

<span property="a">apple - no match</span>
<span property="v:name">onion - match</span>
<span property="b">root - match</span>
<span property="v:name">tomato - match</span>
<br />
<button onclick="findSpan()">find span</button>

you can use this javascript

function findSpan(){

    var spans = document.getElementsByTagName('span');
    var spansV =
         function(el) {return el.getAttribute('property') == 'v:name';}
    return spansV;

See demo

Java - Convert image to Base64

You can create a large array and then copy it to a new array using System.arrayCopy

        int contentLength = 100000000;
        byte[] byteArray = new byte[contentLength];

        BufferedInputStream inputStream = new BufferedInputStream(connection.getInputStream());
        while ((bytesRead = != -1)
            byteArray[count++] = (byte)bytesRead;

        byte[] destArray = new byte[count];
        System.arraycopy(byteArray, 0, destArray , 0, count);

destArray will contain the information you want

List rows after specific date

Simply put:

dob > '1/21/2012'

Where 1/21/2012 is the date and you want all data, including that date.

dob BETWEEN '1/21/2012' AND '2/22/2012'

Use a between if you're selecting time between two dates

Using multiple .cpp files in c++ program?

In C/C++ you have header files (*.H). There you declare your functions/classes. So for example you will have to #include "second.h" to your main.cpp file.

In second.h you just declare like this void yourFunction(); In second.cpp you implement it like

void yourFunction() { 

Don't forget to #include "second.h" also in the beginning of second.cpp

Hope this helps:)

Handling exceptions from Java ExecutorService tasks

I got around it by wrapping the supplied runnable submitted to the executor.

CompletableFuture.runAsync(() -> {
        try {
        } catch (Throwable e) {
    , "runAsync", e);
}, executorService);

Check to see if cURL is installed locally?

cURL is disabled for most hosting control panels for security reasons, but it's required for a lot of php applications. It's not unusual for a client to request it. Since the risk of enabling cURL is minimal, you are probably better off enabling it than losing a customer. It's simply a utility that helps php scripts fetch things using standard Internet URLs.

To enable cURL, you will remove curl_exec from the "disabled list" in the control panel php advanced settings. You will also find a disabled list in the various php.ini files; look in /etc/php.ini and other paths that might exist for your control panel. You will need to restart Apache to make the change take effect.

service httpd restart

To confirm whether cURL is enabled or disabled, create a file somewhere in your system and paste the following contents.

echo '<pre>';
echo '</pre>';

Save the file as testcurl.php and then run it as a php script.

php testcurl.php

If cURL is disabled you will see this error.

Fatal error: Call to undefined function curl_version() in testcurl.php on line 2

If cURL is enabled you will see a long list of attributes, like this.

array(9) {
string(6) "7.11.2"
string(13) "i386-pc-win32"
string(15) " OpenSSL/0.9.7c"
string(5) "1.1.4"
array(9) {
string(3) "ftp"
string(6) "gopher"
string(6) "telnet"
string(4) "dict"
string(4) "ldap"
string(4) "http"
string(4) "file"
string(5) "https"
string(4) "ftps"

Can't get Python to import from a different folder

You're missing From the Python tutorial:

The files are required to make Python treat the directories as containing packages; this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later on the module search path. In the simplest case, can just be an empty file, but it can also execute initialization code for the package or set the __all__ variable, described later.

Put an empty file named in your Models directory, and all should be golden.

"getaddrinfo failed", what does that mean?

The problem, in my case, was that some install at some point defined an environment variable http_proxy on my machine when I had no proxy.

Removing the http_proxy environment variable fixed the problem.

How to remove frame from matplotlib (pyplot.figure vs matplotlib.figure ) (frameon=False Problematic in matplotlib)

df = pd.DataFrame({
'client_scripting_ms' : client_scripting_ms,
 'apimlayer' : apimlayer, 'server' : server
}, index = index)

ax = df.plot(kind = 'barh', 
     stacked = True,
     title = "Chart",
     width = 0.20, 

plt.legend(loc='upper right', frameon=True)



How can I use UIColorFromRGB in Swift?

That can be simply done by using this initialization

view.backgroundColor = UIColor(hex: "067AB5")

What's the best way to iterate an Android Cursor?

I'd just like to point out a third alternative which also works if the cursor is not at the start position:

if (cursor.moveToFirst()) {
    do {
        // do what you need with the cursor here
    } while (cursor.moveToNext());

How to remove square brackets from list in Python?

def listToStringWithoutBrackets(list1):
    return str(list1).replace('[','').replace(']','')

Proper MIME media type for PDF files

This is a convention defined in RFC 2045 - Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies.

  1. Private [subtype] values (starting with "X-") may be defined bilaterally between two cooperating agents without outside registration or standardization. Such values cannot be registered or standardized.

  2. New standard values should be registered with IANA as described in RFC 2048.

A similar restriction applies to the top-level type. From the same source,

If another top-level type is to be used for any reason, it must be given a name starting with "X-" to indicate its non-standard status and to avoid a potential conflict with a future official name.

(Note that per RFC 2045, "[m]atching of media type and subtype is ALWAYS case-insensitive", so there's no difference between the interpretation of 'X-' and 'x-'.)

So it's fair to guess that "application/x-foo" was used before the IANA defined "application/foo". And it still might be used by folks who aren't aware of the IANA token assignment.

As Chris Hanson said MIME types are controlled by the IANA. This is detailed in RFC 2048 - Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures. According to RFC 3778, which is cited by the IANA as the definition for "application/pdf",

The application/pdf media type was first registered in 1993 by Paul Lindner for use by the gopher protocol; the registration was subsequently updated in 1994 by Steve Zilles.

The type "application/pdf" has been around for well over a decade. So it seems to me that wherever "application/x-pdf" has been used in new apps, the decision may not have been deliberate.

How to check if a value exists in a dictionary (python)

In Python 3 you can use the values() function of the dictionary. It returns a view object of the values. This, in turn, can be passed to the iter function which returns an iterator object. The iterator can be checked using in, like this,

'one' in iter(d.values())

Or you can use the view object directly since it is similar to a list

'one' in d.values()

How to stop a thread created by implementing runnable interface?

How to stop a thread created by implementing runnable interface?

There are many ways that you can stop a thread but all of them take specific code to do so. A typical way to stop a thread is to have a volatile boolean shutdown field that the thread checks every so often:

  // set this to true to stop the thread
  volatile boolean shutdown = false;
  public void run() {
      while (!shutdown) {
          // continue processing

You can also interrupt the thread which causes sleep(), wait(), and some other methods to throw InterruptedException. You also should test for the thread interrupt flag with something like:

  public void run() {
      while (!Thread.currentThread().isInterrupted()) {
          // continue processing
          try {
          } catch (InterruptedException e) {
              // good practice

Note that that interrupting a thread with interrupt() will not necessarily cause it to throw an exception immediately. Only if you are in a method that is interruptible will the InterruptedException be thrown.

If you want to add a shutdown() method to your class which implements Runnable, you should define your own class like:

public class MyRunnable implements Runnable {
    private volatile boolean shutdown;
    public void run() {
        while (!shutdown) {
    public void shutdown() {
        shutdown = true;

correct way to define class variables in Python

Neither way is necessarily correct or incorrect, they are just two different kinds of class elements:

  • Elements outside the __init__ method are static elements; they belong to the class.
  • Elements inside the __init__ method are elements of the object (self); they don't belong to the class.

You'll see it more clearly with some code:

class MyClass:
    static_elem = 123

    def __init__(self):
        self.object_elem = 456

c1 = MyClass()
c2 = MyClass()

# Initial values of both elements
>>> print c1.static_elem, c1.object_elem 
123 456
>>> print c2.static_elem, c2.object_elem
123 456

# Nothing new so far ...

# Let's try changing the static element
MyClass.static_elem = 999

>>> print c1.static_elem, c1.object_elem
999 456
>>> print c2.static_elem, c2.object_elem
999 456

# Now, let's try changing the object element
c1.object_elem = 888

>>> print c1.static_elem, c1.object_elem
999 888
>>> print c2.static_elem, c2.object_elem
999 456

As you can see, when we changed the class element, it changed for both objects. But, when we changed the object element, the other object remained unchanged.

How to change column datatype from character to numeric in PostgreSQL 8.4

If your VARCHAR column contains empty strings (which are not the same as NULL for PostgreSQL as you might recall) you will have to use something in the line of the following to set a default:

            USING COALESCE(NULLIF(code, '')::NUMERIC, 0);

(found with the help of this answer)

redistributable offline .NET Framework 3.5 installer for Windows 8

You don't have to copy everything to C:\dotnet35. Usually all the files are already copied to the folder C:\Windows\WinSxS. Then the command becomes (assuming Windows was installed to C:): "Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:C:\Windows\WinSxS /LimitAccess" If not you can also point the command to the DVD directly. Then the command becomes (assuming DVD is mounted to D:): "Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:D:\sources\sxs /LimitAccess".

How to dynamically add elements to String array?

Arrays in Java have a defined size, you cannot change it later by adding or removing elements (you can read some basics here).

Instead, use a List:

ArrayList<String> mylist = new ArrayList<String>();
mylist.add(mystring); //this adds an element to the list.

Of course, if you know beforehand how many strings you are going to put in your array, you can create an array of that size and set the elements by using the correct position:

String[] myarray = new String[numberofstrings];
myarray[23] = string24; //this sets the 24'th (first index is 0) element to string24.

Can we add div inside table above every <tr>?

You can't put a div directly inside a table but you can put div inside td or th element.

For that you need to do is make sure the div is inside an actual table cell, a td or th element, so do that:


      <p>I'm text in a div.</p>

For more information :-

How can I disable inherited css styles?

Cascading Style Sheet are designed for inheritance. Inheritance is intrinsic to their existence. If it wasn't built to be cascading, they would only be called "Style Sheets".

That said, if an inherited style doesn't fit your needs, you'll have to override it with another style closer to the object. Forget about the notion of "blocking inheritance".

You can also choose the more granular solution by giving styles to every individual objects, and not giving styles to the general tags like div, p, pre, etc.

For example, you can use styles that start with # for objects with a specific ID:

    font-family:MS Trebuchet;
<div id="dividstyle">Hello world</div>

You can define classes for objects:

    font-family: Calibri;
<div class="divclassstyle">Hello world</div>

Hope it helps.

Correct way to write line to file?

To write text in a file in the flask can be used:

filehandle = open("text.txt", "w")
filebuffer = ["hi","welcome","yes yes welcome"]

Underscore prefix for property and method names in JavaScript

Welcome to 2019!

It appears a proposal to extend class syntax to allow for # prefixed variable to be private was accepted. Chrome 74 ships with this support.

_ prefixed variable names are considered private by convention but are still public.

This syntax tries to be both terse and intuitive, although it's rather different from other programming languages.

Why was the sigil # chosen, among all the Unicode code points?

  • @ was the initial favorite, but it was taken by decorators. TC39 considered swapping decorators and private state sigils, but the committee decided to defer to the existing usage of transpiler users.
  • _ would cause compatibility issues with existing JavaScript code, which has allowed _ at the start of an identifier or (public) property name for a long time.

This proposal reached Stage 3 in July 2017. Since that time, there has been extensive thought and lengthy discussion about various alternatives. In the end, this thought process and continued community engagement led to renewed consensus on the proposal in this repository. Based on that consensus, implementations are moving forward on this proposal.


How to automatically insert a blank row after a group of data

I have a large file in excel dealing with purchase and sale of mutual fund units. Number of rows in a worksheet exceeds 4000. I have no experience with VBA and would like to work with basic excel. Taking the cue from the solutions suggested above, I tried to solve the problem ( to insert blank rows automatically) in the following manner:

  1. I sorted my file according to control fields
  2. I added a column to the file
  3. I used the "IF" function to determine when there is a change in the control data .
  4. If there is a change the result will indicate "yes", otherwise "no"
  5. Then I filtered the data to group all "yes" items
  6. I copied mutual fund names, folio number etc (no financial data)
  7. Then I removed the filter and sorted the file again. The result is a row added at the desired place. (It is not entirely a blank row, because if it is fully blank, sorting will not place the row at the desired place.)
  8. After sorting, you can easily delete all values to get a completely blank row.

