Programs & Examples On #Seam carving

how to get selected row value in the KendoUI

There is better way. I'm using it in pages where I'm using kendo angularJS directives and grids has'nt IDs...

change: function (e) {
   var selectedDataItem = e != null ? e.sender.dataItem( : null;

Open a facebook link by native Facebook app on iOS

swift 3

if let url = URL(string: "fb://profile/<id>") {
        if #available(iOS 10, *) {
  , options: [:],completionHandler: { (success) in
                print("Open fb://profile/<id>: \(success)")
        } else {
            let success = UIApplication.shared.openURL(url)
            print("Open fb://profile/<id>: \(success)")

Find duplicate records in a table using SQL Server

Try this

with T1 AS
SELECT E.*,T1.[COUNT] FROM Employees E INNER JOIN T1 ON T1.LastName = E.LastName

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

I found the other examples unclear, so I did my own test which confirmed that a class instance is passed by reference and as such actions done to the class will affect the source instance.

In other words, my Increment method modifies its parameter myClass everytime its called.

class Program
    static void Main(string[] args)
        MyClass myClass = new MyClass();
        Console.WriteLine(myClass.Value);  // Displays 1
        Console.WriteLine(myClass.Value);  // Displays 2
        Console.WriteLine(myClass.Value);  // Displays 3           
        Console.WriteLine(myClass.Value);  // Displays 4
        Console.WriteLine("Hit Enter to exit.");

    public static void Increment(MyClass myClassRef)

public class MyClass
    public int Value {get;set;}
    public MyClass()
        Value = 1;

How do I delete a local repository in git?

Delete the .git directory in the root-directory of your repository if you only want to delete the git-related information (branches, versions).

If you want to delete everything (git-data, code, etc), just delete the whole directory.

.git directories are hidden by default, so you'll need to be able to view hidden files to delete it.

How to add parameters to HttpURLConnection using POST using NameValuePair

I think I found exactly what you need. It may help others.

You can use the method UrlEncodedFormEntity.writeTo(OutputStream).

UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nvp); 

OutputStream output = null;
try {
  output = http.getOutputStream();    
} finally {
 if (output != null) try { output.close(); } catch (IOException ioe) {}

How to run a makefile in Windows?

I tried with cygwin & gnuwin, and didn't worked for me, I guess because the makefile used mainly specific linux code.

What it worked was use Ubuntu Bash for Windows 10. This is a Marvel if you come from MAC as it is my case:

  1. To install the Ubuntu Bash:
  2. Once in the console, to install make simply type "make" and it gives the instructions to download it.


  1. Useful enable copy / paste on bash: Copy Paste in Bash on Ubuntu on Windows
  2. In my case the make called Maven, so I have to install it as well:
  3. To access windows filesystem C: drive, for example: "cd /mnt/c/"

Hope it helps

How can I exclude one word with grep?

If your grep supports Perl regular expression with -P option you can do (if bash; if tcsh you'll need to escape the !):

grep -P '(?!.*unwanted_word)keyword' file


$ cat file

Let us now list all foo except foo3

$ grep -P '(?!.*foo3)foo' file

Getting JSONObject from JSONArray

Here is your json:

    "syncresponse": {
       "synckey": "2011-09-30 14:52:00",
        "createdtrs": [

        "modtrs": [

        "deletedtrs": [
           "companyid": "UTB17",
           "username": "DA",
           "date": "2011-09-26",
           "reportid": "31341"

and it's parsing:

JSONObject object = new JSONObject(result);
String syncresponse = object.getString("syncresponse");
JSONObject object2 = new JSONObject(syncresponse);
String synckey = object2.getString("synckey");
JSONArray jArray1 = object2.getJSONArray("createdtrs");
JSONArray jArray2 = object2.getJSONArray("modtrs");
JSONArray jArray3 = object2.getJSONArray("deletedtrs");
for(int i = 0; i < jArray3 .length(); i++)
   JSONObject object3 = jArray3.getJSONObject(i);
   String comp_id = object3.getString("companyid");
   String username = object3.getString("username");
   String date = object3.getString("date");
   String report_id = object3.getString("reportid");

XSS filtering function in PHP

I found a solution for my problem with the posts with german umlaut. To provide from totally cleaning (killing) the posts, i encode the incoming data:

    *$data = utf8_encode($data);
    ... function ...*

And at last i decode the output to get correct signs:

    *$data = utf8_decode($data);*

Now the post go through the filter function and i get a correct result...

How to check if a file exists in the Documents directory in Swift?

Check the below code:

Swift 1.2

let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String

let getImagePath = paths.stringByAppendingPathComponent("SavedFile.jpg")

let checkValidation = NSFileManager.defaultManager()

if (checkValidation.fileExistsAtPath(getImagePath))
    println("FILE AVAILABLE");
    println("FILE NOT AVAILABLE");

Swift 2.0

let paths = NSURL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0])
let getImagePath = paths.URLByAppendingPathComponent("SavedFile.jpg")

let checkValidation = NSFileManager.defaultManager()

if (checkValidation.fileExistsAtPath("\(getImagePath)"))
    print("FILE AVAILABLE");
    print("FILE NOT AVAILABLE");

How to restore PostgreSQL dump file into Postgres databases? the terminal.

2.backup your database with following command

your postgres bin - /opt/PostgreSQL/9.1/bin/

your source database server -

your backup file location and name - /home/dinesh/db/mydb.backup

your source db name - mydatabase

/opt/PostgreSQL/9.1/bin/pg_dump --host '' --port 5432 --username "postgres" --no-password --format custom --blobs --file "/home/dinesh/db/mydb.backup" "mydatabase"

3.restore mydb.backup file into destination.

your destination server - localhost

your destination database name - mydatabase

create database for restore the backup.

/opt/PostgreSQL/9.1/bin/psql -h 'localhost' -p 5432 -U postgres -c "CREATE DATABASE mydatabase"

restore the backup.

/opt/PostgreSQL/9.1/bin/pg_restore --host 'localhost' --port 5432 --username "postgres" --dbname "mydatabase" --no-password --clean "/home/dinesh/db/mydb.backup"

jwt check if token expired

You should use jwt.verify it will check if the token is expired. jwt.decode should not be used if the source is not trusted as it doesn't check if the token is valid.

How do I get the name of the rows from the index of a data frame?


  • outputs the row names as pandas Index object.


  • casts to a list.

df.index['Row 2':'Row 5']

  • supports label slicing similar to columns.

onMeasure custom view explanation

If you don't need to change something onMeasure - there's absolutely no need for you to override it.

Devunwired code (the selected and most voted answer here) is almost identical to what the SDK implementation already does for you (and I checked - it had done that since 2009).

You can check the onMeasure method here :

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
            getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));

public static int getDefaultSize(int size, int measureSpec) {
    int result = size;
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);

    switch (specMode) {
    case MeasureSpec.UNSPECIFIED:
        result = size;
    case MeasureSpec.AT_MOST:
    case MeasureSpec.EXACTLY:
        result = specSize;
    return result;

Overriding SDK code to be replaced with the exact same code makes no sense.

This official doc's piece that claims "the default onMeasure() will always set a size of 100x100" - is wrong.

WebDriverException: unknown error: DevToolsActivePort file doesn't exist while trying to initiate Chrome Browser

Thumb rule

A common cause for Chrome to crash during startup is running Chrome as root user (administrator) on Linux. While it is possible to work around this issue by passing --no-sandbox flag when creating your WebDriver session, such a configuration is unsupported and highly discouraged. You need to configure your environment to run Chrome as a regular user instead.

This error message...

org.openqa.selenium.WebDriverException: unknown error: DevToolsActivePort file doesn't exist 

...implies that the ChromeDriver was unable to initiate/spawn a new WebBrowser i.e. Chrome Browser session.

Your code trials and the versioning information of all the binaries would have given us some hint about what's going wrong.

However as per Add --disable-dev-shm-usage to default launch flags seems adding the argument --disable-dev-shm-usage will temporary solve the issue.

If you desire to initiate/span a new Chrome Browser session you can use the following solution:

System.setProperty("", "C:\\path\\to\\chromedriver.exe");
ChromeOptions options = new ChromeOptions();
options.addArguments("start-maximized"); // open Browser in maximized mode
options.addArguments("disable-infobars"); // disabling infobars
options.addArguments("--disable-extensions"); // disabling extensions
options.addArguments("--disable-gpu"); // applicable to windows os only
options.addArguments("--disable-dev-shm-usage"); // overcome limited resource problems
options.addArguments("--no-sandbox"); // Bypass OS security model
WebDriver driver = new ChromeDriver(options);


As per disable-dev-shm-usage seems to be valid only on Linux OS:

#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
// The /dev/shm partition is too small in certain VM environments, causing
// Chrome to fail or crash (see Use this flag to
// work-around this issue (a temporary directory will always be used to create
// anonymous shared memory files).
const char kDisableDevShmUsage[] = "disable-dev-shm-usage";

In the discussion Add an option to use /tmp instead of /dev/shm David mentions:

I think it would depend on how are /dev/shm and /tmp mounted. If they are both mounted as tmpfs I'm assuming there won't be any difference. if for some reason /tmp is not mapped as tmpfs (and I think is mapped as tmpfs by default by systemd), chrome shared memory management always maps files into memory when creating an anonymous shared files, so even in that case shouldn't be much difference. I guess you could force telemetry tests with the flag enabled and see how it goes.

As for why not use by default, it was a pushed back by the shared memory team, I guess it makes sense it should be useing /dev/shm for shared memory by default.

Ultimately all this should be moving to use memfd_create, but I don't think that's going to happen any time soon, since it will require refactoring Chrome memory management significantly.


You can find a couple of detailed discussions in:


Here is the link to the Sandbox story.

How to update Xcode from command line

Xcode::Install is a simple cli software that allow you to install/select a specific Xcode version.

You can install it using gem install xcode-install
Then you will be able to install a specific version with xcversion install 9.4.1
And if you have more than one version installed, you can switch version with xcversion select 9.4

You can find more information at


There is a version conflict between jar/dependency please check all version of spring is same. if you use maven remove version of dependency and use handle version conflict. Add this in your pom


Double Iteration in List Comprehension

Additionally, you could use just the same variable for the member of the input list which is currently accessed and for the element inside this member. However, this might even make it more (list) incomprehensible.

input = [[1, 2], [3, 4]]
[x for x in input for x in x]

First for x in input is evaluated, leading to one member list of the input, then, Python walks through the second part for x in x during which the x-value is overwritten by the current element it is accessing, then the first x defines what we want to return.

In Jinja2, how do you test if a variable is undefined?

Consider using default filter if it is what you need. For example:

{% set host = | default( -%}

or use more fallback values with "hardcoded" one at the end like:

{% set connectTimeout = config.stackowerflow.connect.timeout | default(config.stackowerflow.timeout) | default(config.timeout) | default(42) -%}

jQuery select2 get value of select tag?

$(".element").select2(/*Your code*/)
.on('change', function (e) {
     var getID = $(this).select2('data');
     alert(getID[0]['id']); // That's the selected ID :)

Unix - copy contents of one directory to another

Quite simple, with a * wildcard.

cp -r Folder1/* Folder2/

But according to your example recursion is not needed so the following will suffice:

cp Folder1/* Folder2/


Or skip the mkdir Folder2 part and just run:

cp -r Folder1 Folder2

What are static factory methods?

I thought i will add some light to this post on what i know. We used this technique extensively in our recent android project. Instead of creating objects using new operator you can also use static method to instantiate a class. Code listing:

//instantiating a class using constructor
Vinoth vin = new Vinoth(); 

//instantiating the class using static method
Class Vinoth{
  private Vinoth(){
  // factory method to instantiate the class
  public static Vinoth getInstance(){
        return new Vinoth();

Static methods support conditional object creation: Each time you invoke a constructor an object will get created but you might not want that. suppose you want to check some condition only then you want to create a new object.You would not be creating a new instance of Vinoth each time, unless your condition is satisfied.

Another example taken from Effective Java.

public static Boolean valueOf(boolean b) {
        return (b ? TRUE : FALSE);

This method translates a boolean primitive value into a Boolean object reference. The Boolean.valueOf(boolean) method illustrates us, it never creates an object. The ability of static factory methods to return the same object from repeated invocations allows classes to maintain strict control over what instances exist at any time.

Static factory methods is that, unlike constructors, they can return an object of any subtype of their return type. One application of this flexibility is that an API can return objects without making their classes public. Hiding implementation classes in this fashion leads to a very compact API.

