SyntaxFix.com - Programming Questions & Answers Hub For Beginners


Some Of The Best Answers From Latest Asked Questions

Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED

I used ubuntu 12.04 I solved that problem by installing redis-server

redis-server installation for ubuntu 12.04

some configuration will new root permission Also listed manuals for other OS

Thanks

How to get exact browser name and version?

Use get_browser()

From Manual:

echo $_SERVER['HTTP_USER_AGENT'] . "\n\n";

$browser = get_browser(null, true);
print_r($browser);

Will return:

Array
(
    [browser_name_regex] => ^mozilla/5\.0 (windows; .; windows nt 5\.1; .*rv:.*) gecko/.* firefox/0\.9.*$
    [browser_name_pattern] => Mozilla/5.0 (Windows; ?; Windows NT 5.1; *rv:*) Gecko/* Firefox/0.9*/
    [parent] => Firefox 0.9
    [platform] => WinXP
    [browser] => Firefox
    [version] => 0.9
    [majorver] => 0
    [minorver] => 9
    [cssversion] => 2
    [frames] => 1
    [iframes] => 1
    [tables] => 1
    [cookies] => 1
    [backgroundsounds] =>
    [vbscript] =>
    [javascript] => 1
    [javaapplets] => 1
    [activexcontrols] =>
    [cdf] =>
    [aol] =>
    [beta] => 1
    [win16] =>
    [crawler] =>
    [stripper] =>
    [wap] =>
    [netclr] =>
)

Checking character length in ruby

I think you could just use the String#length method...

http://ruby-doc.org/core-1.9.3/String.html#method-i-length

Example:

text = 'The quick brown fox jumps over the lazy dog.'
puts text.length > 25 ? 'Too many characters' : 'Accepted'

How to insert data to MySQL having auto incremented primary key?

The default keyword works for me:

mysql> insert into user_table (user_id, ip, partial_ip, source, user_edit_date, username) values 
(default, '39.48.49.126', null, 'user signup page', now(), 'newUser');
---
Query OK, 1 row affected (0.00 sec)

I'm running mysql --version 5.1.66:

mysql  Ver 14.14 Distrib **5.1.66**, for debian-linux-gnu (x86_64) using readline 6.1

"Undefined reference to" template class constructor

You will have to define the functions inside your header file.
You cannot separate definition of template functions in to the source file and declarations in to header file.

When a template is used in a way that triggers its intstantation, a compiler needs to see that particular templates definition. This is the reason templates are often defined in the header file in which they are declared.

Reference:
C++03 standard, § 14.7.2.4:

The definition of a non-exported function template, a non-exported member function template, or a non-exported member function or static data member of a class template shall be present in every translation unit in which it is explicitly instantiated.

EDIT:
To clarify the discussion on the comments:
Technically, there are three ways to get around this linking problem:

  • To move the definition to the .h file
  • Add explicit instantiations in the .cpp file.
  • #include the .cpp file defining the template at the .cpp file using the template.

Each of them have their pros and cons,

Moving the defintions to header files may increase the code size(modern day compilers can avoid this) but will increase the compilation time for sure.

Using the explicit instantiation approach is moving back on to traditional macro like approach.Another disadvantage is that it is necessary to know which template types are needed by the program. For a simple program this is easy but for complicated program this becomes difficult to determine in advance.

While including cpp files is confusing at the same time shares the problems of both above approaches.

I find first method the easiest to follow and implement and hence advocte using it.

Working Copy Locked

Every time I get a Working copy locked error I run a "Clean up". After that everything is back to normal.

On the command line you can execute svn cleanup which also removes lock files.

Note: Perform this operation on one level up directory and that should resolve most of the times.

jQuery .live() vs .on() method for adding a click event after loading dynamic html

I know it's a little late for an answer, but I've created a polyfill for the .live() method. I've tested it in jQuery 1.11, and it seems to work pretty well. I know that we're supposed to implement the .on() method wherever possible, but in big projects, where it's not possible to convert all .live() calls to the equivalent .on() calls for whatever reason, the following might work:

if(jQuery && !jQuery.fn.live) {
    jQuery.fn.live = function(evt, func) {
        $('body').on(evt, this.selector, func);
    }
}

Just include it after you load jQuery and before you call live().

How to write a Unit Test?

I provide this post for both IntelliJ and Eclipse.

Eclipse:

For making unit test for your project, please follow these steps (I am using Eclipse in order to write this test):

1- Click on New -> Java Project.

Create Project

2- Write down your project name and click on finish.

Create Project

3- Right click on your project. Then, click on New -> Class.

Create Class

4- Write down your class name and click on finish.

Create Class

Then, complete the class like this:

public class Math {
    int a, b;
    Math(int a, int b) {
        this.a = a;
        this.b = b;
    }
    public int add() {
        return a + b;
    }
}

5- Click on File -> New -> JUnit Test Case.

Create JUnite Test

6- Check setUp() and click on finish. SetUp() will be the place that you initialize your test.

Check SetUp()

7- Click on OK.

Add JUnit

8- Here, I simply add 7 and 10. So, I expect the answer to be 17. Complete your test class like this:

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
public class MathTest {
    Math math;
    @Before
    public void setUp() throws Exception {
        math = new Math(7, 10);
    }
    @Test
    public void testAdd() {
        Assert.assertEquals(17, math.add());
    }
}

9- Write click on your test class in package explorer and click on Run as -> JUnit Test.

Run JUnit Test

10- This is the result of the test.

Result of The Test

IntelliJ: Note that I used IntelliJ IDEA community 2020.1 for the screenshots. Also, you need to set up your jre before these steps. I am using JDK 11.0.4.

1- Right-click on the main folder of your project-> new -> directory. You should call this 'test'. enter image description here 2- Right-click on the test folder and create the proper package. I suggest creating the same packaging names as the original class. Then, you right-click on the test directory -> mark directory as -> test sources root. enter image description here 3- In the right package in the test directory, you need to create a Java class (I suggest to use Test.java). enter image description here 4- In the created class, type '@Test'. Then, among the options that IntelliJ gives you, select Add 'JUnitx' to classpath. enter image description here enter image description here 5- Write your test method in your test class. The method signature is like:

@Test
public void test<name of original method>(){
...
}

You can do your assertions like below:

Assertions.assertTrue(f.flipEquiv(node1_1, node2_1));

These are the imports that I added:

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

enter image description here

This is the test that I wrote: enter image description here

You can check your methods like below:

Assertions.assertEquals(<Expected>,<actual>);
Assertions.assertTrue(<actual>);
...

For running your unit tests, right-click on the test and click on Run . enter image description here

If your test passes, the result will be like below: enter image description here

I hope it helps. You can see the structure of the project in GitHub https://github.com/m-vahidalizadeh/problem_solving_project.

How to get a pixel's x,y coordinate color from an image?

Canvas would be a great way to do this, as @pst said above. Check out this answer for a good example:

getPixel from HTML Canvas?

Some code that would serve you specifically as well:

var imgd = context.getImageData(x, y, width, height);
var pix = imgd.data;

for (var i = 0, n = pix.length; i < n; i += 4) {
  console.log pix[i+3]
}

This will go row by row, so you'd need to convert that into an x,y and either convert the for loop to a direct check or run a conditional inside.

Reading your question again, it looks like you want to be able to get the point that the person clicks on. This can be done pretty easily with jquery's click event. Just run the above code inside a click handler as such:

$('el').click(function(e){
   console.log(e.clientX, e.clientY)
}

Those should grab your x and y values.

How do I concatenate two text files in PowerShell?

Simply use the Get-Content and Set-Content cmdlets:

Get-Content inputFile1.txt, inputFile2.txt | Set-Content joinedFile.txt

You can concatenate more than two files with this style, too.

If the source files are named similarly, you can use wildcards:

Get-Content inputFile*.txt | Set-Content joinedFile.txt

Note 1: PowerShell 5 and older versions allowed this to be done more concisely using the aliases cat and sc for Get-Content and Set-Content respectively. However, these aliases are problematic because cat is a system command in *nix systems, and sc is a system command in Windows systems - therefore using them is not recommended, and in fact sc is no longer even defined as of PowerShell Core (v7). The PowerShell team recommends against using aliases in general.

Note 2: Be careful with wildcards - if you try to output to examples.txt (or similar that matches the pattern), PowerShell will get into an infinite loop! (I just tested this.)

Note 3: Outputting to a file with > does not preserve character encoding! This is why using Set-Content is recommended.

How to find out what is locking my tables?

For getting straight to "who is blocked/blocking" I combined/abbreviated sp_who and sp_lock into a single query which gives a nice overview of who has what object locked to what level.