This method also may be tried by the readers.

Git: "Not currently on any branch." Is there an easy way to get back on a branch, while keeping the changes?

git checkout master

That's result something like this:

Warning: you are leaving 2 commits behind, not connected to
any of your branches:

1e7822f readme
0116b5b returned to clean django

If you want to keep them by creating a new branch, this may be a good time to do so with:
git branch new_branch_name 1e7822f25e376d6a1182bb86a0adf3a774920e1e

So, let's do it:

git merge 1e7822f25e376d6a1182bb86a0adf3a774920e1e

Unknown URL content://downloads/my_downloads

For those who are getting Error Unknown URI: content://downloads/public_downloads. I managed to solve this by getting a hint given by @Commonsware in this answer. I found out the class FileUtils on GitHub. Here InputStream methods are used to fetch file from Download directory.

 // DownloadsProvider
            else if (isDownloadsDocument(uri)) {

                final String id = DocumentsContract.getDocumentId(uri);

                if (id != null && id.startsWith("raw:")) {
                    return id.substring(4);

                String[] contentUriPrefixesToTry = new String[]{

                for (String contentUriPrefix : contentUriPrefixesToTry) {
                    Uri contentUri = ContentUris.withAppendedId(Uri.parse(contentUriPrefix), Long.valueOf(id));
                    try {
                        String path = getDataColumn(context, contentUri, null, null);
                        if (path != null) {
                            return path;
                    } catch (Exception e) {}

                // path could not be retrieved using ContentResolver, therefore copy file to accessible cache using streams
                String fileName = getFileName(context, uri);
                File cacheDir = getDocumentCacheDir(context);
                File file = generateFileName(fileName, cacheDir);
                String destinationPath = null;
                if (file != null) {
                    destinationPath = file.getAbsolutePath();
                    saveFileFromUri(context, uri, destinationPath);

                return destinationPath;

When to use RSpec let()?

"before" by default implies before(:each). Ref The Rspec Book, copyright 2010, page 228.

before(scope = :each, options={}, &block)

I use before(:each) to seed some data for each example group without having to call the let method to create the data in the "it" block. Less code in the "it" block in this case.

I use let if I want some data in some examples but not others.

Both before and let are great for DRYing up the "it" blocks.

To avoid any confusion, "let" is not the same as before(:all). "Let" re-evaluates its method and value for each example ("it"), but caches the value across multiple calls in the same example. You can read more about it here:

Accessing members of items in a JSONArray with Java

Java 8 is in the market after almost 2 decades, following is the way to iterate org.json.JSONArray with java8 Stream API.

import org.json.JSONArray;
import org.json.JSONObject;

public void access_org_JsonArray() {
    //Given: array
    JSONArray jsonArray = new JSONArray(Arrays.asList(new JSONObject(
                    new HashMap() {{
                        put("a", 100);
                        put("b", 200);
            new JSONObject(
                    new HashMap() {{
                        put("a", 300);
                        put("b", 400);

    //Then: convert to List<JSONObject>
    List<JSONObject> jsonItems = IntStream.range(0, jsonArray.length())
            .mapToObj(index -> (JSONObject) jsonArray.get(index))

    // you can access the array elements now
    jsonItems.forEach(arrayElement -> System.out.println(arrayElement.get("a")));
    // prints 100, 300

If the iteration is only one time, (no need to .collect)

    IntStream.range(0, jsonArray.length())
            .mapToObj(index -> (JSONObject) jsonArray.get(index))
            .forEach(item -> {

How to Create an excel dropdown list that displays text with a numeric hidden value

There are two types of drop down lists available (I am not sure since which version).

ActiveX Drop Down
You can set the column widths, so your hidden column can be set to 0.

Form Drop Down
You could set the drop down range to a hidden sheet and reference the cell adjacent to the selected item. This would also work with the ActiveX type control.

Detailed 500 error message, ASP + IIS 7.5

I have come to the same problem and fixed the same way as Alex K.

So if "Send Errors To Browser" is not working set also this:

Error Pages -> 500 -> Edit Feature Settings -> "Detailed Errors"

enter image description here

Also note that if the content of the error page sent back is quite short and you're using IE, IE will happily ignore the useful content sent back by the server and show you its own generic error page instead. You can turn this off in IE's options, or use a different browser.

Animate element transform rotate

As far as I know, basic animates can't animate non-numeric CSS properties.

I believe you could get this done using a step function and the appropriate css3 transform for the users browser. CSS3 transform is a bit tricky to cover all your browsers in (IE6 you need to use the Matrix filter, for instance).

EDIT: here's an example that works in webkit browsers (Chrome, Safari):

If you wanted to support IE9 only, you could use transform instead of -webkit-transform, or -moz-transform would support FireFox.

The trick used is to animate a CSS property we don't care about (text-indent) and then use its value in a step function to do the rotation:

step: function(now,fx) {

When should the xlsm or xlsb formats be used?

.xlsx loads 4 times longer than .xlsb and saves 2 times longer and has 1.5 times a bigger file. I tested this on a generated worksheet with 10'000 rows * 1'000 columns = 10'000'000 (10^7) cells of simple chained =…+1 formulas:

¦              ¦ .xlsx  ¦ .xlsb  ¦
¦ loading time ¦ 165s   ¦  43s   ¦
¦ saving time  ¦ 115s   ¦  61s   ¦
¦ file size    ¦  91 MB ¦  65 MB ¦

(Hardware: Core2Duo 2.3 GHz, 4 GB RAM, 5.400 rpm SATA II HD; Windows 7, under somewhat heavy load from other processes.)

Beside this, there should be no differences. More precisely,

both formats support exactly the same feature set

cites this blog post from 2006-08-29. So maybe the info that .xlsb does not support Ribbon code is newer than the upper citation, but I figure that forum source of yours is just wrong. When cracking open the binary file, it seems to condensedly mimic the OOXML file structure 1-to-1: Blog article from 2006-08-07

How does Java deal with multiple conditions inside a single IF statement

Yes,that is called short-circuiting.

Please take a look at this wikipedia page on short-circuiting

How to create Password Field in Model Django

Use widget as PasswordInput

from django import forms
class UserForm(forms.ModelForm):
    password = forms.CharField(widget=forms.PasswordInput)
    class Meta:
        model = User

Limit Get-ChildItem recursion depth

I tried to limit Get-ChildItem recursion depth using Resolve-Path

$PATH = "."
$folder = get-item $PATH 
$FolderFullName = $Folder.FullName
$PATHs = Resolve-Path $FolderFullName\*\*\*\
$Folders = $PATHs | get-item | where {$_.PsIsContainer}

But this works fine :

gci "$PATH\*\*\*\*"

How can I let a user download multiple files when a button is clicked?

This works in all browsers (IE11, Firefox, Microsoft Edge, Chrome and Chrome Mobile) My documents are in multiple select elements. The browsers seem to have issues when you try to do it too fast... So I used a timeout.

<select class="document">
    <option val="word.docx">some word document</option>

//user clicks a download button to download all selected documents
    $('#downloadDocumentsButton').click(function () {
        var interval = 1000;
        //select elements have class name of "document"
        $('.document').each(function (index, element) {
            var doc = $(element).val();
            if (doc) {
                setTimeout(function () {
                    window.location = doc;
                }, interval * (index + 1));

This solution uses promises:

function downloadDocs(docs) {
    docs[0].then(function (result) {
        if (result.web) {
        else {
            window.location = result.doc;
        if (docs.length > 1) {
            setTimeout(function () { return downloadDocs(docs.slice(1)); }, 2000);

 $('#downloadDocumentsButton').click(function () {
    var files = [];
    $('.document').each(function (index, element) {
        var doc = $(element).val();
        var ext = doc.split('.')[doc.split('.').length - 1];

        if (doc && $.inArray(ext, docTypes) > -1) {
            files.unshift(Promise.resolve({ doc: doc, web: false }));
        else if (doc && ($.inArray(ext, webTypes) > -1 || ext.includes('?'))) {
            files.push(Promise.resolve({ doc: doc, web: true }));


Create list of single item repeated N times

>>> [5] * 4
[5, 5, 5, 5]

Be careful when the item being repeated is a list. The list will not be cloned: all the elements will refer to the same list!

>>> x=[5]
>>> y=[x] * 4
>>> y
[[5], [5], [5], [5]]
>>> y[0][0] = 6
>>> y
[[6], [6], [6], [6]]

Calculating how many days are between two dates in DB2?

I faced the same problem in Derby IBM DB2 embedded database in a java desktop application, and after a day of searching I finally found how it's done :

SELECT days (table1.datecolomn) - days (current date) FROM table1 WHERE days (table1.datecolomn) - days (current date) > 5

for more information check this site

Searching for Text within Oracle Stored Procedures

If you use UPPER(text), the like '%lah%' will always return zero results. Use '%LAH%'.

Get Mouse Position

If you're using Swing as your UI layer, you can use a Mouse-Motion Listener for this.

"for" vs "each" in Ruby

See "The Evils of the For Loop" for a good explanation (there's one small difference considering variable scoping).

Using each is considered more idiomatic use of Ruby.

connecting to mysql server on another PC in LAN

In Ubuntu Follow these steps:

  1. Set bind-address at /etc/mysql/mysql.conf.d

Change bind-address = to bind-address = 192.24.805.50 # your IP

  1. Grant permission for the remote machine

    mysql>GRANT ALL PRIVILEGES ON . TO 'root'@'[remoteip]' IDENTIFIED BY 'anypassword' WITH GRANT OPTION;

  2. Then try connect from remote machine

    mysql -u root -h 192.24.805.50 -p

C read file line by line

Use fgets() to read a line from a file handle.

How can I declare a global variable in Angular 2 / Typescript?

See for example Angular 2 - Implementation of shared services

export class MyGlobals {
  readonly myConfigValue:string = 'abc';

  providers: [MyGlobals],

class MyComponent {
  constructor(private myGlobals:MyGlobals) {

or provide individual values

  providers: [{provide: 'myConfigValue', useValue: 'abc'}],

class MyComponent {
  constructor(@Inject('myConfigValue') private myConfigValue:string) {

Repeat command automatically in Linux

Running commands periodically without cron is possible when we go with while.

As a command:

while true ; do command ; sleep 100 ; done &
[ ex: # while true;  do echo `date` ; sleep 2 ; done & ]


while true
do echo "Hello World"
sleep 100
done &

Do not forget the last & as it will put your loop in the background. But you need to find the process id with command "ps -ef | grep your_script" then you need to kill it. So kindly add the '&' when you running the script.

# ./ &

Here is the same loop as a script. Create file "" and put this in it:

while true; do 
    echo "Hello World" # Substitute this line for whatever command you want.
    sleep 100

Then run it by typing bash ./ &

Error "initializer element is not constant" when trying to initialize variable with const

I had this error in code that looked like this:

int A = 1;
int B = A;

The fix is to change it to this

int A = 1;
#define B A

The compiler assigns a location in memory to a variable. The second is trying a assign a second variable to the same location as the first - which makes no sense. Using the macro preprocessor solves the problem.

How many concurrent requests does a single Flask process receive?

No- you can definitely handle more than that.

Its important to remember that deep deep down, assuming you are running a single core machine, the CPU really only runs one instruction* at a time.

Namely, the CPU can only execute a very limited set of instructions, and it can't execute more than one instruction per clock tick (many instructions even take more than 1 tick).

Therefore, most concurrency we talk about in computer science is software concurrency. In other words, there are layers of software implementation that abstract the bottom level CPU from us and make us think we are running code concurrently.

