Programs & Examples On #Identity

An inherent property of an entity that distinguishes that entity from all others. Frequently used to refer to user identity and authentication.

What is the difference between == and equals() in Java?

 String w1 ="Sarat";
 String w2 ="Sarat";
 String w3 = new String("Sarat");

 System.out.println(w1.hashCode());   //3254818
 System.out.println(w2.hashCode());   //3254818
 System.out.println(w3.hashCode());   //3254818

 System.out.println(System.identityHashCode(w1)); //prints 705927765
 System.out.println(System.identityHashCode(w2)); //prints 705927765
 System.out.println(System.identityHashCode(w3)); //prints 366712642

 if(w1==w2)   //  (705927765==705927765)
 //prints true

 if(w2==w3)   //  (705927765==366712642)
 //prints false

 if(w2.equals(w3))   //  (Content of 705927765== Content of 366712642)
 //prints true

How to get the unique ID of an object which overrides hashCode()?

I had the same issue and was not satisfied with any of the answers so far since none of them guaranteed unique IDs.

I too wanted to print object IDs for debugging purposed. I knew there must be some way to do it, because in the Eclipse debugger, it specifies unique IDs for each object.

I came up with a solution based on the fact that the "==" operator for objects only returns true if the two objects are actually the same instance.

import java.util.HashMap;
import java.util.Map;

 *  Utility for assigning a unique ID to objects and fetching objects given
 *  a specified ID
public class ObjectIDBank {

    /**Singleton instance*/
    private static ObjectIDBank instance;

    /**Counting value to ensure unique incrementing IDs*/
    private long nextId = 1;

    /** Map from ObjectEntry to the objects corresponding ID*/
    private Map<ObjectEntry, Long> ids = new HashMap<ObjectEntry, Long>();

    /** Map from assigned IDs to their corresponding objects */
    private Map<Long, Object> objects = new HashMap<Long, Object>();

    /**Private constructor to ensure it is only instantiated by the singleton pattern*/
    private ObjectIDBank(){}

    /**Fetches the singleton instance of ObjectIDBank */
    public static ObjectIDBank instance() {
        if(instance == null)
            instance = new ObjectIDBank();

        return instance;

    /** Fetches a unique ID for the specified object. If this method is called multiple
     * times with the same object, it is guaranteed to return the same value. It is also guaranteed
     * to never return the same value for different object instances (until we run out of IDs that can
     * be represented by a long of course)
     * @param obj The object instance for which we want to fetch an ID
     * @return Non zero unique ID or 0 if obj == null
    public long getId(Object obj) {

        if(obj == null)
            return 0;

        ObjectEntry objEntry = new ObjectEntry(obj);

        if(!ids.containsKey(objEntry)) {
            ids.put(objEntry, nextId);
            objects.put(nextId++, obj);

        return ids.get(objEntry);

     * Fetches the object that has been assigned the specified ID, or null if no object is
     * assigned the given id
     * @param id Id of the object
     * @return The corresponding object or null
    public Object getObject(long id) {
        return objects.get(id);

     * Wrapper around an Object used as the key for the ids map. The wrapper is needed to
     * ensure that the equals method only returns true if the two objects are the same instance
     * and to ensure that the hash code is always the same for the same instance.
    private class ObjectEntry {
        private Object obj;

        /** Instantiates an ObjectEntry wrapper around the specified object*/
        public ObjectEntry(Object obj) {
            this.obj = obj;

        /** Returns true if and only if the objects contained in this wrapper and the other
         * wrapper are the exact same object (same instance, not just equivalent)*/
        public boolean equals(Object other) {
            return obj == ((ObjectEntry)other).obj;

         * Returns the contained object's identityHashCode. Note that identityHashCode values
         * are not guaranteed to be unique from object to object, but the hash code is guaranteed to
         * not change over time for a given instance of an Object.
        public int hashCode() {
            return System.identityHashCode(obj);

I believe that this should ensure unique IDs throughout the lifetime of the program. Note, however, that you probably don't want to use this in a production application because it maintains references to all of the objects for which you generate IDs. This means that any objects for which you create an ID will never be garbage collected.

Since I'm using this for debug purposes, I'm not too concerned with the memory being freed.

You could modify this to allow clearing Objects or removing individual objects if freeing memory is a concern.

Auto increment primary key in SQL Server Management Studio 2012

    Personid int IDENTITY(1,1) PRIMARY KEY,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int

The MS SQL Server uses the IDENTITY keyword to perform an auto-increment feature.

In the example above, the starting value for IDENTITY is 1, and it will increment by 1 for each new record.

Tip: To specify that the "Personid" column should start at value 10 and increment by 5, change it to IDENTITY(10,5).

To insert a new record into the "Persons" table, we will NOT have to specify a value for the "Personid" column (a unique value will be added automatically):

What is the difference between Scope_Identity(), Identity(), @@Identity, and Ident_Current()?

To clarify the problem with @@Identity:

For instance, if you insert a table and that table has triggers doing inserts, @@Identity will return the id from the insert in the trigger (a log_id or something), while scope_identity() will return the id from the insert in the original table.

So if you don't have any triggers, scope_identity() and @@identity will return the same value. If you have triggers, you need to think about what value you'd like.

Where is the Microsoft.IdentityModel dll

In Windows 8.1 64bit, look under C:\Windows\ADFS

SQL Server 2012 column identity increment jumping from 6 to 1000+ on 7th entry

This is all perfectly normal. Microsoft added sequences in SQL Server 2012, finally, i might add and changed the way identity keys are generated. Have a look here for some explanation.

If you want to have the old behaviour, you can:

  1. use trace flag 272 - this will cause a log record to be generated for each generated identity value. The performance of identity generation may be impacted by turning on this trace flag.
  2. use a sequence generator with the NO CACHE setting (

Firebase: how to generate a unique numeric ID for key?

Use transactions and keep a number in the database somewhere that you can increase by one. This way you can get a nice numeric and simple id.

Why does comparing strings using either '==' or 'is' sometimes produce a different result?

From my limited experience with python, is is used to compare two objects to see if they are the same object as opposed to two different objects with the same value. == is used to determine if the values are identical.

Here is a good example:

>>> s1 = u'public'
>>> s2 = 'public'
>>> s1 is s2
>>> s1 == s2

s1 is a unicode string, and s2 is a normal string. They are not the same type, but are the same value.

SQL Server, How to set auto increment after creating a table without data loss?

Yes, you can. Go to Tools > Designers > Table and Designers and uncheck "Prevent Saving Changes That Prevent Table Recreation".

Handling identity columns in an "Insert Into TABLE Values()" statement?

By default, if you have an identity column, you do not need to specify it in the VALUES section. If your table is:


Then you can do:

INSERT INTO MyTbl VALUES ('Joe', '123 State Street, Boston, MA')

This will auto-generate the ID for you, and you don't have to think about it at all. If you SET IDENTITY_INSERT MyTbl ON, you can assign a value to the ID column.

How to change identity column values programmatically?

Very nice question, first we need to on the IDENTITY_INSERT for the specific table, after that run the insert query (Must specify the column name).

Note: After edit the the identity column, don't forget to off the IDENTITY_INSERT. If you not done, you cannot able to Edit the identity column for any other table.

     INSERT Emp_tb_gb_Menu(MenuID) VALUES (68)

ASP.NET MVC 5 - Identity. How to get current ApplicationUser

For MVC 5 just look inside the EnableTwoFactorAuthentication method of ManageController in WebApplication template scaffold, its being done there:

        public async Task<ActionResult> EnableTwoFactorAuthentication()
            await UserManager.SetTwoFactorEnabledAsync(User.Identity.GetUserId(), true);
            var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());
            if (user != null)
                await SignInManager.SignInAsync(user, isPersistent: false, rememberBrowser: false);
            return RedirectToAction("Index", "Manage");

The answer is right there as suggested by Microsoft itself:

var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());

It will have all the additional properties you defined in ApplicationUser class.

typedef fixed length array

To use the array type properly as a function argument or template parameter, make a struct instead of a typedef, then add an operator[] to the struct so you can keep the array like functionality like so:

typedef struct type24 {
  char& operator[](int i) { return byte[i]; }
  char byte[3];
} type24;

type24 x;
x[2] = 'r';
char c = x[2];

Jenkins: Can comments be added to a Jenkinsfile?

You can use block (/***/) or single line comment (//) for each line. You should use "#" in sh command.

Block comment

/*  _x000D_
post {_x000D_
    success {_x000D_
      mail to: "[email protected]", _x000D_
      subject:"SUCCESS: ${currentBuild.fullDisplayName}", _x000D_
      body: "Yay, we passed."_x000D_
    failure {_x000D_
      mail to: "[email protected]", _x000D_
      subject:"FAILURE: ${currentBuild.fullDisplayName}", _x000D_
      body: "Boo, we failed."_x000D_

Single Line

// post {_x000D_
//     success {_x000D_
//       mail to: "[email protected]", _x000D_
//       subject:"SUCCESS: ${currentBuild.fullDisplayName}", _x000D_
//       body: "Yay, we passed."_x000D_
//     }_x000D_
//     failure {_x000D_
//       mail to: "[email protected]", _x000D_
//       subject:"FAILURE: ${currentBuild.fullDisplayName}", _x000D_
//       body: "Boo, we failed."_x000D_
//     }_x000D_
// }

Comment in 'sh' command

        stage('Unit Test') {_x000D_
            steps {_x000D_
                  sh '''_x000D_
                  npm test_x000D_
                  # this is a comment in sh_x000D_

socket programming multiple client to one server

Here is code for Multiple Client to one Server Working Fine .. Give it a try :)

import java.util.logging.Level;
import java.util.logging.Logger;

class Multi extends Thread{
private Socket s=null;
DataInputStream infromClient;
Multi() throws IOException{

Multi(Socket s) throws IOException{
    infromClient = new DataInputStream(s.getInputStream());
public void run(){  

    String SQL=new String();
    try {
        SQL = infromClient.readUTF();
    } catch (IOException ex) {
        Logger.getLogger(Multi.class.getName()).log(Level.SEVERE, null, ex);
    System.out.println("Query: " + SQL); 
    try {
        System.out.println("Socket Closing");
    } catch (IOException ex) {
        Logger.getLogger(Multi.class.getName()).log(Level.SEVERE, null, ex);
public class Server {

public static void main(String args[]) throws IOException, 

        ServerSocket ss=new ServerSocket(11111);
        System.out.println("Server is Awaiting"); 
        Socket s=ss.accept();
        Multi t=new Multi(s);




public class client1 {
   public static void main(String[] arg) {
  try {

     Socket socketConnection = new Socket("", 11111);

     DataOutputStream outToServer = new DataOutputStream(socketConnection.getOutputStream());

     String SQL="I  am  client 1";

  } catch (Exception e) {System.out.println(e); }


public class client2 {
    public static void main(String[] arg) {
  try {

     Socket socketConnection = new Socket("", 11111);

     DataOutputStream outToServer = new DataOutputStream(socketConnection.getOutputStream());

     String SQL="I am  Client 2";

  } catch (Exception e) {System.out.println(e); }

CSS Background Image Not Displaying

I know this doesn't address the exact case of the OP, but for others coming from Google don't forget to try display: block; based on the element type. I had the image in an <i>, but it wasn't appearing...

OS X Terminal UTF-8 issues

My terminal was just acting silly, not printing out åäö. I found (and set) this setting: enter image description here

Under Terminal -> Preferences... -> Profiles -> Advanced.

Seems to have fixed my problem.

I keep getting this error for my simple python program: "TypeError: 'float' object cannot be interpreted as an integer"


for i in range(c/10):

You're creating a float as a result - to fix this use the int division operator:

for i in range(c // 10):

Update Eclipse with Android development tools v. 23

After trying the approaches in other answers without success, I just installed a new bundle from and that worked fine.

Do the following:

  1. As you don't want to re-download all the platforms again, copy the existing one from /OLD_ANDROID_SDK_PATH/sdk/platforms to /NEW_ANDROID_SDK_PATH/sdk/platforms.
  2. When opening the new Eclipse from the recent downloaded bundle, make sure you reuse the previous 'workspace' folder. That will ensure that all your previous settings will be remembered.
  3. After opening the new Eclipse on the previous workspace, please check if the used Android SDK is pointing to the new one (Eclipse preferences -> Android). It might be pointing to the old one, as you've reused the previews workspace settings.

With these steps, you should't have to reconfigure everything, and you won't need to spend time troubleshooting this BUG on this upgrade from Google Developers.

Good luck! ;-)

PostgreSQL: How to change PostgreSQL user password?

I believe the best way to change the password is simply to use:


in the Postgres console.

Per ALTER USER documentation:

Caution must be exercised when specifying an unencrypted password with this command. The password will be transmitted to the server in cleartext, and it might also be logged in the client's command history or the server log. psql contains a command \password that can be used to change a role's password without exposing the cleartext password.

Note: ALTER USER is an alias for ALTER ROLE

How to get the parents of a Python class?

Use bases if you just want to get the parents, use __mro__ (as pointed out by @naught101) for getting the method resolution order (so to know in which order the init's were executed).

Bases (and first getting the class for an existing object):

>>> some_object = "some_text"
>>> some_object.__class__.__bases__

For mro in recent Python versions:

>>> some_object = "some_text"
>>> some_object.__class__.__mro__
(str, object)

Obviously, when you already have a class definition, you can just call __mro__ on that directly:

>>> class A(): pass
>>> A.__mro__
(__main__.A, object)

how to display data values on Chart.js

If you are using the plugin chartjs-plugin-datalabels then the following code options object will help

Make sure you import import 'chartjs-plugin-datalabels'; in your typescript file or add reference to <script src="chartjs-plugin-datalabels.js"></script> in your javascript file.

options: {
    maintainAspectRatio: false,
    responsive: true,
    scales: {
      yAxes: [{
        ticks: {
          beginAtZero: true,
    plugins: {
      datalabels: {
        anchor: 'end',
        align: 'top',
        formatter: Math.round,
        font: {
          weight: 'bold'

postgresql return 0 if returned value is null

(this answer was added to provide shorter and more generic examples to the question - without including all the case-specific details in the original question).