Calendar.getInstance() is a great example for the above, It creates depending on the locale a BuddhistCalendar, JapaneseImperialCalendar or by default one Georgian.

Another example which i could think is Singleton pattern, where you make your constructors private create an own getInstance method where you make sure, that there is always just one instance available.

public class Singleton{
    //initailzed during class loading
    private static final Singleton INSTANCE = new Singleton();

    //to prevent creating another instance of Singleton
    private Singleton(){}

    public static Singleton getSingleton(){
        return INSTANCE;

Checking if date is weekend PHP

If you're using PHP 5.5 or PHP 7 above, you may want to use:

function isTodayWeekend() {
    return in_array(date("l"), ["Saturday", "Sunday"]);

and it will return "true" if today is weekend and "false" if not.

Sending and Receiving SMS and MMS in Android (pre Kit Kat Android 4.4)

To send an mms for Android 4.0 api 14 or higher without permission to write apn settings, you can use this library: Retrieve mnc and mcc codes from android, then call

Carrier c = Carrier.getCarrier(mcc, mnc);
if (c != null) {
    APN a = c.getAPN();
    if (a != null) {
        String mmsc = a.mmsc;
        String mmsproxy = a.proxy; //"" if none
        int mmsport = a.port; //0 if none

To use this, add Jsoup and droid prism jar to the build path, and import com.droidprism.*;

How to convert Windows end of line in Unix end of line (CR/LF to LF)

sed cannot match \n because the trailing newline is removed before the line is put into the pattern space but can match \r, so you can convert \r\n (dos) to \n (unix) by removing \r

sed -i 's/\r//g' file

Warning: this will change the original file

However, you cannot change from unix EOL to dos or old mac (\r) by this. More readings here:

How can I replace a newline (\n) using sed?

Converting a Date object to a calendar object

Here's your method:

public static Calendar toCalendar(Date date){ 
  Calendar cal = Calendar.getInstance();
  return cal;

Everything else you are doing is both wrong and unnecessary.

BTW, Java Naming conventions suggest that method names start with a lower case letter, so it should be: dateToCalendar or toCalendar (as shown).

OK, let's milk your code, shall we?

DateFormat formatter = new SimpleDateFormat("yyyyMMdd");
date = (Date)formatter.parse(date.toString()); 

DateFormat is used to convert Strings to Dates (parse()) or Dates to Strings (format()). You are using it to parse the String representation of a Date back to a Date. This can't be right, can it?

What is syntax for selector in CSS for next element?

You can use the sibling selector ~:

h1.hc-reform ~ p{

This selects all the p elements that come after .hc-reform, not just the first one.

Reverting to a specific commit based on commit id with Git?

I think, bwawok's answer is wrong at some point:

if you do

git reset --soft c14809fa

It will make your local files changed to be like they were then, but leave your history etc. the same.

According to manual: git-reset, "git reset --soft"...

does not touch the index file nor the working tree at all (but resets the head to <commit>, just like all modes do). This leaves all your changed files "Changes to be committed", as git status would put it.

So it will "remove" newer commits from the branch. This means, after looking at your old code, you cannot go to the newest commit in this branch again, easily. So it does the opposide as described by bwawok: Local files are not changed (they look exactly as before "git reset --soft"), but the history is modified (branch is truncated after the specified commit).

The command for bwawok's answer might be:

git checkout <commit>

You can use this to peek at old revision: How did my code look yesterday?

(I know, I should put this in comments to this answer, but stackoverflow does not allow me to do so! My reputation is too low.)

how to change any data type into a string in python

Just use str - for example:

>>> str([])

How to resolve "gpg: command not found" error during RVM installation?

GnuPG (with binary name gpg) is an application used for public key encryption using the OpenPGP protocol, but also verification of signatures (cryptographic signatures, that also can validate the publisher if used correctly). To some extend, you could say it's for OpenPGP what OpenSSL is for X.509 and TLS.

Unlike most Linux distributions (which make heavy use of GnuPG for ensuring untampered software within their package repositories), Mac OS X does not bring GnuPG with the operating system, so you have to install it on your own.

Possible sources are:

  • Package manager Homebrew: brew install gnupg gnupg2
  • Package manager MacPorts: sudo port install gnupg gnupg2
  • Install from GPGTools, which also brings GUI applications and integration in Apple Mail

How to play YouTube video in my Android application?

Google has a YouTube Android Player API that enables you to incorporate video playback functionality into your Android applications. The API itself is very easy to use and works well. For example, here is how to create a new activity to play a video using the API.

Intent intent = YouTubeStandalonePlayer.createVideoIntent(this, "<<YOUTUBE_API_KEY>>", "<<Youtube Video ID>>", 0, true, false);   

See this for more details.

android layout with visibility GONE

Done by having it like that:

view = inflater.inflate(R.layout.entry_detail, container, false);
TextView tp1= (TextView) view.findViewById(;
LinearLayout layone= (LinearLayout) view.findViewById(;

Python: avoiding pylint warnings about too many arguments

Perhaps you could turn some of the arguments into member variables. If you need that much state a class sounds like a good idea to me.

How to COUNT rows within EntityFramework without loading contents?

I think you want something like

var count = context.MyTable.Count(t => t.MyContainer.ID == '1');

(edited to reflect comments)

"The given path's format is not supported."

Image img = Image.FromFile(System.IO.Path.GetFullPath("C:\\ File Address"));

you need getfullpath by pointed class. I had same error and fixed...

LINQ to SQL - How to select specific columns and return strongly typed list

Basically you are doing it the right way. However, you should use an instance of the DataContext for querying (it's not obvious that DataContext is an instance or the type name from your query):

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new Person { Name = a.Name, Age = a.Age }).ToList();

Apparently, the Person class is your LINQ to SQL generated entity class. You should create your own class if you only want some of the columns:

class PersonInformation {
   public string Name {get;set;}
   public int Age {get;set;}

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new PersonInformation { Name = a.Name, Age = a.Age }).ToList();

You can freely swap var with List<PersonInformation> here without affecting anything (as this is what the compiler does).

Otherwise, if you are working locally with the query, I suggest considering an anonymous type:

var result = (from a in new DataContext().Persons
              where a.Age > 18
              select new { a.Name, a.Age }).ToList();

Note that in all of these cases, the result is statically typed (it's type is known at compile time). The latter type is a List of a compiler generated anonymous class similar to the PersonInformation class I wrote above. As of C# 3.0, there's no dynamic typing in the language.


If you really want to return a List<Person> (which might or might not be the best thing to do), you can do this:

var result = from a in new DataContext().Persons
             where a.Age > 18
             select new { a.Name, a.Age };

List<Person> list = result.AsEnumerable()
                          .Select(o => new Person {
                                           Name = o.Name, 
                                           Age = o.Age

You can merge the above statements too, but I separated them for clarity.

Regular vs Context Free Grammars

a regular grammer is never ambiguous because it is either left linear or right linear so we cant make two decision tree for regular grammer so it is always unambiguous.but othert than regular grammar all are may or may not be regular

I want to truncate a text or line with ellipsis using JavaScript

KooiInc has a good answer to this. To summarise:

String.prototype.trunc = 
          return this.substr(0,n-1)+(this.length>n?'&hellip;':'');

Now you can do:

var s = 'not very long';
s.trunc(25); //=> not very long
s.trunc(5); //=> not...

And if you prefer it as a function, as per @AlienLifeForm's comment:

function truncateWithEllipses(text, max) 
    return text.substr(0,max-1)+(text.length>max?'&hellip;':''); 

Full credit goes to KooiInc for this.

How to add Android Support Repository to Android Studio?

I used to get similar issues. Even after installing the support repository, the build used to fail.

Basically the issues is due to the way the version number of the jar files are specified in the gradle files are specified properly.

For example, in my case i had set it as "compile ''"

On removing "+" the build was sucessful!!

How to write :hover using inline style?

Not gonna happen with CSS only

Inline javascript

<a href='index.html' 
    Click Me

In a working draft of the CSS2 spec it was declared that you could use pseudo-classes inline like this:

<a href=""
   style="{color: blue; background: white}  /* a+=0 b+=0 c+=0 */
      :visited {color: green}           /* a+=0 b+=1 c+=0 */
      :hover {background: yellow}       /* a+=0 b+=1 c+=0 */
      :visited:hover {color: purple}    /* a+=0 b+=2 c+=0 */

but it was never implemented in the release of the spec as far as I know.

ExecutorService, how to wait for all tasks to finish

Add all threads in collection and submit it using invokeAll. If you can use invokeAll method of ExecutorService, JVM won’t proceed to next line until all threads are complete.

Here there is a good example: invokeAll via ExecutorService

Easiest way to convert a Blob into a byte array

The easiest way is this.

byte[] bytes = rs.getBytes("my_field");

Multiple models in a view

My advice is to make a big view model:

public BigViewModel
    public LoginViewModel LoginViewModel{get; set;}
    public RegisterViewModel RegisterViewModel {get; set;}

In your Index.cshtml, if for example you have 2 partials:

@addTagHelper *,Microsoft.AspNetCore.Mvc.TagHelpers
@model .BigViewModel

@await Html.PartialAsync("_LoginViewPartial", Model.LoginViewModel)

@await Html.PartialAsync("_RegisterViewPartial ", Model.RegisterViewModel )

and in controller:

model=new BigViewModel();
model.LoginViewModel=new LoginViewModel();
model.RegisterViewModel=new RegisterViewModel(); 

jQuery Ajax File Upload

To get all your form inputs, including the type="file" you need to use FormData object. you will be able to see the formData content in the debugger -> network ->Headers after you will submit the form.

var url = "YOUR_URL";

var form = $('#YOUR_FORM_ID')[0];
var formData = new FormData(form);

$.ajax(url, {
    method: 'post',
    processData: false,
    contentType: false,
    data: formData
    if (data.success){ 
        alert("Files uploaded");
    } else {
        alert("Error while uploading the files");
    alert("Error while uploading the files");

Measuring function execution time in R

There is also proc.time()

You can use in the same way as Sys.time but it gives you a similar result to system.time.

ptm <- proc.time()
#your function here
proc.time() - ptm

the main difference between using

system.time({ #your function here })

is that the proc.time() method still does execute your function instead of just measuring the time... and by the way, I like to use system.time with {} inside so you can put a set of things...

How do I pass a datetime value as a URI parameter in mvc?

Typical format of a URI for ASP .NET MVC is Controller/Action/Id where Id is an integer

I would suggest sending the date value as a parameter rather than as part of the route:

 mysite/Controller/Action?date=21-9-2009 10:20

If it's still giving you problems the date may contain characters that are not allowed in a URI and need to be encoded. Check out:


It is a method within Javascript.

On the Server Side:

public ActionResult ActionName(string date)
     DateTime mydate;
     DateTime.Tryparse(date, out mydate);

FYI, any url parameter can be mapped to an action method parameter as long as the names are the same.

Create WordPress Page that redirects to another URL

Use the "raw" plugin Then it's as simple as:

window.location = "";

Python - abs vs fabs

math.fabs() converts its argument to float if it can (if it can't, it throws an exception). It then takes the absolute value, and returns the result as a float.

In addition to floats, abs() also works with integers and complex numbers. Its return type depends on the type of its argument.

In [7]: type(abs(-2))
Out[7]: int

In [8]: type(abs(-2.0))
Out[8]: float

In [9]: type(abs(3+4j))
Out[9]: float

In [10]: type(math.fabs(-2))
Out[10]: float

In [11]: type(math.fabs(-2.0))
Out[11]: float

In [12]: type(math.fabs(3+4j))
TypeError                                 Traceback (most recent call last)
/home/npe/<ipython-input-12-8368761369da> in <module>()
----> 1 type(math.fabs(3+4j))

TypeError: can't convert complex to float

How can I dynamically set the position of view in Android?

One thing to keep in mind with positioning is that each view has an index relative to its parent view. So if you have a linear layout with three subviews, the subviews will each have an index: 0, 1, 2 in the above case.

This allows you to add a view to the last position (or the end) in a parent view by doing something like this:

int childCount = parent.getChildCount();
parentView.addView(newView, childCount);

Alternatively you could replace a view using something like the following:

int childIndex = parentView.indexOfChild(childView);

parentView.addView(newView, childIndex);

How to Retrieve value from JTextField in Java Swing?

How do we retrieve a value from a text field?


