Programs & Examples On #Folksonomy

proper way to logout from a session in PHP

Session_unset(); only destroys the session variables. To end the session there is another function called session_destroy(); which also destroys the session .

update :

In order to kill the session altogether, like to log the user out, the session id must also be unset. If a cookie is used to propagate the session id (default behavior), then the session cookie must be deleted. setcookie() may be used for that

DateTime fields from SQL Server display incorrectly in Excel

Found a solution that doesnt requires to remember and retype the custom datetime format yyyy-mm-dd hh:mm:ss.000

  • On a new cell, write either =NOW() or any valid date+time like 5/30/2017 17:35: It will display correctly in your language, e.g. 5/30/2017 5:35:00 PM
  • Select the cell, click on the Format Painter icon (the paint brush)
  • Now click on the row header of the column that you want to apply the format.

This will copy a proper datetime format to the whole column, making it display correctly.

XSLT - How to select XML Attribute by Attribute?

Note: using // at the beginning of the xpath is a bit CPU intensitve -- it will search every node for a match. Using a more specific path, such as /root/DataSet will create a faster query.

Convert List<Object> to String[] in Java

Java 8 has the option of using streams like:

List<Object> lst = new ArrayList<>();
String[] strings = lst.stream().toArray(String[]::new);

Read a file line by line with VB.NET

Replaced the reader declaration with this one and now it works!

Dim reader As New StreamReader(filetoimport.Text, Encoding.Default)

Encoding.Default represents the ANSI code page that is set under Windows Control Panel.

How to remove an element from a list by index

If you want to remove the specific position element in a list, like the 2th, 3th and 7th. you can't use

del my_list[2]
del my_list[3]
del my_list[7]

Since after you delete the second element, the third element you delete actually is the fourth element in the original list. You can filter the 2th, 3th and 7th element in the original list and get a new list, like below:

new list = [j for i, j in enumerate(my_list) if i not in [2, 3, 7]]

How to upload a file in Django?

You can refer to server examples in Fine Uploader, which has django version. https://github.com/FineUploader/server-examples/tree/master/python/django-fine-uploader

It's very elegant and most important of all, it provides featured js lib. Template is not included in server-examples, but you can find demo on its website. Fine Uploader: http://fineuploader.com/demos.html

django-fine-uploader

views.py

UploadView dispatches post and delete request to respective handlers.

class UploadView(View):

    @csrf_exempt
    def dispatch(self, *args, **kwargs):
        return super(UploadView, self).dispatch(*args, **kwargs)

    def post(self, request, *args, **kwargs):
        """A POST request. Validate the form and then handle the upload
        based ont the POSTed data. Does not handle extra parameters yet.
        """
        form = UploadFileForm(request.POST, request.FILES)
        if form.is_valid():
            handle_upload(request.FILES['qqfile'], form.cleaned_data)
            return make_response(content=json.dumps({ 'success': True }))
        else:
            return make_response(status=400,
                content=json.dumps({
                    'success': False,
                    'error': '%s' % repr(form.errors)
                }))

    def delete(self, request, *args, **kwargs):
        """A DELETE request. If found, deletes a file with the corresponding
        UUID from the server's filesystem.
        """
        qquuid = kwargs.get('qquuid', '')
        if qquuid:
            try:
                handle_deleted_file(qquuid)
                return make_response(content=json.dumps({ 'success': True }))
            except Exception, e:
                return make_response(status=400,
                    content=json.dumps({
                        'success': False,
                        'error': '%s' % repr(e)
                    }))
        return make_response(status=404,
            content=json.dumps({
                'success': False,
                'error': 'File not present'
            }))

forms.py

class UploadFileForm(forms.Form):

    """ This form represents a basic request from Fine Uploader.
    The required fields will **always** be sent, the other fields are optional
    based on your setup.
    Edit this if you want to add custom parameters in the body of the POST
    request.
    """
    qqfile = forms.FileField()
    qquuid = forms.CharField()
    qqfilename = forms.CharField()
    qqpartindex = forms.IntegerField(required=False)
    qqchunksize = forms.IntegerField(required=False)
    qqpartbyteoffset = forms.IntegerField(required=False)
    qqtotalfilesize = forms.IntegerField(required=False)
    qqtotalparts = forms.IntegerField(required=False)

Appending the same string to a list of strings in Python

list2 = ['%sbar' % (x,) for x in list]

And don't use list as a name; it shadows the built-in type.

How to edit hosts file via CMD?

echo 0.0.0.0 websitename.com >> %WINDIR%\System32\Drivers\Etc\Hosts

the >> appends the output of echo to the file.

Note that there are two reasons this might not work like you want it to. You may be aware of these, but I mention them just in case.

First, it won't affect a web browser, for example, that already has the current, "real" IP address resolved. So, it won't always take effect right away.

Second, it requires you to add an entry for every host name on a domain; just adding websitename.com will not block www.websitename.com, for example.

Selenium -- How to wait until page is completely loaded

There are two different ways to use delay in selenium one which is most commonly in use. Please try this:

driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);

second one which you can use that is simply try catch method by using that method you can get your desire result.if you want example code feel free to contact me defiantly I will provide related code

Easiest way to activate PHP and MySQL on Mac OS 10.6 (Snow Leopard), 10.7 (Lion), 10.8 (Mountain Lion)?

Considering it hasn't been released yet, I'm assuming this is a question for ahead-of-time or you have a developer's build. As Benjamin mentioned, MAMP is the easiest way. However, if you want a native install, the process should be like 10.5. PHP comes installed on OS X by default (not always activated for some), just download the 32-bit version of MySQL, start Apache, and you should be good to go. You may have to tweak Apache for PHP or MySQL, depending on what builds are present. I didn't have to tweak anything to have it working.

Java Singleton and Synchronization

Yes, it is necessary. There are several methods you can use to achieve thread safety with lazy initialization:

Draconian synchronization:

private static YourObject instance;

public static synchronized YourObject getInstance() {
    if (instance == null) {
        instance = new YourObject();
    }
    return instance;
}

This solution requires that every thread be synchronized when in reality only the first few need to be.

Double check synchronization:

private static final Object lock = new Object();
private static volatile YourObject instance;

public static YourObject getInstance() {
    YourObject r = instance;
    if (r == null) {
        synchronized (lock) {    // While we were waiting for the lock, another 
            r = instance;        // thread may have instantiated the object.
            if (r == null) {  
                r = new YourObject();
                instance = r;
            }
        }
    }
    return r;
}

This solution ensures that only the first few threads that try to acquire your singleton have to go through the process of acquiring the lock.

Initialization on Demand:

private static class InstanceHolder {
    private static final YourObject instance = new YourObject();
}

public static YourObject getInstance() {
    return InstanceHolder.instance;
}

This solution takes advantage of the Java memory model's guarantees about class initialization to ensure thread safety. Each class can only be loaded once, and it will only be loaded when it is needed. That means that the first time getInstance is called, InstanceHolder will be loaded and instance will be created, and since this is controlled by ClassLoaders, no additional synchronization is necessary.

Java ArrayList for integers

How about creating an ArrayList of a set amount of Integers?

The below method returns an ArrayList of a set amount of Integers.

public static ArrayList<Integer> createRandomList(int sizeParameter)
{
    // An ArrayList that method returns
    ArrayList<Integer> setIntegerList = new ArrayList<Integer>(sizeParameter);
    // Random Object helper
    Random randomHelper = new Random();
    
    for (int x = 0; x < sizeParameter; x++)
    {
        setIntegerList.add(randomHelper.nextInt());
    }   // End of the for loop
    
    return setIntegerList;
}

How do I control how Emacs makes backup files?

You can disable them altogether by

(setq make-backup-files nil)

How to make a drop down list in yii2?

It Seems there are many good answers for this question .So i will try to give a detailed answer

active form and hardcoded data

<?php
    echo $form->field($model, 'name')->dropDownList(['1' => 'Yes', '0' => 'No'],['prompt'=>'Select Option']);
?>

or

<?php
    $a= ['1' => 'Yes', '0' => 'No'];
    echo $form->field($model, 'name')->dropDownList($a,['prompt'=>'Select Option']);
?>

active form and data from a db table

we are going to use ArrayHelper so first add it to the name space by

<?php
    use yii\helpers\ArrayHelper;
?>

ArrayHelper has many use full functions which could be used to process arrays map () is the one we are going to use here this function help to make a map ( of key-value pairs) from a multidimensional array or an array of objects.

<?php
    echo $form->field($model, 'name')->dropDownList(ArrayHelper::map(User::find()->all(),'id','username'),['prompt'=>'Select User']);
?>

not part of a active form

<?php
    echo Html::activeDropDownList($model, 'filed_name',['1' => 'Yes', '0' => 'No']) ;
?>

or

<?php
    $a= ['1' => 'Yes', '0' => 'No'];
    echo Html::activeDropDownList($model, 'filed_name',$a) ;
?>

not an active form but data from a db table

<?php
    echo Html::activeDropDownList($model, 'filed_name',ArrayHelper::map(User::find()->all(),'id','username'),['prompt'=>'Select User']);
?>

Javascript Regexp dynamic generation from variables?

You have to forgo the regex literal and use the object constructor, where you can pass the regex as a string.

var regex = new RegExp(pattern1+'|'+pattern2, 'gi');
str.match(regex);

How do you append rows to a table using jQuery?

Maybe this is the answer you are looking for. It finds the last instance of <tr /> and appends the new row after it:

<script type="text/javascript">
    $('a').click(function() {
        $('#myTable tr:last').after('<tr class="child"><td>blahblah<\/td></tr>');
    });
</script>

How can I use the MS JDBC driver with MS SQL Server 2008 Express?

You can try the following. Works fine in my case:

  1. Download the current jTDS JDBC Driver
  2. Put jtds-x.x.x.jar in your classpath.
  3. Copy ntlmauth.dll to windows/system32. Choose the dll based on your hardware x86,x64...
  4. The connection url is: 'jdbc:jtds:sqlserver://localhost:1433/YourDB' , you don't have to provide username and password.

Hope that helps.

Using Application context everywhere?

There are a couple of potential problems with this approach, though in a lot of circumstances (such as your example) it will work well.

In particular you should be careful when dealing with anything that deals with the GUI that requires a Context. For example, if you pass the application Context into the LayoutInflater you will get an Exception. Generally speaking, your approach is excellent: it's good practice to use an Activity's Context within that Activity, and the Application Context when passing a context beyond the scope of an Activity to avoid memory leaks.

Also, as an alternative to your pattern you can use the shortcut of calling getApplicationContext() on a Context object (such as an Activity) to get the Application Context.

/usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.15' not found

Same thing with gcc version 4.8.1 (GCC) and libstdc++.so.6.0.18. Had to copy it here /usr/lib/x86_64-linux-gnu on my ubuntu box.

Is there a way to cache GitHub credentials for pushing commits?

Usually you have a remote URL, something like this,

git remote -v

origin    https://gitlab.com/username/Repo.git (fetch)
origin    https://gitlab.com/username/Repo.git (push)

If you want to skip username and password while using git push, try this:

 git remote set-url origin https://username:[email protected]/username/Repo.git

I've just added the same URL (with user details including password) to origin.

NOTE: It doesn't work if username is an email Id.

git remote -v

origin    https://username:[email protected]/username/Repo.git (fetch)
origin    https://username:[email protected]/username/Repo.git (push)

Running a Python script from PHP

In my case I needed to create a new folder in the www directory called scripts. Within scripts I added a new file called test.py.

I then used sudo chown www-data:root scripts and sudo chown www-data:root test.py.

Then I went to the new scripts directory and used sudo chmod +x test.py.

My test.py file it looks like this. Note the different Python version:

#!/usr/bin/env python3.5
print("Hello World!")

From php I now do this:

$message = exec("/var/www/scripts/test.py 2>&1");
print_r($message);

And you should see: Hello World!

Postman: sending nested JSON object

Simply add these parameters : In the header option of the request, add Content-Type:application/json

header content-type postman json

and in the body, select Raw format and put your json params like {'guid':'61791957-81A3-4264-8F32-49BCFB4544D8'}

json request postman

I've found the solution on http://www.iminfo.in/post/post-json-postman-rest-client-chrome

Loop structure inside gnuplot?

I have the script all.p

set ...
...
list=system('ls -1B *.dat')
plot for [file in list] file w l u 1:2 t file

Here the two last rows are literal, not heuristic. Then i run

$ gnuplot -p all.p

Change *.dat to the file type you have, or add file types.

Next step: Add to ~/.bashrc this line

alias p='gnuplot -p ~/./all.p'

and put your file all.p int your home directory and voila. You can plot all files in any directory by typing p and enter.

EDIT I changed the command, because it didn't work. Previously it contained list(i)=word(system(ls -1B *.dat),i).

Why I am Getting Error 'Channel is unrecoverably broken and will be disposed!'

This error occurred in case of memory leak. For example if you have any static context of an Android component (Activity/service/etc) and its gets killed by system.

Example: Music player controls in notification area. Use a foreground service and set actions in the notification channel via PendingIntent like below.

Intent notificationIntent = new Intent(this, MainActivity.class);
        notificationIntent.setAction(AppConstants.ACTION.MAIN_ACTION);
        notificationIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                | Intent.FLAG_ACTIVITY_CLEAR_TASK);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0,
                notificationIntent, 0);

        Intent previousIntent = new Intent(this, ForegroundService.class);
        previousIntent.setAction(AppConstants.ACTION.PREV_ACTION);
        PendingIntent ppreviousIntent = PendingIntent.getService(this, 0,
                previousIntent, 0);

        Intent playIntent = new Intent(this, ForegroundService.class);
        playIntent.setAction(AppConstants.ACTION.PLAY_ACTION);
        PendingIntent pplayIntent = PendingIntent.getService(this, 0,
                playIntent, 0);

        Intent nextIntent = new Intent(this, ForegroundService.class);
        nextIntent.setAction(AppConstants.ACTION.NEXT_ACTION);

        Bitmap icon = BitmapFactory.decodeResource(getResources(),
                R.drawable.ic_launcher);

        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        String NOTIFICATION_CHANNEL_ID = "my_channel_id_01";

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "My Notifications", NotificationManager.IMPORTANCE_HIGH);

            // Configure the notification channel.
            notificationChannel.setDescription("Channel description");
            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
            notificationChannel.setVibrationPattern(new long[]{0, 1000, 500, 1000});
            notificationChannel.enableVibration(true);
            notificationManager.createNotificationChannel(notificationChannel);
        }

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID);
        Notification notification = notificationBuilder
                .setOngoing(true)
                .setAutoCancel(true)
                .setWhen(System.currentTimeMillis())
                .setContentTitle("Foreground Service")
                .setContentText("Foreground Service Running")
                .setSmallIcon(R.drawable.ic_launcher)
                .setLargeIcon(Bitmap.createScaledBitmap(icon, 128, 128, false))
                .setContentIntent(pendingIntent)
                .setPriority(NotificationManager.IMPORTANCE_MAX)
                .setCategory(Notification.CATEGORY_SERVICE)
                .setTicker("Hearty365")
                .build();
        startForeground(AppConstants.NOTIFICATION_ID.FOREGROUND_SERVICE,
                notification);

And if this notification channel get broken abruptly (may be by system, like in Xiomi devices when we clean out the background apps), then due to memory leaks this error is thrown by system.

Check if input value is empty and display an alert

Check empty input with removing space(if user enter space) from input using trim

$(document).ready(function(){     
       $('#button').click(function(){
            if($.trim($('#fname').val()) == '')
           {
               $('#fname').css("border-color", "red");
               alert("Empty"); 
           }
     });
});

Check if string ends with certain pattern

You can test if a string ends with work followed by one character like this:

theString.matches(".*work.$");

If the trailing character is optional you can use this:

theString.matches(".*work.?$");

To make sure the last character is a period . or a slash / you can use this:

theString.matches(".*work[./]$");

To test for work followed by an optional period or slash you can use this:

theString.matches(".*work[./]?$");

To test for work surrounded by periods or slashes, you could do this:

theString.matches(".*[./]work[./]$");

If the tokens before and after work must match each other, you could do this:

theString.matches(".*([./])work\\1$");

Your exact requirement isn't precisely defined, but I think it would be something like this:

theString.matches(".*work[,./]?$");

In other words:

  • zero or more characters
  • followed by work
  • followed by zero or one , . OR /
  • followed by the end of the input

Explanation of various regex items:

.               --  any character
*               --  zero or more of the preceeding expression
$               --  the end of the line/input
?               --  zero or one of the preceeding expression
[./,]           --  either a period or a slash or a comma
[abc]           --  matches a, b, or c
[abc]*          --  zero or more of (a, b, or c)
[abc]?          --  zero or one of (a, b, or c)

enclosing a pattern in parentheses is called "grouping"

([abc])blah\\1  --  a, b, or c followed by blah followed by "the first group"

Here's a test harness to play with:

class TestStuff {

    public static void main (String[] args) {

        String[] testStrings = { 
                "work.",
                "work-",
                "workp",
                "/foo/work.",
                "/bar/work",
                "baz/work.",
                "baz.funk.work.",
                "funk.work",
                "jazz/junk/foo/work.",
                "funk/punk/work/",
                "/funk/foo/bar/work",
                "/funk/foo/bar/work/",
                ".funk.foo.bar.work.",
                ".funk.foo.bar.work",
                "goo/balls/work/",
                "goo/balls/work/funk"
        };

        for (String t : testStrings) {
            print("word: " + t + "  --->  " + matchesIt(t));
        }
    }

    public static boolean matchesIt(String s) {
        return s.matches(".*([./,])work\\1?$");
    }

    public static void print(Object o) {
        String s = (o == null) ? "null" : o.toString();
        System.out.println(o);
    }

}

How to remove Firefox's dotted outline on BUTTONS as well as links?

