Programs & Examples On #Swfmill

How to check if a date is in a given range?

It's not necessary to convert to timestamp to do the comparison, given that the strings are validated as dates in 'YYYY-MM-DD' canonical format.

This test will work:

( ( $date_from_user >= $start_date ) && ( $date_from_user <= $end_date ) )


$start_date     = '2009-06-17';
$end_date       = '2009-09-05';
$date_from_user = '2009-08-28';

NOTE: Comparing strings like this does allow for "non-valid" dates e.g. (December 32nd ) '2009-13-32' and for weirdly formatted strings '2009/3/3', such that a string comparison will NOT be equivalent to a date or timestamp comparison. This works ONLY if the date values in the strings are in a CONSISTENT and CANONICAL format.

EDIT to add a note here, elaborating on the obvious.

By CONSISTENT, I mean for example that the strings being compared must be in identical format: the month must always be two characters, the day must always be two characters, and the separator character must always be a dash. We can't reliably compare "strings" that aren't four character year, two character month, two character day. If we had a mix of one character and two character months in the strings, for example, we'd get unexpected result when we compared, '2009-9-30' to '2009-10-11'. We humanly see "9" as being less than "10", but a string comparison will see '2009-9' as greater than '2009-1'. We don't necessarily need to have a dash separator characters; we could just as reliably compare strings in 'YYYYMMDD' format; if there is a separator character, it has to always be there and always be the same.

By CANONICAL, I mean that a format that will result in strings that will be sorted in date order. That is, the string will have a representation of "year" first, then "month", then "day". We can't reliably compare strings in 'MM-DD-YYYY' format, because that's not canonical. A string comparison would compare the MM (month) before it compared YYYY (year) since the string comparison works from left to right.) A big benefit of the 'YYYY-MM-DD' string format is that it is canonical; dates represented in this format can reliably be compared as strings.


If you do go for the php timestamp conversion, be aware of the limitations.

On some platforms, php does not support timestamp values earlier than 1970-01-01 and/or later than 2038-01-19. (That's the nature of the unix timestamp 32-bit integer.) Later versions pf php (5.3?) are supposed to address that.

The timezone can also be an issue, if you aren't careful to use the same timezone when converting from string to timestamp and from timestamp back to string.


Sort arrays of primitive types in descending order

Your algorithm is correct. But we can do optimization as follows: While reversing, You may try keeping another variable to reduce backward counter since computing of array.length-(i+1) may take time! And also move declaration of temp outside so that everytime it needs not to be allocated

double temp;

for(int i=0,j=array.length-1; i < (array.length/2); i++, j--) {

     // swap the elements
     temp = array[i];
     array[i] = array[j];
     array[j] = temp;

How to use Spring Boot with MySQL database and JPA?

For Jpa based application: base package scan @EnableJpaRepositories(basePackages = "repository") You can try it once!!!
Project Structure

 +- stack
     +- app
     |   +-
     +- controller
     |   +-
     +- service
     |   +-
     +- repository
     |   +-
     +- model
     |   +-
    mysql, lombok, data-jpa

#Data source :

#Jpa/Hibernate : = org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.ddl-auto = update

@Table (name = "employee")
public class Employee {

    @GeneratedValue (strategy = GenerationType.IDENTITY)
    private Long id;

    @Column (name = "first_name")
    private String firstName;
    @Column (name = "last_name")
    private String lastName;
    @Column (name = "email")
    private String email;
    @Column (name = "phone_number")
    private String phoneNumber;
    @Column (name = "emp_desg")
    private String desgination;

public interface EmployeeRepository extends JpaRepository<Employee, Long> {

public class EmployeeController {

    private EmployeeService empService;

    @GetMapping (value = "/employees")
    public List<Employee> getAllEmployee(){
        return empService.getAllEmployees();

    @PostMapping (value = "/employee")
    public ResponseEntity<Employee> addEmp(@RequestBody Employee emp, HttpServletRequest 
                                         request) throws URISyntaxException {
        HttpHeaders headers = new HttpHeaders();
        headers.setLocation(new URI(request.getRequestURI() + "/" + emp.getId()));
        return new ResponseEntity<Employee>(emp, headers, HttpStatus.CREATED);

public interface EmployeeService {
    public List<Employee> getAllEmployees();
    public Employee saveEmployee(Employee emp);

public class EmployeeServiceImpl implements EmployeeService {

    private EmployeeRepository empRepository;

    public List<Employee> getAllEmployees() {
        return empRepository.findAll();

    public Employee saveEmployee(Employee emp) {

@EnableJpaRepositories(basePackages = "repository")
public class EmployeeApplication {
    public static void main(String[] args) {, args);

Best timing method in C?

gettimeofday() will probably do what you want.

If you're on Intel hardware, here's how to read the CPU real-time instruction counter. It will tell you the number of CPU cycles executed since the processor was booted. This is probably the finest-grained, lowest overhead counter you can get for performance measurement.

Note that this is the number of CPU cycles. On linux you can get the CPU speed from /proc/cpuinfo and divide to get the number of seconds. Converting this to a double is quite handy.

When I run this on my box, I get

it took this long to call printf: 207485

Here's the Intel developer's guide that gives tons of detail.

#include <stdio.h>
#include <stdint.h>

inline uint64_t rdtsc() {
    uint32_t lo, hi;
    __asm__ __volatile__ (
      "xorl %%eax, %%eax\n"
      : "=a" (lo), "=d" (hi)
      : "%ebx", "%ecx");
    return (uint64_t)hi << 32 | lo;

    unsigned long long x;
    unsigned long long y;
    x = rdtsc();
    y = rdtsc();
    printf("it took this long to call printf: %lld\n",y-x);

VBA EXCEL To Prompt User Response to Select Folder and Return the Path as String Variable


Function GetFolder() As String
    Dim fldr As FileDialog
    Dim sItem As String
    Set fldr = Application.FileDialog(msoFileDialogFolderPicker)
    With fldr
        .Title = "Select a Folder"
        .AllowMultiSelect = False
        .InitialFileName = Application.DefaultFilePath
        If .Show <> -1 Then GoTo NextCode
        sItem = .SelectedItems(1)
    End With
    GetFolder = sItem
    Set fldr = Nothing
End Function

This code was adapted from Ozgrid

and as jkf points out, from Mr Excel

.htaccess not working on localhost with XAMPP

Edit the .htaccess file, so the first line reads 'Test.':


Set the default handler

DirectoryIndex index.php index.html index.htm


Using the last-child selector

If you think you can use Javascript, then since jQuery support last-child, you can use jQuery's css method and the good thing it will support almost all the browsers

Example Code:

   $("#nav li:last-child").css("border-bottom","1px solid #b5b5b5")

You can find more info about here :

Why rgb and not cmy?

This is nothing to do with hardware nor software. Simply that RGB are the 3 primary colours which can be combined in various ways to produce every other colour. It is more about the human convention/perception of colours which carried over.

You may find this article interesting.

What's a "static method" in C#?

Core of the static keyword that you will have only one copy at RAM of this (method /variable /class ) that's shared for all calling

"Could not find or load main class" Error while running java program using cmd prompt

Execute your Java program using java -d . HelloWorld command.

This command works when you have declared package.

. represent current directory/.

How to convert DATE to UNIX TIMESTAMP in shell script on MacOS

date +%s

This works fine for me on OS X Lion.

caching JavaScript files

From PHP:

function OutputJs($Content) 
    echo $Content;
    $expires = DAY_IN_S; // 60 * 60 * 24 ... defined elsewhere
    header("Content-type: x-javascript");
    header('Content-Length: ' . ob_get_length());
    header('Cache-Control: max-age='.$expires.', must-revalidate');
    header('Pragma: public');
    header('Expires: '. gmdate('D, d M Y H:i:s', time()+$expires).'GMT');

works for me.

As a developer you'll probably quickly run into the situation that you don't want files cached, in which case see Help with aggressive JavaScript caching

Find indices of elements equal to zero in a NumPy array

If you are working with a one-dimensional array there is a syntactic sugar:

>>> x = numpy.array([1,0,2,0,3,0,4,5,6,7,8])
>>> numpy.flatnonzero(x == 0)
array([1, 3, 5])

How do I pass a URL with multiple parameters into a URL?

In your example parts of your passed-in URL are not URL encoded (for example the colon should be %3A, the forward slashes should be %2F). It looks like you have encoded the parameters to your parameter URL, but not the parameter URL itself. Try encoding it as well. You can use encodeURIComponent.

How can I find script's directory?

import os
exec_filepath = os.path.realpath(__file__)
exec_dirpath = exec_filepath[0:len(exec_filepath)-len(os.path.basename(__file__))]

How can I "reset" an Arduino board?

Make sure you plug the Arduino directly into the computer and not through a hub. Using a hub will give you this error.

plot a circle with pyplot

If you aim to have the "circle" maintain a visual aspect ratio of 1 no matter what the data coordinates are, you could use the scatter() method.

import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [10, 20, 30, 40, 50]
r = [100, 80, 60, 40, 20] # in points, not data units
fig, ax = plt.subplots(1, 1)
ax.scatter(x, y, s=r)

Image is a scatter plot. Five circles along the line y=10x have decreasing radii from bottom left to top right. Although the graph is square-shaped, the y-axis has 10 times the range of the x-axis. Even so, the aspect ratio of the circles is 1 on the screen.

How to subtract X day from a Date object in Java?

@JigarJoshi it's the good answer, and of course also @Tim recommendation to use .joda-time.

I only want to add more possibilities to subtract days from a java.util.Date.


One possibility is to use apache-commons-lang. You can do it using DateUtils as follows:

Date dateBefore30Days = DateUtils.addDays(new Date(),-30);

Of course add the commons-lang dependency to do only date subtract it's probably not a good options, however if you're already using commons-lang it's a good choice. There is also convenient methods to addYears,addMonths,addWeeks and so on, take a look at the api here.

Java 8

Another possibility is to take advantage of new LocalDate from Java 8 using minusDays(long days) method:

LocalDate dateBefore30Days ="Europe/Paris")).minusDays(30);

Is it possible to capture a Ctrl+C signal and run a cleanup function, in a "defer" fashion?

There were (at time of posting) one or two little typos in the accepted answer above, so here's the cleaned up version. In this example I'm stopping the CPU profiler when receiving Ctrl+C.

// capture ctrl+c and stop CPU profiler                            
c := make(chan os.Signal, 1)                                       
signal.Notify(c, os.Interrupt)                                     
go func() {                                                        
  for sig := range c {                                             
    log.Printf("captured %v, stopping profiler and exiting..", sig)

How do I navigate to a parent route from a child route?

You can navigate to your parent root like this

this.router.navigate(['.'], { relativeTo: this.activeRoute.parent });

You will need to inject the current active Route in the constructor

    private router: Router,
    private activeRoute: ActivatedRoute) {


Remove Last Comma from a string

The greatly upvoted answer removes not only the final comma, but also any spaces that follow. But removing those following spaces was not what was part of the original problem. So:

let str = 'abc,def,ghi, ';
let str2 = str.replace(/,(?=\s*$)/, '');
alert("'" + str2 + "'");
'abc,def,ghi '

Renaming columns in Pandas


old_names = ['$a', '$b', '$c', '$d', '$e'] 
new_names = ['a', 'b', 'c', 'd', 'e']
df.rename(columns=dict(zip(old_names, new_names)), inplace=True)

This way you can manually edit the new_names as you wish. It works great when you need to rename only a few columns to correct misspellings, accents, remove special characters, etc.

Android Studio was unable to find a valid Jvm (Related to MAC OS)

Java was uninstalled when I updated to OS X El Capitan.

See screenshot of terminal before and after I reinstalled Java.

enter image description here

To reinstall Java I followed this link that was provided in the Android Studio dialog box.

enter image description here

Android Studio ran again after the Java installation was reinstalled.

Real-world examples of recursion

Famous Eval/Apply cycle from SICP

alt text

Here is the definition of eval:

(define (eval exp env)
  (cond ((self-evaluating? exp) exp)
        ((variable? exp) (lookup-variable-value exp env))
        ((quoted? exp) (text-of-quotation exp))
        ((assignment? exp) (eval-assignment exp env))
        ((definition? exp) (eval-definition exp env))
        ((if? exp) (eval-if exp env))
        ((lambda? exp)
         (make-procedure (lambda-parameters exp)
                         (lambda-body exp)
        ((begin? exp) 
         (eval-sequence (begin-actions exp) env))
        ((cond? exp) (eval (cond->if exp) env))
        ((application? exp)
         (apply (eval (operator exp) env)
                (list-of-values (operands exp) env)))
         (error "Unknown expression type - EVAL" exp))))

Here is the definition of apply:

(define (apply procedure arguments)
  (cond ((primitive-procedure? procedure)
         (apply-primitive-procedure procedure arguments))
        ((compound-procedure? procedure)
           (procedure-body procedure)
             (procedure-parameters procedure)
             (procedure-environment procedure))))
          "Unknown procedure type - APPLY" procedure))))

Here is the definition of eval-sequence:

(define (eval-sequence exps env)
  (cond ((last-exp? exps) (eval (first-exp exps) env))
        (else (eval (first-exp exps) env)
              (eval-sequence (rest-exps exps) env))))

eval -> apply -> eval-sequence -> eval

Where do I find the definition of size_t?

size_t should be defined in your standard library's headers. In my experience, it usually is simply a typedef to unsigned int. The point, though, is that it doesn't have to be. Types like size_t allow the standard library vendor the freedom to change its underlying data types if appropriate for the platform. If you assume size_t is always unsigned int (via casting, etc), you could run into problems in the future if your vendor changes size_t to be e.g. a 64-bit type. It is dangerous to assume anything about this or any other library type for this reason.

Force page scroll position to top at page refresh in HTML

This is one of the best way to do so:

$(window).on('beforeunload', function() {

How to split a string into a list?

Splits the string in text on any consecutive runs of whitespace.

words = text.split()      

Split the string in text on delimiter: ",".

words = text.split(",")   

The words variable will be a list and contain the words from text split on the delimiter.

What is the non-jQuery equivalent of '$(document).ready()'?

Now that it's 2018 here's a quick and simple method.

This will add an event listener, but if it already fired we'll check that the dom is in a ready state or that it's complete. This can fire before or after sub-resources have finished loading (images, stylesheets, frames, etc).

function domReady(fn) {_x000D_
  // If we're early to the party_x000D_
  document.addEventListener("DOMContentLoaded", fn);_x000D_
  // If late; I mean on time._x000D_
  if (document.readyState === "interactive" || document.readyState === "complete" ) {_x000D_
domReady(() => console.log("DOM is ready, come and get it!"));

Additional Readings


Here's some quick utility helpers using standard ES6 Import & Export I wrote that include TypeScript as well. Maybe I can get around to making these a quick library that can be installed into projects as a dependency.


export const domReady = (callBack) => {
  if (document.readyState === "loading") {
    document.addEventListener('DOMContentLoaded', callBack);
  else {

export const windowReady = (callBack) => {
  if (document.readyState === 'complete') {
  else {
    window.addEventListener('load', callBack);


export const domReady = (callBack: () => void) => {
  if (document.readyState === "loading") {
    document.addEventListener('DOMContentLoaded', callBack);
  else {

export const windowReady = (callBack: () => void) => {
  if (document.readyState === 'complete') {
  else {
    window.addEventListener('load', callBack);


export const domReady = new Promise(resolve => {
  if (document.readyState === "loading") {
    document.addEventListener('DOMContentLoaded', resolve);
  else {

export const windowReady = new Promise(resolve => {
  if (document.readyState === 'complete') {
  else {
    window.addEventListener('load', resolve);

Generating all permutations of a given string

python implementation

def getPermutation(s, prefix=''):
        if len(s) == 0:
                print prefix
        for i in range(len(s)):
                getPermutation(s[0:i]+s[i+1:len(s)],prefix+s[i] )


How to parse XML in Bash?

Another command line tool is my new Xidel. It also supports XPath 2 and XQuery, contrary to the already mentioned xpath/xmlstarlet.

