Programs & Examples On #Numericstepper

Remote Procedure call failed with sql server 2008 R2

I can't comment yet, but make sure you made all the checks in this quide: How to enable remote connections in SQL Server 2008? It should work fine if all steps are made.

What is the backslash character (\\)?

\ is used for escape sequences in programming languages.

\n prints a newline
\\ prints a backslash
\" prints "
\t prints a tabulator
\b moves the cursor one back

DateTime "null" value

For normal DateTimes, if you don't initialize them at all then they will match DateTime.MinValue, because it is a value type rather than a reference type.

You can also use a nullable DateTime, like this:

DateTime? MyNullableDate;

Or the longer form:

Nullable<DateTime> MyNullableDate;

And, finally, there's a built in way to reference the default of any type. This returns null for reference types, but for our DateTime example it will return the same as DateTime.MinValue:

default(DateTime)

or, in more recent versions of C#,

default

remove kernel on jupyter notebook

If you are doing this for virtualenv, the kernels in inactive environments might not be shown with jupyter kernelspec list, as suggested above. You can delete it from directory:

~/.local/share/jupyter/kernels/

Create a global variable in TypeScript

Okay, so this is probably even uglier that what you did, but anyway...

but I do the same so...

What you can do to do it in pure TypeScript, is to use the eval function like so :

declare var something: string;
eval("something = 'testing';")

And later you'll be able to do

if (something === 'testing')

This is nothing more than a hack to force executing the instruction without TypeScript refusing to compile, and we declare var for TypeScript to compile the rest of the code.

How to group pandas DataFrame entries by date in a non-unique column

ecatmur's solution will work fine. This will be better performance on large datasets, though:

data.groupby(data['date'].map(lambda x: x.year))

Type.GetType("namespace.a.b.ClassName") returns null

Try this method.

public static Type GetType(string typeName)
{
    var type = Type.GetType(typeName);
    if (type != null) return type;
    foreach (var a in AppDomain.CurrentDomain.GetAssemblies())
    {
        type = a.GetType(typeName);
        if (type != null)
            return type;
    }
    return null;
}

Most efficient solution for reading CLOB to String, and String to CLOB in Java?

I can not use the "int length" constructor for StringBuilder since the length of my CLOB is longer than a int and needs a long value.

If the CLOB length is greater than fits in an int, the CLOB data won't fit in a String either. You'll have to use a streaming approach to deal with this much XML data.

If the actual length of the CLOB is smaller than Integer.MAX_VALUE, just force the long to int by putting (int) in front of it.

How to close a Java Swing application from the code

If I understand you correctly you want to close the application even if the user did not click on the close button. You will need to register WindowEvents maybe with addWindowListener() or enableEvents() whichever suits your needs better.

You can then invoke the event with a call to processWindowEvent(). Here is a sample code that will create a JFrame, wait 5 seconds and close the JFrame without user interaction.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ClosingFrame extends JFrame implements WindowListener{

public ClosingFrame(){
    super("A Frame");
    setSize(400, 400);
            //in case the user closes the window
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            setVisible(true);
            //enables Window Events on this Component
            this.addWindowListener(this);

            //start a timer
    Thread t = new Timer();
            t.start();
    }

public void windowOpened(WindowEvent e){}
public void windowClosing(WindowEvent e){}

    //the event that we are interested in
public void windowClosed(WindowEvent e){
    System.exit(0);
}

public void windowIconified(WindowEvent e){}
public void windowDeiconified(WindowEvent e){}
public void windowActivated(WindowEvent e){}
public void windowDeactivated(WindowEvent e){}

    //a simple timer 
    class Timer extends Thread{
           int time = 10;
           public void run(){
     while(time-- > 0){
       System.out.println("Still Waiting:" + time);
               try{
                 sleep(500);                     
               }catch(InterruptedException e){}
             }
             System.out.println("About to close");
    //close the frame
            ClosingFrame.this.processWindowEvent(
                 new WindowEvent(
                       ClosingFrame.this, WindowEvent.WINDOW_CLOSED));
           }
    }

    //instantiate the Frame
public static void main(String args[]){
          new ClosingFrame();
    }

}

As you can see, the processWindowEvent() method causes the WindowClosed event to be fired where you have an oportunity to do some clean up code if you require before closing the application.

What is the difference between Numpy's array() and asarray() functions?

The difference can be demonstrated by this example:

  1. generate a matrix

    >>> A = numpy.matrix(numpy.ones((3,3)))
    >>> A
    matrix([[ 1.,  1.,  1.],
            [ 1.,  1.,  1.],
            [ 1.,  1.,  1.]])
    
  2. use numpy.array to modify A. Doesn't work because you are modifying a copy

    >>> numpy.array(A)[2]=2
    >>> A
    matrix([[ 1.,  1.,  1.],
            [ 1.,  1.,  1.],
            [ 1.,  1.,  1.]])
    
  3. use numpy.asarray to modify A. It worked because you are modifying A itself

    >>> numpy.asarray(A)[2]=2
    >>> A
    matrix([[ 1.,  1.,  1.],
            [ 1.,  1.,  1.],
            [ 2.,  2.,  2.]])
    

Hope this helps!

Run a PostgreSQL .sql file using command line arguments

You can open a command prompt and run as administrator. Then type

../bin>psql -f c:/...-h localhost -p 5432 -d databasename -U "postgres"

Password for user postgres: will show up.

Type your password and enter. I couldn't see the password what I was typing, but this time when I press enter it worked. Actually I was loading data into the database.

How should I unit test multithreaded code?

Another way to (kinda) test threaded code, and very complex systems in general is through Fuzz Testing. It's not great, and it won't find everything, but its likely to be useful and its simple to do.

Quote:

Fuzz testing or fuzzing is a software testing technique that provides random data("fuzz") to the inputs of a program. If the program fails (for example, by crashing, or by failing built-in code assertions), the defects can be noted. The great advantage of fuzz testing is that the test design is extremely simple, and free of preconceptions about system behavior.

...

Fuzz testing is often used in large software development projects that employ black box testing. These projects usually have a budget to develop test tools, and fuzz testing is one of the techniques which offers a high benefit to cost ratio.

...

However, fuzz testing is not a substitute for exhaustive testing or formal methods: it can only provide a random sample of the system's behavior, and in many cases passing a fuzz test may only demonstrate that a piece of software handles exceptions without crashing, rather than behaving correctly. Thus, fuzz testing can only be regarded as a bug-finding tool rather than an assurance of quality.

How can I convert a comma-separated string to an array?

As @oportocala mentions, an empty string will not result in the expected empty array.

So to counter, do:

str
.split(',')
.map(entry => entry.trim())
.filter(entry => entry)

For an array of expected integers, do:

str
.split(',')
.map(entry => parseInt(entry))
.filter(entry => typeof entry ==='number')

How to center a navigation bar with CSS or HTML?

#nav ul {
    display: inline-block;
    list-style-type: none;
}

It should work, I tested it in your site.

enter image description here

Simple post to Web Api

It's been quite sometime since I asked this question. Now I understand it more clearly, I'm going to put a more complete answer to help others.

In Web API, it's very simple to remember how parameter binding is happening.

  • if you POST simple types, Web API tries to bind it from the URL
  • if you POST complex type, Web API tries to bind it from the body of the request (this uses a media-type formatter).

  • If you want to bind a complex type from the URL, you'll use [FromUri] in your action parameter. The limitation of this is down to how long your data going to be and if it exceeds the url character limit.

    public IHttpActionResult Put([FromUri] ViewModel data) { ... }

  • If you want to bind a simple type from the request body, you'll use [FromBody] in your action parameter.

    public IHttpActionResult Put([FromBody] string name) { ... }

as a side note, say you are making a PUT request (just a string) to update something. If you decide not to append it to the URL and pass as a complex type with just one property in the model, then the data parameter in jQuery ajax will look something like below. The object you pass to data parameter has only one property with empty property name.

var myName = 'ABC';
$.ajax({url:.., data: {'': myName}});

and your web api action will look something like below.

public IHttpActionResult Put([FromBody] string name){ ... }

This asp.net page explains it all. http://www.asp.net/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api

How do I declare and assign a variable on a single line in SQL

You've nearly got it:

DECLARE @myVariable nvarchar(max) = 'hello world';

See here for the docs

For the quotes, SQL Server uses apostrophes, not quotes:

DECLARE @myVariable nvarchar(max) = 'John said to Emily "Hey there Emily"';

Use double apostrophes if you need them in a string:

DECLARE @myVariable nvarchar(max) = 'John said to Emily ''Hey there Emily''';

Spring get current ApplicationContext

I think this link demonstrates the best way to get application context anywhere, even in the non-bean class. I find it very useful. Hope its the same for you. The below is the abstract code of it

Create a new class ApplicationContextProvider.java

package com.java2novice.spring;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class ApplicationContextProvider implements ApplicationContextAware{

    private static ApplicationContext context;

    public static ApplicationContext getApplicationContext() {
        return context;
    }

    @Override
    public void setApplicationContext(ApplicationContext ac)
            throws BeansException {
        context = ac;
    }
}

Add an entry in application-context.xml

<bean id="applicationContextProvider"
                        class="com.java2novice.spring.ApplicationContextProvider"/>

In annotations case (instead of application-context.xml)

@Component
public class ApplicationContextProvider implements ApplicationContextAware{
...
}

Get the context like this

TestBean tb = ApplicationContextProvider.getApplicationContext().getBean("testBean", TestBean.class);

Cheers!!

How can I generate Unix timestamps?

The unix 'date' command is surprisingly versatile.

date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"

Takes the output of date, which will be in the format defined by -f, and then prints it out (-j says don't attempt to set the date) in the form +%s, seconds since epoch.

ImportError: No module named dateutil.parser

If you are using Pipenv, you may need to add this to your Pipfile:

[packages]
python-dateutil = "*"

select count(*) from select

You're missing a FROM and you need to give the subquery an alias.

SELECT COUNT(*) FROM 
(
  SELECT DISTINCT a.my_id, a.last_name, a.first_name, b.temp_val
   FROM dbo.Table_A AS a 
   INNER JOIN dbo.Table_B AS b 
   ON a.a_id = b.a_id
) AS subquery;

Jquery - Uncaught TypeError: Cannot use 'in' operator to search for '324' in

You have a JSON string, not an object. Tell jQuery that you expect a JSON response and it will parse it for you. Either use $.getJSON instead of $.get, or pass the dataType argument to $.get:

$.get(
    'index.php?r=admin/post/ajax',
    {"parentCatId":parentCatId},
    function(data){                     
        $.each(data, function(key, value){
            console.log(key + ":" + value)
        })
    },
    'json'
);

Where is the Query Analyzer in SQL Server Management Studio 2008 R2?

Yes there is one and it is inside the SQLServer management studio. Unlike the previous versions I think. Follow these simple steps.

1)Right click on a database in the Object explorer 2)Selected New Query from the popup menu 3)Query Analyzer will be opened.

Enjoy work.

How to add custom method to Spring Data JPA

I use SimpleJpaRepository as the base class of repository implementation and add custom method in the interface,eg:

public interface UserRepository  {
    User FindOrInsert(int userId);
}

@Repository
public class UserRepositoryImpl extends SimpleJpaRepository implements UserRepository {

    private RedisClient redisClient;

    public UserRepositoryImpl(RedisClient redisClient, EntityManager em) {
        super(User.class, em);
        this.redisClient = redisClient;
    }


@Override
public User FindOrInsert(int userId) {

    User u = redisClient.getOrSet("test key.. User.class, () -> {
        Optional<User> ou = this.findById(Integer.valueOf(userId));
        return ou.get();
    });
    …………
    return u;
}

Difference between .dll and .exe?

Two things: the extension and the header flag stored in the file.

Both files are PE files. Both contain the exact same layout. A DLL is a library and therefore can not be executed. If you try to run it you'll get an error about a missing entry point. An EXE is a program that can be executed. It has an entry point. A flag inside the PE header indicates which file type it is (irrelevant of file extension). The PE header has a field where the entry point for the program resides. In DLLs it isn't used (or at least not as an entry point).

One minor difference is that in most cases DLLs have an export section where symbols are exported. EXEs should never have an export section since they aren't libraries but nothing prevents that from happening. The Win32 loader doesn't care either way.

Other than that they are identical. So, in summary, EXEs are executable programs while DLLs are libraries loaded into a process and contain some sort of useful functionality like security, database access or something.

phpinfo() is not working on my CentOS server

Be sure that the tag "php" is stick in the code like this:

?php phpinfo(); ?>

Not like this:

? php phpinfo(); ?>

OR the server will treat it as a (normal word), so the server will not understand the language you are writing to deal with it so it will be blank.

I know it's a silly error ...but it happened ^_^

How does the JPA @SequenceGenerator annotation work

Now, back to your questions:

Q1. Does this sequence generator make use of the database's increasing numeric value generating capability or generates the number on its own?

By using the GenerationType.SEQUENCE strategy on the @GeneratedValue annotation, the JPA provider will try to use a database sequence object of the underlying database that supports this feature (e.g., Oracle, SQL Server, PostgreSQL, MariaDB).

If you are using MySQL, which doesn't support database sequence objects, then Hibernate is going to fall back to using the GenerationType.TABLE instead, which is undesirable since the TABLE generation performs badly.

So, don't use the GenerationType.SEQUENCE strategy with MySQL.

Q2. If JPA uses a database auto-increment feature, then will it work with datastores that don't have auto-increment feature?

I assume you are talking about the GenerationType.IDENTITY when you say database auto-increment feature.

To use an AUTO_INCREMENT or IDENTITY column, you need to use the GenerationType.IDENTITYstrategy on the @GeneratedValue annotation.

Q3. If JPA generates numeric value on its own, then how does the JPA implementation know which value to generate next? Does it consult with the database first to see what value was stored last in order to generate the value (last + 1)?

The only time when the JPA provider generates values on its own is when you are using the sequence-based optimizers, like:

These optimizers are meat to reduce the number of database sequence calls, so they multiply the number of identifier values that can be generated using a single database sequence call.

To avoid conflicts between Hibernate identifier optimizers and other 3rd-party clients, you should use pooled or pooled-lo instead of hi/lo. Even if you are using a legacy application that was designed to use hi/lo, you can migrate to the pooled or pooled-lo optimizers.

Q4. Please also shed some light on sequenceName and allocationSize properties of @SequenceGenerator annotation.

The sequenceName attribute defines the database sequence object to be used to generate the identifier values. IT's the object you created using the CREATE SEQUENCE DDL statement.

So, if you provide this mapping:

@Id
@GeneratedValue(
    strategy = GenerationType.SEQUENCE,
    generator = "seq_post"
)
@SequenceGenerator(
    name = "seq_post"
)
private Long id;

Hibernate is going to use the seq_post database object to generate the identifier values:

SELECT nextval('hibernate_sequence')

The allocationSize defines the identifier value multiplier, and if you provide a value that's greater than 1, then Hibernate is going to use the pooled optimizer, to reduce the number of database sequence calls.

So, if you provide this mapping:

@Id
@GeneratedValue(
    strategy = GenerationType.SEQUENCE,
    generator = "seq_post"
)
@SequenceGenerator(
    name = "seq_post",
    allocationSize = 5
)
private Long id;

Then, when you persist 5 entities:

for (int i = 1; i <= 5; i++) {
    entityManager.persist(
        new Post().setTitle(
            String.format(
                "High-Performance Java Persistence, Part %d",
                i
            )
        )
    );
}

Only 2 database sequence calls will be executed, instead of 5:

SELECT nextval('hibernate_sequence')
SELECT nextval('hibernate_sequence')
 
INSERT INTO post (title, id)
VALUES ('High-Performance Java Persistence, Part 1', 1)
 
INSERT INTO post (title, id)
VALUES ('High-Performance Java Persistence, Part 2', 2)
 
INSERT INTO post (title, id)
VALUES ('High-Performance Java Persistence, Part 3', 3)
 
INSERT INTO post (title, id)
VALUES ('High-Performance Java Persistence, Part 4', 4)
 
INSERT INTO post (title, id)
VALUES ('High-Performance Java Persistence, Part 5', 5)

Importing Pandas gives error AttributeError: module 'pandas' has no attribute 'core' in iPython Notebook

"Have you tried turning it off and on again?" (Roy of The IT crowd)

This happened to me today, which is why I ended up to this page. Seeing that error was weird since, recently, I have not made any changes in my Python environment. Interestingly, I observed that if I open a new notebook and import pandas I would not get the same error message. So, I did shutdown the troublesome notebook and started it again and voila it is working again!

