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Is it possible to see more than 65536 rows in Excel 2007?

I have found that the 65536 limit still applies to pivot tables, even in Excel 2007.

How do I set up Android Studio to work completely offline?

OK guys I finally overcame this problem. Here is the solution:

  1. Download for offline use.

  2. Paste it in the C:\Users\username\.gradle directory.

  3. Open Android Studio and click on the "Create New Project" option and you will not get this error any more while offline.

    You might get some other errors like this:

    Don't worry, just ignore it. Your project has been created.

  4. So now click on "Import Project" and go to the path C:\Users\username\AndroidStudioProjects and open your project and you are done.

How do you synchronise projects to GitHub with Android Studio?

This isn't specific to Android Studio, but a generic behaviour with Intellij's IDEA.

Go to: Preferences > Version Control > GitHub

Also note that you don't need the github integration: the standard git functions should be enough (VCS > Git, Tool Windows > Changes)

How to mark a build unstable in Jenkins when running shell scripts

I thought I would post another answer for people that might be looking for something similar.

In our build job we have cases where we would want the build to continue, but be marked as unstable. For ours it's relating to version numbers.

So, I wanted to set a condition on the build and set the build to unstable if that condition is met.

I used the Conditional step (single) option as a build step.

Then I used Execute system Groovy script as the build step that would run when that condition is met.

I used Groovy Command and set the script the following

import hudson.model.*

def build = Thread.currentThread().executable
build.@result = hudson.model.Result.UNSTABLE


That seems to work quite well.

I stumbled upon the solution here

Setting values on a copy of a slice from a DataFrame

This warning comes because your dataframe x is a copy of a slice. This is not easy to know why, but it has something to do with how you have come to the current state of it.

You can either create a proper dataframe out of x by doing

x = x.copy()

This will remove the warning, but it is not the proper way

You should be using the DataFrame.loc method, as the warning suggests, like this:

x.loc[:,'Mass32s'] = pandas.rolling_mean(x.Mass32, 5).shift(-2)

How to align an input tag to the center without specifying the width?

You can also use the tag, this works in divs and everything else:


This link will help you with the tag:

Why is the <center> tag deprecated in HTML?

git push vs git push origin <branchname>

First, you need to create your branch locally

git checkout -b your_branch

After that, you can work locally in your branch, when you are ready to share the branch, push it. The next command push the branch to the remote repository origin and tracks it

git push -u origin your_branch

Your Teammates/colleagues can push to your branch by doing commits and then push explicitly

... work ...
git commit
... work ...
git commit
git push origin HEAD:refs/heads/your_branch 

How can I compare strings in C using a `switch` statement?

My preferred method for doing this is via a hash function (borrowed from here). This allows you to utilize the efficiency of a switch statement even when working with char *'s:

#include "stdio.h"

#define LS 5863588
#define CD 5863276
#define MKDIR 210720772860
#define PWD 193502992

const unsigned long hash(const char *str) {
    unsigned long hash = 5381;  
    int c;

    while ((c = *str++))
        hash = ((hash << 5) + hash) + c;
    return hash;

int main(int argc, char *argv[]) {
    char *p_command = argv[1];
    switch(hash(p_command)) {
    case LS:
        printf("Running ls...\n");
    case CD:
        printf("Running cd...\n");
    case MKDIR:
        printf("Running mkdir...\n");
    case PWD:
        printf("Running pwd...\n");
        printf("[ERROR] '%s' is not a valid command.\n", p_command);

Of course, this approach requires that the hash values for all possible accepted char *'s are calculated in advance. I don't think this is too much of an issue; however, since the switch statement operates on fixed values regardless. A simple program can be made to pass char *'s through the hash function and output their results. These results can then be defined via macros as I have done above.

Is there a way to represent a directory tree in a Github

I wrote a small script that does the trick:


#File: tree-md

tree=$(tree -tf --noreport -I '*~' --charset ascii $1 |
       sed -e 's/| \+/  /g' -e 's/[|`]-\+/ */g' -e 's:\(* \)\(\(.*/\)\([^/]\+\)\):\1[\4](\2):g')

printf "# Project tree\n\n${tree}"


Original tree command:

$ tree
+-- dir1
¦   +-- file11.ext
¦   +-- file12.ext
+-- dir2
¦   +-- file21.ext
¦   +-- file22.ext
¦   +-- file23.ext
+-- dir3
+-- file_in_root.ext

3 directories, 7 files

Markdown tree command:

$ ./tree-md .
# Project tree

 * [tree-md](./tree-md)
 * [dir2](./dir2)
   * [file21.ext](./dir2/file21.ext)
   * [file22.ext](./dir2/file22.ext)
   * [file23.ext](./dir2/file23.ext)
 * [dir1](./dir1)
   * [file11.ext](./dir1/file11.ext)
   * [file12.ext](./dir1/file12.ext)
 * [file_in_root.ext](./file_in_root.ext)
 * [](./
 * [dir3](./dir3)

Rendered result:

(Links are not visible in Stackoverflow...)

Project tree
  • tree-md
  • dir2
    • file21.ext
    • file22.ext
    • file23.ext
  • dir1
    • file11.ext
    • file12.ext
  • file_in_root.ext
  • dir3

How to know if two arrays have the same values

A function to Compare two Arrays, to check if both has same elements. Even if they are out of order...

It's good for simple arrays. [String,Number,Boolean,null,NaN].

I don't use .sort(), it modifies the original array. Some say's its bad...

Caution. This function is limited it can't compare Objects"[],{}" or functions within these Arrays, arrays it's self are Objects.

   let arraysHasSameElements = (arr1, arr2) => {
        let count =
            // returns counting of occurrences.
            (arr, val) => arr.reduce((count, curr) => (curr === val ? 1 : 0) + count, 0);

        /* this will return true if lengths of the arrays is equal.
           then compare them.*/
        return arr1.length === arr2.length

            // compare arr1 against arr2.
            && arr1.reduce((checks, val) =>

                /*  creating array of checking if a value has equal amount of occurrences
                    in both arrays, then adds true 'check'. */
                checks.concat(count(arr1, val) === count(arr2, val)), [])

                // checking if each check is equal to true, then .every() returns true.
                .every(check => check);

    let arr1 = ['',-99,true,NaN,21,null,false,'help',-99,'help',NaN], 
        arr2 = [null,-99,'',NaN,NaN,false,true,-99,'help',21,'help'];
    arraysHasSameElements(arr1, arr2); //true

    let arr3 = [false,false,false,false,false,false], 
        arr4 = [false,false,false,false,false,false]
    arraysHasSameElements(arr3, arr4); //true

    // here we have uncommented version.
    let arraysHasSameElements = (arr1, arr2) => {
        let count = (arr, val) => arr.reduce((count, curr) => (curr === val ? 1:0) + count, 0);
        return arr1.length === arr2.length && arr1.reduce((checks, val) =>
            checks.concat(count(arr1, val) === count(arr2, val)), []).every(check => check);

How to capitalize first letter of each word, like a 2-word city?

function convertCase(str) {
  var lower = String(str).toLowerCase();
  return lower.replace(/(^| )(\w)/g, function(x) {
    return x.toUpperCase();

Go to "next" iteration in JavaScript forEach loop

just return true inside your if statement

var myArr = [1,2,3,4];

  if (elem === 3) {

      return true;

    // Go to "next" iteration. Or "continue" to next iteration...


What is the difference between i = i + 1 and i += 1 in a 'for' loop?

The short form(a += 1) has the option to modify a in-place , instead of creating a new object representing the sum and rebinding it back to the same name(a = a + 1).So,The short form(a += 1) is much efficient as it doesn't necessarily need to make a copy of a unlike a = a + 1.

Also even if they are outputting the same result, notice they are different because they are separate operators: + and +=

How to serialize an object into a string

XStream provides a simple utility for serializing/deserializing to/from XML, and it's very quick. Storing XML CLOBs rather than binary BLOBS is going to be less fragile, not to mention more readable.

Get the current cell in Excel VB

The keyword "Selection" is already a vba Range object so you can use it directly, and you don't have to select cells to copy, for example you can be on Sheet1 and issue these commands:


If it is a multiple selection you should use the Area object in a for loop:

Dim a as Range
For Each a in ActiveSheet.Selection.Areas



How to completely hide the navigation bar in iPhone / HTML5

The problem with all of the answers given so far is that on the something borrowed site, the Mac bar remains totally hidden when scrolling up, and the provided answers don't accomplish that.

If you just use scrollTo and then the user later scrolls up, the nav bar is revealed again, so it seems you have to put the whole site inside of a div and force scrolling to happen inside of that div rather than on the body which keeps the nav bar hidden during scrolling in any direction.

You can, however, still reveal the nav bar by touching near the top of the screen on apple devices.

Node.js Best Practice Exception Handling

I would just like to add that Step.js library helps you handle exceptions by always passing it to the next step function. Therefore you can have as a last step a function that check for any errors in any of the previous steps. This approach can greatly simplify your error handling.

Below is a quote from the github page:

any exceptions thrown are caught and passed as the first argument to the next function. As long as you don't nest callback functions inline your main functions this prevents there from ever being any uncaught exceptions. This is very important for long running node.JS servers since a single uncaught exception can bring the whole server down.

Furthermore, you can use Step to control execution of scripts to have a clean up section as the last step. For example if you want to write a build script in Node and report how long it took to write, the last step can do that (rather than trying to dig out the last callback).

Update index after sorting data-frame

df.sort() is deprecated, use df.sort_values(...):

Then follow joris' answer by doing df.reset_index(drop=True)

How to add screenshot to READMEs in github repository?

The markdown syntax for displaying images is indeed:


BUT: How to provide the url ?

  • You probably do not want to clutter your repo with screenshots, they have nothing to do with code
  • you might not want either to deal with the hassle of making your image available on the web... (upload it to a server... ).

So... you can use this awesome trick to make github host your image file. TDLR:

  1. create an issue on the issue list of your repo
  2. drag and drop your screenshot on this issue
  3. copy the markdown code that github has just created for you to display your image
  4. paste it on your readme (or wherever you want)

How to remove \n from a list element?

It sounds like you want something like the Perl chomp() function.

That's trivial to do in Python:

def chomp(s):
    return s[:-1] if s.endswith('\n') else s

... assuming you're using Python 2.6 or later. Otherwise just use the slightly more verbose:

def chomp(s):
    if s.endwith('\n'):
        return s[:-1]
        return s

If you want to remove all new lines from the end of a string (in the odd case where one might have multiple trailing newlines for some reason):

def chomps(s):
    return s.rstrip('\n')

Obviously you should never see such a string returned by any normal Python file object's readline() nor readlines() methods.

I've seen people blindly remove the last characters (using s[:-1] slicing) from the results of file readline() and similar functions. This is a bad idea because it can lead to an error on the last line of the file (in the case where a file ends with anything other than a newline).

At first you might be lulled into a false sense of security when blindly stripping final characters off lines you've read. If you use a normal text editor to create your test suite files you'll have a newline silently added to the end of the last line by most of them. To create a valid test file use code something like:

f = open('sometest.txt', 'w')
f.write('some text')

... and then if you re-open that file and use the readline() or readlines() file methods on it you'll find that the text is read without the trailing newline.

This failure to account for text files ending in non-newline characters has plagued many UNIX utilities and scripting languages for many years. It's a stupid corner base bug that creeps into code just often enough to be a pest but not often enough for people to learn from it. We could argue that "text" files without the ultimate newline are "corrupt" or non-standard; and that may be valid for some programming specifications.

However, it's all too easy to ignore corner cases in our coding and have that ignorance bite people who are depending on your code later. As my wife says: when it comes to programming ... practice safe hex!

How do I get Bin Path?


eg. value:


Can an int be null in Java?

In Java, int is a primitive type and it is not considered an object. Only objects can have a null value. So the answer to your question is no, it can't be null. But it's not that simple, because there are objects that represent most primitive types.

The class Integer represents an int value, but it can hold a null value. Depending on your check method, you could be returning an int or an Integer.

This behavior is different from some more purely object oriented languages like Ruby, where even "primitive" things like ints are considered objects.

Non-static variable cannot be referenced from a static context

You must understand the difference between a class and an instance of that class. If you see a car on the street, you know immediately that it's a car even if you can't see which model or type. This is because you compare what you see with the class "car". The class contains which is similar to all cars. Think of it as a template or an idea.

At the same time, the car you see is an instance of the class "car" since it has all the properties which you expect: There is someone driving it, it has an engine, wheels.

So the class says "all cars have a color" and the instance says "this specific car is red".

In the OO world, you define the class and inside the class, you define a field of type Color. When the class is instantiated (when you create a specific instance), memory is reserved for the color and you can give this specific instance a color. Since these attributes are specific, they are non-static.

Static fields and methods are shared with all instances. They are for values which are specific to the class and not a specific instance. For methods, this usually are global helper methods (like Integer.parseInt()). For fields, it's usually constants (like car types, i.e. something where you have a limited set which doesn't change often).

To solve your problem, you need to instantiate an instance (create an object) of your class so the runtime can reserve memory for the instance (otherwise, different instances would overwrite each other which you don't want).

In your case, try this code as a starting block:

public static void main (String[] args)
        MyProgram7 obj = new MyProgram7 (); (args);
    catch (Exception e)
        e.printStackTrace ();

// instance variables here

public void run (String[] args) throws Exception
    // put your code here

The new main() method creates an instance of the class it contains (sounds strange but since main() is created with the class instead of with the instance, it can do this) and then calls an instance method (run()).

How to display an alert box from C# in ASP.NET?

If you don't have a Page.Redirect(), use this

Response.Write("<script>alert('Inserted successfully!')</script>"); //works great

But if you do have Page.Redirect(), use this

Response.Write("<script>alert('Inserted..');window.location = 'newpage.aspx';</script>"); //works great

works for me.