There are two distinct "problems" here, the first is if a table or subquery has no rows, the second is if there are NULL values in the query.

For all versions I've tested, postgres and mysql will ignore all NULL values when averaging, and it will return NULL if there is nothing to average over. This generally makes sense, as NULL is to be considered "unknown". If you want to override this you can use coalesce (as suggested by Luc M).

$ create table foo (bar int);

$ select avg(bar) from foo;

(1 row)

$ select coalesce(avg(bar), 0) from foo;
(1 row)

$ insert into foo values (3);
$ insert into foo values (9);
$ insert into foo values (NULL);
$ select coalesce(avg(bar), 0) from foo;
(1 row)

of course, "from foo" can be replaced by "from (... any complicated logic here ...) as foo"

Now, should the NULL row in the table be counted as 0? Then coalesce has to be used inside the avg call.

$ select coalesce(avg(coalesce(bar, 0)), 0) from foo;
(1 row)

How to swap two variables in JavaScript

You can do this:

var a = 1,
    b = 2,
tmp = a;
a = b;
b = tmp;

For readability and maintainability, this can't be beat (at least in JavaScript). Anybody maintaining the code (including you six months from now) will know exactly what's going on.

Since these are integers, you can also use any number of clever tricks1 to swap without using a third variable. For instance you can use the bitwise xor operator:

let a = 1, b = 2;_x000D_
a = a ^ b;_x000D_
b = a ^ b;_x000D_
a = a ^ b;_x000D_
console.log('a is now:', a);_x000D_
console.log('b is now:', b);

This is called the XOR swap algorithm. Its theory of operation is described in this Wikipedia article.

1"The competent programmer is fully aware of the limited size of his own skull. He therefore approaches his task with full humility, and avoids clever tricks like the plague." — Edsger W. Dijkstra

How to search a Git repository by commit message?

git log --grep=<pattern>
            Limit the commits output to ones with log message that matches the
            specified pattern (regular expression).

Unable to set data attribute using jQuery Data() API

Had the same problem. Since you can still get data using the .data() method, you only have to figure out a way to write to the elements. This is the helper method I use. Like most people have said, you will have to use .attr. I have it replacing any _ with - as I know it does that. I'm not aware of any other characters it replaces...however I have not researched that.

function ExtendElementData(element, object){
    //element is what you want to set data on
    //object is a hash/js-object
    var keys = Object.keys(object);
    for (var i = 0; i < keys.length; i++){
        var key = keys[i];
        $(element).attr('data-'+key.replace("_", "-"), object[key]);

EDIT: 5/1/2017

I found there were still instances where you could not get the correct data using built in methods so what I use now is as follows:

function setDomData(element, object){
    //object is a hash

    var keys = Object.keys(object);
    for (var i = 0; i < keys.length; i++){
        var key = keys[i];
        $(element).attr('data-'+key.replace("_", "-"), object[key]);

function getDomData(element, key){
    var domObject = $(element).get(0);
    var attKeys = Object.keys(domObject.attributes);

    var values = null;
    if (key != null){
        values = $(element).attr('data-' + key);
    } else {
        values = {};

        var keys = [];
        for (var i = 0; i < attKeys.length; i++) {

        for (var i = 0; i < keys.length; i++){
                values[keys[i]] = $(element).attr(keys[i]);
    return values;

jQuery Date Picker - disable past dates

jQuery API documentation - datepicker

The minimum selectable date. When set to null, there is no minimum.

Multiple types supported:

Date: A date object containing the minimum date.
Number: A number of days from today. For example 2 represents two days from today and -1 represents yesterday.
String: A string in the format defined by the dateFormat option, or a relative date.
Relative dates must contain value and period pairs; valid periods are y for years, m for months, w for weeks, and d for days. For example, +1m +7d represents one month and seven days from today.

In order not to display previous dates other than today

$('#datepicker').datepicker({minDate: 0});

how to save DOMPDF generated content to file?

I have just used dompdf and the code was a little different but it worked.

Here it is:

$files = glob("./pdf/include/*.php");
foreach($files as $file) include_once($file);

$html =
      '<p>Put your html here, or generate it with your favourite '.
      'templating system.</p>'.

    $dompdf = new DOMPDF();
    $output = $dompdf->output();
    file_put_contents('Brochure.pdf', $output);

Only difference here is that all of the files in the include directory are included.

Other than that my only suggestion would be to specify a full directory path for writing the file rather than just the filename.

smtp configuration for php mail

PHP's mail() function does not have support for SMTP. You're going to need to use something like the PEAR Mail package.

Here is a sample SMTP mail script:


$from = "Your Name <[email protected]>";
$to = "Their Name <[email protected]>";
$subject = "Subject";
$body = "Lorem ipsum dolor sit amet, consectetur adipiscing elit...";

$host = "";
$username = "smtp_username";
$password = "smtp_password";

$headers = array('From' => $from, 'To' => $to, 'Subject' => $subject);

$smtp = Mail::factory('smtp', array ('host' => $host,
                                     'auth' => true,
                                     'username' => $username,
                                     'password' => $password));

$mail = $smtp->send($to, $headers, $body);

if ( PEAR::isError($mail) ) {
    echo("<p>Error sending mail:<br/>" . $mail->getMessage() . "</p>");
} else {
    echo("<p>Message sent.</p>");

How can I delete a query string parameter in JavaScript?

From what I can see, none of the above can handle normal parameters and array parameters. Here's one that does.

function removeURLParameter(param, url) {
    url = decodeURI(url).split("?");
    path = url.length == 1 ? "" : url[1];
    path = path.replace(new RegExp("&?"+param+"\\[\\d*\\]=[\\w]+", "g"), "");
    path = path.replace(new RegExp("&?"+param+"=[\\w]+", "g"), "");
    path = path.replace(/^&/, "");
    return url[0] + (path.length
        ? "?" + path
        : "");

function addURLParameter(param, val, url) {
    if(typeof val === "object") {
        // recursively add in array structure
        if(val.length) {
            return addURLParameter(
                param + "[]",
                val.splice(-1, 1)[0],
                addURLParameter(param, val, url)
        } else {
            return url;
    } else {
        url = decodeURI(url).split("?");
        path = url.length == 1 ? "" : url[1];
        path += path.length
            ? "&"
            : "";
        path += decodeURI(param + "=" + val);
        return url[0] + "?" + path;

How to use it:

url = location.href;

url = removeURLParameter("sold", url)

url = removeURLParameter("tags", url)

url = addURLParameter("tags", ["single", "promo"], url)

url = addURLParameter("sold", 1, url)

Of course, to update a parameter, just remove then add. Feel free to make a dummy function for it.

What are the rules for casting pointers in C?

Casting pointers is usually invalid in C. There are several reasons:

  1. Alignment. It's possible that, due to alignment considerations, the destination pointer type is not able to represent the value of the source pointer type. For example, if int * were inherently 4-byte aligned, casting char * to int * would lose the lower bits.

  2. Aliasing. In general it's forbidden to access an object except via an lvalue of the correct type for the object. There are some exceptions, but unless you understand them very well you don't want to do it. Note that aliasing is only a problem if you actually dereference the pointer (apply the * or -> operators to it, or pass it to a function that will dereference it).

The main notable cases where casting pointers is okay are:

  1. When the destination pointer type points to character type. Pointers to character types are guaranteed to be able to represent any pointer to any type, and successfully round-trip it back to the original type if desired. Pointer to void (void *) is exactly the same as a pointer to a character type except that you're not allowed to dereference it or do arithmetic on it, and it automatically converts to and from other pointer types without needing a cast, so pointers to void are usually preferable over pointers to character types for this purpose.

  2. When the destination pointer type is a pointer to structure type whose members exactly match the initial members of the originally-pointed-to structure type. This is useful for various object-oriented programming techniques in C.

Some other obscure cases are technically okay in terms of the language requirements, but problematic and best avoided.

How to declare an array of objects in C#

With LINQ, you can transform the array of uninitialized elements into the new collection of created objects with one line of code.

var houses = new GameObject[200].Select(h => new GameObject()).ToArray();

Actually, you can use any other source for this, even generated sequence of integers:

var houses = Enumerable.Repeat(0, 200).Select(h => new GameObject()).ToArray();

However, the first case seems to me more readable, although the type of original sequence is not important.

How to check identical array in most efficient way?

You could compare String representations so:

array1.toString() == array2.toString()
array1.toString() !== array3.toString()

but that would also make

array4 = ['1',2,3,4,5]

equal to array1 if that matters to you

Can an Option in a Select tag carry multiple values?

I was actually wondering this today, and I achieved it by using the php explode function, like this:

HTML Form (in a file I named 'doublevalue.php':

    <form name="car_form" method="post" action="doublevalue_action.php">
            <select name="car" id="car">
                    <option value="">Select Car</option>
                    <option value="BMW|Red">Red BMW</option>
                    <option value="Mercedes|Black">Black Mercedes</option>
            <input type="submit" name="submit" id="submit" value="submit">

PHP action (in a file I named doublevalue_action.php)

            $result = $_POST['car'];
            $result_explode = explode('|', $result);
            echo "Model: ". $result_explode[0]."<br />";
            echo "Colour: ". $result_explode[1]."<br />";

As you can see in the first piece of code, we're creating a standard HTML select box, with 2 options. Each option has 1 value, which has a separator (in this instance, '|') to split the values (in this case, model and colour).

On the action page, I'm exploding the results into an array, then calling each one. As you can see, I've separated and labelled them so you can see the effect this is causing.

I hope this helps someone :)

What is the easiest way to push an element to the beginning of the array?

What about using the unshift method?

ary.unshift(obj, ...) ? ary
Prepends objects to the front of self, moving other elements upwards.

And in use:

irb>> a = [ 0, 1, 2]
=> [0, 1, 2]
irb>> a.unshift('x')
=> ["x", 0, 1, 2]
irb>> a.inspect
=> "["x", 0, 1, 2]"

How to replace string in Groovy

You need to escape the backslash \:

println yourString.replace("\\", "/")

How do I remove version tracking from a project cloned from git?

From root folder run

find . | grep .git

Review the matches and confirm it only contains those files you want to delete and adjust to suit. Once satisfied, run

find . | grep .git | xargs rm -rf

Scrollview can host only one direct child

Wrap all the children inside of another LinearLayout with wrap_content for both the width and the height as well as the vertical orientation.

Convert pyQt UI to python

I'm not sure if PyQt does have a script like this, but after you install PySide there is a script in pythons script directory "". You can use this script to convert a .ui file to a .py file:

python input.ui -o -x

Convert String to Float in Swift

Swift 2.0+

Now with Swift 2.0 you can just use Float(Wage.text) which returns a Float? type. More clear than the below solution which just returns 0.

If you want a 0 value for an invalid Float for some reason you can use Float(Wage.text) ?? 0 which will return 0 if it is not a valid Float.

Old Solution

The best way to handle this is direct casting:

var WageConversion = (Wage.text as NSString).floatValue

I actually created an extension to better use this too:

extension String {
    var floatValue: Float {
        return (self as NSString).floatValue

Now you can just call var WageConversion = Wage.text.floatValue and allow the extension to handle the bridge for you!

This is a good implementation since it can handle actual floats (input with .) and will also help prevent the user from copying text into your input field (12p.34, or even 12.12.41).

Obviously, if Apple does add a floatValue to Swift this will throw an exception, but it may be nice in the mean time. If they do add it later, then all you need to do to modify your code is remove the extension and everything will work seamlessly, since you will already be calling .floatValue!

Also, variables and constants should start with a lower case (including IBOutlets)

Getting the text from a drop-down box

Please try the below this is the easiest way and it works perfectly

var newSkill_Text = document.getElementById("newSkill")[document.getElementById("newSkill").selectedIndex];

T-SQL: Export to new Excel file

This is by far the best post for exporting to excel from SQL:

To quote from user madhivanan,

Apart from using DTS and Export wizard, we can also use this query to export data from SQL Server2000 to Excel

Create an Excel file named testing having the headers same as that of table columns and use these queries

1 Export data to existing EXCEL file from SQL Server table

insert into OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
    'Excel 8.0;Database=D:\testing.xls;', 
    'SELECT * FROM [SheetName$]') select * from SQLServerTable

2 Export data from Excel to new SQL Server table

select * 
into SQLServerTable FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
    'Excel 8.0;Database=D:\testing.xls;HDR=YES', 
    'SELECT * FROM [Sheet1$]')

3 Export data from Excel to existing SQL Server table (edited)

Insert into SQLServerTable Select * FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
    'Excel 8.0;Database=D:\testing.xls;HDR=YES', 
    'SELECT * FROM [SheetName$]')

4 If you dont want to create an EXCEL file in advance and want to export data to it, use

EXEC sp_makewebtask 
    @outputfile = 'd:\testing.xls', 
    @query = 'Select * from Database_name..SQLServerTable', 
    @colheaders =1, 
    @FixedFont=0,@lastupdated=0,@resultstitle='Testing details'

(Now you can find the file with data in tabular format)

5 To export data to new EXCEL file with heading(column names), create the following procedure

create procedure proc_generate_excel_with_columns
    @db_name    varchar(100),
    @table_name varchar(100),   
    @file_name  varchar(100)

--Generate column names as a recordset
declare @columns varchar(8000), @sql varchar(8000), @data_file varchar(100)
    @columns=coalesce(@columns+',','')+column_name+' as '+column_name 
select @columns=''''''+replace(replace(@columns,' as ',''''' as '),',',',''''')

--Create a dummy file to have actual data
select @data_file=substring(@file_name,1,len(@file_name)-charindex('\',reverse(@file_name)))+'\data_file.xls'

--Generate column names in the passed EXCEL file
set @sql='exec master..xp_cmdshell ''bcp " select * from (select '+@columns+') as t" queryout "'+@file_name+'" -c'''

--Generate data in the dummy file
set @sql='exec master..xp_cmdshell ''bcp "select * from '+@db_name+'..'+@table_name+'" queryout "'+@data_file+'" -c'''

--Copy dummy file to passed EXCEL file
set @sql= 'exec master..xp_cmdshell ''type '+@data_file+' >> "'+@file_name+'"'''

--Delete dummy file 
set @sql= 'exec master..xp_cmdshell ''del '+@data_file+''''

After creating the procedure, execute it by supplying database name, table name and file path:

EXEC proc_generate_excel_with_columns 'your dbname', 'your table name','your file path'

Its a whomping 29 pages but that is because others show various other ways as well as people asking questions just like this one on how to do it.