Even though this solved the problem (at least for me), I cannot readily come up with an explanation as to why it happened in the first place!

Best way to use Google's hosted jQuery, but fall back to my hosted library on Google fail

Google Hosted jQuery

  • If you care about older browsers, primarily versions of IE prior to IE9, this is the most widely compatible jQuery version
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
  • If you don’t care about oldIE, this one is smaller and faster:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>

Backup/Fallback Plan!

  • Either way, you should use a fallback to local just in case the Google CDN fails (unlikely) or is blocked in a location that your users access your site from (slightly more likely), like Iran or sometimes China.
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script>if (!window.jQuery) { document.write('<script src="/path/to/your/jquery"><\/script>'); }
</script>

Reference: http://websitespeedoptimizations.com/ContentDeliveryNetworkPost.aspx

How to get the request parameters in Symfony 2?

For symfony 4 users:

$query = $request->query->get('query');

Does a VPN Hide my Location on Android?

Your question can be conveniently divided into several parts:

Does a VPN hide location? Yes, he is capable of this. This is not about GPS determining your location. If you try to change the region via VPN in an application that requires GPS access, nothing will work. However, sites define your region differently. They get an IP address and see what country or region it belongs to. If you can change your IP address, you can change your region. This is exactly what VPNs can do.

How to hide location on Android? There is nothing difficult in figuring out how to set up a VPN on Android, but a couple of nuances still need to be highlighted. Let's start with the fact that not all Android VPNs are created equal. For example, VeePN outperforms many other services in terms of efficiency in circumventing restrictions. It has 2500+ VPN servers and a powerful IP and DNS leak protection system.

You can easily change the location of your Android device by using a VPN. Follow these steps for any device model (Samsung, Sony, Huawei, etc.):

  1. Download and install a trusted VPN.

  2. Install the VPN on your Android device.

  3. Open the application and connect to a server in a different country.

  4. Your Android location will now be successfully changed!

Is it legal? Yes, changing your location on Android is legal. Likewise, you can change VPN settings in Microsoft Edge on your PC, and all this is within the law. VPN allows you to change your IP address, safeguarding your privacy and protecting your actual location from being exposed. However, VPN laws may vary from country to country. There are restrictions in some regions.

Brief summary: Yes, you can change your region on Android and a VPN is a necessary assistant for this. It's simple, safe and legal. Today, VPN is the best way to change the region and unblock sites with regional restrictions.

php random x digit number

This function works perfectly with no repeats and desired number of digits.

$digits = '';
function randomDigits($length){
    $numbers = range(0,9);
    shuffle($numbers);
    for($i = 0; $i < $length; $i++){
        global $digits;
        $digits .= $numbers[$i];
    }
    return $digits;
}

You can call the function and pass the number of digits for example:

randomDigits(4);

sample results:

4957 8710 6730 6082 2987 2041 6721

Original script got from this gist

How to redirect the output of the time command to a file in Linux?

If you are using GNU time instead of the bash built-in, try

time -o outfile command

(Note: GNU time formats a little differently than the bash built-in).

Table cell widths - fixing width, wrapping/truncating long words

As long as you fix the width of the table itself and set the table-layout property, this is pretty simple :

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <style type="text/css">
        td { width: 30px; overflow: hidden; }
        table { width : 90px; table-layout: fixed; }
    </style>
</head>
<body>

    <table border="2">
        <tr>
            <td>word</td>
            <td>two words</td>
            <td>onereallylongword</td>

        </tr>
    </table>
</body>
</html>

I've tested this in IE6 and 7 and it seems to work fine.

Unbalanced calls to begin/end appearance transitions for <UITabBarController: 0x197870>

Actually you need to wait till the push animation ends. So you can delegate UINavigationController and prevent pushing till the animation ends.

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated{
    waitNavigation = NO;
}


-(void)showGScreen:(id)gvc{

    if (!waitNavigation) {
        waitNavigation = YES;
        [_nav popToRootViewControllerAnimated:NO];
        [_nav pushViewController:gvc animated:YES];
    }
}

No function matches the given name and argument types

In my particular case the function was actually missing. The error message is the same. I am using the Postgresql plugin PostGIS and I had to reinstall that for whatever reason.

SQL Server : How to test if a string has only digit characters

Method that will work. The way it is used above will not work.

declare @str varchar(50)='79136'

select 
  case 
    when  @str LIKE replicate('[0-9]',LEN(@str)) then 1 
    else 0 
  end

declare @str2 varchar(50)='79D136'

select 
  case 
    when  @str2 LIKE replicate('[0-9]',LEN(@str)) then 1 
    else 0 
  end

Set start value for column with autoincrement

In the Table Designer on SQL Server Management Studio you can set the where the auto increment will start. Right-click on the table in Object Explorer and choose Design, then go to the Column Properties for the relevant column:

Here the autoincrement will start at 760

How to change button background image on mouseOver?

You can create a class based on a Button with specific images for MouseHover and MouseDown like this:

public class AdvancedImageButton : Button {

public Image HoverImage { get; set; }
public Image PlainImage { get; set; }
public Image PressedImage { get; set; }

protected override void OnMouseEnter(System.EventArgs e)
{
  base.OnMouseEnter(e);
  if (HoverImage == null) return;
  if (PlainImage == null) PlainImage = base.Image;
  base.Image = HoverImage;
}

protected override void OnMouseLeave(System.EventArgs e)
{
  base.OnMouseLeave(e);
  if (HoverImage == null) return;
  base.Image = PlainImage;
}

protected override void OnMouseDown(MouseEventArgs e)
{
  base.OnMouseDown(e);
  if (PressedImage == null) return;
  if (PlainImage == null) PlainImage = base.Image;
  base.Image = PressedImage;
}

}

This solution has a small drawback that I am sure can be fixed: when you need for some reason change the Image property, you will also have to change the PlainImage property also.

How to check if PHP array is associative or sequential?

Checking if array has all assoc-keys. With using stdClass & get_object_vars ^):

$assocArray = array('fruit1' => 'apple', 
                    'fruit2' => 'orange', 
                    'veg1' => 'tomato', 
                    'veg2' => 'carrot');

$assoc_object = (object) $assocArray;
$isAssoc = (count($assocArray) === count (get_object_vars($assoc_object)));  
var_dump($isAssoc); // true

Why? Function get_object_vars returns only accessible properties (see more about what is occuring during converting array to object here). Then, just logically: if count of basic array's elements equals count of object's accessible properties - all keys are assoc.

Few tests:

$assocArray = array('apple', 'orange', 'tomato', 'carrot');
$assoc_object = (object) $assocArray; 
$isAssoc = (count($assocArray) === count (get_object_vars($assoc_object)));
var_dump($isAssoc); // false 
//...

$assocArray = array( 0 => 'apple', 'orange', 'tomato', '4' => 'carrot');
$assoc_object = (object) $assocArray; 
$isAssoc = (count($assocArray) === count (get_object_vars($assoc_object)));
var_dump($isAssoc); // false 

//... 
$assocArray = array('fruit1' => 'apple', 
                    NULL => 'orange', 
                    'veg1' => 'tomato', 
                    'veg2' => 'carrot');

$assoc_object = (object) $assocArray;
$isAssoc = (count($assocArray) === count (get_object_vars($assoc_object)));  
var_dump($isAssoc); //false

Etc.

Cannot find R.layout.activity_main

or you can write

import.R.layout // at the top

It will work for sure

What is callback in Android?

Callback can be very helpful in Java.

Using Callback you can notify another Class of an asynchronous action that has completed with success or error.

How do I concatenate const/literal strings in C?

You are trying to copy a string into an address that is statically allocated. You need to cat into a buffer.

Specifically:

...snip...

destination

Pointer to the destination array, which should contain a C string, and be large enough to contain the concatenated resulting string.

...snip...

http://www.cplusplus.com/reference/clibrary/cstring/strcat.html

There's an example here as well.

Bootstrap 3 Glyphicons CDN

An alternative would be to use Font-Awesome for icons:

Including Font-Awesome

Open Font-Awesome on CDNJS and copy the CSS url of the latest version:

<link rel="stylesheet" href="<url>">

Or in CSS

@import url("<url>");

For example (note, the version will change):

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.css">

Usage:

<i class="fa fa-bed"></i>

It contains a lot of icons!

Strtotime() doesn't work with dd/mm/YYYY format

I haven't found a better solution. You can use explode(), preg_match_all(), etc.

I have a static helper function like this

class Date {

    public static function ausStrToTime($str) {
        $dateTokens = explode('/', $str);
        return strtotime($dateTokens[1] . '/' . $dateTokens[0] . '/' . $dateTokens[2]); 

    }

}

There is probably a better name for that, but I use ausStrToTime() because it works with Australian dates (which I often deal with, being an Australian). A better name would probably be the standardised name, but I'm not sure what that is.

Using C++ filestreams (fstream), how can you determine the size of a file?

You can open the file using the ios::ate flag (and ios::binary flag), so the tellg() function will give you directly the file size:

ifstream file( "example.txt", ios::binary | ios::ate);
return file.tellg();

JavaScript code for getting the selected value from a combo box

I use this

var e = document.getElementById('ticket_category_clone').value;

Notice that you don't need the '#' character in javascript.

    function check () {

    var str = document.getElementById('ticket_category_clone').value;

      if (str==="Hardware")
      {
        SPICEWORKS.utils.addStyle('#ticket_c_hardware_clone{display: none !important;}');
      }

    }

SPICEWORKS.app.helpdesk.ready(check);?

The Web Application Project [...] is configured to use IIS. The Web server [...] could not be found.

I had this error, too. I thought everything was setup correctly, but I found out that one thing was missing: The host name I used for my project was not (yet) resolvable.

Since my app determines the current client's name from the host name I used a host name like clientname.mysuperapp.local for development. When I added the development host name to my hosts file, the project was loadable again. Obviously, I had to this anyway, but I haven't thought that VS checks the host name before loading the project.

Why can't overriding methods throw exceptions broader than the overridden method?

Java is giving you the choice to restrict exceptions in the parent class, because it's assuming the client will restrict what is caught. IMHO you should essentially never use this "feature", because your clients may need flexibility down the road.

Java is an old language that is poorly designed. Modern languages don't have such restrictions. The easiest way around this flaw is make your base class throw Exception always. Clients can throw more specific Exceptions but make your base classes really broad.

How to print a Groovy variable in Jenkins?

You shouldn't use ${varName} when you're outside of strings, you should just use varName. Inside strings you use it like this; echo "this is a string ${someVariable}";. Infact you can place an general java expression inside of ${...}; echo "this is a string ${func(arg1, arg2)}.

Ascii/Hex convert in bash

echo -n Aa | hexdump -e '/1 "%02x"'; echo

PHP Session Destroy on Log Out Button

First give the link of logout.php page in that logout button.In that page make the code which is given below:

Here is the code:

<?php
 session_start();
 session_destroy();
?>

When the session has started, the session for the last/current user has been started, so don't need to declare the username. It will be deleted automatically by the session_destroy method.

jquery's append not working with svg element?

A much simpler way is to just generate your SVG into a string, create a wrapper HTML element and insert the svg string into the HTML element using $("#wrapperElement").html(svgString). This works just fine in Chrome and Firefox.

wait process until all subprocess finish?

subprocess.call

Automatically waits , you can also use:

p1.wait()

How to change screen resolution of Raspberry Pi

TV Sony Bravia KLV-32T550A Below mention config works greatly You should add the following into the /boot/config.txt to force the output to HDMI and set the

resolution 82   1920x1080   60Hz    1080p

hdmi_ignore_edid=0xa5000080
hdmi_force_hotplug=1
hdmi_boost=7
hdmi_group=2
hdmi_mode=82
hdmi_drive=1

How to enable PHP's openssl extension to install Composer?

For WAMP server, comment given by "Enrique" solved my problem.

wamp is using this php.ini:

c:\wamp\bin\apache\Apache2.4.4\bin\php.ini

But composer is using PHP from CLI, and hence it's reading this file:

c:\wamp\bin\php\php5.4.12\php.ini (so you need to enable openssl there)

For composer you will have to enable extension in

c:\wamp\bin\php\php5.4.12\php.ini

Change:

;extension=php_openssl.dll 

to

extension=php_openssl.dll

What does ':' (colon) do in JavaScript?

That's JSON, or JavaScript Object Notation. It's a quick way of describing an object, or a hash map. The thing before the colon is the property name, and the thing after the colon is its value. So in this example, there's a property "r", whose value is whatever's in the variable r. Same for t.

How to get main window handle from process id?

Old question but appears to have a lot of traffic, here is a simple solution:

IntPtr GetMainWindowHandle(IntPtr aHandle) {
        return System.Diagnostics.Process.GetProcessById(aHandle.ToInt32()).MainWindowHandle;
}

variable or field declared void

It for example happens in this case here:

void initializeJSP(unknownType Experiment);

Try using std::string instead of just string (and include the <string> header). C++ Standard library classes are within the namespace std::.

How to make Toolbar transparent?

I implemented translucent Toolbar by creating two Theme.AppCompat.Light.NoActionBar themes and setting colorPrimary attribute to transparent color.

1) Create one theme for opaque Toolbar:

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

    <!-- Toolbar background color -->
    <item name="colorPrimary">#ff212cff</item>

</style>

Second theme for transparent/overlay Toolbar:

<style name="AppTheme.Overlay" parent="AppTheme">
    <item name="colorPrimary">@color/transparent</item>
</style>

2) In your activity layout, put Toolbar behind content so it can be displayed in front of it:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <fragment
        android:id="@+id/container"
        android:name="com.test.CustomFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:minHeight="?attr/actionBarSize"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"/>

</RelativeLayout>

3) Apply the transparent theme to your acivity in AndroidManifest.xml

    <activity
        android:name="com.test.TransparentActivity"
        android:parentActivityName="com.test.HomeActivity"
        android:theme="@style/AppTheme.Overlay" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.test.HomeActivity" />
    </activity>

Differences between Html.TextboxFor and Html.EditorFor in MVC and Razor

TextBoxFor: It will render like text input html element corresponding to specified expression. In simple word it will always render like an input textbox irrespective datatype of the property which is getting bind with the control.

EditorFor: This control is bit smart. It renders HTML markup based on the datatype of the property. E.g. suppose there is a boolean property in model. To render this property in the view as a checkbox either we can use CheckBoxFor or EditorFor. Both will be generate the same markup.

What is the advantage of using EditorFor?

As we know, depending on the datatype of the property it generates the html markup. So suppose tomorrow if we change the datatype of property in the model, no need to change anything in the view. EditorFor control will change the html markup automatically.

How can I programmatically determine if my app is running in the iphone simulator?

if nothing worked, try this

public struct Platform {

    public static var isSimulator: Bool {
        return TARGET_OS_SIMULATOR != 0 // Use this line in Xcode 7 or newer
    }

}

position fixed header in html

The position :fixed is differ from the other layout. Once you fixed the position for your header, keep in mind that you have to set the margin-top for the content div.

How to lay out Views in RelativeLayout programmatically?

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);

        final RelativeLayout relativeLayout = new RelativeLayout(this);
        final TextView tv1 = new TextView(this);
        tv1.setText("tv1 is here");
        // Setting an ID is mandatory.
        tv1.setId(View.generateViewId());
        relativeLayout.addView(tv1);


        final TextView tv2 = new TextView(this);
        tv2.setText("tv2 is here");

        // We are defining layout params for tv2 which will be added to its  parent relativelayout.
        // The type of the LayoutParams depends on the parent type.
        RelativeLayout.LayoutParams tv2LayoutParams = new  RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);

        //Also, we want tv2 to appear below tv1, so we are adding rule to tv2LayoutParams.
        tv2LayoutParams.addRule(RelativeLayout.BELOW, tv1.getId());

        //Now, adding the child view tv2 to relativelayout, and setting tv2LayoutParams to be set on view tv2.
        relativeLayout.addView(tv2);
        tv2.setLayoutParams(tv2LayoutParams);
        //Or we can combined the above two steps in one line of code
        //relativeLayout.addView(tv2, tv2LayoutParams);

        this.setContentView(relativeLayout);
    }

}

Programmatically set TextBlock Foreground Color

Foreground needs a Brush, so you can use

textBlock.Foreground = Brushes.Navy;

If you want to use the color from RGB or ARGB then

textBlock.Foreground = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(100, 255, 125, 35)); 

or

textBlock.Foreground = new System.Windows.Media.SolidColorBrush(Colors.Navy); 

To get the Color from Hex

textBlock.Foreground = new System.Windows.Media.SolidColorBrush((Color)ColorConverter.ConvertFromString("#FFDFD991")); 

What is the Java equivalent of PHP var_dump?