It looks like the only way to achieve this is by setting

browser.display.focus_ring_width = 0

in about:config on a per browser basis.

Check if a variable is null in plsql

In PL/SQL you can't use operators such as '=' or '<>' to test for NULL because all comparisons to NULL return NULL. To compare something against NULL you need to use the special operators IS NULL or IS NOT NULL which are there for precisely this purpose. Thus, instead of writing

IF var = NULL THEN...

you should write

IF VAR IS NULL THEN...

In the case you've given you also have the option of using the NVL built-in function. NVL takes two arguments, the first being a variable and the second being a value (constant or computed). NVL looks at its first argument and, if it finds that the first argument is NULL, returns the second argument. If the first argument to NVL is not NULL, the first argument is returned. So you could rewrite

IF var IS NULL THEN
  var := 5;
END IF;

as

var := NVL(var, 5);

I hope this helps.

EDIT

And because it's nearly ten years since I wrote this answer, let's celebrate by expanding it just a bit.

The COALESCE function is the ANSI equivalent of Oracle's NVL. It differs from NVL in a couple of IMO good ways:

  1. It takes any number of arguments, and returns the first one which is not NULL. If all the arguments passed to COALESCE are NULL, it returns NULL.

  2. In contrast to NVL, COALESCE only evaluates arguments if it must, while NVL evaluates both of its arguments and then determines if the first one is NULL, etc. So COALESCE can be more efficient, because it doesn't spend time evaluating things which won't be used (and which can potentially cause unwanted side effects), but it also means that COALESCE is not a 100% straightforward drop-in replacement for NVL.

Using Excel VBA to run SQL query

Below is code that I currently use to pull data from a MS SQL Server 2008 into VBA. You need to make sure you have the proper ADODB reference [VBA Editor->Tools->References] and make sure you have Microsoft ActiveX Data Objects 2.8 Library checked, which is the second from the bottom row that is checked (I'm using Excel 2010 on Windows 7; you might have a slightly different ActiveX version, but it will still begin with Microsoft ActiveX):

References required for SQL

Sub Module for Connecting to MS SQL with Remote Host & Username/Password

Sub Download_Standard_BOM()
'Initializes variables
Dim cnn As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim ConnectionString As String
Dim StrQuery As String

'Setup the connection string for accessing MS SQL database
   'Make sure to change:
       '1: PASSWORD
       '2: USERNAME
       '3: REMOTE_IP_ADDRESS
       '4: DATABASE
    ConnectionString = "Provider=SQLOLEDB.1;Password=PASSWORD;Persist Security Info=True;User ID=USERNAME;Data Source=REMOTE_IP_ADDRESS;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;Tag with column collation when possible=False;Initial Catalog=DATABASE"

    'Opens connection to the database
    cnn.Open ConnectionString
    'Timeout error in seconds for executing the entire query; this will run for 15 minutes before VBA timesout, but your database might timeout before this value
    cnn.CommandTimeout = 900

    'This is your actual MS SQL query that you need to run; you should check this query first using a more robust SQL editor (such as HeidiSQL) to ensure your query is valid
    StrQuery = "SELECT TOP 10 * FROM tbl_table"

    'Performs the actual query
    rst.Open StrQuery, cnn
    'Dumps all the results from the StrQuery into cell A2 of the first sheet in the active workbook
    Sheets(1).Range("A2").CopyFromRecordset rst
End Sub

Using jQuery's ajax method to retrieve images as a blob

You can't do this with jQuery ajax, but with native XMLHttpRequest.

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function(){
    if (this.readyState == 4 && this.status == 200){
        //this.response is what you're looking for
        handler(this.response);
        console.log(this.response, typeof this.response);
        var img = document.getElementById('img');
        var url = window.URL || window.webkitURL;
        img.src = url.createObjectURL(this.response);
    }
}
xhr.open('GET', 'http://jsfiddle.net/img/logo.png');
xhr.responseType = 'blob';
xhr.send();      

EDIT

So revisiting this topic, it seems it is indeed possible to do this with jQuery 3

_x000D_
_x000D_
jQuery.ajax({_x000D_
        url:'https://images.unsplash.com/photo-1465101108990-e5eac17cf76d?ixlib=rb-0.3.5&q=85&fm=jpg&crop=entropy&cs=srgb&ixid=eyJhcHBfaWQiOjE0NTg5fQ%3D%3D&s=471ae675a6140db97fea32b55781479e',_x000D_
        cache:false,_x000D_
        xhr:function(){// Seems like the only way to get access to the xhr object_x000D_
            var xhr = new XMLHttpRequest();_x000D_
            xhr.responseType= 'blob'_x000D_
            return xhr;_x000D_
        },_x000D_
        success: function(data){_x000D_
            var img = document.getElementById('img');_x000D_
            var url = window.URL || window.webkitURL;_x000D_
            img.src = url.createObjectURL(data);_x000D_
        },_x000D_
        error:function(){_x000D_
            _x000D_
        }_x000D_
    });
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.0.0/jquery.min.js"></script>_x000D_
<img id="img" width=100%>
_x000D_
_x000D_
_x000D_

or

use xhrFields to set the responseType

_x000D_
_x000D_
    jQuery.ajax({_x000D_
            url:'https://images.unsplash.com/photo-1465101108990-e5eac17cf76d?ixlib=rb-0.3.5&q=85&fm=jpg&crop=entropy&cs=srgb&ixid=eyJhcHBfaWQiOjE0NTg5fQ%3D%3D&s=471ae675a6140db97fea32b55781479e',_x000D_
            cache:false,_x000D_
            xhrFields:{_x000D_
                responseType: 'blob'_x000D_
            },_x000D_
            success: function(data){_x000D_
                var img = document.getElementById('img');_x000D_
                var url = window.URL || window.webkitURL;_x000D_
                img.src = url.createObjectURL(data);_x000D_
            },_x000D_
            error:function(){_x000D_
                _x000D_
            }_x000D_
        });
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.0.0/jquery.min.js"></script>_x000D_
    <img id="img" width=100%>
_x000D_
_x000D_
_x000D_

Attaching click to anchor tag in angular

<a href="#" (click)="onGoToPage2()">Go to page 2</a>

Git reset single file in feature branch to be the same as in master

you are almost there; you just need to give the reference to master; since you want to get the file from the master branch:

git checkout master -- filename

Note that the differences will be cached; so if you want to see the differences you obtained; use

git diff --cached

PHP reindex array?

$myarray = array_values($myarray);

array_values

Javascript Date Validation ( DD/MM/YYYY) & Age Checking

To get the values use pattern.exec() instead of pattern.test() (the .test() returns a boolean value).

How can I avoid getting this MySQL error Incorrect column specifier for column COLUMN NAME?

To use AUTO_INCREMENT you need to deifne column as INT or floating-point types, not CHAR.

AUTO_INCREMENT use only unsigned value, so it's good to use UNSIGNED as well;

CREATE TABLE discussion_topics (

     topic_id INT NOT NULL unsigned AUTO_INCREMENT,
     project_id char(36) NOT NULL,
     topic_subject VARCHAR(255) NOT NULL,
     topic_content TEXT default NULL,
     date_created DATETIME NOT NULL,
     date_last_post DATETIME NOT NULL,
     created_by_user_id char(36) NOT NULL,
     last_post_user_id char(36) NOT NULL,
     posts_count char(36) default NULL,
     PRIMARY KEY (topic_id) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;

Convert dateTime to ISO format yyyy-mm-dd hh:mm:ss in C#

date.ToString("o") // The Round-trip ("O", "o") Format Specifier
date.ToString("s") // The Sortable ("s") Format Specifier, conforming to ISO86801

MSDN Standard Date and Time Format Strings

How should I tackle --secure-file-priv in MySQL?

For MacOS Mojave running MySQL 5.6.23 I had this problem with writing files, but not loading them. (Not seen with previous versions of Mac OS). As most of the answers to this question have been for other systems, I thought I would post the my.cnf file that cured this (and a socket problems too) in case it is of help to other Mac users. This is /etc/my.cnf

[client]
default-character-set=utf8

[mysqld]
character-set-server=utf8
secure-file-priv = ""
skip-external-locking

(The internationalization is irrelevant to the question.)

Nothing else required. Just turn the MySQL server off and then on again in Preferences (we are talking Mac) for this to take.

How to pass a null variable to a SQL Stored Procedure from C#.net code

    SQLParam = cmd.Parameters.Add("@RetailerID", SqlDbType.Int, 4)
    If p_RetailerID.Length = 0 Or p_RetailerID = "0" Then
        SQLParam.Value = DBNull.Value
    Else
        SQLParam.Value = p_RetailerID
    End If

How to delete a workspace in Eclipse?

Just go to the \eclipse-java-helios-SR2-win32\eclipse\configuration.settings directory and change or remove org.eclipse.ui.ide.prefs file.

How can I make Flexbox children 100% height of their parent?

I suppose that Chrome's behavior is more consistent with the CSS specification (though it's less intuitive). According to Flexbox specification, the default stretch value of align-self property changes only the used value of the element's "cross size property" (height, in this case). And, as I understand the CSS 2.1 specification, the percentage heights are calculated from the specified value of the parent's height, not its used value. The specified value of the parent's height isn't affected by any flex properties and is still auto.

Setting an explicit height: 100% makes it formally possible to calculate the percentage height of the child, just like setting height: 100% to html makes it possible to calculate the percentage height of body in CSS 2.1.

PHP Swift mailer: Failed to authenticate on SMTP using 2 possible authenticators

If you are trying to send mail from your local enviroment eg. XAMPP or WAMP, this error will occur everytime, go ahead and try the same code on your web hosting or whatever you are using for production.

Also, 2 step authentication from google may be the issue.

Android: Expand/collapse animation

This was my solution, my ImageView grows from 100% to 200% and return to his original size, using two animation files inside res/anim/ folder

anim_grow.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="1.0"
  android:toXScale="2.0"
  android:fromYScale="1.0"
  android:toYScale="2.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

anim_shrink.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
 android:interpolator="@android:anim/accelerate_interpolator">
 <scale
  android:fromXScale="2.0"
  android:toXScale="1.0"
  android:fromYScale="2.0"
  android:toYScale="1.0"
  android:duration="3000"
  android:pivotX="50%"
  android:pivotY="50%"
  android:startOffset="2000" />
</set>

Send an ImageView to my method setAnimationGrowShrink()

ImageView img1 = (ImageView)findViewById(R.id.image1);
setAnimationGrowShrink(img1);

setAnimationGrowShrink() method:

private void setAnimationGrowShrink(final ImageView imgV){
    final Animation animationEnlarge = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_grow);
    final Animation animationShrink = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.anim_shrink);

    imgV.startAnimation(animationEnlarge);

    animationEnlarge.setAnimationListener(new AnimationListener() {         
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationShrink);
        }
    });

    animationShrink.setAnimationListener(new AnimationListener() {          
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {
            imgV.startAnimation(animationEnlarge);
        }
    });

}

List of all index & index columns in SQL Server DB

The query below includes all of the pertinent information for the user-defined indexes, (no indexes for unique constraints & primary keys) with all columns:

SELECT I.name as IndexName, 
        CASE WHEN I.is_unique = 1 THEN 'Yes' ELSE 'No' END as 'Unique',
        I.type_desc COLLATE DATABASE_DEFAULT as Index_Type,
        '[' + SCHEMA_NAME(T.schema_id) + ']' as 'Schema',
        '[' + T.name + ']' as TableName,
        STUFF((SELECT ', [' + C.name + CASE WHEN IC.is_descending_key = 0 THEN '] ASC' ELSE '] DESC' END
            FROM sys.index_columns IC INNER JOIN sys.columns C ON  IC.object_id = C.object_id  AND IC.column_id = C.column_id
            WHERE IC.is_included_column = 0 AND IC.object_id = I.object_id AND IC.index_id = I.Index_id
            FOR XML PATH('')), 1, 2, '') as Key_Columns,
        Included_Columns, 
        I.filter_definition,
        CASE WHEN I.is_padded = 1 THEN 'ON' ELSE 'OFF' END as PAD_INDEX, 
        CASE WHEN ST.no_recompute = 0 THEN 'OFF' ELSE 'ON' END as [Statistics_Norecompute],
        CONVERT(VARCHAR(5), CASE WHEN I.fill_factor = 0 THEN 100 ELSE I.fill_factor END) as [Fillfactor],
        CASE WHEN I.ignore_dup_key = 1 THEN 'ON' ELSE 'OFF' END as [Ignore_Dup_Key],       
        CASE WHEN I.allow_row_locks = 1 THEN 'ON' ELSE 'OFF' END as [Allow_Row_Locks], 
        CASE WHEN I.allow_page_locks = 1 THEN 'ON' ELSE 'OFF' END [Allow_Page_Locks]        
FROM    sys.indexes I INNER JOIN        
        sys.tables T ON  T.object_id = I.object_id INNER JOIN       
        sys.stats ST ON  ST.object_id = I.object_id AND ST.stats_id = I.index_id INNER JOIN 
        sys.data_spaces DS ON  I.data_space_id = DS.data_space_id INNER JOIN 
        sys.filegroups FG ON  I.data_space_id = FG.data_space_id LEFT OUTER JOIN 
        (SELECT * FROM 
            (SELECT IC2.object_id, IC2.index_id,
                STUFF((SELECT ', ' + C.name FROM sys.index_columns IC1 INNER JOIN 
                    sys.columns C ON C.object_id = IC1.object_id
                        AND C.column_id = IC1.column_id
                        AND IC1.is_included_column = 1
                    WHERE  IC1.object_id = IC2.object_id AND IC1.index_id = IC2.index_id
                    GROUP BY IC1.object_id, C.name, index_id  FOR XML PATH('')
                ), 1, 2, '') as Included_Columns
            FROM sys.index_columns IC2
            GROUP BY IC2.object_id, IC2.index_id) tmp1
            WHERE Included_Columns IS NOT NULL
        ) tmp2
        ON tmp2.object_id = I.object_id AND tmp2.index_id = I.index_id
WHERE I.is_primary_key = 0 AND I.is_unique_constraint = 0;

As an added bonus, the below query is formatted to write out the create index and drop index scripts:

SELECT I.name as IndexName, 
        -- Uncommnent line below to include checking for index exists as part of the script
        --'IF NOT EXISTS (SELECT name FROM sysindexes WHERE name = '''+ I.name +''') ' +
        'CREATE ' + CASE WHEN I.is_unique = 1 THEN ' UNIQUE ' ELSE '' END +
        I.type_desc COLLATE DATABASE_DEFAULT + ' INDEX [' +
        I.name + '] ON [' + SCHEMA_NAME(T.schema_id) + '].[' + T.name + '] (' + STUFF(
        (SELECT ', [' + C.name + CASE WHEN IC.is_descending_key = 0 THEN '] ASC' ELSE '] DESC' END
            FROM sys.index_columns IC INNER JOIN sys.columns C ON  IC.object_id = C.object_id  AND IC.column_id = C.column_id
            WHERE IC.is_included_column = 0 AND IC.object_id = I.object_id AND IC.index_id = I.Index_id
            FOR XML PATH('')), 1, 2, '')  + ') ' +
        ISNULL(' INCLUDE (' + IncludedColumns + ') ', '') +
        ISNULL(' WHERE ' + I.filter_definition, '') + 
        'WITH (PAD_INDEX = ' + CASE WHEN I.is_padded = 1 THEN 'ON' ELSE 'OFF' END + 
        ', STATISTICS_NORECOMPUTE = ' + CASE WHEN ST.no_recompute = 0 THEN 'OFF' ELSE 'ON' END + 
        ', SORT_IN_TEMPDB = OFF' + 
        ', FILLFACTOR = ' + CONVERT(VARCHAR(5), CASE WHEN I.fill_factor = 0 THEN 100 ELSE I.fill_factor END) +
        ', IGNORE_DUP_KEY = ' + CASE WHEN I.ignore_dup_key = 1 THEN 'ON' ELSE 'OFF' END +      
        ', ONLINE = OFF' + 
        ', ALLOW_ROW_LOCKS = ' + CASE WHEN I.allow_row_locks = 1 THEN 'ON' ELSE 'OFF' END + 
        ', ALLOW_PAGE_LOCKS = ' + CASE WHEN I.allow_page_locks = 1 THEN 'ON' ELSE 'OFF' END + 
        ') ON [' + DS.name + '];' + CHAR(13) + CHAR(10) + 'GO' as [CreateIndex],
        'DROP INDEX ['+ I.name +'] ON ['+ SCHEMA_NAME(T.schema_id) +'].['+ T.name +'];' +
        CHAR(13) + CHAR(10) + 'GO' AS [DropIndex]
FROM    sys.indexes I INNER JOIN        
        sys.tables T ON  T.object_id = I.object_id INNER JOIN       
        sys.stats ST ON  ST.object_id = I.object_id AND ST.stats_id = I.index_id INNER JOIN 
        sys.data_spaces DS ON  I.data_space_id = DS.data_space_id INNER JOIN 
        sys.filegroups FG ON  I.data_space_id = FG.data_space_id LEFT OUTER JOIN 
        (SELECT * FROM 
            (SELECT IC2.object_id, IC2.index_id,
                STUFF((SELECT ', ' + C.name FROM sys.index_columns IC1 INNER JOIN 
                    sys.columns C ON C.object_id = IC1.object_id
                        AND C.column_id = IC1.column_id
                        AND IC1.is_included_column = 1
                    WHERE  IC1.object_id = IC2.object_id AND IC1.index_id = IC2.index_id
                    GROUP BY IC1.object_id, C.name, index_id  FOR XML PATH('')
                ), 1, 2, '') as IncludedColumns
            FROM sys.index_columns IC2
            GROUP BY IC2.object_id, IC2.index_id) tmp1
            WHERE IncludedColumns IS NOT NULL
        ) tmp2
        ON tmp2.object_id = I.object_id AND tmp2.index_id = I.index_id
WHERE I.is_primary_key = 0 AND I.is_unique_constraint = 0 

How to clamp an integer to some range?