ActionListner example:


public void actionPerformed(ActionEvent evt) {
    String text = textField.getText();
    textArea.append(text + newline);

Best ways to teach a beginner to program?

"Who's Afraid of C++" By Heller

Might be worth a shot

CodeIgniter: How To Do a Select (Distinct Fieldname) MySQL Query

Simple but usefull way:

$query = $this->db->distinct()->select('order_id')->get_where('tbl_order_details', array('seller_id' => $seller_id));
        return $query;

Case insensitive comparison NSString

Try this method

- (NSComparisonResult)caseInsensitiveCompare:(NSString *)aString

"cannot be used as a function error"

#include "header.h"

int estimatedPopulation (int currentPopulation, float growthRate)
    return currentPopulation + currentPopulation * growthRate  / 100;

Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM

Here's some working C++ code which solves the problem.

Proof that the memory constraints are satisfied:

Editor: There is no proof of the maximum memory requirements offered by the author either in this post or in his blogs. Since the number of bits necessary to encode a value depends on the values previously encoded, such a proof is likely non-trivial. The author notes that the largest encoded size he could stumble upon empirically was 1011732, and chose the buffer size 1013000 arbitrarily.

typedef unsigned int u32;

namespace WorkArea
    static const u32 circularSize = 253250;
    u32 circular[circularSize] = { 0 };         // consumes 1013000 bytes

    static const u32 stageSize = 8000;
    u32 stage[stageSize];                       // consumes 32000 bytes


Together, these two arrays take 1045000 bytes of storage. That leaves 1048576 - 1045000 - 2×1024 = 1528 bytes for remaining variables and stack space.

It runs in about 23 seconds on my Xeon W3520. You can verify that the program works using the following Python script, assuming a program name of sort1mb.exe.

from subprocess import *
import random

sequence = [random.randint(0, 99999999) for i in xrange(1000000)]

sorter = Popen('sort1mb.exe', stdin=PIPE, stdout=PIPE)
for value in sequence:
    sorter.stdin.write('%08d\n' % value)

result = [int(line) for line in sorter.stdout]
print('OK!' if result == sorted(sequence) else 'Error!')

A detailed explanation of the algorithm can be found in the following series of posts:

Making a PowerShell POST request if a body param starts with '@'

@Frode F. gave the right answer.

By the Way Invoke-WebRequest also prints you the 200 OK and a lot of bla, bla, bla... which might be useful but I still prefer the Invoke-RestMethod which is lighter.

Also, keep in mind that you need to use | ConvertTo-Json for the body only, not the header:

$body = @{
 "OptionalEmail"="[email protected]"
} | ConvertTo-Json

$header = @{

Invoke-RestMethod -Uri "http://MyServer/WSVistaWebClient/RESTService.svc/member/search" -Method 'Post' -Body $body -Headers $header | ConvertTo-HTML

and you can then append a | ConvertTo-HTML at the end of the request for better readability

Android Studio and cannot resolve symbol


I have already had the following dependency in my build.gradle

implementation ''

I have tried all of the following,

  • Invalidate Caches/Restart
  • Sync project with gradle files
  • Clean project
  • Rebuild project
  • gradlew clean

But, none of them worked for me.


Finally, I solved it by deleting "/.idea/libraries", and then synced with gradle and built again.

Font awesome is not showing icon

First, check that you have class="fa" as well as whatever the icon's class is. So, not just

<i class="fa-pencil" title="Edit"></i>

But also

<i class="fa fa-pencil" title="Edit"></i> 

Then it works as expected. This solved my issue.

How to get names of classes inside a jar file?

Unfortunately, Java doesn't provide an easy way to list classes in the "native" JRE. That leaves you with a couple of options: (a) for any given JAR file, you can list the entries inside that JAR file, find the .class files, and then determine which Java class each .class file represents; or (b) you can use a library that does this for you.

Option (a): Scanning JAR files manually

In this option, we'll fill classNames with the list of all Java classes contained inside a jar file at /path/to/jar/file.jar.

List<String> classNames = new ArrayList<String>();
ZipInputStream zip = new ZipInputStream(new FileInputStream("/path/to/jar/file.jar"));
for (ZipEntry entry = zip.getNextEntry(); entry != null; entry = zip.getNextEntry()) {
    if (!entry.isDirectory() && entry.getName().endsWith(".class")) {
        // This ZipEntry represents a class. Now, what class does it represent?
        String className = entry.getName().replace('/', '.'); // including ".class"
        classNames.add(className.substring(0, className.length() - ".class".length()));

Option (b): Using specialized reflections libraries


Guava has had ClassPath since at least 14.0, which I have used and liked. One nice thing about ClassPath is that it doesn't load the classes it finds, which is important when you're scanning for a large number of classes.

ClassPath cp=ClassPath.from(Thread.currentThread().getContextClassLoader());
for(ClassPath.ClassInfo info : cp.getTopLevelClassesRecurusive("")) {
    // Do stuff with classes here...


I haven't personally used the Reflections library, but it seems well-liked. Some great examples are provided on the website like this quick way to load all the classes in a package provided by any JAR file, which may also be useful for your application.

Reflections reflections = new Reflections("my.project.prefix");

Set<Class<? extends SomeType>> subTypes = reflections.getSubTypesOf(SomeType.class);

Set<Class<?>> annotated = reflections.getTypesAnnotatedWith(SomeAnnotation.class);

How to pass a type as a method parameter in Java

You can pass an instance of java.lang.Class that represents the type, i.e.

private void foo(Class cls)

Detect & Record Audio in Python

Thanks to cryo for improved version that I based my tested code below:

#Instead of adding silence at start and end of recording (values=0) I add the original audio . This makes audio sound more natural as volume is >0. See trim()
#I also fixed issue with the previous code - accumulated silence counter needs to be cleared once recording is resumed.

from array import array
from struct import pack
from sys import byteorder
import copy
import pyaudio
import wave

THRESHOLD = 500  # audio levels not normalised.
SILENT_CHUNKS = 3 * 44100 / 1024  # about 3sec
FORMAT = pyaudio.paInt16
FRAME_MAX_VALUE = 2 ** 15 - 1
NORMALIZE_MINUS_ONE_dB = 10 ** (-1.0 / 20)
RATE = 44100

def is_silent(data_chunk):
    """Returns 'True' if below the 'silent' threshold"""
    return max(data_chunk) < THRESHOLD

def normalize(data_all):
    """Amplify the volume out to max -1dB"""
    # MAXIMUM = 16384
    normalize_factor = (float(NORMALIZE_MINUS_ONE_dB * FRAME_MAX_VALUE)
                        / max(abs(i) for i in data_all))

    r = array('h')
    for i in data_all:
        r.append(int(i * normalize_factor))
    return r

def trim(data_all):
    _from = 0
    _to = len(data_all) - 1
    for i, b in enumerate(data_all):
        if abs(b) > THRESHOLD:
            _from = max(0, i - TRIM_APPEND)

    for i, b in enumerate(reversed(data_all)):
        if abs(b) > THRESHOLD:
            _to = min(len(data_all) - 1, len(data_all) - 1 - i + TRIM_APPEND)

    return copy.deepcopy(data_all[_from:(_to + 1)])

def record():
    """Record a word or words from the microphone and 
    return the data as an array of signed shorts."""

    p = pyaudio.PyAudio()
    stream =, channels=CHANNELS, rate=RATE, input=True, output=True, frames_per_buffer=CHUNK_SIZE)

    silent_chunks = 0
    audio_started = False
    data_all = array('h')

    while True:
        # little endian, signed short
        data_chunk = array('h',
        if byteorder == 'big':

        silent = is_silent(data_chunk)

        if audio_started:
            if silent:
                silent_chunks += 1
                if silent_chunks > SILENT_CHUNKS:
                silent_chunks = 0
        elif not silent:
            audio_started = True              

    sample_width = p.get_sample_size(FORMAT)

    data_all = trim(data_all)  # we trim before normalize as threshhold applies to un-normalized wave (as well as is_silent() function)
    data_all = normalize(data_all)
    return sample_width, data_all

def record_to_file(path):
    "Records from the microphone and outputs the resulting data to 'path'"
    sample_width, data = record()
    data = pack('<' + ('h' * len(data)), *data)

    wave_file =, 'wb')

if __name__ == '__main__':
    print("Wait in silence to begin recording; wait in silence to terminate")
    print("done - result written to demo.wav")

Error: [$injector:unpr] Unknown provider: $routeProvider

In angular 1.4 +, in addition to adding the dependency

angular.module('myApp', ['ngRoute'])

,we also need to reference the separate angular-route.js file

<script src="angular.js">
<script src="angular-route.js">


How to call a method defined in an AngularJS directive?

You can specify a DOM attribute that can be used to allow the directive to define a function on the parent scope. The parent scope can then call this method like any other. Here's a plunker. And below is the relevant code.

clearfn is an attribute on the directive element into which the parent scope can pass a scope property which the directive can then set to a function that accomplish's the desired behavior.

<!DOCTYPE html>
<html ng-app="myapp">
    <script data-require="angular.js@*" data-semver="1.3.0-beta.5" src=""></script>
    <link rel="stylesheet" href="style.css" />
        border:solid 1px #aaa;
        box-shadow:inset 0px 0px .4em #aaa;
  <body ng-controller="mycontroller">
    <h1>Call method on directive</h1>
    <button ng-click="clear()">Clear</button>
    <my-box clearfn="clear" contentEditable=true></my-box>
      var app = angular.module('myapp', []);
      app.controller('mycontroller', function($scope){
      app.directive('myBox', function(){
        return {
          restrict: 'E',
          scope: {
            clearFn: '=clearfn'
          template: '',
          link: function(scope, element, attrs){
            element.html('Hello World!');
            scope.clearFn = function(){

Automated way to convert XML files to SQL database?

If there is XML file with 2 different tables then will:



How to select distinct query using symfony2 doctrine query builder?

This works:

$category = $catrep->createQueryBuilder('cc')
        ->where('cc.contenttype = :type')
        ->setParameter('type', 'blogarticle')

$categories = $category->getResult();

Edit for Symfony 3 & 4.

You should use ->groupBy('cc.categoryid') instead of ->distinct()

set height of imageview as matchparent programmatically

    (new ViewGroup.MarginLayoutParams
        (width, ViewGroup.LayoutParams.MATCH_PARENT));

The Type of layout params depends on the parent view group. If you put the wrong one it will cause exception.

Jquery : Refresh/Reload the page on clicking a button

Use this line simply inside your head with


It will load your current page or view.

Convert base64 string to ArrayBuffer

For Node.js users:

const myBuffer = Buffer.from(someBase64String, 'base64');

myBuffer will be of type Buffer which is a subclass of Uint8Array. Unfortunately, Uint8Array is NOT an ArrayBuffer as the OP was asking for. But when manipulating an ArrayBuffer I almost always wrap it with Uint8Array or something similar, so it should be close to what's being asked for.

How can I add a class to a DOM element in JavaScript?

This is better way

let new_row = document.createElement('div');
new_row.setAttribute("class", "classname");
new_row.setAttribute("id", "idname");

ImportError: No module named PyQt4.QtCore

As mentioned in the comments, you need to install the python-qt4 package - no need to recompile it yourself.

sudo apt-get install python-qt4

makefiles - compile all c files at once

LIBS  = -lkernel32 -luser32 -lgdi32 -lopengl32
CFLAGS = -Wall

# Should be equivalent to your list of C files, if you don't build selectively
SRC=$(wildcard *.c)

test: $(SRC)
    gcc -o $@ $^ $(CFLAGS) $(LIBS)

Does Java read integers in little endian or big endian?

Use the network byte order (big endian), which is the same as Java uses anyway. See man htons for the different translators in C.

LaTeX table too wide. How to make it fit?

You can use these options as well, either use \footnotesize or \tiny. This would really help in fitting big tables.

\caption{Information on making the table size small}
    S.No       & HMD           \\
    1          & HTC Vive \\
    2          & HTC Vive Pro   \\

How to get a certain element in a list, given the position?

Maybe not the most efficient way. But you could convert the list into a vector.

#include <list>
#include <vector>

list<Object> myList;

vector<Object> myVector(myList.begin(), myList.end());

Then access the vector using the [x] operator.

auto x = MyVector[0];

You could put that in a helper function:

#include <memory>
#include <vector>
#include <list>

template<class T>
ListToVector(list<T> List) {
shared_ptr<vector<T>> Vector {
        new vector<string>(List.begin(), List.end()) }
return Vector;

Then use the helper funciton like this:

auto MyVector = ListToVector(Object);
auto x = MyVector[0];

Free ASP.Net and/or CSS Themes

I wouldn't bother looking for ASP.NET stuff specifically (probably won't find any anyways). Finding a good CSS theme easily can be used in ASP.NET.