--Create Procedure WhoLock
--AS
set nocount on
if object_id('tempdb..#locksummary') is not null Drop table #locksummary
if object_id('tempdb..#lock') is not null Drop table #lock
create table #lock (    spid int,    dbid int,    objId int,    indId int,    Type char(4),    resource nchar(32),    Mode char(8),    status char(6))
Insert into #lock exec sp_lock
if object_id('tempdb..#who') is not null Drop table #who
create table #who (     spid int, ecid int, status char(30),
            loginame char(128), hostname char(128),
            blk char(5), dbname char(128), cmd char(16)
            --
            , request_id INT --Needed for SQL 2008 onwards
            --
         )
Insert into #who exec sp_who
Print '-----------------------------------------'
Print 'Lock Summary for ' + @@servername  + ' (excluding tempdb):'
Print '-----------------------------------------' + Char(10)
Select     left(loginame, 28) as loginame, 
    left(db_name(dbid),128) as DB,
    left(object_name(objID),30) as object,
    max(mode) as [ToLevel],
    Count(*) as [How Many],
    Max(Case When mode= 'X' Then cmd Else null End) as [Xclusive lock for command],
    l.spid, hostname
into #LockSummary
from #lock l join #who w on l.spid= w.spid
where dbID != db_id('tempdb') and l.status='GRANT'
group by dbID, objID, l.spid, hostname, loginame

Select * from #LockSummary order by [ToLevel] Desc, [How Many] Desc, loginame, DB, object

Print '--------'
Print 'Who is blocking:'
Print '--------' + char(10)
SELECT p.spid
,convert(char(12), d.name) db_name
, program_name
, p.loginame
, convert(char(12), hostname) hostname
, cmd
, p.status
, p.blocked
, login_time
, last_batch
, p.spid
FROM      master..sysprocesses p
JOIN      master..sysdatabases d ON p.dbid =  d.dbid
WHERE     EXISTS (  SELECT 1
          FROM      master..sysprocesses p2
          WHERE     p2.blocked = p.spid )

Print '--------'
Print 'Details:'
Print '--------' + char(10)
Select     left(loginame, 30) as loginame,  l.spid,
    left(db_name(dbid),15) as DB,
    left(object_name(objID),40) as object,
    mode ,
    blk,
    l.status
from #lock l join #who w on l.spid= w.spid
where dbID != db_id('tempdb') and blk <>0
Order by mode desc, blk, loginame, dbID, objID, l.status

(For what the lock level abbreviations mean, see e.g. https://technet.microsoft.com/en-us/library/ms175519%28v=sql.105%29.aspx)

Copied from: sp_WhoLock – a T-SQL stored proc combining sp_who and sp_lock...

NB the [Xclusive lock for command] column can be misleading -- it shows the current command for that spid; but the X lock could have been triggered by an earlier command in the transaction.

Create table with jQuery - append

When you use append, jQuery expects it to be well-formed HTML (plain text counts). append is not like doing +=.

You need to make the table first, then append it.

var $table = $('<table/>');
for(var i=0; i<3; i++){
    $table.append( '<tr><td>' + 'result' +  i + '</td></tr>' );
}
$('#here_table').append($table);

When do we need curly braces around shell variables?

Following SierraX and Peter's suggestion about text manipulation, curly brackets {} are used to pass a variable to a command, for instance:

Let's say you have a sposi.txt file containing the first line of a well-known Italian novel:

> sposi="somewhere/myfolder/sposi.txt"
> cat $sposi

Ouput: quel ramo del lago di como che volge a mezzogiorno

Now create two variables:

# Search the 2nd word found in the file that "sposi" variable points to
> word=$(cat $sposi | cut -d " " -f 2)

# This variable will replace the word
> new_word="filone"

Now substitute the word variable content with the one of new_word, inside sposi.txt file

> sed -i "s/${word}/${new_word}/g" $sposi
> cat $sposi

Ouput: quel filone del lago di como che volge a mezzogiorno

The word "ramo" has been replaced.

Detecting value change of input[type=text] in jQuery

Use this: https://github.com/gilamran/JQuery-Plugin-AnyChange

It handles all the ways to change the input, including content menu (Using the mouse)

'Operation is not valid due to the current state of the object' error during postback

I didn't apply paging on my gridview and it extends to more than 600 records (with checkbox, buttons, etc.) and the value of 2001 didn't work. You may increase the value, say 10000 and test.

<appSettings>
<add key="aspnet:MaxHttpCollectionKeys" value="10000" />
</appSettings>

How to get selected value from Dropdown list in JavaScript

According to Html5 specs you should use -- element.options[e.selectedIndex].text

e.g. if you have select box like below :

<select id="selectbox1">
    <option value="1">First</option>
    <option value="2" selected="selected">Second</option>
    <option value="3">Third</option>
</select>
<br/>
<button onClick="GetItemValue('selectbox1');">Get Item</button>

you can get value using following script :

<script>
 function GetItemValue(q) {
   var e = document.getElementById(q);
   var selValue = e.options[e.selectedIndex].text ;
   alert("Selected Value: "+selValue);
 }
</script>

Tried and tested.

MySQL Workbench: "Can't connect to MySQL server on 127.0.0.1' (10061)" error

Try placing the host name (db01.mysql.vm.MyHostingServer.net) in your windows host (C:\windows\system32\drivers\etc\host) file along with it's IP address and port number and see if that helps.

Where can I get Google developer key

First activate Google+ API, then you will get "Simple API access" box, from there you can get developer key as API key https://code.google.com/apis/console/?api=plus or read this: http://code.google.com/p/google-api-php-client/wiki/OAuth2

Android, How to read QR code in my application?

if user doesn't have any qr reader, what will happen to the application? if it crashes, may i ask user to download for example QrDroid and after that use it?

Interestingly, Google now introduced Mobile Vision APIs, they are integrated in play services itself.

In your Gradle file just add:

compile 'com.google.android.gms:play-services-vision:11.4.0'

Taken from this QR code tutorial.

UPDATE 2020:

Now QR code scanning is also a part of ML Kit, so you can bundle the model inside the app and use it by integrating the following gradle dependency:

dependencies {
  // ...
  // Use this dependency to bundle the model with your app
  implementation 'com.google.mlkit:barcode-scanning:16.0.3'
}

Or you can use the following gradle dependency to dynamically download the models from Google Play Services:

dependencies {
  // ...
  // Use this dependency to use the dynamically downloaded model in Google Play Services
  implementation 'com.google.android.gms:play-services-mlkit-barcode-scanning:16.1.2'
}

Taken from this link.

JavaScript DOM remove element

Seems I don't have enough rep to post a comment, so another answer will have to do.

When you unlink a node using removeChild() or by setting the innerHTML property on the parent, you also need to make sure that there is nothing else referencing it otherwise it won't actually be destroyed and will lead to a memory leak. There are lots of ways in which you could have taken a reference to the node before calling removeChild() and you have to make sure those references that have not gone out of scope are explicitly removed.

Doug Crockford writes here that event handlers are known a cause of circular references in IE and suggests removing them explicitly as follows before calling removeChild()

function purge(d) {
    var a = d.attributes, i, l, n;
    if (a) {
        for (i = a.length - 1; i >= 0; i -= 1) {
            n = a[i].name;
            if (typeof d[n] === 'function') {
                d[n] = null;
            }
        }
    }
    a = d.childNodes;
    if (a) {
        l = a.length;
        for (i = 0; i < l; i += 1) {
            purge(d.childNodes[i]);
        }
    }
}

And even if you take a lot of precautions you can still get memory leaks in IE as described by Jens-Ingo Farley here.

And finally, don't fall into the trap of thinking that Javascript delete is the answer. It seems to be suggested by many, but won't do the job. Here is a great reference on understanding delete by Kangax.

PHP convert XML to JSON

I guess I'm a bit late to the party but I have written a small function to accomplish this task. It also takes care of attributes, text content and even if multiple nodes with the same node-name are siblings.