The title can be read like:

xidel xhtmlfile.xhtml -e /html/head/title > titleOfXHTMLPage.txt

And it also has a cool feature to export multiple variables to bash. For example

eval $(xidel xhtmlfile.xhtml -e 'title := //title, imgcount := count(//img)' --output-format bash )

sets $title to the title and $imgcount to the number of images in the file, which should be as flexible as parsing it directly in bash.

How To Set A JS object property name from a variable

Use a variable as an object key

let key = 'myKey';

let data = {[key] : 'name1'; }

See How to iterete on your object here

Can I pass a JavaScript variable to another browser window?

I have struggled to successfully pass arguments to the newly opened window.
Here is what I came up with :

function openWindow(path, callback /* , arg1 , arg2, ... */){
    var args =, 2); // retrieve the arguments
    var w =; // open the new window
    w.addEventListener('load', afterLoadWindow.bind(w, args), false); // listen to the new window's load event
    function afterLoadWindow(/* [arg1,arg2,...], loadEvent */){
        callback.apply(this, arguments[0]); // execute the callbacks, passing the initial arguments (arguments[1] contains the load event)

Example call:

openWindow("/contact",function(firstname, lastname){
    this.alert("Hello "+firstname+" "+lastname);
}, "John", "Doe");

Live example

C char* to int conversion

Use atoi() from <stdlib.h>

Or, write your own atoi() function which will convert char* to int

int a2i(const char *s)
  int sign=1;
  if(*s == '-'){
    sign = -1;
  int num=0;
  return num*sign;

Error message 'Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.'

I had the same error message reported when compiling a Visual Studio package (VSPackage). The whole solution compiles and the error is thrown when the package is being created by CreatePkgDef. Having said that, it is clear that I cannot catch the LoaderExceptions as it is not my application that throws it, but Microsoft's own tool. (Though I am responsible for the confusion of CreatePkgDef.)

In my case the root cause was that my solution creates a MyDll.dll that has already been registered to the GAC (and they are different), so the CreatePgkDef got confused which one to use and it decided just to throw an error which isn't really helpful. The MyDll.dll in the GAC was registered by the installer of the same product (obviously an earlier version, with /slightly/ different content).

How to fix it

  1. Preferred way: Make sure you use the correct version of MyDll.dll
    1. When compiling your project make sure you use a different version number than you used in the previous version located in the GAC. Make sure the following attributes are correct:
      • [assembly: AssemblyVersion("")] // Assuming the old DLL file was versioned
      • [assembly: AssemblyFileVersion("")] // Assuming the old DLL file was versioned
    2. If needed, specify the fully qualified assembly name (for example, "MyDll.dll, Version=, Culture=neutral, PublicKeyToken=1234567890abcdef") when you reference it in your other projects.
  2. If the above failed: You can uninstall the old MyDll.dll from GAC
    1. How to Uninstall an Assembly from the GAC
    2. Uninstall the application that includes MyDll.dll

Changing the AssemblyVersion was good enough for me. :)

I hope this was helpful.

How to upload file to server with HTTP POST multipart/form-data?

Top to @loop answer.

We got below error for Asp.Net MVC, Unable to connect to the remote server

Fix: After adding the below code in Web.Confing issue has been resolved for us

    <defaultProxy useDefaultCredentials="true" >

What is the meaning of single and double underscore before an object name?

Since so many people are referring to Raymond's talk, I'll just make it a little easier by writing down what he said:

The intention of the double underscores was not about privacy. The intention was to use it exactly like this

class Circle(object):

    def __init__(self, radius):
        self.radius = radius

    def area(self):
        p = self.__perimeter()
        r = p / math.pi / 2.0
        return math.pi * r ** 2.0

    def perimeter(self):
        return 2.0 * math.pi * self.radius

    __perimeter = perimeter  # local reference

class Tire(Circle):

    def perimeter(self):
        return Circle.perimeter(self) * 1.25

It's actually the opposite of privacy, it's all about freedom. It makes your subclasses free to override any one method without breaking the others.

Say you don't keep a local reference of perimeter in Circle. Now, a derived class Tire overrides the implementation of perimeter, without touching area. When you call Tire(5).area(), in theory it should still be using Circle.perimeter for computation, but in reality it's using Tire.perimeter, which is not the intended behavior. That's why we need a local reference in Circle.

But why __perimeter instead of _perimeter? Because _perimeter still gives derived class the chance to override:

class Tire(Circle):

    def perimeter(self):
        return Circle.perimeter(self) * 1.25

    _perimeter = perimeter

Double underscores has name mangling, so there's a very little chance that the local reference in parent class get override in derived class. thus "makes your subclasses free to override any one method without breaking the others".

If your class won't be inherited, or method overriding does not break anything, then you simply don't need __double_leading_underscore.

Undo working copy modifications of one file in Git?

I always get confused with this, so here is a reminder test case; let's say we have this bash script to test git:

set -x
rm -rf test
mkdir test
cd test
git init
git config test
git config [email protected]
echo 1 > a.txt
echo 1 > b.txt
git add *
git commit -m "initial commit"
echo 2 >> b.txt
git add b.txt
git commit -m "second commit"
echo 3 >> b.txt

At this point, the change is not staged in the cache, so git status is:

$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   b.txt

no changes added to commit (use "git add" and/or "git commit -a")

If from this point, we do git checkout, the result is this:

$ git checkout HEAD -- b.txt
$ git status
On branch master
nothing to commit, working directory clean

If instead we do git reset, the result is:

$ git reset HEAD -- b.txt
Unstaged changes after reset:
M   b.txt
$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   b.txt

no changes added to commit (use "git add" and/or "git commit -a")

So, in this case - if the changes are not staged, git reset makes no difference, while git checkout overwrites the changes.

Now, let's say that the last change from the script above is staged/cached, that is to say we also did git add b.txt at the end.

In this case, git status at this point is:

$ git status
On branch master
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    modified:   b.txt

If from this point, we do git checkout, the result is this:

$ git checkout HEAD -- b.txt
$ git status
On branch master
nothing to commit, working directory clean

If instead we do git reset, the result is:

$ git reset HEAD -- b.txt
Unstaged changes after reset:
M   b.txt
$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   b.txt

no changes added to commit (use "git add" and/or "git commit -a")

So, in this case - if the changes are staged, git reset will basically make staged changes into unstaged changes - while git checkout will overwrite the changes completely.

Losing Session State

Your session is lost becoz....

I have found a scenario where session is lost - In a page, for a amount text box field has invalid characters, and followed by a session variable retrieval for other purpose.After posting the invalid number parsing through Convert.ToInt32 or double raises a first chance exception, but error does not show at that line, Instead of that, Session being null because of unhandled exception, shows error at session retrieval, thus deceiving the debugging...

HINT: Test your system to fail it- DESTRUCTIVE.. enter enough junk in unrelated scenarios for ex: after search results shown enter junk in search criteria and goto details of search result... , you would be able to reproduce this machine on your local code base too...:)

Hope it Helps, hydtechie

Escaping double quotes in JavaScript onClick event handler

Did you try

&quot; or \x22

instead of



Call a React component method from outside

You can do like

import React from 'react';

class Header extends React.Component{

        window.helloComponent = this;

       console.log("Called from outside");


      return (
      <AppBar style={{background:'#000'}}>

export default Header;

Now from outside of this component you can called like this below


Rotating a view in Android

You could create an animation and apply it to your button view. For example:

    // Locate view
    ImageView diskView = (ImageView) findViewById(;

    // Create an animation instance
    Animation an = new RotateAnimation(0.0f, 360.0f, pivotX, pivotY);

    // Set the animation's parameters
    an.setDuration(10000);               // duration in ms
    an.setRepeatCount(0);                // -1 = infinite repeated
    an.setRepeatMode(Animation.REVERSE); // reverses each repeat
    an.setFillAfter(true);               // keep rotation after animation

    // Aply animation to image view

Cannot convert lambda expression to type 'string' because it is not a delegate type

I think you are missing using System.Linq; from this system class.

and also add using System.Data.Entity; to the code

How to convert numpy arrays to standard TensorFlow format?

You can use placeholders and feed_dict.

Suppose we have numpy arrays like these:

trX = np.linspace(-1, 1, 101) 
trY = 2 * trX + np.random.randn(*trX.shape) * 0.33 

You can declare two placeholders:

X = tf.placeholder("float") 
Y = tf.placeholder("float")

Then, use these placeholders (X, and Y) in your model, cost, etc.: model = tf.mul(X, w) ... Y ... ...

Finally, when you run the model/cost, feed the numpy arrays using feed_dict:

with tf.Session() as sess:
...., feed_dict={X: trY, Y: trY})

Execute a SQL Stored Procedure and process the results


To execute a stored procedure returning rows programmatically using a command object

Dim sqlConnection1 As New SqlConnection("Your Connection String")
Dim cmd As New SqlCommand
Dim reader As SqlDataReader

cmd.CommandText = "StoredProcedureName"
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = sqlConnection1


reader = cmd.ExecuteReader()
' Data is accessible through the DataReader object here.
' Use Read method (true/false) to see if reader has records and advance to next record
' You can use a While loop for multiple records (While reader.Read() ... End While)
If reader.Read() Then
  someVar = reader(0)
  someVar2 = reader(1)
  someVar3 = reader("NamedField")
End If    


Why does modulus division (%) only work with integers?

The modulo operator % in C and C++ is defined for two integers, however, there is an fmod() function available for usage with doubles.

encapsulation vs abstraction real world example

Encapsulation helps in adhering to Single Responsibility principle and Abstraction helps in adhering to Code to Interface and not to implement.

Say I have a class for Car : Service Provider Class and Driver Class : Service Consumer Class.

For Abstraction : we define abstract Class for CAR and define all the abstract methods in it , which are function available in the car like : changeGear(), applyBrake().

Now the actual Car (Concrete Class i.e. like Mercedes , BMW will implement these methods in their own way and abstract the execution and end user will still apply break and change gear for particular concrete car instance and polymorphically the execution will happen as defined in concrete class.

For Encapsulation : Now say Mercedes come up with new feature/technology: Anti Skid Braking, while implementing the applyBrake(), it will encapsulate this feature in applyBrake() method and thus providing cohesion, and service consumer will still access by same method applyBrake() of the car object. Thus Encapsulation lets further in same concrete class implementation.

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at

The use-case for CORS is simple. Imagine the site has some data that the site wants to access. This type of request traditionally wouldn’t be allowed under the browser’s same origin policy. However, by supporting CORS requests, can add a few special response headers that allows to access the data. In order to understand it well, please visit this nice tutorial.. How to solve the issue of CORS

What is the best way to compare 2 folder trees on windows?

As I am reluctant to install new programs into my machine, this PowerShell script (from Hey, Scripting Guy! Blog) helped me solve my problem. I only modified the path to suit my case:

$fso = Get-ChildItem -Recurse -path F:\songs
$fsoBU = Get-ChildItem -Recurse -path D:\songs
Compare-Object -ReferenceObject $fso -DifferenceObject $fsoBU

How to access the elements of a 2D array?

If you want do many calculation with 2d array, you should use NumPy array instead of nest list.

for your question, you can use:zip(*a) to transpose it:

In [55]: a=[[1,1],[2,1],[3,1]]
In [56]: zip(*a)
Out[56]: [(1, 2, 3), (1, 1, 1)]
In [57]: zip(*a)[0]
Out[57]: (1, 2, 3)

C# version of java's synchronized keyword?

Does c# have its own version of the java "synchronized" keyword?

No. In C#, you explicitly lock resources that you want to work on synchronously across asynchronous threads. lock opens a block; it doesn't work on method level.

However, the underlying mechanism is similar since lock works by invoking Monitor.Enter (and subsequently Monitor.Exit) on the runtime. Java works the same way, according to the Sun documentation.

How to Get JSON Array Within JSON Object?

JSONObject jsonObj = new JSONObject(jsonString);

JSONArray jArray = jsonObj.getJSONArray("data");
int length = jArray.length();

   for(int i=0; i<length; i++)
        JSONObject jObj = jArray.getJSONObject(i);
        String id = jObj.optString("id");
        String name=jObj.optString("name");

        JSONArray ingredientArray = jObj.getJSONArray("Ingredients");
        int size = ingredientArray.length();
        ArrayList<String> Ingredients = new ArrayList<>();

            for(int j=0; j<size; j++)
                    JSONObject json = ja.getJSONObject(j);


SQL WHERE.. IN clause multiple columns

Simple and wrong way would be combine two columns using + or concatenate and make one columns.

Select *
from XX
where col1+col2 in (Select col1+col2 from YY)

This would be offcourse pretty slow. Can not be used in programming but if in case you are just querying for verifying something may be used.

Simple linked list in C++

Here is my implementation.

#include <iostream>

using namespace std;

template< class T>
struct node{
    T m_data;
    node* m_next_node;

    node(T t_data, node* t_node) :
        m_data(t_data), m_next_node(t_node){}

        std::cout << "Address :" << this << " Destroyed" << std::endl;

template<class T>
class linked_list {
    node<T>* m_list;

    linked_list(): m_list(nullptr){}

    void add_node(T t_data) {
        node<T>* _new_node = new node<T>(t_data, nullptr);
        _new_node->m_next_node = m_list;
        m_list = _new_node;

    void populate_nodes(node<T>* t_node) {
        if  (t_node != nullptr) {
            std::cout << "Data =" << t_node->m_data
                      << ", Address =" << t_node->m_next_node
                      << std::endl;

    void delete_nodes(node<T>* t_node) {
        if (t_node != nullptr) {


int main()
    linked_list<float>* _ll = new linked_list<float>();





    return 0;

enter image description here

How to download a file over HTTP?

You can use PycURL on Python 2 and 3.

import pycurl

FILE_DEST = 'pycurl.html'

with open(FILE_DEST, 'wb') as f:
    c = pycurl.Curl()
    c.setopt(c.URL, FILE_SRC)
    c.setopt(c.WRITEDATA, f)

What does getActivity() mean?

I to had a similar doubt what I got to know was getActivity() returns the Activity to which the fragment is associated.

The getActivity() method is used generally in static fragment as the associated activity will not be static and non static member cannot be used in static member.

I used <code>getActivity()</code> here to get non-static activity to which the the placeholder fragment is associated.

How to merge lists into a list of tuples?

In Python 2:

>>> list_a = [1, 2, 3, 4]
>>> list_b = [5, 6, 7, 8]
>>> zip(list_a, list_b)
[(1, 5), (2, 6), (3, 7), (4, 8)]

In Python 3:

>>> list_a = [1, 2, 3, 4]
>>> list_b = [5, 6, 7, 8]
>>> list(zip(list_a, list_b))
[(1, 5), (2, 6), (3, 7), (4, 8)]

'nuget' is not recognized but other nuget commands working

There are much nicer ways to do it.

  1. Install Nuget.Build package in you project that you want to pack. May need to close and re-open solution after install.
  2. Install nuget via chocolatey - much nicer. Install chocolatey:, then run

    cinst Nuget.CommandLine

in your command prompt. This will install nuget and setup environment paths, so nuget is always available.

In Angular, What is 'pathmatch: full' and what effect does it have?

The path-matching strategy, one of 'prefix' or 'full'. Default is 'prefix'.

By default, the router checks URL elements from the left to see if the URL matches a given path, and stops when there is a match. For example, '/team/11/user' matches 'team/:id'.

The path-match strategy 'full' matches against the entire URL. It is important to do this when redirecting empty-path routes. Otherwise, because an empty path is a prefix of any URL, the router would apply the redirect even when navigating to the redirect destination, creating an endless loop.

Source :

What is a lambda expression in C++11?

The problem

C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function.

#include <algorithm>
#include <vector>

namespace {
  struct f {
    void operator()(int) {
      // do something

void func(std::vector<int>& v) {
  f f;
  std::for_each(v.begin(), v.end(), f);

If you only use f once and in that specific place it seems overkill to be writing a whole class just to do something trivial and one off.