Here's some sites that I love for CSS goodness:

iPhone 5 CSS media query

All these answers listed above, that use max-device-width or max-device-height for media queries, suffer from very strong bug: they also target a lot of other popular mobile devices (probably unwanted and never tested, or that will hit the market in future).

This queries will work for any device that has a smaller screen, and probably your design will be broken.

Combined with similar device-specific media queries (for HTC, Samsung, IPod, Nexus...) this practice will launch a time-bomb. For debigging, this idea can make your CSS an uncontrolled spagetti. You can never test all possible devices.

Please be aware that the only media query always targeting IPhone5 and nothing else, is:

/* iPhone 5 Retina regardless of IOS version */
@media (device-height : 568px) 
   and (device-width : 320px) 
   and (-webkit-min-device-pixel-ratio: 2)
/* and (orientation : todo: you can add orientation or delete this comment)*/ {
                 /*IPhone 5 only CSS here*/

Note that exact width and height, not max-width is checked here.

Now, what is the solution? If you want to write a webpage that will look good on all possible devices, the best practice is to you use degradation

/* degradation pattern we are checking screen width only sure, this will change is turning from portrait to landscape*/

/*css for desktops here*/

@media (max-device-width: 1024px) {
  /*IPad portrait AND netbooks, AND anything with smaller screen*/
  /*make the design flexible if possible */
  /*Structure your code thinking about all devices that go below*/
@media (max-device-width: 640px) {
 /*Iphone portrait and smaller*/
@media (max-device-width: 540px) {
 /*Smaller and smaller...*/
@media (max-device-width: 320px) {
 /*IPhone portrait and smaller. You can probably stop on 320px*/

If more than 30% of your website visitors come from mobile, turn this scheme upside-down, providing mobile-first approach. Use min-device-width in that case. This will speed up webpage rendering for mobile browsers.

jQuery UI: Datepicker set year range dropdown to 100 years

You can set the year range using this option in jQuery UI datepicker:

yearRange: "c-100:c+0", // last hundred years and current years

yearRange: "c-100:c+100", // last hundred years and future hundred years

yearRange: "c-10:c+10", // last ten years and future ten years

Android check permission for LocationManager

Use my custome class to check or request permisson

public class Permissons {

        //Request Permisson
        public static void Request_STORAGE(Activity act,int code)

            ActivityCompat.requestPermissions(act, new
        public static void Request_CAMERA(Activity act,int code)
            ActivityCompat.requestPermissions(act, new
        public static void Request_FINE_LOCATION(Activity act,int code)
            ActivityCompat.requestPermissions(act, new
        public static void Request_READ_SMS(Activity act,int code)
            ActivityCompat.requestPermissions(act, new
        public static void Request_READ_CONTACTS(Activity act,int code)
            ActivityCompat.requestPermissions(act, new
        public static void Request_READ_CALENDAR(Activity act,int code)
            ActivityCompat.requestPermissions(act, new
        public static void Request_RECORD_AUDIO(Activity act,int code)
            ActivityCompat.requestPermissions(act, new

        //Check Permisson
        public static boolean Check_STORAGE(Activity act)
            int result = ContextCompat.checkSelfPermission(act,android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_CAMERA(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.CAMERA);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_FINE_LOCATION(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.ACCESS_FINE_LOCATION);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_READ_SMS(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.READ_SMS);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_READ_CONTACTS(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.READ_CONTACTS);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_READ_CALENDAR(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.READ_CALENDAR);
            return result == PackageManager.PERMISSION_GRANTED;
        public static boolean Check_RECORD_AUDIO(Activity act)
            int result = ContextCompat.checkSelfPermission(act, Manifest.permission.RECORD_AUDIO);
            return result == PackageManager.PERMISSION_GRANTED;


   //if not permisson granted so request permisson with request code

How to do this in Laravel, subquery where in

Consider this code:

Products::whereIn('id', function($query){
    ->from(with(new ProductCategory)->getTable())
    ->whereIn('category_id', ['223', '15'])
    ->where('active', 1);

Removing the fragment identifier from AngularJS urls (# symbol)

This answer assumes that you are using nginx as reverse proxy and you already did set $locationProvider.html5mode to true.

->For the people who might still be struggling with all cool stuff above.

Surely, @maxim grach solution works fine, but for the solution for how to respond to requests that doesn't want the hashtag to be included in the first place what can be done is check if php is sending 404 and then rewrite the url. Following is the code for nginx,

In the php location, detect 404 php error and redirect to another location,

location ~ \.php${
  fastcgi_intercept_errors on;
  error_page 404 = /redirect/$request_uri ;

Then rewrite url in redirect location and proxy_pass the data, offcourse, put your website url at the place of my blog's url. (Request : Question this only after you tried it)

location /redirect {
  rewrite ^/redirect/(.*) /$1;

And see the magic.

And it definitely works, atleast for me.

Simple working Example of in

Imports Newtonsoft.Json.Linq

Dim json As JObject = JObject.Parse(Me.TextBox1.Text)

Example JavaScript code to parse CSV data


It's a jQuery plugin designed to work as an end-to-end solution for parsing CSV into JavaScript data. It handles every single edge case presented in RFC 4180, as well as some that pop up for Excel/Google spreadsheet exports (i.e., mostly involving null values) that the specification is missing.



Dangerous,'Busta Rhymes','When Disaster Strikes',1997

// Calling this
music = $.csv.toArrays(csv)

// Outputs...
  ["track", "artist", "album", "year"],
  ["Dangerous", "Busta Rhymes", "When Disaster Strikes", "1997"]

console.log(music[1][2]) // Outputs: 'When Disaster Strikes'


Oh yeah, I should also probably mention that it's completely configurable.

music = $.csv.toArrays(csv, {
  delimiter: "'", // Sets a custom value delimiter character
  separator: ';', // Sets a custom field separator character

Update 2:

It now works with jQuery on Node.js too. So you have the option of doing either client-side or server-side parsing with the same library.

Update 3:

Since the Google Code shutdown, jquery-csv has been migrated to GitHub.

Disclaimer: I am also the author of jQuery-CSV.

Pyspark: display a spark data frame in a table format

Let's say we have the following Spark DataFrame:

df = sqlContext.createDataFrame(
        (1, "Mark", "Brown"), 
        (2, "Tom", "Anderson"), 
        (3, "Joshua", "Peterson")
    ('id', 'firstName', 'lastName')

There are typically three different ways you can use to print the content of the dataframe:

Print Spark DataFrame

The most common way is to use show() function:

| id|firstName|lastName|
|  1|     Mark|   Brown|
|  2|      Tom|Anderson|
|  3|   Joshua|Peterson|

Print Spark DataFrame vertically

Say that you have a fairly large number of columns and your dataframe doesn't fit in the screen. You can print the rows vertically - For example, the following command will print the top two rows, vertically, without any truncation.

>>>, truncate=False, vertical=True)
-RECORD 0-------------
 id        | 1        
 firstName | Mark     
 lastName  | Brown    
-RECORD 1-------------
 id        | 2        
 firstName | Tom      
 lastName  | Anderson 
only showing top 2 rows

Convert to Pandas and print Pandas DataFrame

Alternatively, you can convert your Spark DataFrame into a Pandas DataFrame using .toPandas() and finally print() it.

>>> df_pd = df.toPandas()
>>> print(df_pd)
   id firstName  lastName
0   1      Mark     Brown
1   2       Tom  Anderson
2   3    Joshua  Peterson

Note that this is not recommended when you have to deal with fairly large dataframes, as Pandas needs to load all the data into memory. If this is the case, the following configuration will help when converting a large spark dataframe to a pandas one:

spark.conf.set("spark.sql.execution.arrow.pyspark.enabled", "true")

For more details you can refer to my blog post Speeding up the conversion between PySpark and Pandas DataFrames

Node.js: How to read a stream into a buffer?

in ts, [].push(bufferPart) is not compatible;


getBufferFromStream(stream: Part | null): Promise<Buffer> {
    if (!stream) {
        throw 'FILE_STREAM_EMPTY';
    return new Promise(
        (r, j) => {
            let buffer = Buffer.from([]);
            stream.on('data', buf => {
               buffer = Buffer.concat([buffer, buf]);
            stream.on('end', () => r(buffer));
            stream.on('error', j);

Place cursor at the end of text in EditText

This works

Editable etext = edittext.getText();

TypeScript getting error TS2304: cannot find name ' require'

Make sure you have installed npm i @types/node

how to remove only one style property with jquery

The documentation for css() says that setting the style property to the empty string will remove that property if it does not reside in a stylesheet:

Setting the value of a style property to an empty string — e.g. $('#mydiv').css('color', '') — removes that property from an element if it has already been directly applied, whether in the HTML style attribute, through jQuery's .css() method, or through direct DOM manipulation of the style property. It does not, however, remove a style that has been applied with a CSS rule in a stylesheet or <style> element.

Since your styles are inline, you can write:

$(selector).css("-moz-user-select", "");

How do I detect unsigned integer multiply overflow?

For unsigned integers, just check that the result is smaller than one of the arguments:

unsigned int r, a, b;
r = a + b;
if (r < a)
    // Overflow

For signed integers you can check the signs of the arguments and of the result.

Integers of different signs can't overflow, and integers of the same sign overflow only if the result is of a different sign:

signed int r, a, b, s;
r = a + b;
s = a>=0;
if (s == (b>=0) && s != (r>=0))
    // Overflow

set option "selected" attribute from dynamic created option

To set the input option at run time try setting the 'checked' value. (even if it isn't a checkbox)


Where elem is a reference to the option to be selected.

So for the above issue:

var country = document.getElementById("country");

This works for me, even when the options are not wrapped in a .

If all of the tags share the same name, they should uncheck when the new one is checked.


Use SELECT CONVERT(date, '20140327')

In your case,

       CONVERT(date, [GRADUATION_DATE])     
FROM mydb

Combining C++ and C - how does #ifdef __cplusplus work?

A couple of gotchas that are colloraries to Andrew Shelansky's excellent answer and to disagree a little with doesn't really change the way that the compiler reads the code

Because your function prototypes are compiled as C, you can't have overloading of the same function names with different parameters - that's one of the key features of the name mangling of the compiler. It is described as a linkage issue but that is not quite true - you will get errors from both the compiler and the linker.

The compiler errors will be if you try to use C++ features of prototype declaration such as overloading.

The linker errors will occur later because your function will appear to not be found, if you do not have the extern "C" wrapper around declarations and the header is included in a mixture of C and C++ source.

One reason to discourage people from using the compile C as C++ setting is because this means their source code is no longer portable. That setting is a project setting and so if a .c file is dropped into another project, it will not be compiled as c++. I would rather people take the time to rename file suffixes to .cpp.

Kotlin - Property initialization using "by lazy" vs. "lateinit"

If you use an unchangable variable, then it is better to initialize with by lazy { ... } or val. In this case you can be sure that it will always be initialized when needed and at most 1 time.

If you want a non-null variable, that can change it's value, use lateinit var. In Android development you can later initialize it in such events like onCreate, onResume. Be aware, that if you call REST request and access this variable, it may lead to an exception UninitializedPropertyAccessException: lateinit property yourVariable has not been initialized, because the request can execute faster than that variable could initialize.

How do I make the text box bigger in HTML/CSS?

According to this answer, here is what it says:

In Javascript, you can manipulate DOM CSS properties, for example:


If you simply want to specify the height and font size, use CSS or style attributes, e.g.

//in your CSS file or <style> tag

<!--in your HTML-->
<input id="textboxid" ...>


<input style="height:200px;font-size:14pt;" .....>

PHP Array to JSON Array using json_encode();

I had a problem with accented characters when converting a PHP array to JSON. I put UTF-8 stuff all over the place but nothing solved my problem until I added this piece of code in my PHP while loop where I was pushing the array:

$es_words[] = array(utf8_encode("$word"),"$alpha","$audio");

It was only the '$word' variable that was giving a problem. Afterwards it did a jason_encode no problem.

Hope that helps

HTML <sup /> tag affecting line height, how to make it consistent?