Dislaimer: I'm not a PHP native, so please bear with simple mistakes.

function xml2js($xmlnode) {
    $root = (func_num_args() > 1 ? false : true);
    $jsnode = array();

    if (!$root) {
        if (count($xmlnode->attributes()) > 0){
            $jsnode["$"] = array();
            foreach($xmlnode->attributes() as $key => $value)
                $jsnode["$"][$key] = (string)$value;
        }

        $textcontent = trim((string)$xmlnode);
        if (count($textcontent) > 0)
            $jsnode["_"] = $textcontent;

        foreach ($xmlnode->children() as $childxmlnode) {
            $childname = $childxmlnode->getName();
            if (!array_key_exists($childname, $jsnode))
                $jsnode[$childname] = array();
            array_push($jsnode[$childname], xml2js($childxmlnode, true));
        }
        return $jsnode;
    } else {
        $nodename = $xmlnode->getName();
        $jsnode[$nodename] = array();
        array_push($jsnode[$nodename], xml2js($xmlnode, true));
        return json_encode($jsnode);
    }
}   

Usage example:

$xml = simplexml_load_file("myfile.xml");
echo xml2js($xml);

Example Input (myfile.xml):

<family name="Johnson">
    <child name="John" age="5">
        <toy status="old">Trooper</toy>
        <toy status="old">Ultrablock</toy>
        <toy status="new">Bike</toy>
    </child>
</family>

Example output:

{"family":[{"$":{"name":"Johnson"},"child":[{"$":{"name":"John","age":"5"},"toy":[{"$":{"status":"old"},"_":"Trooper"},{"$":{"status":"old"},"_":"Ultrablock"},{"$":{"status":"new"},"_":"Bike"}]}]}]}

Pretty printed:

{
    "family" : [{
            "$" : {
                "name" : "Johnson"
            },
            "child" : [{
                    "$" : {
                        "name" : "John",
                        "age" : "5"
                    },
                    "toy" : [{
                            "$" : {
                                "status" : "old"
                            },
                            "_" : "Trooper"
                        }, {
                            "$" : {
                                "status" : "old"
                            },
                            "_" : "Ultrablock"
                        }, {
                            "$" : {
                                "status" : "new"
                            },
                            "_" : "Bike"
                        }
                    ]
                }
            ]
        }
    ]
}

Quirks to keep in mind: Several tags with the same tagname can be siblings. Other solutions will most likely drop all but the last sibling. To avoid this each and every single node, even if it only has one child, is an array which hold an object for each instance of the tagname. (See multiple "" elements in example)

Even the root element, of which only one should exist in a valid XML document is stored as array with an object of the instance, just to have a consistent data structure.

To be able to distinguish between XML node content and XML attributes each objects attributes are stored in the "$" and the content in the "_" child.

Edit: I forgot to show the output for your example input data

{
    "states" : [{
            "state" : [{
                    "$" : {
                        "id" : "AL"
                    },
                    "name" : [{
                            "_" : "Alabama"
                        }
                    ]
                }, {
                    "$" : {
                        "id" : "AK"
                    },
                    "name" : [{
                            "_" : "Alaska"
                        }
                    ]
                }
            ]
        }
    ]
}

Get current category ID of the active page

If it is a category page,you can get id of current category by:

$category = get_category( get_query_var( 'cat' ) );
$cat_id = $category->cat_ID;

If you want to get category id of any particular category on any page, try using :

$category_id = get_cat_ID('Category Name');

Elasticsearch query to return all records

elasticsearch(ES) supports both a GET or a POST request for getting the data from the ES cluster index.

When we do a GET:

http://localhost:9200/[your index name]/_search?size=[no of records you want]&q=*:*

When we do a POST:

http://localhost:9200/[your_index_name]/_search
{
  "size": [your value] //default 10
  "from": [your start index] //default 0
  "query":
   {
    "match_all": {}
   }
}   

I would suggest to use a UI plugin with elasticsearch http://mobz.github.io/elasticsearch-head/ This will help you get a better feeling of the indices you create and also test your indices.

Check if table exists without using "select from"

Here is a table that is not a SELECT * FROM

SHOW TABLES FROM `db` LIKE 'tablename'; //zero rows = not exist

Got this from a database pro, here is what I was told:

select 1 from `tablename`; //avoids a function call
select * from INFORMATION_SCHEMA.tables where schema = 'db' and table = 'table' // slow. Field names not accurate
SHOW TABLES FROM `db` LIKE 'tablename'; //zero rows = does not exist

Changing the maximum length of a varchar column?

I was also having above doubt, what worked for me is

ALTER TABLE `your_table` CHANGE `property` `property` 
VARCHAR(whatever_you_want) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL;  

Get GPS location via a service in Android

I don't understand what exactly is the problem with implementing location listening functionality in the Service. It looks pretty similar to what you do in Activity. Just define a location listener and register for location updates. You can refer to the following code as example:

Manifest file:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity android:label="@string/app_name" android:name=".LocationCheckerActivity" >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <service android:name=".MyService" android:process=":my_service" />
</application>

The service file:

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;

public class MyService extends Service {

    private static final String TAG = "BOOMBOOMTESTGPS";
    private LocationManager mLocationManager = null;
    private static final int LOCATION_INTERVAL = 1000;
    private static final float LOCATION_DISTANCE = 10f;

    private class LocationListener implements android.location.LocationListener {
        Location mLastLocation;

        public LocationListener(String provider) {
            Log.e(TAG, "LocationListener " + provider);
            mLastLocation = new Location(provider);
        }

        @Override
        public void onLocationChanged(Location location) {
            Log.e(TAG, "onLocationChanged: " + location);
            mLastLocation.set(location);
        }

        @Override
        public void onProviderDisabled(String provider) {
            Log.e(TAG, "onProviderDisabled: " + provider);
        }

        @Override
        public void onProviderEnabled(String provider) {
            Log.e(TAG, "onProviderEnabled: " + provider);
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            Log.e(TAG, "onStatusChanged: " + provider);
        }
    }

    LocationListener[] mLocationListeners = new LocationListener[]{
            new LocationListener(LocationManager.GPS_PROVIDER),
            new LocationListener(LocationManager.NETWORK_PROVIDER)
    };

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.e(TAG, "onStartCommand");
        super.onStartCommand(intent, flags, startId);
        return START_STICKY;
    }

    @Override
    public void onCreate() {
        Log.e(TAG, "onCreate");
        initializeLocationManager();
        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER, LOCATION_INTERVAL, LOCATION_DISTANCE,
                    mLocationListeners[1]);
        } catch (java.lang.SecurityException ex) {
            Log.i(TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "network provider does not exist, " + ex.getMessage());
        }
        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.GPS_PROVIDER, LOCATION_INTERVAL, LOCATION_DISTANCE,
                    mLocationListeners[0]);
        } catch (java.lang.SecurityException ex) {
            Log.i(TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(TAG, "gps provider does not exist " + ex.getMessage());
        }
    }

    @Override
    public void onDestroy() {
        Log.e(TAG, "onDestroy");
        super.onDestroy();
        if (mLocationManager != null) {
            for (int i = 0; i < mLocationListeners.length; i++) {
                try {
                    mLocationManager.removeUpdates(mLocationListeners[i]);
                } catch (Exception ex) {
                    Log.i(TAG, "fail to remove location listners, ignore", ex);
                }
            }
        }
    }

    private void initializeLocationManager() {
        Log.e(TAG, "initializeLocationManager");
        if (mLocationManager == null) {
            mLocationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
        }
    }
}

Hadoop: «ERROR : JAVA_HOME is not set»

I tried the above solutions but the following worked on me

export JAVA_HOME=/usr/java/default

matplotlib savefig in jpeg format

I just updated matplotlib to 1.1.0 on my system and it now allows me to save to jpg with savefig.

To upgrade to matplotlib 1.1.0 with pip, use this command:

pip install -U 'http://sourceforge.net/projects/matplotlib/files/matplotlib/matplotlib-1.1.0/matplotlib-1.1.0.tar.gz/download'

EDIT (to respond to comment):

pylab is simply an aggregation of the matplotlib.pyplot and numpy namespaces (as well as a few others) jinto a single namespace.

On my system, pylab is just this:

from matplotlib.pylab import *
import matplotlib.pylab
__doc__ = matplotlib.pylab.__doc__

You can see that pylab is just another namespace in your matplotlib installation. Therefore, it doesn't matter whether or not you import it with pylab or with matplotlib.pyplot.

If you are still running into problem, then I'm guessing the macosx backend doesn't support saving plots to jpg. You could try using a different backend. See here for more information.

Maven Install on Mac OS X

% sudo port selfupdate; 
% sudo port upgrade outdated;
% sudo port install maven3;
% sudo port select --set maven maven3;

— add following to .zshenv -- start using zsh if you dont —
set -a
[[ -d /opt/local/share/java/maven3 ]] &&
    M3_HOME=/opt/local/share/java/maven3 &&
    M2_HOME=/opt/local/share/java/maven3 &&
    MAVEN_OPTS="-Xmx1024m" &&
    M2=${M2_HOME}/bin
set +a

Include files from parent or other directory

Had same issue earlier solved like this :

include('/../includes/config.php'); //note '/' appearing before '../includes/config.php'

How to convert HH:mm:ss.SSS to milliseconds?