In C++03 you might be tempted to write something like the following, to keep the functor local:

void func2(std::vector<int>& v) {
  struct {
    void operator()(int) {
       // do something
  } f;
  std::for_each(v.begin(), v.end(), f);

however this is not allowed, f cannot be passed to a template function in C++03.

The new solution

C++11 introduces lambdas allow you to write an inline, anonymous functor to replace the struct f. For small simple examples this can be cleaner to read (it keeps everything in one place) and potentially simpler to maintain, for example in the simplest form:

void func3(std::vector<int>& v) {
  std::for_each(v.begin(), v.end(), [](int) { /* do something here*/ });

Lambda functions are just syntactic sugar for anonymous functors.

Return types

In simple cases the return type of the lambda is deduced for you, e.g.:

void func4(std::vector<double>& v) {
  std::transform(v.begin(), v.end(), v.begin(),
                 [](double d) { return d < 0.00001 ? 0 : d; }

however when you start to write more complex lambdas you will quickly encounter cases where the return type cannot be deduced by the compiler, e.g.:

void func4(std::vector<double>& v) {
    std::transform(v.begin(), v.end(), v.begin(),
        [](double d) {
            if (d < 0.0001) {
                return 0;
            } else {
                return d;

To resolve this you are allowed to explicitly specify a return type for a lambda function, using -> T:

void func4(std::vector<double>& v) {
    std::transform(v.begin(), v.end(), v.begin(),
        [](double d) -> double {
            if (d < 0.0001) {
                return 0;
            } else {
                return d;

"Capturing" variables

So far we've not used anything other than what was passed to the lambda within it, but we can also use other variables, within the lambda. If you want to access other variables you can use the capture clause (the [] of the expression), which has so far been unused in these examples, e.g.:

void func5(std::vector<double>& v, const double& epsilon) {
    std::transform(v.begin(), v.end(), v.begin(),
        [epsilon](double d) -> double {
            if (d < epsilon) {
                return 0;
            } else {
                return d;

You can capture by both reference and value, which you can specify using & and = respectively:

  • [&epsilon] capture by reference
  • [&] captures all variables used in the lambda by reference
  • [=] captures all variables used in the lambda by value
  • [&, epsilon] captures variables like with [&], but epsilon by value
  • [=, &epsilon] captures variables like with [=], but epsilon by reference

The generated operator() is const by default, with the implication that captures will be const when you access them by default. This has the effect that each call with the same input would produce the same result, however you can mark the lambda as mutable to request that the operator() that is produced is not const.

Identify if a string is a number

If you want to check if a string is a number (I'm assuming it's a string since if it's a number, duh, you know it's one).

  • Without regex and
  • using Microsoft's code as much as possible

you could also do:

public static bool IsNumber(this string aNumber)
     BigInteger temp_big_int;
     var is_number = BigInteger.TryParse(aNumber, out temp_big_int);
     return is_number;

This will take care of the usual nasties:

  • Minus (-) or Plus (+) in the beginning
  • contains decimal character BigIntegers won't parse numbers with decimal points. (So: BigInteger.Parse("3.3") will throw an exception, and TryParse for the same will return false)
  • no funny non-digits
  • covers cases where the number is bigger than the usual use of Double.TryParse

You'll have to add a reference to System.Numerics and have using System.Numerics; on top of your class (well, the second is a bonus I guess :)

Revert a jQuery draggable object back to its original container on out event of droppable

It's related about revert origin : to set origin when the object is drag : just use $(this).data("draggable").originalPosition = {top:0, left:0};

For example : i use like this

               drag: function() {
                    var t = $(this);
                    left = parseInt(t.css("left")) * -1;
                    if(left > 0 ){
                        left = 0;
                        t.draggable( "option", "revert", true );
                        $(this).data("draggable").originalPosition = {top:0, left:0};
                    else t.draggable( "option", "revert", false );

                    $(".slider-work").css("left",  left);

Make A List Item Clickable (HTML/CSS)

Ditch the <a href="...">. Put the onclick (all lowercase) handler on the <li> tag itself.

Bootstrap - Uncaught TypeError: Cannot read property 'fn' of undefined

Import jquery first before bootstrap:

<script src="js/jquery.min.js"></script>
<script src="js/bootstrap.js"></script>
<script src="js/bootstrap.bundle.js"></script>

Does adding a duplicate value to a HashSet/HashMap replace the previous value

The docs are pretty clear on this: HashSet.add doesn't replace:

Adds the specified element to this set if it is not already present. More formally, adds the specified element e to this set if this set contains no element e2 such that (e==null ? e2==null : e.equals(e2)). If this set already contains the element, the call leaves the set unchanged and returns false.

But HashMap.put will replace:

If the map previously contained a mapping for the key, the old value is replaced.

Java Process with Input/Output Stream

You have writer.close(); in your code. So bash receives EOF on its stdin and exits. Then you get Broken pipe when trying to read from the stdoutof the defunct bash.

Limit on the WHERE col IN (...) condition

There is a limit, but you can split your values into separate blocks of in()

Select * 
From table 
Where Col IN (123,123,222,....)
or Col IN (456,878,888,....)

CSS display:inline property with list-style-image: property on <li> tags

I had similar problem, i solve using css ":before".. the code looks likes this:

.widgets li:before{
    content:"• ";

What use is find_package() if you need to specify CMAKE_MODULE_PATH anyway?

You don't need to specify the module path per se. CMake ships with its own set of built-in find_package scripts, and their location is in the default CMAKE_MODULE_PATH.

The more normal use case for dependent projects that have been CMakeified would be to use CMake's external_project command and then include the Use[Project].cmake file from the subproject. If you just need the Find[Project].cmake script, copy it out of the subproject and into your own project's source code, and then you won't need to augment the CMAKE_MODULE_PATH in order to find the subproject at the system level.

Android Studio Gradle DSL method not found: 'android()' -- Error(17,0)

I went ahead and downloaded the project from the link you provided:

Since this is an old tutorial, you simply need to upgrade the software, gradle, the android build tools and plugin.

Make sure you have the latest Gradle and Android Studio:


buildscript {
    repositories {

    dependencies {
        classpath ''

allprojects {
    repositories {


apply plugin: ''

android {
    compileSdkVersion 23
    buildToolsVersion '23.0.3'

    defaultConfig {
        minSdkVersion 9
        targetSdkVersion 23
        versionCode 1
        versionName '1.0'

dependencies {
    compile ''

Then run gradle:

gradle installDebug

Remove the legend on a matplotlib figure

I made a legend by adding it to the figure, not to an axis (matplotlib 2.2.2). To remove it, I set the legends attribute of the figure to an empty list:

import matplotlib.pyplot as plt

fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twinx()

ax1.plot(range(10), range(10, 20), label='line 1')
ax2.plot(range(10), range(30, 20, -1), label='line 2')


fig.legends = []

Where is the Postgresql config file: 'postgresql.conf' on Windows?

On my machine:

C:\Program Files\PostgreSQL\8.4\data\postgresql.conf

Detect if the device is iPhone X

I am trying to make work the previous replies and none of them worked for me. So I found one solution for SwiftUI. Creating a file called UIDevice+Notch.swift

And its content:

extension UIDevice {
    var hasNotch: Bool {
        let bottom = UIApplication.shared.keyWindow?.safeAreaInsets.bottom ?? 0
        return bottom > 0


if UIDevice.current.hasNotch {
    //... consider notch 
} else {
    //... don't have to consider notch 

Return HTML from ASP.NET Web API

ASP.NET Core. Approach 1

If your Controller extends ControllerBase or Controller you can use Content(...) method:

public ContentResult Index() 
    return base.Content("<div>Hello</div>", "text/html");

ASP.NET Core. Approach 2

If you choose not to extend from Controller classes, you can create new ContentResult:

public ContentResult Index() 
    return new ContentResult 
        ContentType = "text/html",
        Content = "<div>Hello World</div>"


Return string content with media type text/html:

public HttpResponseMessage Get()
    var response = new HttpResponseMessage();
    response.Content = new StringContent("<div>Hello World</div>");
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("text/html");
    return response;

How can I copy the output of a command directly into my clipboard?

I've created a tool for Linux/OSX/Cygwin that is similar to some of these others but slightly unique. I call it cb and it can be found in this github gist.

In that gist I demonstrate how to do copy and paste via commandline using Linux, macOS, and Cygwin.


    cat | xclip -selection clipboard

    xclip -selection clipboard -o


    cat | pbcopy



    cat > /dev/clipboard

    cat /dev/clipboard

Note: I originally just intended to mention this in my comment to Bob Enohp's answer. But then I realized that I should add a README to my gist. Since the gist editor doesn't offer a Markdown preview I used the answer box here and after copy/pasting it to my gist thought, "I might as well submit the answer."


A leak-proof tee to the clipboard

This script is modeled after tee (see man tee).

It's like your normal copy and paste commands, but unified and able to sense when you want it to be chainable



$ date | cb
# clipboard contains: Tue Jan 24 23:00:00 EST 2017


# clipboard retained from the previous block
$ cb
Tue Jan 24 23:00:00 EST 2017
$ cb | cat
Tue Jan 24 23:00:00 EST 2017
$ cb > foo
$ cat foo
Tue Jan 24 23:00:00 EST 2017


$ date | cb | tee updates.log
Tue Jan 24 23:11:11 EST 2017
$ cat updates.log
Tue Jan 24 23:11:11 EST 2017
# clipboard contains: Tue Jan 24 23:11:11 EST 2017

Copy via file redirect

(chronologically it made sense to demo this at the end)

# clipboard retained from the previous block
$ cb < foo
$ cb
Tue Jan 24 23:00:00 EST 2017
# note the minutes and seconds changed from 11 back to 00

How to unescape a Java string literal in Java?

The Problem

The org.apache.commons.lang.StringEscapeUtils.unescapeJava() given here as another answer is really very little help at all.

  • It forgets about \0 for null.
  • It doesn’t handle octal at all.
  • It can’t handle the sorts of escapes admitted by the java.util.regex.Pattern.compile() and everything that uses it, including \a, \e, and especially \cX.
  • It has no support for logical Unicode code points by number, only for UTF-16.
  • This looks like UCS-2 code, not UTF-16 code: they use the depreciated charAt interface instead of the codePoint interface, thus promulgating the delusion that a Java char is guaranteed to hold a Unicode character. It’s not. They only get away with this because no UTF-16 surrogate will wind up looking for anything they’re looking for.

The Solution

I wrote a string unescaper which solves the OP’s question without all the irritations of the Apache code.

 * unescape_perl_string()
 *      Tom Christiansen <[email protected]>
 *      Sun Nov 28 12:55:24 MST 2010
 * It's completely ridiculous that there's no standard
 * unescape_java_string function.  Since I have to do the
 * damn thing myself, I might as well make it halfway useful
 * by supporting things Java was too stupid to consider in
 * strings:
 *   => "?" items  are additions to Java string escapes
 *                 but normal in Java regexes
 *   => "!" items  are also additions to Java regex escapes
 * Standard singletons: ?\a ?\e \f \n \r \t
 *      NB: \b is unsupported as backspace so it can pass-through
 *          to the regex translator untouched; I refuse to make anyone
 *          doublebackslash it as doublebackslashing is a Java idiocy
 *          I desperately wish would die out.  There are plenty of
 *          other ways to write it:
 *              \cH, \12, \012, \x08 \x{8}, \u0008, \U00000008
 * Octal escapes: \0 \0N \0NN \N \NN \NNN
 *    Can range up to !\777 not \377
 *      TODO: add !\o{NNNNN}
 *          last Unicode is 4177777
 *          maxint is 37777777777
 * Control chars: ?\cX
 *      Means: ord(X) ^ ord('@')
 * Old hex escapes: \xXX
 *      unbraced must be 2 xdigits
 * Perl hex escapes: !\x{XXX} braced may be 1-8 xdigits
 *       NB: proper Unicode never needs more than 6, as highest
 *           valid codepoint is 0x10FFFF, not maxint 0xFFFFFFFF
 * Lame Java escape: \[IDIOT JAVA PREPROCESSOR]uXXXX must be
 *                   exactly 4 xdigits;
 *       I can't write XXXX in this comment where it belongs
 *       because the damned Java Preprocessor can't mind its
 *       own business.  Idiots!
 * Lame Python escape: !\UXXXXXXXX must be exactly 8 xdigits
 * TODO: Perl translation escapes: \Q \U \L \E \[IDIOT JAVA PREPROCESSOR]u \l
 *       These are not so important to cover if you're passing the
 *       result to Pattern.compile(), since it handles them for you
 *       further downstream.  Hm, what about \[IDIOT JAVA PREPROCESSOR]u?

public final static
String unescape_perl_string(String oldstr) {

     * In contrast to fixing Java's broken regex charclasses,
     * this one need be no bigger, as unescaping shrinks the string
     * here, where in the other one, it grows it.

    StringBuffer newstr = new StringBuffer(oldstr.length());

    boolean saw_backslash = false;

    for (int i = 0; i < oldstr.length(); i++) {
        int cp = oldstr.codePointAt(i);
        if (oldstr.codePointAt(i) > Character.MAX_VALUE) {
            i++; /****WE HATES UTF-16! WE HATES IT FOREVERSES!!!****/

        if (!saw_backslash) {
            if (cp == '\\') {
                saw_backslash = true;
            } else {
            continue; /* switch */

        if (cp == '\\') {
            saw_backslash = false;
            continue; /* switch */

        switch (cp) {

            case 'r':  newstr.append('\r');
                       break; /* switch */

            case 'n':  newstr.append('\n');
                       break; /* switch */

            case 'f':  newstr.append('\f');
                       break; /* switch */

            /* PASS a \b THROUGH!! */
            case 'b':  newstr.append("\\b");
                       break; /* switch */

            case 't':  newstr.append('\t');
                       break; /* switch */

            case 'a':  newstr.append('\007');
                       break; /* switch */

            case 'e':  newstr.append('\033');
                       break; /* switch */

             * A "control" character is what you get when you xor its
             * codepoint with '@'==64.  This only makes sense for ASCII,
             * and may not yield a "control" character after all.
             * Strange but true: "\c{" is ";", "\c}" is "=", etc.
            case 'c':   {
                if (++i == oldstr.length()) { die("trailing \\c"); }
                cp = oldstr.codePointAt(i);
                 * don't need to grok surrogates, as next line blows them up
                if (cp > 0x7f) { die("expected ASCII after \\c"); }
                newstr.append(Character.toChars(cp ^ 64));
                break; /* switch */

            case '8':
            case '9': die("illegal octal digit");
                      /* NOTREACHED */

     * may be 0 to 2 octal digits following this one
     * so back up one for fallthrough to next case;
     * unread this digit and fall through to next case.
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7': --i;
                      /* FALLTHROUGH */