I prefer to use length on the vertical-align. This aligns the baseline of the element at the given length above the baseline of its parent.

sup {
   font-size: .83em;
   vertical-align: 0.25em;
   line-height: 0;

How to set Java classpath in Linux?

export CLASSPATH=/home/appnetix/LOG4J_HOME/log4j-1.2.16.jar

or, if you already have some classpath set

export CLASSPATH=$CLASSPATH:/home/appnetix/LOG4J_HOME/log4j-1.2.16.jar

and, if also you want to include current directory

export CLASSPATH=$CLASSPATH:/home/appnetix/LOG4J_HOME/log4j-1.2.16.jar:.

How to describe table in SQL Server 2008?

I like the answer that attempts to do the translate, however, while using the code it doesn't like columns that are not VARCHAR type such as BIGINT or DATETIME. I needed something similar today so I took the time to modify it more to my liking. It is also now encapsulated in a function which is the closest thing I could find to just typing describe as oracle handles it. I may still be missing a few data types in my case statement but this works for everything I tried it on. It also orders by ordinal position. this could be expanded on to include primary key columns easily as well.

CREATE FUNCTION dbo.describe (@TABLENAME varchar(50))
returns table
SELECT TOP 1000 column_name AS [ColumnName],
       IS_NULLABLE AS [IsNullable],
       DATA_TYPE + '(' + CASE 
                                    WHEN DATA_TYPE = 'varchar' or DATA_TYPE = 'char' THEN 
                                        WHEN Cast(CHARACTER_MAXIMUM_LENGTH AS VARCHAR(5)) = -1 THEN 'Max'
                                        ELSE Cast(CHARACTER_MAXIMUM_LENGTH AS VARCHAR(5))
                                    WHEN DATA_TYPE = 'decimal' or DATA_TYPE = 'numeric' THEN
                                      Cast(NUMERIC_PRECISION AS VARCHAR(5))+', '+Cast(NUMERIC_SCALE AS VARCHAR(5))
                                    WHEN DATA_TYPE = 'bigint' or DATA_TYPE = 'int' THEN
                                      Cast(NUMERIC_PRECISION AS VARCHAR(5))
                                    ELSE ''
                                  END + ')' AS [DataType]
WHERE  table_name = @TABLENAME
order by ordinal_Position

once you create the function here is a sample table that I used

create table dbo.yourtable
(columna bigint,
 columnb int,
 columnc datetime,
 columnd varchar(100),
 columne char(10),
 columnf bit,
 columng numeric(10,2),
 columnh decimal(10,2)

Then you can execute it as follows

select * from describe ('yourtable')

It returns the following

ColumnName IsNullable DataType

columna NO bigint(19)
columnb NO int(10)
columnc NO datetime()
columnd NO varchar(100)
columne NO char(10)
columnf NO bit()
columng NO numeric(10, 2)
columnh NO decimal(10, 2)

hope this helps someone.

Does svn have a `revert-all` command?

Use the recursive switch --recursive (-R)

svn revert -R .

CSS media query to target only iOS devices

Short answer No. CSS is not specific to brands.

Below are the articles to implement for iOS using media only.

Infact you can use PHP, Javascript to detect the iOS browser and according to that you can call CSS file. For instance

MAC addresses in JavaScript

I concur with all the previous answers that it would be a privacy/security vulnerability if you would be able to do this directly from Javascript. There are two things I can think of:

  • Using Java (with a signed applet)
  • Using signed Javascript, which in FF (and Mozilla in general) gets higher privileges than normal JS (but it is fairly complicated to set up)

How to retrieve images from MySQL database and display in an html tag

add $row = mysql_fetch_object($result); after your mysql_query();

your html <img src="<?php echo $row->dvdimage; ?>" width="175" height="200" />

Killing a process created with Python's subprocess.Popen()

In your code it should be


Both kill or terminate are methods of the Popen object which sends the signal signal.SIGKILL to the process.

Embed a PowerPoint presentation into HTML

I was looking for a solution for similar problem.

I looked into

But they have no better documentation, and even no demo page I could see over there and it was seemingly difficult.

What I came up with is: SkyDrive by Microsoft.

All you need is an account with them and upload your PPT and embed them straightaway. PPT player is quite clean to use and I like it.

How to get current route in Symfony 2?

For anybody that need current route for Symfony 3, this is what I use

   $request = $this->container->get('router.request_context');
   //Assuming you are on user registration page like
   $scheme = $request->getScheme(); //This will return https
   $host = $request->getHost(); // This will return
   $route = $request->getPathInfo(); // This will return user/registration(don't forget this is registrationAction in userController
   $name = $request->get('_route'); // This will return the name.

Network tools that simulate slow network connection

I love Charles.

The free version works fine for me.

Throttling, rerwiting, breakpoints are all awesome features.

What's the best three-way merge tool?

The summary is that I found ECMerge to be a great, though commercial product.

enter image description here

I also agree with MrTelly that Ultracompare is very good. One nice feature is that it will compare RTF and Word docs, which is handy when you end up programming in word with the sales guys and they don't manage their docs correctly.

How to compile and run C in sublime text 3?

try to write a shell script named in your project foler


and make a Build System to compile and execute it:

      "shell_cmd": "make all && ./"

don't forget $chmod +x

do one thing and do it well:)

How to trigger a click on a link using jQuery

With the code you provided, you cannot expect anything to happen. I second @mashappslabs : first add an event handler :

$("selector").click(function() {
    console.log("element was clicked"); // or alert("click");

then trigger your event :

$("selector").click(); //or

and you should see the message in your console.

Writing to a file in a for loop

That is because you are opening , writing and closing the file 10 times inside your for loop

myfile = open('xyz.txt', 'w')

You should open and close your file outside for loop.

myfile = open('xyz.txt', 'w')
for line in lines:
    var1, var2 = line.split(",");
    myfile.write("%s\n" % var1)


You should also notice to use write and not writelines.

writelines writes a list of lines to your file.

Also you should check out the answers posted by folks here that uses with statement. That is the elegant way to do file read/write operations in Python

convert epoch time to date

EDIT: Okay, so you don't want your local time (which isn't Australia) to contribute to the result, but instead the Australian time zone. Your existing code should be absolutely fine then, although Sydney is currently UTC+11, not UTC+10.. Short but complete test app:

import java.util.*;
import java.text.*;

public class Test {
    public static void main(String[] args) throws InterruptedException {
        Date date = new Date(1318386508000L);
        DateFormat format = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
        String formatted = format.format(date);
        formatted = format.format(date);


12/10/2011 02:28:28
12/10/2011 13:28:28

I would also suggest you start using Joda Time which is simply a much nicer date/time API...

EDIT: Note that if your system doesn't know about the Australia/Sydney time zone, it would show UTC. For example, if I change the code about to use TimeZone.getTimeZone("blah/blah") it will show the UTC value twice. I suggest you print TimeZone.getTimeZone("Australia/Sydney").getDisplayName() and see what it says... and check your code for typos too :)

How to minify php page html output?

Turn on gzip if you want to do it properly. You can also just do something like this:

$this->output = preg_replace(
        '/ {2,}/',
        '/<!--.*?-->|\t|(?:\r?\n[ \t]*)+/s'
        ' ',

This removes about 30% of the page size by turning your html into one line, no tabs, no new lines, no comments. Mileage may vary

'ls' is not recognized as an internal or external command, operable program or batch file

If you want to use Unix shell commands on Windows, you can use Windows Powershell, which includes both Windows and Unix commands as aliases. You can find more info on it in the documentation.

PowerShell supports aliases to refer to commands by alternate names. Aliasing allows users with experience in other shells to use common command names that they already know for similar operations in PowerShell.

The PowerShell equivalents may not produce identical results. However, the results are close enough that users can do work without knowing the PowerShell command name.

SQL Query for Student mark functionality

 select max(m.mark)  as maxMarkObtained,su.Subname from Student s 
  inner join Marks m on s.Stid=m.Stid inner join [Subject] su on
  su.Subid=m.Subid group by su.Subname

I have execute it , this should work.

Fastest way to get the first n elements of a List into an Array

Option 1 Faster Than Option 2

Because Option 2 creates a new List reference, and then creates an n element array from the List (option 1 perfectly sizes the output array). However, first you need to fix the off by one bug. Use < (not <=). Like,

String[] out = new String[n];
for(int i = 0; i < n; i++) {
    out[i] = in.get(i);

How do I get the logfile from an Android device?

Two steps:

  • Generate the log
  • Load Gmail to send the log


  1. Generate the log

    File generateLog() {
        File logFolder = new File(Environment.getExternalStorageDirectory(), "MyFolder");
        if (!logFolder.exists()) {
        String filename = "myapp_log_" + new Date().getTime() + ".log";
        File logFile = new File(logFolder, filename);
        try {
            String[] cmd = new String[] { "logcat", "-f", logFile.getAbsolutePath(), "-v", "time", "ActivityManager:W", "myapp:D" };
            Toaster.shortDebug("Log generated to: " + filename);
            return logFile;
        catch (IOException ioEx) {
        return null;
  2. Load Gmail to send the log

    File logFile = generateLog();
    Intent intent = new Intent(Intent.ACTION_SEND);
    intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(logFile));

References for #1


For #2 - there are many different answers out there for how to load the log file to view and send. Finally, the solution here actually worked to both:

  • load Gmail as an option
  • attaches the file successfully

Big thanks to for the correctly working answer

What is a 'NoneType' object?

In the error message, instead of telling you that you can't concatenate two objects by showing their values (a string and None in this example), the Python interpreter tells you this by showing the types of the objects that you tried to concatenate. The type of every string is str while the type of the single None instance is called NoneType.

You normally do not need to concern yourself with NoneType, but in this example it is necessary to know that type(None) == NoneType.

Sort collection by multiple fields in Kotlin

sortedWith + compareBy (taking a vararg of lambdas) do the trick:

val sortedList = list.sortedWith(compareBy({ it.age }, { }))

You can also use the somewhat more succinct callable reference syntax:

val sortedList = list.sortedWith(compareBy(Person::age, Person::name))

How to check if C string is empty

The shortest way to do that would be:

do {
    // Something
} while (*url);

Basically, *url will return the char at the first position in the array; since C strings are null-terminated, if the string is empty, its first position will be the character '\0', whose ASCII value is 0; since C logical statements treat every zero value as false, this loop will keep going while the first position of the string is non-null, that is, while the string is not empty.

Recommended readings if you want to understand this better:

Transferring files over SSH

You need to specify both source and destination, and if you want to copy directories you should look at the -r option.

So to recursively copy /home/user/whatever from remote server to your current directory:

scp -pr user@remoteserver:whatever .

BackgroundWorker vs background Thread

From my understanding of your question, you are using a BackgroundWorker as a standard Thread.

The reason why BackgroundWorker is recommended for things that you don't want to tie up the UI thread is because it exposes some nice events when doing Win Forms development.

Events like RunWorkerCompleted to signal when the thread has completed what it needed to do, and the ProgressChanged event to update the GUI on the threads progress.

So if you aren't making use of these, I don't see any harm in using a standard Thread for what you need to do.

Adding local .aar files to Gradle build using "flatDirs" is not working

This solution is working with Android Studio 4.0.1.

Apart from creating a new module as suggested in above solution, you can try this solution.

If you have multiple modules in your application and want to add aar to just one of the module then this solution come handy.

In your root project build.gradle


repositories {
flatDir {
    dirs 'libs'

Then in the module where you want to add the .aar file locally. simply add below lines of code.

dependencies {
api fileTree(include: ['*.aar'], dir: 'libs')
implementation files('libs/<yourAarName>.aar')


Happy Coding :)

How to redirect output of an entire shell script within the script itself?

For saving the original stdout and stderr you can use:

exec [fd number]<&1 
exec [fd number]<&2

For example, the following code will print "walla1" and "walla2" to the log file (a.txt), "walla3" to stdout, "walla4" to stderr.


exec 5<&1
exec 6<&2

exec 1> ~/a.txt 2>&1

echo "walla1"
echo "walla2" >&2
echo "walla3" >&5
echo "walla4" >&6

what is the difference between json and xml

The difference between XML and JSON is that XML is a meta-language/markup language and JSON is a lightweight data-interchange. That is, XML syntax is designed specifically to have no inherent semantics. Particular element names don't mean anything until a particular processing application processes them in a particular way. By contrast, JSON syntax has specific semantics built in stuff between {} is an object, stuff between [] is an array, etc.