Follow that thread entirely and look at the various questions people have asked and how they are solved. I picked up quite a bit of knowledge just skimming it and have used portions of it to get expected results.

To update single cells

A member also there Peter Larson posts the following: I think one thing is missing here. It is great to be able to Export and Import to Excel files, but how about updating single cells? Or a range of cells?

This is the principle of how you do manage that

update OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
'Excel 8.0;Database=c:\test.xls;hdr=no', 
'SELECT * FROM [Sheet1$b7:b7]') set f1 = -99

You can also add formulas to Excel using this:

update OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
'Excel 8.0;Database=c:\test.xls;hdr=no', 
'SELECT * FROM [Sheet1$b7:b7]') set f1 = '=a7+c7'

Exporting with column names using T-SQL

Member Mladen Prajdic also has a blog entry on how to do this here

References: (btw this is an excellent blog / forum for anyone looking to get more out of SQL Server). For error referencing I used this

Errors that may occur

If you get the following error:

OLE DB provider 'Microsoft.Jet.OLEDB.4.0' cannot be used for distributed queries

Then run this:

sp_configure 'show advanced options', 1;
sp_configure 'Ad Hoc Distributed Queries', 1;

How to make an alert dialog fill 90% of screen size?

After initialize your dialog object and set the content view. Do this and enjoy.

(in the case i am setting 90% to width and 70% to height because width 90% it will be over toolbar )

DisplayMetrics displaymetrics = new DisplayMetrics();
int width = (int) ((int)displaymetrics.widthPixels * 0.9);
int height = (int) ((int)displaymetrics.heightPixels * 0.7);

How do I use Join-Path to combine more than two strings into a file path?

The following approach is more concise than piping Join-Path statements:

$p = "a"; "b", "c", "d" | ForEach-Object -Process { $p = Join-Path $p $_ }

$p then holds the concatenated path 'a\b\c\d'.

(I just noticed that this is the exact same approach as Mike Fair's, sorry.)

Using jQuery Fancybox or Lightbox to display a contact form

Greybox cannot handle forms inside it on its own. It requires a forms plugin. No iframes or external html files needed. Don't forget to download the greybox.css file too as the page misses that bit out.

Kiss Jquery UI goodbye and a lightbox hello. You can get it here.

How does `scp` differ from `rsync`?

scp is best for one file.
OR a combination of tar & compression for smaller data sets like source code trees with small resources (ie: images, sqlite etc).

Yet, when you begin dealing with larger volumes say:

  • media folders (40 GB)
  • database backups (28 GB)
  • mp3 libraries (100 GB)

It becomes impractical to build a zip/tar.gz file to transfer with scp at this point do to the physical limits of the hosted server.

As an exercise, you can do some gymnastics like piping tar into ssh and redirecting the results into a remote file. (saving the need to build a swap or temporary clone aka zip or tar.gz)


rsync simplify's this process and allows you to transfer data without consuming any additional disc space.


Continuous (cron?) updates use minimal changes vs full cloned copies speed up large data migrations over time.

scp == small scale (with room to build compressed files on the same drive)
rsync == large scale (with the necessity to backup large data and no room left)

Graphviz: How to go from .dot to a graph?

You can also output your file in xdot format, then render it in a browser using canviz, a JavaScript library.

Canviz on

To see an example, there is a "Canviz Demo" link on the page above as of November 2, 2014.

How to hide scrollbar in Firefox?

I used this and it worked.

html {
scrollbar-width: none;

Note: User Agents must apply any scrollbar-width value set on the root element to the viewport.

grep regex whitespace behavior

This looks like a behavior difference in the handling of \s between grep 2.5 and newer versions (a bug in old grep?). I confirm your result with grep 2.5.4, but all four of your greps do work when using grep 2.6.3 (Ubuntu 10.10).


GNU grep 2.5.4
echo "foo bar" | grep "\s"
   (doesn't match)


GNU grep 2.6.3
echo "foo bar" | grep "\s"
foo bar

Probably less trouble (as \s is not documented):

Both GNU greps
echo "foo bar" | grep "[[:space:]]"
foo bar

My advice is to avoid using \s ... use [ \t]* or [[:space:]] or something like it instead.


You can also try:

create table new_table as
select * from table1
select * from table2

Vue.js unknown custom element

I had the same error

[Vue warn]: Unknown custom element: - did you register the component correctly? For recursive components, make sure to provide the "name" option.

however, I totally forgot to run npm install && npm run dev to compiling the js files.

maybe this helps newbies like me.

How to get absolute value from double - c-language

I have found that using cabs(double), cabsf(float), cabsl(long double), __cabsf(float), __cabs(double), __cabsf(long double) is the solution

In the shell, what does " 2>&1 " mean?

unix_commands 2>&1

This is used to print errors to the terminal.

The following illustrates the process

  • When errors are produced, they are written into the standard error memory address &2 "buffer", from which the standard error stream 2 references.
  • When output is produced, it is written into the standard output memory address &1 "buffer", from which the standard output stream 1 references.

So take the unix_commands standard error stream 2, and redirect > the stream (of errors) to the standard output memory address &1, so that they will be streamed to the terminal and printed.

How to create a drop-down list?

You can create spinner by these simple steps

first create spinner in xml


now create string arary in values

 <string-array name="itemselect">

now initialized in java file

public class MemberCart_Activity extends AppCompatActivity {

Spinner select;
protected void onCreate(Bundle savedInstanceState) {

 ArrayAdapter<String> myadapter=new ArrayAdapter<String>(Main_Activity.this,android.R.layout.simple_list_item_1,getResources().getStringArray(R.array.itemselect));

Perl - Multiple condition if statement without duplicating code?

I don't recommend storing passwords in a script, but this is a way to what you indicate:

use 5.010;
my %user_table = ( tom => '123!', frank => '321!' );

say ( $user_table{ $name } eq $password ? 'You have gained access.'
    :                                     'Access denied!'

Any time you want to enforce an association like this, it's a good idea to think of a table, and the most common form of table in Perl is the hash.

Visual Studio: How to show Overloads in IntelliSense?

I know this is an old post, but for the newbies like myself who still hit this page this might be useful. when you hover on a method you get a non clickable info-box whereas if you just write a comma in the method parenthesis the IntelliSense will offer you the beloved info-box with the clickable arrows.

Turn off enclosing <p> tags in CKEditor 3.0

MAKE THIS YOUR config.js file code

CKEDITOR.editorConfig = function( config ) {

   //   config.enterMode = 2; //disabled <p> completely
        config.enterMode = CKEDITOR.ENTER_BR // pressing the ENTER KEY input <br/>
        config.shiftEnterMode = CKEDITOR.ENTER_P; //pressing the SHIFT + ENTER KEYS input <p>
        config.autoParagraph = false; // stops automatic insertion of <p> on focus

Django Admin - change header 'Django administration' text

Update: If you are using Django 1.7+, see the answer below.

Original answer from 2011: You need to create your own admin base_site.html template to do this. The easiest way is to create the file:


This should be a copy of the original base_site.html, except putting in your custom title:

{% block branding %}
<h1 id="site-name">{% trans 'my cool admin console' %}</h1>
{% endblock %}

For this to work, you need to have the correct settings for your project, namely in

  • Make sure /projectdir/templates/ is added into TEMPLATE_DIRS.
  • Make sure django.template.loaders.filesystem.Loader is added into TEMPLATE_LOADERS.

See docs for more information on

Why should I use IHttpActionResult instead of HttpResponseMessage?

// this will return HttpResponseMessage as IHttpActionResult
return ResponseMessage(httpResponseMessage); 

Java 8 Lambda function that throws exception?

This is not specific to Java 8. You are trying to compile something equivalent to:

interface I {
    void m();
class C implements I {
    public void m() throws Exception {} //can't compile

Unrecognized attribute 'targetFramework'. Note that attribute names are case-sensitive

for IIS 7 try according to the given picture ... mark me helpful if it works for you.

enter image description here

How to determine whether an object has a given property in JavaScript

Why not simply:

if (typeof myObject.myProperty == "undefined") alert("myProperty is not defined!");

Or if you expect a specific type:

if (typeof myObject.myProperty != "string") alert("myProperty has wrong type or does not exist!");

appending array to FormData and send via AJAX

Typescript version:

export class Utility {      
    public static convertModelToFormData(model: any, form: FormData = null, namespace = ''): FormData {
        let formData = form || new FormData();
        let formKey;

        for (let propertyName in model) {
            if (!model.hasOwnProperty(propertyName) || !model[propertyName]) continue;
            let formKey = namespace ? `${namespace}[${propertyName}]` : propertyName;
            if (model[propertyName] instanceof Date)
                formData.append(formKey, model[propertyName].toISOString());
            else if (model[propertyName] instanceof Array) {
                model[propertyName].forEach((element, index) => {
                    const tempFormKey = `${formKey}[${index}]`;
                    this.convertModelToFormData(element, formData, tempFormKey);
            else if (typeof model[propertyName] === 'object' && !(model[propertyName] instanceof File))
                this.convertModelToFormData(model[propertyName], formData, formKey);
                formData.append(formKey, model[propertyName].toString());
        return formData;


let formData = Utility.convertModelToFormData(model);

Swift 3 - Comparing Date objects

SWIFT 3: Don't know if this is what you're looking for. But I compare a string to a current timestamp to see if my string is older that now.

func checkTimeStamp(date: String!) -> Bool {
        let dateFormatter: DateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
        dateFormatter.locale = Locale(identifier:"en_US_POSIX")
        let datecomponents = date)

        let now = Date()

        if (datecomponents! >= now) {
            return true
        } else {
            return false

To use it:

if (checkTimeStamp(date:"2016-11-21 12:00:00") == false) {
    // Do something

Repeat each row of data.frame the number of times specified in a column

In case you have to do this operation on very large data.frames I would recommend converting it into a data.table and use the following, which should run much faster:

dt <- data.table(df)
dt.expanded <- dt[ ,list(freq=rep(1,freq)),by=c("var1","var2")]
dt.expanded[ ,freq := NULL]

See how much faster this solution is:

df <- data.frame(var1=1:2e3, var2=1:2e3, freq=1:2e3)
system.time(df.exp <- df[rep(row.names(df), df$freq), 1:2])
##    user  system elapsed 
##    4.57    0.00    4.56
dt <- data.table(df)
system.time(dt.expanded <- dt[ ,list(freq=rep(1,freq)),by=c("var1","var2")])
##    user  system elapsed 
##    0.05    0.01    0.06

Drawing in Java using Canvas

The following should work:

public static void main(String[] args)
    final String title = "Test Window";
    final int width = 1200;
    final int height = width / 16 * 9;

    //Creating the frame.
    JFrame frame = new JFrame(title);

    frame.setSize(width, height);

    //Creating the canvas.
    Canvas canvas = new Canvas();

    canvas.setSize(width, height);

    //Putting it all together.


    boolean running = true;

    BufferStrategy bufferStrategy;
    Graphics graphics;

    while (running) {
        bufferStrategy = canvas.getBufferStrategy();
        graphics = bufferStrategy.getDrawGraphics();
        graphics.clearRect(0, 0, width, height);

        graphics.drawString("This is some text placed in the top left corner.", 5, 15);;

Get cursor position (in characters) within a text Input field

const inpT = document.getElementById("text-box");_x000D_
const inpC = document.getElementById("text-box-content");_x000D_
// swch gets  inputs ._x000D_
var swch;_x000D_
// swch  if corsur is active in inputs defaulte is false ._x000D_
var isSelect = false;_x000D_
var crnselect;_x000D_
// on focus_x000D_
function setSwitch(e) {_x000D_
  swch = e;_x000D_
  isSelect = true;_x000D_
  console.log("set Switch: " + isSelect);_x000D_
// on click ev_x000D_
function setEmoji() {_x000D_
  if (isSelect) {_x000D_
    console.log("emoji added :)");_x000D_
    swch.value += ":)";_x000D_
    swch.setSelectionRange(2,2 );_x000D_
    isSelect = true;_x000D_
// on not selected on input . _x000D_
function onout() {_x000D_
  // ??????  ??? ?? ?? _x000D_
  crnselect = inpC.selectionStart;_x000D_
  // return input select not active after 200 ms ._x000D_
  var len = swch.value.length;_x000D_
  setTimeout(() => {_x000D_
   (len == swch.value.length)? isSelect = false:isSelect = true;_x000D_
  }, 200);_x000D_
<h1> Try it !</h1>_x000D_
  <input type="text" onfocus = "setSwitch(this)" onfocusout = "onout()" id="text-box" size="20" value="title">_x000D_
  <input type="text" onfocus = "setSwitch(this)"  onfocusout = "onout()"  id="text-box-content" size="20" value="content">_x000D_
<button onclick="setEmoji()">emogi :) </button>

How can I use SUM() OVER()

Query would be like this:

SELECT ID, AccountID, Quantity, 
       SUM(Quantity) OVER (PARTITION BY AccountID ) AS TopBorcT 

       FROM #Empl ORDER BY AccountID

Partition by works like group by. Here we are grouping by AccountID so sum would be corresponding to AccountID.

First first case, AccountID = 1 , then sum(quantity) = 10 + 5 + 2 => 17 & For AccountID = 2, then sum(Quantity) = 7+3 => 10

so result would appear like attached snapshot.

