Programs & Examples On #Malware

Malware is any malicious software, script, or code developed or used for the purpose of compromising or harming information assets without the owner’s informed consent. Examples include viruses, worms, spyware, keyloggers, backdoors, etc.

Visual Studio 2015 installer hangs during install?

The current version of AVG Free antivirus is incompatible with Microsoft Visual Studio 2015.

  1. It does not allow Visual Studio to be installed on the computer. It gets stuck at "Creating restore point". Visual Studio installs perfectly when AVG is turned off.

  2. Any code compiled in "Release" mode targeting x86 platform/environment (in project properties) does not compile. It compiles successfully when AVG is turned off.

I posted the issues in AVG support forum but no one responded.

Where can I download mysql jdbc jar from?

If you have WL server installed, pick it up from under

Otherwise, download it from:

Get all files modified in last 30 days in a directory

A couple of issues

  • You're not limiting it to files, so when it finds a matching directory it will list every file within it.
  • You can't use > in -exec without something like bash -c '... > ...'. Though the > will overwrite the file, so you want to redirect the entire find anyway rather than each -exec.
  • +30 is older than 30 days, -30 would be modified in last 30 days.
  • -exec really isn't needed, you could list everything with various -printf options.

Something like below should work

find . -type f -mtime -30 -exec ls -l {} \; > last30days.txt

Example with -printf

find . -type f -mtime -30 -printf "%M %u %g %TR %TD %p\n" > last30days.txt

This will list files in format "permissions owner group time date filename". -printf is generally preferable to -exec in cases where you don't have to do anything complicated. This is because it will run faster as a result of not having to execute subshells for each -exec. Depending on the version of find, you may also be able to use -ls, which has a similar format to above.

How to display the first few characters of a string in Python?

You can 'slice' a string very easily, just like you'd pull items from a list:

a_string = 'This is a string'

To get the first 4 letters:

first_four_letters = a_string[:4]
>>> 'This'

Or the last 5:

last_five_letters = a_string[-5:]
>>> 'string'

So applying that logic to your problem:

the_string = '416d76b8811b0ddae2fdad8f4721ddbe|d4f656ee006e248f2f3a8a93a8aec5868788b927|12a5f648928f8e0b5376d2cc07de8e4cbf9f7ccbadb97d898373f85f0a75c47f '
first_32_chars = the_string[:32]
>>> 416d76b8811b0ddae2fdad8f4721ddbe

Failed to fetch URL, reason: Connection to refused

If you are on Windows 7, simply run Eclipse with Admin privilege will solve this issue.

Just tried this on my Windows 7 64bits OS.

Is it possible to "decompile" a Windows .exe? Or at least view the Assembly?

You may get some information viewing it in assembly, but I think the easiest thing to do is fire up a virtual machine and see what it does. Make sure you have no open shares or anything like that that it can jump through though ;)

What are valid values for the id attribute in HTML?

You can technically use colons and periods in id/name attributes, but I would strongly suggest avoiding both.

In CSS (and several JavaScript libraries like jQuery), both the period and the colon have special meaning and you will run into problems if you're not careful. Periods are class selectors and colons are pseudo-selectors (eg., ":hover" for an element when the mouse is over it).

If you give an element the id "", your CSS selector will look like this: { ... /* some rules */ ... }

Which is really saying, "the element with an id of 'my', a class of 'cool' and the 'thing' pseudo-selector" in CSS-speak.

Stick to A-Z of any case, numbers, underscores and hyphens. And as said above, make sure your ids are unique.

That should be your first concern.

How many files can I put in a directory?

Keep in mind that on Linux if you have a directory with too many files, the shell may not be able to expand wildcards. I have this issue with a photo album hosted on Linux. It stores all the resized images in a single directory. While the file system can handle many files, the shell can't. Example:

-shell-3.00$ ls A*
-shell: /bin/ls: Argument list too long


-shell-3.00$ chmod 644 *jpg
-shell: /bin/chmod: Argument list too long

Where does application data file actually stored on android device?

Application Private Data files are stored within <internal_storage>/data/data/<package>

Files being stored in the internal storage can be accessed with openFileOutput() and openFileInput()

When those files are created as MODE_PRIVATE it is not possible to see/access them within another application such as a FileManager.

Convert Little Endian to Big Endian

I think you can use function htonl(). Network byte order is big endian.

Change fill color on vector asset in Android Studio

You can do it.

BUT you cannot use @color references for colors (..lame), otherwise it will work only for L+

<vector xmlns:android=""
    android:pathData="M15.5,14h-0.79l-0.28,-0.27C15.41,12.59 16,11.11 16,9.5 16,5.91 13.09,3 9.5,3S3,5.91 3,9.5 5.91,16 9.5,16c1.61,0 3.09,-0.59 4.23,-1.57l0.27,0.28v0.79l5,4.99L20.49,19l-4.99,-5zm-6,0C7.01,14 5,11.99 5,9.5S7.01,5 9.5,5 14,7.01 14,9.5 11.99,14 9.5,14z"/>

font awesome icon in select option

You can simply add a FontAwesome icon to your select dropdown as text. You only need a few things in CSS only, the FontAwesome CSS and the unicode. For example &#xf26e;:

select {_x000D_
  font-family: 'FontAwesome', 'Second Font name'_x000D_
<link href="" rel="stylesheet"/>_x000D_
  <option>Hi, &#xf042;</option>_x000D_
  <option>Hi, &#xf043;</option>_x000D_
  <option>Hi, &#xf044;</option>_x000D_
  <option>Hi, &#xf045;</option>_x000D_
  <option>Hi, &#xf046;</option>_x000D_

Working fiddle

The unicodes can be found when you click on an icon: Fontawesome

According to the comment below and issue on Github, the unicode in select elements won't work on OSX (yet).

Update: from the Github issue, adding multiple attribute to select element makes it work on:

OSX El Capitan 10.11.4

  • Chrome version 50.0.2661.75 (64-bit)
  • Sarafi version 9.1
  • Firefox version 45.0.2

  font-family: FontAwesome, sans-serif;_x000D_
<link href="" rel="stylesheet"/>_x000D_
<select multiple>_x000D_
  <option>&#xf26e 500px</option>_x000D_
  <option>&#xf042 Adjust</option>_x000D_
  <option>&#xf170 Adn</option>_x000D_
  <option>&#xf037 Align-center</option>_x000D_
  <option>&#xf039 Align-justify</option>_x000D_
  <option>&#xf036 Align-left</option>_x000D_
  <option>&#xf038 Align-right</option>_x000D_


oracle sql: update if exists else insert

MERGE doesn't need "multiple tables", but it does need a query as the source. Something like this should work:

MERGE INTO mytable d
USING (SELECT 1 id, 'x' name from dual) s
ON ( =

Alternatively you can do this in PL/SQL:

  INSERT INTO mytable (id, name) VALUES (1, 'x');
    UPDATE mytable
    SET    name = 'x'
    WHERE id = 1;

I cannot start SQL Server browser

right click on SQL Server browser and properties, then Connection tab and chose open session with system account and not this account. then apply and chose automatic and finally run the server.

Microsoft Advertising SDK doesn't deliverer ads

I only use MicrosoftAdvertising.Mobile and Microsoft.Advertising.Mobile.UI and I am served ads. The SDK should only add the DLLs not reference itself.

Note: You need to explicitly set width and height Make sure the phone dialer, and web browser capabilities are enabled

Followup note: Make sure that after you've removed the SDK DLL, that the xmlns references are not still pointing to it. The best route to take here is

  1. Remove the XAML for the ad
  2. Remove the xmlns declaration (usually at the top of the page, but sometimes will be declared in the ad itself)
  3. Remove the bad DLL (the one ending in .SDK )
  4. Do a Clean and then Build (clean out anything remaining from the DLL)
  5. Add the xmlns reference (actual reference is below)
  6. Add the ad to the page (example below)

Here is the xmlns reference:


Then the ad itself:

<AdNamespace:AdControl x:Name="myAd" Height="80" Width="480"                    AdUnitId="yourAdUnitIdHere" ApplicationId="yourIdHere"/> 

Is if(document.getElementById('something')!=null) identical to if(document.getElementById('something'))?

It's better (but wordier) to use:

var element = document.getElementById('something');
if (element != null && element.value == '') {

Please note, the first version of my answer was wrong:

var element = document.getElementById('something');
if (typeof element !== "undefined" && element.value == '') {

because getElementById() always return an object (null object if not found) and checking for"undefined" would never return a false, as typeof null !== "undefined" is still true.

how to customize `show processlist` in mysql?

You can just capture the output and pass it through a filter, something like:

mysql show processlist
    | grep -v '^\+\-\-'
    | grep -v '^| Id'
    | sort -n -k12

The two greps strip out the header and trailer lines (others may be needed if there are other lines not containing useful information) and the sort is done based on the numeric field number 12 (I think that's right).

This one works for your immediate output:

mysql show processlist
    | grep -v '^\+\-\-'
    | grep -v '^| Id'
    | grep -v  '^[0-9][0-9]* rows in set '
    | grep -v '^ '
    | sort -n -k12

Background color not showing in print preview

You can also use the box-shadow property.

Cancel a UIView animation?

To pause an animation without reverting state to original or final:

CFTimeInterval paused_time = [myView.layer convertTime:CACurrentMediaTime() fromLayer:nil];
myView.layer.speed = 0.0;
myView.layer.timeOffset = paused_time;

MySQL check if a table exists without throwing an exception

Zend framework

public function verifyTablesExists($tablesName)
        $db = $this->getDefaultAdapter();
        $config_db = $db->getConfig();

        $sql = "SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = '{$config_db['dbname']}'  AND table_name = '{$tablesName}'";

        $result = $db->fetchRow($sql);
        return $result;


How to jump to a particular line in a huge text file?

Do the lines themselves contain any index information? If the content of each line was something like "<line index>:Data", then the seek() approach could be used to do a binary search through the file, even if the amount of Data is variable. You'd seek to the midpoint of the file, read a line, check whether its index is higher or lower than the one you want, etc.

Otherwise, the best you can do is just readlines(). If you don't want to read all 15MB, you can use the sizehint argument to at least replace a lot of readline()s with a smaller number of calls to readlines().

C: convert double to float, preserving decimal point precision

float and double don't store decimal places. They store binary places: float is (assuming IEEE 754) 24 significant bits (7.22 decimal digits) and double is 53 significant bits (15.95 significant digits).

Converting from double to float will give you the closest possible float, so rounding won't help you. Goining the other way may give you "noise" digits in the decimal representation.

#include <stdio.h>

int main(void) {
    double orig = 12345.67;
    float f = (float) orig;
    printf("%.17g\n", f); // prints 12345.669921875
    return 0;

To get a double approximation to the nice decimal value you intended, you can write something like:

double round_to_decimal(float f) {
    char buf[42];
    sprintf(buf, "%.7g", f); // round to 7 decimal digits
    return atof(buf);

How to use Jackson to deserialise an array of objects

For Generic Implementation:

public static <T> List<T> parseJsonArray(String json,
                                         Class<T> classOnWhichArrayIsDefined) 
                                         throws IOException, ClassNotFoundException {
   ObjectMapper mapper = new ObjectMapper();
   Class<T[]> arrayClass = (Class<T[]>) Class.forName("[L" + classOnWhichArrayIsDefined.getName() + ";");
   T[] objects = mapper.readValue(json, arrayClass);
   return Arrays.asList(objects);

Read file data without saving it in Flask

I was trying to do the exact same thing, open a text file (a CSV for Pandas actually). Don't want to make a copy of it, just want to open it. The form-WTF has a nice file browser, but then it opens the file and makes a temporary file, which it presents as a memory stream. With a little work under the hood,

form = UploadForm() 
 if form.validate_on_submit(): 
      filename = secure_filename(  
      filestream =
      ef = pd.read_csv( filestream  )
      sr = pd.DataFrame(ef)  
      return render_template('dataframe.html',tables=[sr.to_html(justify='center, classes='table table-bordered table-hover')],titles = [filename], form=form) 

How to export specific request to file using postman?