A JSON parser, therefore, knows exactly what every JSON document means. An XML parser only knows how to separate markup from data. To deal with the meaning of an XML document, you have to write additional code.

To illustrate the point, let me borrow Guffa's example:

{   "persons": [
    "name": "Ford Prefect",
    "gender": "male"
   "name": "Arthur Dent",
   "gender": "male"
    "name": "Tricia McMillan",
    "gender": "female"
  }   ] }

The XML equivalent he gives is not really the same thing since while the JSON example is semantically complete, the XML would require to be interpreted in a particular way to have the same effect. In effect, the JSON is an example uses an established markup language of which the semantics are already known, whereas the XML example creates a brand new markup language without any predefined semantics.

A better XML equivalent would be to define a (fictitious) XJSON language with the same semantics as JSON, but using XML syntax. It might look something like this:

            <value>Ford Prefect</value>
            <value>Arthur Dent</value>
            <value>Tricia McMillan</value>

Once you wrote an XJSON processor, it could do exactly what JSON processor does, for all the types of data that JSON can represent, and you could translate data losslessly between JSON and XJSON.

So, to complain that XML does not have the same semantics as JSON is to miss the point. XML syntax is semantics-free by design. The point is to provide an underlying syntax that can be used to create markup languages with any semantics you want. This makes XML great for making up ad-hoc data and document formats, because you don't have to build parsers for them, you just have to write a processor for them.

But the downside of XML is that the syntax is verbose. For any given markup language you want to create, you can come up with a much more succinct syntax that expresses the particular semantics of your particular language. Thus JSON syntax is much more compact than my hypothetical XJSON above.

If follows that for really widely used data formats, the extra time required to create a unique syntax and write a parser for that syntax is offset by the greater succinctness and more intuitive syntax of the custom markup language. It also follows that it often makes more sense to use JSON, with its established semantics, than to make up lots of XML markup languages for which you then need to implement semantics.

It also follows that it makes sense to prototype certain types of languages and protocols in XML, but, once the language or protocol comes into common use, to think about creating a more compact and expressive custom syntax.

It is interesting, as a side note, that SGML recognized this and provided a mechanism for specifying reduced markup for an SGML document. Thus you could actually write an SGML DTD for JSON syntax that would allow a JSON document to be read by an SGML parser. XML removed this capability, which means that, today, if you want a more compact syntax for a specific markup language, you have to leave XML behind, as JSON does.

nvarchar(max) vs NText

nvarchar(max) is what you want to be using. The biggest advantage is that you can use all the T-SQL string functions on this data type. This is not possible with ntext. I'm not aware of any real disadvantages.

position fixed is not working

My issue was that a parent element had transform: scale(1); this apparently makes it impossible for any element to be fixed inside it. By removing that everything works normally...

It seems to be like this in all browsers I tested (Chrome, Safari) so don't know if it comes from some strange web standard.

(It's a popup that goes from scale(0) to scale(1))

Switch statement for greater-than/less-than

In my case (color-coding a percentage, nothing performance-critical), I quickly wrote this:

function findColor(progress) {
    const thresholds = [30, 60];
    const colors = ["#90B451", "#F9A92F", "#90B451"];

    return colors.find((col, index) => {
        return index >= thresholds.length || progress < thresholds[index];

How to call window.alert("message"); from C#?

Do you mean, a message box?

MessageBox.Show("Error Message", "Error Title", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);

More information here:

How can I disable the UITableView selection?

You can also disable selection of row from interface builder itself by choosing NoSelection from the selection option(of UITableView Properties) in inspector pane as shown in the below image

UITableView Inspector

How do we check if a pointer is NULL pointer?

Well, this question was asked and answered way back in 2011, but there is nullptrin C++11. That's all I'm using currently.

You can read more from Stack Overflow and also from this article.

Python check if list items are integers?

Fast, simple, but maybe not always right:

>>> [x for x in mylist if x.isdigit()]
['1', '2', '3', '4']

More traditional if you need to get numbers:

new_list = []
for value in mylist:
    except ValueError:

Note: The result has integers. Convert them back to strings if needed, replacing the lines above with:


Java - Reading XML file

Reading xml the easy way:

package com.mkyong.core;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

public class Customer {

    String name;
    int age;
    int id;

    public String getName() {
        return name;

    public void setName(String name) { = name;

    public int getAge() {
        return age;

    public void setAge(int age) {
        this.age = age;

    public int getId() {
        return id;

    public void setId(int id) { = id;



package com.mkyong.core;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBExample {
    public static void main(String[] args) {

      Customer customer = new Customer();

      try {

        File file = new File("C:\\file.xml");
        JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

        // output pretty printed
        jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        jaxbMarshaller.marshal(customer, file);
        jaxbMarshaller.marshal(customer, System.out);

          } catch (JAXBException e) {


Parse XML document in C#

Try this:

XmlDocument doc = new XmlDocument();

Or alternatively if you have the XML in a string use the LoadXml method.

Once you have it loaded, you can use SelectNodes and SelectSingleNode to query specific values, for example:

XmlNode node = doc.SelectSingleNode("//Company/Email/text()");
// node.Value contains "[email protected]"

Finally, note that your XML is invalid as it doesn't contain a single root node. It must be something like this:

        <Email>[email protected]</Email>

Custom thread pool in Java 8 parallel stream

I tried the custom ForkJoinPool as follows to adjust the pool size:

private static Set<String> ThreadNameSet = new HashSet<>();
private static Callable<Long> getSum() {
    List<Long> aList = LongStream.rangeClosed(0, 10_000_000).boxed().collect(Collectors.toList());
    return () -> aList.parallelStream()
            .peek((i) -> {
                String threadName = Thread.currentThread().getName();
            .reduce(0L, Long::sum);

private static void testForkJoinPool() {
    final int parallelism = 10;

    ForkJoinPool forkJoinPool = null;
    Long result = 0L;
    try {
        forkJoinPool = new ForkJoinPool(parallelism);
        result = forkJoinPool.submit(getSum()).get(); //this makes it an overall blocking call

    } catch (InterruptedException | ExecutionException e) {
    } finally {
        if (forkJoinPool != null) {
            forkJoinPool.shutdown(); //always remember to shutdown the pool

Here is the output saying the pool is using more threads than the default 4.

[ForkJoinPool-1-worker-8, ForkJoinPool-1-worker-9, ForkJoinPool-1-worker-6, ForkJoinPool-1-worker-11, ForkJoinPool-1-worker-10, ForkJoinPool-1-worker-1, ForkJoinPool-1-worker-15, ForkJoinPool-1-worker-13, ForkJoinPool-1-worker-4, ForkJoinPool-1-worker-2]

But actually there is a weirdo, when I tried to achieve the same result using ThreadPoolExecutor as follows:

BlockingDeque blockingDeque = new LinkedBlockingDeque(1000);
ThreadPoolExecutor fixedSizePool = new ThreadPoolExecutor(10, 20, 60, TimeUnit.SECONDS, blockingDeque, new MyThreadFactory("my-thread"));

but I failed.

It will only start the parallelStream in a new thread and then everything else is just the same, which again proves that the parallelStream will use the ForkJoinPool to start its child threads.

How do I convert an array object to a string in PowerShell?

I found that piping the array to the Out-String cmdlet works well too.

For example:

PS C:\> $a  | out-string


It depends on your end goal as to which method is the best to use.

How to make Java honor the DNS Caching Timeout?

To expand on Byron's answer, I believe you need to edit the file in the %JRE_HOME%\lib\security directory to effect this change.

Here is the relevant section:

# The Java-level namelookup cache policy for successful lookups:
# any negative value: caching forever
# any positive value: the number of seconds to cache an address for
# zero: do not cache
# default value is forever (FOREVER). For security reasons, this
# caching is made forever when a security manager is set. When a security
# manager is not set, the default behavior is to cache for 30 seconds.
# NOTE: setting this to anything other than the default value can have
#       serious security implications. Do not set it unless 
#       you are sure you are not exposed to DNS spoofing attack.

Documentation on the file here.

change html text from link with jquery

$('#a_tbnotesverbergen').text('My New Link Text');


$('#a_tbnotesverbergen').html('My New Link Text or HTML');

Merge Two Lists in R

merged = map(names(first), ~c(first[[.x]], second[[.x]])
merged = set_names(merged, names(first))

Using purrr. Also solves the problem of your lists not being in order.

String comparison technique used by Python

Strings are compared lexicographically using the numeric equivalents (the result of the built-in function ord()) of their characters. Unicode and 8-bit strings are fully interoperable in this behavior.

Sorting string array in C#

This code snippet is working properly enter image description here

Jupyter Notebook not saving: '_xsrf' argument missing from post

The easiest way I found is this:

Just open another (non-running, existing) notebook on the same kernel, and the issue is magically gone; you can again save the notebooks that were previously showing the _xsrf error.

If you have already closed the Jupyter home page, you can find a link to it on the terminal from which Jupyter was started.

Changing the current working directory in Java?

You can change the process's actual working directory using JNI or JNA.

With JNI, you can use native functions to set the directory. The POSIX method is chdir(). On Windows, you can use SetCurrentDirectory().

With JNA, you can wrap the native functions in Java binders.

For Windows:

private static interface MyKernel32 extends Library {
    public MyKernel32 INSTANCE = (MyKernel32) Native.loadLibrary("Kernel32", MyKernel32.class);

    /** BOOL SetCurrentDirectory( LPCTSTR lpPathName ); */
    int SetCurrentDirectoryW(char[] pathName);

For POSIX systems:

private interface MyCLibrary extends Library {
    MyCLibrary INSTANCE = (MyCLibrary) Native.loadLibrary("c", MyCLibrary.class);

    /** int chdir(const char *path); */
    int chdir( String path );

How to append in a json file in Python?

json_obj=json.dumps(a_dict, ensure_ascii=False)

What is the SQL command to return the field names of a table?

MySQL 3 and 4 (and 5):

desc tablename

which is an alias for

show fields from tablename

SQL Server (from 2000) and MySQL 5:

where TABLE_NAME = 'tablename'

Completing the answer: like people below have said, in SQL Server you can also use the stored procedure sp_help

exec sp_help 'tablename'

There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key country

try this

@Html.DropDownList("ddlcountry",(List<SelectListItem>)ViewBag.countrydrop,"Select country")

In Controller

ViewBag.countrydrop = ds.getcountry().Select(x => new SelectListItem { Text =, Value = x.countryid.ToString() }).ToList();

Get last record of a table in Postgres

If you accept a tip, create an id in this table like serial. The default of this field will be:


So, you use a query to call the last register. Using your example:

pg_query($connection, "SELECT currval('table_name_field_seq') AS id;

I hope this tip helps you.

Set form backcolor to custom color

With Winforms you can use Form.BackColor to do this.
From within the Form's code:

BackColor = Color.LightPink;

If you mean a WPF Window you can use the Background property.
From within the Window's code:

Background = Brushes.LightPink;

Python re.sub(): how to substitute all 'u' or 'U's with 'you'

Another possible solution I came up with was:

re.sub(r'([uU]+(.)?\s)',' you ', text)

How to select multiple rows filled with constants?

In Oracle

    WHEN level = 1
    THEN 'HI'
    WHEN level = 2
    THEN 'BYE'
FROM dual
  CONNECT BY level <= 2;

Cursor adapter and sqlite example

In Android, How to use a Cursor with a raw query in sqlite:

Cursor c = sampleDB.rawQuery("SELECT FirstName, Age FROM mytable " +
           "where Age > 10 LIMIT 5", null);

if (c != null ) {
    if  (c.moveToFirst()) {
        do {
            String firstName = c.getString(c.getColumnIndex("FirstName"));
            int age = c.getInt(c.getColumnIndex("Age"));
            results.add("" + firstName + ",Age: " + age);
        }while (c.moveToNext());

Best font for coding

I like Consolas a lot. This top-10 list is a good resource for others. It includes examples and descriptions.

Remove specific commit

So it sounds like the bad commit was incorporated in a merge commit at some point. Has your merge commit been pulled yet? If yes, then you'll want to use git revert; you'll have to grit your teeth and work through the conflicts. If no, then you could conceivably either rebase or revert, but you can do so before the merge commit, then redo the merge.

There's not much help we can give you for the first case, really. After trying the revert, and finding that the automatic one failed, you have to examine the conflicts and fix them appropriately. This is exactly the same process as fixing merge conflicts; you can use git status to see where the conflicts are, edit the unmerged files, find the conflicted hunks, figure out how to resolve them, add the conflicted files, and finally commit. If you use git commit by itself (no -m <message>), the message that pops up in your editor should be the template message created by git revert; you can add a note about how you fixed the conflicts, then save and quit to commit.