Hope this helps.

How to return 2 values from a Java method?

You don't need to create your own class to return two different values. Just use a HashMap like this:

private HashMap<Toy, GameLevel> getToyAndLevelOfSpatial(Spatial spatial)
    Toy toyWithSpatial = firstValue;
    GameLevel levelToyFound = secondValue;

    HashMap<Toy,GameLevel> hm=new HashMap<>();
    hm.put(toyWithSpatial, levelToyFound);
    return hm;

private void findStuff()
    HashMap<Toy, GameLevel> hm = getToyAndLevelOfSpatial(spatial);
    Toy firstValue = hm.keySet().iterator().next();
    GameLevel secondValue = hm.get(firstValue);

You even have the benefit of type safety.

How do I grab an INI value within a shell script?

You may use crudini tool to get ini values, e.g.:

DATABASE_VERSION=$(crudini --get parameters.ini '' database_version)

How to get `DOM Element` in Angular 2?

Angular 2.0.0 Final:

I have found that using a ViewChild setter is most reliable way to set the initial form control focus:

set myInput(_input: ElementRef | undefined) {
    if (_input !== undefined) {
        setTimeout(() => {
            this._renderer.invokeElementMethod(_input.nativeElement, "focus");
        }, 0);

The setter is first called with an undefined value followed by a call with an initialized ElementRef.

Working example and full source here:

Using TypeScript 2.0.3 Final/RTM, Angular 2.0.0 Final/RTM, and Chrome 53.0.2785.116 m (64-bit).

UPDATE for Angular 4+

Renderer has been deprecated in favor of Renderer2, but Renderer2 does not have the invokeElementMethod. You will need to access the DOM directly to set the focus as in input.nativeElement.focus().

I'm still finding that the ViewChild setter approach works best. When using AfterViewInit I sometimes get read property 'nativeElement' of undefined error.

set myInput(_input: ElementRef | undefined) {
    if (_input !== undefined) {
        setTimeout(() => { //This setTimeout call may not be necessary anymore.
        }, 0);

How can I check if mysql is installed on ubuntu?

Multiple ways of searching for the program.

Type mysql in your terminal, see the result.

Search the /usr/bin, /bin directories for the binary.

Type apt-cache show mysql to see if it is installed

locate mysql

Object passed as parameter to another class, by value or reference?

"Objects" are NEVER passed in C# -- "objects" are not values in the language. The only types in the language are primitive types, struct types, etc. and reference types. No "object types".

The types Object, MyClass, etc. are reference types. Their values are "references" -- pointers to objects. Objects can only be manipulated through references -- when you do new on them, you get a reference, the . operator operates on a reference; etc. There is no way to get a variable whose value "is" an object, because there are no object types.

All types, including reference types, can be passed by value or by reference. A parameter is passed by reference if it has a keyword like ref or out. The SetObject method's obj parameter (which is of a reference type) does not have such a keyword, so it is passed by value -- the reference is passed by value.

Trying to make bootstrap modal wider

Always have handy the un-minified CSS for bootstrap so you can see what styles they have on their components, then create a CSS file AFTER it, if you don't use LESS and over-write their mixins or whatever

This is the default modal css for 768px and up:

@media (min-width: 768px) {
  .modal-dialog {
    width: 600px;
    margin: 30px auto;

They have a class modal-lg for larger widths

@media (min-width: 992px) {
  .modal-lg {
    width: 900px;

If you need something twice the 600px size, and something fluid, do something like this in your CSS after the Bootstrap css and assign that class to the modal-dialog.

@media (min-width: 768px) {
  .modal-xl {
    width: 90%;


<div class="modal-dialog modal-xl">


Is there a way that I can check if a data attribute exists?

if ($("#dataTable").data('timer')) {

NOTE this only returns true if the data attribute is not empty string or a "falsey" value e.g. 0 or false.

If you want to check for the existence of the data attribute, even if empty, do this:

if (typeof $("#dataTable").data('timer') !== 'undefined') {

How can I trigger a JavaScript event click

Please call trigger function any where and button will click.

<a href="#" id="myBtn" title="" >Button click </a>

function trigger(){

segmentation fault : 11

This declaration:

double F[1000][1000000];

would occupy 8 * 1000 * 1000000 bytes on a typical x86 system. This is about 7.45 GB. Chances are your system is running out of memory when trying to execute your code, which results in a segmentation fault.

What does the term "Tuple" Mean in Relational Databases?

Most of the answers here are on the right track. However, a row is not a tuple. Tuples* are unordered sets of known values with names. Thus, the following tuples are the same thing (I'm using an imaginary tuple syntax since a relational tuple is largely a theoretical construct):

(x=1, y=2, z=3)
(z=3, y=2, x=1)
(y=2, z=3, x=1)

...assuming of course that x, y, and z are all integers. Also note that there is no such thing as a "duplicate" tuple. Thus, not only are the above equal, they're the same thing. Lastly, tuples can only contain known values (thus, no nulls).

A row** is an ordered set of known or unknown values with names (although they may be omitted). Therefore, the following comparisons return false in SQL:

(1, 2, 3) = (3, 2, 1)
(3, 1, 2) = (2, 1, 3)

Note that there are ways to "fake it" though. For example, consider this INSERT statement:

INSERT INTO point VALUES (1, 2, 3)

Assuming that x is first, y is second, and z is third, this query may be rewritten like this:

INSERT INTO point (x, y, z) VALUES (1, 2, 3)

Or this:

INSERT INTO point (y, z, x) VALUES (2, 3, 1)

...but all we're really doing is changing the ordering rather than removing it.

And also note that there may be unknown values as well. Thus, you may have rows with unknown values:

(1, 2, NULL) = (1, 2, NULL)

...but note that this comparison will always yield UNKNOWN. After all, how can you know whether two unknown values are equal?

And lastly, rows may be duplicated. In other words, (1, 2) and (1, 2) may compare to be equal, but that doesn't necessarily mean that they're the same thing.

If this is a subject that interests you, I'd highly recommend reading SQL and Relational Theory: How to Write Accurate SQL Code by CJ Date.

* Note that I'm talking about tuples as they exist in the relational model, which is a bit different from mathematics in general.

**And just in case you're wondering, just about everything in SQL is a row or table. Therefore, (1, 2) is a row, while VALUES (1, 2) is a table (with one row).

UPDATE: I've expanded a little bit on this answer in a blog post here.

The type initializer for 'Oracle.DataAccess.Client.OracleConnection' threw an exception

This is an old, but still relevant question, and while the answers here are helpful no one answer fully addressed both of the OP's questions.

1. Do I have to install ODP.NET and Oracle client on the computer that I want to run my application?

YES - if you are using ODP.NET, Unmanaged. This is the version that you typically install when you choose "Oracle Data Provider for .NET" in the Oracle Client installer (for example). You Download this from Oracle (just google it: Oracle URLs change often).

But If you are using ODP.NET, Managed (and you probably want to use this one this instead) then No, you only need to install (or deploy) ODP.NET, Managed with the app, not the full Oracle Client. See below for details.

2. If yes, is there other way that I don't have to install them but still can run my application?

Yes, there is at least one way. And it is the Managed port of ODP.NET.

Unfortunately the usual workarounds, including ODBC, Microsoft's Oracle Provider for .NET (yes, that old, deprecated one), and the ODP.NET, Unmanaged DLL all require the Oracle client to be installed. It wasn't until our friends at Oracle gave us a nice little (~5MB) DLL that is also Managed. This means no more having to depoy 32-bit and 64-bit versions to go with 32-bit and 64-bit Oracle clients! And no more issues with assembly binding where you build against (or whatever) but your customers install a range of clients from 9i all the way to 12c, including the 'g' ones in the middle) because you can just ship it with your app, and manage it via nuget.

But if you use ODP.NET, Managed which is available as a nuget package, then you do not need to install the Oracle Client. You only need the ODP.NET, Managed DLL. And if you were previously using the ODP.NET, Unmanaged DLL, it is very easy to switch: simply change all your references to the Managed ODP.NET (.csproj files in csharp, etc.), and then change any using statements, for example: using Oracle.DataAccess.Client becomes using Oracle.ManagedDataAccess.Client and that's it! (Unless you were supposedly using some of the more advanced DB management features in the full client that are exposed in the ODP.NET, Unmanaged, which I have not done myself, so good luck with that..). And also nuke all of those annoying assemblyBindingRedirect nodes from your app.config/web.config files and never sweat that junk again!



That error typically means ODP.NET was found OK, but Oracle client was not found or not installed. This could also occur when the architecture doesn't match (32-bit Oracle client is installed, but trying to use 64-bit Unmanaged ODP.NET, or vice versa). This can also happen due to permissions issues and path issues and other problems with the app domain (your web app or your EXE or whatever) not being able to find the Oracle DLLs to actually communicate with Oracle over the network (the ODP.NET Unmanaged DLLs are basically just wrappers for this that hook into ADO and stuff).

Common solutions I have found to this problem:

App is 64-bit?

  • Install 64-bit Oracle Client (32-bit one wont work)

App is 32-bit?

  • Install 32-bit Oracle Client (64-bit one wont work)

Oracle Client is already installed for the correct architecture?

  • Verify your environment PATH and ORACLE_HOME variables, make sure Oracle can be found (newer versions may use Registry instead)
  • Verify the ORACLE_HOME and settings in the Registry (And remember: Registry is either 32-bit or 64-bit, so make sure you check the one that matches your app!)
  • Verify permissions on the ORACLE_HOME folder. If you don't know where this is, check the Registry. I have seen cases where ASP.NET app worker process was using Network Service user and for some reason installing 32-bit and 64-bit clients side by side resulted in the permissions being removed from the first client for the Authorized Users group.. fixing perms on the home folder fixed this.
  • As always, it is handy to Use SysInternals Process Monitor to find out what file is missing or can't be read.

Django development IDE

I made a blog post about NetBeans' new and upcoming support for Django. When paired with its already fantastic Python, JavaScript, HTML and CSS support, it's a strong candidate in my mind!

How to compare strings in an "if" statement?

You can't compare array of characters using == operator. You have to use string compare functions. Take a look at Strings (c-faq).

The standard library's strcmp function compares two strings, and returns 0 if they are identical, or a negative number if the first string is alphabetically "less than" the second string, or a positive number if the first string is "greater."

A Windows equivalent of the Unix tail command

The tail command and many others are available in the Windows Resource Kit Tools package.

HTML Display Current date

var currentDate  = new Date(),
    currentDay   = currentDate.getDate() < 10 
                 ? '0' + currentDate.getDate() 
                 : currentDate.getDate(),
    currentMonth = currentDate.getMonth() < 9 
                 ? '0' + (currentDate.getMonth() + 1) 
                 : (currentDate.getMonth() + 1);

document.getElementById("date").innerHTML = currentDay + '/' + currentMonth + '/' +  currentDate.getFullYear();

You can read more about Date object

Add resources, config files to your jar using gradle

Be aware that the path under src/main/resources must match the package path of your .class files wishing to access the resource. See my answer here.

Working with huge files in VIM

emacs works very well with files into the 100's of megabytes, I've used it on log files without too much trouble.

But generally when I have some kind of analysis task, I find writing a perl script a better choice.

How to understand nil vs. empty vs. blank in Ruby

.nil? can be used on any object and is true if the object is nil.

.empty? can be used on strings, arrays and hashes and returns true if:

  • String length == 0
  • Array length == 0
  • Hash length == 0

Running .empty? on something that is nil will throw a NoMethodError.

That is where .blank? comes in. It is implemented by Rails and will operate on any object as well as work like .empty? on strings, arrays and hashes.

nil.blank? == true
false.blank? == true
[].blank? == true
{}.blank? == true
"".blank? == true
5.blank? == false
0.blank? == false

.blank? also evaluates true on strings which are non-empty but contain only whitespace:

"  ".blank? == true
"  ".empty? == false

Rails also provides .present?, which returns the negation of .blank?.

Array gotcha: blank? will return false even if all elements of an array are blank. To determine blankness in this case, use all? with blank?, for example:

[ nil, '' ].blank? == false
[ nil, '' ].all? &:blank? == true 

PHP absolute path to root

Create a constant with absolute path to the root by using define in ShowInfo.php:

define('ROOTPATH', __DIR__);

Or PHP <= 5.3

define('ROOTPATH', dirname(__FILE__));

Now use it:

if (file_exists(ROOTPATH.'/Texts/MyInfo.txt')) {
  // ...

Or use the DOCUMENT_ROOT defined in $_SERVER:

if (file_exists($_SERVER['DOCUMENT_ROOT'].'/Texts/MyInfo.txt')) {
  // ...

How to subtract n days from current date in java?

I found this perfect solution and may useful, You can directly get in format as you want:

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -90); // I just want date before 90 days. you can give that you want.

SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd"); // you can specify your format here...
Log.d("DATE","Date before 90 Days: " + s.format(new Date(cal.getTimeInMillis())));


Get product id and product type in magento?

you can get all product information from following code


    $product_data["special price"]=$_product->getFinalPrice();
    $product_data["color"]=$_product->getAttributeText('color'); //get cusom attribute value

    $storeId = Mage::app()->getStore()->getId();
    $summaryData = Mage::getModel('review/review_summary')->setStoreId($storeId)  ->load($_product->getId());


    if($_product->isSalable() ==1)

    echo "<pre>";
    //echo "</pre>";

Align the form to the center in Bootstrap 4

All above answers perfectly gives the solution to center the form using Bootstrap 4. However, if someone wants to use out of the box Bootstrap 4 css classes without help of any additional styles and also not wanting to use flex, we can do like this.