Whatever happened to my beloved readable Python language? :-)

Seriously, just make it a function:

def addInRange(val, add, minval, maxval):
    newval = val + add
    if newval < minval: return minval
    if newval > maxval: return maxval
    return newval

then just call it with something like:

val = addInRange(val, 7, 0, 42)

Or a simpler, more flexible, solution where you do the calculation yourself:

def restrict(val, minval, maxval):
    if val < minval: return minval
    if val > maxval: return maxval
    return val

x = restrict(x+10, 0, 42)

If you wanted to, you could even make the min/max a list so it looks more "mathematically pure":

x = restrict(val+7, [0, 42])

AutoComplete TextBox in WPF

I have published a WPF Auto Complete Text Box in WPF at CodePlex.com. You can download and try it from https://wpfautocomplete.codeplex.com/.

Git: How to check if a local repo is up to date?

You'll need to issue two commands:

  1. git fetch origin
  2. git status

Pandas read_csv low_memory and dtype options

Try:

dashboard_df = pd.read_csv(p_file, sep=',', error_bad_lines=False, index_col=False, dtype='unicode')

According to the pandas documentation:

dtype : Type name or dict of column -> type

As for low_memory, it's True by default and isn't yet documented. I don't think its relevant though. The error message is generic, so you shouldn't need to mess with low_memory anyway. Hope this helps and let me know if you have further problems

How do you find all subclasses of a given class in Java?

This is not possible to do using only the built-in Java Reflections API.

A project exists that does the necessary scanning and indexing of your classpath so you can get access this information...

Reflections

A Java runtime metadata analysis, in the spirit of Scannotations

Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project.

Using Reflections you can query your metadata for:

  • get all subtypes of some type
  • get all types annotated with some annotation
  • get all types annotated with some annotation, including annotation parameters matching
  • get all methods annotated with some

(disclaimer: I have not used it, but the project's description seems to be an exact fit for your needs.)

How to make a <svg> element expand or contract to its parent container?

@robertc has it right, but you also need to notice that svg, #container causes the svg to be scaled exponentially for anything but 100% (once for #container and once for svg).

In other words, if I applied 50% h/w to both elements, it's actually 50% of 50%, or .5 * .5, which equals .25, or 25% scale.

One selector works fine when used as @robertc suggests.

svg {
  width:50%;
  height:50%;
}

How to check if type is Boolean

BENCHMARKING:

All pretty similar...

const { performance } = require('perf_hooks');

const boolyah = true;
var t0 = 0;
var t1 = 0;
const loops = 1000000;
var results = { 1: 0, 2: 0, 3: 0, 4: 0 };

for (i = 0; i < loops; i++) {

    t0 = performance.now();
    boolyah === false || boolyah === true;
    t1 = performance.now();
    results['1'] += t1 - t0;

    t0 = performance.now();
    'boolean' === typeof boolyah;
    t1 = performance.now();
    results['2'] += t1 - t0;

    t0 = performance.now();
    !!boolyah === boolyah;
    t1 = performance.now();
    results['3'] += t1 - t0;

    t0 = performance.now();
    Boolean(boolyah) === boolyah;
    t1 = performance.now();
    results['4'] += t1 - t0;
}

console.log(results);

  // RESULTS
  // '0': 135.09559339284897,
  // '1': 136.38034391403198,
  // '2': 136.29421120882034,
  // '3': 135.1228678226471,
  // '4': 135.11531442403793

CSS background image in :after element

As AlienWebGuy said, you can use background-image. I'd suggest you use background, but it will need three more properties after the URL:

background: url("http://www.gentleface.com/i/free_toolbar_icons_16x16_black.png") 0 0 no-repeat;

Explanation: the two zeros are x and y positioning for the image; if you want to adjust where the background image displays, play around with these (you can use both positive and negative values, e.g: 1px or -1px).

No-repeat says you don't want the image to repeat across the entire background. This can also be repeat-x and repeat-y.

How to clear browser cache with php?

You can delete the browser cache by setting these headers:

<?php
header("Expires: Tue, 01 Jan 2000 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
?>

addEventListener vs onclick

According to MDN, the difference is as below:

addEventListener:

The EventTarget.addEventListener() method adds the specified EventListener-compatible object to the list of event listeners for the specified event type on the EventTarget on which it's called. The event target may be an Element in a document, the Document itself, a Window, or any other object that supports events (such as XMLHttpRequest).

onclick:

The onclick property returns the click event handler code on the current element. When using the click event to trigger an action, also consider adding this same action to the keydown event, to allow the use of that same action by people who don't use a mouse or a touch screen. Syntax element.onclick = functionRef; where functionRef is a function - often a name of a function declared elsewhere or a function expression. See "JavaScript Guide:Functions" for details.

There is also a syntax difference in use as you see in the below codes:

addEventListener:

// Function to change the content of t2
function modifyText() {
  var t2 = document.getElementById("t2");
  if (t2.firstChild.nodeValue == "three") {
    t2.firstChild.nodeValue = "two";
  } else {
    t2.firstChild.nodeValue = "three";
  }
}

// add event listener to table
var el = document.getElementById("outside");
el.addEventListener("click", modifyText, false);

onclick:

function initElement() {
    var p = document.getElementById("foo");
    // NOTE: showAlert(); or showAlert(param); will NOT work here.
    // Must be a reference to a function name, not a function call.
    p.onclick = showAlert;
};

function showAlert(event) {
    alert("onclick Event detected!");
}

Can I use jQuery with Node.js?

As of jsdom v10, .env() function is deprecated. I did it like below after trying a lot of things to require jquery:

_x000D_
_x000D_
var jsdom = require('jsdom');_x000D_
const { JSDOM } = jsdom;_x000D_
const { window } = new JSDOM();_x000D_
const { document } = (new JSDOM('')).window;_x000D_
global.document = document;_x000D_
_x000D_
var $ = jQuery = require('jquery')(window);
_x000D_
_x000D_
_x000D_

Hope this helps you or anyone who has been facing these types of issues.

OS X Terminal Colors

If you want to have your ls colorized you have to edit your ~/.bash_profile file and add the following line (if not already written) :

source .bashrc

Then you edit or create ~/.bashrc file and write an alias to the ls command :

alias ls="ls -G"

Now you have to type source .bashrc in a terminal if already launched, or simply open a new terminal.

If you want more options in your ls juste read the manual ( man ls ). Options are not exactly the same as in a GNU/Linux system.

Proxy with urllib2

You can set proxies using environment variables.

import os
os.environ['http_proxy'] = '127.0.0.1'
os.environ['https_proxy'] = '127.0.0.1'

urllib2 will add proxy handlers automatically this way. You need to set proxies for different protocols separately otherwise they will fail (in terms of not going through proxy), see below.

For example:

proxy = urllib2.ProxyHandler({'http': '127.0.0.1'})
opener = urllib2.build_opener(proxy)
urllib2.install_opener(opener)
urllib2.urlopen('http://www.google.com')
# next line will fail (will not go through the proxy) (https)
urllib2.urlopen('https://www.google.com')

Instead

proxy = urllib2.ProxyHandler({
    'http': '127.0.0.1',
    'https': '127.0.0.1'
})
opener = urllib2.build_opener(proxy)
urllib2.install_opener(opener)
# this way both http and https requests go through the proxy
urllib2.urlopen('http://www.google.com')
urllib2.urlopen('https://www.google.com')

How to make an installer for my C# application?

There are several methods, two of which are as follows. Provide a custom installer or a setup project.

Here is how to create a custom installer

[RunInstaller(true)]
public class MyInstaller : Installer
{
    public HelloInstaller()
        : base()
    {
    }

    public override void Commit(IDictionary mySavedState)
    {
        base.Commit(mySavedState);
        System.IO.File.CreateText("Commit.txt");
    }

    public override void Install(IDictionary stateSaver)
    {
        base.Install(stateSaver);
        System.IO.File.CreateText("Install.txt");
    }

    public override void Uninstall(IDictionary savedState)
    {
        base.Uninstall(savedState);
        File.Delete("Commit.txt");
        File.Delete("Install.txt");
    }

    public override void Rollback(IDictionary savedState)
    {
        base.Rollback(savedState);
        File.Delete("Install.txt");
    }
}

To add a setup project

  • Menu file -> New -> Project --> Other Projects Types --> Setup and Deployment

  • Set properties of the project, using the properties window

The article How to create a Setup package by using Visual Studio .NET provides the details.

Parse date string and change format

convert string to datetime object

from datetime import datetime
s = "2016-03-26T09:25:55.000Z"
f = "%Y-%m-%dT%H:%M:%S.%fZ"
out = datetime.strptime(s, f)
print(out)
output:
2016-03-26 09:25:55

Convert HTML to PDF in .NET

EDIT: New Suggestion HTML Renderer for PDF using PdfSharp

(After trying wkhtmltopdf and suggesting to avoid it)

HtmlRenderer.PdfSharp is a 100% fully C# managed code, easy to use, thread safe and most importantly FREE (New BSD License) solution.

Usage

  1. Download HtmlRenderer.PdfSharp nuget package.
  2. Use Example Method.

    public static Byte[] PdfSharpConvert(String html)
    {
        Byte[] res = null;
        using (MemoryStream ms = new MemoryStream())
        {
            var pdf = TheArtOfDev.HtmlRenderer.PdfSharp.PdfGenerator.GeneratePdf(html, PdfSharp.PageSize.A4);
            pdf.Save(ms);
            res = ms.ToArray();
        }
        return res;
    }
    

A very Good Alternate Is a Free Version of iTextSharp

Until version 4.1.6 iTextSharp was licensed under the LGPL licence and versions until 4.16 (or there may be also forks) are available as packages and can be freely used. Of course someone can use the continued 5+ paid version.

I tried to integrate wkhtmltopdf solutions on my project and had a bunch of hurdles.

I personally would avoid using wkhtmltopdf - based solutions on Hosted Enterprise applications for the following reasons.

  1. First of all wkhtmltopdf is C++ implemented not C#, and you will experience various problems embedding it within your C# code, especially while switching between 32bit and 64bit builds of your project. Had to try several workarounds including conditional project building etc. etc. just to avoid "invalid format exceptions" on different machines.
  2. If you manage your own virtual machine its ok. But if your project is running within a constrained environment like (Azure (Actually is impossible withing azure as mentioned by the TuesPenchin author) , Elastic Beanstalk etc) it's a nightmare to configure that environment only for wkhtmltopdf to work.
  3. wkhtmltopdf is creating files within your server so you have to manage user permissions and grant "write" access to where wkhtmltopdf is running.
  4. Wkhtmltopdf is running as a standalone application, so its not managed by your IIS application pool. So you have to either host it as a service on another machine or you will experience processing spikes and memory consumption within your production server.
  5. It uses temp files to generate the pdf, and in cases Like AWS EC2 which has really slow disk i/o it is a big performance problem.
  6. The most hated "Unable to load DLL 'wkhtmltox.dll'" error reported by many users.

--- PRE Edit Section ---

For anyone who want to generate pdf from html in simpler applications / environments I leave my old post as suggestion.

TuesPechkin

https://www.nuget.org/packages/TuesPechkin/

or Especially For MVC Web Applications (But I think you may use it in any .net application)

Rotativa

https://www.nuget.org/packages/Rotativa/

They both utilize the wkhtmtopdf binary for converting html to pdf. Which uses the webkit engine for rendering the pages so it can also parse css style sheets.

They provide easy to use seamless integration with C#.

Rotativa can also generate directly PDFs from any Razor View.

Additionally for real world web applications they also manage thread safety etc...

Why would a "java.net.ConnectException: Connection timed out" exception occur when URL is up?

Connection timeouts (assuming a local network and several client machines) typically result from

a) some kind of firewall on the way that simply eats the packets without telling the sender things like "No Route to host"

b) packet loss due to wrong network configuration or line overload

c) too many requests overloading the server

d) a small number of simultaneously available threads/processes on the server which leads to all of them being taken. This happens especially with requests that take a long time to run and may combine with c).

Hope this helps.

Simple JavaScript login form validation

<!DOCTYPE html>
<html>
<head>
<script>
function vali() {
var u=document.forms["myform"]["user"].value;
var p=document.forms["myform"]["pwd"].value;
if(u == p) {
alert("Welcome");
window.location="sec.html";
return false;
}
else
{
alert("Please Try again!");
return false;
}
}
</script>
</head>
<body>
<form method="post">
<fieldset style="width:35px;">  <legend>Login Here</legend>
<input type="text" name="user" placeholder="Username" required>
<br>
<input type="Password" name="pwd" placeholder="Password" required>
<br>
<input type="submit" name="submit" value="submit" onclick="return vali()">
</form>
</fieldset>
</html>

C++ "was not declared in this scope" compile error

What's wrong:

The definition of "nonrecursivecountcells" has no parameter named grid. You need to pass the type AND variable name to the function. You only passed the type.

Note if you use the name grid for the parameter, that name has nothing to do with your main() declaration of grid. You could have used any other name as well.

***Also you can't pass arrays as values.


How to fix:

The easy way to fix this is to pass a pointer to an array to the function "nonrecursivecountcells".

int nonrecursivecountcells(color[ROW_SIZE][COL_SIZE], int, int);

better and type safe ->

int nonrecursivecountcells(color (&grid)[ROW_SIZE][COL_SIZE], int, int);

About scope:

A variable created on the stack comes out of scope when the block it is declared in is terminated. A block is anything within an opening and matching closing brace. For example an if() { }, function() { }, while() {}, ...

Note I said variable and not data. For example you can allocate memory on the heap and that data will still remain valid even outside of the scope. But the variable that originally pointed to it would still come out of scope.

yii2 redirect in controller action does not work?

Redirects the browser to the specified URL.

This method adds a "Location" header to the current response. Note that it does not send out the header until send() is called. In a controller action you may use this method as follows:

return Yii::$app->getResponse()->redirect($url);

In other places, if you want to send out the "Location" header immediately, you should use the following code:

Yii::$app->getResponse()->redirect($url)->send();
return;

Calculate last day of month in JavaScript

My colleague stumbled upon the following which may be an easier solution

function daysInMonth(iMonth, iYear)
{
    return 32 - new Date(iYear, iMonth, 32).getDate();
}

stolen from http://snippets.dzone.com/posts/show/2099

Is it possible to have empty RequestParam values use the defaultValue?

This was considered a bug in 2013: https://jira.spring.io/browse/SPR-10180

and was fixed with version 3.2.2. Problem shouldn't occur in any versions after that and your code should work just fine.

How do I add multiple conditions to "ng-disabled"?

this way worked for me

ng-disabled="(user.Role.ID != 1) && (user.Role.ID != 2)"

"The operation is not valid for the state of the transaction" error and transaction scope

For me, this error came up when I was trying to rollback a transaction block after encountering an exception, inside another transaction block.

All I had to do to fix it was to remove my inner transaction block.

Things can get quite messy when using nested transactions, best to avoid this and just restructure your code.

How to automatically update an application without ClickOnce?

A Lay men's way is

on Main() rename the executing assembly file .exe to some thing else check date and time of created. and the updated file date time and copy to the application folder.

//Rename he executing file
System.IO.FileInfo file = new System.IO.FileInfo(System.Reflection.Assembly.GetExecutingAssembly().Location);

System.IO.File.Move(file.FullName, file.DirectoryName + "\\" + file.Name.Replace(file.Extension,"") + "-1" + file.Extension);

then do the logic check and copy the new file to executing folder

SQL Server: Importing database from .mdf?

Apart from steps mentioned in posted answers by @daniele3004 above, I had to open SSMS as Administrator otherwise it was showing Primary file is read only error.

Go to Start Menu , navigate to SSMS link , right click on the SSMS link , select Run As Administrator. Then perform the above steps.

Boolean checking in the 'if' condition

My personal feeling when it comes to reading

if(!status) : if not status

if(status == false) : if status is false

if you are not used to !status reading. I see no harm doing as the second way.

if you use "active" instead of status I thing if(!active) is more readable

shorthand c++ if else statement

Yes:

bigInt.sign = !(number < 0);

The ! operator always evaluates to true or false. When converted to int, these become 1 and 0 respectively.

Of course this is equivalent to:

bigInt.sign = (number >= 0);

Here the parentheses are redundant but I add them for clarity. All of the comparison and relational operator evaluate to true or false.

Last segment of URL in jquery

To get the last segment of your current window:

window.location.href.substr(window.location.href.lastIndexOf('/') +1)

How to automate browsing using python?

There are plenty of built in python modules that whould help with this. For example urllib and htmllib.

The problem will be simpler if you change the way you're approaching it. You say you want to "fill some forms, click submit button, send the data back to server, recieve the response", which sounds like a four stage process.