For the second case, fixing the problem before your merge, there are two subcases, depending on whether you've done more work since the merge. If you haven't, you can simply git reset --hard HEAD^ to knock off the merge, do the revert, then redo the merge. But I'm guessing you have. So, you'll end up doing something like this:

  • create a temporary branch just before the merge, and check it out
  • do the revert (or use git rebase -i <something before the bad commit> <temporary branch> to remove the bad commit)
  • redo the merge
  • rebase your subsequent work back on: git rebase --onto <temporary branch> <old merge commit> <real branch>
  • remove the temporary branch

How can I use Guzzle to send a POST request in JSON?

For Guzzle 5, 6 and 7 you do it like this:

use GuzzleHttp\Client;

$client = new Client();

$response = $client->post('url', [
    GuzzleHttp\RequestOptions::JSON => ['foo' => 'bar'] // or 'json' => [...]


Swapping pointers in C (char, int)

If you have the luxury of working in C++, use this:

template<typename T>
void swapPrimitives(T& a, T& b)
    T c = a;
    a = b;
    b = c;

Granted, in the case of char*, it would only swap the pointers themselves, not the data they point to, but in most cases, that is OK, right?

Should I use PATCH or PUT in my REST API?

The PATCH method is the correct choice here as you're updating an existing resource - the group ID. PUT should only be used if you're replacing a resource in its entirety.

Further information on partial resource modification is available in RFC 5789. Specifically, the PUT method is described as follows:

Several applications extending the Hypertext Transfer Protocol (HTTP) require a feature to do partial resource modification. The existing HTTP PUT method only allows a complete replacement of a document. This proposal adds a new HTTP method, PATCH, to modify an existing HTTP resource.

WordPress is giving me 404 page not found for all pages except the homepage

.htaccess is a hidden file, so you must set all files as visible in your ftp.

I suggest you return your permalink structure to default ( ?p=ID ) so you ensure that .htaccess is the problem.

After that, you could simply set "month and name" structure again, and see if it works.

PS: Have you upgraded to 3.1? I've seen some people with plugin issues in this case.

Replace string within file contents


with open(FileName) as f:'A', 'Orange')

with open(FileName, "w") as f:

how to remove css property using javascript?

To change all classes for an element:

document.getElementById("ElementID").className = "CssClass";

To add an additional class to an element:

document.getElementById("ElementID").className += " CssClass";

To check if a class is already applied to an element:

if ( document.getElementById("ElementID").className.match(/(?:^|\s)CssClass(?!\S)/) )

Capitalize only first character of string and leave others alone? (Rails)

Rails starting from version 5.2.3 has upcase_first method.

For example, "my Test string".upcase_first will return My Test string.

In Linux, how to tell how much memory processes are using?

You can use pmap + awk.

Most likely, we're interested in the RSS memory which is the 3rd column in the last line of the example pmap output below (82564).

$ pmap -x <pid>

Address           Kbytes     RSS   Dirty Mode   Mapping


00007f9caf3e7000       4       4       4 r----
00007f9caf3e8000       8       8       8 rw---
00007fffe8931000     132      12      12 rw---    [ stack ]
00007fffe89fe000       8       8       0 r-x--    [ anon ]
ffffffffff600000       4       0       0 r-x--    [ anon ]
----------------  ------  ------  ------
total kB          688584   82564    9592

Awk is then used to extract that value.

$ pmap -x <pid> | awk '/total/ { print $4 "K" }'

The pmap values are in kilobytes. If we wanted it in megabytes, we could do something like this.

$ pmap -x <pid> | awk '/total/ { print $4 / 1024 "M" }'

Multiple file upload in php

Multiple files can be selected and then uploaded using the
<input type='file' name='file[]' multiple>
The sample php script that does the uploading:

            foreach ($_FILES['file']['name'] as $filename) 
                $count=$count + 1;

The selected files are received as an array with

$_FILES['file']['name'][0] storing the name of first file.
$_FILES['file']['name'][1] storing the name of second file.
and so on.

Save image from url with curl PHP

Improved version of Komang answer (add referer and user agent, check if you can write the file), return true if it's ok, false if there is an error :

public function downloadImage($url,$filename){
    $fp = fopen($filename,'w');
        $ch = curl_init ($url);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
        $result = parse_url($url);
        curl_setopt($ch, CURLOPT_REFERER, $result['scheme'].'://'.$result['host']);
        curl_setopt($ch, CURLOPT_USERAGENT,'Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0');
        curl_close ($ch);
            fwrite($fp, $raw);
            return false;
        return true;
    return false;

Neither BindingResult nor plain target object for bean name available as request attr

Try adding a BindingResult parameter to methods annotated with @RequestMapping which have a @ModelAttribute annotated parameters. After each @ModelAttribute parameter, Spring looks for a BindingResult in the next parameter position (order is important).

So try changing:

@RequestMapping(method = RequestMethod.POST)
public String loadCharts(HttpServletRequest request, ModelMap model, @ModelAttribute("sideForm") Chart chart) 


@RequestMapping(method = RequestMethod.POST)
public String loadCharts(@ModelAttribute("sideForm") Chart chart, BindingResult bindingResult, HttpServletRequest request, ModelMap model) 

Convert NVARCHAR to DATETIME in SQL Server 2008

DECLARE @chr nvarchar(50) = (SELECT CONVERT(nvarchar(50), GETDATE(), 103))

SELECT @chr chars, CONVERT(date, @chr, 103) date_again

Why does the program give "illegal start of type" error?

You have an extra '{' before return type. You may also want to put '==' instead of '=' in if and else condition.

How do you scroll up/down on the console of a Linux VM


Ctrl + Shift + Up Arrow or Down Arrow

Unlike Shift + Page Up or Page Down, which scrolls the entire page, this will help with a smoother line-by-line scrolling, which is exactly what I was looking for.

Windows XP or later Windows: How can I run a batch file in the background with no window displayed?

In the other question I suggested autoexnt. That is also possible in this situation. Just set the service to run manually (ie not automatic at startup). When you want to run your batch, modify the autoexnt.bat file to call the batch file you want, and start the autoexnt service.

The batchfile to start this, can look like this (untested):

echo call c:\path\to\batch.cmd %* > c:\windows\system32\autoexnt.bat
net start autoexnt

Note that batch files started this way run as the system user, which means you do not have access to network shares automatically. But you can use net use to connect to a remote server.

You have to download the Windows 2003 Resource Kit to get it. The Resource Kit can also be installed on other versions of windows, like Windows XP.

How to format a duration in java? (e.g format H:MM:SS)

in scala, no library needed:

def prettyDuration(str:List[String],seconds:Long):List[String]={
  seconds match {
    case t if t < 60 => str:::List(s"${t} seconds")
    case t if (t >= 60 && t< 3600 ) => List(s"${t / 60} minutes"):::prettyDuration(str, t%60)
    case t if (t >= 3600 && t< 3600*24 ) => List(s"${t / 3600} hours"):::prettyDuration(str, t%3600)
    case t if (t>= 3600*24 ) => List(s"${t / (3600*24)} days"):::prettyDuration(str, t%(3600*24))
val dur = prettyDuration(List.empty[String], 12345).mkString("")

lambda expression join multiple tables with select and where clause

I was looking for something and I found this post. I post this code that managed many-to-many relationships in case someone needs it.

    var UserInRole = db.UsersInRoles.Include(u => u.UserProfile).Include(u => u.Roles)
    .Select (m => new 
        UserName = u.UserProfile.UserName,
        RoleName = u.Roles.RoleName

View/edit ID3 data for MP3 files

Thirding TagLib Sharp.

TagLib.File f = TagLib.File.Create(path);
f.Tag.Album = "New Album Title";

Can't open file 'svn/repo/db/txn-current-lock': Permission denied

I also had this problem recently, and it was the SELinux which caused it. I was trying to have the post-commit of subversion to notify Jenkins that the code has change so Jenkins would do a build and deploy to Nexus.

I had to do the following to get it to work.

1) First I checked if SELinux is enabled:

    less /selinux/enforce

This will output 1 (for on) or 0 (for off)

2) Temporary disable SELinux:

    echo 0 > /selinux/enforce

Now test see if it works now.

3) Enable SELinux:

    echo 1 > /selinux/enforce

Change the policy for SELinux.

4) First view the current configuration:

    /usr/sbin/getsebool -a | grep httpd

This will give you: httpd_can_network_connect --> off

5) Set this to on and your post-commit will work with SELinux:

    /usr/sbin/setsebool -P httpd_can_network_connect on

Now it should be working again.

Operand type clash: uniqueidentifier is incompatible with int

If you're accessing this via a View then try sp_recompile or refreshing views.


Causes stored procedures, triggers, and user-defined functions to be recompiled the next time that they are run. It does this by dropping the existing plan from the procedure cache forcing a new plan to be created the next time that the procedure or trigger is run. In a SQL Server Profiler collection, the event SP:CacheInsert is logged instead of the event SP:Recompile.


[ @objname= ] 'object'

The qualified or unqualified name of a stored procedure, trigger, table, view, or user-defined function in the current database. object is nvarchar(776), with no default. If object is the name of a stored procedure, trigger, or user-defined function, the stored procedure, trigger, or function will be recompiled the next time that it is run. If object is the name of a table or view, all the stored procedures, triggers, or user-defined functions that reference the table or view will be recompiled the next time that they are run.

Return Code Values

0 (success) or a nonzero number (failure)


sp_recompile looks for an object in the current database only.

The queries used by stored procedures, or triggers, and user-defined functions are optimized only when they are compiled. As indexes or other changes that affect statistics are made to the database, compiled stored procedures, triggers, and user-defined functions may lose efficiency. By recompiling stored procedures and triggers that act on a table, you can reoptimize the queries.

nullable object must have a value

I got this message when trying to access values of a null valued object.

sName = myObj.Name;

this will produce error. First you should check if object not null

if(myObj != null)
  sName = myObj.Name;

This works.

Disable sorting on last column when using jQuery DataTables

Its work for me - you can try this

    "paging":   true,
    "ordering": false,
    "info":     true,

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

Use ng-click in place of onclick. and its as simple as that:

<a href="" ng-click="return theFunction();">Item</a>

<script type="text/javascript">
function theFunction () {
    // return true or false, depending on whether you want to allow 
    // the`href` property to follow through or not

Jquery button click() function is not working

After making the id unique across the document ,You have to use event delegation

$("#container").on("click", "buttonid", function () {

Execute the setInterval function without delay the first time

To solve this problem , I run the function a first time after the page has loaded.

function foo(){ ... }

window.onload = function() {

}, 5000);

Removing empty lines in Notepad++

In notepad++ press CTRL+H , in search mode click on the "Extended (\n, \r, \t ...)" radio button then type in the "Find what" box: \r\n (short for CR LF) and leave the "Replace with" box empty..

Finally hit replace all

How can I completely remove TFS Bindings

Sometime, the binding info is cached

To clear Team Explorer's cache:

Go to C:\Users\<user>\AppData\Local\Microsoft\Team Foundation\2.0
Delete or rename the Cache folder.

This come from a website I could not find now. Thanks for that guy for the tip.

Validate Dynamically Added Input fields

$('#form-btn').click(function () {
//set global rules & messages array to use in validator
   var rules = {};
   var messages = {};
//get input, select, textarea of form
   $('#formId').find('input, select, textarea').each(function () {
      var name = $(this).attr('name');
      rules[name] = {};
      messages[name] = {};

      rules[name] = {required: true}; // set required true against every name
//apply more rules, you can also apply custom rules & messages
      if (name === "email") {
         rules[name].email = true;
         //messages[name].email = "Please provide valid email";
      else if(name==='url'){
        rules[name].required = false; // url filed is not required
//add other rules & messages
//submit form and use above created global rules & messages array
   $('#formId').submit(function (e) {
            rules: rules,
            messages: messages,
            submitHandler: function (form) {
            console.log("validation success");

count (non-blank) lines-of-code in bash

'wc' counts lines, words, chars, so to count all lines (including blank ones) use:

wc *.py

To filter out the blank lines, you can use grep:

grep -v '^\s*$' *.py | wc

'-v' tells grep to output all lines except those that match '^' is the start of a line '\s*' is zero or more whitespace characters '$' is the end of a line *.py is my example for all the files you wish to count (all python files in current dir) pipe output to wc. Off you go.