A sample form

enter image description here


<div class="container-fluid h-100 bg-light text-dark">
  <div class="row justify-content-center align-items-center">
  <div class="row justify-content-center align-items-center h-100">
    <div class="col col-sm-6 col-md-6 col-lg-4 col-xl-3">
      <form action="">
        <div class="form-group">
          <select class="form-control">
                    <option>Option 1</option>
                    <option>Option 2</option>
        <div class="form-group">
          <input type="text" class="form-control" />
        <div class="form-group text-center">
          <div class="form-check-inline">
            <label class="form-check-label">
    <input type="radio" class="form-check-input" name="optradio">Option 1
          <div class="form-check-inline">
            <label class="form-check-label">
    <input type="radio" class="form-check-input" name="optradio">Option 2
          <div class="form-check-inline">
            <label class="form-check-label">
    <input type="radio" class="form-check-input" name="optradio" disabled>Option 3
        <div class="form-group">
          <div class="container">
            <div class="row">
              <div class="col"><button class="col-6 btn btn-secondary btn-sm float-left">Reset</button></div>
              <div class="col"><button class="col-6 btn btn-primary btn-sm float-right">Submit</button></div>


Link to CodePen

I hope this helps someone. Thank you.

How to create a pulse effect using -webkit-animation - outward rings

You have a lot of unnecessary keyframes. Don't think of keyframes as individual frames, think of them as "steps" in your animation and the computer fills in the frames between the keyframes.

Here is a solution that cleans up a lot of code and makes the animation start from the center:

.gps_ring {
    border: 3px solid #999;
    -webkit-border-radius: 30px;
    height: 18px;
    width: 18px;
    position: absolute;
    -webkit-animation: pulsate 1s ease-out;
    -webkit-animation-iteration-count: infinite; 
    opacity: 0.0
@-webkit-keyframes pulsate {
    0% {-webkit-transform: scale(0.1, 0.1); opacity: 0.0;}
    50% {opacity: 1.0;}
    100% {-webkit-transform: scale(1.2, 1.2); opacity: 0.0;}

You can see it in action here:

How to change the color of winform DataGridview header?

If you want to change a color to single column try this:

 dataGridView1.EnableHeadersVisualStyles = false;
 dataGridView1.Columns[0].HeaderCell.Style.BackColor = Color.Magenta;
 dataGridView1.Columns[1].HeaderCell.Style.BackColor = Color.Yellow;

Decompile an APK, modify it and then recompile it

Thanks to Chris Jester-Young I managed to make it work!

I think the way I managed to do it will work only on really simple projects:

  • With Dex2jar I obtained the Jar.
  • With jd-gui I convert my Jar back to Java files.
  • With apktool i got the android manifest and the resources files.

  • In Eclipse I create a new project with the same settings as the old one (checking all the information in the manifest file)

  • When the project is created I'm replacing all the resources and the manifest with the ones I obtained with apktool
  • I paste the java files I extracted from the Jar in the src folder (respecting the packages)
  • I modify those files with what I need
  • Everything is compiling!

/!\ be sure you removed the old apk from the device an error will be thrown stating that the apk signature is not the same as the old one!

Java: convert List<String> to a String

You can use the apache commons library which has a StringUtils class and a join method.

Check this link:

Note that the link above may become obsolete over time, in which case you can just search the web for "apache commons StringUtils", which should allow you to find the latest reference.

(referenced from this thread) Java equivalents of C# String.Format() and String.Join()

What are the differences among grep, awk & sed?

I just want to mention a thing, there are many tools can do text processing, e.g. sort, cut, split, join, paste, comm, uniq, column, rev, tac, tr, nl, pr, head, tail.....

they are very handy but you have to learn their options etc.

A lazy way (not the best way) to learn text processing might be: only learn grep , sed and awk. with this three tools, you can solve almost 99% of text processing problems and don't need to memorize above different cmds and options. :)

AND, if you 've learned and used the three, you knew the difference. Actually, the difference here means which tool is good at solving what kind of problem.

a more lazy way might be learning a script language (python, perl or ruby) and do every text processing with it.

How to run a javascript function during a mouseover on a div

Here's a jQuery solution.

<script type="text/javascript" src="/path/to/your/copy/of/jquery-1.3.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
    $("#sub1").mouseover(function() {

Using this markup:

<div id="sub1">some text</div>
<div id="welcome" style="display:none;">Welcome message</div>

You didn't really specify if (or when) you wanted to hide the welcome message, but this would toggle hiding or showing each time you moused over the text.

raw vs. html_safe vs. h to unescape html

  1. html_safe :

    Marks a string as trusted safe. It will be inserted into HTML with no additional escaping performed.

    #=> "<a>Hello</a>"
    #=> NoMethodError: undefined method `html_safe' for nil:NilClass
  2. raw :

    raw is just a wrapper around html_safe. Use raw if there are chances that the string will be nil.

    #=> "<a>Hello</a>"
    #=> ""
  3. h alias for html_escape :

    A utility method for escaping HTML tag characters. Use this method to escape any unsafe content.

    In Rails 3 and above it is used by default so you don't need to use this method explicitly

R: numeric 'envir' arg not of length one in predict()

There are several problems here:

  1. The newdata argument of predict() needs a predictor variable. You should thus pass it values for Coupon, instead of Total, which is the response variable in your model.

  2. The predictor variable needs to be passed in as a named column in a data frame, so that predict() knows what the numbers its been handed represent. (The need for this becomes clear when you consider more complicated models, having more than one predictor variable).

  3. For this to work, your original call should pass df in through the data argument, rather than using it directly in your formula. (This way, the name of the column in newdata will be able to match the name on the RHS of the formula).

With those changes incorporated, this will work:

model <- lm(Total ~ Coupon, data=df)
new <- data.frame(Coupon = df$Coupon)
predict(model, newdata = new, interval="confidence")

How can I get last characters of a string

One way would be using slice, like follow:

var id="ctl03_Tabs1";
var temp=id.slice(-5);

so the value of temp would be "Tabs1".

IN Clause with NULL or IS NULL

FROM tbl_name
WHERE coalesce(id_field,'unik_null_value') 
IN ('value1', 'value2', 'value3', 'unik_null_value')

So that you eliminate the null from the check. Given a null value in id_field, the coalesce function would instead of null return 'unik_null_value', and by adding 'unik_null_value to the IN-list, the query would return posts where id_field is value1-3 or null.

Calculate row means on subset of columns

Calculate row means on a subset of columns:

Create a new data.frame which specifies the first column from DF as an column called ID and calculates the mean of all the other fields on that row, and puts that into column entitled 'Means':

data.frame(ID=DF[,1], Means=rowMeans(DF[,-1]))
  ID    Means
1  A 3.666667
2  B 4.333333
3  C 3.333333
4  D 4.666667
5  E 4.333333

Getting GET "?" variable in laravel

I haven't tested on other Laravel versions but on 5.3-5.8 you reference the query parameter as if it were a member of the Request class.

1. Url

2. In a route callback or controller action using magic method Request::__get()

Route::get('/path', function(Request $request){

//or in your controller
public function foo(Request $request){

//NOTE: If you are wondering where the request instance is coming from, Laravel automatically injects the request instance from the IOC container

3. Default values

We can also pass in a default value which is returned if a parameter doesn't exist. It's much cleaner than a ternary expression that you'd normally use with the request globals

   //wrong way to do it in Laravel
   $page = isset($_POST['page']) ? $_POST['page'] : 1; 

   //do this instead
   $request->get('page', 1);

   //returns page 1 if there is no page
   //NOTE: This behaves like $_REQUEST array. It looks in both the
   //request body and the query string
   $request->input('page', 1);

4. Using request function

$page = request('page', 1);
//returns page 1 if there is no page parameter in the query  string
//it is the equivalent of
$page = 1; 
   $page = $_GET['page'];

The default parameter is optional therefore one can omit it

5. Using Request::query()

While the input method retrieves values from entire request payload (including the query string), the query method will only retrieve values from the query string

//this is the equivalent of retrieving the parameter
//from the $_GET global array
$page = $request->query('page');

//with a default
$page = $request->query('page', 1);

6. Using the Request facade

$page = Request::get('page');

//with a default value
$page = Request::get('page', 1);

You can read more in the official documentation

Update built-in vim on Mac OS X

If I understand things correctly, you want to install over your existing Vim, for better or worse :-) This is a bad idea and it is not the "clean" way to do it. Why? Well, OS X expects that nothing will ever change in /usr/bin unbeknownst to it, so any time you overwrite stuff in there you risk breaking some intricate interdependency. And, Let's say you do break something -- there's no way to "undo" that damage. You will be sad and alone. You may have to reinstall OS X.

Part 1: A better idea

The "clean" way is to install in a separate place, and make the new binary higher priority in the $PATH. Here is how I recommend doing that:

$ # Create the directories you need
$ sudo mkdir -p /opt/local/bin
$ # Download, compile, and install the latest Vim
$ cd ~
$ hg clone or git clone
$ cd vim
$ ./configure --prefix=/opt/local
$ make
$ sudo make install
$ # Add the binary to your path, ahead of /usr/bin
$ echo 'PATH=/opt/local/bin:$PATH' >> ~/.bash_profile
$ # Reload bash_profile so the changes take effect in this window
$ source ~/.bash_profile

Voila! Now when we use vim we will be using the new one. But, to get back to our old configuration in the event of huge f*ckups, we can just delete the /opt directory.

$ which vim
$ vim --version | head -n 2
VIM - Vi IMproved 7.3 (2010 Aug 15, compiled Aug 27 2011 20:55:46)
MacOS X (unix) version

See how clean this is.

I recommend not to install in /usr/local/bin when you want to override binaries in /usr/bin, because by default OS X puts /usr/bin higher priority in $PATH than /usr/local/bin, and screwing with that opens its own can of worms.... So, that's what you SHOULD do.

Part 2: The "correct" answer (but a bad idea)

Assuming you're set on doing that, you are definitely on track. To install on top of your current installation, you need to set the "prefix" directory. That's done like this:

hg clone or git clone
cd vim
./configure --prefix=/usr
sudo make install

You can pass "configure" a few other options too, if you want. Do "./configure --help" to see them. I hope you've got a backup before you do it, though, in case something goes wrong....

Import Python Script Into Another?

Hope this work

def break_words(stuff):
    """This function will break up words for us."""
    words = stuff.split(' ')
    return words

def sort_words(words):
    """Sorts the words."""
    return sorted(words)

def print_first_word(words):
    """Prints the first word after popping it off."""
    word = words.pop(0)
    print (word)

def print_last_word(words):
    """Prints the last word after popping it off."""
    word = words.pop(-1)

def sort_sentence(sentence):
    """Takes in a full sentence and returns the sorted words."""
    words = break_words(sentence)
    return sort_words(words)

def print_first_and_last(sentence):
    """Prints the first and last words of the sentence."""
    words = break_words(sentence)

def print_first_and_last_sorted(sentence):
    """Sorts the words then prints the first and last one."""
    words = sort_sentence(sentence)

print ("Let's practice everything.")
print ('You\'d need to know \'bout escapes with \\ that do \n newlines and \t tabs.')

poem = """
\tThe lovely world
with logic so firmly planted
cannot discern \n the needs of love
nor comprehend passion from intuition
and requires an explantion
\n\t\twhere there is none.

print ("--------------")
print (poem)
print ("--------------")

five = 10 - 2 + 3 - 5
print ("This should be five: %s" % five)

def secret_formula(start_point):
    jelly_beans = start_point * 500
    jars = jelly_beans / 1000
    crates = jars / 100
    return jelly_beans, jars, crates

start_point = 10000
jelly_beans, jars, crates = secret_formula(start_point)

print ("With a starting point of: %d" % start_point)
print ("We'd have %d jeans, %d jars, and %d crates." % (jelly_beans, jars, crates))

start_point = start_point / 10

print ("We can also do that this way:")
print ("We'd have %d beans, %d jars, and %d crabapples." % secret_formula(start_point))

sentence = "All god\tthings come to those who weight."

words =  break_words(sentence)
sorted_words =  sort_words(words)

sorted_words =  sort_sentence(sentence)
print (sorted_words)


Using an Alias in a WHERE clause

 SELECT A.identifier
 , TO_NUMBER(DECODE( A.month_no
         , 1, 200803 
         , 2, 200804 
         , 3, 200805 
         , 4, 200806 
         , 5, 200807 
         , 6, 200808 
         , 7, 200809 
         , 8, 200810 
         , 9, 200811 
         , 10, 200812 
         , 11, 200701 
         , 12, 200702
         , NULL)) as MONTH_NO
 , TO_NUMBER(TO_CHAR(B.last_update_date, 'YYYYMM')) as UPD_DATE
FROM table_a A, table_b B
WHERE .identifier = B.identifier

Python - How to sort a list of lists by the fourth element in each list?

Use sorted() with a key as follows -

>>> unsorted_list = [['a','b','c','5','d'],['e','f','g','3','h'],['i','j','k','4','m']]
>>> sorted(unsorted_list, key = lambda x: int(x[3]))
[['e', 'f', 'g', '3', 'h'], ['i', 'j', 'k', '4', 'm'], ['a', 'b', 'c', '5', 'd']]

The lambda returns the fourth element of each of the inner lists and the sorted function uses that to sort those list. This assumes that int(elem) will not fail for the list.

Or use itemgetter (As Ashwini's comment pointed out, this method would not work if you have string representations of the numbers, since they are bound to fail somewhere for 2+ digit numbers)

>>> from operator import itemgetter
>>> sorted(unsorted_list, key = itemgetter(3))
[['e', 'f', 'g', '3', 'h'], ['i', 'j', 'k', '4', 'm'], ['a', 'b', 'c', '5', 'd']]

What is the --save option for npm install?

npm install package_x --save

The given package (package_x) will be saved in package.json inside dependencies. if you add

npm install <<package_x>> --save-dev

then it will be saved inside devDependencies.