I like to use GSON because it's often already a dependency of the type of projects I'm working on:

public static String getDump(Object o) {
    return new GsonBuilder().setPrettyPrinting().create().toJson(o);
}

Or substitute GSON for any other JSON library you use.

Dynamically add script tag with src that may include document.write

This Is Work For Me.

You Can Check It.

_x000D_
_x000D_
var script_tag = document.createElement('script');_x000D_
script_tag.setAttribute('src','https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js');_x000D_
document.head.appendChild(script_tag);_x000D_
window.onload = function() {_x000D_
    if (window.jQuery) {  _x000D_
        // jQuery is loaded  _x000D_
        alert("ADD SCRIPT TAG ON HEAD!");_x000D_
    } else {_x000D_
        // jQuery is not loaded_x000D_
        alert("DOESN'T ADD SCRIPT TAG ON HEAD");_x000D_
    }_x000D_
}
_x000D_
_x000D_
_x000D_

Check if number is decimal

This is a more tolerate way to handle this with user input. This regex will match both "100" or "100.1" but doesn't allow for negative numbers.

/^(\d+)(\.\d+)?$/

Android: Storing username and password?

You should use the Android AccountManager. It's purpose-built for this scenario. It's a little bit cumbersome but one of the things it does is invalidate the local credentials if the SIM card changes, so if somebody swipes your phone and throws a new SIM in it, your credentials won't be compromised.

This also gives the user a quick and easy way to access (and potentially delete) the stored credentials for any account they have on the device, all from one place.

SampleSyncAdapter (like @Miguel mentioned) is an example that makes use of stored account credentials.

"column not allowed here" error in INSERT statement

Try using varchar2 instead of varchar and use this :

INSERT INTO LOCATION VALUES('PQ95VM','HAPPY_STREET','FRANCE');

PHP filesize MB/KB conversion

Here is a sample:

<?php
// Snippet from PHP Share: http://www.phpshare.org

    function formatSizeUnits($bytes)
    {
        if ($bytes >= 1073741824)
        {
            $bytes = number_format($bytes / 1073741824, 2) . ' GB';
        }
        elseif ($bytes >= 1048576)
        {
            $bytes = number_format($bytes / 1048576, 2) . ' MB';
        }
        elseif ($bytes >= 1024)
        {
            $bytes = number_format($bytes / 1024, 2) . ' KB';
        }
        elseif ($bytes > 1)
        {
            $bytes = $bytes . ' bytes';
        }
        elseif ($bytes == 1)
        {
            $bytes = $bytes . ' byte';
        }
        else
        {
            $bytes = '0 bytes';
        }

        return $bytes;
}
?>

What causes the error "_pickle.UnpicklingError: invalid load key, ' '."?

pickling is recursive, not sequential. Thus, to pickle a list, pickle will start to pickle the containing list, then pickle the first element… diving into the first element and pickling dependencies and sub-elements until the first element is serialized. Then moves on to the next element of the list, and so on, until it finally finishes the list and finishes serializing the enclosing list. In short, it's hard to treat a recursive pickle as sequential, except for some special cases. It's better to use a smarter pattern on your dump, if you want to load in a special way.

The most common pickle, it to pickle everything with a single dump to a file -- but then you have to load everything at once with a single load. However, if you open a file handle and do multiple dump calls (e.g. one for each element of the list, or a tuple of selected elements), then your load will mirror that… you open the file handle and do multiple load calls until you have all the list elements and can reconstruct the list. It's still not easy to selectively load only certain list elements, however. To do that, you'd probably have to store your list elements as a dict (with the index of the element or chunk as the key) using a package like klepto, which can break up a pickled dict into several files transparently, and enables easy loading of specific elements.

Saving and loading multiple objects in pickle file?

How do I compare two strings in Perl?

The obvious subtext of this question is:

why can't you just use == to check if two strings are the same?

Perl doesn't have distinct data types for text vs. numbers. They are both represented by the type "scalar". Put another way, strings are numbers if you use them as such.

if ( 4 == "4" ) { print "true"; } else { print "false"; }
true

if ( "4" == "4.0" ) { print "true"; } else { print "false"; }
true

print "3"+4
7

Since text and numbers aren't differentiated by the language, we can't simply overload the == operator to do the right thing for both cases. Therefore, Perl provides eq to compare values as text:

if ( "4" eq "4.0" ) { print "true"; } else { print "false"; }
false

if ( "4.0" eq "4.0" ) { print "true"; } else { print "false"; }
true

In short:

  • Perl doesn't have a data-type exclusively for text strings
  • use == or !=, to compare two operands as numbers
  • use eq or ne, to compare two operands as text

There are many other functions and operators that can be used to compare scalar values, but knowing the distinction between these two forms is an important first step.

Python loop that also accesses previous and next values

Solutions until now only deal with lists, and most are copying the list. In my experience a lot of times that isn't possible.

Also, they don't deal with the fact that you can have repeated elements in the list.

The title of your question says "Previous and next values inside a loop", but if you run most answers here inside a loop, you'll end up iterating over the entire list again on each element to find it.

So I've just created a function that. using the itertools module, splits and slices the iterable, and generates tuples with the previous and next elements together. Not exactly what your code does, but it is worth taking a look, because it can probably solve your problem.

from itertools import tee, islice, chain, izip

def previous_and_next(some_iterable):
    prevs, items, nexts = tee(some_iterable, 3)
    prevs = chain([None], prevs)
    nexts = chain(islice(nexts, 1, None), [None])
    return izip(prevs, items, nexts)

Then use it in a loop, and you'll have previous and next items in it:

mylist = ['banana', 'orange', 'apple', 'kiwi', 'tomato']

for previous, item, nxt in previous_and_next(mylist):
    print "Item is now", item, "next is", nxt, "previous is", previous

The results:

Item is now banana next is orange previous is None
Item is now orange next is apple previous is banana
Item is now apple next is kiwi previous is orange
Item is now kiwi next is tomato previous is apple
Item is now tomato next is None previous is kiwi

It'll work with any size list (because it doesn't copy the list), and with any iterable (files, sets, etc). This way you can just iterate over the sequence, and have the previous and next items available inside the loop. No need to search again for the item in the sequence.

A short explanation of the code:

  • tee is used to efficiently create 3 independent iterators over the input sequence
  • chain links two sequences into one; it's used here to append a single-element sequence [None] to prevs
  • islice is used to make a sequence of all elements except the first, then chain is used to append a None to its end
  • There are now 3 independent sequences based on some_iterable that look like:
    • prevs: None, A, B, C, D, E
    • items: A, B, C, D, E
    • nexts: B, C, D, E, None
  • finally izip is used to change 3 sequences into one sequence of triplets.

Note that izip stops when any input sequence gets exhausted, so the last element of prevs will be ignored, which is correct - there's no such element that the last element would be its prev. We could try to strip off the last elements from prevs but izip's behaviour makes that redundant

Also note that tee, izip, islice and chain come from the itertools module; they operate on their input sequences on-the-fly (lazily), which makes them efficient and doesn't introduce the need of having the whole sequence in memory at once at any time.

In python 3, it will show an error while importing izip,you can use zip instead of izip. No need to import zip, it is predefined in python 3 - source

Python dictionary get multiple values

If you have pandas installed you can turn it into a series with the keys as the index. So something like

import pandas as pd

s = pd.Series(my_dict)

s[['key1', 'key3', 'key2']]

How to position text over an image in css

How about something like this: http://jsfiddle.net/EgLKV/3/

Its done by using position:absolute and z-index to place the text over the image.

_x000D_
_x000D_
#container {_x000D_
  height: 400px;_x000D_
  width: 400px;_x000D_
  position: relative;_x000D_
}_x000D_
#image {_x000D_
  position: absolute;_x000D_
  left: 0;_x000D_
  top: 0;_x000D_
}_x000D_
#text {_x000D_
  z-index: 100;_x000D_
  position: absolute;_x000D_
  color: white;_x000D_
  font-size: 24px;_x000D_
  font-weight: bold;_x000D_
  left: 150px;_x000D_
  top: 350px;_x000D_
}
_x000D_
<div id="container">_x000D_
  <img id="image" src="http://www.noao.edu/image_gallery/images/d4/androa.jpg" />_x000D_
  <p id="text">_x000D_
    Hello World!_x000D_
  </p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

java.lang.ClassNotFoundException: org.springframework.core.io.Resource

I received same error despite jar being in lib directory & added to deployment assembly in Eclipse.

So I doubted two things ,

1.Some Weblogic cache issue - as this app was deployed before & I was trying to redeploy after some changes

2.Jar itself is corrupt due to partial download etc

So I re downloaded the jar & deleted everything in directory - ..\Oracle_Home\user_projects\domains\base_domain\lib and redeployed again & all went well.

Hiding button using jQuery

It depends on the jQuery selector that you use. Since id should be unique within the DOM, the first one would be simple:

$('#Comanda').hide();

The second one might require something more, depending on the other elements and how to uniquely identify it. If the name of that particular input is unique, then this would work:

$('input[name="Vizualizeaza"]').hide();

Firebase Permission Denied

Go to the "Database" option you mentioned.

  1. There on the Blue Header you'll find a dropdown which says Cloud Firestore Beta
  2. Change it to "Realtime database"
  3. Go to Rules and set .write .read both to true

Copied from here.

Running an executable in Mac Terminal

To run an executable in mac

1). Move to the path of the file:

cd/PATH_OF_THE_FILE

2). Run the following command to set the file's executable bit using the chmod command:

chmod +x ./NAME_OF_THE_FILE

3). Run the following command to execute the file:

./NAME_OF_THE_FILE

Once you have run these commands, going ahead you just have to run command 3, while in the files path.

AngularJS: How to clear query parameters in the URL?

I ended up getting the answer from AngularJS forum. See this thread for details


The link is to a Google Groups thread, which is difficult to read and doesn't provide a clear answer. To remove URL parameters use

$location.url($location.path());

Could not install Gradle distribution from 'https://services.gradle.org/distributions/gradle-2.1-all.zip'

https://services.gradle.org/distributions/gradle-2.1-all.zip

open this link in the browser and download the zip file and extract it to folder

Before extraction please delete the old folder whose name ends gradle-2.1-all and then you can start extracting

if you are window user extract it to this folder

C:\Users{Your-Name}.gradle\wrapper\dists

after that just restart your android studio. I hope it works it works for me .

Is it possible to select the last n items with nth-child?

:nth-last-child(-n+2) should do the trick

convert NSDictionary to NSString

if you like to use for URLRequest httpBody

extension Dictionary {

    func toString() -> String? {
        return (self.compactMap({ (key, value) -> String in
            return "\(key)=\(value)"
        }) as Array).joined(separator: "&")
    }

}

// print: Fields=sdad&ServiceId=1222

What is the advantage of using heredoc in PHP?

Some IDEs highlight the code in heredoc strings automatically - which makes using heredoc for XML or HTML visually appealing.

I personally like it for longer parts of i.e. XML since I don't have to care about quoting quote characters and can simply paste the XML.

How does ApplicationContextAware work in Spring?

Spring source code to explain how ApplicationContextAware work
when you use ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
In AbstractApplicationContext class,the refresh() method have the following code:

// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);

enter this method,beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this)); will add ApplicationContextAwareProcessor to AbstractrBeanFactory.

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        // Tell the internal bean factory to use the context's class loader etc.
        beanFactory.setBeanClassLoader(getClassLoader());
        beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
        beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
        // Configure the bean factory with context callbacks.
        beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
...........

When spring initialize bean in AbstractAutowireCapableBeanFactory, in method initializeBean,call applyBeanPostProcessorsBeforeInitialization to implement the bean post process. the process include inject the applicationContext.

@Override
    public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
            throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
            result = beanProcessor.postProcessBeforeInitialization(result, beanName);
            if (result == null) {
                return result;
            }
        }
        return result;
    }

when BeanPostProcessor implement Objectto execute the postProcessBeforeInitialization method,for example ApplicationContextAwareProcessor that added before.

private void invokeAwareInterfaces(Object bean) {
        if (bean instanceof Aware) {
            if (bean instanceof EnvironmentAware) {
                ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());
            }
            if (bean instanceof EmbeddedValueResolverAware) {
                ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(
                        new EmbeddedValueResolver(this.applicationContext.getBeanFactory()));
            }
            if (bean instanceof ResourceLoaderAware) {
                ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
            }
            if (bean instanceof ApplicationEventPublisherAware) {
                ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
            }
            if (bean instanceof MessageSourceAware) {
                ((MessageSourceAware) bean).setMessageSource(this.applicationContext);
            }
            if (bean instanceof ApplicationContextAware) {
                ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
            }
        }
    }

PHP convert string to hex and hex to string

I only have half the answer, but I hope that it is useful as it adds unicode (utf-8) support

//decimal to unicode character
function unichr($dec) { 
  if ($dec < 128) { 
    $utf = chr($dec); 
  } else if ($dec < 2048) { 
    $utf = chr(192 + (($dec - ($dec % 64)) / 64)); 
    $utf .= chr(128 + ($dec % 64)); 
  } else { 
    $utf = chr(224 + (($dec - ($dec % 4096)) / 4096)); 
    $utf .= chr(128 + ((($dec % 4096) - ($dec % 64)) / 64)); 
    $utf .= chr(128 + ($dec % 64)); 
  } 
  return $utf;
}

To string

var_dump(unichr(hexdec('e641')));

Source: http://www.php.net/manual/en/function.chr.php#Hcom55978

Windows task scheduler error 101 launch failure code 2147943785

Had the same issue today. I added the user to:

Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Log on as a batch job

But was still getting the error. I found this post, and it turns out there's also this setting that I had to remove the user from (not sure how it got in there):

Administrative Tools -> Local Security Policy -> Local Policies -> User Rights Assignment -> Deny log on as a batch job

So just be aware that you may need to check both policies for the user.

How can I convert a string to upper- or lower-case with XSLT?

For ANSI character encoding:

 translate(//variable, 'ABCDEFGHIJKLMNOPQRSTUVWXYZÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞŸŽŠŒ', 'abcdefghijklmnopqrstuvwxyzàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿžšœ')

Https Connection Android

Sources that helped me get to work with my self signed certificate on my AWS Apache server and connect with HttpsURLConnection from android device:

SSL on aws instance - amazon tutorial on ssl
Android Security with HTTPS and SSL - creating your own trust manager on client for accepting your certificate
Creating self signed certificate - easy script for creating your certificates

Then I did the following:

  1. Made sure the server supports https (sudo yum install -y mod24_ssl)
  2. Put this script in a file create_my_certs.sh:
#!/bin/bash
FQDN=$1

# make directories to work from
mkdir -p server/ client/ all/

# Create your very own Root Certificate Authority
openssl genrsa \
  -out all/my-private-root-ca.privkey.pem \
  2048

# Self-sign your Root Certificate Authority
# Since this is private, the details can be as bogus as you like
openssl req \
  -x509 \
  -new \
  -nodes \
  -key all/my-private-root-ca.privkey.pem \
  -days 1024 \
  -out all/my-private-root-ca.cert.pem \
  -subj "/C=US/ST=Utah/L=Provo/O=ACME Signing Authority Inc/CN=example.com"

# Create a Device Certificate for each domain,
# such as example.com, *.example.com, awesome.example.com
# NOTE: You MUST match CN to the domain name or ip address you want to use
openssl genrsa \
  -out all/privkey.pem \
  2048

# Create a request from your Device, which your Root CA will sign
openssl req -new \
  -key all/privkey.pem \
  -out all/csr.pem \
  -subj "/C=US/ST=Utah/L=Provo/O=ACME Tech Inc/CN=${FQDN}"

# Sign the request from Device with your Root CA
openssl x509 \
  -req -in all/csr.pem \
  -CA all/my-private-root-ca.cert.pem \
  -CAkey all/my-private-root-ca.privkey.pem \
  -CAcreateserial \
  -out all/cert.pem \
  -days 500

# Put things in their proper place
rsync -a all/{privkey,cert}.pem server/
cat all/cert.pem > server/fullchain.pem         # we have no intermediates in this case
rsync -a all/my-private-root-ca.cert.pem server/
rsync -a all/my-private-root-ca.cert.pem client/
  1. Run bash create_my_certs.sh yourdomain.com
  2. Place the certificates in their proper place on the server (you can find configuration in /etc/httpd/conf.d/ssl.conf). All these should be set:
    SSLCertificateFile
    SSLCertificateKeyFile
    SSLCertificateChainFile
    SSLCACertificateFile

  3. Restart httpd using sudo service httpd restart and make sure httpd started:
    Stopping httpd: [ OK ]
    Starting httpd: [ OK ]

  4. Copy my-private-root-ca.cert to your android project assets folder

  5. Create your trust manager:

    SSLContext SSLContext;

    CertificateFactory cf = CertificateFactory.getInstance("X.509"); InputStream caInput = context.getAssets().open("my-private-root-ca.cert.pem"); Certificate ca; try { ca = cf.generateCertificate(caInput); } finally { caInput.close(); }

      // Create a KeyStore containing our trusted CAs
      String keyStoreType = KeyStore.getDefaultType();
      KeyStore keyStore = KeyStore.getInstance(keyStoreType);
      keyStore.load(null, null);
      keyStore.setCertificateEntry("ca", ca);
    
      // Create a TrustManager that trusts the CAs in our KeyStore
      String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
      TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
      tmf.init(keyStore);
    
      // Create an SSLContext that uses our TrustManager
      SSLContext = SSLContext.getInstance("TLS");
      SSSLContext.init(null, tmf.getTrustManagers(), null);
    
  6. And make the connection using HttpsURLConnection:

    HttpsURLConnection connection = (HttpsURLConnection) url.openConnection(); connection.setSSLSocketFactory(SSLContext.getSocketFactory());

  7. Thats it, try your https connection.

Want to upgrade project from Angular v5 to Angular v6

Upgrade from Angular v6 to Angular v7

Version 7 of Angular has been released Official Angular blog link. Visit official angular update guide https://update.angular.io for detailed information. These steps will work for basic angular 6 apps using Angular Material.

ng update @angular/cli 
ng update @angular/core
ng update @angular/material

Upgrade from Angular v5 to Angular v6

Version 6 of Angular has been released Official Angular blog link. I have mentioned general upgrade steps below, but before and after the update you need to make changes in your code to make it workable in v6, for that detailed information visit official website https://update.angular.io .