If you want to use SimpleDateFormat, you could write:

private final SimpleDateFormat sdf =
    new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
    { sdf.setTimeZone(TimeZone.getTimeZone("GMT")); }

private long parseTimeToMillis(final String time) throws ParseException
    { return sdf.parse("1970-01-01 " + time).getTime(); }

But a custom method would be much more efficient. SimpleDateFormat, because of all its calendar support, time-zone support, daylight-savings-time support, and so on, is pretty slow. The slowness is worth it if you actually need some of those features, but since you don't, it might not be. (It depends how often you're calling this method, and whether efficiency is a concern for your application.)

Also, SimpleDateFormat is non-thread-safe, which is sometimes a pain. (Without knowing anything about your application, I can't guess whether that matters.)

Personally, I'd probably write a custom method.

Using ResourceManager

The quick and dirty way to check what string you need it to look at the generated .resources files.

Your .resources are generated in the resources projects obj/Debug directory. (if not right click on .resx file in solution explorer and hit 'Run Custom Tool' to generate the .resources files)

Navigate to this directory and have a look at the filenames. You should see a file ending in XYZ.resources. Copy that filename and remove the trailing .resources and that is the file you should be loading.

For example in my obj/Bin directory I have the file:

MyLocalisation.Properties.Resources.resources

If the resource files are in the same Class library/Application I would use the following C#

ResourceManager RM = new ResourceManager("MyLocalisation.Properties.Resources", Assembly.GetExecutingAssembly());

However, as it sounds like you are using the resources file from a separate Class library/Application you probably want

Assembly localisationAssembly = Assembly.Load("MyLocalisation");
ResourceManager RM =  new ResourceManager("MyLocalisation.Properties.Resources", localisationAssembly);

How do I detect whether 32-bit Java is installed on x64 Windows, only looking at the filesystem and registry?

This seems to provide the info on Windows:

1.) Open a windows command prompt.

2.) Key in: java -XshowSettings:all and hit ENTER.

3.) A lot of information will be displayed on the command window. Scroll up until you find the string: sun.arch.data.model.

4.) If it says sun.arch.data.model = 32, your VM is 32 bit. If it says sun.arch.data.model = 64, your VM is 64 bit.

How to amend older Git commit?

I prepared my commit that I wanted to amend with an older one and was surprised to see that rebase -i complained that I have uncommitted changes. But I didn't want to make my changes again specifying edit option of the older commit. So the solution was pretty easy and straightforward:

  1. prepare your update to older commit, add it and commit
  2. git rebase -i <commit you want to amend>^ - notice the ^ so you see the said commit in the text editor
  3. you will get sometihng like this:

    pick 8c83e24 use substitution instead of separate subsystems file to avoid jgroups.xml and jgroups-e2.xml going out of sync
    pick 799ce28 generate ec2 configuration out of subsystems-ha.xml and subsystems-full-ha.xml to avoid discrepancies
    pick e23d23a fix indentation of jgroups.xml
    
  4. now to combine e23d23a with 8c83e24 you can change line order and use squash like this:

    pick 8c83e24 use substitution instead of separate subsystems file to avoid jgroups.xml and jgroups-e2.xml going out of sync    
    squash e23d23a fix indentation of jgroups.xml
    pick 799ce28 generate ec2 configuration out of subsystems-ha.xml and subsystems-full-ha.xml to avoid discrepancies
    
  5. write and exit the file, you will be present with an editor to merge the commit messages. Do so and save/exit the text document

  6. You are done, your commits are amended

credit goes to: http://git-scm.com/book/en/Git-Tools-Rewriting-History There's also other useful demonstrated git magic.

Make div stay at bottom of page's content all the time even when there are scrollbars

Unfortunately you can't do this with out adding a little extra HTML and having one piece of CSS rely on another.

HTML

First you need to wrap your header,footer and #body into a #holder div:

<div id="holder">
    <header>.....</header>
    <div id="body">....</div>
    <footer>....</footer>
</div>

CSS

Then set height: 100% to html and body (actual body, not your #body div) to ensure you can set minimum height as a percentage on child elements.

Now set min-height: 100% on the #holder div so it fills the content of the screen and use position: absolute to sit the footer at the bottom of the #holder div.

Unfortunately, you have to apply padding-bottom to the #body div that is the same height as the footer to ensure that the footer does not sit above any content:

html,body{
    height: 100%
}

#holder{
    min-height: 100%;
    position:relative;
}

#body{
    padding-bottom: 100px;    /* height of footer */
}

footer{
    height: 100px; 
    width:100%;
    position: absolute;
    left: 0;
    bottom: 0; 
}

Working example, short body: http://jsfiddle.net/ELUGc/

Working example, long body: http://jsfiddle.net/ELUGc/1/

What is the purpose of the "final" keyword in C++11 for functions?

Nothing to add to the semantic aspects of "final".

But I'd like to add to chris green's comment that "final" might become a very important compiler optimization technique in the not so distant future. Not only in the simple case he mentioned, but also for more complex real-world class hierarchies which can be "closed" by "final", thus allowing compilers to generate more efficient dispatching code than with the usual vtable approach.

One key disadvantage of vtables is that for any such virtual object (assuming 64-bits on a typical Intel CPU) the pointer alone eats up 25% (8 of 64 bytes) of a cache line. In the kind of applications I enjoy to write, this hurts very badly. (And from my experience it is the #1 argument against C++ from a purist performance point of view, i.e. by C programmers.)

In applications which require extreme performance, which is not so unusual for C++, this might indeed become awesome, not requiring to workaround this problem manually in C style or weird Template juggling.

This technique is known as Devirtualization. A term worth remembering. :-)

There is a great recent speech by Andrei Alexandrescu which pretty well explains how you can workaround such situations today and how "final" might be part of solving similar cases "automatically" in the future (discussed with listeners):

http://channel9.msdn.com/Events/GoingNative/2013/Writing-Quick-Code-in-Cpp-Quickly

How to redirect from one URL to another URL?

window.location.href = "URL2"

inside a JS block on the page or in an included file; that's assuming you really want to do it on the client. Usually, the server sends the redirect via a 300-series response.

How to return an array from an AJAX call?

Have a look at json_encode() in PHP. You can get $.ajax to recognize this with the dataType: "json" parameter.

Echo off but messages are displayed

As Mike Nakis said, echo off only prevents the printing of commands, not results. To hide the result of a command add >nul to the end of the line, and to hide errors add 2>nul. For example:

Del /Q *.tmp >nul 2>nul

Like Krister Andersson said, the reason you get an error is your variable is expanding with spaces:

set INSTALL_PATH=C:\My App\Installer
if exist %INSTALL_PATH% (

Becomes:

if exist C:\My App\Installer (

Which means:

If "C:\My" exists, run "App\Installer" with "(" as the command line argument.

You see the error because you have no folder named "App". Put quotes around the path to prevent this splitting.

What do the python file extensions, .pyc .pyd .pyo stand for?

  • .py - Regular script
  • .py3 - (rarely used) Python3 script. Python3 scripts usually end with ".py" not ".py3", but I have seen that a few times
  • .pyc - compiled script (Bytecode)
  • .pyo - optimized pyc file (As of Python3.5, Python will only use pyc rather than pyo and pyc)
  • .pyw - Python script to run in Windowed mode, without a console; executed with pythonw.exe
  • .pyx - Cython src to be converted to C/C++
  • .pyd - Python script made as a Windows DLL
  • .pxd - Cython script which is equivalent to a C/C++ header
  • .pxi - MyPy stub
  • .pyi - Stub file (PEP 484)
  • .pyz - Python script archive (PEP 441); this is a script containing compressed Python scripts (ZIP) in binary form after the standard Python script header
  • .pywz - Python script archive for MS-Windows (PEP 441); this is a script containing compressed Python scripts (ZIP) in binary form after the standard Python script header
  • .py[cod] - wildcard notation in ".gitignore" that means the file may be ".pyc", ".pyo", or ".pyd".
  • .pth - a path configuration file; its contents are additional items (one per line) to be added to sys.path. See site module.

A larger list of additional Python file-extensions (mostly rare and unofficial) can be found at http://dcjtech.info/topic/python-file-extensions/

How to replace a whole line with sed?

Like this:

sed 's/aaa=.*/aaa=xxx/'

If you want to guarantee that the aaa= is at the start of the line, make it:

sed 's/^aaa=.*/aaa=xxx/'

Why is access to the path denied?