In fact, what you need to do is post some data to a webserver and get a response.

This is as simple as:

>>> import urllib
>>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
>>> f = urllib.urlopen("http://www.musi-cal.com/cgi-bin/query", params)
>>> print f.read()

(example taken from the urllib docs).

What you do with the response depends on how complex the HTML is and what you want to do with it. You might get away with parsing it using a regular expression or two, or you can use the htmllib.HTMLParser class, or maybe a higher level more flexible parser like Beautiful Soup.

writing to serial port from linux command line

echo '\x12\x02'

will not be interpreted, and will literally write the string \x12\x02 (and append a newline) to the specified serial port. Instead use

echo -n ^R^B

which you can construct on the command line by typing CtrlVCtrlR and CtrlVCtrlB. Or it is easier to use an editor to type into a script file.

The stty command should work, unless another program is interfering. A common culprit is gpsd which looks for GPS devices being plugged in.

"This project is incompatible with the current version of Visual Studio"

This issue might be caused when using VS 2015 with Update 3 installed on one PC and without update 3 installed on another. This was the problem in my case.

CURL ERROR: Recv failure: Connection reset by peer - PHP Curl

So what is the URL that Yii::app()->params['pdfUrl'] gives? You say it should be https, but the log shows it's connecting on port 80... which almost no server is setup to accept https connections on. cURL is smart enough to know https should be on port 443... which would suggest that your URL has something wonky in it like: https://196.41.139.168:80/serve/?r=pdf/generatePdf

That's going to cause the connection to be terminated, when the Apache at the other end cannot do https communication with you on that port.

You realize your first $body definition gets replaced when you set $body to an array two lines later? {Probably just an artifact of you trying to solve the problem} You're also not encoding the client_url and client_id values (the former quite possibly containing characters that need escaping!) Oh and you're appending to $body_str without first initializing it.

From your verbose output we can see cURL is adding a content-length header, but... is it correct? I can see some comments out on the internets of that number being wrong (especially with older versions)... if that number was to small (for example) you'd get a connection-reset before all the data is sent. You can manually insert the header:

curl_setopt ($c, CURLOPT_HTTPHEADER, 
   array("Content-Length: ". strlen($body_str))); 

Oh and there's a handy function http_build_query that'll convert an array of name/value pairs into a URL encoded string for you.

All this rolls up into the final code:

$post=http_build_query(array(
  "client_url"=>Yii::app()->params['pdfClientURL'],
  "client_id"=>Yii::app()->params['pdfClientID'],
  "title"=>$title,
  "content"=>$content));

//Open to URL
$c=curl_init(Yii::app()->params['pdfUrl']);
//Send post
curl_setopt ($c, CURLOPT_POST, true);
//Optional: [try with/without]
curl_setopt ($c, CURLOPT_HTTPHEADER, array("Content-Length: ".strlen($post))); 
curl_setopt ($c, CURLOPT_POSTFIELDS, $post);
curl_setopt ($c, CURLOPT_RETURNTRANSFER, true);
curl_setopt ($c, CURLOPT_CONNECTTIMEOUT , 0);
curl_setopt ($c, CURLOPT_TIMEOUT  , 20);
//Collect result
$pdf = curl_exec ($c);
$curlInfo = curl_getinfo($c);
curl_close($c);

T-sql - determine if value is integer

The following is correct for a WHERE clause; to make a function wrap it in CASE WHEN.

 ISNUMERIC(table.field) > 0 AND PATINDEX('%[^0123456789]%', table.field) = 0

How to convert milliseconds to seconds with precision

I had this problem too, somehow my code did not present the exact values but rounded the number in seconds to 0.0 (if milliseconds was under 1 second). What helped me out is adding the decimal to the division value.

double time_seconds = time_milliseconds / 1000.0;   // add the decimal
System.out.println(time_milliseconds);              // Now this should give you the right value.

List files recursively in Linux CLI with path relative to the current directory

That does the trick:

ls -R1 $PWD | while read l; do case $l in *:) d=${l%:};; "") d=;; *) echo "$d/$l";; esac; done | grep -i ".txt"

But it does that by "sinning" with the parsing of ls, though, which is considered bad form by the GNU and Ghostscript communities.

How to install PostgreSQL's pg gem on Ubuntu?

I'm on Ubuntu 12.10 and running this command:

apt-get install libpq-dev

helped me - after that ran gem install pg -v "0.14.1", and all good now

How to click a href link using Selenium

 webDriver.findElement(By.xpath("//a[@href='/docs/configuration']")).click();

The above line works fine. Please remove the space after href.

Is that element is visible in the page, if the element is not visible please scroll down the page then perform click action.

Python send POST with header

To make POST request instead of GET request using urllib2, you need to specify empty data, for example:

import urllib2
req = urllib2.Request("http://am.domain.com:8080/openam/json/realms/root/authenticate?authIndexType=Module&authIndexValue=LDAP")
req.add_header('X-OpenAM-Username', 'demo')
req.add_data('')
r = urllib2.urlopen(req)

Current date without time

Try this:

   var mydtn = DateTime.Today;
   var myDt = mydtn.Date;return myDt.ToString("d", CultureInfo.GetCultureInfo("en-US"));

SecurityException during executing jnlp file (Missing required Permissions manifest attribute in main jar)

JAR File Manifest Attributes for Security

The JAR file manifest contains information about the contents of the JAR file, including security and configuration information.

Add the attributes to the manifest before the JAR file is signed.
See Modifying a Manifest File in the Java Tutorial for information on adding attributes to the JAR manifest file.

Permissions Attribute

The Permissions attribute is used to verify that the permissions level requested by the RIA when it runs matches the permissions level that was set when the JAR file was created.

Use this attribute to help prevent someone from re-deploying an application that is signed with your certificate and running it at a different privilege level. Set this attribute to one of the following values:

  • sandbox - runs in the security sandbox and does not require additional permissions.

  • all-permissions - requires access to the user's system resources.

Changes to Security Slider:

The following changes to Security Slider were included in this release(7u51):

  • Block Self-Signed and Unsigned applets on High Security Setting
  • Require Permissions Attribute for High Security Setting
  • Warn users of missing Permissions Attributes for Medium Security Setting

For more information, see Java Control Panel documentation.

enter image description here

sample MANIFEST.MF

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.3
Created-By: 1.7.0_51-b13 (Oracle Corporation)
Trusted-Only: true
Class-Path: lib/plugin.jar
Permissions: sandbox
Codebase: http://myweb.de http://www.myweb.de
Application-Name: summary-applet

Get an array of list element contents in jQuery

var optionTexts = [];
$("ul li").each(function() { optionTexts.push($(this).text()) });

...should do the trick. To get the final output you're looking for, join() plus some concatenation will do nicely:

var quotedCSV = '"' + optionTexts.join('", "') + '"';

How do I print debug messages in the Google Chrome JavaScript Console?

Here's my console wrapper class. It gives me scope output as well to make life easier. Note the use of localConsole.debug.call() so that localConsole.debug runs in the scope of the calling class, providing access to its toString method.

localConsole = {

    info: function(caller, msg, args) {
        if ( window.console && window.console.info ) {
            var params = [(this.className) ? this.className : this.toString() + '.' + caller + '(), ' + msg];
            if (args) {
                params = params.concat(args);
            }
            console.info.apply(console, params);
        }
    },

    debug: function(caller, msg, args) {
        if ( window.console && window.console.debug ) {
            var params = [(this.className) ? this.className : this.toString() + '.' + caller + '(), ' + msg];
            if (args) {
                params = params.concat(args);
            }
            console.debug.apply(console, params);
        }
    }
};

someClass = {

    toString: function(){
        return 'In scope of someClass';
    },

    someFunc: function() {

        myObj = {
            dr: 'zeus',
            cat: 'hat'
        };

        localConsole.debug.call(this, 'someFunc', 'myObj: ', myObj);
    }
};

someClass.someFunc();

This gives output like so in Firebug:

In scope of someClass.someFunc(), myObj: Object { dr="zeus", more...}

Or Chrome:

In scope of someClass.someFunc(), obj:
Object
cat: "hat"
dr: "zeus"
__proto__: Object

Arithmetic operation resulted in an overflow. (Adding integers)

For simplicity I will use bytes:

byte a=250;
byte b=8;
byte c=a+b;

if a, b, and c were 'int', you would expect 258, but in the case of 'byte', the expected result would be 2 (258 & 0xFF), but in a Windows application you get an exception, in a console one you may not (I don't, but this may depend on IDE, I use SharpDevelop).

Sometimes, however, that behaviour is desired (e.g. you only care about the lower 8 bits of the result).

You could do the following:

byte a=250;
byte b=8;

byte c=(byte)((int)a + (int)b);

This way both 'a' and 'b' are converted to 'int', added, then casted back to 'byte'.

To be on the safe side, you may also want to try:

...
byte c=(byte)(((int)a + (int)b) & 0xFF);

Or if you really want that behaviour, the much simpler way of doing the above is:

unchecked
{
    byte a=250;
    byte b=8;
    byte c=a+b;
}

Or declare your variables first, then do the math in the 'unchecked' section.

Alternately, if you want to force the checking of overflow, use 'checked' instead.

Hope this clears things up.

Nurchi

P.S.

Trust me, that exception is your friend :)

printf and long double

Yes -- for long double, you need to use %Lf (i.e., upper-case 'L').

Print array elements on separate lines in Bash?

Try doing this :

$ printf '%s\n' "${my_array[@]}"

The difference between $@ and $*:

  • Unquoted, the results are unspecified. In Bash, both expand to separate args and then wordsplit and globbed.

  • Quoted, "$@" expands each element as a separate argument, while "$*" expands to the args merged into one argument: "$1c$2c..." (where c is the first char of IFS).

You almost always want "$@". Same goes for "${arr[@]}".

Always quote them!

Concatenate multiple files but include filename as section headers

I like this option

for x in $(ls ./*.php); do echo $x; cat $x | grep -i 'menuItem'; done

Output looks like this:

./debug-things.php
./Facebook.Pixel.Code.php
./footer.trusted.seller.items.php
./GoogleAnalytics.php
./JivositeCode.php
./Live-Messenger.php
./mPopex.php
./NOTIFICATIONS-box.php
./reviewPopUp_Frame.php
            $('#top-nav-scroller-pos-<?=$active**MenuItem**;?>').addClass('active');
            gotTo**MenuItem**();
./Reviews-Frames-PopUps.php
./social.media.login.btns.php
./social-side-bar.php
./staticWalletsAlerst.php
./tmp-fix.php
./top-nav-scroller.php
$active**MenuItem** = '0';
        $active**MenuItem** = '1';
        $active**MenuItem** = '2';
        $active**MenuItem** = '3';
./Waiting-Overlay.php
./Yandex.Metrika.php

How do I draw a circle in iOS Swift?

A simple function drawing a circle on the middle of your window frame, using a multiplicator percentage

/// CGFloat is a multiplicator from self.view.frame.width
func drawCircle(withMultiplicator coefficient: CGFloat) {

    let radius = self.view.frame.width / 2 * coefficient

    let circlePath = UIBezierPath(arcCenter: self.view.center, radius: radius, startAngle: CGFloat(0), endAngle:CGFloat(Double.pi * 2), clockwise: true)
    let shapeLayer = CAShapeLayer()
    shapeLayer.path = circlePath.cgPath

    //change the fill color
    shapeLayer.fillColor = UIColor.clear.cgColor
    shapeLayer.strokeColor = UIColor.darkGray.cgColor
    shapeLayer.lineWidth = 2.0

    view.layer.addSublayer(shapeLayer)
}

How to write a comment in a Razor view?

Note that in general, IDE's like Visual Studio will markup a comment in the context of the current language, by selecting the text you wish to turn into a comment, and then using the Ctrl+K Ctrl+C shortcut, or if you are using Resharper / Intelli-J style shortcuts, then Ctrl+/.

Server side Comments:

Razor .cshtml

Like so:

@* Comment goes here *@

.aspx
For those looking for the older .aspx view (and Asp.Net WebForms) server side comment syntax:

<%-- Comment goes here --%>

Client Side Comments

HTML Comment

<!-- Comment goes here -->

Javascript Comment

// One line Comment goes Here
/* Multiline comment
   goes here */

As OP mentions, although not displayed on the browser, client side comments will still be generated for the page / script file on the server and downloaded by the page over HTTP, which unless removed (e.g. minification), will waste I/O, and, since the comment can be viewed by the user by viewing the page source or intercepting the traffic with the browser's Dev Tools or a tool like Fiddler or Wireshark, can also pose a security risk, hence the preference to use server side comments on server generated code (like MVC views or .aspx pages).

SQL Plus change current directory

With Oracle's new SQLcl there is a cd command now and accompanying pwd. SQLcl can be downloaded here: http://www.oracle.com/technetwork/developer-tools/sqlcl/overview/index.html

Here's a quick example:

SQL>pwd
/Users/klrice/
NOT_SAFE>!ls *.sql
db_awr.sql  emp.sql     img.sql     jeff.sql    orclcode.sql    test.sql
db_info.sql fn.sql      iot.sql     login.sql   rmoug.sql

SQL>cd sql
SQL>!ls *.sql
003.sql             demo_worksheet_name.sql     poll_so_stats.sql
1.sql               dual.sql            print_updates.sql

SQL>

What is difference between Errors and Exceptions?

Error is something that most of the time you cannot handle it.

Exception was meant to give you an opportunity to do something with it. like try something else or write to the log.

try{
  //connect to database 1
}
catch(DatabaseConnctionException err){
  //connect to database 2
  //write the err to log
}

How to programmatically determine the current checked out Git branch

Same results as accepted answer in a one-line variable assignment:

branch_name=$((git symbolic-ref HEAD 2>/dev/null || echo "(unnamed branch)")|cut -d/ -f3-)

How to ping a server only once from within a batch file?

Just write the command "ping your server IP" without the double quote. save file name as filename.bat and then run the batch file as administrator

git commit error: pathspec 'commit' did not match any file(s) known to git

In my case, the problem was I used wrong alias for git commit -m. I used gcalias which dit not meant git commit -m

Parsing xml using powershell

First step is to load your xml string into an XmlDocument, using powershell's unique ability to cast strings to [xml]

$doc = [xml]@'
<xml>
    <Section name="BackendStatus">
        <BEName BE="crust" Status="1" />
        <BEName BE="pizza" Status="1" />
        <BEName BE="pie" Status="1" />
        <BEName BE="bread" Status="1" />
        <BEName BE="Kulcha" Status="1" />
        <BEName BE="kulfi" Status="1" />
        <BEName BE="cheese" Status="1" />
    </Section>
</xml>
'@

Powershell makes it really easy to parse xml with the dot notation. This statement will produce a sequence of XmlElements for your BEName elements:

$doc.xml.Section.BEName

Then you can pipe these objects into the where-object cmdlet to filter down the results. You can use ? as a shortcut for where

$doc.xml.Section.BEName | ? { $_.Status -eq 1 }

The expression inside the braces will be evaluated for each XmlElement in the pipeline, and only those that have a Status of 1 will be returned. The $_ operator refers to the current object in the pipeline (an XmlElement).

If you need to do something for every object in your pipeline, you can pipe the objects into the foreach-object cmdlet, which executes a block for every object in the pipeline. % is a shortcut for foreach:

$doc.xml.Section.BEName | ? { $_.Status -eq 1 } | % { $_.BE + " is delicious" }

Powershell is great at this stuff. It's really easy to assemble pipelines of objects, filter pipelines, and do operations on each object in the pipeline.

Adding quotes to a string in VBScript

You can escape by doubling the quotes

g="abcd """ & a & """"

or write an explicit chr() call

g="abcd " & chr(34) & a & chr(34)

pandas resample documentation

There's more to it than this, but you're probably looking for this list:

B   business day frequency
C   custom business day frequency (experimental)
D   calendar day frequency
W   weekly frequency
M   month end frequency
BM  business month end frequency
MS  month start frequency
BMS business month start frequency
Q   quarter end frequency
BQ  business quarter endfrequency
QS  quarter start frequency
BQS business quarter start frequency
A   year end frequency
BA  business year end frequency
AS  year start frequency
BAS business year start frequency
H   hourly frequency
T   minutely frequency
S   secondly frequency
L   milliseconds
U   microseconds

Source: http://pandas.pydata.org/pandas-docs/stable/timeseries.html#offset-aliases

How do I sort an NSMutableArray with custom objects in it?

  let sortedUsers = users.sorted {
    $0.firstName < $1.firstName
 }

What's the difference between ng-model and ng-bind

ngModel

The ngModel directive binds an input,select, textarea (or custom form control) to a property on the scope.

This directive executes at priority level 1.

Example Plunker

JAVASCRIPT

angular.module('inputExample', [])
   .controller('ExampleController', ['$scope', function($scope) {
     $scope.val = '1';
}]);

CSS

.my-input {
    -webkit-transition:all linear 0.5s;
    transition:all linear 0.5s;
    background: transparent;
}
.my-input.ng-invalid {
    color:white;
    background: red;
}

HTML

<p id="inputDescription">
   Update input to see transitions when valid/invalid.
   Integer is a valid value.
</p>
<form name="testForm" ng-controller="ExampleController">
    <input ng-model="val" ng-pattern="/^\d+$/" name="anim" class="my-input"
         aria-describedby="inputDescription" />
</form>

ngModel is responsible for:

  • Binding the view into the model, which other directives such as input, textarea or select require.
  • Providing validation behavior (i.e. required, number, email, url).
  • Keeping the state of the control (valid/invalid, dirty/pristine, touched/untouched, validation errors).
  • Setting related css classes on the element (ng-valid, ng-invalid, ng-dirty, ng-pristine, ng-touched, ng-untouched) including animations.
  • Registering the control with its parent form.

ngBind

The ngBind attribute tells Angular to replace the text content of the specified HTML element with the value of a given expression, and to update the text content when the value of that expression changes.