             * Can have 0, 1, or 2 octal digits following a 0
             * this permits larger values than octal 377, up to
             * octal 777.
            case '0': {
                if (i+1 == oldstr.length()) {
                    /* found \0 at end of string */
                    break; /* switch */
                int digits = 0;
                int j;
                for (j = 0; j <= 2; j++) {
                    if (i+j == oldstr.length()) {
                        break; /* for */
                    /* safe because will unread surrogate */
                    int ch = oldstr.charAt(i+j);
                    if (ch < '0' || ch > '7') {
                        break; /* for */
                if (digits == 0) {
                    break; /* switch */
                int value = 0;
                try {
                    value = Integer.parseInt(
                                oldstr.substring(i, i+digits), 8);
                } catch (NumberFormatException nfe) {
                    die("invalid octal value for \\0 escape");
                i += digits-1;
                break; /* switch */
            } /* end case '0' */

            case 'x':  {
                if (i+2 > oldstr.length()) {
                    die("string too short for \\x escape");
                boolean saw_brace = false;
                if (oldstr.charAt(i) == '{') {
                        /* ^^^^^^ ok to ignore surrogates here */
                    saw_brace = true;
                int j;
                for (j = 0; j < 8; j++) {

                    if (!saw_brace && j == 2) {
                        break;  /* for */

                     * ASCII test also catches surrogates
                    int ch = oldstr.charAt(i+j);
                    if (ch > 127) {
                        die("illegal non-ASCII hex digit in \\x escape");

                    if (saw_brace && ch == '}') { break; /* for */ }

                    if (! ( (ch >= '0' && ch <= '9')
                            (ch >= 'a' && ch <= 'f')
                            (ch >= 'A' && ch <= 'F')
                            "illegal hex digit #%d '%c' in \\x", ch, ch));

                if (j == 0) { die("empty braces in \\x{} escape"); }
                int value = 0;
                try {
                    value = Integer.parseInt(oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\x escape");
                if (saw_brace) { j++; }
                i += j-1;
                break; /* switch */

            case 'u': {
                if (i+4 > oldstr.length()) {
                    die("string too short for \\u escape");
                int j;
                for (j = 0; j < 4; j++) {
                    /* this also handles the surrogate issue */
                    if (oldstr.charAt(i+j) > 127) {
                        die("illegal non-ASCII hex digit in \\u escape");
                int value = 0;
                try {
                    value = Integer.parseInt( oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\u escape");
                i += j-1;
                break; /* switch */

            case 'U': {
                if (i+8 > oldstr.length()) {
                    die("string too short for \\U escape");
                int j;
                for (j = 0; j < 8; j++) {
                    /* this also handles the surrogate issue */
                    if (oldstr.charAt(i+j) > 127) {
                        die("illegal non-ASCII hex digit in \\U escape");
                int value = 0;
                try {
                    value = Integer.parseInt(oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\U escape");
                i += j-1;
                break; /* switch */

            default:   newstr.append('\\');
            * say(String.format(
            *       "DEFAULT unrecognized escape %c passed through",
            *       cp));
                       break; /* switch */

        saw_backslash = false;

    /* weird to leave one at the end */
    if (saw_backslash) {

    return newstr.toString();

 * Return a string "U+XX.XXX.XXXX" etc, where each XX set is the
 * xdigits of the logical Unicode code point. No bloody brain-damaged
 * UTF-16 surrogate crap, just true logical characters.
 public final static
 String uniplus(String s) {
     if (s.length() == 0) {
         return "";
     /* This is just the minimum; sb will grow as needed. */
     StringBuffer sb = new StringBuffer(2 + 3 * s.length());
     for (int i = 0; i < s.length(); i++) {
         sb.append(String.format("%X", s.codePointAt(i)));
         if (s.codePointAt(i) > Character.MAX_VALUE) {
             i++; /****WE HATES UTF-16! WE HATES IT FOREVERSES!!!****/
         if (i+1 < s.length()) {
     return sb.toString();

private static final
void die(String foa) {
    throw new IllegalArgumentException(foa);

private static final
void say(String what) {

If it helps others, you’re welcome to it — no strings attached. If you improve it, I’d love for you to mail me your enhancements, but you certainly don’t have to.

Replacing a character from a certain index

You can also Use below method if you have to replace string between specific index

def Replace_Substring_Between_Index(singleLine,stringToReplace='',startPos=0,endPos=1):
       singleLine = singleLine[:startPos]+stringToReplace+singleLine[endPos:]
    except Exception as e:
        exception="There is Exception at this step while calling replace_str_index method, Reason = " + str(e)
    return singleLine

How to encrypt and decrypt String with my passphrase in Java (Pc not mobile platform)?

package com.ezeon.util.gen;
import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
/*** Encryption and Decryption of String data; PBE(Password Based Encryption and Decryption)
* @author Vikram
public class CryptoUtil 

    Cipher ecipher;
    Cipher dcipher;
    // 8-byte Salt
    byte[] salt = {
        (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
        (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03
    // Iteration count
    int iterationCount = 19;

    public CryptoUtil() {


     * @param secretKey Key used to encrypt data
     * @param plainText Text input to be encrypted
     * @return Returns encrypted text
     * @throws
     * @throws
     * @throws javax.crypto.NoSuchPaddingException
     * @throws
     * @throws
     * @throws
     * @throws javax.crypto.IllegalBlockSizeException
     * @throws javax.crypto.BadPaddingException
    public String encrypt(String secretKey, String plainText)
            throws NoSuchAlgorithmException,
            BadPaddingException {
        //Key generation for enc and desc
        KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
        // Prepare the parameter to the ciphers
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

        //Enc process
        ecipher = Cipher.getInstance(key.getAlgorithm());
        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
        String charSet = "UTF-8";
        byte[] in = plainText.getBytes(charSet);
        byte[] out = ecipher.doFinal(in);
        String encStr = new String(Base64.getEncoder().encode(out));
        return encStr;

     * @param secretKey Key used to decrypt data
     * @param encryptedText encrypted text input to decrypt
     * @return Returns plain text after decryption
     * @throws
     * @throws
     * @throws javax.crypto.NoSuchPaddingException
     * @throws
     * @throws
     * @throws
     * @throws javax.crypto.IllegalBlockSizeException
     * @throws javax.crypto.BadPaddingException
    public String decrypt(String secretKey, String encryptedText)
            throws NoSuchAlgorithmException,
            IOException {
        //Key generation for enc and desc
        KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
        // Prepare the parameter to the ciphers
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
        //Decryption process; same key will be used for decr
        dcipher = Cipher.getInstance(key.getAlgorithm());
        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
        byte[] enc = Base64.getDecoder().decode(encryptedText);
        byte[] utf8 = dcipher.doFinal(enc);
        String charSet = "UTF-8";
        String plainStr = new String(utf8, charSet);
        return plainStr;
    public static void main(String[] args) throws Exception {
        CryptoUtil cryptoUtil=new CryptoUtil();
        String key="ezeon8547";   
        String plain="This is an important message";
        String enc=cryptoUtil.encrypt(key, plain);
        System.out.println("Original text: "+plain);
        System.out.println("Encrypted text: "+enc);
        String plainAfter=cryptoUtil.decrypt(key, enc);
        System.out.println("Original text after decryption: "+plainAfter);

Insert json file into mongodb

In MS Windows, the mongoimport command has to be run in a normal Windows command prompt, not from the mongodb command prompt.

How do you implement a re-try-catch?

This is an old question but a solution is still relevant. Here is my generic solution in Java 8 without using any third party library:

public interface RetryConsumer<T> {
    T evaluate() throws Throwable;
public interface RetryPredicate<T> {
    boolean shouldRetry(T t);
public class RetryOperation<T> {
    private RetryConsumer<T> retryConsumer;
    private int noOfRetry;
    private int delayInterval;
    private TimeUnit timeUnit;
    private RetryPredicate<T> retryPredicate;
    private List<Class<? extends Throwable>> exceptionList;

    public static class OperationBuilder<T> {
        private RetryConsumer<T> iRetryConsumer;
        private int iNoOfRetry;
        private int iDelayInterval;
        private TimeUnit iTimeUnit;
        private RetryPredicate<T> iRetryPredicate;
        private Class<? extends Throwable>[] exceptionClasses;

        private OperationBuilder() {

        public OperationBuilder<T> retryConsumer(final RetryConsumer<T> retryConsumer) {
            this.iRetryConsumer = retryConsumer;
            return this;

        public OperationBuilder<T> noOfRetry(final int noOfRetry) {
            this.iNoOfRetry = noOfRetry;
            return this;

        public OperationBuilder<T> delayInterval(final int delayInterval, final TimeUnit timeUnit) {
            this.iDelayInterval = delayInterval;
            this.iTimeUnit = timeUnit;
            return this;

        public OperationBuilder<T> retryPredicate(final RetryPredicate<T> retryPredicate) {
            this.iRetryPredicate = retryPredicate;
            return this;

        public final OperationBuilder<T> retryOn(final Class<? extends Throwable>... exceptionClasses) {
            this.exceptionClasses = exceptionClasses;
            return this;

        public RetryOperation<T> build() {
            if (Objects.isNull(iRetryConsumer)) {
                throw new RuntimeException("'#retryConsumer:RetryConsumer<T>' not set");

            List<Class<? extends Throwable>> exceptionList = new ArrayList<>();
            if (Objects.nonNull(exceptionClasses) && exceptionClasses.length > 0) {
                exceptionList = Arrays.asList(exceptionClasses);
            iNoOfRetry = iNoOfRetry == 0 ? 1 : 0;
            iTimeUnit = Objects.isNull(iTimeUnit) ? TimeUnit.MILLISECONDS : iTimeUnit;
            return new RetryOperation<>(iRetryConsumer, iNoOfRetry, iDelayInterval, iTimeUnit, iRetryPredicate, exceptionList);

    public static <T> OperationBuilder<T> newBuilder() {
        return new OperationBuilder<>();

    private RetryOperation(RetryConsumer<T> retryConsumer, int noOfRetry, int delayInterval, TimeUnit timeUnit,
                           RetryPredicate<T> retryPredicate, List<Class<? extends Throwable>> exceptionList) {
        this.retryConsumer = retryConsumer;
        this.noOfRetry = noOfRetry;
        this.delayInterval = delayInterval;
        this.timeUnit = timeUnit;
        this.retryPredicate = retryPredicate;
        this.exceptionList = exceptionList;

    public T retry() throws Throwable {
        T result = null;
        int retries = 0;
        while (retries < noOfRetry) {
            try {
                result = retryConsumer.evaluate();
                if (Objects.nonNull(retryPredicate)) {
                    boolean shouldItRetry = retryPredicate.shouldRetry(result);
                    if (shouldItRetry) {
                        retries = increaseRetryCountAndSleep(retries);
                    } else {
                        return result;
                } else {
                    // no retry condition defined, no exception thrown. This is the desired result.
                    return result;
            } catch (Throwable e) {
                retries = handleException(retries, e);
        return result;

    private int handleException(int retries, Throwable e) throws Throwable {
        if (exceptionList.contains(e.getClass()) || (exceptionList.isEmpty())) {
            // exception is excepted, continue retry.
            retries = increaseRetryCountAndSleep(retries);
            if (retries == noOfRetry) {
                // evaluation is throwing exception, no more retry left. Throw it.
                throw e;
        } else {
            // unexpected exception, no retry required. Throw it.
            throw e;
        return retries;

    private int increaseRetryCountAndSleep(int retries) {
        if (retries < noOfRetry && delayInterval > 0) {
            try {
            } catch (InterruptedException ignore) {
        return retries;

Let's have a test case like:

public void withPredicateAndException() {
    AtomicInteger integer = new AtomicInteger();
    try {
        Integer result = RetryOperation.<Integer>newBuilder()
                .retryConsumer(() -> {
                    int i = integer.incrementAndGet();
                    if (i % 2 == 1) {
                        throw new NumberFormatException("Very odd exception");
                    } else {
                        return i;
                .delayInterval(10, TimeUnit.MILLISECONDS)
                .retryPredicate(value -> value <= 6)
                .retryOn(NumberFormatException.class, EOFException.class)
        Assert.assertEquals(8, result.intValue());
    } catch (Throwable throwable) {;

Where can I find the error logs of nginx, using FastCGI and Django?

Errors are stored in the nginx log file. You can specify it in the root of the nginx configuration file:

error_log  /var/log/nginx/nginx_error.log  warn;

On Mac OS X with Homebrew, the log file was found by default at the following location:


How to apply CSS page-break to print a table with lots of rows?

this is working for me:

  <div class="avoid">
    Cell content.
<style type="text/css">
  .avoid {
    page-break-inside: avoid !important;
    margin: 4px 0 4px 0;  /* to keep the page break from cutting too close to the text in the div */

From this thread: avoid page break inside row of table

Access cell value of datatable

string abc= dt.Rows[0]["column name"].ToString();

UUID max character length

Most databases have a native UUID type these days to make working with them easier. If yours doesn't, they're just 128-bit numbers, so you can use BINARY(16), and if you need the text format frequently, e.g. for troubleshooting, then add a calculated column to generate it automatically from the binary column. There is no good reason to store the (much larger) text form.

How to set the thumbnail image on HTML5 video?

That seems to be an extra image being shown there.

You can try using this

<img src="/images/image_of_video.png" alt="image" />
/* write your code for the video here */

Now using jQuery play the video and hide the image as

$('img').click(function () {
  // use the parameters to play the video now..

Is Python faster and lighter than C++?

It's the same problem with managed and easy to use programming language as always - they are slow (and sometimes memory-eating).

These are languages to do control rather than processing. If I would have to write application to transform images and had to use Python too all the processing could be written in C++ and connected to Python via bindings while interface and process control would be definetely Python.

Return Type for jdbcTemplate.queryForList(sql, object, classType)

A complete solution for JdbcTemplate, NamedParameterJdbcTemplate with or without RowMapper Example.

// Create a Employee table

create table employee(  
id number(10),  
name varchar2(100),  
salary number(10)  

======================================================================= //

public class Employee {
private int id;  
private String name;  
private float salary;  

//no-arg and parameterized constructors  

public Employee(){};

public Employee(int  id, String name, float salary){;;

//getters and setters  
public int getId() {
    return id;
public void setId(int id) { = id;
public String getName() {
    return name;
public void setName(String name) { = name;
public float getSalary() {
    return salary;
public void setSalary(float salary) {
    this.salary = salary;
public String toString(){  
   return id+" "+name+" "+salary;  


========================================================================= //

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

public class EmployeeDao {  
  private JdbcTemplate jdbcTemplate;  
  private NamedParameterJdbcTemplate nameTemplate;  

  public void setnameTemplate(NamedParameterJdbcTemplate template) {  
    this.nameTemplate = template;  

 public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {  
  this.jdbcTemplate = jdbcTemplate;  

 // BY using JdbcTemplate
 public int saveEmployee(Employee e){  
 int id = e.getId();
 String name = e.getName();
 float salary = e.getSalary();
 Object p[] = {id, name, salary};
    String query="insert into employee values(?,?,?)";
      return jdbcTemplate.update(query, p);
    /*String query="insert into employee     values('"+e.getId()+"','"+e.getName()+"','"+e.getSalary()+"')"; 
      return jdbcTemplate.update(query);


//By using NameParameterTemplate
public void insertEmploye(Employee e) {  
String query="insert into employee values (:id,:name,:salary)";  
Map<String,Object> map=new HashMap<String,Object>();  

nameTemplate.execute(query,map,new MyPreparedStatement());

// Updating Employee
public int updateEmployee(Employee e){  
String query="update employee set  name='"+e.getName()+"',salary='"+e.getSalary()+"' where id='"+e.getId()+"' ";  
  return jdbcTemplate.update(query);  
 // Deleting a Employee row
 public int deleteEmployee(Employee e){  
 String query="delete from employee where id='"+e.getId()+"' ";  
 return jdbcTemplate.update(query);  
 //Selecting Single row with condition and also all rows
    public int selectEmployee(Employee e){  
     //String query="select * from employee where id='"+e.getId()+"' ";
      String query="select * from employee";
      List<Map<String, Object>> rows = jdbcTemplate.queryForList(query);
       for(Map<String, Object> row : rows){
          String id = row.get("id").toString();
          String name = (String)row.get("name");
          String salary = row.get("salary").toString();
          System.out.println(id + " " + name + " " + salary );

      return 1;

   // Can use MyrowMapper class an implementation class for RowMapper interface
    public void getAllEmployee()

    String query="select * from employee";
    List<Employee> l = jdbcTemplate.query(query, new MyrowMapper());

    Iterator it=l.iterator();
      Employee e=(Employee);
      System.out.println(e.getId()+" "+e.getName()+" "+e.getSalary());

  //Can use directly a RowMapper implementation class without an object creation
  public List<Employee> getAllEmployee1(){
    return jdbcTemplate.query("select * from employee",new RowMapper<Employee>(){  
      public Employee mapRow(ResultSet rs, int rownumber) throws  SQLException    {  
            Employee e=new Employee();  
            return e;  
     // End of all the function


================================================================ //

 import java.sql.ResultSet;
 import java.sql.SQLException;
 import org.springframework.jdbc.core.RowMapper;

 public class MyrowMapper implements RowMapper<Employee> {

  public Employee mapRow(ResultSet rs, int rownumber) throws SQLException 
    Employee e=new Employee();  
     return e;  

========================================================== //

import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.PreparedStatementCallback;

 public class MyPreparedStatement implements  PreparedStatementCallback<Object> {

 public Object doInPreparedStatement(PreparedStatement ps)
        throws SQLException, DataAccessException {

     return ps.executeUpdate(); 


===================================================================== //

import java.util.List;
import org.springframework.context.ApplicationContext;

public class Test {  

public static void main(String[] args) {  
 ApplicationContext ctx=new     ClassPathXmlApplicationContext("applicationContext.xml");  

 EmployeeDao dao=(EmployeeDao)ctx.getBean("edao"); 

  // By calling constructor for insert
    int status=dao.saveEmployee(new Employee(103,"Ajay",35000));  
 // By calling PreparedStatement
  dao.insertEmploye(new Employee(103,"Roh",25000));

 // By calling setter-getter for update
    Employee e=new Employee(); 
    int status=dao.updateEmployee(e);
 // By calling constructor for update
    int status=dao.updateEmployee(new Employee(102,"Sadhan",15000)); 
 // Deleting a record 
    Employee e=new Employee(); 
    int status=dao.deleteEmployee(e); 
 // Selecting single or all rows
    Employee e=new Employee(); 
    int status=dao.selectEmployee(e);
// Can use MyrowMapper class an implementation class for RowMapper interface


// Can use directly a RowMapper implementation class without an object creation
    List<Employee> list=dao.getAllEmployee1();  
    for(Employee e1:list)  


================================================================== //applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>  

<bean id="ds"        class="org.springframework.jdbc.datasource.DriverManagerDataSource">  
 <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />  
 <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe" />  
 <property name="username" value="hr" />  
 <property name="password" value="hr" />  

 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">  
 <property name="dataSource" ref="ds"></property>  

<bean id="nameTemplate"   
<constructor-arg ref="ds"></constructor-arg>  

<bean id="edao" class="EmployeeDao"> 
<!-- Can use both --> 
<property name="nameTemplate" ref="nameTemplate"></property>
<property name="jdbcTemplate" ref="jdbcTemplate"></property> 


What is this: [Ljava.lang.Object;?