I had the exact error when deleting a file. It was a Windows Service running under a Service Account which was unable to delete a .pdf document from a Shared Folder even though it had Full Control of the folder.

What worked for me was navigating to the Security tab of the Shared Folder > Advanced > Share > Add.

I then added the service account to the administrators group, applied the changes and the service account was then able to perform all operations on all files within that folder.

Get access to parent control from user control - C#

You can get the Parent of a control via

myControl.Parent

See MSDN: Control.Parent

How do I remove a specific element from a JSONArray?

Try this code

ArrayList<String> list = new ArrayList<String>();     
JSONArray jsonArray = (JSONArray)jsonObject; 
int len = jsonArray.length();
if (jsonArray != null) { 
   for (int i=0;i<len;i++){ 
    list.add(jsonArray.get(i).toString());
   } 
}
//Remove the element from arraylist
list.remove(position);
//Recreate JSON Array
JSONArray jsArray = new JSONArray(list);

Edit: Using ArrayList will add "\" to the key and values. So, use JSONArray itself

JSONArray list = new JSONArray();     
JSONArray jsonArray = new JSONArray(jsonstring); 
int len = jsonArray.length();
if (jsonArray != null) { 
   for (int i=0;i<len;i++)
   { 
       //Excluding the item at position
        if (i != position) 
        {
            list.put(jsonArray.get(i));
        }
   } 
}

Best way to Format a Double value to 2 Decimal places

An alternative is to use String.format:

double[] arr = { 23.59004,
    35.7,
    3.0,
    9
};

for ( double dub : arr ) {
  System.out.println( String.format( "%.2f", dub ) );
}

output:

23.59
35.70
3.00
9.00

You could also use System.out.format (same method signature), or create a java.util.Formatter which works in the same way.

How do I connect to a specific Wi-Fi network in Android programmatically?

I broke my head to understand why your answers for WPA/WPA2 don't work...after hours of tries I found what you are missing:

conf.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN);

is REQUIRED for WPA networks!!!!

Now, it works :)

How to search a string in a single column (A) in excel using VBA

Below are two methods that are superior to looping. Both handle a "no-find" case.

  1. The VBA equivalent of a normal function VLOOKUP with error-handling if the variable doesn't exist (INDEX/MATCH may be a better route than VLOOKUP, ie if your two columns A and B were in reverse order, or were far apart)
  2. VBAs FIND method (matching a whole string in column A given I use the xlWhole argument)

    Sub Method1()
    Dim strSearch As String
    Dim strOut As String
    Dim bFailed As Boolean
    
    strSearch = "trees"
    
    On Error Resume Next
    strOut = Application.WorksheetFunction.VLookup(strSearch, Range("A:B"), 2, False)
    If Err.Number <> 0 Then bFailed = True
    On Error GoTo 0
    
    If Not bFailed Then
    MsgBox "corresponding value is " & vbNewLine & strOut
    Else
    MsgBox strSearch & " not found"
    End If
    End Sub
    
    Sub Method2()
        Dim rng1 As Range
        Dim strSearch As String
        strSearch = "trees"
        Set rng1 = Range("A:A").Find(strSearch, , xlValues, xlWhole)
        If Not rng1 Is Nothing Then
            MsgBox "Find has matched " & strSearch & vbNewLine & "corresponding cell is " & rng1.Offset(0, 1)
        Else
            MsgBox strSearch & " not found"
        End If
    End Sub
    

How can I run a function from a script in command line?

I have a situation where I need a function from bash script which must not be executed before (e.g. by source) and the problem with @$ is that myScript.sh is then run twice, it seems... So I've come up with the idea to get the function out with sed:

sed -n "/^func ()/,/^}/p" myScript.sh

And to execute it at the time I need it, I put it in a file and use source:

sed -n "/^func ()/,/^}/p" myScript.sh > func.sh; source func.sh; rm func.sh

How to create the pom.xml for a Java project with Eclipse

To create pom.xml file follow the next steps:

  1. Right click on the current project
  2. Select Configure option
  3. Select Convert to Maven Project
  4. Complete all fields in Create new POM window
  5. Check "Delete original references from project"
  6. Click on Finish button

If eclipse show the the error "Maven error “Failure to transfer…", follow the next steps

  1. Copy the dependency to pom.

    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-archiver</artifactId>
        <version>2.5</version>
    </dependency>
    
  2. Click right on your project

  3. Select Maven
  4. Select Update project
  5. Select Force Update of Snapshots/Releases

How to make sure that a certain Port is not occupied by any other process

It's (Get-NetTCPConnection -LocalPort "port no.").OwningProcess

Why is __dirname not defined in node REPL?

I was also trying to join my path using path.join(__dirname, 'access.log') but it was throwing the same error.

Here is how I fixed it:

I first imported the path package and declared a variable named __dirname, then called the resolve path method.

In CommonJS

var path = require("path");

var __dirname = path.resolve();

In ES6+

import path  from 'path';

const __dirname = path.resolve();

Happy coding.......

Sharing url link does not show thumbnail image on facebook

My site faces same issue too.

Using Facebook debug tool is no help at all. Fetch new data but not IMAGE CACHE.

I forced facebook to clear IMAGE CACHE by add www. into image url. In your case is remove www. and config web server redirect.

 add/remove www. in image url should solve the problem

How can I retrieve the remote git address of a repo?

When you want to show an URL of remote branches, try:

git remote -v

Why is Thread.Sleep so harmful

For those of you who hasn't seen one valid argument against use of Thread.Sleep in SCENARIO 2, there really is one - application exit be held up by the while loop (SCENARIO 1/3 is just plain stupid so not worthy of more mentioning)

Many who pretend to be in-the-know, screaming Thread.Sleep is evil failed to mentioned a single valid reason for those of us who demanded a practical reason not to use it - but here it is, thanks to Pete - Thread.Sleep is Evil (can be easily avoided with a timer/handler)

    static void Main(string[] args)
    {
        Thread t = new Thread(new ThreadStart(ThreadFunc));
        t.Start();

        Console.WriteLine("Hit any key to exit.");
        Console.ReadLine();

        Console.WriteLine("App exiting");
        return;
    }

    static void ThreadFunc()
    {
        int i=0;
        try
        {
            while (true)
            {
                Console.WriteLine(Thread.CurrentThread.ThreadState.ToString() + " " + i);

                Thread.Sleep(1000 * 10);
                i++;
            }
        }
        finally
        {
            Console.WriteLine("Exiting while loop");
        }
        return;
    }

Convert bytes to bits in python

Another way to do this is by using the bitstring module:

>>> from bitstring import BitArray
>>> input_str = '0xff'
>>> c = BitArray(hex=input_str)
>>> c.bin
'0b11111111'

And if you need to strip the leading 0b:

>>> c.bin[2:]
'11111111'

The bitstring module isn't a requirement, as jcollado's answer shows, but it has lots of performant methods for turning input into bits and manipulating them. You might find this handy (or not), for example:

>>> c.uint
255
>>> c.invert()
>>> c.bin[2:]
'00000000'

etc.

receiver type *** for instance message is a forward declaration

FWIW, I got this error when I was implementing core data in to an existing project. It turned out I forgot to link CoreData.h to my project. I had already added the CoreData framework to my project but solved the issue by linking to the framework in my pre-compiled header just like Apple's templates do:

#import <Availability.h>

#ifndef __IPHONE_5_0
#warning "This project uses features only available in iOS SDK 5.0 and later."
#endif

#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    #import <CoreData/CoreData.h>
#endif

Remove blank values from array using C#

I prefer to use two options, white spaces and empty:

test = test.Where(x => !string.IsNullOrEmpty(x)).ToArray();
test = test.Where(x => !string.IsNullOrWhiteSpace(x)).ToArray();

python: [Errno 10054] An existing connection was forcibly closed by the remote host

there are many causes such as

  • The network link between server and client may be temporarily going down.
  • running out of system resources.
  • sending malformed data.

To examine the problem in detail, you can use Wireshark.

or you can just re-request or re-connect again.

How to make an HTML back link?

The best way using a button is

<input type= 'button' onclick='javascript:history.back();return false;' value='Back'>

Properly close mongoose's connection once you're done

The other answer didn't work for me. I had to use mongoose.disconnect(); as stated in this answer.

javascript popup alert on link click

You can use the onclick attribute, just return false if you don't want continue;

<script type="text/javascript">
function confirm_alert(node) {
    return confirm("Please click on OK to continue.");
}
</script>
<a href="http://www.google.com" onclick="return confirm_alert(this);">Click Me</a>

Determine which element the mouse pointer is on top of in JavaScript

Let me start out by saying that I don't recommend using the method I'm about to suggest. It's much better to use event driven development and bind events only to the elements you're interested in knowing whether or not the mouse is over with mouseover, mouseout, mouseenter, mouseleave, etc.