  1. Click on the "Code" button upright of the request page.
  2. From the opened window select cURL.
  3. Copy and share the generated code.

enter image description here

You can use this curl request to import it into Postman.

#1292 - Incorrect date value: '0000-00-00'

After reviewing MySQL 5.7 changes, MySql stopped supporting zero values in date / datetime.

It's incorrect to use zeros in date or in datetime, just put null instead of zeros.

DB2 Query to retrieve all table names for a given schema

You can also get the table names simply by typing LIST TABLES in DB2

vba: get unique values from array

No, nothing built-in. Do it yourself:

  • Instantiate a Scripting.Dictionary object
  • Write a For loop over your array (be sure to use LBound() and UBound() instead of looping from 0 to x!)
  • On each iteration, check Exists() on the dictionary. Add every array value (that doesn't already exist) as a key to the dictionary (use CStr() since keys must be strings as I've just learned, keys can be of any type in a Scripting.Dictionary), also store the array value itself into the dictionary.
  • When done, use Keys() (or Items()) to return all values of the dictionary as a new, now unique array.
  • In my tests, the Dictionary keeps original order of all added values, so the output will be ordered like the input was. I'm not sure if this is documented and reliable behavior, though.

How to pass an array within a query string?

Here's what I figured out:

Submitting multi-value form fields, i.e. submitting arrays through GET/POST vars, can be done several different ways, as a standard is not necessarily spelled out.

Three possible ways to send multi-value fields or arrays would be:

  • ?cars[]=Saab&cars[]=Audi (Best way- PHP reads this into an array)
  • ?cars=Saab&cars=Audi (Bad way- PHP will only register last value)
  • ?cars=Saab,Audi (Haven't tried this)

Form Examples

On a form, multi-valued fields could take the form of a select box set to multiple:

    <select multiple="multiple" name="cars[]"> 

(NOTE: In this case, it would be important to name the select control some_name[], so that the resulting request vars would be registered as an array by PHP)

... or as multiple hidden fields with the same name:

<input type="hidden" name="cars[]" value="Volvo">
<input type="hidden" name="cars[]" value="Saab">
<input type="hidden" name="cars[]" value="Mercedes">

NOTE: Using field[] for multiple values is really poorly documented. I don't see any mention of it in the section on multi-valued keys in Query string - Wikipedia, or in the W3C docs dealing with multi-select inputs.


As commenters have pointed out, this is very much framework-specific. Some examples:

Query string:



"list_a": "3", 
"list_c": "1,2,3"


 "list_a": [
  "list_b[]": [
  "list_c": "1,2,3"

(Angular discussion)

See comments for examples in node.js, Wordpress,

Maintaining order: One more thing to consider is that if you need to maintain the order of your items (i.e. array as an ordered list), you really only have one option, which is passing a delimited list of values, and explicitly converting it to an array yourself.

How to check if any value is NaN in a Pandas DataFrame

To find out which rows have NaNs in a specific column:

nan_rows = df[df['name column'].isnull()]

How to print SQL statement in codeigniter model

if you need a quick test on your query, this works great for me

echo $this->db->last_query(); die;

How to set delay in android?

I think the easiest and most stable and the most useful way as of 2020 is using delay function of Coroutines instead of Runnable. Coroutines is a good concept to handle asynchronous jobs and its delay component will be this answer's focus.

WARNING: Coroutines need Kotlin language and I didn't convert the codes to Kotlin but I think everybody can understand the main concept..

Just add the Coroutines on your build.gradle:

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.9'

Add a job to your class (activity, fragment or something) which you will use coroutines in it:

private var job: Job = Job()
override val coroutineContext: CoroutineContext
    get() = Dispatchers.Main + job

And you can use Coroutines anywhere on the class by using launch{ } body. So you can write your code like this:

public void onClick(View v) {

    launch {

        switch(v.getId()) {
            case R . id . rollDice :
            Random ranNum = new Random();
            int number = ranNum . nextInt (6) + 1;
            diceNum.setText("" + number);
            sum = sum + number;
            for (i= 0;i < 8;i++){
                for (j= 0;j < 8;j++){
                    int value =(Integer) buttons [i][j].getTag();
                    if (value == sum) {
                        inew = i;
                        jnew = j;



It's All...

Dont't forget that launch{} function is asynchronous and the for loop will not wait for delay function to finish if you write like this:


So, launch{ } should cover the for loop if you want all the for loop to wait for delay.

Another benefit of launch{ } is that you are making the for loop asynchronous, which means it is not gonna block the main UI thread of the application on heavy processes.

How to get the start time of a long-running Linux process?

As a follow-up to Adam Matan's answer, the /proc/<pid> directory's time stamp as such is not necessarily directly useful, but you can use

awk -v RS=')' 'END{print $20}' /proc/12345/stat

to get the start time in clock ticks since system boot.1

This is a slightly tricky unit to use; see also convert jiffies to seconds for details.

awk -v ticks="$(getconf CLK_TCK)" 'NR==1 { now=$1; next }
    END { printf "%9.0f\n", now - ($20/ticks) }' /proc/uptime RS=')' /proc/12345/stat

This should give you seconds, which you can pass to strftime() to get a (human-readable, or otherwise) timestamp.

awk -v ticks="$(getconf CLK_TCK)" 'NR==1 { now=$1; next }
    END { print strftime("%c", systime() - (now-($20/ticks))) }' /proc/uptime RS=')' /proc/12345/stat

Updated with some fixes from Stephane Chazelas in the comments; thanks as always!

If you only have Mawk, maybe try

awk -v ticks="$(getconf CLK_TCK)" -v epoch="$(date +%s)" '
  NR==1 { now=$1; next }
  END { printf "%9.0f\n", epoch - (now-($20/ticks)) }' /proc/uptime RS=')' /proc/12345/stat |
xargs -i date -d @{}

1 man proc; search for starttime.

"And" and "Or" troubles within an IF statement

This is not an answer, but too long for a comment.

In reply to JP's answers / comments, I have run the following test to compare the performance of the 2 methods. The Profiler object is a custom class - but in summary, it uses a kernel32 function which is fairly accurate (Private Declare Sub GetLocalTime Lib "kernel32" (lpSystemTime As SYSTEMTIME)).

Sub test()

  Dim origNum As String
  Dim creditOrDebit As String
  Dim b As Boolean
  Dim p As Profiler
  Dim i As Long

  Set p = New_Profiler

  origNum = "30062600006"
  creditOrDebit = "D"

  p.startTimer ("nested_ifs")

  For i = 1 To 1000000

    If creditOrDebit = "D" Then
      If origNum = "006260006" Then
        b = True
      ElseIf origNum = "30062600006" Then
        b = True
      End If
    End If

  Next i

  p.stopTimer ("nested_ifs")
  p.startTimer ("or_and")

  For i = 1 To 1000000

    If (origNum = "006260006" Or origNum = "30062600006") And creditOrDebit = "D" Then
      b = True
    End If

  Next i

  p.stopTimer ("or_and")


End Sub

The results of 5 runs (in ms for 1m loops):

20-Jun-2012 19:28:25
nested_ifs (x1): 156 - Last Run: 156 - Average Run: 156
or_and (x1): 125 - Last Run: 125 - Average Run: 125

20-Jun-2012 19:28:26
nested_ifs (x1): 156 - Last Run: 156 - Average Run: 156
or_and (x1): 125 - Last Run: 125 - Average Run: 125

20-Jun-2012 19:28:27
nested_ifs (x1): 140 - Last Run: 140 - Average Run: 140
or_and (x1): 125 - Last Run: 125 - Average Run: 125

20-Jun-2012 19:28:28
nested_ifs (x1): 140 - Last Run: 140 - Average Run: 140
or_and (x1): 141 - Last Run: 141 - Average Run: 141

20-Jun-2012 19:28:29
nested_ifs (x1): 156 - Last Run: 156 - Average Run: 156
or_and (x1): 125 - Last Run: 125 - Average Run: 125


If creditOrDebit is not "D", JP's code runs faster (around 60ms vs. 125ms for the or/and code).

How to see the proxy settings on windows?

An update to @rleelr:
It's possible to view proxy settings in Google Chrome:


Then select

View live HTTP/2 sessions

Then select one of the live sessions (you need to have some tabs open). There you find:

t=504112 [st= 0] +HTTP2_SESSION  [dt=?]
                  --> host = ""
                  --> proxy = "PROXY"

How to show an alert box in PHP?

There is a syntax error (typo):

It's alert not alery.

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

I'd suggest reading through the Firebase documentation. Specifically, see the Saving Data portion of the Firebase JavaScript Web Guide.

From the guide:

Getting the Unique ID Generated by push()

Calling push() will return a reference to the new data path, which you can use to get the value of its ID or set data to it. The following code will result in the same data as the above example, but now we'll have access to the unique push ID that was generated

// Generate a reference to a new location and add some data using push()
var newPostRef = postsRef.push({
 author: "gracehop",
 title: "Announcing COBOL, a New Programming Language"

// Get the unique ID generated by push() by accessing its key
var postID = newPostRef.key;


  • A push generates a new data path, with a server timestamp as its key. These keys look like -JiGh_31GA20JabpZBfa, so not numeric.
  • If you wanted to make a numeric only ID, you would make that a parameter of the object to avoid overwriting the generated key.
    • The keys (the paths of the new data) are guaranteed to be unique, so there's no point in overwriting them with a numeric key.
    • You can instead set the numeric ID as a child of the object.
    • You can then query objects by that ID child using Firebase Queries.

From the guide:

In JavaScript, the pattern of calling push() and then immediately calling set() is so common that we let you combine them by just passing the data to be set directly to push() as follows. Both of the following write operations will result in the same data being saved to Firebase:

// These two methods are equivalent:
  author: "gracehop",
  title: "Announcing COBOL, a New Programming Language"
  author: "gracehop",
  title: "Announcing COBOL, a New Programming Language"


Close all infowindows in Google Maps API v3

Declare global variables:

var mapOptions;
var map;
var infowindow;
var marker;
var contentString;
var image;

In intialize use the map's addEvent method:

google.maps.event.addListener(map, 'click', function() {
    if (infowindow) {

How to run Gradle from the command line on Mac bash

Also, if you don't have the gradlew file in your current directory:

You can install gradle with homebrew with the following command:

$ brew install gradle

As mentioned in this answer. Then, you are not going to need to include it in your path (homebrew will take care of that) and you can just run (from any directory):

$ gradle test 

SQL Server date format yyyymmdd


Tested in SQL Server 2012

Function passed as template argument

Came here with the additional requirement, that also parameter/return types should vary. Following Ben Supnik this would be for some type T

typedef T(*binary_T_op)(T, T);

instead of

typedef int(*binary_int_op)(int, int);

The solution here is to put the function type definition and the function template into a surrounding struct template.

template <typename T> struct BinOp
    typedef T(*binary_T_op )(T, T); // signature for all valid template params
    template<binary_T_op op>
    T do_op(T a, T b)
       return op(a,b);

double mulDouble(double a, double b)
    return a * b;

BinOp<double> doubleBinOp;

double res = doubleBinOp.do_op<&mulDouble>(4, 5);

Alternatively BinOp could be a class with static method template do_op(...), then called as

double res = BinOp<double>::do_op<&mulDouble>(4, 5);

How do I choose grid and block dimensions for CUDA kernels?