If you are here because of the Liquibase error saying:

Caused By: Precondition Error
Can't detect type of array [Ljava.lang.Short

and you are using

not {

precondition multiple times, then you are facing an old bug:

We can try to execute an above check using bare sqlCheck(Postgres):

SELECT COUNT(i.relname)
    pg_class t,
    pg_class i,
    pg_index ix
    t.oid = ix.indrelid
    and i.oid = ix.indexrelid
    and t.relkind = 'r'
    and t.relname = 'tableName'
    and i.relname = 'indexName';

where tableName - is an index table name and indexName - is an index name

Current date and time as string

#include <chrono>
#include <iostream>

int main()
    std::time_t ct = std::time(0);
    char* cc = ctime(&ct);

    std::cout << cc << std::endl;
    return 0;

Can you break from a Groovy "each" closure?

Nope, you can't abort an "each" without throwing an exception. You likely want a classic loop if you want the break to abort under a particular condition.

Alternatively, you could use a "find" closure instead of an each and return true when you would have done a break.

This example will abort before processing the whole list:

def a = [1, 2, 3, 4, 5, 6, 7]

a.find { 
    if (it > 5) return true // break
    println it  // do the stuff that you wanted to before break
    return false // keep looping



but doesn't print 6 or 7.

It's also really easy to write your own iterator methods with custom break behavior that accept closures:

List.metaClass.eachUntilGreaterThanFive = { closure ->
    for ( value in delegate ) {
        if ( value  > 5 ) break

def a = [1, 2, 3, 4, 5, 6, 7]

a.eachUntilGreaterThanFive {
    println it

Also prints:


Git log to get commits only for a specific branch

BUT I would like to avoid the need of knowing the other branches names.

I don't think this is possible: a branch in Git is always based on another one or at least on another commit, as explained in "git diff doesn't show enough":

enter image description here

You need a reference point for your log to show the right commits.

As mentioned in "GIT - Where did I branch from?":

branches are simply pointers to certain commits in a DAG

So even if git log master..mybranch is one answer, it would still show too many commits, if mybranch is based on myotherbranch, itself based on master.

In order to find that reference (the origin of your branch), you can only parse commits and see in which branch they are, as seen in:

How to change heatmap.2 color range in R?

Here's another option for those not using heatmap.2 (aheatmap is good!)

Make a sequential vector of 100 values from min to max of your input matrix, find value closest to 0 in that, make two vector of colours to and from desired midpoint, combine and use them:

breaks <- seq(from=min(range(inputMatrix)), to=max(range(inputMatrix)), length.out=100)
midpoint <- which.min(abs(breaks - 0))
rampCol1 <- colorRampPalette(c("forestgreen", "darkgreen", "black"))(midpoint)
rampCol2 <- colorRampPalette(c("black", "darkred", "red"))(100-(midpoint+1))
rampCols <- c(rampCol1,rampCol2)

mkdir -p functionality in Python

Function declaration;

import os
def mkdir_p(filename):

        if not os.path.exists(folder):  
        return True
        return False

usage :

filename = "./download/80c16ee665c8/upload/backup/mysql/2014-12-22/adclient_sql_2014-12-22-13-38.sql.gz"

if (mkdir_p(filename):
    print "Created dir :%s" % (os.path.dirname(filename))

How can I match a string with a regex in Bash?

shopt -s nocasematch

if [[ sed-4.2.2.$LINE =~ (yes|y)$ ]]
 then exit 0 

What is the difference between the kernel space and the user space?

Kernel space & virtual space are concepts of virtual doesn't mean Ram(your actual memory) is divided into kernel & User space. Each process is given virtual memory which is divided into kernel & user space.

So saying "The random access memory (RAM) can be divided into two distinct regions namely - the kernel space and the user space." is wrong.

& regarding "kernel space vs user space" thing

When a process is created and its virtual memory is divided into user-space and a kernel-space , where user space region contains data, code, stack, heap of the process & kernel-space contains things such as the page table for the process, kernel data structures and kernel code etc. To run kernel space code, control must shift to kernel mode(using 0x80 software interrupt for system calls) & kernel stack is basically shared among all processes currently executing in kernel space.

How to add a boolean datatype column to an existing table in sql?

The answer given by P????? creates a nullable bool, not a bool, which may be fine for you. For example in C# it would create: bool? AdminApprovednot bool AdminApproved.

If you need to create a bool (defaulting to false):

    ALTER TABLE person
    ADD AdminApproved BIT

SQL Server: Error converting data type nvarchar to numeric

You might need to revise the data in the column, but anyway you can do one of the following:-

1- check if it is numeric then convert it else put another value like 0


2- select only numeric values from the column

where Isnumeric(COLUMNA) = 1

How can I see an the output of my C programs using Dev-C++?

Well when you are writing a c program and want the output log to stay instead of flickering away you only need to import the stdlib.h header file and type "system("PAUSE");" at the place you want the output screen to halt.Look at the example here.The following simple c program prints the product of 5 and 6 i.e 30 to the output window and halts the output window.

#include <stdio.h>
#include <stdlib.h>
int main()
      int a,b,c;
      return 0;

Hope this helped.

Equivalent to AssemblyInfo in dotnet core/csproj

Adding to NightOwl888's answer, you can go one step further and add an AssemblyInfo class rather than just a plain class:

enter image description here

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

Expanding on @Renaud idea, cors now provides a very easy way of doing this:

From cors official documentation found here:

" origin: Configures the Access-Control-Allow-Origin CORS header. Possible values: Boolean - set origin to true to reflect the request origin, as defined by req.header('Origin'), or set it to false to disable CORS. "

Hence we simply do the following:

const app = express();
const corsConfig = {
    credentials: true,
    origin: true,

Lastly I think it is worth mentioning that there are use cases where we would want to allow cross origin requests from anyone; for example, when building a public REST API.

NOTE: I would have liked to leave this as a comment on his answer, but unfortunately I don't have the reputation points.

when do you need .ascx files and how would you use them?

One more use of .ascx files is, they can be used for Partial Page caching in ASP.NET pages. What we have to do is to create an ascx file and then move the controls or portion of the page we need to cache into that control. Then add the @OutputCache directive in the ascx control and it will be cached separately from the parent page. It is used when you don't want to cache the whole page but only a specific portion of the page.

querySelector, wildcard element match?

I was messing/musing on one-liners involving querySelector() & ended up here, & have a possible answer to the OP question using tag names & querySelector(), with credits to @JaredMcAteer for answering MY question, aka have RegEx-like matches with querySelector() in vanilla Javascript

Hoping the following will be useful & fit the OP's needs or everyone else's:

// basically, of before:
var youtubeDiv = document.querySelector('iframe[src=""]')

// after     
var youtubeDiv = document.querySelector('iframe[src^=""]');
// or even, for my needs
var youtubeDiv = document.querySelector('iframe[src*="youtube"]');

Then, we can, for example, get the src stuff, etc ...

//> ""
//> (...)

How can I get the order ID in WooCommerce?

$order = new WC_Order( $post_id ); 

If you

echo $order->id;

then you'll be returned the id of the post from which the order is made. As you've already got that, it's probably not what you want.

echo $order->get_order_number();

will return the id of the order (with a # in front of it). To get rid of the #,

echo trim( str_replace( '#', '', $order->get_order_number() ) );

as per the accepted answer.

What does $_ mean in PowerShell?

According to this website, it's a reference to this, mostly in loops.

$_ (dollar underscore) 'THIS' token. Typically refers to the item inside a foreach loop. Task: Print all items in a collection. Solution. ... | foreach { Write-Host $_ }

Detect if the app was launched/opened from a push notification

M.Othman's answer is correct for apps that don't contain scene delegate For Scene Delegate Apps This worked for me on iOS 13

Here is the code for that should be written in will connect scene

if connectionOptions.notificationResponse == nil { 
//Not opened from push notification
} else {
  //Opened from push notification

Code for app delegate to support earlier versions didFinishLaunchingWithOptions

let notification = launchOptions?[UIApplication.LaunchOptionsKey.remoteNotification]
        if (notification != nil) {

            //Launched from push notification
        } else {

            //Launch from other source

iPhone Navigation Bar Title text color

I do believe proper way to set the colour of UINavigationBar is:

NSDictionary *attributes=[NSDictionary dictionaryWithObjectsAndKeys:[UIColor redColor],UITextAttributeTextColor, nil];
self.titleTextAttributes = attributes;

Code above is written is subclass on UINavigationBar, obviously works without subclassing as well.

how to use free cloud database with android app?

Now there are a lot of cloud providers , providing solutions like MBaaS (Mobile Backend as a Service). Some only give access to cloud database, some will do the user management for you, some let you place code around cloud database and there are facilities of access control, push notifications, analytics, integrated image and file hosting etc.

Here are some providers which have a "free-tier" (may change in future):

  1. Firebase (Google) -
  2. AWS Mobile (Amazon) -
  3. Azure Mobile (Microsoft) -
  4. MongoDB Realm (MongoDB) -
  5. Back4app (Popular) -

Open source solutions:

  1. Parse -
  2. Apache User Grid -
  3. SupaBase (under development) -

Portable way to check if directory exists [Windows/Linux, C]

Use boost::filesystem, that will give you a portable way of doing those kinds of things and abstract away all ugly details for you.

Rock, Paper, Scissors Game Java

You could insert something like this:

personPlay = "B";

while (!personPlay.equals("R") && !personPlay.equals("P") && !personPlay.equals("S")) {

    //Get player's play from input-- note that this is 
    // stored as a string 
    System.out.println("Enter your play: "); 
    personPlay =;

    //Make player's play uppercase for ease of comparison 
    personPlay = personPlay.toUpperCase();

    if (!personPlay.equals("R") && !personPlay.equals("P") && !personPlay.equals("S"))
        System.out.println("Invalid move. Try again.");


How do I handle the window close event in Tkinter?

Matt has shown one classic modification of the close button.
The other is to have the close button minimize the window.
You can reproduced this behavior by having the iconify method
be the protocol method's second argument.

Here's a working example, tested on Windows 7 & 10:

# Python 3
import tkinter
import tkinter.scrolledtext as scrolledtext

root = tkinter.Tk()
# make the top right close button minimize (iconify) the main window
root.protocol("WM_DELETE_WINDOW", root.iconify)
# make Esc exit the program
root.bind('<Escape>', lambda e: root.destroy())

# create a menu bar with an Exit command
menubar = tkinter.Menu(root)
filemenu = tkinter.Menu(menubar, tearoff=0)
filemenu.add_command(label="Exit", command=root.destroy)
menubar.add_cascade(label="File", menu=filemenu)

# create a Text widget with a Scrollbar attached
txt = scrolledtext.ScrolledText(root, undo=True)
txt['font'] = ('consolas', '12')
txt.pack(expand=True, fill='both')


In this example we give the user two new exit options:
the classic File ? Exit, and also the Esc button.

Adding Buttons To Google Sheets and Set value to Cells on clicking

Consider building an Add-on that has an actual button and not using the outdated method of linking an image to a script function.

In the script editor, under the Help menu >> Welcome Screen >> link to Google Sheets Add-on - will give you sample code to use.

How to generate a create table script for an existing table in phpmyadmin?

One more way. Select the target table in the left panel in phpMyAdmin, click on Export tab, unselect Data block and click on Go button.

Get current URL from IFRAME

Some additional information for anyone who might be struggling with this:

You'll be getting null values if you're trying to get URL from iframe before it's loaded. I solved this problem by creating the whole iframe in javascript and getting the values I needed with the onLoad function:

var iframe = document.createElement('iframe');
iframe.onload = function() {

    //some custom settings
    this.width=screen.width;this.height=screen.height; this.passing=0; this.frameBorder="0";

    var href = iframe.contentWindow.location.href;
    var origin = iframe.contentWindow.location.origin;
    var url = iframe.contentWindow.location.url;
    var path = iframe.contentWindow.location.pathname;

    console.log("href: ", href)
    console.log("origin: ", origin)
    console.log("path: ", path)
    console.log("url: ", url)

iframe.src = 'http://localhost/folder/index.html';


Because of the same-origin policy, I had problems when accessing "cross origin" frames - I solved that by running a webserver locally instead of running all the files directly from my disk. In order for all of this to work, you need to be accessing the iframe with the same protocol, hostname and port as the origin. Not sure which of these was/were missing when running all files from my disk.

Also, more on location objects:

scipy.misc module has no attribute imread?

imread is deprecated in SciPy 1.0.0, and will be removed in 1.2.0. Use imageio.imread instead.

import imageio
im = imageio.imread('astronaut.png')
im.shape  # im is a numpy array
(512, 512, 3)
imageio.imwrite('imageio:astronaut-gray.jpg', im[:, :, 0])

How to insert a newline in front of a pattern?

On my mac, the following inserts a single 'n' instead of newline:

sed 's/regexp/\n&/g'

This replaces with newline:

sed "s/regexp/\\`echo -e '\n\r'`/g"

Python foreach equivalent

Its also interesting to observe this

To iterate over the indices of a sequence, you can combine range() and len() as follows:

a = ['Mary', 'had', 'a', 'little', 'lamb']
for i in range(len(a)):
  print(i, a[i])


0 Mary
1 had
2 a
3 little
4 lamb

Edit#1: Alternate way:

When looping through a sequence, the position index and corresponding value can be retrieved at the same time using the enumerate() function.

for i, v in enumerate(['tic', 'tac', 'toe']):
  print(i, v)


0 tic
1 tac
2 toe

iOS UIImagePickerController result image orientation after upload

This what I have found for fixing orientation issue

UIImage *initialImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data = UIImagePNGRepresentation(self.initialImage);

UIImage *tempImage = [UIImage imageWithData:data];
UIImage *fixedOrientationImage = [UIImage imageWithCGImage:tempImage.CGImage
initialImage = fixedOrientationImage;


UIImage *initialImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data = UIImagePNGRepresentation(self.initialImage);

initialImage = [UIImage imageWithCGImage:[UIImage imageWithData:data].CGImage

How can I combine flexbox and vertical scroll in a full-height app?