What is the difference between Html.Hidden and Html.HiddenFor

Html.Hidden('name', 'value') creates a hidden tag with name = 'name' and value = 'value'.

Html.HiddenFor(x => x.nameProp) creates a hidden tag with a name = 'nameProp' and value = x.nameProp.

At face value these appear to do similar things, with one just more convenient than the other. But its actual value is for model binding. When MVC tries to associate the html to the model, it needs to have the name of the property, and for Html.Hidden, we chose 'name', and not 'nameProp', and thus the binding wouldn't work. You'd have to have a custom binding object, or get the values from the form data. If you are redisplaying the page, you'd have to set the model to the values again.

So you can use Html.Hidden, but if you get the name wrong, or if you change the property name in the model, the auto binding will fail when you submit the form. But by using a type checked expression, you'll get code completion, and when you change the property name, you will get a compile time error. And then you are guaranteed to have the correct name in the form.

One of the better features of MVC.

How to make certain text not selectable with CSS

Use a simple background image for the textarea suffice.


<div onselectstart="return false">your text</div>

Speed comparison with Project Euler: C vs Python vs Erlang vs Haskell

Question 1: Do erlang, python and haskell loose speed due to using arbitrary length integers or don't they as long as the values are less than MAXINT?

This is unlikely. I cannot say much about Erlang and Haskell (well, maybe a bit about Haskell below) but I can point a lot of other bottlenecks in Python. Every time the program tries to execute an operation with some values in Python, it should verify whether the values are from the proper type, and it costs a bit of time. Your factorCount function just allocates a list with range (1, isquare + 1) various times, and runtime, malloc-styled memory allocation is way slower than iterating on a range with a counter as you do in C. Notably, the factorCount() is called multiple times and so allocates a lot of lists. Also, let us not forget that Python is interpreted and the CPython interpreter has no great focus on being optimized.

EDIT: oh, well, I note that you are using Python 3 so range() does not return a list, but a generator. In this case, my point about allocating lists is half-wrong: the function just allocates range objects, which are inefficient nonetheless but not as inefficient as allocating a list with a lot of items.

Question 2: Why is haskell so slow? Is there a compiler flag that turns off the brakes or is it my implementation? (The latter is quite probable as haskell is a book with seven seals to me.)

Are you using Hugs? Hugs is a considerably slow interpreter. If you are using it, maybe you can get a better time with GHC - but I am only cogitating hypotesis, the kind of stuff a good Haskell compiler does under the hood is pretty fascinating and way beyond my comprehension :)

Question 3: Can you offer me some hints how to optimize these implementations without changing the way I determine the factors? Optimization in any way: nicer, faster, more "native" to the language.

I'd say you are playing an unfunny game. The best part of knowing various languages is to use them the most different way possible :) But I digress, I just do not have any recommendation for this point. Sorry, I hope someone can help you in this case :)

Question 4: Do my functional implementations permit LCO and hence avoid adding unnecessary frames onto the call stack?

As far as I remember, you just need to make sure that your recursive call is the last command before returning a value. In other words, a function like the one below could use such optimization:

def factorial(n, acc=1):
    if n > 1:
        acc = acc * n
        n = n - 1
        return factorial(n, acc)
        return acc

However, you would not have such optimization if your function were such as the one below, because there is an operation (multiplication) after the recursive call:

def factorial2(n):
    if n > 1:
        f = factorial2(n-1)
        return f*n
        return 1

I separated the operations in some local variables for make it clear which operations are executed. However, the most usual is to see these functions as below, but they are equivalent for the point I am making:

def factorial(n, acc=1):
    if n > 1:
        return factorial(n-1, acc*n)
        return acc

def factorial2(n):
    if n > 1:
        return n*factorial(n-1)
        return 1

Note that it is up to the compiler/interpreter to decide if it will make tail recursion. For example, the Python interpreter does not do it if I remember well (I used Python in my example only because of its fluent syntax). Anyway, if you find strange stuff such as factorial functions with two parameters (and one of the parameters has names such as acc, accumulator etc.) now you know why people do it :)

display html page with node.js

but it ONLY shows the index.html file and NOTHING attached to it, so no images, no effects or anything that the html file should display.

That's because in your program that's the only thing that you return to the browser regardless of what the request looks like.

You can take a look at a more complete example that will return the correct files for the most common web pages (HTML, JPG, CSS, JS) in here

Also, take a look at this blog post that I wrote on how to get started with node. I think it might clarify a few things for you:

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference

it sometimes occurs when we use a custom adapter in any activity of fragment . and we return null object i.e null view so the activity gets confused which view to load , so that is why this exception occurs

shows the position where to change the view

"SetPropertiesRule" warning message when starting Tomcat from Eclipse

I respect all the solutions given here.

But what I came to know after reading all these, we haven't observed that on which folder the struts.xml file or any configuration file which is necessary for the web application.


  1. copy the struts.xml file to the src folder of our project.
  2. click "file-->save all" in eclipse and go click "project-->clean".
  3. restart the server.

Hope the problem solved.

Can I call a constructor from another constructor (do constructor chaining) in C++?

I believe you can call a constructor from a constructor. It will compile and run. I recently saw someone do this and it ran on both Windows and Linux.

It just doesn't do what you want. The inner constructor will construct a temporary local object which gets deleted once the outer constructor returns. They would have to be different constructors as well or you would create a recursive call.


How to return multiple objects from a Java method?

All possible solutions will be a kludge (like container objects, your HashMap idea, “multiple return values” as realized via arrays). I recommend regenerating the comma-separated list from the returned List. The code will end up being a lot cleaner.

Entity Framework Join 3 Tables

This is untested, but I believe the syntax should work for a lambda query. As you join more tables with this syntax you have to drill further down into the new objects to reach the values you want to manipulate.

var fullEntries = dbContext.tbl_EntryPoint
        entryPoint => entryPoint.EID,
        entry => entry.EID,
        (entryPoint, entry) => new { entryPoint, entry }
        combinedEntry => combinedEntry.entry.TID,
        title => title.TID,
        (combinedEntry, title) => new 
            UID = combinedEntry.entry.OwnerUID,
            TID = combinedEntry.entry.TID,
            EID = combinedEntry.entryPoint.EID,
            Title = title.Title
    .Where(fullEntry => fullEntry.UID == user.UID)

MySQL - Make an existing Field Unique

If you also want to name the constraint, use this:

  ADD CONSTRAINT constraintName 
    UNIQUE (columnName);

What is a NullReferenceException, and how do I fix it?

Another scenario is when you cast a null object into a value type. For example, the code below:

object o = null;
DateTime d = (DateTime)o;

It will throw a NullReferenceException on the cast. It seems quite obvious in the above sample, but this can happen in more "late-binding" intricate scenarios where the null object has been returned from some code you don't own, and the cast is for example generated by some automatic system.

One example of this is this simple ASP.NET binding fragment with the Calendar control:

<asp:Calendar runat="server" SelectedDate="<%#Bind("Something")%>" />

Here, SelectedDate is in fact a property - of DateTime type - of the Calendar Web Control type, and the binding could perfectly return something null. The implicit ASP.NET Generator will create a piece of code that will be equivalent to the cast code above. And this will raise a NullReferenceException that is quite difficult to spot, because it lies in ASP.NET generated code which compiles fine...

How to make/get a multi size .ico file?

What i do is to prepare a 512x512 PNG, the Alpha Channel is good for rounded corners or drop shadows, then I upload it to this site, and for free then it returns me a 6 sizes .ico file with 256x256, 128x128, 64x64, 48x48, 32x32 and 16x16 sizes.

Refresh Fragment at reload

Make use of onResume method... both on the fragment activity and the activity holding the fragment.

Calling an API from SQL Server stored procedure

I worked so much, I hope my effort might help you out.

Just paste this into your SSMS and press F5:

Declare @Object as Int;
DECLARE @hr  int
Declare @json as table(Json_Table nvarchar(max))

Exec @hr=sp_OACreate 'MSXML2.ServerXMLHTTP.6.0', @Object OUT;
IF @hr <> 0 EXEC sp_OAGetErrorInfo @Object
Exec @hr=sp_OAMethod @Object, 'open', NULL, 'get',
                 '[out:json];area[name=%22Auckland%22]-%3E.a;(node(area.a)[amenity=cinema];way(area.a)[amenity=cinema];rel(area.a)[amenity=cinema];);out;', --Your Web Service Url (invoked)
IF @hr <> 0 EXEC sp_OAGetErrorInfo @Object
Exec @hr=sp_OAMethod @Object, 'send'
IF @hr <> 0 EXEC sp_OAGetErrorInfo @Object
Exec @hr=sp_OAMethod @Object, 'responseText', @json OUTPUT
IF @hr <> 0 EXEC sp_OAGetErrorInfo @Object

INSERT into @json (Json_Table) exec sp_OAGetProperty @Object, 'responseText'
-- select the JSON string
select * from @json
-- Parse the JSON string
SELECT * FROM OPENJSON((select * from @json), N'$.elements')
WITH (   
      [type] nvarchar(max) N'$.type'   ,
      [id]   nvarchar(max) N'$.id',
      [lat]   nvarchar(max) N'$.lat',
      [lon]   nvarchar(max) N'$.lon',
      [amenity]   nvarchar(max) N'$.tags.amenity',
      [name]   nvarchar(max) N'$'     
EXEC sp_OADestroy @Object

This query will give you 3 results:

1. Catch the error in case something goes wrong (don't panic, it will always show you an error above 4000 characters because NVARCHAR(MAX) can only store till 4000 characters)

2. Put the JSON into a string (which is what we want)

3. BONUS: parse the JSON and nicely store the data into a table (how cool is that?)

enter image description here

Android Webview - Completely Clear the Cache

Make sure you use below method for the form data not be displayed as autopop when clicked on input fields.


How to access the GET parameters after "?" in Express?

In my case with the given code, I was able to parse the value of the passed parameter in this way.

const express = require('express');
const bodyParser = require('body-parser');

const app = express(); 
app.use(bodyParser.urlencoded({ extended: false }));
let val1= req.body.par1;
let val2 = req.body.par2;

Formatting a number with leading zeros in PHP

$no_of_digit = 10;
$number = 123;

$length = strlen((string)$number);
for($i = $length;$i<$no_of_digit;$i++)
    $number = '0'.$number;

echo $number; ///////  result 0000000123

Can I use break to exit multiple nested 'for' loops?

Breaking out of a for-loop is a little strange to me, since the semantics of a for-loop typically indicate that it will execute a specified number of times. However, it's not bad in all cases; if you're searching for something in a collection and want to break after you find it, it's useful. Breaking out of nested loops, however, isn't possible in C++; it is in other languages through the use of a labeled break. You can use a label and a goto, but that might give you heartburn at night..? Seems like the best option though.

How do I create delegates in Objective-C?

Here is a simple method to create delegates

Create Protocol in .h file. Make sure that is defined before the protocol using @class followed by the name of the UIViewController < As the protocol I am going to use is UIViewController class>.

Step : 1 : Create a new class Protocol named "YourViewController" which will be the subclass of UIViewController class and assign this class to the second ViewController.

Step : 2 : Go to the "YourViewController" file and modify it as below:

#import <UIKit/UIkit.h>
@class YourViewController;

@protocol YourViewController Delegate <NSObject>

-(void)defineDelegateMethodName: (YourViewController *) controller;

-(BOOL)delegateMethodReturningBool: (YourViewController *) controller;

  @interface YourViewController : UIViewController

  //Since the property for the protocol could be of any class, then it will be marked as a type of id.

  @property (nonatomic, weak) id< YourViewController Delegate> delegate;


The methods defined in the protocol behavior can be controlled with @optional and @required as part of the protocol definition.

Step : 3 : Implementation of Delegate

    #import "delegate.h"

   @interface YourDelegateUser ()

   @implementation YourDelegateUser

   - (void) variousFoo {
      YourViewController *controller = [[YourViewController alloc] init];
      controller.delegate = self;

   -(void)defineDelegateMethodName: (YourViewController *) controller {
      // handle the delegate being called here

   -(BOOL)delegateMethodReturningBool: (YourViewController *) controller {
      // handle the delegate being called here
      return YES;


//test whether the method has been defined before you call it

 - (void) someMethodToCallDelegate {
     if ([[self delegate] respondsToSelector:@selector(defineDelegateMethodName:)]) {
           [self.delegate delegateMethodName:self]; 

How to append to New Line in Node.js

Use the os.EOL constant instead.

var os = require("os");

function processInput ( text ) 
{'H://log.txt', 'a', 666, function( e, id ) {
   fs.write( id, text + os.EOL, null, 'utf8', function(){
    fs.close(id, function(){
     console.log('file is updated');

SQL ORDER BY date problem

try this

Order by Convert(datetime,@date) desc

jquery click event not firing?

Is this markup added to the DOM asynchronously? You will need to use live in that case:

NOTE: .live has been deprecated and removed in the latest versions of jQuery (for good reason). Please refer to the event delegation strategy below for usage and solution.

        $('.play_navigation a').live('click', function(){
            console.log("this is the click");
            return false;

The fact that you are able to re-run your script block and have it work tells me that for some reason the elements weren't available at the time of binding or the binding was removed at some point. If the elements weren't there at bind-time, you will need to use live (or event delegation, preferably). Otherwise, you need to check your code for something else that would be removing the binding.

Using jQuery 1.7 event delegation:

$(function () {

    $('.play_navigation').on('click', 'a', function (e) {
        console.log('this is the click');


You can also delegate events up to the document if you feel that you would like to bind the event before the document is ready (note that this also causes jQuery to examine every click event to determine if the element matches the appropriate selector):

$(document).on('click', '.play_navigation a', function (e) {
    console.log('this is the click');

How to check type of files without extensions in python?

import subprocess
p = sub.Popen('file yourfile.txt', stdout=sub.PIPE, stderr=sub.PIPE)
output, errors = p.communicate()

As Steven pointed out, subprocess is the way. You can get the command output by the way above as this post said

jquery select option click handler

You want the 'change' event handler, instead of 'click'.

    var value = $(this).val();

Creating a daemon in Linux

A daemon is just a process in the background. If you want to start your program when the OS boots, on linux, you add your start command to /etc/rc.d/rc.local (run after all other scripts) or /etc/

On windows, you make a service, register the service, and then set it to start automatically at boot in administration -> services panel.