Deserializing JSON Object Array with

Using the accepted answer you have to access each record by using Customers[i].customer, and you need an extra CustomerJson class, which is a little annoying. If you don't want to do that, you can use the following:

public class CustomerList
    public List<Customer> customer { get; set; }

Note that I'm using a List<>, not an Array. Now create the following class:

class MyListConverter : JsonConverter
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        var token = JToken.Load(reader);
        var list = Activator.CreateInstance(objectType) as System.Collections.IList;
        var itemType = objectType.GenericTypeArguments[0];
        foreach (var child in token.Values())
            var childToken = child.Children().First();
            var newObject = Activator.CreateInstance(itemType);
            serializer.Populate(childToken.CreateReader(), newObject);
        return list;

    public override bool CanConvert(Type objectType)
        return objectType.IsGenericType && (objectType.GetGenericTypeDefinition() == typeof(List<>));
    public override bool CanWrite => false;
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) => throw new NotImplementedException();

Is it possible to get the index you're sorting over in Underscore.js?

I think it's worth mentioning how the Underscore's _.each() works internally. The _.each(list, iteratee) checks if the passed list is an array object, or an object.

In the case that the list is an array, iteratee arguments will be a list element and index as in the following example:

var a = ['I', 'like', 'pancakes', 'a', 'lot', '.'];
_.each( a, function(v, k) { console.log( k + " " + v); });

0 I
1 like
2 pancakes
3 a
4 lot
5 .

On the other hand, if the list argument is an object the iteratee will take a list element and a key:

var o = {name: 'mike', lastname: 'doe', age: 21};
_.each( o, function(v, k) { console.log( k + " " + v); });

name mike
lastname doe
age 21

For reference this is the _.each() code from Underscore.js 1.8.3

_.each = _.forEach = function(obj, iteratee, context) {
   iteratee = optimizeCb(iteratee, context);
   var i, length;
   if (isArrayLike(obj)) {
      for (i = 0, length = obj.length; i < length; i++) {
         iteratee(obj[i], i, obj);
   } else {
      var keys = _.keys(obj);
      for (i = 0, length = keys.length; i < length; i++) {
         iteratee(obj[keys[i]], keys[i], obj);
   return obj;

Convert HTML to NSAttributedString in iOS

This is a String extension written in Swift to return a HTML string as NSAttributedString.

extension String {
    func htmlAttributedString() -> NSAttributedString? {
        guard let data = self.dataUsingEncoding(NSUTF16StringEncoding, allowLossyConversion: false) else { return nil }
        guard let html = try? NSMutableAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) else { return nil }
        return html

To use,

label.attributedText = "<b>Hello</b> \u{2022} babe".htmlAttributedString()

In the above, I have purposely added a unicode \u2022 to show that it renders unicode correctly.

A trivial: The default encoding that NSAttributedString uses is NSUTF16StringEncoding (not UTF8!).

List all environment variables from the command line

Jon has the right answer, but to elaborate a little more with some syntactic sugar..

SET | more

enables you to see the variables one page at a time, rather than the whole lot, or

SET > output.txt

sends the output to a file output.txt which you can open in Notepad or whatever...

CSS table-cell equal width

Just using max-width: 0 in the display: table-cell element worked for me:

.table {_x000D_
  display: table;_x000D_
  width: 100%;_x000D_
.table-cell {_x000D_
  display: table-cell;_x000D_
  max-width: 0px;_x000D_
  border: 1px solid gray;_x000D_
<div class="table">_x000D_
  <div class="table-cell">short</div>_x000D_
  <div class="table-cell">loooooong</div>_x000D_
  <div class="table-cell">Veeeeeeery loooooong</div>_x000D_

How can I show three columns per row?

Try this one using Grid Layout:

.grid-container {_x000D_
  display: grid;_x000D_
  grid-template-columns: auto auto auto;_x000D_
  padding: 10px;_x000D_
.grid-item {_x000D_
  background-color: rgba(255, 255, 255, 0.8);_x000D_
  border: 1px solid rgba(0, 0, 0, 0.8);_x000D_
  padding: 20px;_x000D_
  font-size: 30px;_x000D_
  text-align: center;_x000D_
<div class="grid-container">_x000D_
  <div class="grid-item">1</div>_x000D_
  <div class="grid-item">2</div>_x000D_
  <div class="grid-item">3</div>  _x000D_
  <div class="grid-item">4</div>_x000D_
  <div class="grid-item">5</div>_x000D_
  <div class="grid-item">6</div>  _x000D_
  <div class="grid-item">7</div>_x000D_
  <div class="grid-item">8</div>_x000D_
  <div class="grid-item">9</div>  _x000D_

How to disable an Android button?

In my case,


is working fine and it is enabling and disabling the button as it should. But once the button state becomes disabled, it never goes back to the enabled state again, although it's clickable. I tried invalidating and refreshing the drawable state, but no luck.


If you or anyone having a similar issue, what works for me is setting the background drawable again. Works on any API Level.


How can I join multiple SQL tables using the IDs?

You have not joined TableD, merely selected the TableD FIELD (dID) from one of the tables.

How do I configure IIS for URL Rewriting an AngularJS application in HTML5 mode?

In my case I kept getting a 403.14 after I had setup the correct rewrite rules. It turns out that I had a directory that was the same name as one of my URL routes. Once I removed the IsDirectory rewrite rule my routes worked correctly. Is there a case where removing the directory negation may cause problems? I can't think of any in my case. The only case I can think of is if you can browse a directory with your app.

<rule name="fixhtml5mode" stopProcessing="true">
  <match url=".*"/>
  <conditions logicalGrouping="MatchAll">
    <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
  <action type="Rewrite" url="/" />

Force hide address bar in Chrome on Android

Check this has everything you need

The Chrome team has recently implemented a feature that tells the browser to launch the page fullscreen when the user has added it to the home screen. It is similar to the iOS Safari model.

<meta name="mobile-web-app-capable" content="yes">

How to use EOF to run through a text file in C?

How you detect EOF depends on what you're using to read the stream:

function                  result on EOF or error                    
--------                  ----------------------
fgets()                   NULL
fscanf()                  number of succesful conversions
                            less than expected
fgetc()                   EOF
fread()                   number of elements read
                            less than expected

Check the result of the input call for the appropriate condition above, then call feof() to determine if the result was due to hitting EOF or some other error.

Using fgets():

 char buffer[BUFFER_SIZE];
 while (fgets(buffer, sizeof buffer, stream) != NULL)
   // process buffer
 if (feof(stream))
   // hit end of file
   // some other error interrupted the read

Using fscanf():

char buffer[BUFFER_SIZE];
while (fscanf(stream, "%s", buffer) == 1) // expect 1 successful conversion
  // process buffer
if (feof(stream)) 
  // hit end of file
  // some other error interrupted the read

Using fgetc():

int c;
while ((c = fgetc(stream)) != EOF)
  // process c
if (feof(stream))
  // hit end of file
  // some other error interrupted the read

Using fread():

char buffer[BUFFER_SIZE];
while (fread(buffer, sizeof buffer, 1, stream) == 1) // expecting 1 
                                                     // element of size
                                                     // BUFFER_SIZE
   // process buffer
if (feof(stream))
  // hit end of file
  // some other error interrupted read

Note that the form is the same for all of them: check the result of the read operation; if it failed, then check for EOF. You'll see a lot of examples like:

  fscanf(stream, "%s", buffer);

This form doesn't work the way people think it does, because feof() won't return true until after you've attempted to read past the end of the file. As a result, the loop executes one time too many, which may or may not cause you some grief.

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

To find the next (still not used) auto-increment, I am using this function for somewhat years now.

public function getNewAI($table)
        $newAI = false;

        $mysqli = new mysqli(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);
        if(mysqli_connect_errno()) {
            echo "Failed to connect to MySQL: " . mysqli_connect_error();

        $sql = "SHOW TABLE STATUS LIKE '".$table."'";

        $result = $mysqli->query($sql);

        if($result) {
            $row = $result->fetch_assoc();

            $newAI = $row['Auto_increment'];

        return $newAI;

min and max value of data type in C

You'll want to use limits.h which provides the following constants (as per the linked reference):

SCHAR_MIN      : minimum value for a signed char
SCHAR_MAX      : maximum value for a signed char
UCHAR_MAX      : maximum value for an unsigned char
CHAR_MIN       : minimum value for a char
CHAR_MAX       : maximum value for a char
SHRT_MIN       : minimum value for a short
SHRT_MAX       : maximum value for a short
USHRT_MAX      : maximum value for an unsigned short
INT_MIN        : minimum value for an int
INT_MAX        : maximum value for an int
UINT_MAX       : maximum value for an unsigned int
LONG_MIN       : minimum value for a long
LONG_MAX       : maximum value for a long
ULONG_MAX      : maximum value for an unsigned long
LLONG_MIN      : minimum value for a long long
LLONG_MAX      : maximum value for a long long
ULLONG_MAX     : maximum value for an unsigned long long
PTRDIFF_MIN    : minimum value of ptrdiff_t
PTRDIFF_MAX    : maximum value of ptrdiff_t
SIZE_MAX       : maximum value of size_t
SIG_ATOMIC_MIN : minimum value of sig_atomic_t
SIG_ATOMIC_MAX : maximum value of sig_atomic_t
WINT_MIN       : minimum value of wint_t
WINT_MAX       : maximum value of wint_t
WCHAR_MIN      : minimum value of wchar_t
WCHAR_MAX      : maximum value of wchar_t
CHAR_BIT       : number of bits in a char
MB_LEN_MAX     : maximum length of a multibyte character in bytes

Where U*_MIN is omitted for obvious reasons (any unsigned type has a minimum value of 0).

Similarly float.h provides limits for float and double types:

FLT_MIN    : smallest normalised positive value of a float
FLT_MAX    : largest positive finite value of a float
DBL_MIN    : smallest normalised positive value of a double
DBL_MAX    : largest positive finite value of a double
LDBL_MIN   : smallest normalised positive value of a long double
LDBL_MAX   : largest positive finite value of a long double
FLT_DIG    : the number of decimal digits guaranteed to be preserved converting from text to float and back to text
DBL_DIG    : the number of decimal digits guaranteed to be preserved converting from text to double and back to text
LDBL_DIG   : the number of decimal digits guaranteed to be preserved converting from text to long double and back to text

Floating point types are symmetrical around zero, so the most negative finite number is the negation of the most positive finite number - eg float ranges from -FLT_MAX to FLT_MAX.

Do note that floating point types can only exactly represent a small, finite number of values within their range. As the absolute values stored get larger, the spacing between adjacent numbers that can be exactly represented also gets larger.

How to get a value from a Pandas DataFrame and not the index and object type

Use the values attribute to return the values as a np array and then use [0] to get the first value:

In [4]:



I personally prefer to access the columns using subscript operators:

df.loc[df['Letters'] == 'C', 'Letters'].values[0]

This avoids issues where the column names can have spaces or dashes - which mean that accessing using ..

How to make ConstraintLayout work with percentage values?

With the new release of ConstraintLayout v1.1 you can now do the following:

app:layout_constraintWidth_percent="0.65" />

This will constrain the button to be 20% the height and 65% of the width of the parent view.

string to string array conversion in java

here is have convert simple string to string array using split method.

String [] stringArray="My Name is ABC".split(" ");



Getting rid of \n when using .readlines()

After opening the file, list comprehension can do this in one line:

newlist = [line.rstrip() for line in fh.readlines()]

Just remember to close your file afterwards.

Unable to auto-detect email address

it's pretty simple but tricky at the first time.
For example:
If my email is [email protected] type:

git config --global [email protected]


If my username is mrsuicidesheep type:

git config mrsuicidesheep

How to use local docker images with Minikube?

you can either reuse the docker shell, with eval $(minikube docker-env), alternatively, you can leverage on docker save | docker load across the shells.

MVC 4 @Scripts "does not exist"

Try this:

@section Scripts 
    Scripts.Render("~/bundles/jqueryval")  // <- without ampersand at the begin

Postgresql, update if row with some unique value exists, else insert

Firstly It tries insert. If there is a conflict on url column then it updates content and last_analyzed fields. If updates are rare this might be better option.

INSERT INTO URLs (url, content, last_analyzed)
SET content=%(content)s, last_analyzed = NOW();

What is the difference between a cer, pvk, and pfx file?

In Windows platform, these file types are used for certificate information. Normally used for SSL certificate and Public Key Infrastructure (X.509).