These "things" can be processes, which are units of code that get run concurrently in the sense that each process thinks its running in its own world with its own, non-shared memory.

Another example is threads, which are units of code inside processes that allow concurrency as well.

The reason your 4 worker processes will be able to handle more than 4 requests is that they will fire off threads to handle more and more requests.

The actual request limit depends on HTTP server chosen, I/O, OS, hardware, network connection etc.

Good luck!

*instructions are the very basic commands the CPU can run. examples - add two numbers, jump from one instruction to another

Multiple REPLACE function in Oracle

In case all your source and replacement strings are just one character long, you can simply use the TRANSLATE function:

  SELECT translate('THIS IS UPPERCASE', 'THISUP', 'thisup') 

See the Oracle documentation for details.

When should we use Observer and Observable?

If the interviewer asks to implement Observer design pattern without using Observer classes and interfaces, you can use the following simple example!

MyObserver as observer interface

interface MyObserver {

    void update(MyObservable o, Object arg);

MyObservable as Observable class

class MyObservable
    ArrayList<MyObserver> myObserverList = new ArrayList<MyObserver>();

    boolean changeFlag = false;

    public void notifyObservers(Object o)
        if (hasChanged())
            for(MyObserver mo : myObserverList) {
                mo.update(this, o);

    public void addObserver(MyObserver o) {

    public void setChanged() {
        changeFlag = true;

    public boolean hasChanged() {
        return changeFlag;

    protected void clearChanged() {
        changeFlag = false;

    // ...

Your example with MyObserver and MyObservable!

class MessageBoard extends MyObservable {
  private String message;

  public String getMessage() {
    return message;

  public void changeMessage(String message) {
    this.message = message;

  public static void main(String[] args) {
    MessageBoard board = new MessageBoard();
    Student bob = new Student();
    Student joe = new Student();
    board.changeMessage("More Homework!");

class Student implements MyObserver {

  public void update(MyObservable o, Object arg) {
    System.out.println("Message board changed: " + arg);


How to initialize a list with constructor?

In general don't expose List<T> publicly, and don't provide setters for collection properties. Also, you may want to copy the elements of the passed list (as shown below). Otherwise changes to the original list will affect the Human instance.

public class Human
    public Human()

    public Human(IEnumerable<ContactNumber> contactNumbers)
        if (contactNumbers == null)
            throw new ArgumentNullException("contactNumbers");


    public IEnumerable<ContactNumber> ContactNumbers
        get { return _contactNumbers; }

    private readonly List<ContactNumber> _contactNumbers = new List<ContactNumber>();

Another option is to use the list constructor that takes a collection and remove the field initializer.

How to vertically center a "div" element for all browsers using CSS?

If someone cares for Internet Explorer 10 (and later) only, use flexbox:

.parent {_x000D_
    width: 500px;_x000D_
    height: 500px;_x000D_
    background: yellow;_x000D_
    display: -webkit-flex;_x000D_
    display: -ms-flexbox;_x000D_
    display: flex;_x000D_
    -webkit-justify-content: center;_x000D_
    -ms-flex-pack: center;_x000D_
    justify-content: center;_x000D_
    -webkit-align-items: center;_x000D_
    -ms-flex-align: center;_x000D_
    align-items: center;_x000D_
.centered {_x000D_
    width: 100px;_x000D_
    height: 100px;_x000D_
    background: blue;_x000D_
<div class="parent">_x000D_
    <div class="centered"></div>_x000D_

Flexbox support:

bundle install returns "Could not locate Gemfile"

You must be in the same directory of Gemfile

Python: subplot within a loop: first panel appears in wrong position

The problem is the indexing subplot is using. Subplots are counted starting with 1! Your code thus needs to read

fig=plt.figure(figsize=(15, 6),facecolor='w', edgecolor='k')
for i in range(10):

    #this part is just arranging the data for contourf 
    ind2 = py.find(zz==i+1)
    sfr_mass_mat = np.reshape(sfr_mass[ind2],(pixmax_x,pixmax_y))
    sfr_mass_sub = sfr_mass[ind2]
    zi = griddata(massloclist, sfrloclist, sfr_mass_sub,xi,yi,interp='nn')

    temp = 251+i  # this is to index the position of the subplot
    plt.subplots_adjust(hspace = .5,wspace=.001)

    #just annotating where each contour plot is being placed

Note the change in the line where you calculate temp

How to initialize std::vector from C-style array?

The quick generic answer:

std::vector<double> vec(carray,carray+carray_size); 

or question specific:

std::vector<double> w_(w,w+len); 

based on above: Don't forget that you can treat pointers as iterators

Reading numbers from a text file into an array in C

5623125698541159 is treated as a single number (out of range of int on most architecture). You need to write numbers in your file as

5 6 2 3 1 2 5  6 9 8 5 4 1 1 5 9  

for 16 numbers.

If your file has input


then change %d specifier in your fscanf to %d,.

  fscanf(myFile, "%d,", &numberArray[i] );  

Here is your full code after few modifications:

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

int main(){

    FILE *myFile;
    myFile = fopen("somenumbers.txt", "r");

    //read file into array
    int numberArray[16];
    int i;

    if (myFile == NULL){
        printf("Error Reading File\n");
        exit (0);

    for (i = 0; i < 16; i++){
        fscanf(myFile, "%d,", &numberArray[i] );

    for (i = 0; i < 16; i++){
        printf("Number is: %d\n\n", numberArray[i]);


    return 0;

Numpy first occurrence of value greater than existing value

I would go with

i = np.min(np.where(V >= x))

where V is vector (1d array), x is the value and i is the resulting index.

Git and nasty "error: cannot lock existing info/refs fatal"

This is how it works for me.

  1. look up the Apache DAV lock file on your server (e.g. /var/lock/apache2/DAVlock)
  2. delete it
  3. recreate it with write permissions for the webserver
  4. restart the webserver

Even faster alternative:

  1. look up the Apache DAV lock file on your server (e.g. /var/lock/apache2/DAVlock)
  2. Empty the file: cat /dev/null > /var/lock/apache2/DAVlock
  3. restart the webserver

Update just one gem with bundler

It appears that with newer versions of bundler (>= 1.14) it's:

bundle update --conservative gem-name

Get timezone from DateTime


A developer is responsible for keeping track of time-zone information associated with a DateTime value via some external mechanism.

A quote from an excellent article here. A must read for every .Net developer.

So my advice is to write a little wrapper class that suits your needs.

Javascript "Cannot read property 'length' of undefined" when checking a variable's length

You can simply check whether the element length is undefined or not just by using

var theHref = $(obj.mainImg_select).attr('href');
if (theHref){
   //get the length here if the element is not undefined
   elementLength = theHref.length
   // do stuff
} else {
   // do other stuff

Converting Decimal to Binary Java

The following converts decimal to Binary with Time Complexity : O(n) Linear Time and with out any java inbuilt function

private static int decimalToBinary(int N) {
    StringBuilder builder = new StringBuilder();
    int base = 2;
    while (N != 0) {
        int reminder = N % base;
        N = N / base;

    return Integer.parseInt(builder.reverse().toString());

how to return index of a sorted list?

you can use numpy.argsort

or you can do:

test =  [2,3,1,4,5]
idxs = list(zip(*sorted([(val, i) for i, val in enumerate(test)])))[1]

zip will rearange the list so that the first element is test and the second is the idxs.

Cannot resolve symbol AppCompatActivity - Support v7 libraries aren't recognized?

Include import; in your with other import statements. This would look like: enter image description here

this resolved my issue

Microsoft.ACE.OLEDB.12.0 provider is not registered

I've got the same error on a fully updated Windows Vista Family 64bit with a .NET application that I've compiled to 32 bit only - the program is installed in the programx86 folder on 64 bit machines. It fails with this error message even with 2007 access database provider installed, with/wiothout the SP2 of the same installed, IIS installed and app pool set for 32bit app support... yes I've tried every solution everywhere and still no success.

I switched my app to ACE OLE DB.12.0 because JET4.0 was failing on 64bit machines - and it's no better :-/ The most promising thread I've found was this:

but when you try to install the 64 bit "2010 Office System Driver Beta: Data Connectivity Components" it tells you that you can't install the 64 bit version without uninstalling all 32bit office applications... and installing the 32 bit version of 2010 Office System Driver Beta: Data Connectivity Components doesn't solve the initial problem, even with "Microsoft.ACE.OLEDB.12.0" as provider instead of "Microsoft.ACE.OLEDB.14.0" which that page (and others) recommend.

My next attempt will be to follow this post:

The issue is due to the wrong flavor of OLEDB32.DLL and OLEDB32r.DLL being registered on the server. If the 64 bit versions are registered, they need to be unregistered, and then the 32 bit versions registered instead. To fix this, unregister the versions located in %Program Files%/Common Files/System/OLE DB. Then register the versions at the same path but in the %Program Files (x86)% directory.

Has anyone else had so much trouble with both JET4.0 and OLEDB ACE providers on 64 bit machines? Has anyone found a solution if none of the others work?

font awesome icon in select option

Another solution is setting the size attribute on the select box.

Thus taking back control of the styling of the dropdown from the Apple style and displaying Font Awesome Icons correctly.

Invalid hook call. Hooks can only be called inside of the body of a function component

If all the above doesn't work, especially if having big size dependency (like my case), both building and loading were taking a minimum of 15 seconds, so it seems the delay gave a false message "Invalid hook call." So what you can do is give some time to ensure the build is completed before testing.

How to resolve Error : Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation

This error can be resolved by adding MessageBoxOptions.ServiceNotification.

MessageBox.Show(msg, "Print Error", System.Windows.Forms.MessageBoxButtons.YesNo, 

But it is not going to show any dialog box if your web application is installed on IIS or server.Because in IIS or server it is hosted on worker process which dont have any desktop.

Comparing two .jar files

Use Java Decompiler to turn the jar file into source code file, and then use WinMerge to perform comparison.

You should consult the copyright holder of the source code, to see whether it is OK to do so.

Entity Framework Join 3 Tables

I think it will be easier using syntax-based query:

var entryPoint = (from ep in dbContext.tbl_EntryPoint
                 join e in dbContext.tbl_Entry on ep.EID equals e.EID
                 join t in dbContext.tbl_Title on e.TID equals t.TID
                 where e.OwnerID == user.UID
                 select new {
                     UID = e.OwnerID,
                     TID = e.TID,
                     Title = t.Title,
                     EID = e.EID

And you should probably add orderby clause, to make sure Top(10) returns correct top ten items.

How to count the number of columns in a table using SQL?

Maybe something like this:

SELECT count(*) FROM user_tab_columns WHERE table_name = 'FOO'

this will count number of columns in a the table FOO

You can also just

select count(*) from all_tab_columns where owner='BAR' and table_name='FOO';

where the owner is schema and note that Table Names are upper case

How to fix a collation conflict in a SQL Server query?

Adding to the accepted answer, you can used DATABASE_DEFAULT as encoding.

This allows database to make choice for you and your code becomes more portable.

    FirstTable a
        INNER JOIN SecondTable b

Difference between maven scope compile and provided for JAR packaging

From the Maven Doc:

  • compile

    This is the default scope, used if none is specified. Compile dependencies are available in all classpaths of a project. Furthermore, those dependencies are propagated to dependent projects.

  • provided

    This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.


  • dependencies are not transitive (as you mentioned)
  • provided scope is only available on the compilation and test classpath, whereas compile scope is available in all classpaths.
  • provided dependencies are not packaged

python pandas remove duplicate columns

The way below will identify dupe columns to review what is going wrong building the dataframe originally.

dupes = pd.DataFrame(df.columns)

How do I prompt a user for confirmation in bash script?

echo Please, enter your name
read NAME
echo "Hi $NAME!"
if [ "x$NAME" = "xyes" ] ; then
 # do something

I s a short script to read in bash and echo back results.