The blocksize is usually selected to maximize the "occupancy". Search on CUDA Occupancy for more information. In particular, see the CUDA Occupancy Calculator spreadsheet.

Listing information about all database files in SQL Server

If you want get location of Database you can check Get All DBs Location.
you can use sys.master_files for get location of db and sys.databse to get db name

    type_desc AS FileType,
    Physical_Name AS Location
    sys.master_files mf
    sys.databases db ON db.database_id = mf.database_id

How to use the read command in Bash?

The read in your script command is fine. However, you execute it in the pipeline, which means it is in a subshell, therefore, the variables it reads to are not visible in the parent shell. You can either

  • move the rest of the script in the subshell, too:

    echo hello | { read str
      echo $str
  • or use command substitution to get the value of the variable out of the subshell

    str=$(echo hello)
    echo $str

    or a slightly more complicated example (Grabbing the 2nd element of ls)

    str=$(ls | { read a; read a; echo $a; })
    echo $str

Init method in Spring Controller (annotation version)

There are several ways to intercept the initialization process in Spring. If you have to initialize all beans and autowire/inject them there are at least two ways that I know of that will ensure this. I have only testet the second one but I belive both work the same.

If you are using @Bean you can reference by initMethod, like this.

public class BeanConfiguration {

  public BeanA beanA() {
    return new BeanA();

public class BeanA {

  // method to be initialized after context is ready
  public void init() {


If you are using @Component you can annotate with @EventListener like this.

public class BeanB {

  public void onApplicationEvent(ContextRefreshedEvent event) {

In my case I have a legacy system where I am now taking use of IoC/DI where Spring Boot is the choosen framework. The old system brings many circular dependencies to the table and I therefore must use setter-dependency a lot. That gave me some headaches since I could not trust @PostConstruct since autowiring/injection by setter was not yet done. The order is constructor, @PostConstruct then autowired setters. I solved it with @EventListener annotation which wil run last and at the "same" time for all beans. The example shows implementation of InitializingBean aswell.

I have two classes (@Component) with dependency to each other. The classes looks the same for the purpose of this example displaying only one of them.

public class BeanA implements InitializingBean {
  private BeanB beanB;

  public BeanA() {

  private void postConstruct() {

  public void setBeanB(BeanB beanB) {
    log.debug("@Autowired beanB");
    this.beanB = beanB;

  public void afterPropertiesSet() throws Exception {

  public void onApplicationEvent(ContextRefreshedEvent event) {

This is the log output showing the order of the calls when the container starts.

2018-11-30 18:29:30.504 DEBUG 3624 --- [           main] com.example.demo.BeanA                   : Created...
2018-11-30 18:29:30.509 DEBUG 3624 --- [           main] com.example.demo.BeanB                   : Created...
2018-11-30 18:29:30.517 DEBUG 3624 --- [           main] com.example.demo.BeanB                   : @Autowired beanA
2018-11-30 18:29:30.518 DEBUG 3624 --- [           main] com.example.demo.BeanB                   : @PostConstruct
2018-11-30 18:29:30.518 DEBUG 3624 --- [           main] com.example.demo.BeanB                   : afterPropertiesSet()
2018-11-30 18:29:30.518 DEBUG 3624 --- [           main] com.example.demo.BeanA                   : @Autowired beanB
2018-11-30 18:29:30.518 DEBUG 3624 --- [           main] com.example.demo.BeanA                   : @PostConstruct
2018-11-30 18:29:30.518 DEBUG 3624 --- [           main] com.example.demo.BeanA                   : afterPropertiesSet()
2018-11-30 18:29:30.607 DEBUG 3624 --- [           main] com.example.demo.BeanA                   : @EventListener
2018-11-30 18:29:30.607 DEBUG 3624 --- [           main] com.example.demo.BeanB                   : @EventListener

As you can see @EventListener is run last after everything is ready and configured.

How to run Pip commands from CMD

Make sure to also add "C:\Python27\Scripts" to your path. pip.exe should be in that folder. Then you can just run:

C:\> pip install modulename

How do I bind a List<CustomObject> to a WPF DataGrid?

You dont need to give column names manually in xaml. Just set AutoGenerateColumns property to true and your list will be automatically binded to DataGrid. refer code. XAML Code:

    <DataGrid x:Name="MyDatagrid" AutoGenerateColumns="True" Height="447" HorizontalAlignment="Left" Margin="20,85,0,0" VerticalAlignment="Top" Width="799"  ItemsSource="{Binding Path=ListTest, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"  CanUserAddRows="False"> </Grid>


Public Class Test 
    public string m_field1_Test{get;set;}
    public string m_field2_Test { get; set; }
    public Test()
        m_field1_Test = "field1";
        m_field2_Test = "field2";
    public MainWindow()

        listTest = new List<Test>();

        for (int i = 0; i < 10; i++)
            obj = new Test();


        this.MyDatagrid.ItemsSource = ListTest;



How to use ImageBackground to set background image for screen in react-native

i achieved this by:

import { ImageBackground } from 'react-native';

<ImageBackground style={ styles.imgBackground } 

   //place your now nested component JSX code here


And then the Styles:

imgBackground: {
        width: '100%',
        height: '100%',
        flex: 1 

Joining three tables using MySQL

Use this:

SELECT AS Student, AS Course 
FROM student s 
  LEFT JOIN (bridge b CROSS JOIN course c) 
    ON ( = b.sid AND b.cid =;

CURL to access a page that requires a login from a different page

My answer is a mod of some prior answers from @JoeMills and @user.

  1. Get a cURL command to log into server:

    • Load login page for website and open Network pane of Developer Tools
      • In firefox, right click page, choose 'Inspect Element (Q)' and click on Network tab
    • Go to login form, enter username, password and log in
    • After you have logged in, go back to Network pane and scroll to the top to find the POST entry. Right click and choose Copy -> Copy as CURL
    • Paste this to a text editor and try this in command prompt to see if it works
      • Its possible that some sites have hardening that will block this type of login spoofing that would require more steps below to bypass.
  2. Modify cURL command to be able to save session cookie after login

    • Remove the entry -H 'Cookie: <somestuff>'
    • Add after curl at beginning -c login_cookie.txt
    • Try running this updated curl command and you should get a new file 'login_cookie.txt' in the same folder
  3. Call a new web page using this new cookie that requires you to be logged in

    • curl -b login_cookie.txt <url_that_requires_log_in>

I have tried this on Ubuntu 20.04 and it works like a charm.

CSS /JS to prevent dragging of ghost image?

Tested on Firefox: removing and putting back the image works! And it's transparent at the execution, too. For instance,

$('.imageContainerClass').mousedown(function() {
    var id = $(this).attr('id');
    $('#'+id).append('Image tag code');

EDIT: This works only on IE and on Firefox, strangely. I also added draggable = false on each image. Still a ghost with Chrome and Safari.

EDIT 2: The background-image solution is genuinely the best one. The only subtlety is that the background-size property has to be redefined every time the background-image is changed! Or so, that's what it looked like from my side. Better still, I had an issue with normal img tags under IE, where IE failed to resize the images. Now, the images have the correct dimensions. Simple:

$(id).css( 'background-image', url('blah.png') );
$(id).css( 'background-size', '40px');

Also, perhaps consider those:

background-Position: center center;

Get top n records for each group of grouped results

There is a really nice answer to this problem at MySQL - How To Get Top N Rows per Each Group

Based on the solution in the referenced link, your query would be like:

SELECT Person, Group, Age
     (SELECT Person, Group, Age, 
                  @group_rank := IF(@group = Group, @group_rank + 1, 1) AS group_rank,
                  @current_group := Group 
       FROM `your_table`
       ORDER BY Group, Age DESC
     ) ranked
   WHERE group_rank <= `n`
   ORDER BY Group, Age DESC;

where n is the top n and your_table is the name of your table.

I think the explanation in the reference is really clear. For quick reference I will copy and paste it here:

Currently MySQL does not support ROW_NUMBER() function that can assign a sequence number within a group, but as a workaround we can use MySQL session variables.

These variables do not require declaration, and can be used in a query to do calculations and to store intermediate results.

@current_country := country This code is executed for each row and stores the value of country column to @current_country variable.

@country_rank := IF(@current_country = country, @country_rank + 1, 1) In this code, if @current_country is the same we increment rank, otherwise set it to 1. For the first row @current_country is NULL, so rank is also set to 1.

For correct ranking, we need to have ORDER BY country, population DESC

std::string formatting like sprintf

I wrote my own using vsnprintf so it returns string instead of having to create my own buffer.

#include <string>
#include <cstdarg>

//missing string printf
//this is safe and convenient but not exactly efficient
inline std::string format(const char* fmt, ...){
    int size = 512;
    char* buffer = 0;
    buffer = new char[size];
    va_list vl;
    va_start(vl, fmt);
    int nsize = vsnprintf(buffer, size, fmt, vl);
    if(size<=nsize){ //fail delete buffer and try again
        delete[] buffer;
        buffer = 0;
        buffer = new char[nsize+1]; //+1 for /0
        nsize = vsnprintf(buffer, size, fmt, vl);
    std::string ret(buffer);
    delete[] buffer;
    return ret;

So you can use it like

std::string mystr = format("%s %d %10.5f", "omg", 1, 10.5);

Alphanumeric, dash and underscore but no spaces regular expression check JavaScript

You shouldn't use String.match but RegExp.prototype.test (i.e. /abc/.test("abcd")) instead of if you're only interested in a boolean value. You also need to repeat your character class as explained in the answer by Andy E:

var regexp = /^[a-zA-Z0-9-_]+$/;

Eclipse+Maven src/main/java not visible in src folder in Package Explorer

I have solved this issue by below steps:

Right click the Maven Project -> Build Path -> Configure Build Path In Order and Export tab, you can see the message like '2 build path entries are missing' Now select 'JRE System Library' and 'Maven Dependencies' checkbox Click OK Now you can see below in all type of Explorers (Package or Project or Navigator)

Iptables setting multiple multiports in one rule

You need to use multiple rules to implement OR-like semantics, since matches are always AND-ed together within a rule. Alternatively, you can do matching against port-indexing ipsets (ipset create blah bitmap:port).

How do I remove quotes from a string?

str_replace('"', "", $string);
str_replace("'", "", $string);

I assume you mean quotation marks?

Otherwise, go for some regex, this will work for html quotes for example:

preg_replace("/<!--.*?-->/", "", $string);

C-style quotes:

preg_replace("/\/\/.*?\n/", "\n", $string);

CSS-style quotes:

preg_replace("/\/*.*?\*\//", "", $string);

bash-style quotes:

preg-replace("/#.*?\n/", "\n", $string);

Etc etc...

Unfamiliar symbol in algorithm: what does ? mean?

The upside-down A symbol is the universal quantifier from predicate logic. (Also see the more complete discussion of the first-order predicate calculus.) As others noted, it means that the stated assertions holds "for all instances" of the given variable (here, s). You'll soon run into its sibling, the backwards capital E, which is the existential quantifier, meaning "there exists at least one" of the given variable conforming to the related assertion.

If you're interested in logic, you might enjoy the book Logic and Databases: The Roots of Relational Theory by C.J. Date. There are several chapters covering these quantifiers and their logical implications. You don't have to be working with databases to benefit from this book's coverage of logic.

How to assign the output of a Bash command to a variable?

You can also do way more complex commands, just to round out the examples above. So, say I want to get the number of processes running on the system and store it in the ${NUM_PROCS} variable.

All you have to so is generate the command pipeline and stuff it's output (the process count) into the variable.