  • CER files: CER file is used to store X.509 certificate. Normally used for SSL certification to verify and identify web servers security. The file contains information about certificate owner and public key. A CER file can be in binary (ASN.1 DER) or encoded with Base-64 with header and footer included (PEM), Windows will recognize either of these layout.
  • PVK files: Stands for Private Key. Windows uses PVK files to store private keys for code signing in various Microsoft products. PVK is proprietary format.
  • PFX files Personal Exchange Format, is a PKCS12 file. This contains a variety of cryptographic information, such as certificates, root authority certificates, certificate chains and private keys. It’s cryptographically protected with passwords to keep private keys private and preserve the integrity of the root certificates. The PFX file is also used in various Microsoft products, such as IIS.

for more information visit:Certificate Files: .Cer x .Pvk x .Pfx

how to display none through code behind

try this

<div id="login_div" runat="server">

and on the code behind.

login_div.Style.Add("display", "none");

Creating a simple login form

<meta charset="utf-8">
<title>Best Login Page design in html and css</title>
<style type="text/css">
body {
background-color: #f4f4f4;
color: #5a5656;
font-family: 'Open Sans', Arial, Helvetica, sans-serif;
font-size: 16px;
line-height: 1.5em;
a { text-decoration: none; }
h1 { font-size: 1em; }
h1, p {
margin-bottom: 10px;
strong {
font-weight: bold;
.uppercase { text-transform: uppercase; }

/* ---------- LOGIN ---------- */
#login {
margin: 50px auto;
width: 300px;
form fieldset input[type="text"], input[type="password"] {
background-color: #e5e5e5;
border: none;
border-radius: 3px;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
color: #5a5656;
font-family: 'Open Sans', Arial, Helvetica, sans-serif;
font-size: 14px;
height: 50px;
outline: none;
padding: 0px 10px;
width: 280px;
form fieldset input[type="submit"] {
background-color: #008dde;
border: none;
border-radius: 3px;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
color: #f4f4f4;
cursor: pointer;
font-family: 'Open Sans', Arial, Helvetica, sans-serif;
height: 50px;
text-transform: uppercase;
width: 300px;
form fieldset a {
color: #5a5656;
font-size: 10px;
form fieldset a:hover { text-decoration: underline; }
.btn-round {
background-color: #5a5656;
border-radius: 50%;
-moz-border-radius: 50%;
-webkit-border-radius: 50%;
color: #f4f4f4;
display: block;
font-size: 12px;
height: 50px;
line-height: 50px;
margin: 30px 125px;
text-align: center;
text-transform: uppercase;
width: 50px;
.facebook-before {
background-color: #0064ab;
border-radius: 3px 0px 0px 3px;
-moz-border-radius: 3px 0px 0px 3px;
-webkit-border-radius: 3px 0px 0px 3px;
color: #f4f4f4;
display: block;
float: left;
height: 50px;
line-height: 50px;
text-align: center;
width: 50px;
.facebook {
background-color: #0079ce;
border: none;
border-radius: 0px 3px 3px 0px;
-moz-border-radius: 0px 3px 3px 0px;
-webkit-border-radius: 0px 3px 3px 0px;
color: #f4f4f4;
cursor: pointer;
height: 50px;
text-transform: uppercase;
width: 250px;
.twitter-before {
background-color: #189bcb;
border-radius: 3px 0px 0px 3px;
-moz-border-radius: 3px 0px 0px 3px;
-webkit-border-radius: 3px 0px 0px 3px;
color: #f4f4f4;
display: block;
float: left;
height: 50px;
line-height: 50px;
text-align: center;
width: 50px;
.twitter {
background-color: #1bb2e9;
border: none;
border-radius: 0px 3px 3px 0px;
-moz-border-radius: 0px 3px 3px 0px;
-webkit-border-radius: 0px 3px 3px 0px;
color: #f4f4f4;
cursor: pointer;
height: 50px;
text-transform: uppercase;
width: 250px;
<div id="login">
<h1><strong>Welcome.</strong> Please login.</h1>
<form action="javascript:void(0);" method="get">
<p><input type="text" required value="Username" onBlur="if(this.value=='')this.value='Username'" onFocus="if(this.value=='Username')this.value='' "></p>
<p><input type="password" required value="Password" onBlur="if(this.value=='')this.value='Password'" onFocus="if(this.value=='Password')this.value='' "></p>
<p><a href="#">Forgot Password?</a></p>
<p><input type="submit" value="Login"></p>
<p><span class="btn-round">or</span></p>
<a class="facebook-before"></a>
<button class="facebook">Login Using Facbook</button>
<a class="twitter-before"></a>
<button class="twitter">Login Using Twitter</button>
</div> <!-- end login -->

How to export collection to CSV in MongoDB?

Below command used to export collection to CSV format.

Note: naag is database, employee1_json is a collection.

mongoexport --db naag--collection employee1_json --type csv --out /home/orienit/work/mongodb/employee1_csv_op1

Lua String replace


name = "^aH^ai"
name = name:gsub("%^a", "")

See also:

Easiest way to convert month name to month number in JS ? (Jan = 01)

One more way to do the same

month1 = month1.toLowerCase();
var months = ["jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec"];
month1 = months.indexOf(month1);

Equivalent VB keyword for 'break'

Exit [construct], and intelisense will tell you which one(s) are valid in a particular place.

Live-stream video from one android phone to another over WiFi

I did work on something like this once, but sending a video and playing it in real time is a really complex thing. I suggest you work with PNG's only. In my implementation What i did was capture PNGs using the host camera and then sending them over the network to the client, Which will display the image as soon as received and request the next image from the host. Since you are on wifi that communication will be fast enough to get around 8-10 images per-second(approximation only, i worked on Bluetooth). So this will look like a continuous video but with much less effort. For communication you may use UDP sockets(Faster and less complex) or DLNA (Not sure how that works).

Getting the base url of the website and globally passing it to twig in Symfony 2

Why do you need to get this root url ? Can't you generate directly absolute URL's ?

{{ url('_demo_hello', { 'name': 'Thomas' }) }}

This Twig code will generate the full http:// url to the _demo_hello route.

In fact, getting the base url of the website is only getting the full url of the homepage route :

{{ url('homepage') }}

(homepage, or whatever you call it in your routing file).

How do I get the total number of unique pairs of a set in the database?

TLDR; The formula is n(n-1)/2 where n is the number of items in the set.


To find the number of unique pairs in a set, where the pairs are subject to the commutative property (AB = BA), you can calculate the summation of 1 + 2 + ... + (n-1) where n is the number of items in the set.

The reasoning is as follows, say you have 4 items:


The number of items that can be paired with A is 3, or n-1:


It follows that the number of items that can be paired with B is n-2 (because B has already been paired with A):


and so on...

(n-1) + (n-2) + ... + (n-(n-1))

which is the same as

1 + 2 + ... + (n-1)



javascript getting my textbox to display a variable

Even if this is already answered (1 year ago) you could also let the fields be calculated automatically.


        <td><input type="text" value="" ></td>
        <td><input type="text" class="class_name" placeholder="bla bla"/></td>
        <td><input type="text" value="" ></td>
        <td><input type="text" class="class_name" placeholder="bla bla."/></td>

The script

            function calculateSum(){
                var sum=0;
                    if(!isNaN(this.value) && this.value.length!=0){
                    else if(isNaN(this.value)) {
                        alert("Maybe an alert if they type , instead of .");

Android Google Maps API V2 Zoom to Current Location

youmap.animateCamera(CameraUpdateFactory.newLatLngZoom(currentlocation, 16));

16 is the zoom level

'this' implicitly has type 'any' because it does not have a type annotation

The error is indeed fixed by inserting this with a type annotation as the first callback parameter. My attempt to do that was botched by simultaneously changing the callback into an arrow-function:

foo.on('error', (this: Foo, err: any) => { // DON'T DO THIS

It should've been this:

foo.on('error', function(this: Foo, err: any) {

or this:

foo.on('error', function(this: typeof foo, err: any) {

A GitHub issue was created to improve the compiler's error message and highlight the actual grammar error with this and arrow-functions.

Access Controller method from another controller in Laravel 5

This approach also works with same hierarchy of Controller files:

$printReport = new PrintReportController;


How to compile C++ under Ubuntu Linux?

You should use g++, not gcc, to compile C++ programs.

For this particular program, I just typed

make avishay

and let make figure out the rest. Gives your executable a decent name, too, instead of a.out.

Newline in JLabel

JLabel is actually capable of displaying some rudimentary HTML, which is why it is not responding to your use of the newline character (unlike, say, System.out).

If you put in the corresponding HTML and used <BR>, you would get your newlines.

How do I show running processes in Oracle DB?

After looking at sp_who, Oracle does not have that ability per se. Oracle has at least 8 processes running which run the db. Like RMON etc.

You can ask the DB which queries are running as that just a table query. Look at the V$ tables.

Quick Example:

FROM v$session_longops
WHERE sofar != totalwork;

Send file via cURL from form POST in PHP

Here is my solution, i have been reading a lot of post and they was really helpfull, finaly i build a code for small files, with cUrl and Php, that i think its really usefull.

public function postFile()

        $file_url = "test.txt";  //here is the file route, in this case is on same directory but you can set URL too like ""
        $eol = "\r\n"; //default line-break for mime type
        $BOUNDARY = md5(time()); //random boundaryid, is a separator for each param on my post curl function
        $BODY=""; //init my curl body
        $BODY.= '--'.$BOUNDARY. $eol; //start param header
        $BODY .= 'Content-Disposition: form-data; name="sometext"' . $eol . $eol; // last Content with 2 $eol, in this case is only 1 content.
        $BODY .= "Some Data" . $eol;//param data in this case is a simple post data and 1 $eol for the end of the data
        $BODY.= '--'.$BOUNDARY. $eol; // start 2nd param,
        $BODY.= 'Content-Disposition: form-data; name="somefile"; filename="test.txt"'. $eol ; //first Content data for post file, remember you only put 1 when you are going to add more Contents, and 2 on the last, to close the Content Instance
        $BODY.= 'Content-Type: application/octet-stream' . $eol; //Same before row
        $BODY.= 'Content-Transfer-Encoding: base64' . $eol . $eol; // we put the last Content and 2 $eol,
        $BODY.= chunk_split(base64_encode(file_get_contents($file_url))) . $eol; // we write the Base64 File Content and the $eol to finish the data,
        $BODY.= '--'.$BOUNDARY .'--' . $eol. $eol; // we close the param and the post width "--" and 2 $eol at the end of our boundary header.

        $ch = curl_init(); //init curl
        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
                         'X_PARAM_TOKEN : 71e2cb8b-42b7-4bf0-b2e8-53fbd2f578f9' //custom header for my api validation you can get it from $_SERVER["HTTP_X_PARAM_TOKEN"] variable
                         ,"Content-Type: multipart/form-data; boundary=".$BOUNDARY) //setting our mime type for make it work on $_FILE variable
        curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/1.0 (Windows NT 6.1; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0'); //setting our user agent
        curl_setopt($ch, CURLOPT_URL, ""); //setting our api post url
        curl_setopt($ch, CURLOPT_COOKIEJAR, $BOUNDARY.'.txt'); //saving cookies just in case we want
        curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1); // call return content
        curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1); navigate the endpoint
        curl_setopt($ch, CURLOPT_POST, true); //set as post
        curl_setopt($ch, CURLOPT_POSTFIELDS, $BODY); // set our $BODY 

        $response = curl_exec($ch); // start curl navigation

     print_r($response); //print response


With this we shoud be get on the "" the following vars posted You can easly test with this script, and you should be recive this debugs on the function postFile() at the last row

print_r($response); //print response

public function getPostFile()

    echo "\n\n_SERVER\n";
    echo "<pre>";
    echo "/<pre>";
    echo "_POST\n";
    echo "<pre>";
    echo "/<pre>";
    echo "_FILES\n";
    echo "<pre>";
    echo "/<pre>";

Here you are it should be work good, could be better solutions but this works and is really helpfull to understand how the Boundary and multipart/from-data mime works on php and curl library,

My Best Reggards,

my apologies about my english but isnt my native language.

How can the default node version be set using NVM?

Lets say to want to make default version as 10.19.0.

nvm alias default v10.19.0

But it will give following error

! WARNING: Version 'v10.19.0' does not exist.
default -> v10.19.0 (-> N/A)

In That case you need to run two commands in the following order

# Install the version that you would like 
nvm install 10.19.0

# Set 10.19.0 (or another version) as default
nvm alias default 10.19.0

Django DB Settings 'Improperly Configured' Error

In 2017 with django 1.11.5 and python 3.6 (from the comment this also works with Python 2.7):

import django
import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")

The .py in which you put this code should be in mysite (the parent one)

How to select specific columns in laravel eloquent

By using all() method we can select particular columns from table like as shown below.

ModelName::all('column1', 'column2', 'column3');

Note: Laravel 5.4

How to style UITextview to like Rounded Rect text field?

I don't think that it is possible. but you can do UITableView(grouped) with 1 section and 1 empty cell and use it as a container for your UITextView.

Adding div element to body or document in JavaScript

You can make your div HTML code and set it directly into body(Or any element) with following code:

var divStr = '<div class="text-warning">Some html</div>';
document.getElementsByTagName('body')[0].innerHTML += divStr;

javascript cell number validation

<script type="text/javascript">
    function MobileNoValidation()
       var phno=/^\d{10}$/
        alert("Mobile No Should Not Be Empty");
       else if(!textMobileNo.value.match(phno))
        alert("Mobile no must be ten digit");
        alert("valid Mobile No");

SQL INSERT INTO from multiple tables

Here is an short extension for 3 or more tables to the answer of D Stanley:

INSERT INTO other_table (name, age, sex, city, id, number, nationality)
SELECT name, age, sex, city,, number, n.nationality
FROM table_1 p
INNER JOIN table_2 a ON =
INNER JOIN table_3 b ON =
INNER JOIN table_n x ON =

Restricting input to textbox: allowing only numbers and decimal point

I observed that for all the answers provided here, the things are not working if we select some portion of the text in textbox and try to overwrite that part. So I modified the function which is as below:

    <SCRIPT language=Javascript>
       function isNumberKey(evt)
         var charCode = (evt.which) ? evt.which : event.keyCode;

if (charCode != 46 && charCode > 31 && (charCode < 48 || charCode > 57))
        return false;
 if (charCode == 46 && evt.srcElement.value.split('.').length>1 )

        return false;


          return true;

  if(evt.srcElement.value.split('.').length>1 && evt.srcElement.value.split('.')[1].length==2)

     return false;

    return true;

    <INPUT id="txtChar" onkeypress="return isNumberKey(event)" 
           type="text" name="txtChar">

"elseif" syntax in JavaScript

Just add a space:

if (...) {

} else if (...) {

} else {


Creating all possible k combinations of n items in C++

I have written a class in C# to handle common functions for working with the binomial coefficient, which is the type of problem that your problem falls under. It performs the following tasks:

  1. Outputs all the K-indexes in a nice format for any N choose K to a file. The K-indexes can be substituted with more descriptive strings or letters. This method makes solving this type of problem quite trivial.