The current spec says this regarding flex: 1 1 auto:

Sizes the item based on the width/height properties, but makes them fully flexible, so that they absorb any free space along the main axis. If all items are either flex: auto, flex: initial, or flex: none, any positive free space after the items have been sized will be distributed evenly to the items with flex: auto.

It sounds to me like if you say an element is 100px tall, it is treated more like a "suggested" size, not an absolute. Because it is allowed to shrink and grow, it takes up as much space as its allowed to. That's why adding this line to your "main" element works: height: 0 (or any other smallish number).

jQuery onclick event for <li> tags

You can get the ID, or any other attribute, using jQuery's attrib function.

$(' li').attrib('id');

To get the menu text, which is in the t span, you can do this:

$(' li').children('span.t').html();

To change the HTML is just as easy:

$(' li').children('span.t').html("I'm different");

Of course, if you wanted to get all the span.t's in the first place, it would be simpler to do:

$(' li span.t').html();

But I'm assuming you've already got the li's, and want to use child() to find something within that element.

How can I hide select options with JavaScript? (Cross browser)

Hiding an <option> element is not in the spec. But you can disable them, which should work cross-browser.

$('option.hide').prop('disabled', true);

How add unique key to existing table (with non uniques rows)

I had to solve a similar problem. I inherited a large source table from MS Access with nearly 15000 records that did not have a primary key, which I had to normalize and make CakePHP compatible. One convention of CakePHP is that every table has a the primary key, that it is first column and that it is called 'id'. The following simple statement did the trick for me under MySQL 5.5:

ALTER TABLE `database_name`.`table_name` 

This added a new column 'id' of type integer in front of the existing data ("FIRST" keyword). The AUTO_INCREMENT keyword increments the ids starting with 1. Now every dataset has a unique numerical id. (Without the AUTO_INCREMENT statement all rows are populated with id = 0).

What does the CSS rule "clear: both" do?

When you want one element placed at the bottom other element you use this code in CSS. It is used for floats.

If you float content you can float left or right... so in a common layout you might have a left nav, a content div and a footer.

To ensure the footer stays below both of these floats (if you have floated left and right) then you put the footer as clear: both.

This way it will stay below both floats.

(If you are only clearing left then you only really need to clear: left;.)

Go through this tutorial:

UnsupportedClassVersionError: JVMCFRE003 bad major version in WebSphere AS 7

In eclipse, Go to Project->Properties->Java build Path->Order and Export. If you are using multiple JREs, try like jdk and ibm. Order should start with jdk and then IBM. This is how my issue was resolved.

Passing arguments to require (when loading module)

I'm not sure if this will still be useful to people, but with ES6 I have a way to do it that I find clean and useful.

class MyClass { 
  constructor ( arg1, arg2, arg3 )
  myFunction1 () {...}
  myFunction2 () {...}
  myFunction3 () {...}

module.exports = ( arg1, arg2, arg3 ) => { return new MyClass( arg1,arg2,arg3 ) }

And then you get your expected behaviour.

var MyClass = require('/MyClass.js')( arg1, arg2, arg3 )

HTML tag <a> want to add both href and onclick working

Use jQuery. You need to capture the click event and then go on to the website.

$("#myHref").on('click', function() {_x000D_
  alert("inside onclick");_x000D_
  window.location = "";_x000D_
<script src=""></script>_x000D_
<a href="#" id="myHref">Click me</a>

How do I delete virtual interface in Linux?

You can use sudo ip link delete to remove the interface.

How can I one hot encode in Python?

Short Answer

Here is a function to do one-hot-encoding without using numpy, pandas, or other packages. It takes a list of integers, booleans, or strings (and perhaps other types too).

import typing

def one_hot_encode(items: list) -> typing.List[list]:
    results = []
    # find the unique items (we want to unique items b/c duplicate items will have the same encoding)
    unique_items = list(set(items))
    # sort the unique items
    sorted_items = sorted(unique_items)
    # find how long the list of each item should be
    max_index = len(unique_items)

    for item in items:
        # create a list of zeros the appropriate length
        one_hot_encoded_result = [0 for i in range(0, max_index)]
        # find the index of the item
        one_hot_index = sorted_items.index(item)
        # change the zero at the index from the previous line to a one
        one_hot_encoded_result[one_hot_index] = 1
        # add the result

    return results


one_hot_encode([2, 1, 1, 2, 5, 3])

# [[0, 1, 0, 0],
#  [1, 0, 0, 0],
#  [1, 0, 0, 0],
#  [0, 1, 0, 0],
#  [0, 0, 0, 1],
#  [0, 0, 1, 0]]
one_hot_encode([True, False, True])

# [[0, 1], [1, 0], [0, 1]]
one_hot_encode(['a', 'b', 'c', 'a', 'e'])

# [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [1, 0, 0, 0], [0, 0, 0, 1]]

Long(er) Answer

I know there are already a lot of answers to this question, but I noticed two things. First, most of the answers use packages like numpy and/or pandas. And this is a good thing. If you are writing production code, you should probably be using robust, fast algorithms like those provided in the numpy/pandas packages. But, for the sake of education, I think someone should provide an answer which has a transparent algorithm and not just an implementation of someone else's algorithm. Second, I noticed that many of the answers do not provide a robust implementation of one-hot encoding because they do not meet one of the requirements below. Below are some of the requirements (as I see them) for a useful, accurate, and robust one-hot encoding function:

A one-hot encoding function must:

  • handle list of various types (e.g. integers, strings, floats, etc.) as input
  • handle an input list with duplicates
  • return a list of lists corresponding (in the same order as) to the inputs
  • return a list of lists where each list is as short as possible

I tested many of the answers to this question and most of them fail on one of the requirements above.

How to get file creation & modification date/times in Python?

Getting some sort of modification date in a cross-platform way is easy - just call os.path.getmtime(path) and you'll get the Unix timestamp of when the file at path was last modified.

Getting file creation dates, on the other hand, is fiddly and platform-dependent, differing even between the three big OSes:

Putting this all together, cross-platform code should look something like this...

import os
import platform

def creation_date(path_to_file):
    Try to get the date that a file was created, falling back to when it was
    last modified if that isn't possible.
    See for explanation.
    if platform.system() == 'Windows':
        return os.path.getctime(path_to_file)
        stat = os.stat(path_to_file)
            return stat.st_birthtime
        except AttributeError:
            # We're probably on Linux. No easy way to get creation dates here,
            # so we'll settle for when its content was last modified.
            return stat.st_mtime

Pentaho Data Integration SQL connection

In addition to the other answers here, here's how you can do it on Ubuntu (14.04):

sudo apt-get install libmysql-java

this will download mysql-connector-java-5.x.x.jar to /usr/share/java/, which i believe also automatically creates a symlink named mysql-connector-java.jar.

Then, create a symlink in /your/path/to/data-integration/lib/:

ln -s /usr/share/java/mysql-connector-java.jar /your/path/to/data-integration/lib/mysql-connector-java.jar

python max function using 'key' and lambda expression

How does the max function work?

It looks for the "largest" item in an iterable. I'll assume that you can look up what that is, but if not, it's something you can loop over, i.e. a list or string.

What is use of the keyword key in max function? I know it is also used in context of sort function

Key is a lambda function that will tell max which objects in the iterable are larger than others. Say if you were sorting some object that you created yourself, and not something obvious, like integers.

Meaning of the lambda expression? How to read them? How do they work?

That's sort of a larger question. In simple terms, a lambda is a function you can pass around, and have other pieces of code use it. Take this for example:

def sum(a, b, f):
    return (f(a) + f(b))

This takes two objects, a and b, and a function f. It calls f() on each object, then adds them together. So look at this call:

>>> sum(2, 2, lambda a:  a * 2)

sum() takes 2, and calls the lambda expression on it. So f(a) becomes 2 * 2, which becomes 4. It then does this for b, and adds the two together.

In not so simple terms, lambdas come from lambda calculus, which is the idea of a function that returns a function; a very cool math concept for expressing computation. You can read about that here, and then actually understand it here.

It's probably better to read about this a little more, as lambdas can be confusing, and it's not immediately obvious how useful they are. Check here.

SQL keys, MUL vs PRI vs UNI

Walkthough on what is MUL, PRI and UNI in MySQL?

From the MySQL 5.7 documentation:

  • If Key is PRI, the column is a PRIMARY KEY or is one of the columns in a multiple-column PRIMARY KEY.
  • If Key is UNI, the column is the first column of a UNIQUE index. (A UNIQUE index permits multiple NULL values, but you can tell whether the column permits NULL by checking the Null field.)
  • If Key is MUL, the column is the first column of a nonunique index in which multiple occurrences of a given value are permitted within the column.

Live Examples

Control group, this example has neither PRI, MUL, nor UNI:

mysql> create table penguins (foo INT);
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  |     | NULL    |       |
1 row in set (0.00 sec)

A table with one column and an index on the one column has a MUL:

mysql> create table penguins (foo INT, index(foo));
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  | MUL | NULL    |       |
1 row in set (0.00 sec)

A table with a column that is a primary key has PRI

mysql> create table penguins (foo INT primary key);
Query OK, 0 rows affected (0.02 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | NO   | PRI | NULL    |       |
1 row in set (0.00 sec)

A table with a column that is a unique key has UNI:

mysql> create table penguins (foo INT unique);
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  | UNI | NULL    |       |
1 row in set (0.00 sec)

A table with an index covering foo and bar has MUL only on foo:

mysql> create table penguins (foo INT, bar INT, index(foo, bar));
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  | MUL | NULL    |       |
| bar   | int(11) | YES  |     | NULL    |       |
2 rows in set (0.00 sec)

A table with two separate indexes on two columns has MUL for each one

mysql> create table penguins (foo INT, bar int, index(foo), index(bar));
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  | MUL | NULL    |       |
| bar   | int(11) | YES  | MUL | NULL    |       |
2 rows in set (0.00 sec)

A table with an Index spanning three columns has MUL on the first:

mysql> create table penguins (foo INT, 
       bar INT, 
       baz INT, 
       INDEX name (foo, bar, baz));
Query OK, 0 rows affected (0.01 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| foo   | int(11) | YES  | MUL | NULL    |       |
| bar   | int(11) | YES  |     | NULL    |       |
| baz   | int(11) | YES  |     | NULL    |       |
3 rows in set (0.00 sec)

A table with a foreign key that references another table's primary key is MUL

mysql> create table penguins(id int primary key);
Query OK, 0 rows affected (0.01 sec)

mysql> create table skipper(id int, foreign key(id) references penguins(id));
Query OK, 0 rows affected (0.01 sec)

mysql> desc skipper;
| Field | Type    | Null | Key | Default | Extra |
| id    | int(11) | YES  | MUL | NULL    |       |
1 row in set (0.00 sec)

mysql> desc penguins;
| Field | Type    | Null | Key | Default | Extra |
| id    | int(11) | NO   | PRI | NULL    |       |
1 row in set (0.00 sec)

Stick that in your neocortex and set the dial to "frappe".

onclick event function in JavaScript

//$(document).ready(function () {
function showcontent() {
        document.getElementById("demo22").innerHTML = "Hello World";
//});// end of ready function

I had the same problem where onclick function calls would not work. I had included the function inside the usual "$(document).ready(function(){});" block used to wrap jquery scripts. Commenting this block out solved the problem.

How to update one file in a zip archive

Use the update flag: -u


zip -ur myFolder

This command will compress and add myFolder (and it's contents) to the

Advanced Usage:

The update flag actually compares the incoming files against the existing ones and will either add new files, or update existing ones.

Therefore, if you want to add/update a specific subdirectory within the zip file, just update the source as desired, and then re-zip the entire source with the -u flag. Only the changed files will be zipped.

If you don't have access to the source files, you can unzip the zip file, then update the desired files, and then re-zip with the -u flag. Again, only the changed files will be zipped.


Original Source Structure

+-- file1.txt
+-- file2.txt
+-- ChildDir
¦   +-- file3.txt
¦   +-- Logs
¦   ¦   +-- logs1.txt
¦   ¦   +-- logs2.txt
¦   ¦   +-- logs3.txt

Updated Source Structure

+-- file1.txt
+-- file2.txt
+-- ChildDir
¦   +-- file3.txt
¦   +-- Logs
¦   ¦   +-- logs1.txt
¦   ¦   +-- logs2.txt
¦   ¦   +-- logs3.txt 
¦   ¦   +-- logs4.txt <-- NEW FILE 


$ zip -ur ParentDir 
> updating: ParentDir/ChildDir/Logs (stored 0%)
>   adding: ParentDir/ChildDir/Logs/logs4.txt (stored 96%)

Drop a temporary table if it exists

From SQL Server 2016 you can just use


On previous versions you can use

/*Then it exists*/
   client_id INT

You could also consider truncating the table instead rather than dropping and recreating.

     client_id INT

How to convert NUM to INT in R?

You can use convert from hablar to change a column of the data frame quickly.


x <- tibble(var = c(1.34, 4.45, 6.98))

x %>% 

gives you:

# A tibble: 3 x 1
1     1
2     4
3     6

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

date +%Y:%m:%d|awk -vFS=":" -vOFS=":" '{$3=$3-1;print}'

Multithreading in Bash

You can run several copies of your script in parallel, each copy for different input data, e.g. to process all *.cfg files on 4 cores:

    ls *.cfg | xargs -P 4 -n 1

The script takes just one parameters (as enforced by -n)

How to make connection to Postgres via Node.js

Slonik is an alternative to answers proposed by Kuberchaun and Vitaly.

Slonik implements safe connection handling; you create a connection pool and connection opening/handling is handled for you.

import {
} from 'slonik';

const pool = createPool('postgres://user:password@host:port/database');

return pool.connect((connection) => {
  // You are now connected to the database.
  return connection.query(sql`SELECT foo()`);
  .then(() => {
    // You are no longer connected to the database.

postgres://user:password@host:port/database is your connection string (or more canonically a connection URI or DSN).

The benefit of this approach is that your script ensures that you never accidentally leave hanging connections.

Other benefits for using Slonik include:

What is the best way to return different types of ResponseEntity in Spring MVC or Spring-Boot

I recommend using Spring's @ControllerAdvice to handle errors. Read this guide for a good introduction, starting at the section named "Spring Boot Error Handling". For an in-depth discussion, there's an article in the blog that was updated on April, 2018.

A brief summary on how this works:

  • Your controller method should only return ResponseEntity<Success>. It will not be responsible for returning error or exception responses.
  • You will implement a class that handles exceptions for all controllers. This class will be annotated with @ControllerAdvice
  • This controller advice class will contain methods annotated with @ExceptionHandler
  • Each exception handler method will be configured to handle one or more exception types. These methods are where you specify the response type for errors
  • For your example, you would declare (in the controller advice class) an exception handler method for the validation error. The return type would be ResponseEntity<Error>

With this approach, you only need to implement your controller exception handling in one place for all endpoints in your API. It also makes it easy for your API to have a uniform exception response structure across all endpoints. This simplifies exception handling for your clients.

What is "entropy and information gain"?

I really recommend you read about Information Theory, bayesian methods and MaxEnt. The place to start is this (freely available online) book by David Mackay:

Those inference methods are really far more general than just text mining and I can't really devise how one would learn how to apply this to NLP without learning some of the general basics contained in this book or other introductory books on Machine Learning and MaxEnt bayesian methods.

The connection between entropy and probability theory to information processing and storing is really, really deep. To give a taste of it, there's a theorem due to Shannon that states that the maximum amount of information you can pass without error through a noisy communication channel is equal to the entropy of the noise process. There's also a theorem that connects how much you can compress a piece of data to occupy the minimum possible memory in your computer to the entropy of the process that generated the data.

I don't think it's really necessary that you go learning about all those theorems on communication theory, but it's not possible to learn this without learning the basics about what is entropy, how it's calculated, what is it's relationship with information and inference, etc...