It looks something like this:

NUM_PROCS=$(ps -e | sed 1d | wc -l)

I hope that helps add some handy information to this discussion.

Reading multiple Scanner inputs

If every input asks the same question, you should use a for loop and an array of inputs:

Scanner dd = new Scanner(;
int[] vars = new int[3];

for(int i = 0; i < vars.length; i++) {
  System.out.println("Enter next var: ");
  vars[i] = dd.nextInt();

Or as Chip suggested, you can parse the input from one line:

Scanner in = new Scanner(;
int[] vars = new int[3];

System.out.println("Enter "+vars.length+" vars: ");
for(int i = 0; i < vars.length; i++)
  vars[i] = in.nextInt();

You were on the right track, and what you did works. This is just a nicer and more flexible way of doing things.

Why isn't textarea an input[type="textarea"]?

It was a limitation of the technology at the time it was created. My answer copied over from Programmers.SE:

From one of the original HTML drafts:

NOTE: In the initial design for forms, multi-line text fields were supported by the Input element with TYPE=TEXT. Unfortunately, this causes problems for fields with long text values. SGML's default (Reference Quantity Set) limits the length of attribute literals to only 240 characters. The HTML 2.0 SGML declaration increases the limit to 1024 characters.

Regular expression to check if password is "8 characters including 1 uppercase letter, 1 special character, alphanumeric characters"

The answer is to not use a regular expression. This is sets and counting.

Regular expressions are about order.

In your life as a programmer you will asked to do many things that do not make sense. Learn to dig a level deeper. Learn when the question is wrong.

The question (if it mentioned regular expressions) is wrong.

Pseudocode (been switching between too many languages, of late):

if s.length < 8:
    return False
nUpper = nLower = nAlphanum = nSpecial = 0
for c in s:
    if isUpper(c):
    if isLower(c):
    if isAlphanumeric(c):
    if isSpecial(c):
return (0 < nUpper) and (0 < nAlphanum) and (0 < nSpecial)

Bet you read and understood the above code almost instantly. Bet you took much longer with the regex, and are less certain it is correct. Extending the regex is risky. Extended the immediate above, much less so.

Note also the question is imprecisely phrased. Is the character set ASCII or Unicode, or ?? My guess from reading the question is that at least one lowercase character is assumed. So I think the assumed last rule should be:

return (0 < nUpper) and (0 < nLower) and (0 < nAlphanum) and (0 < nSpecial)

(Changing hats to security-focused, this is a really annoying/not useful rule.)

Learning to know when the question is wrong is massively more important than clever answers. A clever answer to the wrong question is almost always wrong.

How to find the Windows version from the PowerShell command line

Using Windows Powershell, it possible to get the data you need in the following way


(Get-WmiObject -class Win32_OperatingSystem).Caption


(Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion" -Name ReleaseId).ReleaseId


(Get-CimInstance Win32_OperatingSystem).version

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

This feature already exists in Ubuntu and Debian, in the command-not-found package.

Multi-threading in VBA

Can't be done natively with VBA. VBA is built in a single-threaded apartment. The only way to get multiple threads is to build a DLL in something other than VBA that has a COM interface and call it from VBA.

INFO: Descriptions and Workings of OLE Threading Models

How do I format {{$timestamp}} as MM/DD/YYYY in Postman?

You could use moment.js with Postman to give you that timestamp format.

You can add this to the pre-request script:

const moment = require('moment');
pm.globals.set("today", moment().format("MM/DD/YYYY"));

Then reference {{today}} where ever you need it.

If you add this to the Collection Level Pre-request Script, it will be run for each request in the Collection. Rather than needing to add it to all the requests individually.

For more information about using moment in Postman, I wrote a short blog post:

Why when I transfer a file through SFTP, it takes longer than FTP?

SFTP will almost always be significantly slower than FTP or FTPS (usually by several orders of magnitude). The reason for the difference is that there is a lot of additional packet, encryption and handshaking overhead inherent in the SSH2 protocol that FTP doesn't have to worry about. FTP is a very lean and comparatively simple protocol with almost no data transfer overhead, and the protocol was specifically designed for transferring files quickly. Encryption will slow FTP down, but not nearly to the level of SFTP.

SFTP runs over SSH2 and is much more susceptible to network latency and client and server machine resource constraints. This increased susceptibility is due to the extra data handshaking involved with every packet sent between the client and server, and with the additional complexity inherent in decoding an SSH2 packet. SSH2 was designed as a replacement for Telnet and other insecure remote shells, not for very high speed communications. The flexibility that SSH2 provides for securely packaging and transferring almost any type of data also contributes a great deal of additional complexity and overhead to the protocol.

However, it is still possible to get a data transfer rate of several MB/s between client and server using SFTP if the right network conditions are present. The following are items to check when trying to maximize SFTP transfer speeds:

Is there a firewall or network device inspecting or throttling SSH2 traffic on your network? That might be slowing things down. Check you firewall settings. We've had users report solving extremely slow SFTP file transfers by modifying their firewall rules. The SFTP client you use can make a big difference. Try several different SFTP clients and see if you get different results. Network latency will drastically affect SFTP. If the link you are on has a high degree of latency then that is going to be a problem for fast transfers. How powerful is the server machine? Encryption with SFTP is very intensive. Make sure you have a sufficiently powerful machine that isn't being overtaxed during SFTP file transfers (high CPU utilization).

See more:

How to implement a Navbar Dropdown Hover in Bootstrap v4?

Andrei's "complete" jQuery+CSS solution has the right intent, but it's verbose and still incomplete. Incomplete because while it probably covers all the necessary DOM changes, it's missing the firing of custom events. Verbose because it's wheel-reinventing when Bootstrap already provides the dropdown() method, which does everything.

So the correct, DRY solution, which does not rely on the CSS hack often repeated among other answers, is just jQuery:

$('body').on('mouseover mouseout', '.dropdown', function(e) {

JSON Structure for List of Objects

The first one is invalid syntax. You cannot have object properties inside a plain array. The second one is right although it is not strict JSON. It's a relaxed form of JSON wherein quotes in string keys are omitted.

This tutorial by Patrick Hunlock, may help to learn about JSON and this site may help to validate JSON.

Appending the same string to a list of strings in Python

Updating with more options

list1 = ['foo', 'fob', 'faz', 'funk']
addstring = 'bar'
for index, value in enumerate(list1):
    list1[index] = addstring + value #this will prepend the string
    #list1[index] = value + addstring this will append the string

Avoid using keywords as variables like 'list', renamed 'list' as 'list1' instead

How do I grep for all non-ASCII characters?

The following works for me:

grep -P "[\x80-\xFF]" file.xml

Non-ASCII characters start at 0x80 and go to 0xFF when looking at bytes. Grep (and family) don't do Unicode processing to merge multi-byte characters into a single entity for regex matching as you seem to want. The -P option in my grep allows the use of \xdd escapes in character classes to accomplish what you want.

Substring in VBA



What are the pros and cons of parquet format compared to other formats?

I think the main difference I can describe relates to record oriented vs. column oriented formats. Record oriented formats are what we're all used to -- text files, delimited formats like CSV, TSV. AVRO is slightly cooler than those because it can change schema over time, e.g. adding or removing columns from a record. Other tricks of various formats (especially including compression) involve whether a format can be split -- that is, can you read a block of records from anywhere in the dataset and still know it's schema? But here's more detail on columnar formats like Parquet.

Parquet, and other columnar formats handle a common Hadoop situation very efficiently. It is common to have tables (datasets) having many more columns than you would expect in a well-designed relational database -- a hundred or two hundred columns is not unusual. This is so because we often use Hadoop as a place to denormalize data from relational formats -- yes, you get lots of repeated values and many tables all flattened into a single one. But it becomes much easier to query since all the joins are worked out. There are other advantages such as retaining state-in-time data. So anyway it's common to have a boatload of columns in a table.

Let's say there are 132 columns, and some of them are really long text fields, each different column one following the other and use up maybe 10K per record.

While querying these tables is easy with SQL standpoint, it's common that you'll want to get some range of records based on only a few of those hundred-plus columns. For example, you might want all of the records in February and March for customers with sales > $500.

To do this in a row format the query would need to scan every record of the dataset. Read the first row, parse the record into fields (columns) and get the date and sales columns, include it in your result if it satisfies the condition. Repeat. If you have 10 years (120 months) of history, you're reading every single record just to find 2 of those months. Of course this is a great opportunity to use a partition on year and month, but even so, you're reading and parsing 10K of each record/row for those two months just to find whether the customer's sales are > $500.

In a columnar format, each column (field) of a record is stored with others of its kind, spread all over many different blocks on the disk -- columns for year together, columns for month together, columns for customer employee handbook (or other long text), and all the others that make those records so huge all in their own separate place on the disk, and of course columns for sales together. Well heck, date and months are numbers, and so are sales -- they are just a few bytes. Wouldn't it be great if we only had to read a few bytes for each record to determine which records matched our query? Columnar storage to the rescue!

Even without partitions, scanning the small fields needed to satisfy our query is super-fast -- they are all in order by record, and all the same size, so the disk seeks over much less data checking for included records. No need to read through that employee handbook and other long text fields -- just ignore them. So, by grouping columns with each other, instead of rows, you can almost always scan less data. Win!

But wait, it gets better. If your query only needed to know those values and a few more (let's say 10 of the 132 columns) and didn't care about that employee handbook column, once it had picked the right records to return, it would now only have to go back to the 10 columns it needed to render the results, ignoring the other 122 of the 132 in our dataset. Again, we skip a lot of reading.

(Note: for this reason, columnar formats are a lousy choice when doing straight transformations, for example, if you're joining all of two tables into one big(ger) result set that you're saving as a new table, the sources are going to get scanned completely anyway, so there's not a lot of benefit in read performance, and because columnar formats need to remember more about the where stuff is, they use more memory than a similar row format).

One more benefit of columnar: data is spread around. To get a single record, you can have 132 workers each read (and write) data from/to 132 different places on 132 blocks of data. Yay for parallelization!

And now for the clincher: compression algorithms work much better when it can find repeating patterns. You could compress AABBBBBBCCCCCCCCCCCCCCCC as 2A6B16C but ABCABCBCBCBCCCCCCCCCCCCCC wouldn't get as small (well, actually, in this case it would, but trust me :-) ). So once again, less reading. And writing too.

So we read a lot less data to answer common queries, it's potentially faster to read and write in parallel, and compression tends to work much better.

Columnar is great when your input side is large, and your output is a filtered subset: from big to little is great. Not as beneficial when the input and outputs are about the same.

But in our case, Impala took our old Hive queries that ran in 5, 10, 20 or 30 minutes, and finished most in a few seconds or a minute.

Hope this helps answer at least part of your question!

post ajax data to PHP and return data

So what does count_votes look like? Is it a script? Anything that you want to get back from an ajax call can be retrieved using a simple echo (of course you could use JSON or xml, but for this simple example you would just need to output something in count_votes.php like:

$id = $_POST['id'];

function getVotes($id){
    // call your database here
    $query = ("SELECT votes FROM poll WHERE ID = $id");
    $result = @mysql_query($query);
    $row = mysql_fetch_row($result);

    return $row->votes;
$votes = getVotes($id);
echo $votes;

This is just pseudocode, but should give you the idea. What ever you echo from count_votes will be what is returned to "data" in your ajax call.