Upgrade Steps (largely taken from the official Angular Update Guide for a basic Angular app using Angular Material):

  1. Make sure NodeJS version is 8.9+ if not update it.

  2. Update Angular cli globally and locally, and migrate the old configuration .angular-cli.json to the new angular.json format by running the following:

    npm install -g @angular/cli  
    npm install @angular/cli  
    ng update @angular/cli
    
  3. Update all of your Angular framework packages to v6,and the correct version of RxJS and TypeScript by running the following:

    ng update @angular/core
    
  4. Update Angular Material to the latest version by running the following:

    ng update @angular/material
    
  5. RxJS v6 has major changes from v5, v6 brings backwards compatibility package rxjs-compat that will keep your applications working, but you should refactor TypeScript code so that it doesn't depend on rxjs-compat. To refactor TypeScript code run following:

    npm install -g rxjs-tslint   
    rxjs-5-to-6-migrate -p src/tsconfig.app.json
    

    Note: Once all of your dependencies have updated to RxJS 6, remove rxjs- compat as it increases bundle size. please see this RxJS Upgrade Guide for more info.

    npm uninstall rxjs-compat
    
  6. Done run ng serve to check it.
    If you get errors in build refer https://update.angular.io for detailed info.

Upgrade from Angular v5 to Angular 6.0.0-rc.5

  1. Upgrade rxjs to 6.0.0-beta.0, please see this RxJS Upgrade Guide for more info. RxJS v6 has breaking change hence first make your code compatible to latest RxJS version.

  2. Update NodeJS version to 8.9+ (this is required by angular cli 6 version)

  3. Update Angular cli global package to next version.

    npm uninstall -g @angular/cli
    npm cache verify
    

    if npm version is < 5 then use npm cache clean

    npm install -g @angular/cli@next
    
  4. Change angular packages versions in package.json file to ^6.0.0-rc.5

    "dependencies": {
      "@angular/animations": "^6.0.0-rc.5",
      "@angular/cdk": "^6.0.0-rc.12",
      "@angular/common": "^6.0.0-rc.5",
      "@angular/compiler": "^6.0.0-rc.5",
      "@angular/core": "^6.0.0-rc.5",
      "@angular/forms": "^6.0.0-rc.5",
      "@angular/http": "^6.0.0-rc.5",
      "@angular/material": "^6.0.0-rc.12",
      "@angular/platform-browser": "^6.0.0-rc.5",
      "@angular/platform-browser-dynamic": "^6.0.0-rc.5",
      "@angular/router": "^6.0.0-rc.5",
      "core-js": "^2.5.5",
      "karma-jasmine": "^1.1.1",
      "rxjs": "^6.0.0-uncanny-rc.7",
      "rxjs-compat": "^6.0.0-uncanny-rc.7",
      "zone.js": "^0.8.26"
    },
    "devDependencies": {
      "@angular-devkit/build-angular": "~0.5.0",
      "@angular/cli": "^6.0.0-rc.5",
      "@angular/compiler-cli": "^6.0.0-rc.5",
      "@types/jasmine": "2.5.38",
      "@types/node": "~8.9.4",
      "codelyzer": "~4.1.0",
      "jasmine-core": "~2.5.2",
      "jasmine-spec-reporter": "~3.2.0",
      "karma": "~1.4.1",
      "karma-chrome-launcher": "~2.0.0",
      "karma-cli": "~1.0.1",
      "karma-coverage-istanbul-reporter": "^0.2.0",
      "karma-jasmine": "~1.1.0",
      "karma-jasmine-html-reporter": "^0.2.2",
      "postcss-loader": "^2.1.4",
      "protractor": "~5.1.0",
      "ts-node": "~5.0.0",
      "tslint": "~5.9.1",
      "typescript": "^2.7.2"
    }
    
  5. Next update Angular cli local package to next version and install above mentioned packages.

    rm -rf node_modules dist # use rmdir /S/Q node_modules dist in Windows 
    Command Prompt; use rm -r -fo node_modules,dist in Windows PowerShell
    npm install --save-dev @angular/cli@next
    npm install 
    
  6. The Angular CLI configuration format has been changed from angular cli 6.0.0-rc.2 version, and your existing configuration can be updated automatically by running the following command. It will remove old config file .angular-cli.json and will write new angular.json file.

    ng update @angular/cli --migrate-only --from=1.7.4

Note :- If you get following error "The Angular Compiler requires TypeScript >=2.7.2 and <2.8.0 but 2.8.3 was found instead". run following command :

npm install [email protected]

Git log to get commits only for a specific branch

Here I present an alias based on Richard Hansen's answer (and Ben C's suggestion), but that I adapted to exclude tags. The alias should be fairly robust.

# For Git 1.22+
git config --global alias.only '!b=${1:-$(git branch --show-current)}; git log --oneline --graph "heads/$b" --not --exclude="$b" --branches --remotes #'
# For older Git:
git config --global alias.only '!b=${1:-$(git symbolic-ref -q --short HEAD)}; b=${b##heads/}; git log --oneline --graph "heads/$b" --not --exclude="$b" --branches --remotes #'

Example of use:

git only mybranch  # Show commits that are in mybranch ONLY
git only           # Show commits that are ONLY in current branch

Note that ONLY means commits that would be LOST (after garbage collection) if the given branch was deleted (excluding the effect of tags). The alias should work even if there is unfortunately a tag named mybranch (thanks to prefix heads/). Note also that no commits are shown if they are part of any remote branch (including upstream if any), in compliance with the definition of ONLY.

The alias shows the one-line history as a graph of the selected commits.

  a --- b --- c --- master
   \           \
    \           d
     \           \
      e --- f --- g --- mybranch (HEAD)
       \
        h --- origin/other

With example above, git only would show:

  * (mybranch,HEAD)
  * g
  |\
  | * d
  * f 

In order to include tags (but still excluding HEAD), the alias becomes (adapt as above for older Git):

git config --global alias.only '!b=${1:-$(git branch --show-current)};  git log --oneline --graph --all --not --exclude="refs/heads/$b" --exclude=HEAD --all #'

Or the variant that includes all the tags including HEAD (and removing current branch as default since it won't output anything):

git config --global alias.only '!git log --oneline --graph --all --not --exclude=\"refs/heads/$1\" --all #'

This last version is the only one that really satisfies the criteria commits-that-are-lost-if-given-branch-is-deleted, since a branch cannot be deleted if it is checked out, and no commit pointed by HEAD or any other tag will be lost. However the first two variants are more useful.

Finally, the alias does not work with remote branches (eg. git only origin/master). The alias must be modified, for instance:

git config --global alias.remote-only '!git log --oneline --graph "$1" --not --exclude="$1" --remotes --branches #'

Multiple IF AND statements excel

With your ANDs you shouldn't have a FALSE value -2, until right at the end, e.g. with just 2 ANDs

=IF(AND(E2="In Play",F2="Closed"),3,IF(AND(E2="In Play",F2=" Suspended"),3,-2))

although it might be better with a combination of nested IFs and ANDs - try like this for the full formula:[Edited - thanks David]

=IF(E2="In Play",IF(F2="Closed",3,IF(F2="Suspended",2,IF(F2="Null",1))),IF(AND(E2="Pre-play",F2="Null"),-1,IF(AND(E2="Completed",F2="Closed"),2,IF(AND(E2="Pre-play",F2="Null"),3,-2))))

To avoid a long formula like the above you could create a table with all E2 possibilities in a column like K2:K5 and all F2 possibilities in a row like L1:N1 then fill in the required results in L2:N5 and use this formula

=INDEX($L$2:$N$5,MATCH(E2,$K$2:$K$5,0),MATCH(F2,$L$1:$N$1,0))

Change font size of UISegmentedControl

C# / Xamarin:

segment.SetTitleTextAttributes(new UITextAttributes { 
    Font = UIFont.SystemFontOfSize(font_size) }, UIControlState.Normal);

Hide Twitter Bootstrap nav collapse on click

Adding the data-toggle="collapse" data-target=".navbar-collapse.in" to the tag <a> worked for me.

<div>

        <button type="button" class="navbar-toggle"  data-toggle="collapse" data-target=".navbar-collapse">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
        </button>
    </div>
            <div class="navbar-collapse collapse">
            <ul class="nav navbar-nav navbar-right">
                <li class="nav-item"><a
                    href="#" data-toggle="collapse" data-target=".navbar-collapse.in" class="nav-link" >Home
                </a></li>
            </ul>
    </div>

Invalid default value for 'dateAdded'

mysql version 5.5 set datetime default value as CURRENT_TIMESTAMP will be report error you can update to version 5.6 , it set datetime default value as CURRENT_TIMESTAMP

How to format font style and color in echo

 echo "<a href='#' style = \"font-color: #ff0000;\"> Movie List for {$key} 2013 </a>";

Using media breakpoints in Bootstrap 4-alpha

I answered a similar question here

As @Syden said, the mixins will work. Another option is using SASS map-get like this..

@media (min-width: map-get($grid-breakpoints, sm)){
  .something {
    padding: 10px;
   }
}

@media (min-width: map-get($grid-breakpoints, md)){
  .something {
    padding: 20px;
   }
}

http://www.codeply.com/go/0TU586QNlV


Bootstrap 4 Breakpoints demo

How can I rename a project folder from within Visual Studio?

I did the following:

<Create a backup of the entire folder>

  1. Rename the project from within Visual Studio 2013 (optional/not needed).

  2. Export the project as a template.

  3. Close the solution.

  4. Reopen the solution

  5. Create a project from the saved template and use the name you like.

  6. Delete from the solution explorer the previous project.

At this point I tried to compile the new solution, and to do so, I had to manually copy some resources and headers to the new project folder from the old project folder. Do this until it compiles without errors. Now this new project saved the ".exe" file to the previous folder.*

So ->

  1. Go to Windows Explorer and manually copy the solution file from the old project folder to the new project folder.

  2. Close the solution, and open the solution from within the new project.

  3. Changed the configuration back to (x64) if needed.

  4. Delete the folder of the project with the old name from the folder of the solution.

How to extend an existing JavaScript array with another array, without creating a new array

I like the a.push.apply(a, b) method described above, and if you want you can always create a library function like this:

Array.prototype.append = function(array)
{
    this.push.apply(this, array)
}

and use it like this

a = [1,2]
b = [3,4]

a.append(b)

What does "collect2: error: ld returned 1 exit status" mean?

Try running task manager to determine if your program is still running.

If it is running then stop it and run it again. the [Error] ld returned 1 exit status will not come back

How can I remove all my changes in my SVN working directory?

svn revert -R .
svn up

This will recursively revert the current directory and everything under it and then update to the latest version.

Smooth GPS data

Going back to the Kalman Filters ... I found a C implementation for a Kalman filter for GPS data here: http://github.com/lacker/ikalman I haven't tried it out yet, but it seems promising.

PHP Connection failed: SQLSTATE[HY000] [2002] Connection refused

In my case MySQL sever was not running. I restarted the MySQL server and issue was resolved.

//on ubuntu server
sudo /etc/init.d/mysql start

To avoid MySQL stop problem, you can use the "initctl" utility in Ubuntu 14.04 LTS Linux to make sure the service restarts in case of a failure or reboot. Please consider talking a snapshot of root volume (with mysql stopped) before performing this operations for data retention purpose[8]. You can use the following commands to manage the mysql service with "initctl" utility with stop and start operations.

$ sudo initctl stop mysql
$ sudo initctl start mysql

To verify the working, you can check the status of the service and get the process id (pid), simulate a failure by killing the "mysql" process and verify its status as running with new process id after sometime (typically within 1 minute) using the following commands.

$ sudo initctl status mysql         # get pid
$ sudo kill -9 <pid>                # kill mysql process
$ sudo initctl status mysql         # verify status as running after sometime

Note : In latest Ubuntu version now initctl is replaced by systemctl

Changing the color of an hr element

hr {
  height:0; 
  border:0; 
  border-top:1px solid #083972; 
}

This will keep the Horizontal Rule 1px thick while also changing the color of it

How is the java memory pool divided?

With Java8, non heap region no more contains PermGen but Metaspace, which is a major change in Java8, supposed to get rid of out of memory errors with java as metaspace size can be increased depending on the space required by jvm for class data.

How to remove the default arrow icon from a dropdown list (select element)?

there's a library called DropKick.js that replaces the normal select dropdowns with HTML/CSS so you can fully style and control them with javascript. http://dropkickjs.com/

How do I use two submit buttons, and differentiate between which one was used to submit the form?

Give name and values to those submit buttons like:

    <td>
    <input type="submit" name='mybutton' class="noborder" id="save" value="save" alt="Save" tabindex="4" />
    </td>
    <td>
    <input type="submit" name='mybutton' class="noborder" id="publish" value="publish" alt="Publish" tabindex="5" />
    </td>

and then in your php script you could check

if($_POST['mybutton'] == 'save')
{
  ///do save processing
}
elseif($_POST['mybutton'] == 'publish')
{
  ///do publish processing here
}

How to capture multiple repeated groups?

With one group in the pattern, you can only get one exact result in that group. If your capture group gets repeated by the pattern (you used the + quantifier on the surrounding non-capturing group), only the last value that matches it gets stored.

You have to use your language's regex implementation functions to find all matches of a pattern, then you would have to remove the anchors and the quantifier of the non-capturing group (and you could omit the non-capturing group itself as well).

Alternatively, expand your regex and let the pattern contain one capturing group per group you want to get in the result:

^([A-Z]+),([A-Z]+),([A-Z]+)$

How do you use bcrypt for hashing passwords in PHP?

The password_hash() function in PHP is an inbuilt function , used to create a new password hash with different algorithms and options. the function uses a strong hashing algorithm.

the function take 2 mandetory parametres ($password and $algorithm,) and 1 optional parameter ($options).