How to make PyCharm always show line numbers

v. community 5.0.4 (linux): File -> Settings -> Editor -> General -> Appearance -> now check 'Show line numbers', confirm w. OK an voila :)

Preloading images with JavaScript

const preloadImage = src => 
  new Promise(r => {
    const image = new Image()
    image.onload = r
    image.onerror = r
    image.src = src

// Preload an image
await preloadImage('')

// Preload a bunch of images in parallel 
await Promise.all( => preloadImage(x.src)))

How can I check if a checkbox is checked?

This should work

    function validate() {
        if ($('#remeber').is(':checked')) {
        } else {
            alert("You didn't check it! Let me check it for you.");

Change Timezone in Lumen or Laravel 5

Use php time zones from php manual Php time zones

For example mine i changed from the UTC value in config/app.php with

'timezone' => 'Africa/Nairobi',

How can I concatenate a string and a number in Python?

If it worked the way you expected it to (resulting in "abc9"), what would "9" + 9 deliver? 18 or "99"?

To remove this ambiguity, you are required to make explicit what you want to convert in this case:

"abc" + str(9)

character count using jquery

Use .length to count number of characters, and $.trim() function to remove spaces, and replace(/ /g,'') to replace multiple spaces with just one. Here is an example:

   var str = "      Hel  lo       ";
   console.log(str.replace(/ /g,'').length); 



Source: How to count number of characters in a string with JQuery

JSON, REST, SOAP, WSDL, and SOA: How do they all link together

Imagine you are developing a web-application and you decide to decouple the functionality from the presentation of the application, because it affords greater freedom.

You create an API and let others implement their own front-ends over it as well. What you just did here is implement an SOA methodology, i.e. using web-services.

Web services make functional building-blocks accessible over standard Internet protocols independent of platforms and programming languages.

So, you design an interchange mechanism between the back-end (web-service) that does the processing and generation of something useful, and the front-end (which consumes the data), which could be anything. (A web, mobile, or desktop application, or another web-service). The only limitation here is that the front-end and back-end must "speak" the same "language".

That's where SOAP and REST come in. They are standard ways you'd pick communicate with the web-service.


SOAP internally uses XML to send data back and forth. SOAP messages have rigid structure and the response XML then needs to be parsed. WSDL is a specification of what requests can be made, with which parameters, and what they will return. It is a complete specification of your API.


REST is a design concept.

The World Wide Web represents the largest implementation of a system conforming to the REST architectural style.

It isn't as rigid as SOAP. RESTful web-services use standard URIs and methods to make calls to the webservice. When you request a URI, it returns the representation of an object, that you can then perform operations upon (e.g. GET, PUT, POST, DELETE). You are not limited to picking XML to represent data, you could pick anything really (JSON included)

Flickr's REST API goes further and lets you return images as well.

JSON and XML, are functionally equivalent, and common choices. There are also RPC-based frameworks like GRPC based on Protobufs, and Apache Thrift that can be used for communication between the API producers and consumers. The most common format used by web APIs is JSON because of it is easy to use and parse in every language.

NSNotificationCenter addObserver in Swift

Swift 5 Notification Observer

override func viewDidLoad() {
    NotificationCenter.default.addObserver(self, selector: #selector(batteryLevelChanged), name: UIDevice.batteryLevelDidChangeNotification, object: nil)

@objc func batteryLevelChanged(notification : NSNotification){
    //do here code

override func viewWillDisappear(_ animated: Bool) {
    NotificationCenter.default.removeObserver(self, name: UIDevice.batteryLevelDidChangeNotification, object: nil)


Excel formula to get week number in month (having Monday)

If week 1 always starts on the first Monday of the month try this formula for week number


That gets the week number from the date in A1 with no intermediate calculations - if you want to use your "Monday's date" in B1 you can use this version


Plotting with ggplot2: "Error: Discrete value supplied to continuous scale" on categorical y-axis

In my case, you need to convert the column(you think this column is numeric, but actually not) to numeric

# to 

Is Ruby pass by reference or by value?

There are already some great answers, but I want to post the definition of a pair of authorities on the subject, but also hoping someone might explain what said authorities Matz (creator of Ruby) and David Flanagan meant in their excellent O'Reilly book, The Ruby Programming Language.

[from 3.8.1: Object References]

When you pass an object to a method in Ruby, it is an object reference that is passed to the method. It is not the object itself, and it is not a reference to the reference to the object. Another way to say this is that method arguments are passed by value rather than by reference, but that the values passed are object references.

Because object references are passed to methods, methods can use those references to modify the underlying object. These modifications are then visible when the method returns.

This all makes sense to me until that last paragraph, and especially that last sentence. This is at best misleading, and at worse confounding. How, in any way, could modifications to that passed-by-value reference change the underlying object?

How to mark a method as obsolete or deprecated?

With ObsoleteAttribute you can to show the deprecated method. Obsolete attribute has three constructor:

  1. [Obsolete]: is a no parameter constructor and is a default using this attribute.
  2. [Obsolete(string message)]: in this format you can get message of why this method is deprecated.
  3. [Obsolete(string message, bool error)]: in this format message is very explicit but error means, in compilation time, compiler must be showing error and cause to fail compiling or not.

enter image description here

How to break a while loop from an if condition inside the while loop?

The break keyword does exactly that. Here is a contrived example:

public static void main(String[] args) {
  int i = 0;
  while (i++ < 10) {
    if (i == 5) break;
  System.out.println(i); //prints 5

If you were actually using nested loops, you would be able to use labels.

How to use hex color values

extension UIColor {
    public convenience init?(hex: String) {
        let r, g, b, a: CGFloat

        if hex.hasPrefix("#") {
            let start = hex.index(hex.startIndex, offsetBy: 1)
            let hexColor = String(hex[start...])

            if hexColor.count == 8 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
                    g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
                    b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
                    a = CGFloat(hexNumber & 0x000000ff) / 255

                    self.init(red: r, green: g, blue: b, alpha: a)

        return nil


let white = UIColor(hex: "#ffffff")

What is the difference between H.264 video and MPEG-4 video?

H.264 is a new standard for video compression which has more advanced compression methods than the basic MPEG-4 compression. One of the advantages of H.264 is the high compression rate. It is about 1.5 to 2 times more efficient than MPEG-4 encoding. This high compression rate makes it possible to record more information on the same hard disk.
The image quality is also better and playback is more fluent than with basic MPEG-4 compression. The most interesting feature however is the lower bit-rate required for network transmission.
So the 3 main advantages of H.264 over MPEG-4 compression are:
- Small file size for longer recording time and better network transmission.
- Fluent and better video quality for real time playback
- More efficient mobile surveillance application

H264 is now enshrined in MPEG4 as part 10 also known as AVC

Refer to:

Hope this helps.

What is AndroidX?

I got to know about AndroidX from this Android Dev Summit video. The summarization is -

  1. No more support library: The android support library will be never maintained by Google under the support library namespace. So if you want to find fixes of a bug in support library you must have to migrate your project in AndroidX
  2. Better package management: For standardized and independent versioning.Because previous support library versioning was too confusing. It will release you the pain of “All libraries must use the exact same version specification” message.
  3. Other God libraries have migrated to AndroidX: Google play services, Firebase, Mockito 2, etc are migrated to AndroidX.
  4. New libraries will be published using AndroidX artifact: All the libraries will be in the AndroidX namespace like Android Jetpack

comparing 2 strings alphabetically for sorting purposes

Lets look at some test cases - try running the following expressions in your JS console:

"a" < "b"

"aa" < "ab"

"aaa" < "aab"

All return true.

JavaScript compares strings character by character and "a" comes before "b" in the alphabet - hence less than.

In your case it works like so -

1 . "a?aaa" < "?a?b"

compares the first two "a" characters - all equal, lets move to the next character.

2 . "a?a??aa" < "a?b??"

compares the second characters "a" against "b" - whoop! "a" comes before "b". Returns true.

Installing cmake with home-brew

  1. Download the latest CMake Mac binary distribution here: (current latest is:

  2. Double click the downloaded .dmg file to install it. In the window that pops up, drag the CMake icon into the Application folder.

  3. Add this line to your .bashrc file: PATH="/Applications/":"$PATH"

  4. Reload your .bashrc file: source ~/.bashrc

  5. Verify the latest cmake version is installed: cmake --version

  6. You can launch the CMake GUI by clicking on LaunchPad and typing cmake. Click on the CMake icon that appears.

"unexpected token import" in Nodejs5 and babel?

if you use the preset for react-native it accepts the import

npm i babel-preset-react-native --save-dev

and put it inside your .babelrc file

  "presets": ["react-native"]

in your project root directory

CSS pseudo elements in React

Inline styles cannot be used to target pseudo-classes or pseudo-elements. You need to use a stylesheet.

If you want to generate CSS dynamically, then the easiest way is to create a DOM element <style>.

<style dangerouslySetInnerHTML={{
  __html: [
     '.my-special-div:after {',
     '  content: "Hello";',
     '  position: absolute',
<div className='my-special-div'></div>

How does EL empty operator work in JSF?

From EL 2.2 specification (get the one below "Click here to download the spec for evaluation"):

1.10 Empty Operator - empty A

The empty operator is a prefix operator that can be used to determine if a value is null or empty.

To evaluate empty A

  • If A is null, return true
  • Otherwise, if A is the empty string, then return true
  • Otherwise, if A is an empty array, then return true
  • Otherwise, if A is an empty Map, return true
  • Otherwise, if A is an empty Collection, return true
  • Otherwise return false

So, considering the interfaces, it works on Collection and Map only. In your case, I think Collection is the best option. Or, if it's a Javabean-like object, then Map. Either way, under the covers, the isEmpty() method is used for the actual check. On interface methods which you can't or don't want to implement, you could throw UnsupportedOperationException.

How to get memory available or used in C#

In addition to @JesperFyhrKnudsen's answer and @MathiasLykkegaardLorenzen's comment, you'd better dispose the returned Process after using it.

So, In order to dispose the Process, you could wrap it in a using scope or calling Dispose on the returned process (proc variable).

  1. using scope:

    var memory = 0.0;
    using (Process proc = Process.GetCurrentProcess())
        // The proc.PrivateMemorySize64 will returns the private memory usage in byte.
        // Would like to Convert it to Megabyte? divide it by 2^20
           memory = proc.PrivateMemorySize64 / (1024*1024);
  2. Or Dispose method:

    var memory = 0.0;
    Process proc = Process.GetCurrentProcess();
    memory = Math.Round(proc.PrivateMemorySize64 / (1024*1024), 2);

Now you could use the memory variable which is converted to Megabyte.

Batch Renaming of Files in a Directory

If you would like to modify file names in an editor (such as vim), the click library comes with the command click.edit(), which can be used to receive user input from an editor. Here is an example of how it can be used to refactor files in a directory.

import click
from pathlib import Path

# current directory
direc_to_refactor = Path(".")

# list of old file paths
old_paths = list(direc_to_refactor.iterdir())

# list of old file names
old_names = [str( for p in old_paths]

# modify old file names in an editor,
# and store them in a list of new file names
new_names = click.edit("\n".join(old_names)).split("\n")

# refactor the old file names
for i in range(len(old_paths)):
    old_paths[i].replace(direc_to_refactor / new_names[i])

I wrote a command line application that uses the same technique, but that reduces the volatility of this script, and comes with more options, such as recursive refactoring. Here is the link to the github page. This is useful if you like command line applications, and are interested in making some quick edits to file names. (My application is similar to the "bulkrename" command found in ranger).

Adobe Reader Command Line Reference

Having /A without additional parameters other than the filename didn't work for me, but the following code worked fine with /n

string sfile = @".\help\delta-pqca-400-100-300-fc4-user-manual.pdf";
Process myProcess = new Process();
myProcess.StartInfo.FileName = "AcroRd32.exe"; 
myProcess.StartInfo.Arguments = " /n " + "\"" + sfile + "\"";

Eliminating duplicate values based on only one column of the table

I solve such queries using this pattern:

WHERE t.field=(
  SELECT MAX(t.field) 
  FROM t AS t0 
  WHERE t.group_column1=t0.group_column1
    AND t.group_column2=t0.group_column2 ...)