OpenCV error: the function is not implemented

Don't waste your time trying to resolve this issue, this was made clear by the makers themselves. Instead of cv2.imshow() use this:

img = cv2.imread('path_to_image')
plt.imshow(img, cmap = 'gray', interpolation = 'bicubic')
plt.xticks([]), plt.yticks([])  # to hide tick values on X and Y axis

How to display 3 buttons on the same line in css

Do something like this,


<div style="width:500px;">
    <button type="submit" class="msgBtn" onClick="return false;" >Save</button>
    <button type="submit" class="msgBtn2" onClick="return false;">Publish</button>
    <button class="msgBtnBack">Back</button>


div button{

Fiddle Demo



<div style="width:500px;" id="container">
    <div><button type="submit" class="msgBtn" onClick="return false;" >Save</button></div>
    <div><button type="submit" class="msgBtn2" onClick="return false;">Publish</button></div>
    <div><button class="msgBtnBack">Back</button></div>


#container div{

Fiddle Demo

Triangle Draw Method

There is not a drawTriangle method neither in Graphics nor Graphics2D. You need to do it by yourself. You can draw three lines using the drawLine method or use one these methods:

These methods work with polygons. You may change the prefix draw to fill when you want to fill the polygon defined by the point set. I inserted the documentation links. Take a look to learn how to use them.

There is the GeneralPath class too. It can be used with Graphics2D, which is capable to draw Shapes. Take a look:

How to execute two mysql queries as one in PHP/MYSQL?

As others have answered, the mysqli API can execute multi-queries with the msyqli_multi_query() function.

For what it's worth, PDO supports multi-query by default, and you can iterate over the multiple result sets of your multiple queries:

$stmt = $dbh->prepare("
    select sql_calc_found_rows * from foo limit 1 ; 
    select found_rows()");
do {
  while ($row = $stmt->fetch()) {
} while ($stmt->nextRowset());

However, multi-query is pretty widely considered a bad idea for security reasons. If you aren't careful about how you construct your query strings, you can actually get the exact type of SQL injection vulnerability shown in the classic "Little Bobby Tables" XKCD cartoon. When using an API that restrict you to single-query, that can't happen.

PHP get domain name

To answer your question, these should work as long as:

  • Your HTTP server passes these values along to PHP (I don't know any that don't)
  • You're not accessing the script via command line (CLI)

But, if I remember correctly, these values can be faked to an extent, so it's best not to rely on them.

My personal preference is to set the domain name as an environment variable in the apache2 virtual host:

# Virtual host

And read it in PHP:

// PHP
echo getenv(DOMAIN_NAME);

This, however, isn't applicable in all circumstances.

TypeError: 'str' does not support the buffer interface

For Django in django.test.TestCase unit testing, I changed my Python2 syntax:

def test_view(self):
    response = self.client.get(reverse('myview'))
    self.assertIn(str(, response.content)

To use the Python3 .decode('utf8') syntax:

def test_view(self):
    response = self.client.get(reverse('myview'))
    self.assertIn(str(, response.content.decode('utf8'))

What method in the String class returns only the first N characters?

Partially for the sake of summarization (excluding LINQ solution), here's two one-liners that address the int maxLength caveat of allowing negative values and also the case of null string:

  1. The Substring way (from Paul Ruane's answer):
public static string Truncate(this string s, uint maxLength) =>
    s?.Substring(0, Math.Min(s.Length, (int)maxLength));
  1. The Remove way (from kbrimington's answer):
public static string Truncate(this string s, uint maxLength) =>
    s?.Length > maxLength ? s.Remove((int)maxLength) : s;

Pretty-Print JSON Data to a File using Python

You can parse the JSON, then output it again with indents like this:

import json
mydata = json.loads(output)
print json.dumps(mydata, indent=4)

See for more info.

How to set up java logging using a properties file? (java.util.logging)

I have tried your code in above code don't use [preferences.load(configFile);] statement and it will is running sample code

public static void main(String[]s)

    Logger log = Logger.getLogger("MyClass");
    try {
    FileInputStream fis =  new FileInputStream("");
    log.addHandler(new java.util.logging.ConsoleHandler());
    log.setUseParentHandlers(false);"starting myApp");

    catch(IOException e) {

How to override and extend basic Django admin templates?

You can use django-overextends, which provides circular template inheritance for Django.

It comes from the Mezzanine CMS, from where Stephen extracted it into a standalone Django extension.

More infos you find in "Overriding vs Extending Templates" (http:/ inside the Mezzanine docs.

For deeper insides look at Stephens Blog "Circular Template Inheritance for Django" (http:/

And in Google Groups the discussion (https:/!topic/mezzanine-users/sUydcf_IZkQ) which started the development of this feature.


I don't have the reputation to add more than 2 links. But I think the links provide interesting background information. So I just left out a slash after "http(s):". Maybe someone with better reputation can repair the links and remove this note.

How to Calculate Jump Target Address and Branch Target Address?

For small functions like this you could just count by hand how many hops it is to the target, from the instruction under the branch instruction. If it branches backwards make that hop number negative. if that number doesn't require all 16 bits, then for every number to the left of the most significant of your hop number, make them 1's, if the hop number is positive make them all 0's Since most branches are close to they're targets, this saves you a lot of extra arithmetic for most cases.

  • chris

What does "for" attribute do in HTML <label> tag?

In a nutshell what it does is refer to the id of the input, that's all:

<label for="the-id-of-the-input">Input here:</label>
<input type="text" name="the-name-of-input" id="the-id-of-the-input">

How to remove the bottom border of a box with CSS

Just add in: border-bottom: none;

#index-03 {
    border: .1px solid #900;
    border-bottom: none;

Parse JSON String to JSON Object in C#.NET

Another choice besides JObject is System.Json.JsonValue for Weak-Typed JSON object.

It also has a JsonValue blob = JsonValue.Parse(json); you can use. The blob will most likely be of type JsonObject which is derived from JsonValue, but could be JsonArray. Check the blob.JsonType if you need to know.

And to answer you question, YES, you may replace json with the name of your actual variable that holds the JSON string. ;-D

There is a System.Json.dll you should add to your project References.


how to prevent this error : Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in ... on line 11

The proper syntax is (in example):

$query = mysql_query('SELECT * FROM beer ORDER BY quality');
while($row = mysql_fetch_assoc($query)) $results[] = $row;

Join two sql queries

I would just use a Union

In your second query add the extra column name and add a '' in all the corresponding locations in the other queries


//reverse order to get the column names
select top 10 personId, '' from Telephone//No Column name assigned 
select top 10 personId, loanId from loan

Create a mocked list by mockito

OK, this is a bad thing to be doing. Don't mock a list; instead, mock the individual objects inside the list. See Mockito: mocking an arraylist that will be looped in a for loop for how to do this.

Also, why are you using PowerMock? You don't seem to be doing anything that requires PowerMock.

But the real cause of your problem is that you are using when on two different objects, before you complete the stubbing. When you call when, and provide the method call that you are trying to stub, then the very next thing you do in either Mockito OR PowerMock is to specify what happens when that method is called - that is, to do the thenReturn part. Each call to when must be followed by one and only one call to thenReturn, before you do any more calls to when. You made two calls to when without calling thenReturn - that's your error.

Insert variable into Header Location PHP

Try using double quotes and keeping the L in location lowercase...


or for example


No need to concatenate here to insert variables.

Convert Array to Object

If you can use Map or Object.assign, it's very easy.

Create an array:

const languages = ['css', 'javascript', 'php', 'html'];

The below creates an object with index as keys:

Object.assign({}, languages)

Replicate the same as above with Maps

Converts to an index based object {0 : 'css'} etc...

const indexMap = new Map(, i) => [i, name] ));
indexMap.get(1) // javascript

Convert to an value based object {css : 'css is great'} etc...

const valueMap = new Map( => [name, `${name} is great!`] ));
valueMap.get('css') // css is great

How can I remove item from querystring in using c#?

You don't make it clear whether you're trying to modify the Querystring in place in the Request object. Since that property is read-only, I guess we'll assume you just want to mess with the string.

... In which case, it's borderline trivial.

  • grab the querystring off the Request
  • .split() it on '&'
  • put it back together into a new string, while sniffing for and tossing out anything starting with "language"

getApplication() vs. getApplicationContext()

To answer the question, getApplication() returns an Application object and getApplicationContext() returns a Context object. Based on your own observations, I would assume that the Context of both are identical (i.e. behind the scenes the Application class calls the latter function to populate the Context portion of the base class or some equivalent action takes place). It shouldn't really matter which function you call if you just need a Context.

Generate random array of floats between a range

The for loop in list comprehension takes time and makes it slow. It is better to use numpy parameters (low, high, size, ..etc)

import numpy as np
import time
rang = 10000
tic = time.time()
for i in range(rang):
    sampl = np.random.uniform(low=0, high=2, size=(182))
print("it took: ", time.time() - tic)

tic = time.time()
for i in range(rang):
    ran_floats = [np.random.uniform(0,2) for _ in range(182)]
print("it took: ", time.time() - tic)

sample output:

('it took: ', 0.06406784057617188)

('it took: ', 1.7253198623657227)

What is the javascript filename naming convention?

I generally prefer hyphens with lower case, but one thing not yet mentioned is that sometimes it's nice to have the file name exactly match the name of a single module or instantiable function contained within.

For example, I have a revealing module declared with var knockoutUtilityModule = function() {...} within its own file named knockoutUtilityModule.js, although objectively I prefer knockout-utility-module.js.

Similarly, since I'm using a bundling mechanism to combine scripts, I've taken to defining instantiable functions (templated view models etc) each in their own file, C# style, for maintainability. For example, ProductDescriptorViewModel lives on its own inside ProductDescriptorViewModel.js (I use upper case for instantiable functions).

C pass int array pointer as parameter into a function

Make use of *(B) instead of *B[0]. Here, *(B+i) implies B[i] and *(B) implies B[0], that is

#include <stdio.h>

int func(int *B){
    *B = 5;     
    // if you want to modify ith index element in the array just do *(B+i)=<value>

int main(void){

    int B[10] = {};
    printf("b[0] = %d\n\n", B[0]);
    printf("b[0] = %d\n\n", B[0]);
    return 0;

How do I get the directory from a file's full path?

If you are working with a FileInfo object, then there is an easy way to extract a string representation of the directory's full path via the DirectoryName property.

Description of the FileInfo.DirectoryName Property via MSDN:

Gets a string representing the directory's full path.

Sample usage:

string filename = @"C:\MyDirectory\MyFile.bat";
FileInfo fileInfo = new FileInfo(filename);
string directoryFullPath = fileInfo.DirectoryName; // contains "C:\MyDirectory"

Link to the MSDN documentation.

How to get child process from parent process

I've written a script to get all child process pids of a parent process. Here is the code. Hope it will help.

function getcpid() {
    cpids=`pgrep -P $1|xargs`
#    echo "cpids=$cpids"
    for cpid in $cpids;
        echo "$cpid"
        getcpid $cpid

getcpid $1

ASP.NET MVC controller actions that return JSON or partial html

Alternative solution with incoding framework

Action return json


    public ActionResult SomeActionMethod()
        return IncJson(new SomeVm(){Id = 1,Name ="Inc"});

Razor page

@using (var template = Html.Incoding().ScriptTemplate<SomeVm>("tmplId"))
    using (var each = template.ForEach())
        <span> Id: @each.For(r=>r.Id) Name: @each.For(r=>r.Name)</span>

  .OnSuccess(dsl => dsl.Self().Core()

Action return html


    public ActionResult SomeActionMethod()
        return IncView();

Razor page

  .OnSuccess(dsl => dsl.Self().Core().Insert.Html())

jQuery to remove an option from drop down list, given option's text/value

$('#id option').remove();

This will clear the Drop Down list. if you want to clear to select value then $("#id option:selected").remove();

Checkbox for nullable boolean

The cleanest approach I could come up with is to expand the extensions available to HtmlHelper while still reusing functionality provided by the framework.

public static MvcHtmlString CheckBoxFor<T>(this HtmlHelper<T> htmlHelper, Expression<Func<T, bool?>> expression, IDictionary<string, object> htmlAttributes) {

    ModelMetadata modelMeta = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
    bool? value = (modelMeta.Model as bool?);

    string name = ExpressionHelper.GetExpressionText(expression);

    return htmlHelper.CheckBox(name, value ?? false, htmlAttributes);

I experimented with 'shaping' the expression to allow a straight pass through to the native CheckBoxFor<Expression<Func<T, bool>>> but I don't think it's possible.