$strongPassword = password_hash( $password, $algorithm, $options )


Algoristrong textthms allowed right now for password_hash() are :

  • PASSWORD_DEFAULT

  • PASSWORD_BCRYPT

  • ASSWORD_ARGON2I

  • PASSWORD_ARGON2ID


example : echo password_hash("abcDEF", PASSWORD_DEFAULT);

answer : $2y$10$KwKceUaG84WInAif5ehdZOkE4kHPWTLp0ZK5a5OU2EbtdwQ9YIcGy


example: `echo password_hash("abcDEF", PASSWORD_BCRYPT);`

answer :$2y$10$SNly5bFzB/R6OVbBMq1bj.yiOZdsk6Mwgqi4BLR2sqdCvMyv/AyL2


to use the BCRYPT as password, use option cost =12 in an array , also change 1st parameter $password to some strong password like "wgt167yuWBGY@#1987__"

Example: echo password_hash("wgt167yuWBGY@#1987__", PASSWORD_BCRYPT ,['cost' => 12]);

Answer : $2y$12$TjSggXiFSidD63E.QP8PJOds2texJfsk/82VaNU8XRZ/niZhzkJ6S

How to analyze a JMeter summary report?

Sample: Number of requests sent.

The Throughput: is the number of requests per unit of time (seconds, minutes, hours) that are sent to your server during the test.

The Response time: is the elapsed time from the moment when a given request is sent to the server until the moment when the last bit of information has returned to the client.

The throughput is the real load processed by your server during a run but it does not tell you anything about the performance of your server during this same run. This is the reason why you need both measures in order to get a real idea about your server’s performance during a run. The response time tells you how fast your server is handling a given load.

Average: This is the Average (Arithmetic mean µ = 1/n * Si=1…n xi) Response time of your total samples.

Min and Max are the minimum and maximum response time.

An important thing to understand is that the mean value can be very misleading as it does not show you how close (or far) your values are from the average.For this purpose, we need the Deviation value since Average value can be the Same for different response time of the samples!!

Deviation: The standard deviation (s) measures the mean distance of the values to their average (µ).It gives you a good idea of the dispersion or variability of the measures to their mean value.

The following equation show how the standard deviation (s) is calculated:

s = 1/n * v Si=1…n (xi-µ)2

For Details, see here!!

So, if the deviation value is low compared to the mean value, it will indicate you that your measures are not dispersed (or mostly close to the mean value) and that the mean value is significant.

Kb/sec: The throughput measured in Kilobytes per second.

Error % : Percent of requests with errors.

An example is always better to understand!!! I think, this article will help you.

Sonar properties files

You can define a Multi-module project structure, then you can set the configuration for sonar in one properties file in the root folder of your project, (Way #1)

How can I scale an image in a CSS sprite

Use transform: scale(...); and add matching margin: -...px to compensate free space from scaling. (you can use * {outline: 1px solid}to see element boundaries).

Show two digits after decimal point in c++

Using header file stdio.h you can easily do it as usual like c. before using %.2lf(set a specific number after % specifier.) using printf().

It simply printf specific digits after decimal point.

#include <stdio.h>
#include <iostream>
using namespace std;
int main()
{
   double total=100;
   printf("%.2lf",total);//this prints 100.00 like as C
}

Matplotlib connect scatterplot points with line - Python

I think @Evert has the right answer:

plt.scatter(dates,values)
plt.plot(dates, values)
plt.show()

Which is pretty much the same as

plt.plot(dates, values, '-o')
plt.show()

or whatever linestyle you prefer.

Select the values of one property on all objects of an array in PowerShell

As an even easier solution, you could just use:

$results = $objects.Name

Which should fill $results with an array of all the 'Name' property values of the elements in $objects.

calling java methods in javascript code

When it is on server side, use web services - maybe RESTful with JSON.

  • create a web service (for example with Tomcat)
  • call its URL from JavaScript (for example with JQuery or dojo)

When Java code is in applet you can use JavaScript bridge. The bridge between the Java and JavaScript programming languages, known informally as LiveConnect, is implemented in Java plugin. Formerly Mozilla-specific LiveConnect functionality, such as the ability to call static Java methods, instantiate new Java objects and reference third-party packages from JavaScript, is now available in all browsers.

Below is example from documentation. Look at methodReturningString.

Java code:

public class MethodInvocation extends Applet {
    public void noArgMethod() { ... }
    public void someMethod(String arg) { ... }
    public void someMethod(int arg) { ... }
    public int  methodReturningInt() { return 5; }
    public String methodReturningString() { return "Hello"; }
    public OtherClass methodReturningObject() { return new OtherClass(); }
}

public class OtherClass {
    public void anotherMethod();
}

Web page and JavaScript code:

<applet id="app"
        archive="examples.jar"
        code="MethodInvocation" ...>
</applet>
<script language="javascript">
    app.noArgMethod();
    app.someMethod("Hello");
    app.someMethod(5);
    var five = app.methodReturningInt();
    var hello = app.methodReturningString();
    app.methodReturningObject().anotherMethod();
</script>

BASH Syntax error near unexpected token 'done'

Might help someone else : I encountered the same kind of issues while I had done some "copy-paste" from a side Microsoft Word document, where I took notes, to my shell script(s).

Re-writing, manually, the exact same code in the script just solved this.

It was quite un-understandable at first, I think Word's hidden characters and/or formatting were the issue. Obvious but not see-able ... I lost about one hour on this (I'm no shell expert, as you might guess ...)

JWT refresh token flow

Assuming that this is about OAuth 2.0 since it is about JWTs and refresh tokens...:

  1. just like an access token, in principle a refresh token can be anything including all of the options you describe; a JWT could be used when the Authorization Server wants to be stateless or wants to enforce some sort of "proof-of-possession" semantics on to the client presenting it; note that a refresh token differs from an access token in that it is not presented to a Resource Server but only to the Authorization Server that issued it in the first place, so the self-contained validation optimization for JWTs-as-access-tokens does not hold for refresh tokens

  2. that depends on the security/access of the database; if the database can be accessed by other parties/servers/applications/users, then yes (but your mileage may vary with where and how you store the encryption key...)

  3. an Authorization Server may issue both access tokens and refresh tokens at the same time, depending on the grant that is used by the client to obtain them; the spec contains the details and options on each of the standardized grants

Clone() vs Copy constructor- which is recommended in java

Clone is broken, so dont use it.

THE CLONE METHOD of the Object class is a somewhat magical method that does what no pure Java method could ever do: It produces an identical copy of its object. It has been present in the primordial Object superclass since the Beta-release days of the Java compiler*; and it, like all ancient magic, requires the appropriate incantation to prevent the spell from unexpectedly backfiring

Prefer a method that copies the object

Foo copyFoo (Foo foo){
  Foo f = new Foo();
  //for all properties in FOo
  f.set(foo.get());
  return f;
}

Read more http://adtmag.com/articles/2000/01/18/effective-javaeffective-cloning.aspx

Free ASP.Net and/or CSS Themes

Microsoft hired one fo the kids from A List Apart to whip some out. The .Net projects are free of charge for download.

http://msdn.microsoft.com/en-us/asp.net/aa336613.aspx

EXC_BAD_ACCESS signal received

I encountered EXC_BAD_ACCESS on the iPhone only while trying to execute a C method that included a big array. The simulator was able to give me enough memory to run the code, but not the device (the array was a million characters, so it was a tad excessive!).

The EXC_BAD_ACCESS occurred just after entry point of the method, and had me confused for quite a while because it was nowhere near the array declaration.

Perhaps someone else might benefit from my couple of hours of hair-pulling.

Understanding typedefs for function pointers in C

int add(int a, int b)
{
  return (a+b);
}
int minus(int a, int b)
{
  return (a-b);
}

typedef int (*math_func)(int, int); //declaration of function pointer

int main()
{
  math_func addition = add;  //typedef assigns a new variable i.e. "addition" to original function "add"
  math_func substract = minus; //typedef assigns a new variable i.e. "substract" to original function "minus"

  int c = addition(11, 11);   //calling function via new variable
  printf("%d\n",c);
  c = substract(11, 5);   //calling function via new variable
  printf("%d",c);
  return 0;
}

Output of this is :

22

6

Note that, same math_func definer has been used for the declaring both the function.

Same approach of typedef may be used for extern struct.(using sturuct in other file.)

Bash tool to get nth line from a file

All the above answers directly answer the question. But here's a less direct solution but a potentially more important idea, to provoke thought.

Since line lengths are arbitrary, all the bytes of the file before the nth line need to be read. If you have a huge file or need to repeat this task many times, and this process is time-consuming, then you should seriously think about whether you should be storing your data in a different way in the first place.

The real solution is to have an index, e.g. at the start of the file, indicating the positions where the lines begin. You could use a database format, or just add a table at the start of the file. Alternatively create a separate index file to accompany your large text file.

e.g. you might create a list of character positions for newlines:

awk 'BEGIN{c=0;print(c)}{c+=length()+1;print(c+1)}' file.txt > file.idx

then read with tail, which actually seeks directly to the appropriate point in the file!

e.g. to get line 1000:

tail -c +$(awk 'NR=1000' file.idx) file.txt | head -1
  • This may not work with 2-byte / multibyte characters, since awk is "character-aware" but tail is not.
  • I haven't tested this against a large file.
  • Also see this answer.
  • Alternatively - split your file into smaller files!

Passing an array of parameters to a stored procedure

I'd consider passing your IDs as an XML string, and then you could shred the XML into a temp table to join against, or you could also query against the XML directly using SP_XML_PREPAREDOCUMENT and OPENXML.

How do I create executable Java program?

If you are using NetBeans, you just press f11 and your project will be build. The default path is projectfolder\dist

What arguments are passed into AsyncTask<arg1, arg2, arg3>?

  • in Short, There are 3 parameters in AsyncTask

    1. parameters for Input use in DoInBackground(String... params)

    2. parameters for show status of progress use in OnProgressUpdate(String... status)

    3. parameters for result use in OnPostExcute(String... result)

    Note : - [Type of parameters can vary depending on your requirement]

Weblogic Transaction Timeout : how to set in admin console in WebLogic AS 8.1

After logging in, on the home page of the Server Console you should see 3 sections:

  • Information and Resources
  • Domain Configurations
  • Services Configurations

Under Services Configurations there is subsection Other Services. Click the JTA Configuration link under Other Services. The transaction timeout should be the top setting on the page displayed, labelled Timeout Seconds.

Weblogic Console screenshot

In Visual Basic how do you create a block comment

Not in VB.NET, you have to select all lines at then Edit, Advanced, Comment Selection menu, or a keyboard shortcut for that menu.

http://bytes.com/topic/visual-basic-net/answers/376760-how-block-comment

http://forums.asp.net/t/1011404.aspx/1

How to generate a GUID in Oracle?

Example found on: http://www.orafaq.com/usenet/comp.databases.oracle.server/2006/12/20/0646.htm

SELECT REGEXP_REPLACE(SYS_GUID(), '(.{8})(.{4})(.{4})(.{4})(.{12})', '\1-\2-\3-\4-\5') MSSQL_GUID  FROM DUAL 

Result:

6C7C9A50-3514-4E77-E053-B30210AC1082 

How is "mvn clean install" different from "mvn install"?

To stick with the Maven terms:

  • "clean" is a phase of the clean lifecycle
  • "install" is a phase of the default lifecycle

http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html#Lifecycle_Reference

How to convert a Java 8 Stream to an Array?

If you want to get an array of ints, with values from 1 to 10, from a Stream<Integer>, there is IntStream at your disposal.

Here we create a Stream with a Stream.of method and convert a Stream<Integer> to an IntStream using a mapToInt. Then we can call IntStream's toArray method.

Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9,10);
//or use this to create our stream 
//Stream<Integer> stream = IntStream.rangeClosed(1, 10).boxed();
int[] array =  stream.mapToInt(x -> x).toArray();

Here is the same thing, without the Stream<Integer>, using only the IntStream:

int[]array2 =  IntStream.rangeClosed(1, 10).toArray();

Can we call the function written in one JavaScript in another JS file?

You can call the function created in another js file from the file you are working in. So for this firstly you need to add the external js file into the html document as-

<html>
<head>
    <script type="text/javascript" src='path/to/external/js'></script>
</head>
<body>
........

The function defined in the external javascript file -

$.fn.yourFunctionName = function(){
    alert('function called succesfully for - ' + $(this).html() );
}

To call this function in your current file, just call the function as -

......
<script type="text/javascript">
    $(function(){
        $('#element').yourFunctionName();
    });
</script>

If you want to pass the parameters to the function, then define the function as-

$.fn.functionWithParameters = function(parameter1, parameter2){
        alert('Parameters passed are - ' + parameter1 + ' , ' + parameter2);
}

And call this function in your current file as -

$('#element').functionWithParameters('some parameter', 'another parameter');

Zip folder in C#

There's an article over on MSDN that has a sample application for zipping and unzipping files and folders purely in C#. I've been using some of the classes in that successfully for a long time. The code is released under the Microsoft Permissive License, if you need to know that sort of thing.

EDIT: Thanks to Cheeso for pointing out that I'm a bit behind the times. The MSDN example I pointed to is in fact using DotNetZip and is really very fully-featured these days. Based on my experience of a previous version of this I'd happily recommend it.

SharpZipLib is also quite a mature library and is highly rated by people, and is available under the GPL license. It really depends on your zipping needs and how you view the license terms for each of them.

Rich

Java constant examples (Create a java file having only constants)

- Create a Class with public static final fields.

- And then you can access these fields from any class using the Class_Name.Field_Name.

- You can declare the class as final, so that the class can't be extended(Inherited) and modify....

applying css to specific li class

You are defining the color: #C1C1C1; for all the a elements with #sub-nav-container a.

Doing it again in li.sub-navigation-home-news won't do anything, as it is a parent of the a element.

Add directives from directive in AngularJS

There was a change from 1.3.x to 1.4.x.

In Angular 1.3.x this worked:

var dir: ng.IDirective = {
    restrict: "A",
    require: ["select", "ngModel"],
    compile: compile,
};

function compile(tElement: ng.IAugmentedJQuery, tAttrs, transclude) {
    tElement.append("<option value=''>--- Kein ---</option>");

    return function postLink(scope: DirectiveScope, element: ng.IAugmentedJQuery, attributes: ng.IAttributes) {
        attributes["ngOptions"] = "a.ID as a.Bezeichnung for a in akademischetitel";
        scope.akademischetitel = AkademischerTitel.query();
    }
}

Now in Angular 1.4.x we have to do this:

var dir: ng.IDirective = {
    restrict: "A",
    compile: compile,
    terminal: true,
    priority: 10,
};

function compile(tElement: ng.IAugmentedJQuery, tAttrs, transclude) {
    tElement.append("<option value=''>--- Kein ---</option>");
    tElement.removeAttr("tq-akademischer-titel-select");
    tElement.attr("ng-options", "a.ID as a.Bezeichnung for a in akademischetitel");

    return function postLink(scope: DirectiveScope, element: ng.IAugmentedJQuery, attributes: ng.IAttributes) {

        $compile(element)(scope);
        scope.akademischetitel = AkademischerTitel.query();
    }
}

(From the accepted answer: https://stackoverflow.com/a/19228302/605586 from Khanh TO).

SQLite select where empty?

There are several ways, like:

where some_column is null or some_column = ''

or

where ifnull(some_column, '') = ''

or

where coalesce(some_column, '') = ''

of

where ifnull(length(some_column), 0) = 0

exception in thread 'main' java.lang.NoClassDefFoundError:

Add the jar in your classpath.

For example, if you have NoClassDefFoundError for class XXXXXX, get the jar containing the class and add it to your classpath manually.

It works for me. Hopefully it will work for you as well.

Groovy - Convert object to JSON string

You can use JsonBuilder for that.

Example Code:

import groovy.json.JsonBuilder

class Person {
    String name
    String address
}

def o = new Person( name: 'John Doe', address: 'Texas' )

println new JsonBuilder( o ).toPrettyString()

jQuery select change event get selected option

Another and short way to get value of selected value,

$('#selectElement').on('change',function(){
   var selectedVal = $(this).val();
                       ^^^^  ^^^^ -> presents #selectElement selected value 
                         |
                         v
               presents #selectElement, 
});

Import Script from a Parent Directory

If you want to run the script directly, you can:

  1. Add the FolderA's path to the environment variable (PYTHONPATH).
  2. Add the path to sys.path in the your script.

Then:

import module_you_wanted

Sum values in foreach loop php

$sum = 0;
foreach($group as $key=>$value)
{
   $sum+= $value;
}
echo $sum;

Java ArrayList of Doubles

Try this:

List<Double> list = Arrays.asList(1.38, 2.56, 4.3);

which returns a fixed size list.

If you need an expandable list, pass this result to the ArrayList constructor:

List<Double> list = new ArrayList<>(Arrays.asList(1.38, 2.56, 4.3));

data.table vs dplyr: can one do something well the other can't or does poorly?