I'm answering my own (genuine) question. Couldn't find an stackoverflow entry that covered this.

How to crop an image using C#?

here it is working demo on github

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>

<!DOCTYPE html>
<html xmlns="">
<head runat="server">
 <link href="css/jquery.Jcrop.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src=""></script>
<script type="text/javascript" src="js/jquery.Jcrop.js"></script>
  <form id="form2" runat="server">
    <asp:Panel ID="pnlUpload" runat="server">
      <asp:FileUpload ID="Upload" runat="server" />
      <br />
      <asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" Text="Upload" />
      <asp:Label ID="lblError" runat="server" Visible="false" />
    <asp:Panel ID="pnlCrop" runat="server" Visible="false">
      <asp:Image ID="imgCrop" runat="server" />
      <br />
      <asp:HiddenField ID="X" runat="server" />
      <asp:HiddenField ID="Y" runat="server" />
      <asp:HiddenField ID="W" runat="server" />
      <asp:HiddenField ID="H" runat="server" />
      <asp:Button ID="btnCrop" runat="server" Text="Crop" OnClick="btnCrop_Click" />
    <asp:Panel ID="pnlCropped" runat="server" Visible="false">
      <asp:Image ID="imgCropped" runat="server" />
    <script type="text/javascript">
  jQuery(document).ready(function() {
      onSelect: storeCoords

  function storeCoords(c) {


C# code logic for upload and crop.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using SD = System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace WebApplication1
    public partial class WebForm1 : System.Web.UI.Page
        String path = HttpContext.Current.Request.PhysicalApplicationPath + "images\\";
        protected void Page_Load(object sender, EventArgs e)

        protected void btnUpload_Click(object sender, EventArgs e)
            Boolean FileOK = false;
            Boolean FileSaved = false;

            if (Upload.HasFile)
                Session["WorkingImage"] = Upload.FileName;
                String FileExtension = Path.GetExtension(Session["WorkingImage"].ToString()).ToLower();
                String[] allowedExtensions = { ".png", ".jpeg", ".jpg", ".gif" };
                for (int i = 0; i < allowedExtensions.Length; i++)
                    if (FileExtension == allowedExtensions[i])
                        FileOK = true;

            if (FileOK)
                    Upload.PostedFile.SaveAs(path + Session["WorkingImage"]);
                    FileSaved = true;
                catch (Exception ex)
                    lblError.Text = "File could not be uploaded." + ex.Message.ToString();
                    lblError.Visible = true;
                    FileSaved = false;
                lblError.Text = "Cannot accept files of this type.";
                lblError.Visible = true;

            if (FileSaved)
                pnlUpload.Visible = false;
                pnlCrop.Visible = true;
                imgCrop.ImageUrl = "images/" + Session["WorkingImage"].ToString();

        protected void btnCrop_Click(object sender, EventArgs e)
            string ImageName = Session["WorkingImage"].ToString();
            int w = Convert.ToInt32(W.Value);
            int h = Convert.ToInt32(H.Value);
            int x = Convert.ToInt32(X.Value);
            int y = Convert.ToInt32(Y.Value);

            byte[] CropImage = Crop(path + ImageName, w, h, x, y);
            using (MemoryStream ms = new MemoryStream(CropImage, 0, CropImage.Length))
                ms.Write(CropImage, 0, CropImage.Length);
                using (SD.Image CroppedImage = SD.Image.FromStream(ms, true))
                    string SaveTo = path + "crop" + ImageName;
                    CroppedImage.Save(SaveTo, CroppedImage.RawFormat);
                    pnlCrop.Visible = false;
                    pnlCropped.Visible = true;
                    imgCropped.ImageUrl = "images/crop" + ImageName;

        static byte[] Crop(string Img, int Width, int Height, int X, int Y)
                using (SD.Image OriginalImage = SD.Image.FromFile(Img))
                    using (SD.Bitmap bmp = new SD.Bitmap(Width, Height))
                        bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);
                        using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
                            Graphic.SmoothingMode = SmoothingMode.AntiAlias;
                            Graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
                            Graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
                            Graphic.DrawImage(OriginalImage, new SD.Rectangle(0, 0, Width, Height), X, Y, Width, Height, SD.GraphicsUnit.Pixel);
                            MemoryStream ms = new MemoryStream();
                            bmp.Save(ms, OriginalImage.RawFormat);
                            return ms.GetBuffer();
            catch (Exception Ex)
                throw (Ex);

What is the easiest way to remove all packages installed by pip?

Method 1 (with pip freeze)

pip freeze | xargs pip uninstall -y

Method 2 (with pip list)

pip list | awk '{print $1}' | xargs pip uninstall -y

Method 3 (with virtualenv)

virtualenv --clear MYENV

Python: Converting from ISO-8859-1/latin1 to UTF-8

Try decoding it first, then encoding:


How to add a where clause in a MySQL Insert statement?

INSERT INTO users (id,username, password) 
VALUES ('1','Jack','123')
ON DUPLICATE KEY UPDATE username='Jack',password='123'

This will work only if the id field is unique/pk (not composite PK though) Also, this will insert if no id of value 1 is found and update otherwise the record with id 1 if it does exists.

How do I invoke a Java method when given the method name as a string?

For those who want a straight-forward code example in Java 7:

Dog class:

package com.mypackage.bean;

public class Dog {
    private String name;
    private int age;

    public Dog() {
        // empty constructor

    public Dog(String name, int age) { = name;
        this.age = age;

    public String getName() {
        return name;

    public void setName(String name) { = name;

    public int getAge() {
        return age;

    public void setAge(int age) {
        this.age = age;

    public void printDog(String name, int age) {
        System.out.println(name + " is " + age + " year(s) old.");

ReflectionDemo class:

package com.mypackage.demo;

import java.lang.reflect.*;

public class ReflectionDemo {

    public static void main(String[] args) throws Exception {
        String dogClassName = "com.mypackage.bean.Dog";
        Class<?> dogClass = Class.forName(dogClassName); // convert string classname to class
        Object dog = dogClass.newInstance(); // invoke empty constructor

        String methodName = "";

        // with single parameter, return void
        methodName = "setName";
        Method setNameMethod = dog.getClass().getMethod(methodName, String.class);
        setNameMethod.invoke(dog, "Mishka"); // pass arg

        // without parameters, return string
        methodName = "getName";
        Method getNameMethod = dog.getClass().getMethod(methodName);
        String name = (String) getNameMethod.invoke(dog); // explicit cast

        // with multiple parameters
        methodName = "printDog";
        Class<?>[] paramTypes = {String.class, int.class};
        Method printDogMethod = dog.getClass().getMethod(methodName, paramTypes);
        printDogMethod.invoke(dog, name, 3); // pass args

Output: Mishka is 3 year(s) old.

You can invoke the constructor with parameters this way:

Constructor<?> dogConstructor = dogClass.getConstructor(String.class, int.class);
Object dog = dogConstructor.newInstance("Hachiko", 10);

Alternatively, you can remove

String dogClassName = "com.mypackage.bean.Dog";
Class<?> dogClass = Class.forName(dogClassName);
Object dog = dogClass.newInstance();

and do

Dog dog = new Dog();

Method method = Dog.class.getMethod(methodName, ...);
method.invoke(dog, ...);

Suggested reading: Creating New Class Instances

@synthesize vs @dynamic, what are the differences?

As per the Apple documentation.

You use the @synthesize statement in a class’s implementation block to tell the compiler to create implementations that match the specification you gave in the @property declaration.

You use the @dynamic statement to tell the compiler to suppress a warning if it can’t find an implementation of accessor methods specified by an @property declaration.

More info:-

ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

from here ORA-00054: resource busy and acquire with NOWAIT specified

You can also look up the sql,username,machine,port information and get to the actual process which holds the connection


What .NET collection provides the fastest search

You should read this blog that speed tested several different types of collections and methods for each using both single and multi-threaded techniques.

According to the results, a BinarySearch on a List and SortedList were the top performers constantly running neck-in-neck when looking up something as a "value".

When using a collection that allows for "keys", the Dictionary, ConcurrentDictionary, Hashset, and HashTables performed the best overall.

How to install MySQLdb package? (ImportError: No module named setuptools)

If MySQLdb's now distributed in a way that requires setuptools, your choices are either to download the latter (e.g. from here) or refactor MySQLdb's to bypass setuptools (maybe just importing setup and Extension from plain distutils instead might work, but you may also need to edit some of the setup_*.py files in the same directory).

Depending on how your site's Python installation is configured, installing extensions for your own individual use without requiring sysadm rights may be hard, but it's never truly impossible if you have shell access. You'll need to tweak your Python's sys.path to start with a directory of your own that's your personal equivalent of the system-wide site pacages directory, e.g. by setting PYTHONPATH persistently in your own environment, and then manually place in said personal directory what normal installs would normally place in site-packages (and/or subdirectories thereof).

Where IN clause in LINQ

This little bit different idea. But it will useful to you. I have used sub query to inside the linq main query.


Let say we have document table. Schema as follows schema : document(name,version,auther,modifieddate) composite Keys : name,version

So we need to get latest versions of all documents.


 var result = (from t in Context.document
                          where ((from tt in Context.document where t.Name == tt.Name
                                orderby tt.Version descending select new {Vesion=tt.Version}).FirstOrDefault()).Vesion.Contains(t.Version)
                          select t).ToList();

Viewing unpushed Git commits

You can do this with git log:

git log origin..

Assuming that origin is the name of your upstream, leaving off any revision name after .. implies HEAD, which lists the new commits that haven't been pushed.

ASP.NET MVC: What is the correct way to redirect to pages/actions in MVC?

RedirectToAction("actionName", "controllerName");

It has other overloads as well, please check up!

Also, If you are new and you are not using T4MVC, then I would recommend you to use it!

It gives you intellisence for actions,Controllers,views etc (no more magic strings)

What is the best way to use a HashMap in C++?

The standard library includes the ordered and the unordered map (std::map and std::unordered_map) containers. In an ordered map the elements are sorted by the key, insert and access is in O(log n). Usually the standard library internally uses red black trees for ordered maps. But this is just an implementation detail. In an unordered map insert and access is in O(1). It is just another name for a hashtable.

An example with (ordered) std::map:

#include <map>
#include <iostream>
#include <cassert>

int main(int argc, char **argv)
  std::map<std::string, int> m;
  m["hello"] = 23;
  // check if key is present
  if (m.find("world") != m.end())
    std::cout << "map contains key world!\n";
  // retrieve
  std::cout << m["hello"] << '\n';
  std::map<std::string, int>::iterator i = m.find("hello");
  assert(i != m.end());
  std::cout << "Key: " << i->first << " Value: " << i->second << '\n';
  return 0;


Key: hello Value: 23

If you need ordering in your container and are fine with the O(log n) runtime then just use std::map.

Otherwise, if you really need a hash-table (O(1) insert/access), check out std::unordered_map, which has a similar to std::map API (e.g. in the above example you just have to search and replace map with unordered_map).

The unordered_map container was introduced with the C++11 standard revision. Thus, depending on your compiler, you have to enable C++11 features (e.g. when using GCC 4.8 you have to add -std=c++11 to the CXXFLAGS).

Even before the C++11 release GCC supported unordered_map - in the namespace std::tr1. Thus, for old GCC compilers you can try to use it like this:

#include <tr1/unordered_map>

std::tr1::unordered_map<std::string, int> m;

It is also part of boost, i.e. you can use the corresponding boost-header for better portability.

Android textview usage as label and value

You should implement a Custom List View, such that you define a Layout once and draw it for every row in the list view.

Calculate AUC in R?

As mentioned by others, you can compute the AUC using the ROCR package. With the ROCR package you can also plot the ROC curve, lift curve and other model selection measures.

You can compute the AUC directly without using any package by using the fact that the AUC is equal to the probability that a true positive is scored greater than a true negative.

For example, if pos.scores is a vector containing a score of the positive examples, and neg.scores is a vector containing the negative examples then the AUC is approximated by:

> mean(sample(pos.scores,1000,replace=T) > sample(neg.scores,1000,replace=T))
[1] 0.7261

will give an approximation of the AUC. You can also estimate the variance of the AUC by bootstrapping:

> aucs = replicate(1000,mean(sample(pos.scores,1000,replace=T) > sample(neg.scores,1000,replace=T)))