Why won't my PHP app send a 404 error?

A little bit shorter version. Suppress odd echo.

if (strstr($_SERVER['REQUEST_URI'],'index.php')){
  header('HTTP/1.0 404 Not Found');
  exit("<h1>404 Not Found</h1>\nThe page that you have requested could not be found.");

PHP mPDF save file as PDF

Try this:



D - means Download
F - means File-save only

iOS Safari – How to disable overscroll but allow scrollable divs to scroll normally?

this one works for me (plain javascript)

var fixScroll = function (className, border) {  // className = class of scrollElement(s), border: borderTop + borderBottom, due to offsetHeight
var reg = new RegExp(className,"i"); var off = +border + 1;
function _testClass(e) { var o =; while (!reg.test(o.className)) if (!o || o==document) return false; else o = o.parentNode; return o;}
document.ontouchmove  = function(e) { var o = _testClass(e); if (o) { e.stopPropagation(); if (o.scrollTop == 0) { o.scrollTop += 1; e.preventDefault();}}}
document.ontouchstart = function(e) { var o = _testClass(e); if (o && o.scrollHeight >= o.scrollTop + o.offsetHeight - off) o.scrollTop -= off;}

fixScroll("fixscroll",2); // assuming I have a 1px border in my DIV


<div class="fixscroll" style="border:1px gray solid">content</div>

How to play .wav files with java

A class that will play a WAV file, blocking until the sound has finished playing:

class Sound implements Playable {

    private final Path wavPath;
    private final CyclicBarrier barrier = new CyclicBarrier(2);

    Sound(final Path wavPath) {

        this.wavPath = wavPath;

    public void play() throws LineUnavailableException, IOException, UnsupportedAudioFileException {

        try (final AudioInputStream audioIn = AudioSystem.getAudioInputStream(wavPath.toFile());
             final Clip clip = AudioSystem.getClip()) {


    private void listenForEndOf(final Clip clip) {

        clip.addLineListener(event -> {
            if (event.getType() == LineEvent.Type.STOP) waitOnBarrier();

    private void waitOnBarrier() {

        try {

        } catch (final InterruptedException ignored) {
        } catch (final BrokenBarrierException e) {

            throw new RuntimeException(e);

    private void waitForSoundEnd() {


Is there a Google Sheets formula to put the name of the sheet into a cell?

Here is my proposal for a script which returns the name of the sheet from its position in the sheet list in parameter. If no parameter is provided, the current sheet name is returned.

function sheetName(idx) {
  if (!idx)
    return SpreadsheetApp.getActiveSpreadsheet().getActiveSheet().getName();
  else {
    var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets();
    var idx = parseInt(idx);
    if (isNaN(idx) || idx < 1 || sheets.length < idx)
      throw "Invalid parameter (it should be a number from 0 to "+sheets.length+")";
    return sheets[idx-1].getName();

You can then use it in a cell like any function

=sheetName() // display current sheet name
=sheetName(1) // display first sheet name
=sheetName(5) // display 5th sheet name

As described by other answers, you need to add this code in a script with :

Tools > Script editor

How to add a fragment to a programmatically generated layout?

Below is a working code to add a fragment e.g 3 times to a vertical LinearLayout (xNumberLinear). You can change number 3 with any other number or take a number from a spinner!

for (int i = 0; i < 3; i++) {
            LinearLayout linearDummy = new LinearLayout(getActivity());
            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {

                Toast.makeText(getActivity(), "This function works on newer versions of android", Toast.LENGTH_LONG).show();

            } else {
            fragmentManager.beginTransaction().add(linearDummy.getId(), new SomeFragment(),"someTag1").commit();


Get URL query string parameters

I will recommended best answer as

<?php echo 'Hello ' . htmlspecialchars($_GET["name"]) . '!'; ?>

Assuming the user entered

The above example will output:

Hello Hannes!

Why do people hate SQL cursors so much?

Cursors tend to be used by beginning SQL developers in places where set-based operations would be better. Particularly when people learn SQL after learning a traditional programming language, the "iterate over these records" mentality tends to lead people to use cursors inappropriately.

Most serious SQL books include a chapter enjoining the use of cursors; well-written ones make it clear that cursors have their place but shouldn't be used for set-based operations.

There are obviously situations where cursors are the correct choice, or at least A correct choice.

When to use <span> instead <p>?

Semantically speaking, a p is a paragraph tag and should be used to format a paragraph of text. A span is an inline formatting change that isn't handled semantically.

How to check radio button is checked using JQuery?

Radio buttons are,

<input type="radio" id="radio_1" class="radioButtons" name="radioButton" value="1">
<input type="radio" id="radio_2" class="radioButtons" name="radioButton" value="2">

to check on click,

       //logic here

How to communicate between iframe and the parent site?

It must be here, because accepted answer from 2012

In 2018 and modern browsers you can send a custom event from iframe to parent window.


var data = { foo: 'bar' }
var event = new CustomEvent('myCustomEvent', { detail: data })


window.document.addEventListener('myCustomEvent', handleEvent, false)
function handleEvent(e) {
  console.log(e.detail) // outputs: {foo: 'bar'}

PS: Of course, you can send events in opposite direction same way.


Difference between iCalendar (.ics) and the vCalendar (.vcs)

The VCS files can have its information coded in Quoted printable which is a nightmare. The above solution recommending "VCS to ICS Calendar Converter" is the way to go.

Using Apache POI how to read a specific excel column

Please be aware, that iterating through the columns using row cell iterator ( Iterator<Cell> cellIterator = row.cellIterator();) may lead to silent skipping columns. I have just encountered a document that was exposing such behaviour.

Iterating using indexes in a for loop and using row.getCell(i) was not skipping columns and was returning values at the correct column indexes.

Pandas rename column by position?

You can do this:

df.rename(columns={ df.columns[1]: "whatever" })

Docker - a way to give access to a host USB or serial device?

I wanted to extend the answers already given to include support for dynamically connected devices that aren't captured with /dev/bus/usb and how to get this working when using a Windows host along with the boot2docker VM.

If you are working with Windows, you'll need to add any USB rules for devices that you want Docker to access within the VirtualBox manager. To do this you can stop the VM by running:

host:~$ docker-machine stop default

Open the VirtualBox Manager and add USB support with filters as required.

Start the boot2docker VM:

host:~$ docker-machine start default

Since the USB devices are connected to the boot2docker VM, the commands need to be run from that machine. Open up a terminal with the VM and run the docker run command:

host:~$ docker-machine ssh
docker@default:~$ docker run -it --privileged ubuntu bash

Note, when the command is run like this, then only previously connected USB devices will be captures. The volumes flag is only required if you want this to work with devices connected after the container is started. In that case, you can use:

docker@default:~$ docker run -it --privileged -v /dev:/dev ubuntu bash

Note, I had to use /dev instead of /dev/bus/usb in some cases to capture a device like /dev/sg2. I can only assume the same would be true for devices like /dev/ttyACM0 or /dev/ttyUSB0.

The docker run commands will work with a Linux host as well.

How to change font-color for disabled input?

input[disabled], input[disabled]:hover { background-color:#444; }

Could not insert new outlet connection: Could not find any information for the class named

I solved this problem by programmatically creating the Labels and Textfields, and then Command-Dragged from the little empty circles on the left of the code to the components on the Storyboard. To illustrate my point: I wrote @IBOutlet weak var HelloLabel: UILabel!, and then pressed Command and dragged the code into the component on the storyboard.

How do I catch a PHP fatal (`E_ERROR`) error?

I need to handle fatal errors for production to instead show a static styled 503 Service Unavailable HTML output. This is surely a reasonable approach to "catching fatal errors". This is what I've done:

I have a custom error handling function "error_handler" which will display my "503 service unavailable" HTML page on any E_ERROR, E_USER_ERROR, etc. This will now be called on the shutdown function, catching my fatal error,

function fatal_error_handler() {

    if (@is_array($e = @error_get_last())) {
        $code = isset($e['type']) ? $e['type'] : 0;
        $msg = isset($e['message']) ? $e['message'] : '';
        $file = isset($e['file']) ? $e['file'] : '';
        $line = isset($e['line']) ? $e['line'] : '';
        if ($code>0)
            error_handler($code, $msg, $file, $line);

in my custom error_handler function, if the error is E_ERROR, E_USER_ERROR, etc. I also call @ob_end_clean(); to empty the buffer, thus removing PHP's "fatal error" message.

Take important note of the strict isset() checking and @ silencing functions since we don’t want our error_handler scripts to generate any errors.

In still agreeing with keparo, catching fatal errors does defeat the purpose of "FATAL error" so it's not really intended for you to do further processing. Do not run any mail() functions in this shutdown process as you will certainly back up the mail server or your inbox. Rather log these occurrences to file and schedule a cron job to find these error.log files and mail them to administrators.

jQuery Set Cursor Position in Text Area

I do realize that this is a very old post, but I thought that I should offer perhaps a simpler solution to update it using only jQuery.

function getTextCursorPosition(ele) {   
    return ele.prop("selectionStart");

function setTextCursorPosition(ele,pos) {
    ele.prop("selectionStart", pos + 1);
    ele.prop("selectionEnd", pos + 1);

function insertNewLine(text,cursorPos) {
    var firstSlice = text.slice(0,cursorPos);
    var secondSlice = text.slice(cursorPos);

    var new_text = [firstSlice,"\n",secondSlice].join('');

    return new_text;

Usage for using ctrl-enter to add a new line (like in Facebook):

    if (e.keyCode == 13 && !e.ctrlKey) {
        //do something special here with just pressing Enter
    }else if (e.ctrlKey){
        //If the ctrl key was pressed with the Enter key,
        //then enter a new line break into the text
        var cursorPos = getTextCursorPosition($(this));                

        $(this).val(insertNewLine($(this).val(), cursorPos));
        setTextCursorPosition($(this), cursorPos);

I am open to critique. Thank you.

UPDATE: This solution does not allow normal copy and paste functionality to work (i.e. ctrl-c, ctrl-v), so I will have to edit this in the future to make sure that part works again. If you have an idea how to do that, please comment here, and I will be happy to test it out. Thanks.

Change button text from Xcode?

If you've got a button that's hooked up to an action in your code, you can change the title without an instance variable.

For example, if the button is set to this action:


You can simply do this in the method:

-(IBAction)startSomething:(id)sender {
    [sender setTitle:@"Hello" forState:UIControlStateNormal];

Or if you're wanting to toggle the name of the button, you can create a BOOL named "buttonToggled" (for example), and toggle the name this way:

-(IBAction)toggleButton:(id)sender {
    if (!buttonToggled) {
        [sender setTitle:@"Something" forState:UIControlStateNormal];
        buttonToggled = YES;
    else {
        [sender setTitle:@"Different" forState:UIControlStateNormal];
        buttonToggled = NO;

Sleep/Wait command in Batch

Ok, yup you use the timeout command to sleep. But to do the whole process silently, it's not possible with cmd/batch. One of the ways is to create a VBScript that will run the Batch File without opening/showing any window. And here is the script:

Set WshShell = CreateObject("WScript.Shell")
WshShell.Run chr(34) & "PATH OF BATCH FILE WITH QUOTATION MARKS" & Chr(34), 0
Set WshShell = Nothing

Copy and paste the above code on notepad and save it as Anyname.**vbs ** An example of the *"PATH OF BATCH FILE WITH QUOTATION MARKS" * might be: "C:\ExampleFolder\MyBatchFile.bat"

Chaining multiple filter() in Django, is this a bug?