We need to cover at least these aspects to provide a comprehensive answer/comparison (in no particular order of importance): Speed, Memory usage, Syntax and Features.

My intent is to cover each one of these as clearly as possible from data.table perspective.

Note: unless explicitly mentioned otherwise, by referring to dplyr, we refer to dplyr's data.frame interface whose internals are in C++ using Rcpp.


The data.table syntax is consistent in its form - DT[i, j, by]. To keep i, j and by together is by design. By keeping related operations together, it allows to easily optimise operations for speed and more importantly memory usage, and also provide some powerful features, all while maintaining the consistency in syntax.

1. Speed

Quite a few benchmarks (though mostly on grouping operations) have been added to the question already showing data.table gets faster than dplyr as the number of groups and/or rows to group by increase, including benchmarks by Matt on grouping from 10 million to 2 billion rows (100GB in RAM) on 100 - 10 million groups and varying grouping columns, which also compares pandas. See also updated benchmarks, which include Spark and pydatatable as well.

On benchmarks, it would be great to cover these remaining aspects as well:

  • Grouping operations involving a subset of rows - i.e., DT[x > val, sum(y), by = z] type operations.

  • Benchmark other operations such as update and joins.

  • Also benchmark memory footprint for each operation in addition to runtime.

2. Memory usage

  1. Operations involving filter() or slice() in dplyr can be memory inefficient (on both data.frames and data.tables). See this post.

    Note that Hadley's comment talks about speed (that dplyr is plentiful fast for him), whereas the major concern here is memory.

  2. data.table interface at the moment allows one to modify/update columns by reference (note that we don't need to re-assign the result back to a variable).

    # sub-assign by reference, updates 'y' in-place
    DT[x >= 1L, y := NA]
    

    But dplyr will never update by reference. The dplyr equivalent would be (note that the result needs to be re-assigned):

    # copies the entire 'y' column
    ans <- DF %>% mutate(y = replace(y, which(x >= 1L), NA))
    

    A concern for this is referential transparency. Updating a data.table object by reference, especially within a function may not be always desirable. But this is an incredibly useful feature: see this and this posts for interesting cases. And we want to keep it.

    Therefore we are working towards exporting shallow() function in data.table that will provide the user with both possibilities. For example, if it is desirable to not modify the input data.table within a function, one can then do:

    foo <- function(DT) {
        DT = shallow(DT)          ## shallow copy DT
        DT[, newcol := 1L]        ## does not affect the original DT 
        DT[x > 2L, newcol := 2L]  ## no need to copy (internally), as this column exists only in shallow copied DT
        DT[x > 2L, x := 3L]       ## have to copy (like base R / dplyr does always); otherwise original DT will 
                                  ## also get modified.
    }
    

    By not using shallow(), the old functionality is retained:

    bar <- function(DT) {
        DT[, newcol := 1L]        ## old behaviour, original DT gets updated by reference
        DT[x > 2L, x := 3L]       ## old behaviour, update column x in original DT.
    }
    

    By creating a shallow copy using shallow(), we understand that you don't want to modify the original object. We take care of everything internally to ensure that while also ensuring to copy columns you modify only when it is absolutely necessary. When implemented, this should settle the referential transparency issue altogether while providing the user with both possibilties.

    Also, once shallow() is exported dplyr's data.table interface should avoid almost all copies. So those who prefer dplyr's syntax can use it with data.tables.

    But it will still lack many features that data.table provides, including (sub)-assignment by reference.

  3. Aggregate while joining:

    Suppose you have two data.tables as follows:

    DT1 = data.table(x=c(1,1,1,1,2,2,2,2), y=c("a", "a", "b", "b"), z=1:8, key=c("x", "y"))
    #    x y z
    # 1: 1 a 1
    # 2: 1 a 2
    # 3: 1 b 3
    # 4: 1 b 4
    # 5: 2 a 5
    # 6: 2 a 6
    # 7: 2 b 7
    # 8: 2 b 8
    DT2 = data.table(x=1:2, y=c("a", "b"), mul=4:3, key=c("x", "y"))
    #    x y mul
    # 1: 1 a   4
    # 2: 2 b   3
    

    And you would like to get sum(z) * mul for each row in DT2 while joining by columns x,y. We can either:

    • 1) aggregate DT1 to get sum(z), 2) perform a join and 3) multiply (or)

      # data.table way
      DT1[, .(z = sum(z)), keyby = .(x,y)][DT2][, z := z*mul][]
      
      # dplyr equivalent
      DF1 %>% group_by(x, y) %>% summarise(z = sum(z)) %>% 
          right_join(DF2) %>% mutate(z = z * mul)
      
    • 2) do it all in one go (using by = .EACHI feature):

      DT1[DT2, list(z=sum(z) * mul), by = .EACHI]
      

    What is the advantage?

    • We don't have to allocate memory for the intermediate result.

    • We don't have to group/hash twice (one for aggregation and other for joining).

    • And more importantly, the operation what we wanted to perform is clear by looking at j in (2).

    Check this post for a detailed explanation of by = .EACHI. No intermediate results are materialised, and the join+aggregate is performed all in one go.

    Have a look at this, this and this posts for real usage scenarios.

    In dplyr you would have to join and aggregate or aggregate first and then join, neither of which are as efficient, in terms of memory (which in turn translates to speed).

  4. Update and joins:

    Consider the data.table code shown below:

    DT1[DT2, col := i.mul]
    

    adds/updates DT1's column col with mul from DT2 on those rows where DT2's key column matches DT1. I don't think there is an exact equivalent of this operation in dplyr, i.e., without avoiding a *_join operation, which would have to copy the entire DT1 just to add a new column to it, which is unnecessary.

    Check this post for a real usage scenario.

To summarise, it is important to realise that every bit of optimisation matters. As Grace Hopper would say, Mind your nanoseconds!

3. Syntax

Let's now look at syntax. Hadley commented here:

Data tables are extremely fast but I think their concision makes it harder to learn and code that uses it is harder to read after you have written it ...

I find this remark pointless because it is very subjective. What we can perhaps try is to contrast consistency in syntax. We will compare data.table and dplyr syntax side-by-side.

We will work with the dummy data shown below:

DT = data.table(x=1:10, y=11:20, z=rep(1:2, each=5))
DF = as.data.frame(DT)
  1. Basic aggregation/update operations.

    # case (a)
    DT[, sum(y), by = z]                       ## data.table syntax
    DF %>% group_by(z) %>% summarise(sum(y)) ## dplyr syntax
    DT[, y := cumsum(y), by = z]
    ans <- DF %>% group_by(z) %>% mutate(y = cumsum(y))
    
    # case (b)
    DT[x > 2, sum(y), by = z]
    DF %>% filter(x>2) %>% group_by(z) %>% summarise(sum(y))
    DT[x > 2, y := cumsum(y), by = z]
    ans <- DF %>% group_by(z) %>% mutate(y = replace(y, which(x > 2), cumsum(y)))
    
    # case (c)
    DT[, if(any(x > 5L)) y[1L]-y[2L] else y[2L], by = z]
    DF %>% group_by(z) %>% summarise(if (any(x > 5L)) y[1L] - y[2L] else y[2L])
    DT[, if(any(x > 5L)) y[1L] - y[2L], by = z]
    DF %>% group_by(z) %>% filter(any(x > 5L)) %>% summarise(y[1L] - y[2L])
    
    • data.table syntax is compact and dplyr's quite verbose. Things are more or less equivalent in case (a).

    • In case (b), we had to use filter() in dplyr while summarising. But while updating, we had to move the logic inside mutate(). In data.table however, we express both operations with the same logic - operate on rows where x > 2, but in first case, get sum(y), whereas in the second case update those rows for y with its cumulative sum.

      This is what we mean when we say the DT[i, j, by] form is consistent.

    • Similarly in case (c), when we have if-else condition, we are able to express the logic "as-is" in both data.table and dplyr. However, if we would like to return just those rows where the if condition satisfies and skip otherwise, we cannot use summarise() directly (AFAICT). We have to filter() first and then summarise because summarise() always expects a single value.

      While it returns the same result, using filter() here makes the actual operation less obvious.

      It might very well be possible to use filter() in the first case as well (does not seem obvious to me), but my point is that we should not have to.

  2. Aggregation / update on multiple columns

    # case (a)
    DT[, lapply(.SD, sum), by = z]                     ## data.table syntax
    DF %>% group_by(z) %>% summarise_each(funs(sum)) ## dplyr syntax
    DT[, (cols) := lapply(.SD, sum), by = z]
    ans <- DF %>% group_by(z) %>% mutate_each(funs(sum))
    
    # case (b)
    DT[, c(lapply(.SD, sum), lapply(.SD, mean)), by = z]
    DF %>% group_by(z) %>% summarise_each(funs(sum, mean))
    
    # case (c)
    DT[, c(.N, lapply(.SD, sum)), by = z]     
    DF %>% group_by(z) %>% summarise_each(funs(n(), mean))
    
    • In case (a), the codes are more or less equivalent. data.table uses familiar base function lapply(), whereas dplyr introduces *_each() along with a bunch of functions to funs().

    • data.table's := requires column names to be provided, whereas dplyr generates it automatically.

    • In case (b), dplyr's syntax is relatively straightforward. Improving aggregations/updates on multiple functions is on data.table's list.

    • In case (c) though, dplyr would return n() as many times as many columns, instead of just once. In data.table, all we need to do is to return a list in j. Each element of the list will become a column in the result. So, we can use, once again, the familiar base function c() to concatenate .N to a list which returns a list.

    Note: Once again, in data.table, all we need to do is return a list in j. Each element of the list will become a column in result. You can use c(), as.list(), lapply(), list() etc... base functions to accomplish this, without having to learn any new functions.

    You will need to learn just the special variables - .N and .SD at least. The equivalent in dplyr are n() and .

  3. Joins

    dplyr provides separate functions for each type of join where as data.table allows joins using the same syntax DT[i, j, by] (and with reason). It also provides an equivalent merge.data.table() function as an alternative.

    setkey(DT1, x, y)
    
    # 1. normal join
    DT1[DT2]            ## data.table syntax
    left_join(DT2, DT1) ## dplyr syntax
    
    # 2. select columns while join    
    DT1[DT2, .(z, i.mul)]
    left_join(select(DT2, x, y, mul), select(DT1, x, y, z))
    
    # 3. aggregate while join
    DT1[DT2, .(sum(z) * i.mul), by = .EACHI]
    DF1 %>% group_by(x, y) %>% summarise(z = sum(z)) %>% 
        inner_join(DF2) %>% mutate(z = z*mul) %>% select(-mul)
    
    # 4. update while join
    DT1[DT2, z := cumsum(z) * i.mul, by = .EACHI]
    ??
    
    # 5. rolling join
    DT1[DT2, roll = -Inf]
    ??
    
    # 6. other arguments to control output
    DT1[DT2, mult = "first"]
    ??
    
    • Some might find a separate function for each joins much nicer (left, right, inner, anti, semi etc), whereas as others might like data.table's DT[i, j, by], or merge() which is similar to base R.

    • However dplyr joins do just that. Nothing more. Nothing less.

    • data.tables can select columns while joining (2), and in dplyr you will need to select() first on both data.frames before to join as shown above. Otherwise you would materialiase the join with unnecessary columns only to remove them later and that is inefficient.

    • data.tables can aggregate while joining (3) and also update while joining (4), using by = .EACHI feature. Why materialse the entire join result to add/update just a few columns?

    • data.table is capable of rolling joins (5) - roll forward, LOCF, roll backward, NOCB, nearest.

    • data.table also has mult = argument which selects first, last or all matches (6).

    • data.table has allow.cartesian = TRUE argument to protect from accidental invalid joins.

Once again, the syntax is consistent with DT[i, j, by] with additional arguments allowing for controlling the output further.

  1. do()...

    dplyr's summarise is specially designed for functions that return a single value. If your function returns multiple/unequal values, you will have to resort to do(). You have to know beforehand about all your functions return value.

    DT[, list(x[1], y[1]), by = z]                 ## data.table syntax
    DF %>% group_by(z) %>% summarise(x[1], y[1]) ## dplyr syntax
    DT[, list(x[1:2], y[1]), by = z]
    DF %>% group_by(z) %>% do(data.frame(.$x[1:2], .$y[1]))
    
    DT[, quantile(x, 0.25), by = z]
    DF %>% group_by(z) %>% summarise(quantile(x, 0.25))
    DT[, quantile(x, c(0.25, 0.75)), by = z]
    DF %>% group_by(z) %>% do(data.frame(quantile(.$x, c(0.25, 0.75))))
    
    DT[, as.list(summary(x)), by = z]
    DF %>% group_by(z) %>% do(data.frame(as.list(summary(.$x))))
    
    • .SD's equivalent is .

    • In data.table, you can throw pretty much anything in j - the only thing to remember is for it to return a list so that each element of the list gets converted to a column.

    • In dplyr, cannot do that. Have to resort to do() depending on how sure you are as to whether your function would always return a single value. And it is quite slow.

Once again, data.table's syntax is consistent with DT[i, j, by]. We can just keep throwing expressions in j without having to worry about these things.

Have a look at this SO question and this one. I wonder if it would be possible to express the answer as straightforward using dplyr's syntax...

To summarise, I have particularly highlighted several instances where dplyr's syntax is either inefficient, limited or fails to make operations straightforward. This is particularly because data.table gets quite a bit of backlash about "harder to read/learn" syntax (like the one pasted/linked above). Most posts that cover dplyr talk about most straightforward operations. And that is great. But it is important to realise its syntax and feature limitations as well, and I am yet to see a post on it.

data.table has its quirks as well (some of which I have pointed out that we are attempting to fix). We are also attempting to improve data.table's joins as I have highlighted here.

But one should also consider the number of features that dplyr lacks in comparison to data.table.

4. Features

I have pointed out most of the features here and also in this post. In addition:

  • fread - fast file reader has been available for a long time now.

  • fwrite - a parallelised fast file writer is now available. See this post for a detailed explanation on the implementation and #1664 for keeping track of further developments.

  • Automatic indexing - another handy feature to optimise base R syntax as is, internally.

  • Ad-hoc grouping: dplyr automatically sorts the results by grouping variables during summarise(), which may not be always desirable.

  • Numerous advantages in data.table joins (for speed / memory efficiency and syntax) mentioned above.

  • Non-equi joins: Allows joins using other operators <=, <, >, >= along with all other advantages of data.table joins.

  • Overlapping range joins was implemented in data.table recently. Check this post for an overview with benchmarks.

  • setorder() function in data.table that allows really fast reordering of data.tables by reference.

  • dplyr provides interface to databases using the same syntax, which data.table does not at the moment.

  • data.table provides faster equivalents of set operations (written by Jan Gorecki) - fsetdiff, fintersect, funion and fsetequal with additional all argument (as in SQL).

  • data.table loads cleanly with no masking warnings and has a mechanism described here for [.data.frame compatibility when passed to any R package. dplyr changes base functions filter, lag and [ which can cause problems; e.g. here and here.


Finally:

  • On databases - there is no reason why data.table cannot provide similar interface, but this is not a priority now. It might get bumped up if users would very much like that feature.. not sure.

  • On parallelism - Everything is difficult, until someone goes ahead and does it. Of course it will take effort (being thread safe).

    • Progress is being made currently (in v1.9.7 devel) towards parallelising known time consuming parts for incremental performance gains using OpenMP.

Python: can't assign to literal

1 is a literal. name = value is an assignment. 1 = value is an assignment to a literal, which makes no sense. Why would you want 1 to mean something other than 1?

Automapper missing type map configuration or unsupported mapping - Error

In your class AutoMapper profile, you need to create a map for your entity and viewmodel.

ViewModel To Domain Model Mappings:

This is usually in AutoMapper/DomainToViewModelMappingProfile

In Configure(), add a line like

Mapper.CreateMap<YourEntityViewModel, YourEntity>();

Domain Model To ViewModel Mappings:

In ViewModelToDomainMappingProfile, add:

Mapper.CreateMap<YourEntity, YourEntityViewModel>();

Gist example

Connect different Windows User in SQL Server Management Studio (2005 or later)

None of these answers did what I needed: Login to a remote server using a different domain account than I was logged into on my local machine, and it's a client's domain across a vpn. I don't want to be on their domain!

Instead, on the connect to server dialog, select "Windows Authentication", click the Options button, and then on the Additional Connection Parameters tab, enter

user id=domain\user;password=password

SSMS won't remember, but it will connect with that account.