How to use null in switch

switch (String.valueOf(value)){
    case "null":

Get the last item in an array

If one wants to get the last element in one go, he/she may use Array#splice():

lastElement = document.location.href.split('/').splice(-1,1);

Here, there is no need to store the split elements in an array, and then get to the last element. If getting last element is the only objective, this should be used.

Note: This changes the original array by removing its last element. Think of splice(-1,1) as a pop() function that pops the last element.

Lookup City and State by Zip Google Geocode Api

I found a couple of ways to do this with web based APIs. I think the US Postal Service would be the most accurate, since Zip codes are their thing, but Ziptastic looks much easier.

Using the US Postal Service HTTP/XML API

According to this page on the US Postal Service website which documents their XML based web API, specifically Section 4.0 (page 22) of this PDF document, they have a URL where you can send an XML request containing a 5 digit Zip Code and they will respond with an XML document containing the corresponding City and State.

According to their documentation, here's what you would send:

http://SERVERNAME/ShippingAPITest.dll?API=CityStateLookup&XML=<CityStateLookupRequest%20USERID="xxxxxxx"><ZipCode ID= "0"><Zip5>90210</Zip5></ZipCode></CityStateLookupRequest>

And here's what you would receive back:

<?xml version="1.0"?> 
    <ZipCode ID="0"> 
        <City>BEVERLY HILLS</City> 

USPS does require that you register with them before you can use the API, but, as far as I could tell, there is no charge for access. By the way, their API has some other features: you can do Address Standardization and Zip Code Lookup, as well as the whole suite of tracking, shipping, labels, etc.

Using the Ziptastic HTTP/JSON API (no longer supported)

Update: As of August 13, 2017, Ziptastic is now a paid API and can be found here

This is a pretty new service, but according to their documentation, it looks like all you need to do is send a GET request to, like so:


And they will return a JSON object along the lines of:

{"country": "US", "state": "MI", "city": "OWOSSO"}

Indeed, it works. You can test this from a command line by doing something like:


Getting error "No such module" using Xcode, but the framework is there

The solution for me was. Inside of the targets -> Build Settings -> Framework Search Paths and adding $(inherited). However if it is a cocoapods your answer probably inside of output in terminal.

What is the MySQL JDBC driver connection string?

For Mysql, the jdbc Driver connection string is com.mysql.jdbc.Driver. Use the following code to get connected:-

class DBConnection {
   private static Connection con = null;
   private static String USERNAME = "your_mysql_username";
   private static String PASSWORD = "your_mysql_password";
   private static String DRIVER = "com.mysql.jdbc.Driver";
   private static String URL = "jdbc:mysql://localhost:3306/database_name";

   public static Connection getDatabaseConnection(){
       return con = DriverManager.getConnection(URL,USERNAME,PASSWORD);

How to reduce a huge excel file

I wrote a VBA file to add a tool cleaning these abnormally biggest file. This script clear all columns and rows after the last cells realy used to reset the last cells ( [Ctrl]+[End] ), and it also provides enable images compression.

I dev an AddIns with auto install (just run it with macro enabled) to include in context menu many new buttons:

  1. Optimize
  2. Optimize and Save
  3. Disable Optimizer

Context menu after install it

This is based on KB of Microsoft office 2003 and answer of PP. with personals improvement :

  1. add compression of images
  2. fix bug for Columns
  3. feat compatibility with excel 2007 - 2010 - ... (more than 255 columns)

SOLUTION > you can download my *.xlam file ToolsKit

the main code is

Sub ClearExcessRowsAndColumns()
    Dim ar As Range, r As Double, c As Double, tr As Double, tc As Double
    Dim wksWks As Worksheet, ur As Range, arCount As Integer, i As Integer
    Dim blProtCont As Boolean, blProtScen As Boolean, blProtDO As Boolean
    Dim shp As Shape
    Application.ScreenUpdating = False
    On Error Resume Next
    For Each wksWks In ActiveWorkbook.Worksheets
      'Store worksheet protection settings and unprotect if protected.
      blProtCont = wksWks.ProtectContents
      blProtDO = wksWks.ProtectDrawingObjects
      blProtScen = wksWks.ProtectScenarios
      wksWks.Unprotect ""
      If Err.Number = 1004 Then
         MsgBox "'" & wksWks.Name & "' is protected with a password and cannot be checked.", vbInformation
         Application.StatusBar = "Checking " & wksWks.Name & ", Please Wait..."
         r = 0
         c = 0

         'Determine if the sheet contains both formulas and constants
         Set ur = Union(wksWks.UsedRange.SpecialCells(xlCellTypeConstants), wksWks.UsedRange.SpecialCells(xlCellTypeFormulas))
         'If both fails, try constants only
         If Err.Number = 1004 Then
            Set ur = wksWks.UsedRange.SpecialCells(xlCellTypeConstants)
         End If
         'If constants fails then set it to formulas
         If Err.Number = 1004 Then
            Set ur = wksWks.UsedRange.SpecialCells(xlCellTypeFormulas)
         End If
         'If there is still an error then the worksheet is empty
         If Err.Number <> 0 Then
            If wksWks.UsedRange.Address <> "$A$1" Then
               Set ur = Nothing
            End If
         End If
         'On Error GoTo 0
         If Not ur Is Nothing Then
            arCount = ur.Areas.Count
            'determine the last column and row that contains data or formula
            For Each ar In ur.Areas
               i = i + 1
               tr = ar.Range("A1").Row + ar.Rows.Count - 1
               tc = ar.Range("A1").Column + ar.Columns.Count - 1
               If tc > c Then c = tc
               If tr > r Then r = tr
            'Determine the area covered by shapes
            'so we don't remove shading behind shapes
            For Each shp In wksWks.Shapes
               tr = shp.BottomRightCell.Row
               tc = shp.BottomRightCell.Column
               If tc > c Then c = tc
               If tr > r Then r = tr
            Application.StatusBar = "Clearing Excess Cells in " & wksWks.Name & ", Please Wait..."
            Set ur = wksWks.Rows(r + 1 & ":" & wksWks.Rows.Count)
                'Reset row height which can also cause the lastcell to be innacurate
                ur.EntireRow.RowHeight = wksWks.StandardHeight

            Set ur = wksWks.Columns(ColLetter(c + 1) & ":" & ColLetter(wksWks.Columns.Count))
                'Reset column width which can also cause the lastcell to be innacurate
                ur.EntireColumn.ColumnWidth = wksWks.StandardWidth
         End If
      End If
      'Reset protection.
      wksWks.Protect "", blProtDO, blProtCont, blProtScen
    Application.StatusBar = False
    ' prepare les combinaison de touches pour la validation automatique de la fenetre
    ' Application.SendKeys "%(oe)~{TAB}~"

    ' ouvre la fenetre de compression des images
    Application.CommandBars.ExecuteMso "PicturesCompress"
    Application.ScreenUpdating = True
End Sub

Function ColLetter(ColNumber As Integer) As String
    ColLetter = Left(Cells(1, ColNumber).Address(False, False), Len(Cells(1, ColNumber).Address(False, False)) - 1)
End Function

How to show grep result with complete path or file name


grep somethingtosearch *.log

and the filenames will be printed out along with the matches.

Push local Git repo to new remote including all branches and tags

This is the most concise way I have found, provided the destination is empty. Switch to an empty folder and then:

# Note the period for cwd >>>>>>>>>>>>>>>>>>>>>>>> v
git clone --bare https://your-source-repo/repo.git .
git push --mirror https://your-destination-repo/repo.git

Substitute https://... for file:///your/repo etc. as appropriate.

How to change the background color of the options menu?

If you want to set an arbitrary color, this seem to work rather well for androidx. Tested on KitKat and Pie. Put this into your AppCompatActivity:

@Override public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
    if (name.equals("") &&
            parent.getParent() instanceof FrameLayout) {
            ((View) parent.getParent()).setBackgroundColor(yourFancyColor);
    return super.onCreateView(parent, name, context, attrs);

This sets the color of android.widget.PopupWindow$PopupBackgroundView, which, as you might have guessed, draws the background color. There's no overdraw and you can use semi-transparent colors as well.

How do I delete files programmatically on Android?

Try this one. It is working for me.

handler.postDelayed(new Runnable() {
    public void run() {
        // Set up the projection (we only need the ID)
        String[] projection = { MediaStore.Images.Media._ID };

        // Match on the file path
        String selection = MediaStore.Images.Media.DATA + " = ?";
        String[] selectionArgs = new String[] { imageFile.getAbsolutePath() };

        // Query for the ID of the media matching the file path
        Uri queryUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        ContentResolver contentResolver = getActivity().getContentResolver();
        Cursor c = contentResolver.query(queryUri, projection, selection, selectionArgs, null);

        if (c != null) {
            if (c.moveToFirst()) {
                // We found the ID. Deleting the item via the content provider will also remove the file
                long id = c.getLong(c.getColumnIndexOrThrow(MediaStore.Images.Media._ID));
                Uri deleteUri = ContentUris.withAppendedId(queryUri, id);
                contentResolver.delete(deleteUri, null, null);
            } else {
                // File not found in media store DB
}, 5000);

How do I edit SSIS package files?

If you use the 'Export Data' wizard there is an option to store the configuration as an 'Integration Services Projects' within the SQL Server database . To edit this package follow the instructions from "mikeTheLiar" but instead of searching for a file make a connection to the database and export package.

From "mikeTheLiar": File->New Project->Integration Services Project - Now in solution explorer there is a SSIS Packages folder, right click it and select "Add Existing Package".

Using the default dialog make a connection to the database and open the export package. The package can now be edited.

Angular JS POST request not sending JSON data

    url: '/api/user',
    method: "POST",
    data: angular.toJson(yourData)
}).success(function (data, status, headers, config) {
    $scope.users = data.users;
}).error(function (data, status, headers, config) {
    $scope.status = status + ' ' + headers;

hexadecimal string to byte array in python

There is a built-in function in bytearray that does what you intend.

bytearray.fromhex("de ad be ef 00")

It returns a bytearray and it reads hex strings with or without space separator.

Serialize Class containing Dictionary member

You can't serialize a class that implements IDictionary. Check out this link.

Q: Why can't I serialize hashtables?

A: The XmlSerializer cannot process classes implementing the IDictionary interface. This was partly due to schedule constraints and partly due to the fact that a hashtable does not have a counterpart in the XSD type system. The only solution is to implement a custom hashtable that does not implement the IDictionary interface.

So I think you need to create your own version of the Dictionary for this. Check this other question.

Unresponsive KeyListener for JFrame

in order to capture key events of ALL text fields in a JFrame, one can employ a key event post processor. Here is a working example, after you add the obvious includes.

public class KeyListenerF1Demo extends JFrame implements KeyEventPostProcessor {
    public static final long serialVersionUID = 1L;

    public KeyListenerF1Demo() {

        // Define two labels and two text fields all in a row.
        setLayout(new FlowLayout());

        JLabel label1 = new JLabel("Text1");

        JTextField text1 = new JTextField(10);

        JLabel label2 = new JLabel("Text2");

        JTextField text2 = new JTextField(10);

        // Register a key event post processor.

    public static void main(String[] args) {
        JFrame f = new KeyListenerF1Demo();

    public boolean postProcessKeyEvent(KeyEvent ke) {
        // Check for function key F1 pressed.
        if (ke.getID() == KeyEvent.KEY_PRESSED
                && ke.getKeyCode() == KeyEvent.VK_F1) {

            // Get top level ancestor of focused element.
            Component c = ke.getComponent();
            while (null != c.getParent())
                c = c.getParent();

            // Output some help.
            System.out.println("Help for " + c.getName() + "."
                    + ke.getComponent().getName());

            // Tell keyboard focus manager that event has been fully handled.
            return true;

        // Let keyboard focus manager handle the event further.
        return false;

How can I implement a theme from bootswatch or wrapbootstrap in an MVC 5 project?

The steps to apply a theme are fairly simple. To really understand how everything works together, you'll need to understand what the ASP.NET MVC 5 template is providing out of the box and how you can customize it for your needs.

Note: If you have a basic understanding of how the MVC 5 template works, scroll down to the theming section.

ASP.NET MVC 5 Template: How it works

This walk-through goes over how to create an MVC 5 project and what's going on under the hood. See all the features of MVC 5 Template in this blog.

  1. Create a new project. Under Templates Choose Web > ASP.NET Web Application. Enter a name for your project and click OK.

  2. On the next wizard, choose MVC and click OK. This will apply the MVC 5 template.

    Example of choosing MVC Template

  3. The MVC 5 template creates an MVC application that uses Bootstrap to provide responsive design and theming features. Under the hood, the template includes a bootstrap 3.* nuget package that installs 4 files: bootstrap.css, bootstrap.min.css, bootstrap.js, and bootstrap.min.js.

    Example of installed css and js

  4. Bootstrap is bundled in your application by using the Web Optimization feature. Inspect Views/Shared/_Layout.cshtml and look for




    These two paths refer to bundles set up in App_Start/BundleConfig.cs:

    bundles.Add(new ScriptBundle("~/bundles/bootstrap").Include(
    bundles.Add(new StyleBundle("~/Content/css").Include(
  5. This is what makes it possible to run your application without any configuring up front. Try running your project now.

    Default Application Running

Applying Bootstrap Themes in ASP.NET MVC 5

This walk-through covers how to apply bootstrap themes in an MVC 5 project

  1. First, download the css of the theme you'd like to apply. For this example, I'll be using Bootswatch's Flatly. Include the downloaded flatly.bootstrap.css and flatly.bootstrap.min.css in the Content folder (be sure to Include in Project as well).
  2. Open App_Start/BundleConfig.cs and change the following:

    bundles.Add(new StyleBundle("~/Content/css").Include(

    to include your new theme:

    bundles.Add(new StyleBundle("~/Content/css").Include(
  3. If you're using the default _Layout.cshtml included in the MVC 5 template, you can skip to step 4. If not, as a bare minimum, include these two line in your layout along with your Bootstrap HTML template:

    In your <head>:


    Last line before closing </body>:

  4. Try running your project now. You should see your newly created application now using your theme.

    Default template using flatly theme


Check out this awesome 30 day walk-through guide by James Chambers for more information, tutorials, tips and tricks on how to use Twitter Bootstrap with ASP.NET MVC 5.

Where do I find the bashrc file on Mac?

~/.bashrc is already a path to .bashrc.

If you do echo ~ you'll see that it's a path to your home directory.

Homebrew directory is /usr/local/bin. Homebrew is installed inside it and everything installed by homebrew will be installed there.

For example, if you do brew install python Homebrew will put Python binary in /usr/local/bin.

Finally, to add Homebrew directory to your path you can run echo "export PATH=/usr/local/lib:$PATH" >> ~/.bashrc. It will create .bashrc file if it doesn't exist and then append the needed line to the end.

You can check the result by running tail ~/.bashrc.

Python code to remove HTML tags from a string

Note that this isn't perfect, since if you had something like, say, <a title=">"> it would break. However, it's about the closest you'd get in non-library Python without a really complex function:

import re

TAG_RE = re.compile(r'<[^>]+>')

def remove_tags(text):
    return TAG_RE.sub('', text)

However, as lvc mentions xml.etree is available in the Python Standard Library, so you could probably just adapt it to serve like your existing lxml version:

def remove_tags(text):
    return ''.join(xml.etree.ElementTree.fromstring(text).itertext())

MySQL select with CONCAT condition

The aliases you give are for the output of the query - they are not available within the query itself.

You can either repeat the expression:

SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast 
FROM users
WHERE CONCAT(firstname, ' ', lastname) = "Bob Michael Jones"

or wrap the query

  SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast 
  FROM users) base 
WHERE firstLast = "Bob Michael Jones"

Codesign wants to access key "access" in your keychain, I put in my login password but keeps asking me

I clicked the "Deny" button, and the keychain was off.

I locked the keychain:

enter image description here

And then I entered the login keychain again.

Which Eclipse version should I use for an Android app?