Java balanced expressions check {[()]}

public class StackProb {

public static void main(String[] args) {

    Scanner sc = new Scanner(;
    List<Boolean> list = new ArrayList<>();

    while (sc.hasNextLine()) {
        String s=sc.nextLine();
        if(!s.isEmpty()) {
        }else {

    for (int i = 0; i < list.size(); i++) {
        System.out.println(list.get(i) + " ");


private static boolean isBalanced(String s) {
    boolean res = false;
    Stack<Character> stack = new Stack();
    int countA = 0;
    int countB = 0;
    for (int i = 0; i < s.length(); i++) {

        if(s.charAt(i)=='{' || s.charAt(i)=='(' || s.charAt(i)=='[') {


        if(s.charAt(i)=='}' || s.charAt(i)==')' || s.charAt(i)==']') {


        if(stack.firstElement()=='}' || stack.firstElement()==')' || stack.firstElement()==']') {

    if(countA==countB) {
        return true;
    return false;



Check if an apt-get package is installed and then install it if it's not on Linux

which <command>
if [ $? == 1 ]; then
    <pkg-manager> -y install <command>

A column-vector y was passed when a 1d array was expected

Y = y.values[:,0]

Y - formated_train_y

y - train_y

Pass variables between two PHP pages without using a form or the URL of page

Have you tried adding both to $_SESSION?

Then at the top of your page2.php just add:


Rounding to 2 decimal places in SQL

Try this...

SELECT TO_CHAR(column_name,'99G999D99MI')
as format_column

What's the difference between "static" and "static inline" function?

From my experience with GCC I know that static and static inline differs in a way how compiler issue warnings about unused functions. More precisely when you declare static function and it isn't used in current translation unit then compiler produce warning about unused function, but you can inhibit that warning with changing it to static inline.

Thus I tend to think that static should be used in translation units and benefit from extra check compiler does to find unused functions. And static inline should be used in header files to provide functions that can be in-lined (due to absence of external linkage) without issuing warnings.

Unfortunately I cannot find any evidence for that logic. Even from GCC documentation I wasn't able to conclude that inline inhibits unused function warnings. I'd appreciate if someone will share links to description of that.

live output from subprocess command

All of the above solutions I tried failed either to separate stderr and stdout output, (multiple pipes) or blocked forever when the OS pipe buffer was full which happens when the command you are running outputs too fast (there is a warning for this on python poll() manual of subprocess). The only reliable way I found was through select, but this is a posix-only solution:

import subprocess
import sys
import os
import select
# returns command exit status, stdout text, stderr text
# rtoutput: show realtime output while running
def run_script(cmd,rtoutput=0):
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    poller = select.poll()
    poller.register(p.stdout, select.POLLIN)
    poller.register(p.stderr, select.POLLIN)

    while sum(fdhup.values()) < len(fdhup):
            r = poller.poll(1)
        except select.error, err:
            if err.args[0] != EINTR:
        for fd, flags in r:
            if flags & (select.POLLIN | select.POLLPRI):
                c =, 1024)
                if rtoutput:
                if fd == p.stderr.fileno():
    return p.poll(), coutput.strip(), cerror.strip()

Create random list of integers in Python

All the random methods end up calling random.random() so the best way is to call it directly:

[int(1000*random.random()) for i in xrange(10000)]

For example,

  • random.randint calls random.randrange.
  • random.randrange has a bunch of overhead to check the range before returning istart + istep*int(self.random() * n).

NumPy is much faster still of course.

PostgreSQL column 'foo' does not exist

the problem occurs because of the name of column is in camel case internally it wraps it in " "(double quotes) to solve this, at the time of inserting values in table use single quotes ('')

e.g. insert into schema_name.table_name values(' ',' ',' ');

How to echo in PHP, HTML tags

This will also work fine with double quotes. To echo any html_tag with double quotes we just need to remember one thing, Do not use any other double quotes(") in the middle.

    echo "
        <h3><a href=''>First</a></h3>
        <div>Lorem ipsum dolor sit amet.</div>

Notice here the link inside the PHP echo is enclosed within the single quotes. This is the precaution you should take while using the double quotes for this purpose.

How to draw a graph in PHP?

You can use google's chart api to generate charts.

how to convert object into string in php

Use the casting operator (string)$yourObject;

Return 0 if field is null in MySQL

You can use coalesce(column_name,0) instead of just column_name. The coalesce function returns the first non-NULL value in the list.

I should mention that per-row functions like this are usually problematic for scalability. If you think your database may get to be a decent size, it's often better to use extra columns and triggers to move the cost from the select to the insert/update.

This amortises the cost assuming your database is read more often than written (and most of them are).

iPhone system font

The default font for iOS is San Francisco . You can refer the link for further details

Connect to mysql in a docker container from the host

  • docker run -e MYSQL_ROOT_PASSWORD=pass --name sql-db -p 3306:3306 mysql

  • docker exec -it sql-db bash

  • mysql -u root -p

Renaming column names of a DataFrame in Spark Scala

Sometime we have the column name is below format in SQLServer or MySQL table

Ex  : Account Number,customer number

But Hive tables do not support column name containing spaces, so please use below solution to rename your old column names.


val renamedColumns = => df(c).as(c.replaceAll(" ", "_").toLowerCase()))
df = _*)

Java correct way convert/cast object to Double

In Java version prior to 1.7 you cannot cast object to primitive type

double d = (double) obj;

You can cast an Object to a Double just fine

Double d = (Double) obj;

Beware, it can throw a ClassCastException if your object isn't a Double

How to create a temporary directory?

My favorite one-liner for this is

cd $(mktemp -d)

jQuery find element by data attribute value

You can also use .filter()


Set language for syntax highlighting in Visual Studio Code

Syntax Highlighting for custom file extension

Any custom file extension can be associated with standard syntax highlighting with custom files association in User Settings as follows.

Changing File Association settings for permanent Syntax Highlighting

Note that this will be a permanent setting. In order to set for the current session alone, type in the preferred language in Select Language Mode box (without changing file association settings)

Installing new Syntax Package

If the required syntax package is not available by default, you can add them via the Extension Marketplace (Ctrl+Shift+X) and search for the language package.

You can further reproduce the above steps to map the file extensions with the new syntax package.

Change a Git remote HEAD to point to something besides master

If you have access to the remote repo from a shell, just go into the .git (or the main dir if its a bare repo) and change the HEAD file to point to the correct head. For example, by default it always contains 'refs: refs/heads/master', but if you need foo to be the HEAD instead, just edit the HEAD file and change the contents to 'refs: refs/heads/foo'.

When to use cla(), clf() or close() for clearing a plot in matplotlib?

They all do different things, since matplotlib uses a hierarchical order in which a figure window contains a figure which may consist of many axes. Additionally, there are functions from the pyplot interface and there are methods on the Figure class. I will discuss both cases below.

pyplot interface

pyplot is a module that collects a couple of functions that allow matplotlib to be used in a functional manner. I here assume that pyplot has been imported as import matplotlib.pyplot as plt. In this case, there are three different commands that remove stuff:

plt.cla() clears an axes, i.e. the currently active axes in the current figure. It leaves the other axes untouched.

plt.clf() clears the entire current figure with all its axes, but leaves the window opened, such that it may be reused for other plots.

plt.close() closes a window, which will be the current window, if not specified otherwise.

Which functions suits you best depends thus on your use-case.

The close() function furthermore allows one to specify which window should be closed. The argument can either be a number or name given to a window when it was created using figure(number_or_name) or it can be a figure instance fig obtained, i.e., usingfig = figure(). If no argument is given to close(), the currently active window will be closed. Furthermore, there is the syntax close('all'), which closes all figures.

methods of the Figure class

Additionally, the Figure class provides methods for clearing figures. I'll assume in the following that fig is an instance of a Figure:

fig.clf() clears the entire figure. This call is equivalent to plt.clf() only if fig is the current figure.

fig.clear() is a synonym for fig.clf()

Note that even del fig will not close the associated figure window. As far as I know the only way to close a figure window is using plt.close(fig) as described above.

What is the simplest way to convert array to vector?

One simple way can be the use of assign() function that is pre-defined in vector class.



vector<int> v;
v.assign(array, array+5); // 5 is size of array.

Parsing a CSV file using NodeJS

fs = require('fs');
fs.readFile('FILENAME WITH PATH','utf8', function(err,content){
    console.log('error occured ' +JSON.stringify(err));
 console.log('Fileconetent are ' + JSON.stringify(content));

Twitter Bootstrap - borders

If you look at Twitter's own container-app.html demo on GitHub, you'll get some ideas on using borders with their grid.

For example, here's the extracted part of the building blocks to their 940-pixel wide 16-column grid system:

.row {
    zoom: 1;
    margin-left: -20px;

.row > [class*="span"] {
    display: inline;
    float: left;
    margin-left: 20px;

.span4 {
    width: 220px;

To allow for borders on specific elements, they added embedded CSS to the page that reduces matching classes by enough amount to account for the border(s).

Screenshot of Example Page

For example, to allow for the left border on the sidebar, they added this CSS in the <head> after the the main <link href="../bootstrap.css" rel="stylesheet">.

.content .span4 {
    margin-left: 0;
    padding-left: 19px;
    border-left: 1px solid #eee;

You'll see they've reduced padding-left by 1px to allow for the addition of the new left border. Since this rule appears later in the source order, it overrides any previous or external declarations.

I'd argue this isn't exactly the most robust or elegant approach, but it illustrates the most basic example.

Error: No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlClient'

Add "EntityFramework.SqlServer.dll" into your bin folder. Problem will get resolved.

How to replace text in a column of a Pandas dataframe?

If you only need to replace characters in one specific column, somehow regex=True and in place=True all failed, I think this way will work:

data["column_name"] = data["column_name"].apply(lambda x: x.replace("characters_need_to_replace", "new_characters"))

lambda is more like a function that works like a for loop in this scenario. x here represents every one of the entries in the current column.

The only thing you need to do is to change the "column_name", "characters_need_to_replace" and "new_characters".

How to define the basic HTTP authentication using cURL correctly?

curl -u username:password http://
curl -u username http://

From the documentation page:

-u, --user <user:password>

Specify the user name and password to use for server authentication. Overrides -n, --netrc and --netrc-optional.

If you simply specify the user name, curl will prompt for a password.

The user name and passwords are split up on the first colon, which makes it impossible to use a colon in the user name with this option. The password can, still.

When using Kerberos V5 with a Windows based server you should include the Windows domain name in the user name, in order for the server to succesfully obtain a Kerberos Ticket. If you don't then the initial authentication handshake may fail.

When using NTLM, the user name can be specified simply as the user name, without the domain, if there is a single domain and forest in your setup for example.

To specify the domain name use either Down-Level Logon Name or UPN (User Principal Name) formats. For example, EXAMPLE\user and [email protected] respectively.

If you use a Windows SSPI-enabled curl binary and perform Kerberos V5, Negotiate, NTLM or Digest authentication then you can tell curl to select the user name and password from your environment by specifying a single colon with this option: "-u :".

If this option is used several times, the last one will be used.

Note that you do not need --basic flag as it is the default.

jQuery DatePicker with today as maxDate

In recent version, The following works fine:

        maxDate: new Date()

maxDate accepts a Date object as parameter.

The following found in documentation:

Multiple types supported:

  • Date: A date object containing the minimum date.

  • Number: A number of days from today. For example 2 represents two days from today and -1 represents yesterday.

  • String: A string in the format defined by the dateFormat option, or a relative date. Relative dates must contain value and period pairs; valid periods are "y" for years, "m" for months, "w" for weeks, and "d" for days. For example, "+1m +7d" represents one month and seven days from today.

Difference between Select Unique and Select Distinct

Unique is a keyword used in the Create Table() directive to denote that a field will contain unique data, usually used for natural keys, foreign keys etc.

For example:

Create Table Employee(   
    Emp_PKey Int Identity(1, 1) Constraint PK_Employee_Emp_PKey Primary Key,  
    Emp_SSN Numeric Not Null Unique,  
    Emp_FName varchar(16),   
    Emp_LName varchar(16) 

i.e. Someone's Social Security Number would likely be a unique field in your table, but not necessarily the primary key.

Distinct is used in the Select statement to notify the query that you only want the unique items returned when a field holds data that may not be unique.

Select Distinct Emp_LName
From Employee

You may have many employees with the same last name, but you only want each different last name.

Obviously if the field you are querying holds unique data, then the Distinct keyword becomes superfluous.

Turning multi-line string into single comma-separated

You can also do it with two sed calls:

$ cat file.txt 
something1:    +12.0   (some unnecessary trailing data (this must go))
something2:    +15.5   (some more unnecessary trailing data)
something4:    +9.0   (some other unnecessary data)
something1:    +13.5  (blah blah blah)
$ sed 's/^[^:]*: *\([+0-9.]\+\) .*/\1/' file.txt | sed -e :a -e '$!N; s/\n/,/; ta'

First sed call removes uninteresting data, and the second join all lines.