How do I convert an Array to a List<object> in C#?

If array item and list item are same

List<object> list=myArray.ToList();

What's the difference between SHA and AES encryption?

SHA doesn't require anything but an input to be applied, while AES requires at least 3 things - what you're encrypting/decrypting, an encryption key, and the initialization vector.

Weird behavior of the != XPath operator

If $AccountNumber or $Balance is a node-set, then this behavior could easily happen. It's not because and is being treated as or.

For example, if $AccountNumber referred to nodes with the values 12345 and 66 and $Balance referred to nodes with the values 55 and 0, then $AccountNumber != '12345' would be true (because 66 is not equal to 12345) and $Balance != '0' would be true (because 55 is not equal to 0).

I'd suggest trying this instead:

<xsl:when test="not($AccountNumber = '12345' or $Balance = '0')">

$AccountNumber = '12345' or $Balance = '0' will be true any time there is an $AccountNumber with the value 12345 or there is a $Balance with the value 0, and if you apply not() to that, you will get a false result.

Could not find tools.jar. Please check that C:\Program Files\Java\jre1.8.0_151 contains a valid JDK installation

At last, here I found the solution.

I added jdk path org.gradle.java.home=C:\\Program Files\\Java\\jdk1.8.0_144 to gradle.properties file and did a rebuild. It works now.

Insert current date in datetime format mySQL

"datetime" expects the date to be formated like this: YYYY-MM-DD HH:MM:SS

so format your date like that when you are inserting.

Assign output of os.system to a variable and prevent it from being displayed on the screen

Python 2.6 and 3 specifically say to avoid using PIPE for stdout and stderr.

The correct way is

import subprocess

# must create a file object to store the output. Here we are getting
# the ssid we are connected to
outfile = open('/tmp/ssid', 'w');
status = subprocess.Popen(["iwgetid"], bufsize=0, stdout=outfile)
outfile.close()

# now operate on the file

Sending SMS from PHP

Clickatell is a popular SMS gateway. It works in 200+ countries.

Their API offers a choice of connection options via: HTTP/S, SMPP, SMTP, FTP, XML, SOAP. Any of these options can be used from php.

The HTTP/S method is as simple as this:

http://api.clickatell.com/http/sendmsg?to=NUMBER&msg=Message+Body+Here

The SMTP method consists of sending a plain-text e-mail to: [email protected], with the following body:

user: xxxxx
password: xxxxx
api_id: xxxxx
to: 448311234567
text: Meet me at home

You can also test the gateway (incoming and outgoing) for free from your browser

How to write a file with C in Linux?

You have to do write in the same loop as read.

ARM compilation error, VFP registers used by executable, not object file

Use the same compiler options for linking also.

Example:

gcc  -mfloat-abi=hard fpu=neon -c -o test.cpp test.o
gcc  -mfloat-abi=hard fpu=neon -c test1.cpp test1.o
gcc test.o test1.o mfloat-abi=hard fpu=neon HardTest

Python basics printing 1 to 100

The answers here have pointed out that because after incrementing count it doesn't equal exactly 100, then it keeps going as the criteria isn't met (it's likely you want < to say less than 100).

I'll just add that you should really be looking at Python's builtin range function which generates a sequence of integers from a starting value, up to (but not including) another value, and an optional step - so you can adjust from adding 1 or 3 or 9 at a time...

0-100 (but not including 100, defaults starting from 0 and stepping by 1):

for number in range(100):
    print(number)

0-100 (but not including and makes sure number doesn't go above 100) in steps of 3:

for number in range(0, 100, 3):
    print(number)

How do I get the path and name of the file that is currently executing?

I wrote a function which take into account eclipse debugger and unittest. It return the folder of the first script you launch. You can optionally specify the __file__ var, but the main thing is that you don't have to share this variable across all your calling hierarchy.

Maybe you can handle others stack particular cases I didn't see, but for me it's ok.

import inspect, os
def getRootDirectory(_file_=None):
    """
    Get the directory of the root execution file
    Can help: http://stackoverflow.com/questions/50499/how-do-i-get-the-path-and-name-of-the-file-that-is-currently-executing
    For eclipse user with unittest or debugger, the function search for the correct folder in the stack
    You can pass __file__ (with 4 underscores) if you want the caller directory
    """
    # If we don't have the __file__ :
    if _file_ is None:
        # We get the last :
        rootFile = inspect.stack()[-1][1]
        folder = os.path.abspath(rootFile)
        # If we use unittest :
        if ("/pysrc" in folder) & ("org.python.pydev" in folder):
            previous = None
            # We search from left to right the case.py :
            for el in inspect.stack():
                currentFile = os.path.abspath(el[1])
                if ("unittest/case.py" in currentFile) | ("org.python.pydev" in currentFile):
                    break
                previous = currentFile
            folder = previous
        # We return the folder :
        return os.path.dirname(folder)
    else:
        # We return the folder according to specified __file__ :
        return os.path.dirname(os.path.realpath(_file_))

SQL TRUNCATE DATABASE ? How to TRUNCATE ALL TABLES

Taking a point from both Boycs Answer and mtmurdock's subsequent answer I have the following stored proc on all of my development or staging databases. I've added some switches to fit my own requirement if I need to add in statements to reseed the data for certain columns.

(Note: I would have added this as a comment to Boycs brilliant answer but I haven't got enough reputation to do that yet. So please accept my apologies for adding this as an entirely new answer.)

ALTER PROCEDURE up_ResetEntireDatabase
@IncludeIdentReseed BIT,
@IncludeDataReseed BIT
AS

EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'
EXEC sp_MSForEachTable 'DELETE FROM ?'

IF @IncludeIdentReseed = 1
BEGIN
    EXEC sp_MSForEachTable 'DBCC CHECKIDENT (''?'' , RESEED, 1)'
END

EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL'

IF @IncludeDataReseed = 1
BEGIN
    -- Populate Core Data Table Here
END
GO

And then once ready the execution is really simple:

EXEC up_ResetEntireDatabase 1, 1

Foreign keys in mongo?

How to design table like this in mongodb?

First, to clarify some naming conventions. MongoDB uses collections instead of tables.

I think there are no foreign keys!

Take the following model:

student
{ 
  _id: ObjectId(...),
  name: 'Jane',
  courses: [
    { course: 'bio101', mark: 85 },
    { course: 'chem101', mark: 89 }
  ]
}

course
{
  _id: 'bio101',
  name: 'Biology 101',
  description: 'Introduction to biology'
}

Clearly Jane's course list points to some specific courses. The database does not apply any constraints to the system (i.e.: foreign key constraints), so there are no "cascading deletes" or "cascading updates". However, the database does contain the correct information.

In addition, MongoDB has a DBRef standard that helps standardize the creation of these references. In fact, if you take a look at that link, it has a similar example.

How can I solve this task?

To be clear, MongoDB is not relational. There is no standard "normal form". You should model your database appropriate to the data you store and the queries you intend to run.

Color theme for VS Code integrated terminal

Simply. You can go to 'File -> Preferences -> Color Theme' option in visual studio and change the color of you choice.

Using variables inside strings

Up to C#5 (-VS2013) you have to call a function/method for it. Either a "normal" function such as String.Format or an overload of the + operator.

string str = "Hello " + name; // This calls an overload of operator +.

In C#6 (VS2015) string interpolation has been introduced (as described by other answers).

How can I split a shell command over multiple lines when using an IF statement?

For Windows/WSL/Cygwin etc users:

Make sure that your line endings are standard Unix line feeds, i.e. \n (LF) only.

Using Windows line endings \r\n (CRLF) line endings will break the command line break.


This is because having \ at the end of a line with Windows line ending translates to \ \r \n.
As Mark correctly explains above:

The line-continuation will fail if you have whitespace after the backslash and before the newline.

This includes not just space () or tabs (\t) but also the carriage return (\r).

Addressing localhost from a VirtualBox virtual machine

In Virtual Box

  1. Set your network to Bridge networking
  2. Go to Advanced set Promiscuous Mode: Allow All

Now the tricky bit is your localhost, if you are running from Node.js set the IP address to 0.0.0.0, then lookup your own IP address, for example cmd:ipconfig --> 10.0.1.3

Type that address in with the port number. And it will work.

Python extending with - using super() Python 3 vs Python 2

In short, they are equivalent. Let's have a history view:

(1) at first, the function looks like this.

    class MySubClass(MySuperClass):
        def __init__(self):
            MySuperClass.__init__(self)

(2) to make code more abstract (and more portable). A common method to get Super-Class is invented like:

    super(<class>, <instance>)

And init function can be:

    class MySubClassBetter(MySuperClass):
        def __init__(self):
            super(MySubClassBetter, self).__init__()

However requiring an explicit passing of both the class and instance break the DRY (Don't Repeat Yourself) rule a bit.

(3) in V3. It is more smart,

    super()

is enough in most case. You can refer to http://www.python.org/dev/peps/pep-3135/

checking if a number is divisible by 6 PHP

$num += (6-$num%6)%6;

no need for a while loop! Modulo (%) returns the remainder of a division. IE 20%6 = 2. 6-2 = 4. 20+4 = 24. 24 is divisible by 6.

Why calling react setState method doesn't mutate the state immediately?

Simply putting - this.setState({data: value}) is asynchronous in nature that means it moves out of the Call Stack and only comes back to the Call Stack unless it is resolved.

Please read about Event Loop to have a clear picture about Asynchronous nature in JS and why it takes time to update -

https://medium.com/front-end-weekly/javascript-event-loop-explained-4cd26af121d4

Hence -

    this.setState({data:value});
    console.log(this.state.data); // will give undefined or unupdated value

as it takes time to update. To achieve the above process -

    this.setState({data:value},function () {
     console.log(this.state.data);
    });

How can I display an image from a file in Jupyter Notebook?

A cleaner Python3 version that use standard numpy, matplotlib and PIL. Merging the answer for opening from URL.

import matplotlib.pyplot as plt
from PIL import Image
import numpy as np

pil_im = Image.open('image.png') #Take jpg + png
## Uncomment to open from URL
#import requests
#r = requests.get('https://www.vegvesen.no/public/webkamera/kamera?id=131206')
#pil_im = Image.open(BytesIO(r.content))
im_array = np.asarray(pil_im)
plt.imshow(im_array)
plt.show()

What do the different readystates in XMLHttpRequest mean, and how can I use them?

kieron's answer contains w3schools ref. to which nobody rely , bobince's answer gives link , which actually tells native implementation of IE ,

so here is the original documentation quoted to rightly understand what readystate represents :

The XMLHttpRequest object can be in several states. The readyState attribute must return the current state, which must be one of the following values:

UNSENT (numeric value 0)
The object has been constructed.

OPENED (numeric value 1)
The open() method has been successfully invoked. During this state request headers can be set using setRequestHeader() and the request can be made using the send() method.

HEADERS_RECEIVED (numeric value 2)
All redirects (if any) have been followed and all HTTP headers of the final response have been received. Several response members of the object are now available.

LOADING (numeric value 3)
The response entity body is being received.

DONE (numeric value 4)
The data transfer has been completed or something went wrong during the transfer (e.g. infinite redirects).

Please Read here : W3C Explaination Of ReadyState

javascript unexpected identifier

In such cases, you are better off re-adding the whitespace which makes the syntax error immediate apparent:

function(){
  if(xmlhttp.readyState==4&&xmlhttp.status==200){
    document.getElementById("content").innerHTML=xmlhttp.responseText;
  }
}
xmlhttp.open("GET","data/"+id+".html",true);xmlhttp.send();
}

There's a } too many. Also, after the closing } of the function, you should add a ; before the xmlhttp.open()

And finally, I don't see what that anonymous function does up there. It's never executed or referenced. Are you sure you pasted the correct code?

How to get .app file of a xcode application

Xcode 8.1

Product -> Archive Then export on the right hand side to somewhere on your drive.

Bootstrap 3 offset on right not left

Here is the same solution than Rukshan but in sass (in order to keep your grid configuration) for special case that don't work with Ross Allen solution (when you can't have a parent div.row)

@mixin make-grid-offset-right($class) {
    @for $index from 0 through $grid-columns {
        .col-#{$class}-offset-right-#{$index} {
            margin-right: percentage(($index / $grid-columns));
        }
    }
}

@include make-grid-offset-right(xs);

@media (min-width: $screen-sm-min) {
  @include make-grid-offset-right(sm);
}

@media (min-width: $screen-md-min) {
  @include make-grid-offset-right(md);
}

@media (min-width: $screen-lg-min) {
  @include make-grid-offset-right(lg);
}

How do you install GLUT and OpenGL in Visual Studio 2012?

OpenGL should be present already - it will probably be Freeglut / GLUT that is missing.

GLUT is very dated now and not actively supported - so you should certainly be using Freeglut instead. You won't have to change your code at all, and a few additional features become available.

You'll find pre-packaged sets of files from here: http://freeglut.sourceforge.net/index.php#download If you don't see the "lib" folder, it's because you didn't download the pre-packaged set. "Martin Payne's Windows binaries" is posted at above link and works on Windows 8.1 with Visual Studio 2013 at the time of this writing.

When you download these you'll find that the Freeglut folder has three subfolders: - bin folder: this contains the dll files for runtime - include: the header files for compilation - lib: contains library files for compilation/linking

Installation instructions usually suggest moving these files into the visual studio folder and the Windows system folder: It is best to avoid doing this as it makes your project less portable, and makes it much more difficult if you ever need to change which version of the library you are using (old projects might suddenly stop working, etc.)

Instead (apologies for any inconsistencies, I'm basing these instructions on VS2010)... - put the freeglut folder somewhere else, e.g. C:\dev - Open your project in Visual Studio - Open project properties - There should be a tab for VC++ Directories, here you should add the appropriate include and lib folders, e.g.: C:\dev\freeglut\include and C:\dev\freeglut\lib - (Almost) Final step is to ensure that the opengl lib file is actually linked during compilation. Still in project properties, expand the linker menu, and open the input tab. For Additional Dependencies add opengl32.lib (you would assume that this would be linked automatically just by adding the include GL/gl.h to your project, but for some reason this doesn't seem to be the case)

At this stage your project should compile OK. To actually run it, you also need to copy the freeglut.dll files into your project folder

Jquery UI Datepicker not displaying

I changed the line

.ui-helper-hidden-accessible { position: absolute !important; clip: rect(1px 1px 1px 1px); clip: rect(1px,1px,1px,1px); }

to

.ui-helper-hidden-accessible { position: absolute !important; }

and everything works now. Otherwise try upping the z-index as Soldierflup suggested.

Load RSA public key from file

This program is doing almost everything with Public and private keys. The der format can be obtained but saving raw data ( without encoding base64). I hope this helps programmers.