Sometimes you don't want to join multiple filters together like this:

def your_dynamic_query_generator(self, event: Event):
    qs \
    .filter(shiftregistrations__event=event) \

And the following code would actually not return the correct thing.

def your_dynamic_query_generator(self, event: Event):
    return Q(shiftregistrations__event=event) & Q(shiftregistrations__shifts=False)

What you can do now is to use an annotation count-filter.

In this case we count all shifts which belongs to a certain event.

qs: EventQuerySet = qs.annotate(
    num_shifts=Count('shiftregistrations__shifts', filter=Q(shiftregistrations__event=event))

Afterwards you can filter by annotation.

def your_dynamic_query_generator(self):
    return Q(num_shifts=0)

This solution is also cheaper on large querysets.

Hope this helps.

Vagrant shared and synced folders

shared folders VS synced folders

Basically shared folders are renamed to synced folder from v1 to v2 (docs), under the bonnet it is still using vboxsf between host and guest (there is known performance issues if there are large numbers of files/directories).

Vagrantfile directory mounted as /vagrant in guest

Vagrant is mounting the current working directory (where Vagrantfile resides) as /vagrant in the guest, this is the default behaviour.

See docs

NOTE: By default, Vagrant will share your project directory (the directory with the Vagrantfile) to /vagrant.

You can disable this behaviour by adding cfg.vm.synced_folder ".", "/vagrant", disabled: true in your Vagrantfile.

Why synced folder is not working

Based on the output /tmp on host was NOT mounted during up time.

Use VAGRANT_INFO=debug vagrant up or VAGRANT_INFO=debug vagrant reload to start the VM for more output regarding why the synced folder is not mounted. Could be a permission issue (mode bits of /tmp on host should be drwxrwxrwt).

I did a test quick test using the following and it worked (I used opscode bento raring vagrant base box)

config.vm.synced_folder "/tmp", "/tmp/src"


$ vagrant reload
[default] Attempting graceful shutdown of VM...
[default] Setting the name of the VM...
[default] Clearing any previously set forwarded ports...
[default] Creating shared folders metadata...
[default] Clearing any previously set network interfaces...
[default] Available bridged network interfaces:
1) eth0
2) vmnet8
3) lxcbr0
4) vmnet1
What interface should the network bridge to? 1
[default] Preparing network interfaces based on configuration...
[default] Forwarding ports...
[default] -- 22 => 2222 (adapter 1)
[default] Running 'pre-boot' VM customizations...
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] VM booted and ready for use!
[default] Configuring and enabling network interfaces...
[default] Mounting shared folders...
[default] -- /vagrant
[default] -- /tmp/src

Within the VM, you can see the mount info /tmp/src on /tmp/src type vboxsf (uid=900,gid=900,rw).

Inner Joining three tables

dbo.tableA AS A INNER JOIN dbo.TableB AS B
ON A.common = B.common INNER JOIN TableC C
ON B.common = C.common

Use cell's color as condition in if statement (function)

Although this does not directly address your question, you can actually sort your data by cell colour in Excel (which then makes it pretty easy to label all records with a particular colour in the same way and, hence, condition upon this label).

In Excel 2010, you can do this by going to Data -> Sort -> Sort On "Cell Colour".

How and when to use ‘async’ and ‘await’

This answer aims to provide some info specific to ASP.NET.

By utilizing async/await in MVC controller, it is possible to increase thread pool utilization and achieve a much better throughput, as explained in the below article,

In web applications that sees a large number of concurrent requests at start-up or has a bursty load (where concurrency increases suddenly), making these web service calls asynchronous will increase the responsiveness of your application. An asynchronous request takes the same amount of time to process as a synchronous request. For example, if a request makes a web service call that requires two seconds to complete, the request takes two seconds whether it is performed synchronously or asynchronously. However, during an asynchronous call, a thread is not blocked from responding to other requests while it waits for the first request to complete. Therefore, asynchronous requests prevent request queuing and thread pool growth when there are many concurrent requests that invoke long-running operations.

Removing elements by class name?

I prefer using forEach over for/while looping. In order to use it's necessary to convert HTMLCollection to Array first:

    .forEach(element => element.remove());

Pay attention, it's not necessary the most efficient way. Just much more elegant for me.

'Best' practice for restful POST response

Returning the whole object on an update would not seem very relevant, but I can hardly see why returning the whole object when it is created would be a bad practice in a normal use case. This would be useful at least to get the ID easily and to get the timestamps when relevant. This is actually the default behavior got when scaffolding with Rails.

I really do not see any advantage to returning only the ID and doing a GET request after, to get the data you could have got with your initial POST.

Anyway as long as your API is consistent I think that you should choose the pattern that fits your needs the best. There is not any correct way of how to build a REST API, imo.

Change width of select tag in Twitter Bootstrap

Tested alone, <select class=input-xxlarge> sets the content width of the element to 530px. (The total width of the element is slightly smaller than that of <input class=input-xxlarge> due to different padding. If this a a problem, set the paddings in your own style sheet as desired.)

So if it does not work, the effect is prevented by some setting in your own style sheet or maybe in the use other settings for the element.

In VBA get rid of the case sensitivity when comparing words?

There is a statement you can issue at the module level:

Option Compare Text

This makes all "text comparisons" case insensitive. This means the following code will show the message "this is true":

Option Compare Text

Sub testCase()
  If "UPPERcase" = "upperCASE" Then
    MsgBox "this is true: option Compare Text has been set!"
  End If
End Sub

See for example . I'm not sure it will completely solve the problem for all instances (such as the Application.Match function) but it will take care of all the if a=b statements. As for Application.Match - you may want to convert the arguments to either upper case or lower case using the LCase function.

Request failed: unacceptable content-type: text/html using AFNetworking 2.0

 UIImage *image = [UIImage imageNamed:@"decline_clicked.png"];
NSData *imageData = UIImageJPEGRepresentation(image,1);

NSString *queryStringss = [NSString stringWithFormat:@""];
queryStringss = [queryStringss stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
manager.responseSerializer.acceptableContentTypes = [NSSet setWithObject:@"text/html"];

[MBProgressHUD showHUDAddedTo:self.view animated:YES];

[manager POST:queryStringss parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData)

     [formData appendPartWithFileData:imageData name:@"fileName" fileName:@"decline_clicked.png" mimeType:@"image/jpeg"];

      success:^(AFHTTPRequestOperation *operation, id responseObject)

    NSDictionary *dict = [responseObject objectForKey:@"Result"];

    NSLog(@"Success: %@ ***** %@", operation.responseString, responseObject);
    [MBProgressHUD hideAllHUDsForView:self.view animated:YES];

      failure:^(AFHTTPRequestOperation *operation, NSError *error)
     [MBProgressHUD hideAllHUDsForView:self.view animated:YES];
     NSLog(@"Error: %@ ***** %@", operation.responseString, error);

Make function wait until element exists

A more modern approach to waiting for elements:

while(!document.querySelector(".my-selector")) {
  await new Promise(r => setTimeout(r, 500));
// now the element is loaded

Note that this code would need to be wrapped in an async function.

How to remove origin from git repository

Remove existing origin and add new origin to your project directory

>$ git remote show origin

>$ git remote rm origin

>$ git add .

>$ git commit -m "First commit"

>$ git remote add origin Copied_origin_url

>$ git remote show origin

>$ git push origin master Trust anchor for certification path not found

The reason this occur is the JVM/Dalvik haven't not confidence in the CA certificates in the system or in the user certificate stores.

To fix this with Retrofit, If you are used okhttp, with another client it's very similar.
You've to do:

A). Create a cert store contain public Key of CA. To do this you need to launch next script for *nix. You need openssl install in your machine, and download from the jar bcprov-jdk16-1.46.jar. Download this version not other, the version 1.5x is not compatible with android 4.0.4.


if [ -z $1 ]; then
  echo "Usage: cert2Android<CA cert PEM file>"
  exit 1


ALIAS=`openssl x509 -inform PEM -subject_hash -noout -in $CACERT`

if [ -f $TRUSTSTORE ]; then
    rm $TRUSTSTORE || exit 1

echo "Adding certificate to $TRUSTSTORE..."
keytool -import -v -trustcacerts -alias $ALIAS \
      -file $CACERT \
      -keystore $TRUSTSTORE -storetype BKS \
      -providerclass org.bouncycastle.jce.provider.BouncyCastleProvider \
      -providerpath $BCJAR \
      -storepass secret

echo "" 
echo "Added '$CACERT' with alias '$ALIAS' to $TRUSTSTORE..."

B). Copy the file truststore mytruststore.bks in res/raw of your project truststore location

C). Setting SSLContext of the connection:

okHttpClient = new OkHttpClient();
try {
    KeyStore ksTrust = KeyStore.getInstance("BKS");
    InputStream instream = context.getResources().openRawResource(R.raw.mytruststore);
    ksTrust.load(instream, "secret".toCharArray());

    // TrustManager decides which certificate authorities to use.
    TrustManagerFactory tmf = TrustManagerFactory
    SSLContext sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, tmf.getTrustManagers(), null);

} catch (KeyStoreException | IOException | NoSuchAlgorithmException | CertificateException | KeyManagementException e) {

How to request Administrator access inside a batch file

@echo off 
Net session >nul 2>&1 || (PowerShell start -verb runas '%~0' &exit /b)
Echo Administrative privileges have been got. & pause

The above works on my Windows 10 Version 1903

Adding a column to a dataframe in R

That is a pretty standard use case for apply():

R> vec <- 1:10
R> DF <- data.frame(start=c(1,3,5,7), end=c(2,6,7,9))
R> DF$newcol <- apply(DF,1,function(row) mean(vec[ row[1] : row[2] ] ))
  start end newcol
1     1   2    1.5
2     3   6    4.5
3     5   7    6.0
4     7   9    8.0

You can also use plyr if you prefer but here is no real need to go beyond functions from base R.

Entity Framework throws exception - Invalid object name 'dbo.BaseCs'

Instead of




even if your table name is dbo.BaseCs

How do I use the Tensorboard callback of Keras?


keras.callbacks.TensorBoard(log_dir='/Graph', histogram_freq=0,  
          write_graph=True, write_images=True)


tbCallBack = keras.callbacks.TensorBoard(log_dir='Graph', histogram_freq=0,  
          write_graph=True, write_images=True)

and set your model


Run in your terminal

tensorboard  --logdir Graph/

Calculate difference between 2 date / times in Oracle SQL

To get result in seconds:

select (END_DT - START_DT)*60*60*24 from MY_TABLE;

Check [][1]

bower automatically update bower.json

from bower help, save option has a capital S

-S, --save  Save installed packages into the project's bower.json dependencies


Mecki's answer is absolutly perfect, but it's worth adding that FreeBSD also supports SO_REUSEPORT_LB, which mimics Linux' SO_REUSEPORT behaviour - it balances the load; see setsockopt(2)

Failed Apache2 start, no error log

You have following ways to make it work:

  1. Delete /var/run/apache2/ then check if its working

  2. You can disable SELinux and then check if it works. You can disable SELinux permanantly or temporarily by using tutorial

Setting Timeout Value For .NET Web Service

After creating your client specifying the binding and endpoint address, you can assign an OperationTimeout,

client.InnerChannel.OperationTimeout = new TimeSpan(0, 5, 0);

Add floating point value to android resources/values

There is a solution:

    <item name="text_line_spacing" format="float" type="dimen">1.0</item>

In this way, your float number will be under @dimen. Notice that you can use other "format" and/or "type" modifiers, where format stands for:

Format = enclosing data type:

  • float
  • boolean
  • fraction
  • integer
  • ...

and type stands for:

Type = resource type (referenced with

  • color
  • dimen
  • string
  • style
  • etc...