Update July 2017:

From ADT Plugin page, the question must be unasked:

The Eclipse ADT plugin is no longer supported, as per this announcement in June 2015.

The Eclipse ADT plugin has many known bugs and potential security bugs that will not be fixed.

You should immediately switch to use Android Studio, the official IDE for Android. For help transitioning your projects, read Migrate to Android Studio.

Pandas DataFrame concat vs append

I have implemented a tiny benchmark (please find the code on Gist) to evaluate the pandas' concat and append. I updated the code snippet and the results after the comment by ssk08 - thanks alot!

The benchmark ran on a Mac OS X 10.13 system with Python 3.6.2 and pandas 0.20.3.

|        | ignore_index=False              | ignore_index=True               |
| size   | append | concat | append/concat | append | concat | append/concat |
| small  | 0.4635 | 0.4891 | 94.77 %       | 0.4056 | 0.3314 | 122.39 %      |
| medium | 0.5532 | 0.6617 | 83.60 %       | 0.3605 | 0.3521 | 102.37 %      |
| large  | 0.9558 | 0.9442 | 101.22 %      | 0.6670 | 0.6749 | 98.84 %       |

Using ignore_index=False append is slightly faster, with ignore_index=True concat is slightly faster.

tl;dr No significant difference between concat and append.

"Error 1067: The process terminated unexpectedly" when trying to start MySQL

I had the same problem but I was confused with @Vladislav's answer and couldn't seem to find the solution from that. Of course, my problem may not be exactly the same as I encountered the problem when trying to upgrade XAMPP, but it also gave the same Error 1067 message.

With further search I found this:

The answer from that is straightforward, that is, to completely clean up the folder, which doesn't always happen. As in regards to XAMPP, I guess I backed up the necessary files first (data folder from mysql folder and the htdocs folder). Uninstall XAMPP. Check the xampp folder for any content that remains and delete everything. You may want to reboot afterwards, just in case. Then reinstall XAMPP. Copy the backed-up folders back to their respective places, and hopefully, mySql will work again in XAMPP.

This should solve the issue.

iPhone - Grand Central Dispatch main thread

Async means asynchronous and you should use that most of the time. You should never call sync on main thread cause it will lock up your UI until the task is completed. You Here is a better way to do this in Swift:

runThisInMainThread { () -> Void in
    // Run your code like this:

func runThisInMainThread(block: dispatch_block_t) {
    dispatch_async(dispatch_get_main_queue(), block)

Its included as a standard function in my repo, check it out:

Python print statement “Syntax Error: invalid syntax”

Use print("use this bracket -sample text")

In Python 3 print "Hello world" gives invalid syntax error.

To display string content in Python3 have to use this ("Hello world") brackets.

TypeError: 'float' object is not callable

There is an operator missing, likely a *:

-3.7 need_something_here (prof[x])

The "is not callable" occurs because the parenthesis -- and lack of operator which would have switched the parenthesis into precedence operators -- make Python try to call the result of -3.7 (a float) as a function, which is not allowed.

The parenthesis are also not needed in this case, the following may be sufficient/correct:

-3.7 * prof[x]

As Legolas points out, there are other things which may need to be addressed:

2.25 * (1 - math.pow(math.e, (-3.7(prof[x])/2.25))) * (math.e, (0/2.25)))
                                  ^-- op missing
                                                    extra parenthesis --^
               valid but questionable float*tuple --^
                                     expression yields 0.0 always --^

How to set default value to the input[type="date"]

1 - @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
    <input type="date" "myDate">

    var today = new Date();
    $('#myDate').val(today.getFullYear() + '-' + ('0' + (today.getMonth() + 1)).slice(-2) + '-' + ('0' + today.getDate()).slice(-2));

2 - @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
   <input type="datatime-local" id="myLocalDataTime" step="1">

var today = new Date();
$('#myLocalDataTime').val(today.getFullYear() + '-' + ('0' + (today.getMonth() + 1)).slice(-2) + '-' + ('0' + today.getDate()).slice(-2)+'T'+today.getHours()+':'+today.getMinutes());

How to run python script in webpage

Well, OP didn't say server or client side, so i will just leave this here in case someone like me is looking for client side:

Skulpt is a implementation of Python to run at client side. Very interesting, no plugin required, just a simple JS.

Java2D: Increase the line width

You should use setStroke to set a stroke of the Graphics2D object.

The example at gives you some code examples.

The following code produces the image below:

import java.awt.*;
import java.awt.geom.Line2D;
import javax.swing.*;

public class FrameTest {
    public static void main(String[] args) {
        JFrame jf = new JFrame("Demo");
        Container cp = jf.getContentPane();
        cp.add(new JComponent() {
            public void paintComponent(Graphics g) {
                Graphics2D g2 = (Graphics2D) g;
                g2.setStroke(new BasicStroke(10));
                g2.draw(new Line2D.Float(30, 20, 80, 90));
        jf.setSize(300, 200);

enter image description here

(Note that the setStroke method is not available in the Graphics object. You have to cast it to a Graphics2D object.)

This post has been rewritten as an article here.

How to implement LIMIT with SQL Server?

FROM    (
        SELECT  TOP 20
                t.*, ROW_NUMBER() OVER (ORDER BY field1) AS rn
        FROM    table1 t
        ORDER BY
        ) t
WHERE   rn > 10

HTML form with side by side input fields

I would go with Larry K's solution, but you can also set the display to inline-block if you want the benefits of both block and inline elements.

You can do this in the div tag by inserting:


Or in a CSS stylesheet with this method:

div { display:inline-block; }

Hope it helps, but as earlier mentioned, I would personally go for Larry K's solution ;-)

`col-xs-*` not working in Bootstrap 4

I just wondered, why col-xs-6 did not work for me but then I found the answer in the Bootstrap 4 documentation. The class prefix for extra small devices is now col- while in the previous versions it was col-xs.

Bootstrap 4 dropped all col-xs-* classes, so use col-* instead. For example col-xs-6 replaced by col-6.

Best Way to Refresh Adapter/ListView on Android

If you are using LoaderManager try with this statement:

getLoaderManager().restartLoader(0, null, this);

How do you create a Distinct query in HQL

If you need to use new keyword for a custom DTO in your select statement and need distinct elements, use new outside of new like as follows-

select distinct new, a.address, a.status) from Asset as a where ...

How do I move a file from one location to another in Java?

Please try this.

 private boolean filemovetoanotherfolder(String sourcefolder, String destinationfolder, String filename) {
            boolean ismove = false;
            InputStream inStream = null;
            OutputStream outStream = null;

            try {

                File afile = new File(sourcefolder + filename);
                File bfile = new File(destinationfolder + filename);

                inStream = new FileInputStream(afile);
                outStream = new FileOutputStream(bfile);

                byte[] buffer = new byte[1024 * 4];

                int length;
                // copy the file content in bytes
                while ((length = > 0) {

                outStream.write(buffer, 0, length);


                // delete the original file
                ismove = true;
                System.out.println("File is copied successful!");

            } catch (IOException e) {
            return ismove;

Get and Set a Single Cookie with Node.js HTTP Server

First one needs to create cookie (I have wrapped token inside cookie as an example) and then set it in response.To use the cookie in following way install cookieParser


The browser will have it saved in its 'Resource' tab and will be used for every request thereafter taking the initial URL as base

var token = student.generateToken('authentication');
        res.cookie('token', token, {
            expires: new Date( + 9999999),
            httpOnly: false

To get cookie from a request on the server side is easy too.You have to extract the cookie from request by calling 'cookie' property of the request object.

var token = req.cookies.token; // Retrieving Token stored in cookies

Can't create handler inside thread that has not called Looper.prepare() inside AsyncTask for ProgressDialog

The method show() must be called from the User-Interface (UI) thread, while doInBackground() runs on different thread which is the main reason why AsyncTask was designed.

You have to call show() either in onProgressUpdate() or in onPostExecute().

For example:

class ExampleTask extends AsyncTask<String, String, String> {

    // Your onPreExecute method.

    protected String doInBackground(String... params) {
        // Your code.
        if (condition_is_true) {
            this.publishProgress("Show the dialog");
        return "Result";

    protected void onProgressUpdate(String... values) {

MVC 4 @Scripts "does not exist"

When I enter on a page that haves this code:

@section Scripts {

This error occurs: Error. An error occurred while processing your request.

And this exception are recorded on my logs:

System.Web.HttpException (0x80004005): The controller for path '/bundles/jqueryval' was not found or does not implement IController.
   em System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType)

I have tried all tips on this page and none of them solved for me. So I have looked on my Packages folder and noticed that I have two versions for System.Web.Optmization.dll:

  • Microsoft.AspNet.Web.Optimization.1.1.0 (v1.1.30515.0 - 68,7KB)
  • Microsoft.Web.Optimization.1.0.0-beta (v1.0.0.0 - 304KB)

My project was referencing to the older beta version. I only changed the reference to the newer version (69KB) and eveything worked fine.

I think it might help someone.

How can I implement rate limiting with Apache? (requests per second)

In Apache 2.4, there's a new stock module called mod_ratelimit. For emulating modem speeds, you can use mod_dialup. Though I don't see why you just couldn't use mod_ratelimit for everything.

MySQL Data - Best way to implement paging?

There's literature about it:

The main problem happens with the usage of large OFFSETs. They avoid using OFFSET with a variety of techniques, ranging from id range selections in the WHERE clause, to some kind of caching or pre-computing pages.

There are suggested solutions at Use the INDEX, Luke:

PHP: date function to get month of the current date

$unixtime = strtotime($test);
echo date('m', $unixtime); //month
echo date('d', $unixtime); 
echo date('y', $unixtime );

Uninstalling Android ADT

i got the same problem after clicking update plugins, i tried all the suggestions above and failed , the only thing that worked for my is reinstalling android studio..

How to sort a list of strings numerically?

The most recent solution is right. You are reading solutions as a string, in which case the order is 1, then 100, then 104 followed by 2 then 21, then 2001001010, 3 and so forth.

You have to CAST your input as an int instead:

sorted strings:

stringList = (1, 10, 2, 21, 3)

sorted ints:

intList = (1, 2, 3, 10, 21)

To cast, just put the stringList inside int ( blahblah ).


stringList = (1, 10, 2, 21, 3)

newList = int (stringList)

print newList

=> returns (1, 2, 3, 10, 21) 

How do you open a file in C++?

You need to use an ifstream if you just want to read (use an ofstream to write, or an fstream for both).

To open a file in text mode, do the following:

ifstream in("filename.ext", ios_base::in); // the in flag is optional

To open a file in binary mode, you just need to add the "binary" flag.

ifstream in2("filename2.ext", ios_base::in | ios_base::binary ); 

Use the function to read a block of characters (in binary or text mode). Use the getline() function (it's global) to read an entire line.

Git: Permission denied (publickey) fatal - Could not read from remote repository. while cloning Git repository

fix for hub cli tool:

  • git config --global hub.protocol https for long term
  • git remote add OOPS && git push OOPS for immediate fix

This error occurs with the hub command line tool because of their wrong default hub.protocol git-config value. They set repos to


instead of what github actually accepts, namely

Reading LESS=+/"HTTPS instead" man hub will explain where the above "long-term fix" command comes from.

Excel VBA function to print an array to the workbook

On the same theme as other answers, keeping it simple

Sub PrintArray(Data As Variant, Cl As Range)
    Cl.Resize(UBound(Data, 1), UBound(Data, 2)) = Data
End Sub

Sub Test()
    Dim MyArray() As Variant

    ReDim MyArray(1 To 3, 1 To 3) ' make it flexible

    ' Fill array
    '  ...

    PrintArray MyArray, ActiveWorkbook.Worksheets("Sheet1").[A1]
End Sub

How to select a single field for all documents in a MongoDB collection?

Use the Query like this in the shell:

1. Use database_name

e.g: use database_name

2. Which returns only assets particular field information when matched , _id:0 specifies not to display ID in the result

db.collection_name.find( { "Search_Field": "value" }, 
                  { "Field_to_display": 1,_id:0 }  )

Does Java have a path joining method?

This is a start, I don't think it works exactly as you intend, but it at least produces a consistent result.


public class Main
    public static void main(final String[] argv)
        throws Exception
        System.out.println(pathJoin("a", "b"));
        System.out.println(pathJoin("a", "b", "c"));
        System.out.println(pathJoin("a", "b", "", "def"));

    public static String pathJoin(final String ... pathElements)
        final String path;

        if(pathElements == null || pathElements.length == 0)
            path = File.separator;
            final StringBuilder builder;

            builder = new StringBuilder();

            for(final String pathElement : pathElements)
                final String sanitizedPathElement;

                // the "\\" is for Windows... you will need to come up with the 
                // appropriate regex for this to be portable
                sanitizedPathElement = pathElement.replaceAll("\\" + File.separator, "");

                if(sanitizedPathElement.length() > 0)

            path = builder.toString();

        return (path);

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

You can simply chain as many split-path as you need:

$rootPath = $scriptPath | split-path | split-path

MySQL maximum memory usage

in /etc/my.cnf:


performance_schema = 0

table_cache = 0
table_definition_cache = 0
max-connect-errors = 10000

query_cache_size = 0
query_cache_limit = 0


Good work on server with 256MB Memory.

Getting activity from context in android

an Activity is a specialization of Context so, if you have a Context you already know which activity you intend to use and can simply cast a into c; where a is an Activity and c is a Context.

Activity a = (Activity) c;

How does one make random number between range for arc4random_uniform()?

I believe you should do

dice1 = arc4random_uniform(6) + 1;

to get the range 1 - 6. I don't do iOS objective C nor have I any knowledge on swift-language though. The random method should return a value between 0 and 5, and + 1 will make it a value between 1 and 6.

If you need a range between lets say 10 - 30 then just do

int random = arc4random_uniform(21) + 10;

Web scraping with Python

If we think of getting name of items from any specific category then we can do that by specifying the class name of that category using css selector:

import requests ; from bs4 import BeautifulSoup

soup = BeautifulSoup(requests.get('').text, "lxml")
for link in'div._2kSfQ4'):

This is the partial search results:

Puma, USPA, Adidas & moreUp to 70% OffMen's Shoes
Shirts, T-Shirts...Under ?599For Men
Nike, UCB, Adidas & moreUnder ?999Men's Sandals, Slippers
Philips & moreStarting ?99LED Bulbs & Emergency Lights

Where does System.Diagnostics.Debug.Write output appear?

For VB.NET the following applies. You have to select "Debug" AND make sure that you "Start Debugging". This can be reached by pressing F5.

Also the Console.WriteLine will only display messages when building as "Release" in your Output window.

As mentioned before, open the Output window with View ? Output AND make sure to select either "Build" if you want to see Console.WriteLine messages or "Debug" if you want to see Debug.WriteLine or Trace.WriteLine messages.

How to dismiss AlertDialog in android

To dismiss or cancel AlertDialog.Builder

dialog.setNegativeButton("?????", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialogInterface, int i) {

you call dismiss() on the dialog interface

How to get the index of a maximum element in a NumPy array along one axis

>>> import numpy as np
>>> a = np.array([[1,2,3],[4,3,1]])
>>> i,j = np.unravel_index(a.argmax(), a.shape)
>>> a[i,j]

Re-assign host access permission to MySQL user

The more general answer is

UPDATE mysql.user SET host = {newhost} WHERE user = {youruser}

Table border left and bottom

Give a class .border-lb and give this CSS

.border-lb {border: 1px solid #ccc; border-width: 0 0 1px 1px;}

And the HTML

<table width="770">
    <td class="border-lb">picture (border only to the left and bottom ) </td>
    <td class="border-lb">picture (border only to the left and bottom) </td>



Hide Signs that Meteor.js was Used

The amount of hacks you would need to go through to completely hide the fact your site is built by Meteor.js is absolutely ridiculous. You would have to strip essentially all core functionality and just serve straight up html, completely defeating the purpose of using the framework anyway.

That being said, I suggest looking at

You enter a url, and it reveals a ton of information about a site. If you only need to "fool" engines like this, there may be simple solutions.