  2. Converts the K-indexes to the proper index of an entry in the sorted binomial coefficient table. This technique is much faster than older published techniques that rely on iteration. It does this by using a mathematical property inherent in Pascal's Triangle. My paper talks about this. I believe I am the first to discover and publish this technique.

  3. Converts the index in a sorted binomial coefficient table to the corresponding K-indexes. I believe it is also faster than the other solutions.

  4. Uses Mark Dominus method to calculate the binomial coefficient, which is much less likely to overflow and works with larger numbers.

  5. The class is written in .NET C# and provides a way to manage the objects related to the problem (if any) by using a generic list. The constructor of this class takes a bool value called InitTable that when true will create a generic list to hold the objects to be managed. If this value is false, then it will not create the table. The table does not need to be created in order to perform the 4 above methods. Accessor methods are provided to access the table.

  6. There is an associated test class which shows how to use the class and its methods. It has been extensively tested with 2 cases and there are no known bugs.

To read about this class and download the code, see Tablizing The Binomial Coeffieicent.

It should be pretty straight forward to port the class over to C++.

The solution to your problem involves generating the K-indexes for each N choose K case. For example:

int NumPeople = 10;
int N = TotalColumns;
// Loop thru all the possible groups of combinations.
for (int K = N - 1; K < N; K++)
   // Create the bin coeff object required to get all
   // the combos for this N choose K combination.
   BinCoeff<int> BC = new BinCoeff<int>(N, K, false);
   int NumCombos = BinCoeff<int>.GetBinCoeff(N, K);
   int[] KIndexes = new int[K];
   BC.OutputKIndexes(FileName, DispChars, "", " ", 60, false);
   // Loop thru all the combinations for this N choose K case.
   for (int Combo = 0; Combo < NumCombos; Combo++)
      // Get the k-indexes for this combination, which in this case
      // are the indexes to each person in the problem set.
      BC.GetKIndexes(Loop, KIndexes);
      // Do whatever processing that needs to be done with the indicies in KIndexes.

The OutputKIndexes method can also be used to output the K-indexes to a file, but it will use a different file for each N choose K case.

How to display a range input slider vertically

Its very simple. I had implemented using -webkit-appearance: slider-vertical, It worked in chorme, Firefox, Edge

<input type="range">
    writing-mode: bt-lr; /* IE */
    -webkit-appearance: slider-vertical; /* WebKit */
    width: 50px;
    height: 200px;
    padding: 0 24px;
    outline: none;

How to add http:// if it doesn't exist in the URL

nickf's solution modified:

function addhttp($url) {
    if (!preg_match("@^https?://@i", $url) && !preg_match("@^ftps?://@i", $url)) {
        $url = "http://" . $url;
    return $url;

Where does Internet Explorer store saved passwords?

I found the answer. IE stores passwords in two different locations based on the password type:

  • Http-Auth: %APPDATA%\Microsoft\Credentials, in encrypted files
  • Form-based: HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IntelliForms\Storage2, encrypted with the url

From a very good page on

Starting from version 7.0 of Internet Explorer, Microsoft completely changed the way that passwords are saved. In previous versions (4.0 - 6.0), all passwords were saved in a special location in the Registry known as the "Protected Storage". In version 7.0 of Internet Explorer, passwords are saved in different locations, depending on the type of password. Each type of passwords has some limitations in password recovery:

  • AutoComplete Passwords: These passwords are saved in the following location in the Registry: HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IntelliForms\Storage2 The passwords are encrypted with the URL of the Web sites that asked for the passwords, and thus they can only be recovered if the URLs are stored in the history file. If you clear the history file, IE PassView won't be able to recover the passwords until you visit again the Web sites that asked for the passwords. Alternatively, you can add a list of URLs of Web sites that requires user name/password into the Web sites file (see below).

  • HTTP Authentication Passwords: These passwords are stored in the Credentials file under Documents and Settings\Application Data\Microsoft\Credentials, together with login passwords of LAN computers and other passwords. Due to security limitations, IE PassView can recover these passwords only if you have administrator rights.

In my particular case it answers the question of where; and I decided that I don't want to duplicate that. I'll continue to use CredRead/CredWrite, where the user can manage their passwords from within an established UI system in Windows.

Scroll Position of div with "overflow: auto"

You need to use the scrollTop property.


Using atan2 to find angle between two vectors

You don't have to use atan2 to calculate the angle between two vectors. If you just want the quickest way, you can use dot(v1, v2)=|v1|*|v2|*cos A to get

A = Math.acos( dot(v1, v2)/(v1.length()*v2.length()) );

Cleanest way to build an SQL string in Java

For arbitrary SQL, use jOOQ. jOOQ currently supports SELECT, INSERT, UPDATE, DELETE, TRUNCATE, and MERGE. You can create SQL like this:

String sql1 = DSL.using(SQLDialect.MYSQL)  
                 .select(A, B, C)

String sql2 = DSL.using(SQLDialect.MYSQL)  
                 .values(A, 1)
                 .values(B, 2)

String sql3 = DSL.using(SQLDialect.MYSQL)  
                 .set(A, 1)
                 .set(B, 2)

Instead of obtaining the SQL string, you could also just execute it, using jOOQ. See

(Disclaimer: I work for the company behind jOOQ)

how do I check in bash whether a file was created more than x time ago?

Creation time isn't stored.

What are stored are three timestamps (generally, they can be turned off on certain filesystems or by certain filesystem options):

  • Last access time
  • Last modification time
  • Last change time

a "Change" to the file is counted as permission changes, rename etc. While the modification is contents only.

How to Validate a DateTime in C#?

Here's another variation of the solution that returns true if the string can be converted to a DateTime type, and false otherwise.

public static bool IsDateTime(string txtDate)
    DateTime tempDate;
    return DateTime.TryParse(txtDate, out tempDate);

Split long commands in multiple lines through Windows batch file

It seems however that splitting in the middle of the values of a for loop doesn't need a caret(and actually trying to use one will be considered a syntax error). For example,

for %n in (hello
bye) do echo %n

Note that no space is even needed after hello or before bye.

What are FTL files

'ftl' stands for freemarker. It combines server side objects and view side (HTML/JQuery) contents into a single viewable template on the client browser.
Some documentation which might help:


In what cases will HTTP_REFERER be empty

It will also be empty if the new Referrer Policy standard draft is used to prevent that the referer header is sent to the request origin. Example:

<meta name="referrer" content="none">

Although Chrome and Firefox have already implemented a draft version of the Referrer Policy, you should be careful with it because for example Chrome expects no-referrer instead of none (and I have seen also never somewhere).

There is already an object named in the database

After more than an hour of not getting any results I tried another approach, not using migrations but I did a schema compare.

In Visual Studio -> Tools -> SQL Server -> New Schema Comparison

First I created a new completely new database with EF migrations. Than I did a compare, comparing the new database with the one I wanted to update. Finally generated a migration script, and I could perform a schema update.

Logging levels - Logback - rule-of-thumb to assign log levels

I answer this coming from a component-based architecture, where an organisation may be running many components that may rely on each other. During a propagating failure, logging levels should help to identify both which components are affected and which are a root cause.

  • ERROR - This component has had a failure and the cause is believed to be internal (any internal, unhandled exception, failure of encapsulated dependency... e.g. database, REST example would be it has received a 4xx error from a dependency). Get me (maintainer of this component) out of bed.

  • WARN - This component has had a failure believed to be caused by a dependent component (REST example would be a 5xx status from a dependency). Get the maintainers of THAT component out of bed.

  • INFO - Anything else that we want to get to an operator. If you decide to log happy paths then I recommend limiting to 1 log message per significant operation (e.g. per incoming http request).

For all log messages be sure to log useful context (and prioritise on making messages human readable/useful rather than having reams of "error codes")

  • DEBUG (and below) - Shouldn't be used at all (and certainly not in production). In development I would advise using a combination of TDD and Debugging (where necessary) as opposed to polluting code with log statements. In production, the above INFO logging, combined with other metrics should be sufficient.

A nice way to visualise the above logging levels is to imagine a set of monitoring screens for each component. When all running well they are green, if a component logs a WARNING then it will go orange (amber) if anything logs an ERROR then it will go red.

In the event of an incident you should have one (root cause) component go red and all the affected components should go orange/amber.

git revert back to certain commit

You can revert all your files under your working directory and index by typing following this command

git reset --hard <SHAsum of your commit>

You can also type

git reset --hard HEAD #your current head point


git reset --hard HEAD^ #your previous head point

Hope it helps

C: Run a System Command and Get Output?

You need some sort of Inter Process Communication. Use a pipe or a shared buffer.

How to insert an item at the beginning of an array in PHP?

In case of an associative array or numbered array where you do not want to change the array keys:

$firstItem = array('foo' => 'bar');

$arr = $firstItem + $arr;

array_merge does not work as it always reindexes the array.

Fatal error: Call to a member function bind_param() on boolean

This particular error has very little to do with the actual error. Here is my similar experience and the solution...

I had a table that I use in my statement with |database-name|.login composite name. I thought this wouldn't be a problem. It was the problem indeed. Enclosing it inside square brackets solved my problem ([|database-name|].[login]). So, the problem is MySQL preserved words (other way around)... make sure your columns too are not failing to this type of error scenario...


You Could try the other format for the case statement

CASE WHEN Product.type_id = 10
  Select Statement
  Other select statement

FROM Product 
WHERE Product.product_id = $pid

See for more information.

Split Div Into 2 Columns Using CSS

Another way to do this is to add overflow:hidden; to the parent element of the floated elements.

overflow:hidden will make the element grow to fit in floated elements.

This way, it can all be done in css rather than adding another html element.

Any way to break if statement in PHP?

Answering to your question whether that is achievable or not, then yes that is achievable using "goto" operator of php.

But ethically, its not a good practice to use "goto" and of there is any need to use goto then this means that code need to be reconstructed such that requirement of goto can be removed.

According to the sample code you posted above, it can be clearly seen that the code can be reconstructed and the code that is no more required can be either deleted or commented (if possibility is there for use in future).

"Could not find a version that satisfies the requirement opencv-python"

It happened with me on Windows, pip was not able to install opencv-python==

Later found out that it was due to the Python version, Python 3.7 has some issue with not getting linked to

Downgraded to Python 3.6 and it worked with:

pip3 install opencv-python

Insert current date into a date column using T-SQL?

Couple of ways. Firstly, if you're adding a row each time a [de]activation occurs, you can set the column default to GETDATE() and not set the value in the insert. Otherwise,

UPDATE TableName SET [ColumnName] = GETDATE() WHERE UserId = @userId

Fade Effect on Link Hover?

Nowadays people are just using CSS3 transitions because it's a lot easier than messing with JS, browser support is reasonably good and it's merely cosmetic so it doesn't matter if it doesn't work.

Something like this gets the job done:

a {
  /* First we need to help some browsers along for this to work.
     Just because a vendor prefix is there, doesn't mean it will
     work in a browser made by that vendor either, it's just for
     future-proofing purposes I guess. */
  /* ...and now for the proper property */
a:hover { color:red; }

You can also transition specific CSS properties with different timings and easing functions by separating each declaration with a comma, like so:

a {
  color:blue; background:white;
  -o-transition:color .2s ease-out, background 1s ease-in;
  -ms-transition:color .2s ease-out, background 1s ease-in;
  -moz-transition:color .2s ease-out, background 1s ease-in;
  -webkit-transition:color .2s ease-out, background 1s ease-in;
  /* ...and now override with proper CSS property */
  transition:color .2s ease-out, background 1s ease-in;
a:hover { color:red; background:yellow; }

Demo here

How to install wkhtmltopdf on a linux based (shared hosting) web server

Place the wkhtmltopdf executable on the server and chmod it +x.

Create an executable shell script containing:

export HOME="$PWD"
export LD_LIBRARY_PATH="$PWD/lib/"
exec $@ 2>/dev/null
#exec $@ 2>&1 # debug mode

Download needed shared objects for that architecture and place them an a folder named "lib":

  • lib/
  • lib/
  • lib/
  • lib/
  • lib/ lib/
  • lib/ lib/
  • lib/ lib/
  • lib/
  • lib/
  • lib/
  • lib/
  • lib/ lib/

(some of them are symlinks)

… and you're ready to go:

./ ./wkhtmltopdf-amd64 --page-size A4 --disable-internal-links --disable-external-links "" out.pdf

If you experience font problems like squares for all the characters, define TrueType fonts explicitly:

@font-face {
  font-family:Trebuchet MS;

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

try doing str.replace(/[^\w]/); It will replace all the non-alphabets and numbers from your string!

Edit 1: str.replace(/[^\w]/g, ' ')

Regex that matches integers in between whitespace or start/end of string only

I would add this as a comment to the other good answers, but I need more reputation to do so. Be sure to allow for scientific notation if necessary, i.e. 3e4 = 30000. This is default behavior in many languages. I found the following regex to work:

//          ^^              If 'e' is present to denote exp notation, get it
//             ^^^^^          along with optional sign of exponent
//                  ^^^       and the exponent itself
//        ^            ^^     The entire exponent expression is optional

In Javascript, how do I check if an array has duplicate values?

Well I did a bit of searching around the internet for you and I found this handy link.