If you absolutely must have the ability to know which element the mouse is over, you'd need to write a function that binds the mouseover event to everything in the DOM, and then store whatever the current element is in some variable.

You could so something like this:

window.which_element_is_the_mouse_on = (function() {

    var currentElement;

    $("body *").on('mouseover', function(e) {
        if(e.target === e.currentTarget) {
            currentElement = this;
        }
    });

    return function() {
        console.log(currentElement);
    }
}());

Basically, I've created an immediate function which sets the event on all elements and stores the current element within the closure to minimize your footprint.

Here's a working demo that calls window.which_element_is_the_mouse_on every second and logs what element the mouse is currently over to the console.

http://jsfiddle.net/LWFpJ/1/

"Cannot send session cache limiter - headers already sent"

"Headers already sent" means that your PHP script already sent the HTTP headers, and as such it can't make modifications to them now.

Check that you don't send ANY content before calling session_start. Better yet, just make session_start the first thing you do in your PHP file (so put it at the absolute beginning, before all HTML etc).

Easiest way to detect Internet connection on iOS?

Alamofire

If you are already using Alamofire for all the RESTful Api, here is what you can benifit from that.

You can add following class to your app, and call MNNetworkUtils.main.isConnected() to get a boolean on whether its connected or not.

#import Alamofire

class MNNetworkUtils {
  static let main = MNNetworkUtils()
  init() {
    manager = NetworkReachabilityManager(host: "google.com")
    listenForReachability()
  }

  private let manager: NetworkReachabilityManager?
  private var reachable: Bool = false
  private func listenForReachability() {
    self.manager?.listener = { [unowned self] status in
      switch status {
      case .notReachable:
        self.reachable = false
      case .reachable(_), .unknown:
        self.reachable = true
      }
    }
    self.manager?.startListening()
  }

  func isConnected() -> Bool {
    return reachable
  }
}

This is a singleton class. Every time, when user connect or disconnect the network, it will override self.reachable to true/false correctly, because we start listening for the NetworkReachabilityManager on singleton initialization.

Also in order to monitor reachability, you need to provide a host, currently I am using google.com feel free to change to any other hosts or one of yours if needed.

Is it possible to assign numeric value to an enum in Java?

Assuming that EXIT_CODE is referring to System . exit ( exit_code ) then you could do

enum ExitCode
{
      NORMAL_SHUTDOWN ( 0 ) , EMERGENCY_SHUTDOWN ( 10 ) , OUT_OF_MEMORY ( 20 ) , WHATEVER ( 30 ) ;

      private int value ;

      ExitCode ( int value )
      {
           this . value = value ;
      }

      public void exit ( )
      {
            System . exit ( value ) ;
      }
}

Then you can put the following at appropriate spots in your code

ExitCode . NORMAL_SHUTDOWN . exit ( ) '

possibly undefined macro: AC_MSG_ERROR

Are you setting up a local 'm4' directory? e.g.,

> aclocal -I m4 --install

Some packages come with an autogen.sh or initgen.sh shell script to run glibtoolize, autoheader, autoconf, automake. Here's an autogen.sh script I use:

#! /bin/sh

case `uname` in Darwin*) glibtoolize --copy ;;
  *) libtoolize --copy ;; esac

autoheader
aclocal -I m4 --install
autoconf

automake --foreign --add-missing --force-missing --copy

EDIT

You may need to add ACLOCAL_AMFLAGS = -I m4 to the top-level Makefile.am.

Showing an image from an array of images - Javascript

Here's a somewhat cleaner way of implementing this. This makes the following changes:

  1. The code is DRYed up a bit to remove redundant and repeated code and strings.
  2. The code is made more generic/reusable.
  3. We make the cache into an object so it has a self-contained interface and there are fewer globals.
  4. We compare .src attributes instead of DOM elements to make it work properly.

Code:

function imageCache(base, firstNum, lastNum) {
    this.cache = [];
    var img;
    for (var i = firstNum; i <= lastnum; i++) {
        img = new Image();
        img.src = base + i + ".jpg";
        this.cache.push(img);
    }
}

imageCache.prototype.nextImage(id) {
    var element = document.getElementById(id);
    var targetSrc = element.src;
    var cache = this.cache;
    for (var i = 0; i < cache.length; i++) {
        if (cache[i].src) === targetSrc) {
            i++;
            if (i >= cache.length) {
                i = 0;
            }
            element.src = cache[i].src;
            return;
        }
    }
}

// sample usage

var myCache = new imageCache('images/img/Splash_image', 1, 6);
myCache.nextImage("foo");

Some advantages of this more object oriented and DRYed approach:

  1. You can add more images by just creating the images in the numeric sequences and changing one numeric value in the constructor rather than copying lots more lines of array declarations.
  2. You can use this more than one place in your app by just creating more than one imageCache object.
  3. You can change the base URL by changing one string rather than N strings.
  4. The code size is smaller (because of the removal of repeated code).
  5. The cache object could easily be extended to offer more capabilities such as first, last, skip, etc...
  6. You could add centralize error handling in one place so if one image doesn't exist and doesn't load successfully, it's automatically removed from the cache.
  7. You can reuse this in other web pages you develop by only change the arguments to the constructor and not actually changing the implementation code.

P.S. If you don't know what DRY stands for, it's "Don't Repeat Yourself" and basically means that you should never have many copies of similar looking code. Anytime you have that, it should be reduced somehow to a loop or function or something that removes the need for lots of similarly looking copies of code. The end result will be smaller, usually easier to maintain and often more reusable.

Inheriting from a template class in c++

class Rectangle : public Area<int> {
};

change cursor to finger pointer

Solution via pure CSS as mentioned in answer marked as the best is not suitable for this situation.

The example in this topic does not have normal static href attribute, it is calling of JS only, so it will not do anything without JS.

So it is good to switch on pointer with JS only. So, solution

onMouseOver="this.style.cursor='pointer'"

as mentioned above (but I can not comment there) is the best one in this case. (But yes, generaly, for normal links not demanding JS, it is better to work with pure CSS without JS.)

Can I get div's background-image url?

I have slightly improved answer, which handles extended CSS definitions like:

background-image: url(http://d36xtkk24g8jdx.cloudfront.net/bluebar/359de8f/images/shared/noise-1.png), -webkit-linear-gradient(top, rgb(81, 127, 164), rgb(48, 96, 136))

JavaScript code:

var bg = $("div").css("background-image")
bg = bg.replace(/.*\s?url\([\'\"]?/, '').replace(/[\'\"]?\).*/, '')

Result:

"http://d36xtkk24g8jdx.cloudfront.net/bluebar/359de8f/images/shared/noise-1.png"

Highcharts - how to have a chart with dynamic height?

I had the same problem and I fixed it with:

<div id="container" style="width: 100%; height: 100%; position:absolute"></div>

The chart fits perfect to the browser even if I resize it. You can change the percentage according to your needs.

Replace first occurrence of pattern in a string

I think you can use the overload of Regex.Replace to specify the maximum number of times to replace...

var regex = new Regex(Regex.Escape("o"));
var newText = regex.Replace("Hello World", "Foo", 1);

How do I set the default locale in the JVM?