This directive executes at priority level 0.

Example Plunker

JAVASCRIPT

angular.module('bindExample', [])
    .controller('ExampleController', ['$scope', function($scope) {
    $scope.name = 'Whirled';
}]);

HTML

<div ng-controller="ExampleController">
  <label>Enter name: <input type="text" ng-model="name"></label><br>
  Hello <span ng-bind="name"></span>!
</div>

ngBind is responsible for:

  • Replacing the text content of the specified HTML element with the value of a given expression.

How can I use a search engine to search for special characters?

duckduckgo.com doesn't ignore special characters, at least if the whole string is between ""

https://duckduckgo.com/?q=%22*222%23%22

Matplotlib-Animation "No MovieWriters Available"

Had the same problem....managed to get it to work after a little while.

Thing to do is follow instructions on installing FFmpeg - which is (at least on windows) a bundle of executables you need to set a path to in your environment variables

http://www.wikihow.com/Install-FFmpeg-on-Windows

Download from ffmpeg.org

Hope this helps someone - even after a while after the question - good luck

Could not load file or assembly '' or one of its dependencies

My solution was:

I have a three-tier application and I forgot to copy the DLL also to the right path at IIS. Just after copied it to the right place it worked for me.

How to check sbt version?

run sbt console then type sbtVersion to check sbt version, and scalaVersion for scala version

Deserialize JSON array(or list) in C#

Download Json.NET from here http://james.newtonking.com/projects/json-net.aspx

name deserializedName = JsonConvert.DeserializeObject<name>(jsonData);

Angular 2 Unit Tests: Cannot find name 'describe'

Look at the import maybe you have a cycle dependency, this was in my case the error, using import {} from 'jasmine'; will fix the errors in the console and make the code compilable but not removes the root of devil (in my case the cycle dependency).

Should I use <i> tag for icons instead of <span>?

I'm jumping in here a little late, but came across this page when pondering it myself. Of course I don't know how Facebook or Twitter justified it, but here is my own thought process for what it's worth.

In the end, I concluded that this practice is not that unsemantic (is that a word?). In fact, besides shortness and the nice association of "i is for icon," I think it's actually the most semantic choice for an icon when a straightforward <img> tag is not practical.

1. The usage is consistent with the spec.

While it may not be what the W3 mainly had in mind, it seems to me the official spec for <i> could accommodate an icon pretty easily. After all, the reply-arrow symbol is saying "reply" in another way. It expresses a technical term that may be unfamiliar to the reader and would be typically italicized. ("Here at Twitter, this is what we call a reply arrow.") And it is a term from another language: a symbolic language.

If, instead of the arrow symbol, Twitter used <i>shout out</i> or <i>[Japanese character for reply]</i> (on an English page), that would be consistent with the spec. Then why not <i>[reply arrow]</i>? (I'm talking strictly HTML semantics here, not accessibility, which I'll get to.)

As far as I can see, the only part of the spec explicitly violated by icon usage is the "span of text" phrase (when the tag doesn't contain text also). It is clear that the <i> tag is mainly meant for text, but that's a pretty small detail compared with the overall intent of the tag. The important question for this tag is not what format of content it contains, but what the meaning of that content is.

This is especially true when you consider that the line between "text" and "icon" can be almost nonexistent on websites. Text may look like more like an icon (as in the Japanese example) or an icon may look like text (as in a jpg button that says "Submit" or a cat photo with an overlaid caption) or text may be replaced or enhanced with an image via CSS. Text, image - who cares? It's all content. As long as everyone - humans with impairments, browsers with impairments, search engine spiders, and other machines of various kinds can understand that meaning, we've done our job.

So the fact that the writers of the spec didn't think (or choose) to clarify this shouldn't tie our hands from doing what makes sense and is consistent with the spirit of the tag. The <a> tag was originally intended to take the user somewhere else, but now it might pop up a lightbox. Big whoop, right? If someone had figured out how to pop up a lightbox on click before the spec caught up, they still should have used the <a> tag, not a <span>, even if it wasn't entirely consistent with the current definition - because it came the closest and was still consistent with the spirit of the tag ("something will happen when you click here"). Same deal with <i> - whatever type of thing you put inside it, or however creatively you use it, it expresses the general idea of an alternate or set-apart term.

2. The <i> tag adds semantic meaning to an icon element.

The alternative option to carry an icon class by itself is <span>, which of course has no semantic meaning whatsoever. When a machine asks the <span> what it contains, it says, "I don't know. Could be anything." But the <i> tag says, "I contain a different way of saying something than the usual way, or maybe an unfamiliar term." That's not the same as "I contain an icon," but it's a lot closer to it than <span> got!

3. Eventually, common usage makes right.

In addition to the above, it's worth considering that machine readers (whether search engine, screen reader, or whatever) may at any time begin to take into account that Facebook, Twitter, and other websites use the <i> tag for icons. They don't care about the spec as much as they care about extracting meaning from code by whatever means necessary. So they might use this knowledge of common usage to simply record that "there may be an icon here" or do something more advanced like triggering a look into the CSS for a hint to meaning, or who knows what. So if you choose to use the <i> for icons on your website, you may be providing more meaning than the spec does.

Moreover, if this usage becomes widespread, it will likely be included in the spec in the future. Then you'll be going through your code, replacing <span>s with <i>'s! So it may make sense to get on board with what seems to be the direction of the spec, especially when it doesn't clearly conflict with the current spec. Common usage tends to dictate language rules more than the other way around. If you're old enough, do you remember that "Web site" was the official spelling when the word was new? Dictionaries insisted there must be a space and Web must be capitalized. There were semantic reasons for that. But common usage said, "Whatever, that's stupid. I'm using 'website' because it's more concise and looks better." And before long, dictionaries officially acknowledged that spelling as correct.

4. So I'm going ahead and using it.

So, <i> provides more meaning to machines because of the spec, it provides more meaning to humans because we easily associate "i" with "icon", and it's only one letter long. Win! And if you make sure to include equivalent text either inside the <i> tag or right next to it (as Twitter does), then screen readers understand where to click to reply, the link is usable if CSS doesn't load, and human readers with good eyesight and a decent browser see a pretty icon. With all this in mind, I don't see the downside.

How do I use Ruby for shell scripting?

The answer by webmat is perfect. I just want to point you to a addition. If you have to deal a lot with command line parameters for your scripts, you should use optparse. It is simple and helps you tremendously.

What is the effect of extern "C" in C++?

Decompile a g++ generated binary to see what is going on

main.cpp

void f() {}
void g();

extern "C" {
    void ef() {}
    void eg();
}

/* Prevent g and eg from being optimized away. */
void h() { g(); eg(); }

Compile and disassemble the generated ELF output:

g++ -c -std=c++11 -Wall -Wextra -pedantic -o main.o main.cpp
readelf -s main.o

The output contains:

     8: 0000000000000000     7 FUNC    GLOBAL DEFAULT    1 _Z1fv
     9: 0000000000000007     7 FUNC    GLOBAL DEFAULT    1 ef
    10: 000000000000000e    17 FUNC    GLOBAL DEFAULT    1 _Z1hv
    11: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND _GLOBAL_OFFSET_TABLE_
    12: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND _Z1gv
    13: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND eg

Interpretation

We see that:

  • ef and eg were stored in symbols with the same name as in the code

  • the other symbols were mangled. Let's unmangle them:

    $ c++filt _Z1fv
    f()
    $ c++filt _Z1hv
    h()
    $ c++filt _Z1gv
    g()
    

Conclusion: both of the following symbol types were not mangled:

  • defined
  • declared but undefined (Ndx = UND), to be provided at link or run time from another object file

So you will need extern "C" both when calling:

  • C from C++: tell g++ to expect unmangled symbols produced by gcc
  • C++ from C: tell g++ to generate unmangled symbols for gcc to use

Things that do not work in extern C

It becomes obvious that any C++ feature that requires name mangling will not work inside extern C:

extern "C" {
    // Overloading.
    // error: declaration of C function ‘void f(int)’ conflicts with
    void f();
    void f(int i);

    // Templates.
    // error: template with C linkage
    template <class C> void f(C i) { }
}

Minimal runnable C from C++ example

For the sake of completeness and for the newbs out there, see also: How to use C source files in a C++ project?

Calling C from C++ is pretty easy: each C function only has one possible non-mangled symbol, so no extra work is required.

main.cpp

#include <cassert>

#include "c.h"

int main() {
    assert(f() == 1);
}

c.h

#ifndef C_H
#define C_H

/* This ifdef allows the header to be used from both C and C++ 
 * because C does not know what this extern "C" thing is. */
#ifdef __cplusplus
extern "C" {
#endif
int f();
#ifdef __cplusplus
}
#endif

#endif

c.c

#include "c.h"

int f(void) { return 1; }

Run:

g++ -c -o main.o -std=c++98 main.cpp
gcc -c -o c.o -std=c89 c.c
g++ -o main.out main.o c.o
./main.out

Without extern "C" the link fails with:

main.cpp:6: undefined reference to `f()'

because g++ expects to find a mangled f, which gcc did not produce.

Example on GitHub.

Minimal runnable C++ from C example

Calling C++ from C is a bit harder: we have to manually create non-mangled versions of each function we want to expose.

Here we illustrate how to expose C++ function overloads to C.

main.c

#include <assert.h>

#include "cpp.h"

int main(void) {
    assert(f_int(1) == 2);
    assert(f_float(1.0) == 3);
    return 0;
}

cpp.h

#ifndef CPP_H
#define CPP_H

#ifdef __cplusplus
// C cannot see these overloaded prototypes, or else it would get confused.
int f(int i);
int f(float i);
extern "C" {
#endif
int f_int(int i);
int f_float(float i);
#ifdef __cplusplus
}
#endif

#endif

cpp.cpp

#include "cpp.h"

int f(int i) {
    return i + 1;
}

int f(float i) {
    return i + 2;
}

int f_int(int i) {
    return f(i);
}

int f_float(float i) {
    return f(i);
}

Run:

gcc -c -o main.o -std=c89 -Wextra main.c
g++ -c -o cpp.o -std=c++98 cpp.cpp
g++ -o main.out main.o cpp.o
./main.out

Without extern "C" it fails with:

main.c:6: undefined reference to `f_int'
main.c:7: undefined reference to `f_float'

because g++ generated mangled symbols which gcc cannot find.

Example on GitHub.

Where is the extern "c" when I include C headers from C++?

Tested in Ubuntu 18.04.

Finding whether a point lies inside a rectangle or not

If you can't solve the problem for the rectangle try dividing the problem in to easier problems. Divide the rectangle into 2 triangles an check if the point is inside any of them like they explain in here

Essentially, you cycle through the edges on every two pairs of lines from a point. Then using cross product to check if the point is between the two lines using the cross product. If it's verified for all 3 points, then the point is inside the triangle. The good thing about this method is that it does not create any float-point errors which happens if you check for angles.

Adding Counter in shell script

Try this:

counter=0
while true; do
  if /home/hadoop/latest/bin/hadoop fs -ls /apps/hdtech/bds/quality-rt/dt=$DATE_YEST_FORMAT2 then
       echo "Files Present" | mailx -s "File Present"  -r [email protected] [email protected]
       break
  elif [[ "$counter" -gt 20 ]]; then
       echo "Counter limit reached, exit script."
       exit 1
  else
       let counter++
       echo "Sleeping for another half an hour" | mailx -s "Time to Sleep Now"  -r [email protected] [email protected]
       sleep 1800
  fi
done

Explanation

  • break - if files are present, it will break and allow the script to process the files.
  • [[ "$counter" -gt 20 ]] - if the counter variable is greater than 20, the script will exit.
  • let counter++ - increments the counter by 1 at each pass.

Getting reference to child component in parent component

You may actually go with ViewChild API...

parent.ts

<button (click)="clicked()">click</button>

export class App {
  @ViewChild(Child) vc:Child;
  constructor() {
    this.name = 'Angular2'
  }

  func(e) {
    console.log(e)

  }
  clicked(){
   this.vc.getName();
  }
}

child.ts

export class Child implements OnInit{

  onInitialized = new EventEmitter<Child>();
  ...  
  ...
  getName()
  {
     console.log('called by vc')
     console.log(this.name);
  }
}

How to convert an image to base64 encoding?

I think that it should be:

$path = 'myfolder/myimage.png';
$type = pathinfo($path, PATHINFO_EXTENSION);
$data = file_get_contents($path);
$base64 = 'data:image/' . $type . ';base64,' . base64_encode($data);

How to parse string into date?

You can use:

SELECT CONVERT(datetime, '24.04.2012', 103) AS Date

Reference: CAST and CONVERT (Transact-SQL)

What version of Java is running in Eclipse?

String runtimeVersion = System.getProperty("java.runtime.version");

should return you a string along the lines of:

1.5.0_01-b08

That's the version of Java that Eclipse is using to run your code which is not necessarily the same version that's being used to run Eclipse itself.

sweet-alert display HTML code in text

I just struggled with this. I upgraded from sweetalert 1 -> 2. This library: https://sweetalert.js.org/guides/

The example from documentation "string" doesn't work as I expected. You just can't put it like this.

content: `my es6 string <strong>template</strong>` 

How I solved it:

const template = (`my es6 string <strong'>${variable}</strong>`);
content: {
      element: 'p',
      attributes: {
        innerHTML: `${template}`,
      },
    }

There is no documentation how to do this, it was pure trial and error, but at least seems to work.

Visual Studio 2017 errors on standard headers

I upgraded VS2017 from version 15.2 to 15.8. With version 15.8 here's what happened:

Project -> Properties -> General -> Windows SDK Version -> select 10.0.15063.0 no longer worked for me! I had to change it to 10.0.17134.0 and then everything built again. After the upgrade and without making this change, I was getting the same header file errors.

I would have submitted this as a comment on one of the other answers but I don't have enough reputation yet.

How to return a complex JSON response with Node.js?

I don't know if this is really any different, but rather than iterate over the query cursor, you could do something like this:

query.exec(function (err, results){
  if (err) res.writeHead(500, err.message)
  else if (!results.length) res.writeHead(404);
  else {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.write(JSON.stringify(results.map(function (msg){ return {msgId: msg.fileName}; })));
  }
  res.end();
});

How to find the day, month and year with moment.js

Here's an example that you could use :

 var myDateVariable= moment("01/01/2019").format("dddd Do MMMM YYYY")
  • dddd : Full day Name

  • Do : day of the Month

  • MMMM : Full Month name

  • YYYY : 4 digits Year

For more informations :

https://flaviocopes.com/momentjs/

How to use a table type in a SELECT FROM statement?

Prior to Oracle 12C you cannot select from PL/SQL-defined tables, only from tables based on SQL types like this:

CREATE OR REPLACE TYPE exch_row AS OBJECT(
currency_cd VARCHAR2(9),
exch_rt_eur NUMBER,
exch_rt_usd NUMBER);


CREATE OR REPLACE TYPE exch_tbl AS TABLE OF exch_row;

In Oracle 12C it is now possible to select from PL/SQL tables that are defined in a package spec.

Instantiating a generic class in Java

Use The Constructor.newInstance method. The Class.newInstance method has been deprecated since Java 9 to enhance compiler recognition of instantiation exceptions.

public class Foo<T> {   
    public Foo()
    {
        Class<T> newT = null; 
        instantiateNew(newT);
    }

    T instantiateNew(Class<?> clsT)
    {
        T newT;
        try {
            newT = (T) clsT.getDeclaredConstructor().newInstance();
        } catch (InstantiationException | IllegalAccessException | IllegalArgumentException
            | InvocationTargetException | NoSuchMethodException | SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
        return newT;
    }
}

How to remove all options from a dropdown using jQuery / JavaScript

You didn't say on which event.Just use below on your event listener.Or in your page load

$('#models').empty()

Then to repopulate

$.getJSON('@Url.Action("YourAction","YourController")',function(data){
 var dropdown=$('#models');
dropdown.empty();  
$.each(data, function (index, item) {
    dropdown.append(
        $('<option>', {
            value: item.valueField,
            text: item.DisplayField
        }, '</option>'))
      }
     )});

Wait on the Database Engine recovery handle failed. Check the SQL server error log for potential causes

This post is high up when you google that error message, which I got when installing security patch KB4505224 on SQL Server 2017 Express i.e. None of the above worked for me, but did consume several hours trying.

The solution for me, partly from here was:

  1. uninstall SQL Server
  2. in Regional Settings / Management / System Locale, "Beta: UTF-8 support" should be OFF
  3. re-install SQL Server
  4. Let Windows install the patch.

And all was well.

More on this here.

Summarizing count and conditional aggregate functions on the same factor

Assuming that your original dataset is similar to the one you created (i.e. with NA as character. You could specify na.strings while reading the data using read.table. But, I guess NAs would be detected automatically.