Easiest way to find duplicate values in a JavaScript array

You can adapt the sample code that is provided in the above link, courtesy of "swilliams" to your solution.

How to merge multiple lists into one list in python?

import itertools
ab = itertools.chain(['it'], ['was'], ['annoying'])

Just another method....

What is the list of supported languages/locales on Android?


public static final Locale  CANADA  Locale constant for en_CA.
public static final Locale  CANADA_FRENCH   Locale constant for fr_CA.
public static final Locale  CHINA   Locale constant for zh_CN.
public static final Locale  CHINESE Locale constant for zh.
public static final Locale  ENGLISH Locale constant for en.
public static final Locale  FRANCE  Locale constant for fr_FR.
public static final Locale  FRENCH  Locale constant for fr.
public static final Locale  GERMAN  Locale constant for de.
public static final Locale  GERMANY Locale constant for de_DE.
public static final Locale  ITALIAN Locale constant for it.
public static final Locale  ITALY   Locale constant for it_IT.
public static final Locale  JAPAN   Locale constant for ja_JP.
public static final Locale  JAPANESE    Locale constant for ja.
public static final Locale  KOREA   Locale constant for ko_KR.
public static final Locale  KOREAN  Locale constant for ko.
public static final Locale  PRC Locale constant for zh_CN.
public static final Locale  ROOT    Locale constant for the root locale.
public static final Locale  SIMPLIFIED_CHINESE  Locale constant for zh_CN.
public static final Locale  TAIWAN  Locale constant for zh_TW.
public static final Locale  TRADITIONAL_CHINESE Locale constant for zh_TW.
public static final Locale  UK  Locale constant for en_GB.
public static final Locale  US  Locale constant for en_US.

how to execute a scp command with the user name and password in one line

Using sshpass works best. To just include your password in scp use the ' ':

scp user1:'password' /var/www/dev/

ImageView rounded corners

  • May be you have found your solution but recently i found new library which allows you to create any many shape you want to set to the Image VIew.

    • Download the library from here
    • Define your Xml as :-
    • <com.makeramen.roundedimageview.RoundedImageView......... app:riv_corner_radius="Yourradiusdip"/>
    • And enjoy the coding.! this library i found is the best! thanks [I posted this answer later on but i recently used it and found it realy helpful]

How can I symlink a file in Linux?

(Because an ASCII picture is worth a thousand characters.)

An arrow may be a helpful mnemonic, especially since that's almost exactly how it looks in Emacs' dired.

And big picture so you don't get it confused with the Windows' version


ln -s target <- linkName


mklink linkName -> target

You could also look at these as

ln -s "to-here" <- "from-here"
mklink "from-here" -> "to-here"

The from-here should not exist yet, it is to be created, while the to-here should already exist (IIRC).

(I always get mixed up on whether various commands and arguments should involve a pre-existing location, or one to be made.)

EDIT: It's still sinking in slowly for me; I have another way I've written in my notes.

ln -s (target exists) (link is made)
mklink (link is made) (target exists)

Writing to an Excel spreadsheet

Try taking a look at the following libraries too:

xlwings - for getting data into and out of a spreadsheet from Python, as well as manipulating workbooks and charts

ExcelPython - an Excel add-in for writing user-defined functions (UDFs) and macros in Python instead of VBA

Concatenate two NumPy arrays vertically

a = np.array([1,2,3])
b = np.array([4,5,6])

works just as well as

np.array([[1,2,3], [4,5,6]])

Regardless of whether it is a list of lists or a list of 1d arrays, np.array tries to create a 2d array.

But it's also a good idea to understand how np.concatenate and its family of stack functions work. In this context concatenate needs a list of 2d arrays (or any anything that np.array will turn into a 2d array) as inputs.

np.vstack first loops though the inputs making sure they are at least 2d, then does concatenate. Functionally it's the same as expanding the dimensions of the arrays yourself.

np.stack is a new function that joins the arrays on a new dimension. Default behaves just like np.array.

Look at the code for these functions. If written in Python you can learn quite a bit. For vstack:

return _nx.concatenate([atleast_2d(_m) for _m in tup], 0)

android - listview get item view by position

Preferred way to change the appearance/whatever of row views once the ListView is drawn is to change something in the data ListView draws from (the array of objects that is passed into your Adapter) and make sure to account for that in your getView() function, then redraw the ListView by calling


EDIT: while there is a way to do this, if you need to do this chances are doing something wrong. While are few edge cases I can think about, generally using notifyDataSetChanged() and other built in mechanisms is a way to go.

EDIT 2: One of the common mistakes people make is trying to come up with their own way to respond to user clicking/selecting a row in the ListView, as in one of the comments to this post. There is an existing way to do this. Here's how:

mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    /* Parameters
    parent:     The AdapterView where the click happened.
    view:       The view within the AdapterView that was clicked (this will be a view provided by the adapter)
    position:   The position of the view in the adapter.
    id:         The row id of the item that was clicked. */
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        //your code here

ListView has a lot of build-in functionality and there is no need to reinvent the wheel for simpler cases. Since ListView extends AdapterView, you can set the same Listeners, such as OnItemClickListener as in the example above.

LINQ: combining join and group by

We did it like this:

from p in Products                         
join bp in BaseProducts on p.BaseProductId equals bp.Id                    
where !string.IsNullOrEmpty(p.SomeId) && p.LastPublished >= lastDate                         
group new { p, bp } by new { p.SomeId } into pg    
let firstproductgroup = pg.FirstOrDefault()
let product = firstproductgroup.p
let baseproduct = firstproductgroup.bp
let minprice = pg.Min(m => m.p.Price)
let maxprice = pg.Max(m => m.p.Price)
select new ProductPriceMinMax
SomeId = product.SomeId,
BaseProductName = baseproduct.Name,
CountryCode = product.CountryCode,
MinPrice = minprice, 
MaxPrice = maxprice

EDIT: we used the version of AakashM, because it has better performance

How to analyse the heap dump using jmap in java

VisualVm does not come with Apple JDK. You can use VisualVM Mac Application bundle(dmg) as a separate application, to compensate for that.

Can't escape the backslash with regex?

The backslash \ is the escape character for regular expressions. Therefore a double backslash would indeed mean a single, literal backslash.

\ (backslash) followed by any of [\^$.|?*+(){} escapes the special character to suppress its special meaning.

ref :

How to Execute stored procedure from SQL Plus?

You have two options, a PL/SQL block or SQL*Plus bind variables:

var z number

execute  my_stored_proc (-1,2,0.01,:z)

print z

JSON parse error: Can not construct instance of java.time.LocalDate: no String-argument constructor/factory method to deserialize from String value

I had a similar issue which i solved by making two changes

  1. added below entry in application.yaml file

    spring: jackson: serialization.write_dates_as_timestamps: false

  2. add below two annotations in pojo

    1. @JsonDeserialize(using = LocalDateDeserializer.class)
    2. @JsonSerialize(using = LocalDateSerializer.class)

    sample example

    import com.fasterxml.jackson.databind.annotation.JsonDeserialize; import com.fasterxml.jackson.databind.annotation.JsonSerialize; public class Customer { //your fields ... @JsonDeserialize(using = LocalDateDeserializer.class) @JsonSerialize(using = LocalDateSerializer.class) protected LocalDate birthdate; }

then the following json requests worked for me

  1. sample request format as string

{ "birthdate": "2019-11-28" }

  1. sample request format as array

{ "birthdate":[2019,11,18] }

Hope it helps!!

pandas python how to count the number of records or rows in a dataframe

Simple method to get the records count:


How to remove the focus from a TextBox in WinForms?

You can try:

textBox1.Enable = false;

Unix shell script find out which directory the script file resides?

The best answer for this question was answered here:
Getting the source directory of a Bash script from within

And it is:

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

One-liner which will give you the full directory name of the script no matter where it is being called from.

To understand how it works you can execute the following script:


while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
  TARGET="$(readlink "$SOURCE")"
  if [[ $TARGET == /* ]]; then
    echo "SOURCE '$SOURCE' is an absolute symlink to '$TARGET'"
    DIR="$( dirname "$SOURCE" )"
    echo "SOURCE '$SOURCE' is a relative symlink to '$TARGET' (relative to '$DIR')"
    SOURCE="$DIR/$TARGET" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
echo "SOURCE is '$SOURCE'"
RDIR="$( dirname "$SOURCE" )"
DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
if [ "$DIR" != "$RDIR" ]; then
  echo "DIR '$RDIR' resolves to '$DIR'"
echo "DIR is '$DIR'"

Error: "Adb connection Error:An existing connection was forcibly closed by the remote host"

Looks like the installed driver was in bad state. Here is what I did to make it work:

  1. Delete the device from Device Manager.
  2. Rescan for hardware changes.
  3. "Slate 21" will show up with "Unknown driver" status.
  4. Click on "Update Driver" and select /extras/google/usb_driver
  5. Device Manager will find the driver and warn you about installing it. Select "Yes."

This time the device got installed properly.

Note that I didn't have to modify winusb.inf file or update any other driver.

Hope this helps.

Sass .scss: Nesting and multiple classes?

Christoph's answer is perfect. Sometimes however you may want to go more classes up than one. In this case you could try the @at-root and #{} css features which would enable two root classes to sit next to each other using &.

This wouldn't work (due to the nothing before & rule):

container {_x000D_
    .desc& {_x000D_
      background: blue;_x000D_
    .hello {_x000D_

But this would (using @at-root plus #{&}):

container {_x000D_
    @at-root .desc#{&} {_x000D_
      background: blue;_x000D_
    .hello {_x000D_

How to change text color and console color in code::blocks?

system("COLOR 0A");'

where 0A is a combination of background and font color 0

Animate visibility modes, GONE and VISIBLE

Visibility change itself can be easy animated by overriding setVisibility method. Look at complete code:

public class SimpleViewAnimator extends FrameLayout
    private Animation inAnimation;
    private Animation outAnimation;

    public SimpleViewAnimator(Context context)

    public void setInAnimation(Animation inAnimation)
        this.inAnimation = inAnimation;

    public void setOutAnimation(Animation outAnimation)
        this.outAnimation = outAnimation;

    public void setVisibility(int visibility)
        if (getVisibility() != visibility)
            if (visibility == VISIBLE)
                if (inAnimation != null) startAnimation(inAnimation);
            else if ((visibility == INVISIBLE) || (visibility == GONE))
                if (outAnimation != null) startAnimation(outAnimation);


MySQL: #1075 - Incorrect table definition; autoincrement vs another key?

Identified this solution while reading this thread. Figured id post this for the next guy possibly.

When dealing with Laravel migration file from a package, I Ran into this issue.

My old value was


My new


Strange PostgreSQL "value too long for type character varying(500)"

By specifying the column as VARCHAR(500) you've set an explicit 500 character limit. You might not have done this yourself explicitly, but Django has done it for you somewhere. Telling you where is hard when you haven't shown your model, the full error text, or the query that produced the error.

If you don't want one, use an unqualified VARCHAR, or use the TEXT type.

varchar and text are limited in length only by the system limits on column size - about 1GB - and by your memory. However, adding a length-qualifier to varchar sets a smaller limit manually. All of the following are largely equivalent:

column_name VARCHAR(500)

column_name VARCHAR CHECK (length(column_name) <= 500) 

column_name TEXT CHECK (length(column_name) <= 500) 

The only differences are in how database metadata is reported and which SQLSTATE is raised when the constraint is violated.

The length constraint is not generally obeyed in prepared statement parameters, function calls, etc, as shown:

regress=> \x
Expanded display is on.
regress=> PREPARE t2(varchar(500)) AS SELECT $1;
regress=> EXECUTE t2( repeat('x',601) );
-[ RECORD 1 ]-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
?column? | xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

and in explicit casts it result in truncation:

regress=> SELECT repeat('x',501)::varchar(1);
-[ RECORD 1 ]
repeat | x

so I think you are using a VARCHAR(500) column, and you're looking at the wrong table or wrong instance of the database.

Stopping Docker containers by image name - Ubuntu

You could start the container setting a container name:

docker run -d --name <container-name> <image-name>

The same image could be used to spin up multiple containers, so this is a good way to start a container. Then you could use this container-name to stop, attach... the container:

docker exec -it <container-name> bash
docker stop <container-name>
docker rm <container-name>

How to force a list to be vertical using html css

Try putting display: block in the <li> tags instead of the <ul>

Getting an odd error, SQL Server query using `WITH` clause

It should be legal to put a semicolon directly before the WITH keyword.

405 method not allowed Web API

I was having exactly the same problem. I looked for two hours what was wrong with no luck until I realize my POST method was private instead of public .

Funny now seeing that error message is kind of generic. Hope it helps!

npm install private github repositories by dependency in package.json

Try this:

"dependencies" : {
  "name1" : "git://",
  "name2" : "git://"

You could also try this, where visionmedia/express is name/repo:

"dependencies" : {
   "express" : "visionmedia/express"

Or (if the npm package module exists):

"dependencies" : {
  "name": "*"

Taken from NPM docs

Can I prevent text in a div block from overflowing?

overflow: scroll ? Or auto. in the style attribute.

Installing Java 7 (Oracle) in Debian via apt-get

Managed to get answer after do some google..

echo "deb precise main" | tee -a /etc/apt/sources.list
echo "deb-src precise main" | tee -a /etc/apt/sources.list
apt-key adv --keyserver hkp:// --recv-keys EEA14886
apt-get update
# Java 7
apt-get install oracle-java7-installer
# For Java 8 command is:
apt-get install oracle-java8-installer

Recursively look for files with a specific extension

for file in "${LOCATION_VAR}"/*.zip
  echo "$file"

Can Rails Routing Helpers (i.e. mymodel_path(model)) be Used in Models?