You can enforce VM arguments for a JAR file with the following code:

import java.io.File;
import java.lang.management.ManagementFactory;
import java.lang.management.RuntimeMXBean;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;

public class JVMArgumentEnforcer
{
    private String argument;

    public JVMArgumentEnforcer(String argument)
    {
        this.argument = argument;
    }

    public static long getTotalPhysicalMemory()
    {
        com.sun.management.OperatingSystemMXBean bean =
                (com.sun.management.OperatingSystemMXBean)
                        java.lang.management.ManagementFactory.getOperatingSystemMXBean();
        return bean.getTotalPhysicalMemorySize();
    }

    public static boolean isUsing64BitJavaInstallation()
    {
        String bitVersion = System.getProperty("sun.arch.data.model");

        return bitVersion.equals("64");
    }

    private boolean hasTargetArgument()
    {
        RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean();
        List<String> inputArguments = runtimeMXBean.getInputArguments();

        return inputArguments.contains(argument);
    }

    public void forceArgument() throws Exception
    {
        if (!hasTargetArgument())
        {
            // This won't work from IDEs
            if (JARUtilities.isRunningFromJARFile())
            {
                // Supply the desired argument
                restartApplication();
            } else
            {
                throw new IllegalStateException("Please supply the VM argument with your IDE: " + argument);
            }
        }
    }

    private void restartApplication() throws Exception
    {
        String javaBinary = getJavaBinaryPath();
        ArrayList<String> command = new ArrayList<>();
        command.add(javaBinary);
        command.add("-jar");
        command.add(argument);
        String currentJARFilePath = JARUtilities.getCurrentJARFilePath();
        command.add(currentJARFilePath);

        ProcessBuilder processBuilder = new ProcessBuilder(command);
        processBuilder.start();

        // Kill the current process
        System.exit(0);
    }

    private String getJavaBinaryPath()
    {
        return System.getProperty("java.home")
                + File.separator + "bin"
                + File.separator + "java";
    }

    public static class JARUtilities
    {
        static boolean isRunningFromJARFile() throws URISyntaxException
        {
            File currentJarFile = getCurrentJARFile();

            return currentJarFile.getName().endsWith(".jar");
        }

        static String getCurrentJARFilePath() throws URISyntaxException
        {
            File currentJarFile = getCurrentJARFile();

            return currentJarFile.getPath();
        }

        private static File getCurrentJARFile() throws URISyntaxException
        {
            return new File(JVMArgumentEnforcer.class.getProtectionDomain().getCodeSource().getLocation().toURI());
        }
    }
}

It is used as follows:

JVMArgumentEnforcer jvmArgumentEnforcer = new JVMArgumentEnforcer("-Duser.language=pt-BR"); // For example
jvmArgumentEnforcer.forceArgument();

Number input type that takes only integers?

Set the step attribute to 1:

<input type="number" step="1" />

This seems a bit buggy in Chrome right now so it might not be the best solution at the moment.

A better solution is to use the pattern attribute, that uses a regular expression to match the input:

<input type="text" pattern="\d*" />

\d is the regular expression for a number, * means that it accepts more than one of them. Here is the demo: http://jsfiddle.net/b8NrE/1/

Getting value of HTML text input

If your page is refreshed on submitting - yes, but only through the querystring: http://www.bloggingdeveloper.com/post/JavaScript-QueryString-ParseGet-QueryString-with-Client-Side-JavaScript.aspx (You must use method "GET" then). Else, you can return its value from the php script.

How to clear mysql screen console in windows?

I had the same issue, and CTRL+L worked for me on Windows 10.

Python multiprocessing PicklingError: Can't pickle <type 'function'>

When this problem comes up with multiprocessing a simple solution is to switch from Pool to ThreadPool. This can be done with no change of code other than the import-

from multiprocessing.pool import ThreadPool as Pool

This works because ThreadPool shares memory with the main thread, rather than creating a new process- this means that pickling is not required.

The downside to this method is that python isn't the greatest language with handling threads- it uses something called the Global Interpreter Lock to stay thread safe, which can slow down some use cases here. However, if you're primarily interacting with other systems (running HTTP commands, talking with a database, writing to filesystems) then your code is likely not bound by CPU and won't take much of a hit. In fact I've found when writing HTTP/HTTPS benchmarks that the threaded model used here has less overhead and delays, as the overhead from creating new processes is much higher than the overhead for creating new threads.

So if you're processing a ton of stuff in python userspace this might not be the best method.

Find OpenCV Version Installed on Ubuntu

There is also a flag CV_VERSION which will print out the full version of opencv

PHP mail not working for some reason

The mail function do not guarantee the actual delivery of mail. All it do is to pass the message to external program (usually sendmail). You need a properly configured SMTP server in order for this to work. Also keep in mind it does not support SMTP authentication. You may check out the PEAR::Mail library of SwiftMailer, both of them give you more options.

Declaring variables inside or outside of a loop

You have a risk of NullPointerException if your calculateStr() method returns null and then you try to call a method on str.

More generally, avoid having variables with a null value. It stronger for class attributes, by the way.

Check if an HTML input element is empty or has no value entered by user

getElementById will return false if the element was not found in the DOM.

var el = document.getElementById("customx");
if (el !== null && el.value === "")
{
  //The element was found and the value is empty.
}

Checking whether a string starts with XXXX

RanRag has already answered it for your specific question.

However, more generally, what you are doing with

if [[ "$string" =~ ^hello ]]

is a regex match. To do the same in Python, you would do:

import re
if re.match(r'^hello', somestring):
    # do stuff

Obviously, in this case, somestring.startswith('hello') is better.

How to use LocalBroadcastManager?

When you'll play enough with LocalBroadcastReceiver I'll suggest you to give Green Robot's EventBus a try - you will definitely realize the difference and usefulness of it compared to LBR. Less code, customizable about receiver's thread (UI/Bg), checking receivers availability, sticky events, events could be used as data delivery etc.

How to efficiently check if variable is Array or Object (in NodeJS & V8)?

The Best Way I Can Use My Project.Use hasOwnProperty in Tricky Way!.

var arr = []; (or) arr = new Array();
var obj = {}; (or) arr = new Object();

arr.constructor.prototype.hasOwnProperty('push') //true (This is an Array)

obj.constructor.prototype.hasOwnProperty('push') // false (This is an Object)

Changing Java Date one hour back

This can be achieved using java.util.Date. The following code will subtract 1 hour from your date.

Date date = new Date(yourdate in date format);
Date newDate = DateUtils.addHours(date, -1)

Similarly for subtracting 20 seconds from your date

newDate = DateUtils.addSeconds(date, -20)    

How do I find a list of Homebrew's installable packages?

brew help will show you the list of commands that are available.

brew list will show you the list of installed packages. You can also append formulae, for example brew list postgres will tell you of files installed by postgres (providing it is indeed installed).

brew search <search term> will list the possible packages that you can install. brew search post will return multiple packages that are available to install that have post in their name.

brew info <package name> will display some basic information about the package in question.

You can also search http://searchbrew.com or https://brewformulas.org (both sites do basically the same thing)

Error: expected type-specifier before 'ClassName'

First of all, let's try to make your code a little simpler:

// No need to create a circle unless it is clearly necessary to
// demonstrate the problem

// Your Rect2f defines a default constructor, so let's use it for simplicity.
shared_ptr<Shape> rect(new Rect2f());

Okay, so now we see that the parentheses are clearly balanced. What else could it be? Let's check the following code snippet's error:

int main() {
    delete new T();
}

This may seem like weird usage, and it is, but I really hate memory leaks. However, the output does seem useful:

In function 'int main()':
Line 2: error: expected type-specifier before 'T'

Aha! Now we're just left with the error about the parentheses. I can't find what causes that; however, I think you are forgetting to include the file that defines Rect2f.

What are the undocumented features and limitations of the Windows FINDSTR command?

findstr sometimes hangs unexpectedly when searching large files.

I haven't confirmed the exact conditions or boundary sizes. I suspect any file larger 2GB may be at risk.

I have had mixed experiences with this, so it is more than just file size. This looks like it may be a variation on FINDSTR hangs on XP and Windows 7 if redirected input does not end with LF, but as demonstrated this particular problem manifests when input is not redirected.

The following command line session (Windows 7) demonstrates how findstr can hang when searching a 3GB file.

C:\Data\Temp\2014-04>echo 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890> T100B.txt

C:\Data\Temp\2014-04>for /L %i in (1,1,10) do @type T100B.txt >> T1KB.txt

C:\Data\Temp\2014-04>for /L %i in (1,1,1000) do @type T1KB.txt >> T1MB.txt

C:\Data\Temp\2014-04>for /L %i in (1,1,1000) do @type T1MB.txt >> T1GB.txt

C:\Data\Temp\2014-04>echo find this line>> T1GB.txt

C:\Data\Temp\2014-04>copy T1GB.txt + T1GB.txt + T1GB.txt T3GB.txt
T1GB.txt
T1GB.txt
T1GB.txt
        1 file(s) copied.

C:\Data\Temp\2014-04>dir
 Volume in drive C has no label.
 Volume Serial Number is D2B2-FFDF

 Directory of C:\Data\Temp\2014-04

2014/04/08  04:28 PM    <DIR>          .
2014/04/08  04:28 PM    <DIR>          ..
2014/04/08  04:22 PM               102 T100B.txt
2014/04/08  04:28 PM     1 020 000 016 T1GB.txt
2014/04/08  04:23 PM             1 020 T1KB.txt
2014/04/08  04:23 PM         1 020 000 T1MB.txt
2014/04/08  04:29 PM     3 060 000 049 T3GB.txt
               5 File(s)  4 081 021 187 bytes
               2 Dir(s)  51 881 050 112 bytes free
C:\Data\Temp\2014-04>rem Findstr on the 1GB file does not hang

C:\Data\Temp\2014-04>findstr "this" T1GB.txt
find this line

C:\Data\Temp\2014-04>rem On the 3GB file, findstr hangs and must be aborted... even though it clearly reaches end of file

C:\Data\Temp\2014-04>findstr "this" T3GB.txt
find this line
find this line
find this line
^C
C:\Data\Temp\2014-04>

Note, I've verified in a hex editor that all lines are terminated with CRLF. The only anomaly is that the file is terminated with 0x1A due to the way copy works. Note however, that this anomaly doesn't cause a problem on "small" files.