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import sun.security.pkcs.PKCS8Key;
import sun.security.pkcs10.PKCS10;
import sun.security.x509.X500Name;

import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;



/**
 * @author Desphilboy
 * DorOd bar shomA barobach
 *
 */
public class csrgenerator {

    private static PublicKey publickey= null;
    private static PrivateKey privateKey=null;
    //private static PKCS8Key privateKey=null;
    private static KeyPairGenerator kpg= null;
    private static ByteArrayOutputStream bs =null;
    private static csrgenerator thisinstance;
    private KeyPair keypair;
    private static PKCS10 pkcs10;
    private String signaturealgorithm= "MD5WithRSA";

    public String getSignaturealgorithm() {
        return signaturealgorithm;
    }



    public void setSignaturealgorithm(String signaturealgorithm) {
        this.signaturealgorithm = signaturealgorithm;
    }



    private csrgenerator() {
        try {
           kpg = KeyPairGenerator.getInstance("RSA");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            System.out.print("No such algorithm RSA in constructor csrgenerator\n");
        }
        kpg.initialize(2048);
        keypair = kpg.generateKeyPair();
        publickey = keypair.getPublic();
        privateKey = keypair.getPrivate();
    }



    /** Generates a new key pair 
    *
    * @param int bits 
    *   this is the number of bits in modulus must be 512, 1024, 2048  or so on 
    */
    public KeyPair generateRSAkys(int bits)
    {
          kpg.initialize(bits);
            keypair = kpg.generateKeyPair();
            publickey = keypair.getPublic();
            privateKey = keypair.getPrivate();
            KeyPair dup= keypair;
     return dup;
    }

     public static csrgenerator getInstance() {
            if (thisinstance == null)
                thisinstance = new csrgenerator();
            return thisinstance;
        }


     /**
      *  Returns a CSR as string  
      * @param cn  Common Name
      * @param OU  Organizational Unit 
      * @param Org  Organization
      * @param LocName Location name
      * @param Statename  State/Territory/Province/Region
      * @param Country    Country
      * @return     returns  csr as string.
      * @throws Exception
      */
     public String getCSR(String commonname, String organizationunit, String organization,String localname, String statename, String country ) throws Exception {
            byte[] csr = generatePKCS10(commonname, organizationunit, organization, localname, statename, country,signaturealgorithm);
            return new String(csr);
        }

     /** This function generates a new Certificate 
      * Signing Request. 
     *
     * @param CN
     *            Common Name, is X.509 speak for the name that distinguishes
     *            the Certificate best, and ties it to your Organization
     * @param OU
     *            Organizational unit
     * @param O
     *            Organization NAME
     * @param L
     *            Location
     * @param S
     *            State
     * @param C
     *            Country
     * @return    byte stream of generated request
     * @throws Exception
     */
    private static byte[] generatePKCS10(String CN, String OU, String O,String L, String S, String C,String sigAlg) throws Exception {
        // generate PKCS10 certificate request

        pkcs10 = new PKCS10(publickey);
       Signature   signature = Signature.getInstance(sigAlg);
        signature.initSign(privateKey);
        // common, orgUnit, org, locality, state, country
        //X500Name(String commonName, String organizationUnit,String organizationName,Local,State, String country)
        X500Name x500Name = new X500Name(CN, OU, O, L, S, C);
        pkcs10.encodeAndSign(x500Name,signature);
        bs = new ByteArrayOutputStream();
        PrintStream ps = new PrintStream(bs);
        pkcs10.print(ps);
        byte[] c = bs.toByteArray();
        try {
            if (ps != null)
                ps.close();
            if (bs != null)
                bs.close();
        } catch (Throwable th) {
        }
        return c;
    }

    public  PublicKey getPublicKey() {
        return publickey;
    }




    /**
     * @return
     */
    public PrivateKey getPrivateKey() {
        return privateKey;
    }

    /**
     * saves private key to a file
     * @param filename
     */
    public  void SavePrivateKey(String filename)
    {
        PKCS8EncodedKeySpec pemcontents=null;
        pemcontents= new PKCS8EncodedKeySpec( privateKey.getEncoded());
        PKCS8Key pemprivatekey= new  PKCS8Key( );
        try {
            pemprivatekey.decode(pemcontents.getEncoded());
        } catch (InvalidKeyException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        File file=new File(filename);
        try {

            file.createNewFile();
            FileOutputStream fos=new FileOutputStream(file);
            fos.write(pemprivatekey.getEncoded());
            fos.flush();
            fos.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }



    /**
     * Saves Certificate Signing Request to a file;
     * @param filename  is a String containing full path to the file which will be created containing the CSR.
     */
    public void SaveCSR(String filename)
    {
        FileOutputStream fos=null;
        PrintStream ps=null;
        File file;
        try {

            file = new File(filename);
            file.createNewFile();
            fos = new FileOutputStream(file);
            ps= new PrintStream(fos);
        }catch (IOException e)
        {
            System.out.print("\n could not open the file "+ filename);
        }

        try {
            try {
                pkcs10.print(ps);
            } catch (SignatureException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            ps.flush();
            ps.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            System.out.print("\n cannot write to the file "+ filename);
            e.printStackTrace();

        }

        }


    /**
     * Saves both public key and private  key to file names specified
     * @param fnpub  file name of public key
     * @param fnpri  file name of private key
     * @throws IOException
     */
    public static void SaveKeyPair(String fnpub,String fnpri) throws IOException { 

// Store Public Key.
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
publickey.getEncoded());
FileOutputStream fos = new FileOutputStream(fnpub);
fos.write(x509EncodedKeySpec.getEncoded());
fos.close();

// Store Private Key.
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(privateKey.getEncoded());
fos = new FileOutputStream(fnpri);
fos.write(pkcs8EncodedKeySpec.getEncoded());
fos.close();
}


    /**
     * Reads a Private Key from a pem base64 encoded file.
     * @param filename name of the file to read.
     * @param algorithm Algorithm is usually "RSA"
     * @return returns the privatekey which is read from the file;
     * @throws Exception
     */
    public  PrivateKey getPemPrivateKey(String filename, String algorithm) throws Exception {
          File f = new File(filename);
          FileInputStream fis = new FileInputStream(f);
          DataInputStream dis = new DataInputStream(fis);
          byte[] keyBytes = new byte[(int) f.length()];
          dis.readFully(keyBytes);
          dis.close();

          String temp = new String(keyBytes);
          String privKeyPEM = temp.replace("-----BEGIN PRIVATE KEY-----", "");
          privKeyPEM = privKeyPEM.replace("-----END PRIVATE KEY-----", "");
          //System.out.println("Private key\n"+privKeyPEM);

          BASE64Decoder b64=new BASE64Decoder();
          byte[] decoded = b64.decodeBuffer(privKeyPEM);

          PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
          KeyFactory kf = KeyFactory.getInstance(algorithm);
          return kf.generatePrivate(spec);
          }



    /**
     * Saves the private key to a pem file.
     * @param filename  name of the file to write the key into 
     * @param key the Private key to save.
     * @return  String representation of the pkcs8 object.
     * @throws Exception
     */
    public  String  SavePemPrivateKey(String filename) throws Exception {
        PrivateKey key=this.privateKey;
          File f = new File(filename);
          FileOutputStream fos = new FileOutputStream(f);
          DataOutputStream dos = new DataOutputStream(fos);


          byte[] keyBytes = key.getEncoded();
          PKCS8Key pkcs8= new PKCS8Key();
          pkcs8.decode(keyBytes);
          byte[] b=pkcs8.encode();

          BASE64Encoder b64=new BASE64Encoder();
          String  encoded = b64.encodeBuffer(b);

          encoded= "-----BEGIN PRIVATE KEY-----\r\n" + encoded + "-----END PRIVATE KEY-----";

         dos.writeBytes(encoded);
         dos.flush();
         dos.close();

          //System.out.println("Private key\n"+privKeyPEM);
        return pkcs8.toString();

          }


    /**
     * Saves a public key to a base64 encoded pem file
     * @param filename  name of the file 
     * @param key public key to be saved 
     * @return string representation of the pkcs8 object.
     * @throws Exception
     */
    public  String  SavePemPublicKey(String filename) throws Exception {
        PublicKey key=this.publickey;  
        File f = new File(filename);
          FileOutputStream fos = new FileOutputStream(f);
          DataOutputStream dos = new DataOutputStream(fos);


          byte[] keyBytes = key.getEncoded();
          BASE64Encoder b64=new BASE64Encoder();
          String  encoded = b64.encodeBuffer(keyBytes);

          encoded= "-----BEGIN PUBLIC KEY-----\r\n" + encoded + "-----END PUBLIC KEY-----";

         dos.writeBytes(encoded);
         dos.flush();
         dos.close();

          //System.out.println("Private key\n"+privKeyPEM);
      return  encoded.toString();

          }





       /**
     * reads a public key from a file
     * @param filename name of the file to read
     * @param algorithm is usually RSA
     * @return the read public key
     * @throws Exception
     */
    public  PublicKey getPemPublicKey(String filename, String algorithm) throws Exception {
          File f = new File(filename);
          FileInputStream fis = new FileInputStream(f);
          DataInputStream dis = new DataInputStream(fis);
          byte[] keyBytes = new byte[(int) f.length()];
          dis.readFully(keyBytes);
          dis.close();

          String temp = new String(keyBytes);
          String publicKeyPEM = temp.replace("-----BEGIN PUBLIC KEY-----\n", "");
          publicKeyPEM = publicKeyPEM.replace("-----END PUBLIC KEY-----", "");


          BASE64Decoder b64=new BASE64Decoder();
          byte[] decoded = b64.decodeBuffer(publicKeyPEM);

          X509EncodedKeySpec spec =
                new X509EncodedKeySpec(decoded);
          KeyFactory kf = KeyFactory.getInstance(algorithm);
          return kf.generatePublic(spec);
          }




    public static void main(String[] args) throws Exception {
        csrgenerator gcsr = csrgenerator.getInstance();
        gcsr.setSignaturealgorithm("SHA512WithRSA");
        System.out.println("Public Key:\n"+gcsr.getPublicKey().toString());

        System.out.println("Private Key:\nAlgorithm: "+gcsr.getPrivateKey().getAlgorithm().toString());
        System.out.println("Format:"+gcsr.getPrivateKey().getFormat().toString());
        System.out.println("To String :"+gcsr.getPrivateKey().toString());
        System.out.println("GetEncoded :"+gcsr.getPrivateKey().getEncoded().toString());
        BASE64Encoder encoder= new BASE64Encoder();
        String s=encoder.encodeBuffer(gcsr.getPrivateKey().getEncoded());
        System.out.println("Base64:"+s+"\n");

        String csr = gcsr.getCSR( "[email protected]","baxshi az xodam", "Xodam","PointCook","VIC" ,"AU");
        System.out.println("CSR Request Generated!!");
        System.out.println(csr);
        gcsr.SaveCSR("c:\\testdir\\javacsr.csr");
        String p=gcsr.SavePemPrivateKey("c:\\testdir\\java_private.pem");
        System.out.print(p);
        p=gcsr.SavePemPublicKey("c:\\testdir\\java_public.pem");
        privateKey= gcsr.getPemPrivateKey("c:\\testdir\\java_private.pem", "RSA");
        BASE64Encoder encoder1= new BASE64Encoder();
        String s1=encoder1.encodeBuffer(gcsr.getPrivateKey().getEncoded());
        System.out.println("Private Key in Base64:"+s1+"\n");
        System.out.print(p);


    }

    }

Use multiple css stylesheets in the same html page

You never refer to a specific style sheet. All CSS rules in a document are internally fused into one.

In the case of rules in both style sheets that apply to the same element with the same specificity, the style sheet embedded later will override the earlier one.

You can use an element inspector like Firebug to see which rules apply, and which ones are overridden by others.

Compilation fails with "relocation R_X86_64_32 against `.rodata.str1.8' can not be used when making a shared object"

I'm getting the same solution as @camino's comment on https://stackoverflow.com/a/19365454/10593190 and XavierStuvw's reply.

I got it to work (for installing ffmpeg) by simply reinstalling the whole thing from the beginning with all instances of $ ./configure replaced by $ ./configure --enable-shared (first make sure to delete all the folders and files including the .so files from the previous attempt).

Apparently this works because https://stackoverflow.com/a/13812368/10593190.

How do I open multiple instances of Visual Studio Code?

Multiple instances of the same project

WORKAROUND

You cannot open multiple instances of the same folder but a workaround I have found is to open different folders.

lib
-components
-models
-helpers
tests

So, here I might open components, models and tests in different windows and then I can view them on my three monitors.

It sounds a bit simple but this has helped me a lot.

Run cURL commands from Windows console

it should work perfectly fine if you would download it from --http://curl.haxx.se/dlwiz/?type=bin&os=Win64&flav=MinGW64 -- FOR 64BIT Win7/XP OR from http://curl.haxx.se/dlwiz/?type=bin&os=Win32&flav=-&ver=2000%2FXP --- FOR 32BIT Win7/XP just extract the files to c:/Windows and run it from cmd

C:\Users\WaQas>curl -v google.com
* About to connect() to google.com port 80 (#0)
*   Trying 173.194.35.105...
* connected
* Connected to google.com (173.194.35.105) port 80 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.28.1
> Host: google.com
> Accept: */*
>
* HTTP 1.0, assume close after body
< HTTP/1.0 301 Moved Permanently
< Location: http://www.google.com/
< Content-Type: text/html; charset=UTF-8
< Date: Tue, 05 Feb 2013 00:50:57 GMT
< Expires: Thu, 07 Mar 2013 00:50:57 GMT
< Cache-Control: public, max-age=2592000
< Server: gws
< Content-Length: 219
< X-XSS-Protection: 1; mode=block
< X-Frame-Options: SAMEORIGIN
< X-Cache: MISS from LHR-CacheMARA3
< X-Cache-Lookup: HIT from LHR-CacheMARA3:64003
< Connection: close
<
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>
* Closing connection #0

Find and extract a number from a string

Here's a Linq version:

string s = "123iuow45ss";
var getNumbers = (from t in s
                  where char.IsDigit(t)
                  select t).ToArray();
Console.WriteLine(new string(getNumbers));

Vue-router redirect on page not found (404)

@mani's response is now slightly outdated as using catch-all '*' routes is no longer supported when using Vue 3 onward. If this is no longer working for you, try replacing the old catch-all path with

{ path: '/:pathMatch(.*)*', component: PathNotFound },

Essentially, you should be able to replace the '*' path with '/:pathMatch(.*)*' and be good to go!

Reason: Vue Router doesn't use path-to-regexp anymore, instead it implements its own parsing system that allows route ranking and enables dynamic routing. Since we usually add one single catch-all route per project, there is no big benefit in supporting a special syntax for *.

(from https://next.router.vuejs.org/guide/migration/#removed-star-or-catch-all-routes)

Easy interview question got harder: given numbers 1..100, find the missing number(s) given exactly k are missing

This might sound stupid, but, in the first problem presented to you, you would have to see all the remaining numbers in the bag to actually add them up to find the missing number using that equation.

So, since you get to see all the numbers, just look for the number that's missing. The same goes for when two numbers are missing. Pretty simple I think. No point in using an equation when you get to see the numbers remaining in the bag.

DB2 SQL error sqlcode=-104 sqlstate=42601

You miss the from clause

SELECT *  from TCCAWZTXD.TCC_COIL_DEMODATA WHERE CURRENT_INSERTTIME  BETWEEN(CURRENT_TIMESTAMP)-5 minutes AND CURRENT_TIMESTAMP

jQuery add required to input fields

Using .attr method

.attr(attribute,value); // syntax

.attr("required", true);
// required="required"

.attr("required", false);
// 

Using .prop

.prop(property,value) // syntax

.prop("required", true);
// required=""

.prop("required", false);
//

Read more from here

https://stackoverflow.com/a/5876747/5413283

How to rollback just one step using rake db:migrate

For starters

rake db:rollback will get you back one step

then

rake db:rollback STEP=n

Will roll you back n migrations where n is the number of recent migrations you want to rollback.

More references here.

How to "pull" from a local branch into another one?

Quite old post, but it might help somebody new into git.

I will go with

git rebase master
  • much cleaner log history and no merge commits (if done properly)
  • need to deal with conflicts, but it's not that difficult.

How to convert date format to milliseconds?

long millisecond = beginupd.getTime();

Date.getTime() JavaDoc states:

Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.

How do I check the operating system in Python?

If you want to know on which platform you are on out of "Linux", "Windows", or "Darwin" (Mac), without more precision, you should use:

>>> import platform
>>> platform.system()
'Linux'  # or 'Windows'/'Darwin'

The platform.system function uses uname internally.

How can bcrypt have built-in salts?

I believe that phrase should have been worded as follows:

bcrypt has salts built into the generated hashes to prevent rainbow table attacks.

The bcrypt utility itself does not appear to maintain a list of salts. Rather, salts are generated randomly and appended to the output of the function so that they are remembered later on (according to the Java implementation of bcrypt). Put another way, the "hash" generated by bcrypt is not just the hash. Rather, it is the hash and the salt concatenated.

How to change the icon of an Android app in Eclipse?

In your AndroidManifest.xml file

<application
        android:name="ApplicationClass"
        android:icon="@drawable/ic_launcher"  <--------
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >

Add up a column of numbers at the Unix shell

Pipe to gawk:

 cat files.txt | xargs ls -l | cut -c 23-30 | gawk 'BEGIN { sum = 0 } // { sum = sum + $0 } END { print sum }'

Hide password with "•••••••" in a textField

in Swift 3.0 or Later

passwordTextField.isSecureTextEntry = true

Ternary operator (?:) in Bash

[ $b == 5 ] && { a=$c; true; } || a=$d

This will avoid executing the part after || by accident when the code between && and || fails.

How do I set a column value to NULL in SQL Server Management Studio?

I think @Zack properly answered the question but just to cover all the bases:

Update myTable set MyColumn = NULL

This would set the entire column to null as the Question Title asks.

To set a specific row on a specific column to null use:

Update myTable set MyColumn = NULL where Field = Condition.

This would set a specific cell to null as the inner question asks.