That is it will select records where the value of a field is at its max value. To apply it to your query I used the common table expression so that I don't have to repeat the JOIN twice:

WITH site_history AS (
  SELECT sites.siteName, sites.siteIP,
  FROM sites
  JOIN history USING (siteName)
FROM site_history h
WHERE date=(
  SELECT MAX(date) 
  FROM site_history h0 
  WHERE h.siteName=h0.siteName)
ORDER BY siteName

It's important to note that it works only if the field we're calculating the maximum for is unique. In your example the date field should be unique for each siteName, that is if the IP can't be changed multiple times per millisecond. In my experience this is commonly the case otherwise you don't know which record is the newest anyway. If the history table has an unique index for (site, date), this query is also very fast, index range scan on the history table scanning just the first item can be used.

How to compare two vectors for equality element by element in C++?

Your code (vector1 == vector2) is correct C++ syntax. There is an == operator for vectors.

If you want to compare short vector with a portion of a longer vector, you can use theequal() operator for vectors. (documentation here)

Here's an example:

using namespace std;

if( equal(vector1.begin(), vector1.end(), vector2.begin()) )

adding classpath in linux

Important difference between setting Classpath in Windows and Linux is path separator which is ";" (semi-colon) in Windows and ":" (colon) in Linux. Also %PATH% is used to represent value of existing path variable in Windows while ${PATH} is used for same purpose in Linux (in the bash shell). Here is the way to setup classpath in Linux:

export CLASSPATH=${CLASSPATH}:/new/path

but as such Classpath is very tricky and you may wonder why your program is not working even after setting correct Classpath. Things to note:

  1. -cp options overrides CLASSPATH environment variable.
  2. Classpath defined in Manifest file overrides both -cp and CLASSPATH envorinment variable.

Reference: How Classpath works in Java.

jQuery click event on radio button doesn't get fired

There are a couple of things wrong in this code:

  1. You're using <input> the wrong way. You should use a <label> if you want to make the text behind it clickable.
  2. It's setting the enabled attribute, which does not exist. Use disabled instead.
  3. If it would be an attribute, it's value should not be false, use disabled="disabled" or simply disabled without a value.
  4. If checking for someone clicking on a form event that will CHANGE it's value (like check-boxes and radio-buttons), use .change() instead.

I'm not sure what your code is supposed to do. My guess is that you want to disable the input field with class roomNumber once someone selects "Walk in" (and possibly re-enable when deselected). If so, try this code:


<form class="type">
        <input type="radio" name="type" checked="checked" id="guest" value="guest" />
        <label for="guest">In House</label>
        <input type="radio" name="type" id="walk_in" value="walk_in" />
        <label for="walk_in">Walk in</label>
        <input type="text" name="roomnumber" class="roomNumber" value="12345" />


$("form input:radio").change(function () {
    if ($(this).val() == "walk_in") {
        // Disable your roomnumber element here
        $('.roomNumber').attr('disabled', 'disabled');
    } else {
        // Re-enable here I guess

I created a fiddle here:

MySQL Error 1264: out of range value for column


Make sure your AUTO_INCREMENT is not out of range. In that case, set a new value for it with:

ALTER TABLE table_name AUTO_INCREMENT=100 -- Change 100 to the desired number


AUTO_INCREMENT can contain a number that is bigger than the maximum value allowed by the datatype. This can happen if you filled up a table that you emptied afterward but the AUTO_INCREMENT stayed the same, but there might be different reasons as well. In this case a new entry's id would be out of range.


If this is the cause of your problem, you can fix it by setting AUTO_INCREMENT to one bigger than the latest row's id. So if your latest row's id is 100 then:


If you would like to check AUTO_INCREMENT's current value, use this command:

AND   TABLE_NAME   = 'TableName';

Javascript ES6/ES5 find in array and change

Whereas most of the existing answers are great, I would like to include an answer using a traditional for loop, which should also be considered here. The OP requests an answer which is ES5/ES6 compatible, and the traditional for loop applies :)

The problem with using array functions in this scenario, is that they don't mutate objects, but in this case, mutation is a requirement. The performance gain of using a traditional for loop is just a (huge) bonus.

const findThis = 2;
const items = [{id:1, ...}, {id:2, ...}, {id:3, ...}];

for (let i = 0, l = items.length; i < l; ++i) {
  if (items[i].id === findThis) {
    items[i].iAmChanged = true;

Although I am a great fan of array functions, don't let them be the only tool in your toolbox. If the purpose is mutating the array, they are not the best fit.

Simple way to encode a string according to a password?

Here's an implementation of URL Safe encryption and Decryption using AES(PyCrypto) and base64.

import base64
from Crypto import Random
from Crypto.Cipher import AES

AKEY = b'mysixteenbytekey' # AES key must be either 16, 24, or 32 bytes long

iv =

def encode(message):
    obj =, AES.MODE_CFB, iv)
    return base64.urlsafe_b64encode(obj.encrypt(message))

def decode(cipher):
    obj2 =, AES.MODE_CFB, iv)
    return obj2.decrypt(base64.urlsafe_b64decode(cipher))

If you face some issue like this (TypeError: character mapping must return integer, None or unicode) use str(cipher) while decoding as follows:

return obj2.decrypt(base64.urlsafe_b64decode(str(cipher)))


In [13]: encode(b"Hello World")
Out[13]: b'67jjg-8_RyaJ-28='

In [14]: %timeit encode("Hello World")
100000 loops, best of 3: 13.9 µs per loop

In [15]: decode(b'67jjg-8_RyaJ-28=')
Out[15]: b'Hello World'

In [16]: %timeit decode(b'67jjg-8_RyaJ-28=')
100000 loops, best of 3: 15.2 µs per loop

Composer install error - requires ext_curl when it's actually enabled

For anyone who encounters this issue on Windows i couldn't find my answer on google at all. I just tried running composer require ext-curl and this worked. Alternatively add the following in your composer.json file:

"require": {
"ext-curl": "^7.3"

Difference between Inheritance and Composition

Inheritence means reusing the complete functionality of a class, Here my class have to use all the methods of the super class and my class will be titely coupled with the super class and code will be duplicated in both the classes in case of inheritence.

But we can overcome from all these problem when we use composition to talk with another class . composition is declaring an attribute of another class into my class to which we want to talk. and what functionality we want from that class we can get by using that attribute.

Get folder up one level

Also you can use dirname(__DIR__, $level) for access any folding level without traversing

Best way to randomize an array with .NET

private ArrayList ShuffleArrayList(ArrayList source)
    ArrayList sortedList = new ArrayList();
    Random generator = new Random();

    while (source.Count > 0)
        int position = generator.Next(source.Count);
    return sortedList;

Refused to display 'url' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'

I faced the same error when displaying YouTube links. For example:

I replaced watch?v= with embed/ so the valid link will be:

It works well.

Try to apply the same rule on your case.

plot legends without border and with white background

Use option bty = "n" in legend to remove the box around the legend. For example:

legend(1, 5,
       "This legend text should not be disturbed by the dotted grey lines,\nbut the plotted dots should still be visible",
       bty = "n")

glob exclude pattern

How about skipping the particular file while iterating over all the files in the folder! Below code would skip all excel files that start with 'eph'

import glob
import re
for file in glob.glob('*.xlsx'):
    if re.match('eph.*\.xlsx',file):
        #do your stuff here

This way you can use more complex regex patterns to include/exclude a particular set of files in a folder.

View RDD contents in Python Spark?

If you want to see the contents of RDD then yes collect is one option, but it fetches all the data to driver so there can be a problem

<>.take(<num of elements you want to fetch>)

Better if you want to see just a sample

Running foreach and trying to print, I dont recommend this because if you are running this on cluster then the print logs would be local to the executor and it would print for the data accessible to that executor. print statement is not changing the state hence it is not logically wrong. To get all the logs you will have to do something like

foreach print

But this may result in job failure as collecting all the data on driver may crash it. I would suggest using take command or if u want to analyze it then use sample collect on driver or write to file and then analyze it.

ReactJS - .JS vs .JSX

JSX isn't standard JavaScript, based to Airbnb style guide 'eslint' could consider this pattern

// filename: MyComponent.js
function MyComponent() {
  return <div />;

as a warning, if you named your file MyComponent.jsx it will pass , unless if you edit the eslint rule you can check the style guide here

Open web in new tab Selenium + Python

The other solutions do not work for chrome driver v83.

Instead, it works as follows, suppose there is only 1 opening tab:


If there are already more than 1 opening tabs, you should first get the index of the last newly-created tab and switch to the tab before calling the url (Credit to tylerl) :


If statement within Where clause

CASE might help you out:

SELECT t.first_name,
  FROM employeetable t
 WHERE t.status = (CASE WHEN status_flag = STATUS_ACTIVE THEN 'A'
                        WHEN status_flag = STATUS_INACTIVE THEN 'T'
                        ELSE null END)
   AND t.business_unit = (CASE WHEN source_flag = SOURCE_FUNCTION THEN 'production'
                               WHEN source_flag = SOURCE_USER THEN 'users'
                               ELSE null END)
   AND t.first_name LIKE firstname
   AND t.last_name LIKE lastname
   AND t.employid LIKE employeeid;

The CASE statement evaluates multiple conditions to produce a single value. So, in the first usage, I check the value of status_flag, returning 'A', 'T' or null depending on what it's value is, and compare that to t.status. I do the same for the business_unit column with a second CASE statement.

How to sort Map values by key in Java?

List<String> list = new ArrayList<String>();
Map<String, String> map = new HashMap<String, String>();
for (String str : map.keySet()) {
for (String str : list) {

Access Denied for User 'root'@'localhost' (using password: YES) - No Privileges?

I did this-

sudo mysql -p

then i gave password for my root account(password that we use for sudo)then it asked to enter password and i gave password for mysql terminal(new password).

Bootstrap 3 : Vertically Center Navigation Links when Logo Increasing The Height of Navbar

I actually ended up with something like this to allow for the navbar collapse.

@media (min-width: 768px) { //set this to wherever the navbar collapse executes
  .navbar-nav > li > a{
    line-height: 7em; //set this height to the height of the logo.

Connecting client to server using

You need to make sure that you add forward slash before your link to

<script src="/"></script>

Then in the view/controller just do:

var socket = io.connect()

That should solve your problem.

Using bootstrap with bower

You have install nodeJs on your system in order to execute npm commands. Once npm is properly working you can visit There you will find complete documentation on this topic. You will find a command $ npm install bower. this will install bower on your machine. After installing bower you can install Bootstrap easily.

Here is a video tutorial on that

How do I change JPanel inside a JFrame on the fly?

The other individuals answered the question. I want to suggest you use a JTabbedPane instead of replacing content. As a general rule, it is bad to have visual elements of your application disappear or be replaced by other content. Certainly there are exceptions to every rule, and only you and your user community can decide the best approach.

How do I speed up the gwt compiler?

For GWT 2.x I just discovered that if you use

<set-property name="user.agent" value="ie6"/>
<extend-property values="ie8,gecko1_8" name="user.agent"/>

You can even specify more than one permutation.

How to change the default collation of a table?

may need to change the SCHEMA not only table

ALTER SCHEMA `<database name>`  DEFAULT CHARACTER SET utf8mb4  DEFAULT COLLATE utf8mb4_unicode_ci (as Rich said - utf8mb4);

(mariaDB 10)

Disable cache for some images

i had this problem and overcoming like this.

var newtags='<div class="addedimage"><h5>preview image</h5><img src="'+one+'?nocache='+Math.floor(Math.random() * 1000)+'"></div>';

How can I do width = 100% - 100px in CSS?