The price column is factor which needs to be converted to numeric class. When you use as.numeric, all the non-numeric elements (i.e. "NA", FALSE) gets coerced to NA) with a warning.

library(dplyr)
df %>%
     mutate(price=as.numeric(as.character(price))) %>%  
     group_by(company, year, product) %>%
     summarise(total.count=n(), 
               count=sum(is.na(price)), 
               avg.price=mean(price,na.rm=TRUE),
               max.price=max(price, na.rm=TRUE))

data

I am using the same dataset (except the ... row) that was showed.

df = tbl_df(data.frame(company=c("Acme", "Meca", "Emca", "Acme", "Meca","Emca"),
 year=c("2011", "2010", "2009", "2011", "2010", "2013"), product=c("Wrench", "Hammer",
 "Sonic Screwdriver", "Fairy Dust", "Kindness", "Helping Hand"), price=c("5.67",
 "7.12", "12.99", "10.99", "NA",FALSE)))

need to test if sql query was successful

This has proven the safest mechanism for me to test for failure on insert or update:

$result = $db->query(' ... ');
if ((gettype($result) == "object" && $result->num_rows == 0) || !$result) {
   failure 
}

SQL Server 2008 - Login failed. The login is from an untrusted domain and cannot be used with Windows authentication

I was getting this error too, although my issue was that I kept switching between two corporate networks via my Virtual Machine, with different access credentials. I had to run the command prompt:

ipconfig /renew

After this my network issues were resolved and I could connect once again to SQL.

Prevent Sequelize from outputting SQL to the console on execution of query?

I am using Sequelize ORM 6.0.0 and am using "logging": false as the rest but posted my answer for latest version of the ORM.

const sequelize = new Sequelize(
        process.env.databaseName,
        process.env.databaseUser,
        process.env.password,
        {
            host: process.env.databaseHost,
            dialect: process.env.dialect,
            "logging": false,
            define: {
                // Table names won't be pluralized.
                freezeTableName: true,
                // All tables won't have "createdAt" and "updatedAt" Auto fields.
                timestamps: false
            }
        }
    );

Note: I am storing my secretes in a configuration file .env observing the 12-factor methodology.

Invoke-Command error "Parameter set cannot be resolved using the specified named parameters"

The error you have is because -credential without -computername can't exist.

You can try this way:

Invoke-Command -Credential $migratorCreds  -ScriptBlock ${function:Get-LocalUsers} -ArgumentList $xmlPRE,$migratorCreds -computername YOURCOMPUTERNAME

How do I force files to open in the browser instead of downloading (PDF)?

This is for ASP.NET MVC

In your cshtml page:

<section>
    <h4><a href="@Url.Action("Download", "Document", new { id = @Model.GUID })"><i class="fa fa-download"></i> @Model.Name</a></h4>
    <object data="@Url.Action("View", "Document", new { id = @Model.GUID })" type="application/pdf" width="100%" height="800" class="col-md-12">
        <h2>Your browser does not support viewing PDFs, click on the link above to download the document.</h2>
    </object>
</section>

In your controller:

public ActionResult Download(Guid id)
    {
        if (id == Guid.Empty)
            return null;

        var model = GetModel(id);

        return File(model.FilePath, "application/pdf", model.FileName);
    }

public FileStreamResult View(Guid id)
    {
        if (id == Guid.Empty)
            return null;

        var model = GetModel(id);

        FileStream fs = new FileStream(model.FilePath, FileMode.Open, FileAccess.Read);

        return File(fs, "application/pdf");
    }

cannot load such file -- bundler/setup (LoadError)

I ran into the same issue, but I think it was due to spring caching some gems and configurations. I fixed it by running gem pristine --all.

This restores installed gems to pristine condition from files located in the gem cache.

or you can just try for your gem like

gem pristine your_gem_name

Change the current directory from a Bash script

Simply go to

yourusername/.bashrc (or yourusername/.bash_profile on MAC) by an editor

and add this code next to the last line:

alias yourcommand="cd /the_path_you_wish"

Then quit editor.

Then type:

source ~/.bashrc or source ~/.bash_profile on MAC.

now you can use: yourcommand in terminal

How to avoid reverse engineering of an APK file?

As someone who worked extensively on payment platforms, including one mobile payments application (MyCheck), I would say that you need to delegate this behaviour to the server, no user name or password for the payment processor (whichever it is) should be stored or hardcoded in the mobile application, that's the last thing you want, because the source can be understood even when if you obfuscate the code.

Also, you shouldn't store credit cards or payment tokens on the application, everything should be, again, delegated to a service you built, it will also allow you later on, be PCI-compliant more easily, and the Credit Card companies won't breath down your neck (like they did for us).

How can I select an element by name with jQuery?

You can use any attribute as selector with [attribute_name=value].

$('td[name=tcol1]').hide();

Change Title of Javascript Alert

You can't, this is determined by the browser, for the user's safety and security. For example you can't make it say "Virus detected" with a message of "Would you like to quarantine it now?"...at least not as an alert().

There are plenty of JavaScript Modal Dialogs out there though, that are far more customizable than alert().

Advantages of SQL Server 2008 over SQL Server 2005?

There are new features added. But, you will have to see if it is worth the upgrade. Some good improvements in Management Studio 2008 though, especially the intellisense for the Query Editor.

How to call a shell script from python code?

The subprocess module will help you out.

Blatantly trivial example:

>>> import subprocess
>>> subprocess.call(['sh', './test.sh']) # Thanks @Jim Dennis for suggesting the []
0 
>>> 

Where test.sh is a simple shell script and 0 is its return value for this run.

Codeigniter - multiple database connections

The best way is to use different database groups. If you want to keep using the master database as usual ($this->db) just turn off persistent connexion configuration option to your secondary database(s). Only master database should work with persistent connexion :

Master database

$db['default']['hostname'] = "localhost";
$db['default']['username'] = "root";
$db['default']['password'] = "";
$db['default']['database'] = "database_name";
$db['default']['dbdriver'] = "mysql";
$db['default']['dbprefix'] = "";
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = FALSE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci";
$db['default']['swap_pre'] = "";
$db['default']['autoinit'] = TRUE;
$db['default']['stricton'] = FALSE;

Secondary database (notice pconnect is set to false)

$db['otherdb']['hostname'] = "localhost";
$db['otherdb']['username'] = "root";
$db['otherdb']['password'] = "";
$db['otherdb']['database'] = "other_database_name";
$db['otherdb']['dbdriver'] = "mysql";
$db['otherdb']['dbprefix'] = "";
$db['otherdb']['pconnect'] = FALSE;
$db['otherdb']['db_debug'] = FALSE;
$db['otherdb']['cache_on'] = FALSE;
$db['otherdb']['cachedir'] = "";
$db['otherdb']['char_set'] = "utf8";
$db['otherdb']['dbcollat'] = "utf8_general_ci";
$db['otherdb']['swap_pre'] = "";
$db['otherdb']['autoinit'] = TRUE;
$db['otherdb']['stricton'] = FALSE;

Then you can use secondary databases as database objects while using master database as usual :

// use master dataabse
$users = $this->db->get('users');

// connect to secondary database
$otherdb = $this->load->database('otherdb', TRUE);
$stuff = $otherdb->get('struff');
$otherdb->insert_batch('users', $users->result_array());

// keep using master database as usual, for example insert stuff from other database
$this->db->insert_batch('stuff', $stuff->result_array());

How do I check that multiple keys are in a dict in a single pass?

>>> if 'foo' in foo and 'bar' in foo:
...     print 'yes'
... 
yes

Jason, () aren't necessary in Python.

Check if XML Element exists

Following is a simple function to check if a particular node is present or not in the xml file.

public boolean envParamExists(String xmlFilePath, String paramName){
    try{
        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File(xmlFilePath));
        doc.getDocumentElement().normalize();
        if(doc.getElementsByTagName(paramName).getLength()>0)
            return true;
        else
            return false;
    }catch (Exception e) {
        //error handling
    }
    return false;
}

How to get the difference between two arrays in JavaScript?

This question is old but is still the top hit for javascript array subtraction so I wanted to add the solution I am using. This fits for the following case:

var a1 = [1,2,2,3]
var a2 = [1,2]
//result = [2,3]

The following method will produced the desired result:

function arrayDifference(minuend, subtrahend) {
  for (var i = 0; i < minuend.length; i++) {
    var j = subtrahend.indexOf(minuend[i])
    if (j != -1) {
      minuend.splice(i, 1);
      subtrahend.splice(j, 1);
    }
  }
  return minuend;
}

It should be noted that the function does not include values from the subtrahend that are not present in the minuend:

var a1 = [1,2,3]
var a2 = [2,3,4]
//result = [1]

How should I pass multiple parameters to an ASP.Net Web API GET?

    public HttpResponseMessage Get(int id,string numb)
    {
        //this will differ according to your entity name
        using (MarketEntities entities = new MarketEntities())
        {
          var ent=  entities.Api_For_Test.FirstOrDefault(e => e.ID == id && e.IDNO.ToString()== numb);
            if (ent != null)
            {
                return Request.CreateResponse(HttpStatusCode.OK, ent);
            }
            else
            {
                return Request.CreateErrorResponse(HttpStatusCode.NotFound, "Applicant with ID " + id.ToString() + " not found in the system");
            }
        }
    }

Using C++ base class constructors?

Here is a good discussion about superclass constructor calling rules. You always want the base class constructor to be called before the derived class constructor in order to form an object properly. Which is why this form is used

  B( int v) : A( v )
  {
  }

Apache Prefork vs Worker MPM

Apache's Multi-Processing Modules (MPMs) are responsible for binding to network ports on the machine, accepting requests, and dispatching children to handle the requests (http://httpd.apache.org/docs/2.2/mpm.html).

They're like any other Apache module, except that just one and only one MPM must be loaded into the server at any time. MPMs are chosen during configuration and compiled into the server by using the argument --with-mpm=NAME with the configure script where NAME is the name of the desired MPM.

Apache will use a default MPM for each operating system unless a different one is choosen at compile-time (for instance on Windows mpm_winnt is used by default). Here's the list of operating systems and their default MPMs:

  • BeOS beos
  • Netware mpm_netware
  • OS/2 mpmt_os2
  • Unix/Linux prefork (update for Apache version = 2.4: prefork, worker, or event, depending on platform capabilities)
  • Windows mpm_winnt

To check what modules are compiled into the server use the command-line option -l (here is the documentation). For instance on a Windows installation you might get something like:

> httpd -l
Compiled in modules:
  core.c
  mod_win32.c
  mpm_winnt.c
  http_core.c
  mod_so.c

As of version 2.2 this is the list of available core features and MPM modules:

  • core - Core Apache HTTP Server features that are always available
  • mpm_common - A collection of directives that are implemented by more than one multi-processing module (MPM)
  • beos - This Multi-Processing Module is optimized for BeOS.
  • event - An experimental variant of the standard worker MPM
  • mpm_netware Multi-Processing Module implementing an exclusively threaded web server optimized for Novell NetWare
  • mpmt_os2 Hybrid multi-process, multi-threaded MPM for OS/2
  • prefork Implements a non-threaded, pre-forking web server
  • mpm_winnt - This Multi-Processing Module is optimized for Windows NT.
  • worker - Multi-Processing Module implementing a hybrid multi-threaded multi-process web server

Now, to the difference between prefork and worker.

The prefork MPM

implements a non-threaded, pre-forking web server that handles requests in a manner similar to Apache 1.3. It is appropriate for sites that need to avoid threading for compatibility with non-thread-safe libraries. It is also the best MPM for isolating each request, so that a problem with a single request will not affect any other.

The worker MPM implements a hybrid multi-process multi-threaded server and gives better performance, hence it should be preferred unless one is using other modules that contain non-thread-safe libraries (see also this discussion or this on Serverfault).

Select subset of columns in data.table R

Option using dplyr

require(dplyr)
dt<-as.data.frame(matrix(runif(10*10),10,10))
dt <- select(dt, -V1, -V2, -V3, -V4)
cor(dt)

Check for null variable in Windows batch

rem set defaults:
set filename1="c:\file1.txt"
set filename2="c:\file2.txt"
set filename3="c:\file3.txt"
rem set parameters:
IF NOT "a%1"=="a" (set filename1="%1")
IF NOT "a%2"=="a" (set filename2="%2")
IF NOT "a%3"=="a" (set filename1="%3")
echo %filename1%, %filename2%, %filename3%

Be careful with quotation characters though, you may or may not need them in your variables.

Maximum value for long integer

Long integers:

There is no explicitly defined limit. The amount of available address space forms a practical limit.
(Taken from this site). See the docs on Numeric Types where you'll see that Long integers have unlimited precision. In Python 2, Integers will automatically switch to longs when they grow beyond their limit:

>>> import sys
>>> type(sys.maxsize)
<type 'int'>
>>> type(sys.maxsize+1)
<type 'long'>


for integers we have

maxint and maxsize:

The maximum value of an int can be found in Python 2.x with sys.maxint. It was removed in Python 3, but sys.maxsize can often be used instead. From the changelog:

The sys.maxint constant was removed, since there is no longer a limit to the value of integers. However, sys.maxsize can be used as an integer larger than any practical list or string index. It conforms to the implementation’s “natural” integer size and is typically the same as sys.maxint in previous releases on the same platform (assuming the same build options).

and, for anyone interested in the difference (Python 2.x):

sys.maxint The largest positive integer supported by Python’s regular integer type. This is at least 2**31-1. The largest negative integer is -maxint-1 — the asymmetry results from the use of 2’s complement binary arithmetic.

sys.maxsize The largest positive integer supported by the platform’s Py_ssize_t type, and thus the maximum size lists, strings, dicts, and many other containers can have.

and for completeness, here's the Python 3 version:

sys.maxsize An integer giving the maximum value a variable of type Py_ssize_t can take. It’s usually 2^31 - 1 on a 32-bit platform and 2^63 - 1 on a 64-bit platform.

floats:

There's float("inf") and float("-inf"). These can be compared to other numeric types:

>>> import sys
>>> float("inf") > sys.maxsize
True

Recommended add-ons/plugins for Microsoft Visual Studio

It's not a Visual Studio add in, but it is a tool that I couldn't use Visual Studio without it...

ClipX - it's works with the normal clipboard, but saves the entries to a searchable list, you can use copy and paste as ususal, but you can hit CTRL+SHIFT+V and the list pops up. It works with images, text, etc. It even persists after you reboot your computer.

How do I write a Python dictionary to a csv file?

Your code was very close to working.

Try using a regular csv.writer rather than a DictWriter. The latter is mainly used for writing a list of dictionaries.

Here's some code that writes each key/value pair on a separate row:

import csv

somedict = dict(raymond='red', rachel='blue', matthew='green')
with open('mycsvfile.csv','wb') as f:
    w = csv.writer(f)
    w.writerows(somedict.items())

If instead you want all the keys on one row and all the values on the next, that is also easy:

with open('mycsvfile.csv','wb') as f:
    w = csv.writer(f)
    w.writerow(somedict.keys())
    w.writerow(somedict.values())

Pro tip: When developing code like this, set the writer to w = csv.writer(sys.stderr) so you can more easily see what is being generated. When the logic is perfected, switch back to w = csv.writer(f).

Best way to do multiple constructors in PHP

Let me add my grain of sand here

I personally like adding a constructors as static functions that return an instance of the class (the object). The following code is an example:

 class Person
 {
     private $name;
     private $email;

     public static function withName($name)
     {
         $person = new Person();
         $person->name = $name;

         return $person;
     }

     public static function withEmail($email)
     {
         $person = new Person();
         $person->email = $email;

         return $person;
     }
 }

Note that now you can create instance of the Person class like this:

$person1 = Person::withName('Example');
$person2 = Person::withEmail('yo@mi_email.com');

I took that code from:

http://alfonsojimenez.com/post/30377422731/multiple-constructors-in-php

How to delete an SVN project from SVN repository

In the case where you simply want to delete a project from the head revision, so that it no longer shows up in your repo when you run svn list file:///path/to/repo/ just run:

svn delete file:///path/to/repo/project 

However, if you need to delete all record of it in the repo, use another method.

How to fix "containing working copy admin area is missing" in SVN?

First of all checkout the project into your system in a folder. Then remove the .svn folder from conflict project and copy the .svn folder from new checkout folder and paste into your working copy folder. Then problem is solved.

Angular2: How to load data before rendering the component?

update

original

When console.log(this.ev) is executed after this.fetchEvent();, this doesn't mean the fetchEvent() call is done, this only means that it is scheduled. When console.log(this.ev) is executed, the call to the server is not even made and of course has not yet returned a value.

Change fetchEvent() to return a Promise

     fetchEvent(){
        return  this._apiService.get.event(this.eventId).then(event => {
            this.ev = event;
            console.log(event); // Has a value
            console.log(this.ev); // Has a value
        });
     }

change ngOnInit() to wait for the Promise to complete

    ngOnInit() {
        this.fetchEvent().then(() =>
        console.log(this.ev)); // Now has value;
    }

This actually won't buy you much for your use case.

My suggestion: Wrap your entire template in an <div *ngIf="isDataAvailable"> (template content) </div>

and in ngOnInit()

    isDataAvailable:boolean = false;

    ngOnInit() {
        this.fetchEvent().then(() =>
        this.isDataAvailable = true); // Now has value;
    }

Use of Finalize/Dispose method in C#

I agree with pm100 (and should have explicitly said this in my earlier post).

You should never implement IDisposable in a class unless you need it. To be very specific, there are about 5 times when you would ever need/should implement IDisposable:

  1. Your class explicitly contains (i.e. not via inheritance) any managed resources which implement IDisposable and should be cleaned up once your class is no longer used. For example, if your class contains an instance of a Stream, DbCommand, DataTable, etc.