Verilog generate/genvar in an always block

for verilog just do

parameter ROWBITS = 4;
reg [ROWBITS-1:0] temp;
always @(posedge sysclk) begin
  temp <= {ROWBITS{1'b0}}; // fill with 0

How to place object files in separate subdirectory

None of these answers seemed simple enough - the crux of the problem is not having to rebuild:



# make will look in VPATH to see if the target needs to be rebuilt
test: moo
    touch $(OBJDIR)/$@

example use

touch moo
# creates out/test
make test
# doesn't update out/test
make test
# will now update test
touch moo
make test

Java 8 Streams FlatMap method example

Extract unique words sorted ASC from a list of phrases:

List<String> phrases = Arrays.asList(
        "sporadic perjury",
        "confounded skimming",
        "incumbent jailer",
        "confounded jailer");

List<String> uniqueWords = phrases
        .flatMap(phrase -> Stream.of(phrase.split("\\s+")))
System.out.println("Unique words: " + uniqueWords);

... and the output:

Unique words: [confounded, incumbent, jailer, perjury, skimming, sporadic]

Adding 1 hour to time variable

Worked for me..

$timestamp = strtotime('10:09') + 60*60;

$time = date('H:i', $timestamp);

echo $time;//11:09


strtotime('10:09') creates a numerical timestamp in seconds, something like 1510450372. Simply add or remove the amount of seconds you need and use date() to convert it back into a human readable format.

$timestamp = strtotime('10:09') + 60*60; // 10:09 + 1 hour
$timestamp = strtotime('10:09') + 60*60*2; // 10:09 + 2 hours
$timestamp = strtotime('10:09') - 60*60; // 10:09 - 1 hour

time() also creates a numerical timestamp but for right now. You can use it in the same way.

$timestamp = time() + 60*60; // now + 1 hour

How to simulate a click with JavaScript?

You could save yourself a bunch of space by using jQuery. You only need to use:


How to stop EditText from gaining focus at Activity startup in Android

It can be achieved by inheriting EditText and overriding onTouchEvent.

class NonFocusableEditText: EditText {

    constructor(context: Context): super(context)
    constructor(context: Context, attrs: AttributeSet?): super(context, attrs)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int): super(context, attrs, defStyleAttr)

    override fun onTouchEvent(event: MotionEvent?): Boolean {
        return if (isFocusable) super.onTouchEvent(event) else false

Then you can use it in the layouts like normal EditText:

        android:inputType="textNoSuggestions" />

How to check if a line is blank using regex

Full credit to bchr02 for this answer. However, I had to modify it a bit to catch the scenario for lines that have */ (end of comment) followed by an empty line. The regex was matching the non empty line with */.

New: (^(\r\n|\n|\r)$)|(^(\r\n|\n|\r))|^\s*$/gm

All I did is add ^ as second character to signify the start of line.

document.getElementById("remember").visibility = "hidden"; not working on a checkbox

There are two problems in your code:

  • The property is called visibility and not visiblity.
  • It is not a property of the element itself but of its .style property.

It's easy to fix. Simple replace this:


with this:


How to commit changes to a new branch

If I understand right, you've made a commit to changed_branch and you want to copy that commit to other_branch? Easy:

git checkout other_branch
git cherry-pick changed_branch

Java check to see if a variable has been initialized

Instance variables or fields, along with static variables, are assigned default values based on the variable type:

  • int: 0
  • char: \u0000 or 0
  • double: 0.0
  • boolean: false
  • reference: null

Just want to clarify that local variables (ie. declared in block, eg. method, for loop, while loop, try-catch, etc.) are not initialized to default values and must be explicitly initialized.

Usages of doThrow() doAnswer() doNothing() and doReturn() in mockito

doThrow : Basically used when you want to throw an exception when a method is being called within a mock object.

public void validateEntity(final Object object){}

doReturn : Used when you want to send back a return value when a method is executed.

public Socket getCosmosSocket() throws IOException {}

doAnswer: Sometimes you need to do some actions with the arguments that are passed to the method, for example, add some values, make some calculations or even modify them doAnswer gives you the Answer interface that being executed in the moment that method is called, this interface allows you to interact with the parameters via the InvocationOnMock argument. Also, the return value of answer method will be the return value of the mocked method.

public ReturnValueObject quickChange(Object1 object);
Mockito.doAnswer(new Answer<ReturnValueObject>() {

        public ReturnValueObject answer(final InvocationOnMock invocation) throws Throwable {

            final Object1 originalArgument = (invocation.getArguments())[0];
            final ReturnValueObject returnedValue = new ReturnValueObject();
            returnedValue.setCost(new Cost());

            return returnedValue ;

doNothing: Is the easiest of the list, basically it tells Mockito to do nothing when a method in a mock object is called. Sometimes used in void return methods or method that does not have side effects, or are not related to the unit testing you are doing.

public void updateRequestActionAndApproval(final List<Object1> cmItems);


Can I set a TTL for @Cacheable

Here is a full example of setting up Guava Cache in Spring. I used Guava over Ehcache because it's a bit lighter weight and the config seemed more straight forward to me.

Import Maven Dependencies

Add these dependencies to your maven pom file and run clean and packages. These files are the Guava dep and Spring helper methods for use in the CacheBuilder.


Configure the Cache

You need to create a CacheConfig file to configure the cache using Java config.

public class CacheConfig {

   public final static String CACHE_ONE = "cacheOne";
   public final static String CACHE_TWO = "cacheTwo";

   public Cache cacheOne() {
      return new GuavaCache(CACHE_ONE, CacheBuilder.newBuilder()
            .expireAfterWrite(60, TimeUnit.MINUTES)

   public Cache cacheTwo() {
      return new GuavaCache(CACHE_TWO, CacheBuilder.newBuilder()
            .expireAfterWrite(60, TimeUnit.SECONDS)

Annotate the method to be cached

Add the @Cacheable annotation and pass in the cache name.

public class CachedService extends WebServiceGatewaySupport implements CachedService {

    private RestTemplate restTemplate;

    public String getCached() {

        HttpHeaders headers = new HttpHeaders();

        HttpEntity<String> reqEntity = new HttpEntity<>("url", headers);

        ResponseEntity<String> response;

        String url = "url";
        response =
                HttpMethod.GET, reqEntity, String.class);

        return response.getBody();

You can see a more complete example here with annotated screenshots: Guava Cache in Spring

How may I align text to the left and text to the right in the same line?

If you're using Bootstrap try this:

<div class="row">
    <div class="col" style="text-align:left">left align</div>
    <div class="col" style="text-align:right">right align</div>

Mongoose delete array element in document and save

You can also do the update directly in MongoDB without having to load the document and modify it using code. Use the $pull or $pullAll operators to remove the item from the array :

Favorite.updateOne( {cn:}, { $pullAll: {uid: [req.params.deleteUid] } } )

(you can also use updateMany for multiple documents)

.htaccess redirect all pages to new domain

From the usability point of view it would be better, if you also send the path with the request (i.e., what you have at the moment) and let your new site deal with it:

You searched for "/products".

Unfortunately this page is gone. Would you like to visit "/new_products" instead?

(and better, still, doing this automatically.)

This is obviously a lot of coding and heuristics for a larger website, but in my opinion it would pay off in terms of user satisfaction (when your carefully saved bookmark of your dream product just leads you to the front page of, this is frustrating.)

How to calculate the SVG Path for an arc (of a circle)

I slightly modified the answer of opsb and made in support fill for the circle sector.


function polarToCartesian(centerX, centerY, radius, angleInDegrees) {
  var angleInRadians = (angleInDegrees-90) * Math.PI / 180.0;

  return {
    x: centerX + (radius * Math.cos(angleInRadians)),
    y: centerY + (radius * Math.sin(angleInRadians))

function describeArc(x, y, radius, startAngle, endAngle){

    var start = polarToCartesian(x, y, radius, endAngle);
    var end = polarToCartesian(x, y, radius, startAngle);

    var arcSweep = endAngle - startAngle <= 180 ? "0" : "1";

    var d = [
        "M", start.x, start.y, 
        "A", radius, radius, 0, arcSweep, 0, end.x, end.y,
        "L", x,y,
        "L", start.x, start.y
    ].join(" ");

    return d;       

document.getElementById("arc1").setAttribute("d", describeArc(200, 400, 100, 0, 220));


  <path id="arc1" fill="orange" stroke="#446688" stroke-width="0" />

Can I call jQuery's click() to follow an <a> link if I haven't bound an event handler to it with bind or click already?

JavaScript/jQuery doesn't support the default behavior of links "clicked" programmatically.

Instead, you can create a form and submit it. This way you don't have to use window.location or, which are often blocked as unwanted popups by browsers.

This script has two different methods: one that tries to open three new tabs/windows (it opens only one in Internet Explorer and Chrome, more information is below) and one that fires a custom event on a link click.

Here is how:


    <script src="jquery-1.9.1.min.js" type="text/javascript"></script>
    <script src="script.js" type="text/javascript"></script>

    <button id="testbtn">Test</button><br><br>

    <a href="">Google</a><br>
    <a href="">Wikipedia</a><br>
    <a href="">Stack Overflow</a>


jQuery (file script.js)

    // Try to open all three links by pressing the button
    // - Firefox opens all three links
    // - Chrome only opens one of them without a popup warning
    // - Internet Explorer only opens one of them WITH a popup warning
    $("#testbtn").on("click", function()
            var form = $("<form></form>");
                id     : "formform",
                action : $(this).attr("href"),
                method : "GET",
                // Open in new window/tab
                target : "_blank"


    // Or click the link and fire a custom event
    // (open your own window without following 
    // the link itself)
    $("a").on("click", function()
        var form = $("<form></form>");
            id     : "formform",
            // The location given in the link itself
            action : $(this).attr("href"),
            method : "GET",
            // Open in new window/tab
            target : "_blank"


        // Prevent the link from opening normally
        return false;

For each link element, it:

  1. Creates a form
  2. Gives it attributes
  3. Appends it to the DOM so it can be submitted
  4. Submits it
  5. Removes the form from the DOM, removing all traces *Insert evil laugh*

Now you have a new tab/window loading "" (or any URL you want, just replace it). Unfortunately when you try to open more than one window this way, you get an Popup blocked messagebar when trying to open the second one (the first one is still opened).

More information on how I got to this method is found here:

What's the foolproof way to tell which version(s) of .NET are installed on a production Windows Server?

Also, see the Stack Overflow question How to detect what .NET Framework versions and service packs are installed? which also mentions:

There is an official Microsoft answer to this question at the knowledge base article [How to determine which versions and service pack levels of the Microsoft .NET Framework are installed][2]

Article ID: 318785 - Last Review: November 7, 2008 - Revision: 20.1 How to determine which versions of the .NET Framework are installed and whether service packs have been applied.

Unfortunately, it doesn't appear to work, because the mscorlib.dll version in the 2.0 directory has a 2.0 version, and there is no mscorlib.dll version in either the 3.0 or 3.5 directories even though 3.5 SP1 is installed ... Why would the official Microsoft answer be so misinformed?

Multi-line strings in PHP

PHP has Heredoc and Nowdoc strings, which are the best way to handle multiline strings in PHP.

$str = <<<EOD
Example of string
spanning multiple lines
using heredoc syntax.
$var is replaced automatically.

A Nowdoc is like a Heredoc, but it doesn't replace variables.

$str = <<<'EOD'
Example of string
spanning multiple lines
using nowdoc syntax.
$var is NOT replaced in a nowdoc.

Beware that the end token EOD must not be indented at all, or PHP won't acknowledge it. Also, you don't have to use "EOD"; it can be any string you want.

Fastest way to remove non-numeric characters from a VARCHAR in SQL Server

I would try Scott's CLR function first but add a WHERE clause to reduce the number of records updated.

UPDATE table SET phoneNumber = dbo.StripNonNumeric(phoneNumber) 
WHERE phonenumber like '%[^0-9]%'

If you know that the great majority of your records have non-numeric characters it might not help though.

Connecting to TCP Socket from browser using javascript

ws2s project is aimed at bring socket to browser-side js. It is a websocket server which transform websocket to socket.

ws2s schematic diagram

enter image description here

code sample:

var socket = new WS2S("wss://").newSocket()

socket.onReady = () => {
  socket.connect("", 80)
  socket.send("GET / HTTP/1.1\r\nHost:\r\nConnection: close\r\n\r\n")

socket.onRecv = (data) => {
  console.log('onRecv', data)

Regex date format validation on Java

Construct a SimpleDateFormat with the mask, and then call: SimpleDateFormat.parse(String s, ParsePosition p)

Errno 10061 : No connection could be made because the target machine actively refused it ( client - server )

The first: Please make sure your port '12345' is opening and then when you using a different network. You have to use the IP address in LAN. Don't use the 'localhost' or ''. The solution here is: In server

host = '' #Ip address in LAN network

In client

host = '' # external IP Address

Hope it works for you

Youtube - downloading a playlist - youtube-dl

Download YouTube playlist videos in separate directory indexed by video order in a playlist

$ youtube-dl -o '%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s'

Download all playlists of YouTube channel/user keeping each playlist in separate directory:

$ youtube-dl -o '%(uploader)s/%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s'

Video Selection:

youtube-dl is a command-line program to download videos from and a few more sites. It requires the Python interpreter, version 2.6, 2.7, or 3.2+, and it is not platform specific. It should work on your Unix box, on Windows or on macOS. It is released to the public domain, which means you can modify it, redistribute it or use it however you like.

$ youtube-dl [OPTIONS] URL [URL...]
--playlist-start NUMBER          Playlist video to start at (default is 1)

--playlist-end NUMBER            Playlist video to end at (default is last)

--playlist-items ITEM_SPEC       Playlist video items to download. Specify
                                 indices of the videos in the playlist
                                 separated by commas like: "--playlist-items
                                 1,2,5,8" if you want to download videos
                                 indexed 1, 2, 5, 8 in the playlist. You can
                                 specify range: "--playlist-items
                                 1-3,7,10-13", it will download the videos
                                 at index 1, 2, 3, 7, 10, 11, 12 and 13.