You can look into using LESS, which is a JavaScript file that pre-processes your CSS so you can include logic and variables into your CSS. So for your example, in LESS you would write width: 100% - 100px; to achieve exactly what you wanted :)

Is there an XSLT name-of element?

<xsl:for-each select="person">
  <xsl:for-each select="*">
    <xsl:value-of select="local-name()"/> : <xsl:value-of select="."/>

Docker compose, running containers in net:host

Those documents are outdated. I'm guessing the 1.6 in the URL is for Docker 1.6, not Compose 1.6. Check out the correct syntax here: You are looking for network_mode when using the v2 YAML format.

change html text from link with jquery

You have to use the jquery's text() function. What it does is:

Get the combined text contents of all matched elements.

The result is a string that contains the combined text contents of all matched elements. This method works on both HTML and XML documents. Cannot be used on input elements. For input field text use the val attribute.

For example:

Find the text in the first paragraph (stripping out the html), then set the html of the last paragraph to show it is just text (the bold is gone).

var str = $("p:first").text();

Test Paragraph.

Test Paragraph.

With your markup you have to do:

$('a#a_tbnotesverbergen').text('new text');

and it will result in

<a id="a_tbnotesverbergen" href="#nothing">new text</a>

Query to display all tablespaces in a database and datafiles

SELECT a.file_name,
       substr(A.tablespace_name,1,14) tablespace_name,
       trunc(decode(A.autoextensible,'YES',,'NO', free_mb,
       trunc(a.bytes/1024/1024) allocated_mb,
       trunc(A.MAXSIZE/1024/1024) capacity,
       a.autoextensible ae
     SELECT file_id, file_name,
            decode(autoextensible,'YES',maxbytes,bytes) maxsize
     FROM   dba_data_files
     GROUP BY file_id, file_name,
     ) a,
     (SELECT file_id,
             sum(bytes) free
      FROM   dba_free_space
      GROUP BY file_id,
      ) b
WHERE a.file_id=b.file_id(+)
AND A.tablespace_name=b.tablespace_name(+)
ORDER BY A.tablespace_name ASC; 

How to speed up insertion performance in PostgreSQL

Use COPY table TO ... WITH BINARY which is according to the documentation is "somewhat faster than the text and CSV formats." Only do this if you have millions of rows to insert, and if you are comfortable with binary data.

Here is an example recipe in Python, using psycopg2 with binary input.

How to iterate through property names of Javascript object?

In JavaScript 1.8.5, Object.getOwnPropertyNames returns an array of all properties found directly upon a given object.

Object.getOwnPropertyNames ( obj )

and another method Object.keys, which returns an array containing the names of all of the given object's own enumerable properties.

Object.keys( obj )

I used forEach to list values and keys in obj, same as for (var key in obj) ..

Object.keys(obj).forEach(function (key) {
      console.log( key , obj[key] );

This all are new features in ECMAScript , the mothods getOwnPropertyNames, keys won't supports old browser's.

Python: Number of rows affected by cursor.execute("SELECT ...)

In my opinion, the simplest way to get the amount of selected rows is the following:

The cursor object returns a list with the results when using the fetch commands (fetchall(), fetchone(), fetchmany()). To get the selected rows just print the length of this list. But it just makes sense for fetchall(). ;-)


print len(cursor.fetchall) 

Is there a way to detect if an image is blurry?

Answers above elucidated many things, but I think it is useful to make a conceptual distinction.

What if you take a perfectly on-focus picture of a blurred image?

The blurring detection problem is only well posed when you have a reference. If you need to design, e.g., an auto-focus system, you compare a sequence of images taken with different degrees of blurring, or smoothing, and you try to find the point of minimum blurring within this set. I other words you need to cross reference the various images using one of the techniques illustrated above (basically--with various possible levels of refinement in the approach--looking for the one image with the highest high-frequency content).

Is it possible to use raw SQL within a Spring Repository

YES, You can do this on bellow ways:

1. By CrudRepository (Projection)

Spring Data Repositories usually return the domain model when using query methods. However, sometimes, you may need to alter the view of that model for various reasons.

Suppose your entity is like this :

    import javax.persistence.*;
    import java.math.BigDecimal;

    @Table(name = "USER_INFO_TEST")
    public class UserInfoTest {
        private int id;
        private String name;
        private String rollNo;

        public UserInfoTest() {

        public UserInfoTest(int id, String name) { = id; = name;

        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "ID", nullable = false, precision = 0)
        public int getId() {
            return id;

        public void setId(int id) {
   = id;

        @Column(name = "name", nullable = true)
        public String getName() {
            return name;

        public void setName(String name) {
   = name;

        @Column(name = "roll_no", nullable = true)
        public String getRollNo() {
            return rollNo;

        public void setRollNo(String rollNo) {
            this.rollNo = rollNo;

Now your Projection class is like bellow. It can those fields that you needed.

public interface IUserProjection {
     int getId();
     String getName();
     String getRollNo();

And Your Data Access Object(Dao) is like bellow :


import java.util.ArrayList;

public interface UserInfoTestDao extends CrudRepository<UserInfoTest,Integer> {
    @Query(value = "select id,name,roll_no from USER_INFO_TEST where rollNo = ?1", nativeQuery = true)
    ArrayList<IUserProjection> findUserUsingRollNo(String rollNo);

Now ArrayList<IUserProjection> findUserUsingRollNo(String rollNo) will give you the list of user.

2. Using EntityManager

Suppose your query is "select id,name from users where roll_no = 1001".

Here query will return a object with id and name column. Your Response class is like bellow:

Your Response class is like:

public class UserObject{
        int id;
        String name;
        String rollNo;

        public UserObject(Object[] columns) {
   = (columns[0] != null)?((BigDecimal)columns[0]).intValue():0;
   = (String) columns[1];

        public int getId() {
            return id;

        public void setId(int id) {
   = id;

        public String getName() {
            return name;

        public void setName(String name) {
   = name;

        public String getRollNo() {
            return rollNo;

        public void setRollNo(String rollNo) {
            this.rollNo = rollNo;

here UserObject constructor will get a Object Array and set data with object.

public UserObject(Object[] columns) {
   = (columns[0] != null)?((BigDecimal)columns[0]).intValue():0;
   = (String) columns[1];

Your query executing function is like bellow :

public UserObject getUserByRoll(EntityManager entityManager,String rollNo) {

        String queryStr = "select id,name from users where roll_no = ?1";
        try {
            Query query = entityManager.createNativeQuery(queryStr);
            query.setParameter(1, rollNo);

            return new UserObject((Object[]) query.getSingleResult());
        } catch (Exception e) {
            throw e;

Here you have to import bellow packages:

import javax.persistence.Query;
import javax.persistence.EntityManager;

Now your main class, you have to call this function. First get EntityManager and call this getUserByRoll(EntityManager entityManager,String rollNo) function. Calling procedure is given bellow:

Here is the Imports

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

get EntityManager from this way:

private EntityManager entityManager;

UserObject userObject = getUserByRoll(entityManager,"1001");

Now you have data in this userObject.


query.getSingleResult() return a object array. You have to maintain the column position and data type with query column position.

select id,name from users where roll_no = 1001 

query return a array and it's [0] --> id and [1] -> name.

More info visit this thread and this Thread

Thanks :)

Dynamically adding HTML form field using jQuery

What seems to be confusing this thread is the difference between:

$('.selector').append("<input type='text'/>"); 

Which appends the target element as a child of the .selector.


$("<input type='text' />").appendTo('.selector');

Which appends the target element as a child of the .selector.

Note how the position of the target element & the .selector change when using the different methods.

What you want to do is this:

$(function() {

  // append input control at start of form
  $("<input type='text' value='' />")
     .attr("id", "myfieldid")
     .attr("name", "myfieldid")

  // OR

  // append input control at end of form
  $("<input type='text' value='' />")
     .attr("id", "myfieldid")
     .attr("name", "myfieldid")

  // OR

  // see .after() or .before() in the library


R Not in subset

The expression df1$id %in% idNums1 produces a logical vector. To negate it, you need to negate the whole vector:

!(df1$id %in% idNums1)

Does Java have something like C#'s ref and out keywords?

java has no standard way of doing it. Most swaps will be made on the list that is packaged in the class. but there is an unofficial way to do it:

package Example;

import java.lang.reflect.Field;
import java.util.logging.Level;
import java.util.logging.Logger;

 public class Test{

private static <T> void SetValue(T obj,T value){
    try {
        Field f = obj.getClass().getDeclaredField("value");
        } catch (IllegalAccessException | IllegalArgumentException | 
            NoSuchFieldException | SecurityException ex) {
       null, ex);
private  static  void permutation(Integer a,Integer b){
    Integer tmp = new Integer(a);
    SetValue(a, b);
    SetValue(b, tmp);
 private  static  void permutation(String a,String b){
    char[] tmp = a.toCharArray();
    SetValue(a, b.toCharArray());
    SetValue(b, tmp);
public static void main(String[] args) {
        Integer d = 9;
        Integer e = 8;
        HoanVi(d, e);
        System.out.println(d+" "+ e);
        String d = "tai nguyen";
        String e = "Thai nguyen";
        permutation(d, e);
        System.out.println(d+" "+ e);


How to validate phone number using PHP?

Since phone numbers must conform to a pattern, you can use regular expressions to match the entered phone number against the pattern you define in regexp.

php has both ereg and preg_match() functions. I'd suggest using preg_match() as there's more documentation for this style of regex.

An example

$phone = '000-0000-0000';

if(preg_match("/^[0-9]{3}-[0-9]{4}-[0-9]{4}$/", $phone)) {
  // $phone is valid

Pytorch reshape tensor dimension

There are multiple ways of reshaping a PyTorch tensor. You can apply these methods on a tensor of any dimensionality.

Let's start with a 2-dimensional 2 x 3 tensor:

x = torch.Tensor(2, 3)
# torch.Size([2, 3])

To add some robustness to this problem, let's reshape the 2 x 3 tensor by adding a new dimension at the front and another dimension in the middle, producing a 1 x 2 x 1 x 3 tensor.

Approach 1: add dimension with None

Use NumPy-style insertion of None (aka np.newaxis) to add dimensions anywhere you want. See here.

# torch.Size([2, 3])

y = x[None, :, None, :] # Add new dimensions at positions 0 and 2.
# torch.Size([1, 2, 1, 3])

Approach 2: unsqueeze

Use torch.Tensor.unsqueeze(i) (a.k.a. torch.unsqueeze(tensor, i) or the in-place version unsqueeze_()) to add a new dimension at the i'th dimension. The returned tensor shares the same data as the original tensor. In this example, we can use unqueeze() twice to add the two new dimensions.

# torch.Size([2, 3])

# Use unsqueeze twice.
y = x.unsqueeze(0) # Add new dimension at position 0
# torch.Size([1, 2, 3])

y = y.unsqueeze(2) # Add new dimension at position 2
# torch.Size([1, 2, 1, 3])

In practice with PyTorch, adding an extra dimension for the batch may be important, so you may often see unsqueeze(0).

Approach 3: view

Use torch.Tensor.view(*shape) to specify all the dimensions. The returned tensor shares the same data as the original tensor.

# torch.Size([2, 3])

y = x.view(1, 2, 1, 3)
# torch.Size([1, 2, 1, 3])

Approach 4: reshape

Use torch.Tensor.reshape(*shape) (aka torch.reshape(tensor, shapetuple)) to specify all the dimensions. If the original data is contiguous and has the same stride, the returned tensor will be a view of input (sharing the same data), otherwise it will be a copy. This function is similar to the NumPy reshape() function in that it lets you define all the dimensions and can return either a view or a copy.