(Edit: Forget my previous babble...)

Ok, there might be situations where you would go either to the model or to some other url... But I don't really think this belongs in the model, the view (or maybe the model) sounds more apropriate.

About the routes, as far as I know the routes is for the actions in controllers (wich usually "magically" uses a view), not directly to views. The controller should handle all requests, the view should present the results and the model should handle the data and serve it to the view or controller. I've heard a lot of people here talking about routes to models (to the point I'm allmost starting to beleave it), but as I understand it: routes goes to controllers. Of course a lot of controllers are controllers for one model and is often called <modelname>sController (e.g. "UsersController" is the controller of the model "User").

If you find yourself writing nasty amounts of logic in a view, try to move the logic somewhere more appropriate; request and internal communication logic probably belongs in the controller, data related logic may be placed in the model (but not display logic, which includes link tags etc.) and logic that is purely display related would be placed in a helper.

Is there a way to take the first 1000 rows of a Spark Dataframe?

Limit is very simple, example limit first 50 rows

val df_subset = data.limit(50)

C++ Remove new line from multiline string

The code removes all newlines from the string str.

O(N) implementation best served without comments on SO and with comments in production.

unsigned shift=0;
for (unsigned i=0; i<length(str); ++i){
    if (str[i] == '\n') {
        str[i-shift] = str[i];
str.resize(str.length() - shift);

css3 transition animation on load?

Very little Javascript is necessary:

window.onload = function() {
    document.body.className += " loaded";

Now the CSS:

.fadein {
    opacity: 0;
    -moz-transition: opacity 1.5s;
    -webkit-transition: opacity 1.5s;
    -o-transition: opacity 1.5s;
    transition: opacity 1.5s;

body.loaded .fadein {
    opacity: 1;

I know the question said "without Javascript", but I think it's worth pointing out that there is an easy solution involving one line of Javascript.

It could even be inline Javascript, something like that:

<body onload="document.body.className += ' loaded';" class="fadein">

That's all the JavaScript that's needed.

Unable to Build using MAVEN with ERROR - Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile

For me, I changed C:\apps\Java\jdk1.8_162\bin\javac.exe to C:\apps\Java\jdk1.8_162\bin\javacpl.exe Since there was no executable with that name in the bin folder. That worked.

Setting user agent of a java URLConnection

Off hand, setting the http.agent system property to "" might do the trick (I don't have the code in front of me).

You might get away with:

 System.setProperty("http.agent", "");

but that might require a race between you and initialisation of the URL protocol handler, if it caches the value at startup (actually, I don't think it does).

The property can also be set through JNLP files (available to applets from 6u10) and on the command line:


Or for wrapper commands:


JPA Query.getResultList() - use in a generic way

The above query returns the list of Object[]. So if you want to get the and s.something from the list then you need to iterate and cast that values for the corresponding classes.

JQuery: detect change in input field

You can use jQuery change() function

  //your codes

There are examples on how to use it on the API Page:

Bi-directional Map in Java?

There is no bidirectional map in the Java Standard API. Either you can maintain two maps yourself or use the BidiMap from Apache Collections.

Getting MAC Address

You can do this with psutil which is cross-platform:

import psutil
nics = psutil.net_if_addrs()
print [j.address for j in nics[i] for i in nics if i!="lo" and]

Oracle 10g: Extract data (select) from XML (CLOB Type)

You can try creating DBMS_XMLPARSER.parser object from the CLOB XML and get a DBMS_XMLDOM.DOMDocument object from it. Then use DBMS_XMLDOM package methods to get the value of any node.

   xml_            CLOB := 'X';
   p               DBMS_XMLPARSER.parser;
   doc_            DBMS_XMLDOM.DOMDocument;

      -- Convert the CLOB into a XML-document
      P := DBMS_XMLPARSER.newparser();
      -- Parse the clob and get the XML-document
      DBMS_XMLPARSER.parseclob(p, xml_);
      doc_ := DBMS_XMLPARSER.getDocument(p);

Then use the below methods to extract node value

DBMS_XMLDOM.getElementsByTagName(doc_, 'NodeName'); DBMS_XMLDOM.GetNodeValue(node_obj_);

Refer more about DBMS_XMLDOM methods here.

Removing the first 3 characters from a string

Use the substring method of the String class :

String removeCurrency=amount.getText().toString().substring(3);

How to add a border just on the top side of a UIView

My answer to a similar question: I personally prefer going down the category road on that one, since I want to be able to use it on any subclass of UIView.

How can I access Google Sheet spreadsheets only with Javascript?

Sorry, this is a lousy answer. Apparently this has been an issue for almost two years so don't hold your breath.

Here is the official request that you can "star"

Probably the closest you can come is rolling your own service with Google App Engine/Python and exposing whatever subset you need with your own JS library. Though I'd love to have a better solution myself.

How to convert HTML to PDF using iTextSharp

Here's the link I used as a guide. Hope this helps!

Converting HTML to PDF using ITextSharp

protected void Page_Load(object sender, EventArgs e)
            string strHtml = string.Empty;
            //HTML File path -
            string htmlFileName = Server.MapPath("~") + "\\files\\" + "ConvertHTMLToPDF.htm";
            //pdf file path. -
            string pdfFileName = Request.PhysicalApplicationPath + "\\files\\" + "ConvertHTMLToPDF.pdf";

            //reading html code from html file
            FileStream fsHTMLDocument = new FileStream(htmlFileName, FileMode.Open, FileAccess.Read);
            StreamReader srHTMLDocument = new StreamReader(fsHTMLDocument);
            strHtml = srHTMLDocument.ReadToEnd();

            strHtml = strHtml.Replace("\r\n", "");
            strHtml = strHtml.Replace("\0", "");

            CreatePDFFromHTMLFile(strHtml, pdfFileName);

            Response.Write("pdf creation successfully with password -");
        catch (Exception ex)
    public void CreatePDFFromHTMLFile(string HtmlStream, string FileName)
            object TargetFile = FileName;
            string ModifiedFileName = string.Empty;
            string FinalFileName = string.Empty;

            /* To add a Password to PDF - */
            TestPDF.HtmlToPdfBuilder builder = new TestPDF.HtmlToPdfBuilder(iTextSharp.text.PageSize.A4);
            TestPDF.HtmlPdfPage first = builder.AddPage();
            byte[] file = builder.RenderPdf();
            File.WriteAllBytes(TargetFile.ToString(), file);

            iTextSharp.text.pdf.PdfReader reader = new iTextSharp.text.pdf.PdfReader(TargetFile.ToString());
            ModifiedFileName = TargetFile.ToString();
            ModifiedFileName = ModifiedFileName.Insert(ModifiedFileName.Length - 4, "1");

            string password = "password";
            iTextSharp.text.pdf.PdfEncryptor.Encrypt(reader, new FileStream(ModifiedFileName, FileMode.Append), iTextSharp.text.pdf.PdfWriter.STRENGTH128BITS, password, "", iTextSharp.text.pdf.PdfWriter.AllowPrinting);
            if (File.Exists(TargetFile.ToString()))
            FinalFileName = ModifiedFileName.Remove(ModifiedFileName.Length - 5, 1);
            File.Copy(ModifiedFileName, FinalFileName);
            if (File.Exists(ModifiedFileName))

        catch (Exception ex)
            throw ex;

You can download the sample file. Just place the html you want to convert in the files folder and run. It will automatically generate the pdf file and place it in the same folder. But in your case, you can specify your html path in the htmlFileName variable.

How to check if X server is running?

I often need to run an X command on a server that is running many X servers, so the ps based answers do not work. Naturally, $DISPLAY has to be set appropriately. To check that that is valid, use xset q in some fragment like:

if ! xset q &>/dev/null; then
    echo "No X server at \$DISPLAY [$DISPLAY]" >&2
    exit 1


Some people find that xset can pause for a annoying amount of time before deciding that $DISPLAY is not pointing at a valid X server (often when tcp/ip is the transport). The fix of course is to use timeout to keep the pause amenable, 1 second say.

if ! timeout 1s xset q &>/dev/null; then

Centering the image in Bootstrap

.img-responsive {
     margin: 0 auto;

you can write like above code in your document so no need to add one another class in image tag.

What is log4j's default log file dumping path

You can see the log info in the console view of your IDE if you are not using any log4j properties to generate log file. You can define in your project so that those properties would be used to generate log file. A quick sample is listed below.

# Global logging configuration
log4j.rootLogger=DEBUG, stdout, R

# SQL Map logging configuration... MapClientDelegate=INFO


# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n


# Keep one backup file

log4j.appender.R.layout.ConversionPattern=%d %5p [%t] (%F\:%L) - %m%n

Get the last non-empty cell in a column in Google Sheets

Here's another one:


With the final equation being this:


The other equations on here work, but I like this one because it makes getting the row number easy, which I find I need to do more often. Just the row number would be like this:


I originally tried to find just this to solve a spreadsheet issue, but couldn't find anything useful that just gave the row number of the last entry, so hopefully this is helpful for someone.

Also, this has the added advantage that it works for any type of data in any order, and you can have blank rows in between rows with content, and it doesn't count cells with formulas that evaluate to "". It can also handle repeated values. All in all it's very similar to the equation that uses max((G:G<>"")*row(G:G)) on here, but makes pulling out the row number a little easier if that's what you're after.

Alternatively, if you want to put a script on your sheet you can make it easy on yourself if you plan on doing this a lot. Here's that scirpt:

function lastRow(sheet,column) {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  if (column == null) {
    if (sheet != null) {
       var sheet = ss.getSheetByName(sheet);
    } else {
      var sheet = ss.getActiveSheet();
    return sheet.getLastRow();
  } else {
    var sheet = ss.getSheetByName(sheet);
    var lastRow = sheet.getLastRow();
    var array = sheet.getRange(column + 1 + ':' + column + lastRow).getValues();
    for (i=0;i<array.length;i++) {
      if (array[i] != '') {       
        var final = i + 1;
    if (final != null) {
      return final;
    } else {
      return 0;

Here you can just type in the following if you want the last row on the same of the sheet that you're currently editing:


or if you want the last row of a particular column from that sheet, or of a particular column from another sheet you can do the following:


And for the last row of a particular sheet in general:


Then to get the actual data you can either use indirect:


or you can modify the above script at the last two return lines (the last two since you would have to put both the sheet and the column to get the actual value from an actual column), and replace the variable with the following:

return sheet.getRange(column + final).getValue();


return sheet.getRange(column + lastRow).getValue();

One benefit of this script is that you can choose if you want to include equations that evaluate to "". If no arguments are added equations evaluating to "" will be counted, but if you specify a sheet and column they will now be counted. Also, there's a lot of flexibility if you're willing to use variations of the script.

Probably overkill, but all possible.

Insert Picture into SQL Server 2005 Image Field using only SQL

For updating a record:

 UPDATE Employees SET [Photo] = (SELECT
 MyImage.* from Openrowset(Bulk
 'C:\photo.bmp', Single_Blob) MyImage)
 where Id = 10


  • Make sure to add the 'BULKADMIN' Role Permissions for the login you are using.
  • Paths are not pointing to your computer when using SQL Server Management Studio. If you start SSMS on your local machine and connect to a SQL Server instance on server X, the file C:\photo.bmp will point to hard drive C: on server X, not your machine!

How to Find App Pool Recycles in Event Log

It seemed quite hard to find this information, but eventually, I came across this question
You have to look at the 'System' event log, and filter by the WAS source.
Here is more info about the WAS (Windows Process Activation Service)

Succeeded installing but could not start apache 2.4 on my windows 7 system

This may be because of shortage in physical RAM.

Check minimum system requirements in the docs and try to close unnecessary programs if possible.

Characters allowed in GET parameter

From RFC 1738 on which characters are allowed in URLs:

Only alphanumerics, the special characters "$-_.+!*'(),", and reserved characters used for their reserved purposes may be used unencoded within a URL.

The reserved characters are ";", "/", "?", ":", "@", "=" and "&", which means you would need to URL encode them if you wish to use them.

How to write text in ipython notebook?

Change the cell type to Markdown in the menu bar, from Code to Markdown. Currently in Notebook 4.x, the keyboard shortcut for such an action is: Esc (for command mode), then m (for markdown).

using if else with eval in aspx page

<%# (string)Eval("gender") =="M" ? "Male" :"Female"%>

How to get just the parent directory name of a specific file

File file = new File("C:/aaa/bbb/ccc/ddd/");
File curentPath = new File(file.getParent());
//get current path "C:/aaa/bbb/ccc/ddd/"
String currentFolder= currentPath.getName().toString();
//get name of file to string "ddd"

if you need to append folder "ddd" by another path use;

String currentFolder= "/" + currentPath.getName().toString();

How to get the selected index of a RadioGroup in Android

You should be able to do something like this:

int radioButtonID = radioButtonGroup.getCheckedRadioButtonId();
View radioButton = radioButtonGroup.findViewById(radioButtonID);
int idx = radioButtonGroup.indexOfChild(radioButton);

If the RadioGroup contains other Views (like a TextView) then the indexOfChild() method will return wrong index.

To get the selected RadioButton text on the RadioGroup:

 RadioButton r = (RadioButton) radioButtonGroup.getChildAt(idx);
 String selectedtext = r.getText().toString();

Easy way to convert Iterable to Collection

With Guava you can use Lists.newArrayList(Iterable) or Sets.newHashSet(Iterable), among other similar methods. This will of course copy all the elements in to memory. If that isn't acceptable, I think your code that works with these ought to take Iterable rather than Collection. Guava also happens to provide convenient methods for doing things you can do on a Collection using an Iterable (such as Iterables.isEmpty(Iterable) or Iterables.contains(Iterable, Object)), but the performance implications are more obvious.