Jquery select this + class

What you are looking for is this:

$(".subclass", this).css("visibility","visible");

Add the this after the class $(".subclass", this)

Is there any option to limit mongodb memory usage?

this worked for me on an AWS instance, to at least clear the cached memory mongo was using. after this you can see how your settings have had effect.

ubuntu@hongse:~$ free -m
             total       used       free     shared    buffers     cached
Mem:          3952       3667        284          0        617        514
-/+ buffers/cache:       2535       1416
Swap:            0          0          0
ubuntu@hongse:~$ sudo su
root@hongse:/home/ubuntu# sync; echo 3 > /proc/sys/vm/drop_caches
root@hongse:/home/ubuntu# free -m
             total       used       free     shared    buffers     cached
Mem:          3952       2269       1682          0          1         42
-/+ buffers/cache:       2225       1726
Swap:            0          0          0

CSS Outside Border

Try the outline property W3Schools - CSS Outline

Outline will not interfere with widths and lenghts of the elements/divs!

Please click the link I provided at the bottom to see working demos of the the different ways you can make borders, and inner/inline borders, even ones that do not disrupt the dimensions of the element! No need to add extra divs every time, as mentioned in another answer!

You can also combine borders with outlines, and if you like, box-shadows (also shown via link)

   <style type="text/css" ref="stylesheet">
      div {
        outline:1px solid black;

Usually by default, 'border:' puts the border on the outside of the width, measurement, adding to the overall dimensions, unless you use the 'inset' value:

div {border: inset solid 1px black};

But 'outline:' is an extra border outside of the border, and of course still adds extra width/length to the element.

Hope this helps

PS: I also was inspired to make this for you : Using borders, outlines, and box-shadows

Warning: mysqli_select_db() expects exactly 2 parameters, 1 given in C:\

mysqli_select_db() should have 2 parameters, the connection link and the database name -

mysqli_select_db($con, 'phpcadet') or die(mysqli_error($con));

Using mysqli_error in the die statement will tell you exactly what is wrong as opposed to a generic error message.

Spring MVC 4: "application/json" Content Type is not being set correctly

I had the dependencies as specified @Greg post. I still faced the issue and could be able to resolve it by adding following additional jackson dependency:


html - table row like a link

This saves you having to duplicate the link in the tr - just fish it out of the first a.

$(".link-first-found").click(function() {
 var href;
href = $(this).find("a").attr("href");
if (href !== "") {
return document.location = href;

How can I change UIButton title color?

If you are using Swift, this will do the same:

buttonName.setTitleColor(UIColor.blackColor(), forState: .Normal)

Hope that helps!

How to generate a Makefile with source in sub-directories using just one makefile

This will do it without painful manipulation or multiple command sequences:

build/%.o: src/%.cpp
src/%.o: src/%.cpp
    $(CC) -c $< -o $@

build/test.exe: build/widgets/apple.o build/widgets/knob.o build/tests/blend.o src/ui/flash.o
    $(LD) $^ -o $@

JasperE has explained why "%.o: %.cpp" won't work; this version has one pattern rule (%.o:) with commands and no prereqs, and two pattern rules (build/%.o: and src/%.o:) with prereqs and no commands. (Note that I put in the src/%.o rule to deal with src/ui/flash.o, assuming that wasn't a typo for build/ui/flash.o, so if you don't need it you can leave it out.)

build/test.exe needs build/widgets/apple.o,
build/widgets/apple.o looks like build/%.o, so it needs src/%.cpp (in this case src/widgets/apple.cpp),
build/widgets/apple.o also looks like %.o, so it executes the CC command and uses the prereqs it just found (namely src/widgets/apple.cpp) to build the target (build/widgets/apple.o)

Manually install Gradle and use it in Android Studio

Android Studio will automatically use the Gradle wrapper and pull the correct version of Gradle rather than use a locally installed version. If you wish to use a new version of Gradle, you can change the version used by studio. Beneath your Android Studio's project tree, open the file gradle/wrapper/ Change this entry:


UL list style not applying

This problem was caused by the li display attribute being set to block in a parent class. Overriding with list-item solved the problem.

java.lang.UnsupportedClassVersionError: Bad version number in .class file?

i solved this problem by changing jre required for server (in my case is tomcat). From Server tab in eclipse, double click on the server (in order to open page for server configuration), click on Runtime environment, then change JRE required

Minimum and maximum date

From the spec, §

A Date object contains a Number indicating a particular instant in time to within a millisecond. Such a Number is called a time value. A time value may also be NaN, indicating that the Date object does not represent a specific instant of time.

Time is measured in ECMAScript in milliseconds since 01 January, 1970 UTC. In time values leap seconds are ignored. It is assumed that there are exactly 86,400,000 milliseconds per day. ECMAScript Number values can represent all integers from –9,007,199,254,740,992 to 9,007,199,254,740,992; this range suffices to measure times to millisecond precision for any instant that is within approximately 285,616 years, either forward or backward, from 01 January, 1970 UTC.

The actual range of times supported by ECMAScript Date objects is slightly smaller: exactly –100,000,000 days to 100,000,000 days measured relative to midnight at the beginning of 01 January, 1970 UTC. This gives a range of 8,640,000,000,000,000 milliseconds to either side of 01 January, 1970 UTC.

The exact moment of midnight at the beginning of 01 January, 1970 UTC is represented by the value +0.

The third paragraph being the most relevant. Based on that paragraph, we can get the precise earliest date per spec from new Date(-8640000000000000), which is Tuesday, April 20th, 271,821 BCE (BCE = Before Common Era, e.g., the year -271,821).

iterating through json object javascript

Here is my recursive approach:

function visit(object) {
    if (isIterable(object)) {
        forEachIn(object, function (accessor, child) {
    else {
        var value = object;

function forEachIn(iterable, functionRef) {
    for (var accessor in iterable) {
        functionRef(accessor, iterable[accessor]);

function isIterable(element) {
    return isArray(element) || isObject(element);

function isArray(element) {
    return element.constructor == Array;

function isObject(element) {
    return element.constructor == Object;

Go install fails with error: no install location for directory xxx outside GOPATH

You'll want to have 3 directories inside your chosen GOPATH directory.


Then you'll run go install from inside either someProgram (which puts an executable in bin) or someLibrary (which puts a library in pkg).

Fastest way to add an Item to an Array

It depends on how often you insert or read. You can increase the array by more than one if needed.

numberOfItems = ??

' ...

If numberOfItems+1 >= arr.Length Then
    Array.Resize(arr, arr.Length + 10)
End If

arr(numberOfItems) = newItem
numberOfItems += 1

Also for A, you only need to get the array if needed.

Dim list As List(Of Integer)(arr) ' Do this only once, keep a reference to the list
                                  ' If you create a new List everything you add an item then this will never be fast


arrayWasModified = True

' ...

Function GetArray()

    If arrayWasModified Then
        arr = list.ToArray()
    End If

    Return Arr
End Function

If you have the time, I suggest you convert it all to List and remove arrays.

* My code might not compile

How can I align all elements to the left in JPanel?

The easiest way I've found to place objects on the left is using FlowLayout.

JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));

adding a component normally to this panel will place it on the left

What's the difference between MyISAM and InnoDB?


  1. MYISAM supports Table-level Locking
  2. MyISAM designed for need of speed
  3. MyISAM does not support foreign keys hence we call MySQL with MYISAM is DBMS
  4. MyISAM stores its tables, data and indexes in diskspace using separate three different files. (tablename.FRM, tablename.MYD, tablename.MYI)
  5. MYISAM not supports transaction. You cannot commit and rollback with MYISAM. Once you issue a command it’s done.
  6. MYISAM supports fulltext search
  7. You can use MyISAM, if the table is more static with lots of select and less update and delete.


  1. InnoDB supports Row-level Locking
  2. InnoDB designed for maximum performance when processing high volume of data
  3. InnoDB support foreign keys hence we call MySQL with InnoDB is RDBMS
  4. InnoDB stores its tables and indexes in a tablespace
  5. InnoDB supports transaction. You can commit and rollback with InnoDB

Python convert csv to xlsx

There is a simple way

import os
import csv
import sys

from openpyxl import Workbook


if __name__ == '__main__':
    workbook = Workbook()
    worksheet =
    with open('input.csv', 'r') as f:
        reader = csv.reader(f)
        for r, row in enumerate(reader):
            for c, col in enumerate(row):
                for idx, val in enumerate(col.split(',')):
                    cell = worksheet.cell(row=r+1, column=c+1)
                    cell.value = val'output.xlsx')

Get child node index

Adding a (prefixed for safety) element.getParentIndex():

Element.prototype.PREFIXgetParentIndex = function() {
  return, this);

javascript - replace dash (hyphen) with a space

This fixes it:

let str = "This-is-a-news-item-";
str = str.replace(/-/g, ' ');

There were two problems with your code:

  1. First, String.replace() doesn’t change the string itself, it returns a changed string.
  2. Second, if you pass a string to the replace function, it will only replace the first instance it encounters. That’s why I passed a regular expression with the g flag, for 'global', so that all instances will be replaced.

What is the best IDE to develop Android apps in?

You can also develop rich UI filled Android applications using Adobe AIR. If you plan to go that route then Flex Builder Burrito is the best IDE. Take a look at this post as to how easy it is to build an AIR4Android app

Xcode: failed to get the task for process

Having the developer code signing id is correct for sure, but also make sure you device is added to the Member Center via organizer, or through the developer portal.

A few days ago I reset my device list, and today I was suddenly getting this for an iPod I debug with all the time. About 15 mins later I realized the problem.

PHP foreach change original array values

Use foreach($fields as &$field){ - so you will work with the original array.

Here is more about passing by reference.

MongoDB Data directory /data/db not found

MongoDB needs data directory to store data. Default path is /data/db

When you start MongoDB engine, it searches this directory which is missing in your case. Solution is create this directory and assign rwx permission to user.

If you want to change the path of your data directory then you should specify it while starting mongod server like,

mongod --dbpath /data/<path> --port <port no> 

This should help you start your mongod server with custom path and port.

Import Script from a Parent Directory

From the docs:

from .. import scriptA

You can do this in packages, but not in scripts you run directly. From the link above:

Note that both explicit and implicit relative imports are based on the name of the current module. Since the name of the main module is always "__main__", modules intended for use as the main module of a Python application should always use absolute imports.

If you create a script that imports A.B.B, you won't receive the ValueError.

Get IP address of an interface on Linux

If you're looking for an address (IPv4) of the specific interface say wlan0 then try this code which uses getifaddrs():

#include <arpa/inet.h>
#include <sys/socket.h>
#include <netdb.h>
#include <ifaddrs.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char *argv[])
    struct ifaddrs *ifaddr, *ifa;
    int family, s;
    char host[NI_MAXHOST];

    if (getifaddrs(&ifaddr) == -1) 

    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) 
        if (ifa->ifa_addr == NULL)

        s=getnameinfo(ifa->ifa_addr,sizeof(struct sockaddr_in),host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);

            if (s != 0)
                printf("getnameinfo() failed: %s\n", gai_strerror(s));
            printf("\tInterface : <%s>\n",ifa->ifa_name );
            printf("\t  Address : <%s>\n", host); 


You can replace wlan0 with eth0 for ethernet and lo for local loopback.

The structure and detailed explanations of the data structures used could be found here.

To know more about linked list in C this page will be a good starting point.

Spring Boot application can't resolve the org.springframework.boot package

I have encountered the same problem while my first Spring boot application.

In tutorial i could see following dependency to start sample application

  • Spring Boot 1.4.2.RELEASE
  • Maven 3
  • java 8

I have done the same, my Spring STS is recognizing all class but when i am annotating my main class with @SpringBootApplication it's not recognizing this class whereas i could see jar was available in the class path.

I have following to resolve issues

  • Replaced my Spring Boot 1.4.2.RELEASE to 1.5.3.RELEASE
  • Right click on project and -> Maven-> Download Resources
  • right click on project -> Maven-> Update project

After that it worked.


How do I rename a MySQL schema?

If you're on the Model Overview page you get a tab with the schema. If you rightclick on that tab you get an option to "edit schema". From there you can rename the schema by adding a new name, then click outside the field. This goes for MySQL Workbench 5.2.30 CE

Edit: On the model overview it's under Physical Schemata


enter image description here

How can I use Timer (formerly NSTimer) in Swift?

You will need to use Timer instead of NSTimer in Swift 3.

Here is an example:

Timer.scheduledTimer(timeInterval: 1, 
    target: self, 
    selector: #selector(YourController.update), 
    userInfo: nil, 
    repeats: true)

// @objc selector expected for Timer
@objc func update() {
    // do what should happen when timer triggers an event

Is #pragma once a safe include guard?

I wish #pragma once (or something like it) had been in the standard. Include guards aren't a real big deal (but they do seem to be a little difficult to explain to people learning the language), but it seems like a minor annoyance that could have been avoided.

In fact, since 99.98% of the time, the #pragma once behavior is the desired behavior, it would have been nice if preventing multiple inclusion of a header was automatically handled by the compiler, with a #pragma or something to allow double including.

But we have what we have (except that you might not have #pragma once).

An error occurred while signing: SignTool.exe not found

Windows 10 users can find signtool.exe in C:\Program Files (x86)\Windows Kits\10\bin\10.0.18362.0\x64 folder (10.0.18362.0 in my case, or other version).

But first, make sure you've installed Windows 10 SDK

Then, check Windows SDK Signing Tools for Desktop Apps is installed by going to Control Panel > Programs > Programs and Features, choose Windows Software Development Kit - Windows 10.0.18362.1 (in my case, you version may be different), right-click, choose Change, choose options Change then click Next.

How to embed a Facebook page's feed into my website

Correct me if I am wrong, but it seems that Facebook deprecated the Activity Feed plugin. Additionally there does not seem to be any substitute plugin for activity anymore.

Here is the link:

Difference between frontend, backend, and middleware in web development

Here is one breakdown:

Front-end tier -> User Interface layer usually consisting of a mix of HTML, Javascript, CSS, Flash, and various server-side code like ASP.Net, classic ASP, PHP, etc. Think of this as being closest to the user in terms of code.

Middleware, middle-tier -> One tier back, generally referred to as the "plumbing" part of a system. Java and C# are common languages for writing this part that could be viewed as the glue between the UI and the data and can be webservices or WCF components or other SOA components possibly.