# torch.Size([2, 3])

y = x.reshape(1, 2, 1, 3)
# torch.Size([1, 2, 1, 3])

Furthermore, from the O'Reilly 2019 book Programming PyTorch for Deep Learning, the author writes:

Now you might wonder what the difference is between view() and reshape(). The answer is that view() operates as a view on the original tensor, so if the underlying data is changed, the view will change too (and vice versa). However, view() can throw errors if the required view is not contiguous; that is, it doesn’t share the same block of memory it would occupy if a new tensor of the required shape was created from scratch. If this happens, you have to call tensor.contiguous() before you can use view(). However, reshape() does all that behind the scenes, so in general, I recommend using reshape() rather than view().

Approach 5: resize_

Use the in-place function torch.Tensor.resize_(*sizes) to modify the original tensor. The documentation states:

WARNING. This is a low-level method. The storage is reinterpreted as C-contiguous, ignoring the current strides (unless the target size equals the current size, in which case the tensor is left unchanged). For most purposes, you will instead want to use view(), which checks for contiguity, or reshape(), which copies data if needed. To change the size in-place with custom strides, see set_().

# torch.Size([2, 3])

x.resize_(1, 2, 1, 3)
# torch.Size([1, 2, 1, 3])

My observations

If you want to add just one dimension (e.g. to add a 0th dimension for the batch), then use unsqueeze(0). If you want to totally change the dimensionality, use reshape().

See also:

What's the difference between reshape and view in pytorch?

What is the difference between view() and unsqueeze()?

In PyTorch 0.4, is it recommended to use reshape than view when it is possible?

How to create a checkbox with a clickable label?

It works too :

    <label for="male"><input type="checkbox" name="male" id="male" />Male</label><br />
    <label for="female"><input type="checkbox" name="female" id="female" />Female</label>

Checking for directory and file write permissions in .NET

Directory.GetAccessControl(path) does what you are asking for.

public static bool HasWritePermissionOnDir(string path)
    var writeAllow = false;
    var writeDeny = false;
    var accessControlList = Directory.GetAccessControl(path);
    if (accessControlList == null)
        return false;
    var accessRules = accessControlList.GetAccessRules(true, true, 
    if (accessRules ==null)
        return false;

    foreach (FileSystemAccessRule rule in accessRules)
        if ((FileSystemRights.Write & rule.FileSystemRights) != FileSystemRights.Write) 

        if (rule.AccessControlType == AccessControlType.Allow)
            writeAllow = true;
        else if (rule.AccessControlType == AccessControlType.Deny)
            writeDeny = true;

    return writeAllow && !writeDeny;

(FileSystemRights.Write & rights) == FileSystemRights.Write is using something called "Flags" btw which if you don't know what it is you should really read up on :)

Returning unique_ptr from functions

This is in no way specific to std::unique_ptr, but applies to any class that is movable. It's guaranteed by the language rules since you are returning by value. The compiler tries to elide copies, invokes a move constructor if it can't remove copies, calls a copy constructor if it can't move, and fails to compile if it can't copy.

If you had a function that accepts std::unique_ptr as an argument you wouldn't be able to pass p to it. You would have to explicitly invoke move constructor, but in this case you shouldn't use variable p after the call to bar().

void bar(std::unique_ptr<int> p)
    // ...

int main()
    unique_ptr<int> p = foo();
    bar(p); // error, can't implicitly invoke move constructor on lvalue
    bar(std::move(p)); // OK but don't use p afterwards
    return 0;

How to convert a string to a date in sybase

Several ways to accomplish that but be aware that your DB date_format option & date_order option settings could affect the incoming format:

   cast('2008-09-16' as date)
from dummy;

How to return 2 values from a Java method?

Java does not support multi-value returns. Return an array of values.

// Function code
public static int[] something(){
    int number1 = 1;
    int number2 = 2;
    return new int[] {number1, number2};

// Main class code
public static void main(String[] args) {
  int result[] = something();
  System.out.println(result[0] + result[1]);

Good way to encapsulate Integer.parseInt()

You could roll your own, but it's just as easy to use commons lang's StringUtils.isNumeric() method. It uses Character.isDigit() to iterate over each character in the String.

What's an easy way to read random line from a file in Unix command line?

Here is what I discovery since my Mac OS doesn't use all the easy answers. I used the jot command to generate a number since the $RANDOM variable solutions seems not to be very random in my test. When testing my solution I had a wide variance in the solutions provided in the output.

  RANDOM1=`jot -r 1 1 235886`
   #range of jot ( 1 235886 ) found from earlier wc -w /usr/share/dict/web2
   echo $RANDOM1
   head -n $RANDOM1 /usr/share/dict/web2 | tail -n 1

The echo of the variable is to get a visual of the generated random number.

How should I escape commas and speech marks in CSV files so they work in Excel?

Below are the rules if you believe it's random. A utility function can be created on the basis of these rules.

  1. If the value contains a comma, newline or double quote, then the String value should be returned enclosed in double quotes.

  2. Any double quote characters in the value should be escaped with another double quote.

  3. If the value does not contain a comma, newline or double quote, then the String value should be returned unchanged.

Difference between map, applymap and apply methods in Pandas

My understanding:

From the function point of view:

If the function has variables that need to compare within a column/ row, use apply.

e.g.: lambda x: x.max()-x.mean().

If the function is to be applied to each element:

1> If a column/row is located, use apply

2> If apply to entire dataframe, use applymap

majority = lambda x : x > 17
df2['legal_drinker'] = df2['age'].apply(majority)

def times10(x):
  if type(x) is int:
    x *= 10 
  return x

SQL- Ignore case while searching for a string

See this similar question and answer to searching with case insensitivity - SQL server ignore case in a where expression

Try using something like:

FROM myTable 
WHERE COL_NAME COLLATE SQL_Latin1_General_CP1_CI_AS LIKE '%priceorder%'

What is the difference between a .cpp file and a .h file?

The C++ build system (compiler) knows no difference, so it's all one of conventions.

The convention is that .h files are declarations, and .cpp files are definitions.

That's why .h files are #included -- we include the declarations.

Docker - Container is not running

Here is what worked for me.

Get the container ID and restart.

docker ps -a --no-trunc 


docker restart ace7ca65e6e3fdb678d9cdfb33a7a165c510e65c3bc28fecb960ac993c37ef33

notifyDataSetChanged not working on RecyclerView

Clear your old viewmodel and set the new data to the adapter and call notifyDataSetChanged()

What's the fastest way of checking if a point is inside a polygon in python

Comparison of different methods

I found other methods to check if a point is inside a polygon (here). I tested two of them only (is_inside_sm and is_inside_postgis) and the results were the same as the other methods.

Thanks to @epifanio, I parallelized the codes and compared them with @epifanio and @user3274748 (ray_tracing_numpy) methods. Note that both methods had a bug so I fixed them as shown in their codes below.

One more thing that I found is that the code provided for creating a polygon does not generate a closed path np.linspace(0,2*np.pi,lenpoly)[:-1]. As a result, the codes provided in above GitHub repository may not work properly. So It's better to create a closed path (first and last points should be the same).


Method 1: parallelpointinpolygon

from numba import jit, njit
import numba
import numpy as np 

def pointinpolygon(x,y,poly):
    n = len(poly)
    inside = False
    p2x = 0.0
    p2y = 0.0
    xints = 0.0
    p1x,p1y = poly[0]
    for i in numba.prange(n+1):
        p2x,p2y = poly[i % n]
        if y > min(p1y,p2y):
            if y <= max(p1y,p2y):
                if x <= max(p1x,p2x):
                    if p1y != p2y:
                        xints = (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
                    if p1x == p2x or x <= xints:
                        inside = not inside
        p1x,p1y = p2x,p2y

    return inside

def parallelpointinpolygon(points, polygon):
    D = np.empty(len(points), dtype=numba.boolean) 
    for i in numba.prange(0, len(D)):   #<-- Fixed here, must start from zero
        D[i] = pointinpolygon(points[i,0], points[i,1], polygon)
    return D  

Method 2: ray_tracing_numpy_numba

def ray_tracing_numpy_numba(points,poly):
    x,y = points[:,0], points[:,1]
    n = len(poly)
    inside = np.zeros(len(x),np.bool_)
    p2x = 0.0
    p2y = 0.0
    p1x,p1y = poly[0]
    for i in range(n+1):
        p2x,p2y = poly[i % n]
        idx = np.nonzero((y > min(p1y,p2y)) & (y <= max(p1y,p2y)) & (x <= max(p1x,p2x)))[0]
        if len(idx):    # <-- Fixed here. If idx is null skip comparisons below.
            if p1y != p2y:
                xints = (y[idx]-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
            if p1x == p2x:
                inside[idx] = ~inside[idx]
                idxx = idx[x[idx] <= xints]
                inside[idxx] = ~inside[idxx]    

        p1x,p1y = p2x,p2y
    return inside 

Method 3: Matplotlib contains_points

path = mpltPath.Path(polygon,closed=True)  # <-- Very important to mention that the path 
                                           #     is closed (default is false)

Method 4: is_inside_sm (got it from here)

def is_inside_sm(polygon, point):
    length = len(polygon)-1
    dy2 = point[1] - polygon[0][1]
    intersections = 0
    ii = 0
    jj = 1

    while ii<length:
        dy  = dy2
        dy2 = point[1] - polygon[jj][1]

        # consider only lines which are not completely above/bellow/right from the point
        if dy*dy2 <= 0.0 and (point[0] >= polygon[ii][0] or point[0] >= polygon[jj][0]):

            # non-horizontal line
            if dy<0 or dy2<0:
                F = dy*(polygon[jj][0] - polygon[ii][0])/(dy-dy2) + polygon[ii][0]

                if point[0] > F: # if line is left from the point - the ray moving towards left, will intersect it
                    intersections += 1
                elif point[0] == F: # point on line
                    return 2

            # point on upper peak (dy2=dx2=0) or horizontal line (dy=dy2=0 and dx*dx2<=0)
            elif dy2==0 and (point[0]==polygon[jj][0] or (dy==0 and (point[0]-polygon[ii][0])*(point[0]-polygon[jj][0])<=0)):
                return 2

        ii = jj
        jj += 1

    #print 'intersections =', intersections
    return intersections & 1  

def is_inside_sm_parallel(points, polygon):
    ln = len(points)
    D = np.empty(ln, dtype=numba.boolean) 
    for i in numba.prange(ln):
        D[i] = is_inside_sm(polygon,points[i])
    return D  

Method 5: is_inside_postgis (got it from here)

def is_inside_postgis(polygon, point):
    length = len(polygon)
    intersections = 0

    dx2 = point[0] - polygon[0][0]
    dy2 = point[1] - polygon[0][1]
    ii = 0
    jj = 1

    while jj<length:
        dx  = dx2
        dy  = dy2
        dx2 = point[0] - polygon[jj][0]
        dy2 = point[1] - polygon[jj][1]

        F =(dx-dx2)*dy - dx*(dy-dy2);
        if 0.0==F and dx*dx2<=0 and dy*dy2<=0:
            return 2;

        if (dy>=0 and dy2<0) or (dy2>=0 and dy<0):
            if F > 0:
                intersections += 1
            elif F < 0:
                intersections -= 1

        ii = jj
        jj += 1

    #print 'intersections =', intersections
    return intersections != 0  

def is_inside_postgis_parallel(points, polygon):
    ln = len(points)
    D = np.empty(ln, dtype=numba.boolean) 
    for i in numba.prange(ln):
        D[i] = is_inside_postgis(polygon,points[i])
    return D  


enter image description here

Timing for 10 million points:

parallelpointinpolygon Elapsed time:      4.0122294425964355
Matplotlib contains_points Elapsed time: 14.117807388305664
ray_tracing_numpy_numba Elapsed time:     7.908452272415161
sm_parallel Elapsed time:                 0.7710440158843994
is_inside_postgis_parallel Elapsed time:  2.131121873855591

Here is the code.

import matplotlib.pyplot as plt
import matplotlib.path as mpltPath
from time import time
import numpy as np



for i in range(1, 10000002, 1000000): 
    lenpoly = 100
    polygon = [[np.sin(x)+0.5,np.cos(x)+0.5] for x in np.linspace(0,2*np.pi,lenpoly)]
    polygon = np.array(polygon)
    N = i
    points = np.random.uniform(-1.5, 1.5, size=(N, 2))
    #Method 1
    start_time = time()
    inside1=parallelpointinpolygon(points, polygon)

    # Method 2
    start_time = time()
    path = mpltPath.Path(polygon,closed=True)
    inside2 = path.contains_points(points)

    # Method 3
    start_time = time()

    # Method 4
    start_time = time()

    # Method 5
    start_time = time()

plt.xlabel("N points")
plt.ylabel("time (sec)")
plt.legend(loc = 'best')


The fastest algorithms are:

1- is_inside_sm_parallel

2- is_inside_postgis_parallel

3- parallelpointinpolygon (@epifanio)

Can Windows' built-in ZIP compression be scripted?