  2. Your class explicitly contains any managed resources which implement a Close() method - e.g. IDataReader, IDbConnection, etc. Note that some of these classes do implement IDisposable by having Dispose() as well as a Close() method.

  3. Your class explicitly contains an unmanaged resource - e.g. a COM object, pointers (yes, you can use pointers in managed C# but they must be declared in 'unsafe' blocks, etc. In the case of unmanaged resources, you should also make sure to call System.Runtime.InteropServices.Marshal.ReleaseComObject() on the RCW. Even though the RCW is, in theory, a managed wrapper, there is still reference counting going on under the covers.

  4. If your class subscribes to events using strong references. You need to unregister/detach yourself from the events. Always to make sure these are not null first before trying to unregister/detach them!.

  5. Your class contains any combination of the above...

A recommended alternative to working with COM objects and having to use Marshal.ReleaseComObject() is to use the System.Runtime.InteropServices.SafeHandle class.

The BCL (Base Class Library Team) has a good blog post about it here http://blogs.msdn.com/bclteam/archive/2005/03/16/396900.aspx

One very important note to make is that if you are working with WCF and cleaning up resources, you should ALMOST ALWAYS avoid the 'using' block. There are plenty of blog posts out there and some on MSDN about why this is a bad idea. I have also posted about it here - Don't use 'using()' with a WCF proxy

jQuery - Follow the cursor with a DIV

You don't need jQuery for this. Here's a simple working example:

<!DOCTYPE html>
<html>
    <head>
        <title>box-shadow-experiment</title>
        <style type="text/css">
            #box-shadow-div{
                position: fixed;
                width: 1px;
                height: 1px;
                border-radius: 100%;
                background-color:black;
                box-shadow: 0 0 10px 10px black;
                top: 49%;
                left: 48.85%;
            }
        </style>
        <script type="text/javascript">
            window.onload = function(){
                var bsDiv = document.getElementById("box-shadow-div");
                var x, y;
    // On mousemove use event.clientX and event.clientY to set the location of the div to the location of the cursor:
                window.addEventListener('mousemove', function(event){
                    x = event.clientX;
                    y = event.clientY;                    
                    if ( typeof x !== 'undefined' ){
                        bsDiv.style.left = x + "px";
                        bsDiv.style.top = y + "px";
                    }
                }, false);
            }
        </script>
    </head>
    <body>
        <div id="box-shadow-div"></div>
    </body>
</html>

I chose position: fixed; so scrolling wouldn't be an issue.

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

I guess, a column value in a foreign key table should match with the column value of the primary key table. If we are trying to create a foreign key constraint between two tables where the value inside one column(going to be the foreign key) is different from the column value of the primary key table then it will throw the message.

So it is always recommended to insert only those values in the Foreign key column which are present in the Primary key table column.

For ex. If the Primary table column has values 1, 2, 3 and in Foreign key column the values inserted are different, then the query would not be executed as it expects the values to be between 1 & 3.

C++ sorting and keeping track of indexes

Beautiful solution by @Lukasz Wiklendt! Although in my case I needed something more generic so I modified it a bit:

template <class RAIter, class Compare>
vector<size_t> argSort(RAIter first, RAIter last, Compare comp) {

  vector<size_t> idx(last-first);
  iota(idx.begin(), idx.end(), 0);

  auto idxComp = [&first,comp](size_t i1, size_t i2) {
      return comp(first[i1], first[i2]);
  };

  sort(idx.begin(), idx.end(), idxComp);

  return idx;
}

Example: Find indices sorting a vector of strings by length, except for the first element which is a dummy.

vector<string> test = {"dummy", "a", "abc", "ab"};

auto comp = [](const string &a, const string& b) {
    return a.length() > b.length();
};

const auto& beginIt = test.begin() + 1;
vector<size_t> ind = argSort(beginIt, test.end(), comp);

for(auto i : ind)
    cout << beginIt[i] << endl;

prints:

abc
ab
a

Ternary operator in AngularJS templates

While you can use the condition && if-true-part || if-false-part-syntax in older versions of angular, the usual ternary operator condition ? true-part : false-part is available in Angular 1.1.5 and later.

Output ("echo") a variable to a text file

Note: The answer below is written from the perspective of Windows PowerShell.
However, it applies to the cross-platform PowerShell Core edition (v6+) as well, except that the latter - commendably - consistently defaults to BOM-less UTF-8 character encoding, which is the most widely compatible one across platforms and cultures.
.


To complement bigtv's helpful answer helpful answer with a more concise alternative and background information:

# > $file is effectively the same as | Out-File $file
# Objects are written the same way they display in the console.
# Default character encoding is UTF-16LE (mostly 2 bytes per char.), with BOM.
# Use Out-File -Encoding <name> to change the encoding.
$env:computername > $file

# Set-Content calls .ToString() on each object to output.
# Default character encoding is "ANSI" (culture-specific, single-byte).
# Use Set-Content -Encoding <name> to change the encoding.
# Use Set-Content rather than Add-Content; the latter is for *appending* to a file.
$env:computername | Set-Content $file 

When outputting to a text file, you have 2 fundamental choices that use different object representations and, in Windows PowerShell (as opposed to PowerShell Core), also employ different default character encodings:

  • Out-File (or >) / Out-File -Append (or >>):

    • Suitable for output objects of any type, because PowerShell's default output formatting is applied to the output objects.

      • In other words: you get the same output as when printing to the console.
    • The default encoding, which can be changed with the -Encoding parameter, is Unicode, which is UTF-16LE in which most characters are encoded as 2 bytes. The advantage of a Unicode encoding such as UTF-16LE is that it is a global alphabet, capable of encoding all characters from all human languages.

      • In PSv5.1+, you can change the encoding used by > and >>, via the $PSDefaultParameterValues preference variable, taking advantage of the fact that > and >> are now effectively aliases of Out-File and Out-File -Append. To change to UTF-8, for instance, use:
        $PSDefaultParameterValues['Out-File:Encoding']='UTF8'
  • Set-Content / Add-Content:

    • For writing strings and instances of types known to have meaningful string representations, such as the .NET primitive data types (Booleans, integers, ...).

      • .psobject.ToString() method is called on each output object, which results in meaningless representations for types that don't explicitly implement a meaningful representation; [hashtable] instances are an example:
        @{ one = 1 } | Set-Content t.txt writes literal System.Collections.Hashtable to t.txt, which is the result of @{ one = 1 }.ToString().
    • The default encoding, which can be changed with the -Encoding parameter, is Default, which is the system's "ANSI" code page, a the single-byte culture-specific legacy encoding for non-Unicode applications, most commonly Windows-1252.
      Note that the documentation currently incorrectly claims that ASCII is the default encoding.

    • Note that Add-Content's purpose is to append content to an existing file, and it is only equivalent to Set-Content if the target file doesn't exist yet.
      Furthermore, the default or specified encoding is blindly applied, irrespective of the file's existing contents' encoding.

Out-File / > / Set-Content / Add-Content all act culture-sensitively, i.e., they produce representations suitable for the current culture (locale), if available (though custom formatting data is free to define its own, culture-invariant representation - see Get-Help about_format.ps1xml). This contrasts with PowerShell's string expansion (string interpolation in double-quoted strings), which is culture-invariant - see this answer of mine.

As for performance: Since Set-Content doesn't have to apply default formatting to its input, it performs better.


As for the OP's symptom with Add-Content:

Since $env:COMPUTERNAME cannot contain non-ASCII characters, Add-Content's output, using "ANSI" encoding, should not result in ? characters in the output, and the likeliest explanation is that the ? were part of the preexisting content in output file $file, which Add-Content appended to.

Most efficient conversion of ResultSet to JSON?

I think there's a way to use less memory (a fixed and not linear amount depending on data cardinality) but this imply to change the method signature. In fact we may print the Json data directly on an output stream as soon as we fetch them from the ResultSet: the already written data will be garbage collected since we don't need an array that keeps them in memory.

I use GSON that accepts type adapters. I wrote a type adapter to convert ResultSet to JsonArray and it looks very like to your code. I'm waiting the "Gson 2.1: Targeted Dec 31, 2011" release which will have the "Support for user-defined streaming type adapters". Then I'll modify my adapter to be a streaming adapter.


Update

As promised I'm back but not with Gson, instead with Jackson 2. Sorry to be late (of 2 years).

Preface: The key to use less memory of the result itsef is in the "server side" cursor. With this kind of cursors (a.k.a. resultset to Java devs) the DBMS sends data incrementally to client (a.k.a. driver) as the client goes forward with the reading. I think Oracle cursor are server side by default. For MySQL > 5.0.2 look for useCursorFetch at connection url paramenter. Check about your favourite DBMS.

1: So to use less memory we must:

  • use server side cursor behind the scene
  • use resultset open as read only and, of course, forward only;
  • avoid to load all the cursor in a list (or a JSONArray) but write each row directly on an output line, where for output line I mean an output stream or a writer or also a json generator that wraps an output stream or a writer.

2: As Jackson Documentation says:

Streaming API is best performing (lowest overhead, fastest read/write; other 2 methods build on it)

3: I see you in your code use getInt, getBoolean. getFloat... of ResultSet without wasNull. I expect this can yield problems.

4: I used arrays to cache thinks and to avoid to call getters each iteration. Although not a fan of the switch/case construct, I used it for that int SQL Types.

The answer: Not yet fully tested, it's based on Jackson 2.2:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.2.2</version>
</dependency>

The ResultSetSerializer object instructs Jackson on how to serialize (tranform the object to JSON) a ResultSet. It uses the Jackson Streaming API inside. Here the code of a test:

SimpleModule module = new SimpleModule();
module.addSerializer(new ResultSetSerializer());

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(module);

[ . . . do the query . . . ]
ResultSet resultset = statement.executeQuery(query);

// Use the DataBind Api here
ObjectNode objectNode = objectMapper.createObjectNode();

// put the resultset in a containing structure
objectNode.putPOJO("results", resultset);

// generate all
objectMapper.writeValue(stringWriter, objectNode);

And, of course, the code of the ResultSetSerializer class:

public class ResultSetSerializer extends JsonSerializer<ResultSet> {

    public static class ResultSetSerializerException extends JsonProcessingException{
        private static final long serialVersionUID = -914957626413580734L;

        public ResultSetSerializerException(Throwable cause){
            super(cause);
        }
    }

    @Override
    public Class<ResultSet> handledType() {
        return ResultSet.class;
    }

    @Override
    public void serialize(ResultSet rs, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {

        try {
            ResultSetMetaData rsmd = rs.getMetaData();
            int numColumns = rsmd.getColumnCount();
            String[] columnNames = new String[numColumns];
            int[] columnTypes = new int[numColumns];

            for (int i = 0; i < columnNames.length; i++) {
                columnNames[i] = rsmd.getColumnLabel(i + 1);
                columnTypes[i] = rsmd.getColumnType(i + 1);
            }

            jgen.writeStartArray();

            while (rs.next()) {

                boolean b;
                long l;
                double d;

                jgen.writeStartObject();

                for (int i = 0; i < columnNames.length; i++) {

                    jgen.writeFieldName(columnNames[i]);
                    switch (columnTypes[i]) {

                    case Types.INTEGER:
                        l = rs.getInt(i + 1);
                        if (rs.wasNull()) {
                            jgen.writeNull();
                        } else {
                            jgen.writeNumber(l);
                        }
                        break;

                    case Types.BIGINT:
                        l = rs.getLong(i + 1);
                        if (rs.wasNull()) {
                            jgen.writeNull();
                        } else {
                            jgen.writeNumber(l);
                        }
                        break;

                    case Types.DECIMAL:
                    case Types.NUMERIC:
                        jgen.writeNumber(rs.getBigDecimal(i + 1));
                        break;

                    case Types.FLOAT:
                    case Types.REAL:
                    case Types.DOUBLE:
                        d = rs.getDouble(i + 1);
                        if (rs.wasNull()) {
                            jgen.writeNull();
                        } else {
                            jgen.writeNumber(d);
                        }
                        break;

                    case Types.NVARCHAR:
                    case Types.VARCHAR:
                    case Types.LONGNVARCHAR:
                    case Types.LONGVARCHAR:
                        jgen.writeString(rs.getString(i + 1));
                        break;

                    case Types.BOOLEAN:
                    case Types.BIT:
                        b = rs.getBoolean(i + 1);
                        if (rs.wasNull()) {
                            jgen.writeNull();
                        } else {
                            jgen.writeBoolean(b);
                        }
                        break;

                    case Types.BINARY:
                    case Types.VARBINARY:
                    case Types.LONGVARBINARY:
                        jgen.writeBinary(rs.getBytes(i + 1));
                        break;

                    case Types.TINYINT:
                    case Types.SMALLINT:
                        l = rs.getShort(i + 1);
                        if (rs.wasNull()) {
                            jgen.writeNull();
                        } else {
                            jgen.writeNumber(l);
                        }
                        break;

                    case Types.DATE:
                        provider.defaultSerializeDateValue(rs.getDate(i + 1), jgen);
                        break;

                    case Types.TIMESTAMP:
                        provider.defaultSerializeDateValue(rs.getTime(i + 1), jgen);
                        break;

                    case Types.BLOB:
                        Blob blob = rs.getBlob(i);
                        provider.defaultSerializeValue(blob.getBinaryStream(), jgen);
                        blob.free();
                        break;

                    case Types.CLOB:
                        Clob clob = rs.getClob(i);
                        provider.defaultSerializeValue(clob.getCharacterStream(), jgen);
                        clob.free();
                        break;

                    case Types.ARRAY:
                        throw new RuntimeException("ResultSetSerializer not yet implemented for SQL type ARRAY");

                    case Types.STRUCT:
                        throw new RuntimeException("ResultSetSerializer not yet implemented for SQL type STRUCT");

                    case Types.DISTINCT:
                        throw new RuntimeException("ResultSetSerializer not yet implemented for SQL type DISTINCT");

                    case Types.REF:
                        throw new RuntimeException("ResultSetSerializer not yet implemented for SQL type REF");

                    case Types.JAVA_OBJECT:
                    default:
                        provider.defaultSerializeValue(rs.getObject(i + 1), jgen);
                        break;
                    }
                }

                jgen.writeEndObject();
            }

            jgen.writeEndArray();

        } catch (SQLException e) {
            throw new ResultSetSerializerException(e);
        }
    }
}

Call to a member function fetch_assoc() on boolean in <path>

You have to update the php.ini config file with in your host provider's server, trust me on this, more than likely there is nothing wrong with your code. It took me almost a month and a half to realize that most hosting servers are not up to date on php.ini files, eg. php 5.5 or later, I believe.

How to resolve ORA 00936 Missing Expression Error?

update INC.PROV_CSP_DEMO_ADDR_TEMP pd 
set pd.practice_name = (
    select PRSQ_COMMENT FROM INC.CMC_PRSQ_SITE_QA PRSQ
    WHERE PRSQ.PRSQ_MCTR_ITEM = 'PRNM' 
    AND PRSQ.PRAD_ID = pd.provider_id
    AND PRSQ.PRAD_TYPE = pd.prov_addr_type
    AND ROWNUM = 1
)

How to import other Python files?

In case the module you want to import is not in a sub-directory, then try the following and run app.py from the deepest common parent directory:

Directory Structure:

/path/to/common_dir/module/file.py
/path/to/common_dir/application/app.py
/path/to/common_dir/application/subpath/config.json

In app.py, append path of client to sys.path:

import os, sys, inspect

sys.path.append(os.getcwd())
from module.file import MyClass
instance = MyClass()

Optional (If you load e.g. configs) (Inspect seems to be the most robust one for my use cases)

# Get dirname from inspect module
filename = inspect.getframeinfo(inspect.currentframe()).filename
dirname = os.path.dirname(os.path.abspath(filename))
MY_CONFIG = os.path.join(dirname, "subpath/config.json")

Run

user@host:/path/to/common_dir$ python3 application/app.py

This solution works for me in cli, as well as PyCharm.

Custom seekbar (thumb size, color and background)

  • First at all, use android:splitTrack="false" for the transparency problem of your thumb.

  • For the seekbar.png, you have to use a 9 patch. It would be good for the rounded border and the shadow of your image.

How to throw a C++ exception

You could define a message to throw when a certain error occurs:

throw std::invalid_argument( "received negative value" );

or you could define it like this:

std::runtime_error greatScott("Great Scott!");          
double getEnergySync(int year) {                        
    if (year == 1955 || year == 1885) throw greatScott; 
    return 1.21e9;                                      
}                                                       

Typically, you would have a try ... catch block like this:

try {
// do something that causes an exception
}catch (std::exception& e){ std::cerr << "exception: " << e.what() << std::endl; }

What is the default Jenkins password?

If you don't create a new user when you installed jenkins, then:

user: admin pass: go to C:\Program Files (x86)\Jenkins\secrets and open the file initialAdminPassword

How to get Latitude and Longitude of the mobile device in android?

You can use FusedLocationProvider

For using Fused Location Provider in your project you will have to add the google play services location dependency in our app level build.gradle file

dependencies {
   implementation fileTree(dir: 'libs', include: ['*.jar'])
   ...
   ...
   ...
   implementation 'com.google.android.gms:play-services-location:17.0.0'
}

Permissions in Manifest

Apps that use location services must request location permissions. Android offers two location permissions: ACCESS_COARSE_LOCATION and ACCESS_FINE_LOCATION.