With additional testing I have confirmed the following:

  • Using copy with the /b option for binary files prevents the addition of the 0x1A character, and findstr doesn't hang on the 3GB file.
  • Terminating the 3GB file with a different character also causes a findstr to hang.
  • The 0x1A character doesn't cause any problems on a "small" file. (Similarly for other terminating characters.)
  • Adding CRLF after 0x1A resolves the problem. (LF by itself would probably suffice.)
  • Using type to pipe the file into findstr works without hanging. (This might be due to a side effect of either type or | that inserts an additional End Of Line.)
  • Use redirected input < also causes findstr to hang. But this is expected; as explained in dbenham's post: "redirected input must end in LF".

ASP.NET document.getElementById('<%=Control.ClientID%>'); returns null

Gotcha!

You have to use RegisterStartupScript instead of RegisterClientScriptBlock

Here My Example.

MasterPage:

<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="MasterPage.master.cs"
    Inherits="prueba.MasterPage" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>

    <script type="text/javascript">

        function confirmCallBack() {
            var a = document.getElementById('<%= Page.Master.FindControl("ContentPlaceHolder1").FindControl("Button1").ClientID %>');

            alert(a.value);

        }

    </script>

    <asp:ContentPlaceHolder ID="head" runat="server">
    </asp:ContentPlaceHolder>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
        </asp:ContentPlaceHolder>
    </div>
    </form>
</body>
</html>

WebForm1.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.Master" AutoEventWireup="true"
    CodeBehind="WebForm1.aspx.cs" Inherits="prueba.WebForm1" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">

</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:Button ID="Button1" runat="server" Text="Button" />
</asp:Content>

WebForm1.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace prueba
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            ClientScript.RegisterStartupScript(this.GetType(), "js", "confirmCallBack();", true);

        }
    }
}

How to Round to the nearest whole number in C#

Math.Ceiling

always rounds up (towards the ceiling)

Math.Floor

always rounds down (towards to floor)

what you are after is simply

Math.Round

which rounds as per this post

glm rotate usage in Opengl

I noticed that you can also get errors if you don't specify the angles correctly, even when using glm::rotate(Model, angle_in_degrees, glm::vec3(x, y, z)) you still might run into problems. The fix I found for this was specifying the type as glm::rotate(Model, (glm::mediump_float)90, glm::vec3(x, y, z)) instead of just saying glm::rotate(Model, 90, glm::vec3(x, y, z))

Or just write the second argument, the angle in radians (previously in degrees), as a float with no cast needed such as in:

glm::mat4 rotationMatrix = glm::rotate(glm::mat4(1.0f), 3.14f, glm::vec3(1.0));

You can add glm::radians() if you want to keep using degrees. And add the includes:

#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"

Change primary key column in SQL Server

Necromancing.
It looks you have just as good a schema to work with as me... Here is how to do it correctly:

In this example, the table name is dbo.T_SYS_Language_Forms, and the column name is LANG_UID

-- First, chech if the table exists...
IF 0 < (
    SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES 
    WHERE TABLE_TYPE = 'BASE TABLE'
    AND TABLE_SCHEMA = 'dbo'
    AND TABLE_NAME = 'T_SYS_Language_Forms'
)
BEGIN
    -- Check for NULL values in the primary-key column
    IF 0 = (SELECT COUNT(*) FROM T_SYS_Language_Forms WHERE LANG_UID IS NULL)
    BEGIN
        ALTER TABLE T_SYS_Language_Forms ALTER COLUMN LANG_UID uniqueidentifier NOT NULL 

        -- No, don't drop, FK references might already exist...
        -- Drop PK if exists 
        -- ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT pk_constraint_name 
        --DECLARE @pkDropCommand nvarchar(1000) 
        --SET @pkDropCommand = N'ALTER TABLE T_SYS_Language_Forms DROP CONSTRAINT ' + QUOTENAME((SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
        --WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' 
        --AND TABLE_SCHEMA = 'dbo' 
        --AND TABLE_NAME = 'T_SYS_Language_Forms' 
        ----AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms' 
        --))
        ---- PRINT @pkDropCommand 
        --EXECUTE(@pkDropCommand) 

        -- Instead do
        -- EXEC sp_rename 'dbo.T_SYS_Language_Forms.PK_T_SYS_Language_Forms1234565', 'PK_T_SYS_Language_Forms';


        -- Check if they keys are unique (it is very possible they might not be) 
        IF 1 >= (SELECT TOP 1 COUNT(*) AS cnt FROM T_SYS_Language_Forms GROUP BY LANG_UID ORDER BY cnt DESC)
        BEGIN

            -- If no Primary key for this table
            IF 0 =  
            (
                SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
                WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' 
                AND TABLE_SCHEMA = 'dbo' 
                AND TABLE_NAME = 'T_SYS_Language_Forms' 
                -- AND CONSTRAINT_NAME = 'PK_T_SYS_Language_Forms' 
            )
                ALTER TABLE T_SYS_Language_Forms ADD CONSTRAINT PK_T_SYS_Language_Forms PRIMARY KEY CLUSTERED (LANG_UID ASC)
            ;

            -- Adding foreign key
            IF 0 = (SELECT COUNT(*) FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS WHERE CONSTRAINT_NAME = 'FK_T_ZO_SYS_Language_Forms_T_SYS_Language_Forms') 
                ALTER TABLE T_ZO_SYS_Language_Forms WITH NOCHECK ADD CONSTRAINT FK_T_ZO_SYS_Language_Forms_T_SYS_Language_Forms FOREIGN KEY(ZOLANG_LANG_UID) REFERENCES T_SYS_Language_Forms(LANG_UID); 
        END -- End uniqueness check
        ELSE
            PRINT 'FSCK, this column has duplicate keys, and can thus not be changed to primary key...' 
    END -- End NULL check
    ELSE
        PRINT 'FSCK, need to figure out how to update NULL value(s)...' 
END 

What does the fpermissive flag do?

A common case for simply setting -fpermissive and not sweating it exists: the thoroughly-tested and working third-party library that won't compile on newer compiler versions without -fpermissive. These libraries exist, and are very likely not the application developer's problem to solve, nor in the developer's schedule budget to do it.

Set -fpermissive and move on in that case.

MySQL table is marked as crashed and last (automatic?) repair failed

Try running the following query:

repair table <table_name>;

I had the same issue and it solved me the problem.

How to get 30 days prior to current date?

This is an ES6 version

let date = new Date()
let newDate = new Date(date.setDate(date.getDate()-30))
console.log(newDate.getMonth()+1 + '/' + newDate.getDate() + '/' + newDate.getFullYear() )

How to increase buffer size in Oracle SQL Developer to view all records?

If you are running a script, instead of a statement, you can increase this by selecting Tools/Preferences/Worksheet and increasing "Max Rows to print in a script". The default is 5000, you can change it to any size.

Best way to pretty print a hash

If you don't have any fancy gem action, but do have JSON, this CLI line will work on a hash:

puts JSON.pretty_generate(my_hash).gsub(":", " =>")

#=>
{
  :key1 => "value1",

  :key2 => "value2",

  :key3 => "value3"
}

Raising a number to a power in Java

Your calculation is likely the culprit. Try using:

bmi = weight / Math.pow(height / 100.0, 2.0);

Because both height and 100 are integers, you were likely getting the wrong answer when dividing. However, 100.0 is a double. I suggest you make weight a double as well. Also, the ^ operator is not for powers. Use the Math.pow() method instead.

Prevent div from moving while resizing the page

I'd rather use static widths and if you'd like your page to resize depending on screen size, you can have a look at media queries.

Or, you can set a min-width on elements like header, navigation, content etc.

How to set cache: false in jQuery.get call

To me, the correct way of doing it would be the ones listed. Either ajax or ajaxSetup. If you really want to use get and not use ajaxSetup then you could create your own parameter and give it the value of the the current date/time.

I would however question your motives in not using one of the other methods.