Yes, this can be scripted with VBScript. For example the following code can create a zip from a directory:

Dim fso, winShell, MyTarget, MySource, file
Set fso = CreateObject("Scripting.FileSystemObject")
Set winShell = createObject("shell.application")

MyTarget = Wscript.Arguments.Item(0)
MySource = Wscript.Arguments.Item(1)

Wscript.Echo "Adding " & MySource & " to " & MyTarget

'create a new clean zip archive
Set file = fso.CreateTextFile(MyTarget, True)
file.write("PK" & chr(5) & chr(6) & string(18,chr(0)))

winShell.NameSpace(MyTarget).CopyHere winShell.NameSpace(MySource).Items

do until winShell.namespace(MyTarget).items.count = winShell.namespace(MySource).items.count
    wscript.sleep 1000 

Set winShell = Nothing
Set fso = Nothing

You may also find helpful as it includes a full Unzip/Zip implementation in VBScript.

If you do a size check every 500 ms rather than a item count it works better for large files. Win 7 writes the file instantly although it's not finished compressing:

set fso=createobject("scripting.filesystemobject")
Set h=fso.getFile(DestZip)
    wscript.sleep 500
    max = h.size
loop while h.size > max 

Works great for huge amounts of log files.

Using Mysql WHERE IN clause in codeigniter

You can use sub query way of codeigniter to do this for this purpose you will have to hack codeigniter. like this
Go to system/database/DB_active_rec.php Remove public or protected keyword from these functions

public function _compile_select($select_override = FALSE)
public function _reset_select()

Now subquery writing in available And now here is your query with active record

$subQuery = $this->db->_compile_select();

// And now your main query
$this->db->where('code !=', 'B');

And the thing is done. Cheers!!!
Note : While using sub queries you must use


instead of


which runs the query.
Watch this too

How can I rewrite this SQL into CodeIgniter's Active Records?

Note : In Codeigntier 3 these functions are already public so you do not need to hack them.

(Excel) Conditional Formatting based on Adjacent Cell Value

I don't know if maybe it's a difference in Excel version but this question is 6 years old and the accepted answer didn't help me so this is what I figured out:

Under Conditional Formatting > Manage Rules:

  1. Make a new rule with "Use a formula to determine which cells to format"
  2. Make your rule, but put a dollar sign only in front of the letter: $A2<$B2
  3. Under "Applies to", Manually select the second column (It would not work for me if I changed the value in the box, it just kept snapping back to what was already there), so it looks like $B$2:$B$100 (assuming you have 100 rows)

This worked for me in Excel 2016.

Didn't find class ""?

I had the same problem in my (YouTube player project)... and the following solved the problem for me:

  1. Add this code into your build.gradle (module: app) inside defaultConfing:

    defaultConfig {
        multiDexEnabled = true
  2. Add this code into your build.gradle (module: app) inside dependencies:

    dependencies {
        compile ''
  3. Open AndroidManifest.xml and within application:


    or if you have your App class, extend it from MultiDexApplication like:

    public class MyApp extends MultiDexApplication {

And finally, I think you should have Android Support Repository downloaded, in the Extras in SDK Manager.

vue.js 'document.getElementById' shorthand

If you're attempting to get an element you can use Vue.util.query which is really just a wrapper around document.querySelector but at 14 characters vs 22 characters (respectively) it is technically shorter. It also has some error handling in case the element you're searching for doesn't exist.

There isn't any official documentation on Vue.util, but this is the entire source of the function:

function query(el) {
  if (typeof el === 'string') {
    var selector = el;
    el = document.querySelector(el);
    if (!el) {
      ({}).NODE_ENV !== 'production' && warn('Cannot find element: ' + selector);
  return el;

Repo link: Vue.util.query

font-weight is not working properly?

Most browsers don't fully support the numerical values for font-weight. Here's a good article about the problem, and even tough it's a little old, it does seem to be correct.

If you need something bolder then you might want to try using a different font that's bolder than your existing one. Naturally, you could probably adjust the font size for a similar effect.

AngularJs directive not updating another directive's scope

Just wondering why you are using 2 directives?

It seems like, in this case it would be more straightforward to have a controller as the parent - handle adding the data from your service to its $scope, and pass the model you need from there into your warrantyDirective.

Or for that matter, you could use 0 directives to achieve the same result. (ie. move all functionality out of the separate directives and into a single controller).

It doesn't look like you're doing any explicit DOM transformation here, so in this case, perhaps using 2 directives is overcomplicating things.

Alternatively, have a look at the Angular documentation for directives: The very last example at the bottom of the page explains how to wire up dependent directives.

Python Binomial Coefficient

Here is a function that recursively calculates the binomial coefficients using conditional expressions

def binomial(n,k):
    return 1 if k==0 else (0 if n==0 else binomial(n-1, k) + binomial(n-1, k-1))

Is the LIKE operator case-sensitive with MSSQL Server?

All this talk about collation seem a bit over-complicated. Why not just use something like:


Then your check is case insensitive whatever the collation

Authentication plugin 'caching_sha2_password' is not supported

I uninstalled mysql-connector (I installed following tutorial on w3schools tutorial) and installed mysql-connector-python instead. It worked.

Comparing user-inputted characters in C

Because comparison doesn't work that way. 'Y' || 'y' is a logical-or operator; it returns 1 (true) if either of its arguments is true. Since 'Y' and 'y' are both true, you're comparing *answer with 1.

What you want is if(*answer == 'Y' || *answer == 'y') or perhaps:

switch (*answer) {
  case 'Y':
  case 'y':
    /* Code for Y */
    /* Code for anything else */

What is a PDB file?

I had originally asked myself the question "Do I need a PDB file deployed to my customer's machine?", and after reading this post, decided to exclude the file.

Everything worked fine, until today, when I was trying to figure out why a message box containing an Exception.StackTrace was missing the file and line number information - necessary for troubleshooting the exception. I re-read this post and found the key nugget of information: that although the PDB is not necessary for the app to run, it is necessary for the file and line numbers to be present in the StackTrace string. I included the PDB file in the executable folder and now all is fine.

How to dynamically update labels captions in VBA form?

Use Controls object

For i = 1 To X
    Controls("Label" & i).Caption =  MySheet.Cells(i + 1, i).Value

Easiest way to mask characters in HTML(5) text input

Use this JavaScript.

$("#phone").inputmask({"mask": "(999) 999-9999"});

Trying to read cell 1,1 in spreadsheet using Google Script API

You have to first obtain the Range object. Also, getCell() will not return the value of the cell but instead will return a Range object of the cell. So, use something on the lines of

function email() {

// Opens SS by its ID

var ss = SpreadsheetApp.openById("0AgJjDgtUl5KddE5rR01NSFcxYTRnUHBCQ0stTXNMenc");

// Get the name of this SS

var name = ss.getName();  // Not necessary 

// Read cell 1,1 * Line below does't work *

// var data = Range.getCell(0, 0);
var sheet = ss.getSheetByName('Sheet1'); // or whatever is the name of the sheet 
var range = sheet.getRange(1,1); 
var data = range.getValue();


The hierarchy is Spreadsheet --> Sheet --> Range --> Cell.

Java foreach loop: for (Integer i : list) { ... }

The API does not support that directly. You can use the for(int i..) loop and count the elements or use subLists(0, size - 1) and handle the last element explicitly:

  if(x.isEmpty()) return;
  int last = x.size() - 1;
  for(Integer i : x.subList(0, last)) out.println(i);
  out.println("last " + x.get(last));

This is only useful if it does not introduce redundancy. It performs better than the counting version (after the subList overhead is amortized). (Just in case you cared after the boxing anyway).

How can I change the color of pagination dots of UIPageControl?

You could also use Three20 Library that contains a styleable PageControl and dozens of other helpful UI Controls and Abstractions.

How to prompt for user input and read command-line arguments

import six

if six.PY2:
    input = raw_input

print(input("What's your name? "))

How to combine two vectors into a data frame

Alt simplification of above:

cond <-c(1,2,3)
rating <-c(100,200,300)
df <- data.frame(cond, rating)
  cond rating
1    1    100
2    2    200
3    3    300

How to linebreak an svg text within javascript?

With the tspan solution, let's say you don't know in advance where to put your line breaks: you can use this nice function, that I found here:

That automatically does line breaks for long text svg for a given width in pixel.

function wrap(text, width) {
  text.each(function() {
    var text =,
        words = text.text().split(/\s+/).reverse(),
        line = [],
        lineNumber = 0,
        lineHeight = 1.1, // ems
        y = text.attr("y"),
        dy = parseFloat(text.attr("dy")),
        tspan = text.text(null).append("tspan").attr("x", 0).attr("y", y).attr("dy", dy + "em");
    while (word = words.pop()) {
      tspan.text(line.join(" "));
      if (tspan.node().getComputedTextLength() > width) {
        tspan.text(line.join(" "));
        line = [word];
        tspan = text.append("tspan").attr("x", 0).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);

Bootstrap css hides portion of container below navbar navbar-fixed-top

This is handled by adding some padding to the top of the <body>.

As per Bootstrap's documentation on .navbar-fixed-top, try out your own values or use our snippet below. Tip: By default, the navbar is 50px high.

  body {
    padding-top: 70px;

Also, take a look at the source for this example and open starter-template.css.

How to debug "ImagePullBackOff"?

I faced the similar situation and it turned out that with the actualisation of Docker Desktop I was signed out and after I signed back in all works fine again.

Handling file renames in git

Best thing is to try it for yourself.

mkdir test
cd test
git init
touch aaa.txt
git add .
git commit -a -m "New file"
mv aaa.txt bbb.txt
git add .
git status
git commit --dry-run -a

Now git status and git commit --dry-run -a shows two different results where git status shows bbb.txt as a new file/ aaa.txt is deleted, and the --dry-run commands shows the actual rename.

~/test$ git status

# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#   new file:   bbb.txt
# Changes not staged for commit:
#   (use "git add/rm <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#   deleted:    aaa.txt

/test$ git commit --dry-run -a

# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#   renamed:    aaa.txt -> bbb.txt

Now go ahead and do the check-in.

git commit -a -m "Rename"

Now you can see that the file is in fact renamed, and what's shown in git status is wrong.

Moral of the story: If you're not sure whether your file got renamed, issue a "git commit --dry-run -a". If its showing that the file is renamed, you're good to go.

How can I loop through a C++ map of maps?

With C++17 (or later), you can use the "structured bindings" feature, which lets you define multiple variables, with different names, using a single tuple/pair. Example:

for (const auto& [name, description] : planet_descriptions) {
    std::cout << "Planet " << name << ":\n" << description << "\n\n";

The original proposal (by luminaries Bjarne Stroustrup, Herb Sutter and Gabriel Dos Reis) is fun to read (and the suggested syntax is more intuitive IMHO); there's also the proposed wording for the standard which is boring to read but is closer to what will actually go in.