Back-end tier -> Databases and other data stores are generally at this level. Oracle, MS-SQL, MySQL, SAP, and various off-the-shelf pieces of software come to mind for this piece of software that is the final processing of the data.

Overlap can exist between any of these as you could have everything poured into one layer like an ASP.Net website that uses the built-in AJAX functionality that generates Javascript while the code behind may contain database commands making the code behind contain both middle and back-end tiers. Alternatively, one could use VBScript to act as all the layers using ADO objects and merging all three tiers into one.

Similarly, taking middleware and either front or back-end can be combined in some cases.

Bottlenecks generally have a few different levels to them:

1) Database or back-end processing -> This can vary from payroll or sales or other tasks where the throughput to the database is bogging things down.

2) Middleware bottlenecks -> This would be where some web service may be hitting capacity but the front and back ends have bandwidth to handle more traffic. Alternatively, there may be some server that is part of a system that isn't quite the UI part or the raw data that can be a bottleneck using something like Biztalk or MSMQ.

3) Front-end bottlenecks -> This could client or server-side issues. For example, if you took a low-end PC and had it load a web page that consisted of a lot of data being downloaded, the client could be where the bottleneck is. Similarly, the server could be queuing up requests if it is getting hammered with requests like what or other high-traffic websites may get at times.

Some of this is subject to interpretation, so it isn't perfect by any means and YMMV.

EDIT: Something to consider is that some systems can have multiple front-ends or back-ends. For example, a content management system will likely have a way for site visitors to view the content that is a front-end but what about how content editors are able to change the data on the site? The ability to pull up this data could be seen as front-end since it is a UI component or it could be seen as a back-end since it is used by internal users rather than the general public viewing the site. Thus, there is something to be said for context here.

LINQ equivalent of foreach for IEnumerable<T>

According to PLINQ (available since .Net 4.0), you can do an


to do a parallel foreach loop on an IEnumerable.

Installing SQL Server 2012 - Error: Prior Visual Studio 2010 instances requiring update

there are two way:

First :

Inside your CD of SQL Server 2012

you can go to this path \redist\VisualStudioShell.

And you most install this file VS10sp1-KB983509.msp.

After several minutes your problem fix.

Restart your computer and then fire SetUp of SQL Server 2012.

See this picture.

enter image description here

Secound :

But if you want download online Service Pack 1 view This Link

And press download.

After download run this exe file and let it download and fix your VS2010 to VS2010 SP1.

And then restart your windows.

After this operation you can install SQL Server 2012

enter image description here

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

addToCart(docId: string, prodId: string): Promise<void> {
    return this.baseAngularFirestore.collection('carts').doc(docId).update({
            productId: prodId,
            qty: 1

How do I parse command line arguments in Java?

Take a look at the Commons CLI project, lots of good stuff in there.

Mongoose's find method with $or condition does not work properly

I solved it through googling:

var ObjectId = require('mongoose').Types.ObjectId;
var objId = new ObjectId( (param.length < 12) ? "123456789012" : param );
// You should make string 'param' as ObjectId type. To avoid exception, 
// the 'param' must consist of more than 12 characters.

User.find( { $or:[ {'_id':objId}, {'name':param}, {'nickname':param} ]}, 
    if(!err) res.send(docs);

Microsoft.WebApplication.targets was not found, on the build server. What's your solution?

The latest Windows SDK, as mentioned above, in addition to the "Microsoft Visual Studio 2010 Shell (Integrated) Redistributable Package" for Microsoft.WebApplication.targets and "Microsoft Visual Studio Team System 2008 Database Edition GDR R2" for Microsoft.Data.Schema.SqlTasks.targets should alleviate the need to install Visual Studio 2010. However, installing VS 2010 maybe actually be less overall to download and less work in the end.

How to remove/ignore :hover css style on touch devices

I have encountered the same problem (in my case with Samsung mobile browsers) and therefore I stumbled upon this question.

Thanks to Calsal's answer I found something that I believe will exclude virtually all desktop browsers because it seems to be recognized by the mobile browsers I tried (see screenshot from a compiled table: CSS pointer feature detection table ).

MDN web docs state that

The pointer CSS @media feature can be used to apply styles based on whether the user's primary input mechanism is a pointing device, and if so, how accurate it is


What I discovered is that pointer: coarse is something that is unknown to all desktop browsers in the attached table but known to all mobile browsers in the same table. This seems to be most effective choice because all other pointer keyword values give inconsistent results.

Hence you could construct a media query like Calsal described but slightly modified. It makes use of a reversed logic to rule out all touch devices.

Sass mixin:

@mixin hover-supported {    
     * coarse: The primary input mechanism includes a pointing device of limited accuracy.
    @media not all and (pointer: coarse) {
        &:hover {

a {

    @include hover-supported() {

Compiled CSS:

a {
  color: green;
  border-color: blue;
@media not all and (pointer: coarse) {
  a:hover {
    color: blue;
    border-color: green;

It is also described in this gist I created after researching the problem. Codepen for empirical research.

UPDATE: As of writing this update, 2018-08-23, and pointed out by @DmitriPavlutin this technique no longer seems to work with Firefox desktop.

How can I listen for keypress event on the whole page?

Just to add to this in 2019 w Angular 8,

instead of keypress I had to use keydown

@HostListener('document:keypress', ['$event'])


@HostListener('document:keydown', ['$event'])

Working Stacklitz

Plot a legend outside of the plotting area in base graphics?

Sorry for resurrecting an old thread, but I was with the same problem today. The simplest way that I have found is the following:

# Expand right side of clipping rect to make room for the legend
par(xpd=T, mar=par()$mar+c(0,0,0,6))

# Plot graph normally
plot(1:3, rnorm(3), pch = 1, lty = 1, type = "o", ylim=c(-2,2))
lines(1:3, rnorm(3), pch = 2, lty = 2, type="o")

# Plot legend where you want
legend(3.2,1,c("group A", "group B"), pch = c(1,2), lty = c(1,2))

# Restore default clipping rect
par(mar=c(5, 4, 4, 2) + 0.1)

Found here:

Removing Java 8 JDK from Mac

Use /usr/libexec/java_home ; I found these alias and function to be pretty useful in my ~/.profile:

alias java_ls='/usr/libexec/java_home -V 2>&1 | cut -s -d , -f 1 | cut -c 5-'
function java_use() {
    export JAVA_HOME=$(/usr/libexec/java_home -v $1)
    java -version

Font Awesome icon inside text input element



<div class="inp1">          
<a href="#" class=""><i class="fa fa-search"></i></a>

Opening a new tab to read a PDF file

As everyone else has pointed out, this can work:

<a href="newsletter_01.pdf" target="_blank">Read more</a> 

But what nobody has pointed out is that it's not guaranteed to work.

There is no way to force a user's browser to open a PDF file in a new tab. Depending on the user's browser settings, even with target="_blank" the browser may react the following ways:

  1. Ask for action
  2. Open it in Adobe Acrobat
  3. Simply download the file directly to their computer

Take a look at Firefox's settings, for example:

enter image description here

Chrome has a similar setting:

enter image description here

If the user has chosen to "Save File" in their browsers settings when encountering a PDF, there is no way you can override it.

What is the difference between signed and unsigned variables?

Unsigned variables can only be positive numbers, because they lack the ability to indicate that they are negative.

This ability is called the 'sign' or 'signing bit'.

A side effect is that without a signing bit, they have one more bit that can be used to represent the number, doubling the maximum number it can represent.

How to start automatic download of a file in Internet Explorer?

Nice jquery solution:


You can even set different file name for download inside <a> tag:

Your download should start shortly. If not - you can use
<a href="/" download="" class="download auto-start">direct link</a>.

CSS hide scroll bar if not needed

Set overflow-y property to auto, or remove the property altogether if it is not inherited.

How to 'update' or 'overwrite' a python list

I would prefer it without enumerate and instead use "range" like this:

for item in range(0, len(alist)):
   if 123 in alist[item]:
      alist[item] = 2014

For those who are new to python it might be more readable and a little smarter to recap.

Regards P.

Uninitialized constant ActiveSupport::Dependencies::Mutex (NameError)

I have faced this problem in many occassions when I try to start an old rails 2.3.5 project after having worked with rails 3>. In my case to solve the problem, I must do a rubygems update to version 1.4.2, this is:

sudo gem update --system 1.4.2

Check if an object exists

You can also use get_object_or_404(), it will raise a Http404 if the object wasn't found:

user_pass = log_in(request.POST) #form class
if user_pass.is_valid():
    cleaned_info = user_pass.cleaned_data
    user_object = get_object_or_404(User, email=cleaned_info['username'])
    # User object found, you are good to go!

Flutter Countdown Timer

doesnt directly answer your question. But helpful for those who want to start something after some time.

Future.delayed(Duration(seconds: 1), () {
            print('yo hey');

How to get the current date without the time?

string now = Convert.ToString(DateTime.Now.ToShortDateString());

How to handle command-line arguments in PowerShell

You are reinventing the wheel. Normal PowerShell scripts have parameters starting with -, like script.ps1 -server http://devserver

Then you handle them in param section in the beginning of the file.

You can also assign default values to your params, read them from console if not available or stop script execution:

 param (
    [string]$server = "http://defaultserver",
    [string]$password = $( Read-Host "Input password, please" )

Inside the script you can simply

write-output $server

since all parameters become variables available in script scope.

In this example, the $server gets a default value if the script is called without it, script stops if you omit the -username parameter and asks for terminal input if -password is omitted.

Update: You might also want to pass a "flag" (a boolean true/false parameter) to a PowerShell script. For instance, your script may accept a "force" where the script runs in a more careful mode when force is not used.

The keyword for that is [switch] parameter type:

 param (
    [string]$server = "http://defaultserver",
    [string]$password = $( Read-Host "Input password, please" ),
    [switch]$force = $false

Inside the script then you would work with it like this:

if ($force) {
  //deletes a file or does something "bad"

Now, when calling the script you'd set the switch/flag parameter like this:

.\yourscript.ps1 -server "http://otherserver" -force

If you explicitly want to state that the flag is not set, there is a special syntax for that

.\yourscript.ps1 -server "http://otherserver" -force:$false

Links to relevant Microsoft documentation (for PowerShell 5.0; tho versions 3.0 and 4.0 are also available at the links):

Giving graphs a subtitle in matplotlib

What I do is use the title() function for the subtitle and the suptitle() for the main title (they can take different fontsize arguments). Hope that helps!

Array of arrays (Python/NumPy)



tolist method mentioned above will return the nested Python list

SQL QUERY replace NULL value in a row with a value from the previous known value

If you're looking for a solution for Redshift, this will work with the frame clause:

SELECT date, 
       last_value(columnName ignore nulls) 
                   over (order by date
                         rows between unbounded preceding and current row) as columnName 
 from tbl

If hasClass then addClass to parent

If anyone is using WordPress, you can use something like:

if (jQuery('.dropdown-menu li').hasClass('active')) {

jQuery find parent form

As of HTML5 browsers one can use inputElement.form - the value of the attribute must be an id of a <form> element in the same document. More info on MDN.

Convert String value format of YYYYMMDDHHMMSS to C# DateTime

class Program
    static void Main(string[] args)

        int transactionDate = 20201010;
        int? transactionTime = 210000;

        var agreementDate = DateTime.Today;
        var previousDate = agreementDate.AddDays(-1);

        var agreementHour = 22;
        var agreementMinute = 0;
        var agreementSecond = 0;

        var startDate = new DateTime(previousDate.Year, previousDate.Month, previousDate.Day, agreementHour, agreementMinute, agreementSecond);
        var endDate = new DateTime(agreementDate.Year, agreementDate.Month, agreementDate.Day, agreementHour, agreementMinute, agreementSecond);

        DateTime selectedDate = Convert.ToDateTime(transactionDate.ToString().Substring(6, 2) + "/" + transactionDate.ToString().Substring(4, 2) + "/" + transactionDate.ToString().Substring(0, 4) + " " + string.Format("{0:00:00:00}", transactionTime));

        Console.WriteLine("Selected Date : " + selectedDate.ToString());
        Console.WriteLine("Start Date : " + startDate.ToString());
        Console.WriteLine("End Date : " + endDate.ToString());

        if (selectedDate > startDate && selectedDate <= endDate)
            Console.WriteLine("Between two dates..");
        else if (selectedDate <= startDate)
            Console.WriteLine("Less than or equal to the start date!");
        else if (selectedDate > endDate)
            Console.WriteLine("Greater than end date!");
            Console.WriteLine("Out of date ranges!");

JDK was not found on the computer for NetBeans 6.5

I have same problem, and solve by this way:

  1. Open CMD
  2. Go to file netbeans.exe
  3. Press Shift Key + Right Click and copy as path Copy as path
  4. Paste on CMD look like C:\Users\unnamed>"C:\Users\unnamed\Downloads\Programs\netbeans-8.2-windows.exe"
  5. Write --javahome do same point 2 on JDK folder
  6. Write on cmd look like C:\Users\unnamed>"C:\Users\unnamed\Downloads\Programs\netbeans-8.2-windows.exe" --javahome "C:\Program Files\Java\jdk-9.0.4"

  7. Enter. Enjoy it.

How do I change the root directory of an Apache server?

Please note, that this only applies for Ubuntu 14.04 LTS and newer releases.

In my Ubuntu 14.04 LTS, the document root was set to /var/www/html. It was configured in the following file:


So just do a

sudo nano /etc/apache2/sites-available/000-default.conf

and change the following line to what you want:

DocumentRoot /var/www/html

Also do a

sudo nano /etc/apache2/apache2.conf

and find this

<Directory /var/www/html/>
Options Indexes FollowSymLinks
AllowOverride None
Require all granted

and change /var/www/html to your preferred directory

and save it.

After you saved your changes, just restart the apache2 webserver and you'll be done :)

sudo service apache2 restart

If you prefer a graphical text editor, you can just replace the sudo nano by a gksu gedit.