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

As you may know that from Android 6.0 (Marshmallow) you must request permissions for important access in the runtime. Cause it’s a security issue where while installing an application, user may not clearly understand about an important permission of their device.

ActivityCompat.requestPermissions(
    this,
    arrayOf(Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION),
    PERMISSION_ID
)

Then you can use the FusedLocationProvider Client to get the updated location in your desired place.

    mFusedLocationClient.lastLocation.addOnCompleteListener(this) { task ->
        var location: Location? = task.result
        if (location == null) {
            requestNewLocationData()
        } else {
            findViewById<TextView>(R.id.latTextView).text = location.latitude.toString()
            findViewById<TextView>(R.id.lonTextView).text = location.longitude.toString()
        }
    }

You can also check certain configuration like if the device has location settings on or not. You can also check the article on Detect Current Latitude & Longitude using Kotlin in Android for more functionality. If there is no cache location then it will catch the current location using:

private fun requestNewLocationData() {
    var mLocationRequest = LocationRequest()
    mLocationRequest.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
    mLocationRequest.interval = 0
    mLocationRequest.fastestInterval = 0
    mLocationRequest.numUpdates = 1

    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
    mFusedLocationClient!!.requestLocationUpdates(
            mLocationRequest, mLocationCallback,
            Looper.myLooper()
    )
}

Determine the data types of a data frame's columns

Here is a function that is part of the helpRFunctions package that will return a list of all of the various data types in your data frame, as well as the specific variable names associated with that type.

install.package('devtools') # Only needed if you dont have this installed.
library(devtools)
install_github('adam-m-mcelhinney/helpRFunctions')
library(helpRFunctions)
my.data <- data.frame(y=rnorm(5), 
                  x1=c(1:5), 
                  x2=c(TRUE, TRUE, FALSE, FALSE, FALSE),
                  X3=letters[1:5])
t <- list.df.var.types(my.data)
t$factor
t$integer
t$logical
t$numeric

You could then do something like var(my.data[t$numeric]).

Hope this is helpful!

Node.js: get path from the request

simply call req.url. that should do the work. you'll get something like /something?bla=foo

Add spaces between the characters of a string in Java?

This would work for inserting any character any particular position in your String.

public static String insertCharacterForEveryNDistance(int distance, String original, char c){
    StringBuilder sb = new StringBuilder();
    char[] charArrayOfOriginal = original.toCharArray();
    for(int ch = 0 ; ch < charArrayOfOriginal.length ; ch++){
        if(ch % distance == 0)
            sb.append(c).append(charArrayOfOriginal[ch]);
        else
            sb.append(charArrayOfOriginal[ch]);
    }
    return sb.toString();
}

Then call it like this

String result = InsertSpaces.insertCharacterForEveryNDistance(1, "5434567845678965", ' ');
        System.out.println(result);

What does appending "?v=1" to CSS and JavaScript URLs in link and script tags do?

This makes sure you are getting the latest version from of the css or js file from the server.

And later you can append "?v=2" if you have a newer version and "?v=3", "?v=4" and so on.

Note that you can use any querystring, 'v' is not a must for example:

"?blah=1" will work as well.

And

"?xyz=1002" will work.

And this is a common technique because browsers are now caching js and css files better and longer.

How to delete a specific line in a file?

here's some other method to remove a/some line(s) from a file:

src_file = zzzz.txt
f = open(src_file, "r")
contents = f.readlines()
f.close()

contents.pop(idx) # remove the line item from list, by line number, starts from 0

f = open(src_file, "w")
contents = "".join(contents)
f.write(contents)
f.close()

How to install a specific version of package using Composer?

As @alucic mentioned, use:

composer require vendor/package:version

or you can use:

composer update vendor/package:version

You should probably review this StackOverflow post about differences between composer install and composer update.

Related to question about version numbers, you can review Composer documentation on versions, but here in short:

  • Tilde Version Range (~) - ~1.2.3 is equivalent to >=1.2.3 <1.3.0
  • Caret Version Range (^) - ^1.2.3 is equivalent to >=1.2.3 <2.0.0

So, with Tilde you will get automatic updates of patches but minor and major versions will not be updated. However, if you use Caret you will get patches and minor versions, but you will not get major (breaking changes) versions.

Tilde Version is considered a "safer" approach, but if you are using reliable dependencies (well-maintained libraries) you should not have any problems with Caret Version (because minor changes should not be breaking changes.

What do I need to do to get Internet Explorer 8 to accept a self signed certificate?

You can use GPO to use the certificate within the domain.

But my problem is with Internet Explorer 8, that even with the certificate in the trusted root certification store... it still won't say it's a trusted site.

With this and the driver signing that needs to be done now... I'm starting to wonder who owns my computer!

How to use function srand() with time.h?

#include"stdio.h"
#include"conio.h"
#include"time.h"

void main()
{
  time_t t;
  int i;
  srand(time(&t));

  for(i=1;i<=10;i++)
    printf("%c\t",rand()%10);
  getch();
}

How to avoid Number Format Exception in java?

As always, the Jakarta Commons have at least part of the answer :

NumberUtils.isNumber()

This can be used to check most whether a given String is a number. You still have to choose what to do in case your String isnt a number ...

File size exceeds configured limit (2560000), code insight features not available

To clarify Alvaro's answer, you need to add the -D option to the list of command lines. I'm using PyCharm, but the concept is the same:

pycharm{64,.exe,64.exe}.vmoptions:
<code>
    -server
    -Xms128m
    ...
    -Didea.max.intellisense.filesize=999999 # <--- new line
</code>

How big can a MySQL database get before performance starts to degrade

It's kind of pointless to talk about "database performance", "query performance" is a better term here. And the answer is: it depends on the query, data that it operates on, indexes, hardware, etc. You can get an idea of how many rows are going to be scanned and what indexes are going to be used with EXPLAIN syntax.

2GB does not really count as a "large" database - it's more of a medium size.

onchange event on input type=range is not triggering in firefox while dragging

Yet another approach - just set a flag on an element signaling which type of event should be handled:

function setRangeValueChangeHandler(rangeElement, handler) {
    rangeElement.oninput = (event) => {
        handler(event);
        // Save flag that we are using onInput in current browser
        event.target.onInputHasBeenCalled = true;
    };

    rangeElement.onchange = (event) => {
        // Call only if we are not using onInput in current browser
        if (!event.target.onInputHasBeenCalled) {
            handler(event);
        }
    };
}

Laravel Eloquent - distinct() and count() not working properly together

$solution = $query->distinct()
            ->groupBy
            (
                [
                    'array',
                    'of',
                    'columns',
                ]
            )
            ->addSelect(
                [
                    'columns',
                    'from',
                    'the',
                    'groupby',
                ]
            )
            ->get();

Remember the group by is optional,this should work in most cases when you want a count group by to exclude duplicated select values, the addSelect is a querybuilder instance method.

What is CMake equivalent of 'configure --prefix=DIR && make all install '?

You can pass in any CMake variable on the command line, or edit cached variables using ccmake/cmake-gui. On the command line,

cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr . && make all install

Would configure the project, build all targets and install to the /usr prefix. The type (PATH) is not strictly necessary, but would cause the Qt based cmake-gui to present the directory chooser dialog.

Some minor additions as comments make it clear that providing a simple equivalence is not enough for some. Best practice would be to use an external build directory, i.e. not the source directly. Also to use more generic CMake syntax abstracting the generator.

mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr .. && cmake --build . --target install --config Release

You can see it gets quite a bit longer, and isn't directly equivalent anymore, but is closer to best practices in a fairly concise form... The --config is only used by multi-configuration generators (i.e. MSVC), ignored by others.

python numpy ValueError: operands could not be broadcast together with shapes

We might confuse ourselves that a * b is a dot product.

But in fact, it is broadcast.

Dot Product : a.dot(b)

Broadcast:

The term broadcasting refers to how numpy treats arrays with different dimensions during arithmetic operations which lead to certain constraints, the smaller array is broadcast across the larger array so that they have compatible shapes.

(m,n) +-/* (1,n) ? (m,n) : the operation will be applied to m rows

js 'types' can only be used in a .ts file - Visual Studio Code using @ts-check

You must use a .ts file - e.g. test.ts to get Typescript validation, intellisense typing of vars, return types, as well as "typed" error checking (e.g. passing a string to a method that expects an number param will error out).

It will be transpiled into (standard) .js via tsc.


Update (11/2018):

Clarification needed based on down-votes, very helpful comments and other answers.

types

  • Yes, you can do type checking in VS Code in .js files with @ts-check - as shown in the animation

  • What I originally was referring to for Typescript types is something like this in .ts which isn't quite the same thing:

    hello-world.ts

    function hello(str: string): string {
      return 1;
    }
    
    function foo(str:string):void{
       console.log(str);
    }
    

    This will not compile. Error: Type "1" is not assignable to String

  • if you tried this syntax in a Javascript hello-world.js file:

    //@ts-check
    
    function hello(str: string): string {
      return 1;
    }
    
    function foo(str:string):void{
       console.log(str);
    }
    

    The error message referenced by OP is shown: [js] 'types' can only be used in a .ts file

If there's something I missed that covers this as well as the OP's context, please add. Let's all learn.

In PHP, what is a closure and why does it use the "use" identifier?

Zupa did a great job explaining closures with 'use' and the difference between EarlyBinding and Referencing the variables that are 'used'.

So I made a code example with early binding of a variable (= copying):

<?php

$a = 1;
$b = 2;

$closureExampleEarlyBinding = function() use ($a, $b){
    $a++;
    $b++;
    echo "Inside \$closureExampleEarlyBinding() \$a = ".$a."<br />";
    echo "Inside \$closureExampleEarlyBinding() \$b = ".$b."<br />";    
};

echo "Before executing \$closureExampleEarlyBinding() \$a = ".$a."<br />";
echo "Before executing \$closureExampleEarlyBinding() \$b = ".$b."<br />";  

$closureExampleEarlyBinding();

echo "After executing \$closureExampleEarlyBinding() \$a = ".$a."<br />";
echo "After executing \$closureExampleEarlyBinding() \$b = ".$b."<br />";

/* this will output:
Before executing $closureExampleEarlyBinding() $a = 1
Before executing $closureExampleEarlyBinding() $b = 2
Inside $closureExampleEarlyBinding() $a = 2
Inside $closureExampleEarlyBinding() $b = 3
After executing $closureExampleEarlyBinding() $a = 1
After executing $closureExampleEarlyBinding() $b = 2
*/

?>

Example with referencing a variable (notice the '&' character before variable);

<?php

$a = 1;
$b = 2;

$closureExampleReferencing = function() use (&$a, &$b){
    $a++;
    $b++;
    echo "Inside \$closureExampleReferencing() \$a = ".$a."<br />";
    echo "Inside \$closureExampleReferencing() \$b = ".$b."<br />"; 
};

echo "Before executing \$closureExampleReferencing() \$a = ".$a."<br />";
echo "Before executing \$closureExampleReferencing() \$b = ".$b."<br />";   

$closureExampleReferencing();

echo "After executing \$closureExampleReferencing() \$a = ".$a."<br />";
echo "After executing \$closureExampleReferencing() \$b = ".$b."<br />";    

/* this will output:
Before executing $closureExampleReferencing() $a = 1
Before executing $closureExampleReferencing() $b = 2
Inside $closureExampleReferencing() $a = 2
Inside $closureExampleReferencing() $b = 3
After executing $closureExampleReferencing() $a = 2
After executing $closureExampleReferencing() $b = 3
*/

?>

How to parseInt in Angular.js

var app = angular.module('myApp', [])

app.controller('MainCtrl', ['$scope', function($scope){
   $scope.num1 = 1;
   $scope.num2 = 1;
   $scope.total = parseInt($scope.num1 + $scope.num2);

}]);

Demo: parseInt with AngularJS

jquery data selector

If you also use jQueryUI, you get a (simple) version of the :data selector with it that checks for the presence of a data item, so you can do something like $("div:data(view)"), or $( this ).closest(":data(view)").

See http://api.jqueryui.com/data-selector/ . I don't know for how long they've had it, but it's there now!

How to detect input type=file "change" for the same file?

You can trick it. Remove the file element and add it in the same place on change event. It will erase the file path making it changeable every time.

Example on jsFiddle.

Or you can simply use .prop("value", ""), see this example on jsFiddle.

  • jQuery 1.6+ prop
  • Earlier versions attr

Scrolling to an Anchor using Transition/CSS3

Just apply scroll behaviour to all elements with this one-line code:

_x000D_
_x000D_
*{
scroll-behavior: smooth !important;
}
_x000D_
_x000D_
_x000D_

IIS_IUSRS and IUSR permissions in IIS8

I hate to post my own answer, but some answers recently have ignored the solution I posted in my own question, suggesting approaches that are nothing short of foolhardy.

In short - you do not need to edit any Windows user account privileges at all. Doing so only introduces risk. The process is entirely managed in IIS using inherited privileges.

Applying Modify/Write Permissions to the Correct User Account

  1. Right-click the domain when it appears under the Sites list, and choose Edit Permissions

    enter image description here

    Under the Security tab, you will see MACHINE_NAME\IIS_IUSRS is listed. This means that IIS automatically has read-only permission on the directory (e.g. to run ASP.Net in the site). You do not need to edit this entry.

    enter image description here

  2. Click the Edit button, then Add...

  3. In the text box, type IIS AppPool\MyApplicationPoolName, substituting MyApplicationPoolName with your domain name or whatever application pool is accessing your site, e.g. IIS AppPool\mydomain.com

    enter image description here

  4. Press the Check Names button. The text you typed will transform (notice the underline):

    enter image description here

  5. Press OK to add the user

  6. With the new user (your domain) selected, now you can safely provide any Modify or Write permissions

    enter image description here

Entity Framework: There is already an open DataReader associated with this Command

A good middle-ground between enabling MARS and retrieving the entire result set into memory is to retrieve only IDs in an initial query, and then loop through the IDs materializing each entity as you go.

For example (using the "Blog and Posts" sample entities as in this answer):

using (var context = new BlogContext())
{
    // Get the IDs of all the items to loop through. This is
    // materialized so that the data reader is closed by the
    // time we're looping through the list.
    var blogIds = context.Blogs.Select(blog => blog.Id).ToList();

    // This query represents all our items in their full glory,
    // but, items are only materialized one at a time as we
    // loop through them.
    var blogs =
        blogIds.Select(id => context.Blogs.First(blog => blog.Id == id));

    foreach (var blog in blogs)
    {
        this.DoSomethingWith(blog.Posts);

        context.SaveChanges();
    }
}

Doing this means that you only pull a few thousand integers into memory, as opposed to thousands of entire object graphs, which should minimize memory usage while enabling you to work item-by-item without enabling MARS.

Another nice benefit of this, as seen in the sample, is that you can save changes as you loop through each item, instead of having to wait until the end of the loop (or some other such workaround), as would be needed even with MARS enabled (see here and here).

What is WEB-INF used for in a Java EE web application?

This convention is followed for security reasons. For example if unauthorized person is allowed to access root JSP file directly from URL then they can navigate through whole application without any authentication and they can access all the secured data.

WCF vs ASP.NET Web API

The new ASP.NET Web API is a continuation of the previous WCF Web API project (although some of the concepts have changed).

WCF was originally created to enable SOAP-based services. For simpler RESTful or RPCish services (think clients like jQuery) ASP.NET Web API should be good choice.


For us, WCF is used for SOAP and Web API for REST. I wish Web API supported SOAP too. We are not using advanced features of WCF. Here is comparison from MSDN:

enter image description here


ASP.net Web API is all about HTTP and REST based GET,POST,PUT,DELETE with well know ASP.net MVC style of programming and JSON returnable; web API is for all the light weight process and pure HTTP based components. For one to go ahead with WCF even for simple or simplest single web service it will bring all the extra baggage. For light weight simple service for ajax or dynamic calls always WebApi just solves the need. This neatly complements or helps in parallel to the ASP.net MVC.

Check out the podcast : Hanselminutes Podcast 264 - This is not your father's WCF - All about the WebAPI with Glenn Block by Scott Hanselman for more information.


In the scenarios listed below you should go for WCF:

  1. If you need to send data on protocols like TCP, MSMQ or MIME
  2. If the consuming client just knows how to consume SOAP messages

WEB API is a framework for developing RESTful/HTTP services.

There are so many clients that do not understand SOAP like Browsers, HTML5, in those cases WEB APIs are a good choice.

HTTP services header specifies how to secure service, how to cache the information, type of the message body and HTTP body can specify any type of content like HTML not just XML as SOAP services.

javascript remove "disabled" attribute from html input

Why not just remove that attribute?

  1. vanilla JS: elem.removeAttribute('disabled')
  2. jQuery: elem.removeAttr('disabled')

Location of sqlite database on the device

A SQLite database is just a file. You can take that file, move it around, and even copy it to another system (for example, from your phone to your workstation), and it will work fine. Android stores the file in the /data/data/packagename/databases/ directory. You can use the adb command or the File Explorer view in Eclipse (Window > Show View > Other... > Android > File Explorer) to view, move, or delete it.

How to extract hours and minutes from a datetime.datetime object?

datetime has fields hour and minute. So to get the hours and minutes, you would use t1.hour and t1.minute.

However, when you subtract two datetimes, the result is a timedelta, which only has the days and seconds fields. So you'll need to divide and multiply as necessary to get the numbers you need.

Redirect Windows cmd stdout and stderr to a single file

To add the stdout and stderr to the general logfile of a script:

dir >> a.txt 2>&1