To fetch resource from code, you should use this snippet:

TypedValue outValue = new TypedValue();
getResources().getValue(R.dimen.text_line_spacing, outValue, true);
float value = outValue.getFloat();  

I know that this is confusing (you'd expect call like getResources().getDimension(R.dimen.text_line_spacing)), but Android dimensions have special treatment and pure "float" number is not valid dimension.

Additionally, there is small "hack" to put float number into dimension, but be WARNED that this is really hack, and you are risking chance to lose float range and precision.

    <dimen name="text_line_spacing">2.025px</dimen>

and from code, you can get that float by

float lineSpacing = getResources().getDimension(R.dimen.text_line_spacing);

in this case, value of lineSpacing is 2.024993896484375, and not 2.025 as you would expected.

Add attribute 'checked' on click jquery

$( this ).attr( 'checked', 'checked' )

just attr( 'checked' ) will return the value of $( this )'s checked attribute. To set it, you need that second argument. Based on <input type="checkbox" checked="checked" />


Based on comments, a more appropriate manipulation would be:

$( this ).attr( 'checked', true )

And a straight javascript method, more appropriate and efficient:

this.checked = true;

Thanks @Andy E for that.

How to set size for local image using knitr for markdown?

Here's some options that keep the file self-contained without retastering the image:

Wrap the image in div tags

<div style="width:300px; height:200px">

Use a stylesheet


title: test
output: html_document
css: test.css

## Page with an image {#myImagePage}



#myImagePage img {
  width: 400px;
  height: 200px;

If you have more than one image you might need to use the nth-child pseudo-selector for this second option.

Proxy with express.js

First install express and http-proxy-middleware

npm install express http-proxy-middleware --save

Then in your server.js

const express = require('express');
const proxy = require('http-proxy-middleware');

const app = express();

// Add middleware for http proxying 
const apiProxy = proxy('/api', { target: 'http://localhost:8080' });
app.use('/api', apiProxy);

// Render your site
const renderIndex = (req, res) => {
  res.sendFile(path.resolve(__dirname, 'client/index.html'));
app.get('/*', renderIndex);

app.listen(3000, () => {
  console.log('Listening on: http://localhost:3000');

In this example we serve the site on port 3000, but when a request end with /api we redirect it to localhost:8080.

http://localhost:3000/api/login redirect to http://localhost:8080/api/login

CSS: Set Div height to 100% - Pixels

Negative margins of course!


<div id="header">
    <h1>Header Text</h1>
<div id="wrapper">
    <div id="content">
        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur 
        ullamcorper velit aliquam dolor dapibus interdum sed in dolor. Phasellus 
        vel quam et quam congue sodales.


    height: 111px;
    margin-top: 0px;
    margin-bottom: 0px;
    margin-top: -111px;
    height: 100%;
    margin-top: 111px;
    padding: 0.5em;

Why is document.write considered a "bad practice"?


  • It's the easiest way to embed inline content from an external (to your host/domain) script.
  • You can overwrite the entire content in a frame/iframe. I used to use this technique a lot for menu/navigation pieces before more modern Ajax techniques were widely available (1998-2002).


  • It serializes the rendering engine to pause until said external script is loaded, which could take much longer than an internal script.
  • It is usually used in such a way that the script is placed within the content, which is considered bad-form.

SQL Server AS statement aliased column within WHERE statement

SQL doesn't typically allow you to reference column aliases in WHERE, GROUP BY or HAVING clauses. MySQL does support referencing column aliases in the GROUP BY and HAVING, but I stress that it will cause problems when porting such queries to other databases.

When in doubt, use the actual column name:

SELECT AS latitude 
  FROM poi_table t
 WHERE < 500

I added a table alias to make it easier to see what is an actual column vs alias.


A computed column, like the one you see here:

       ( 6371*1000 * acos( cos( radians(42.3936868308) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians(-72.5277256966) ) + sin( radians(42.3936868308) ) * sin( radians( lat ) ) ) ) AS distance
  FROM poi_table 
 WHERE distance < 500;

...doesn't change that you can not reference a column alias in the WHERE clause. For that query to work, you'd have to use:

       ( 6371*1000 * acos( cos( radians(42.3936868308) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians(-72.5277256966) ) + sin( radians(42.3936868308) ) * sin( radians( lat ) ) ) ) AS distance
  FROM poi_table
 WHERE ( 6371*1000 * acos( cos( radians(42.3936868308) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians(-72.5277256966) ) + sin( radians(42.3936868308) ) * sin( radians( lat ) ) ) ) < 500;

Be aware that using a function on a column (IE: RADIANS(lat)) will render an index useless, if one exists on the column.

Highcharts - how to have a chart with dynamic height?

Alternatively, you can directly use javascript's window.onresize

As example, my code (using scriptaculos) is :

window.onresize = function (){
    var w = $("form").getWidth() + "px";
    $('gfx').setStyle( { width : w } );

Where form is an html form on my webpage and gfx the highchart graphics.

Switch to another Git tag

Clone the repository as normal:

git clone git:// RSpec.tmbundle

Then checkout the tag you want like so:

git checkout tags/1.1.4

This will checkout out the tag in a 'detached HEAD' state. In this state, "you can look around, make experimental changes and commit them, and [discard those commits] without impacting any branches by performing another checkout".

To retain any changes made, move them to a new branch:

git checkout -b 1.1.4-jspooner

You can get back to the master branch by using:

git checkout master

Note, as was mentioned in the first revision of this answer, there is another way to checkout a tag:

git checkout 1.1.4

But as was mentioned in a comment, if you have a branch by that same name, this will result in git warning you that the refname is ambiguous and checking out the branch by default:

warning: refname 'test' is ambiguous.
Switched to branch '1.1.4'

The shorthand can be safely used if the repository does not share names between branches and tags.

What is the difference between JavaScript and ECMAScript?

What is ECMAScript i.e. ES?

ECMAScript is a standard for a scripting language and the Javascript language is based on the ECMAScript standard.

Is Javascript exactly the same as ECMAScript?

  • No, Javascript is not exactly equivalent to ECMAScript.
  • The core features of Javascript are based on the ECMAScript standard, but Javascript also has other additional features that are not in the ECMA specifications/standard.

JavaScript = ECMAScript + DOM API;

DOM API like: document.getElementById('id');

Do other languages use the ECMAScript standard?

  • Yes, there are languages other than JavaScript that also implement the ECMAScript Standard as their core.
  • ActionScript (used by Adobe Flash) and JScript (used by Microsoft) are both languages that implement the ECMAScript standard.

Why is it called ECMAScript?

  • Javascript was originally created at Netscape, and they wanted to standardize the language. So, they submitted the language to the European Computer Manufacturer’s Association (ECMA) for standardization.
  • But, there were trademark issues with the name Javascript, and the standard became called ECMAScript, which is the name it holds today as well.
  • Because of trademark issues, Microsoft’s version of the language is called JScript – even though JScript is, at its core, the same language as Javascript.

jQuery get an element by its data-id


How to plot a histogram using Matplotlib in Python with a list of data?

If you want a histogram, you don't need to attach any 'names' to x-values, as on x-axis you would have data bins:

import matplotlib.pyplot as plt
import numpy as np
%matplotlib inline

x = np.random.normal(size=1000)

plt.hist(x, density=True, bins=30)  # density=False would make counts

enter image description here

Note, the number of bins=30 was chosen arbitrarily, and there is Freedman–Diaconis rule to be more scientific in choosing the "right" bin width:

![enter image description here , where IQR is Interquartile range and n is total number of datapoints to plot

So, according to this rule one may calculate number of bins as:

q25, q75 = np.percentile(x,[.25,.75])
bin_width = 2*(q75 - q25)*len(x)**(-1/3)
bins = round((x.max() - x.min())/bin_width)
print("Freedman–Diaconis number of bins:", bins)
plt.hist(x, bins = bins);

Freedman–Diaconis number of bins: 82

enter image description here

And finally you can make your histogram a bit fancier with PDF line, titles, and legend:

import scipy.stats as st

plt.hist(x, density=True, bins=82, label="Data")
mn, mx = plt.xlim()
plt.xlim(mn, mx)
kde_xs = np.linspace(mn, mx, 300)
kde = st.gaussian_kde(x)
plt.plot(kde_xs, kde.pdf(kde_xs), label="PDF")
plt.legend(loc="upper left")

enter image description here

However, if you have limited number of data points, like in OP, a bar plot would make more sense to represent your data. Then you may attach labels to x-axis:

x = np.arange(3), height=[1,2,3])
plt.xticks(x, ['a','b','c'])

enter image description here

How to make tesseract to recognize only numbers, when they are mixed with letters?

I made it a bit different (with tess-two). Maybe it will be useful for somebody.

So you need to initialize first the API.

TessBaseAPI baseApi = new TessBaseAPI();
baseApi.init(datapath, language, ocrEngineMode);

Then set the following variables

baseApi.setVariable(TessBaseAPI.VAR_CHAR_BLACKLIST, "!?@#$%&*()<>_-+=/:;'\"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
baseApi.setVariable(TessBaseAPI.VAR_CHAR_WHITELIST, ".,0123456789");
baseApi.setVariable("classify_bln_numeric_mode", "1");

In this way the engine will check only the numbers.

Meaning of *& and **& in C++

*& signifies the receiving the pointer by reference. It means it is an alias for the passing parameter. So, it affects the passing parameter.

#include <iostream>
using namespace std;

void foo(int *ptr)
    ptr = new int(50);    // Modifying the pointer to point to a different location
    cout << "In foo:\t" << *ptr << "\n"; 
    delete ptr ;

void bar(int *& ptr)
    ptr = new int(80);    // Modifying the pointer to point to a different location
    cout << "In bar:\t" << *ptr << "\n"; 
    // Deleting the pointer will result the actual passed parameter dangling
int main()
    int temp = 100 ;
    int *p = &temp ;

    cout << "Before foo:\t" << *p << "\n";
    foo(p) ;
    cout << "After foo:\t" << *p << "\n";

    cout << "Before bar:\t" << *p << "\n";
    bar(p) ;
    cout << "After bar:\t" << *p << "\n";

    delete p;

    return 0;


Before foo: 100
In foo: 50
After foo:  100
Before bar: 100
In bar: 80
After bar:  80

Get user location by IP address

You need an IP-address-based reverse geocoding API... like the one from I'm sure there are plenty of options available.

You may want to allow the user to override this, however. For example, they could be on a corporate VPN which makes the IP address look like it's in a different country.

How to redirect output of an already running process

You can also do it using reredirect (

The command bellow redirects the outputs (standard and error) of the process PID to FILE:

reredirect -m FILE PID

The README of reredirect also explains other interesting features: how to restore the original state of the process, how to redirect to another command or to redirect only stdout or stderr.

The tool also provides relink, a script allowing to redirect the outputs to the current terminal:

relink PID
relink PID | grep usefull_content

(reredirect seems to have same features than Dupx described in another answer but, it does not depend on Gdb).

Failing to run jar file from command line: “no main manifest attribute”

First run your application from eclipse to create launch configuration. Then just follow the steps:

  1. From the menu bar's File menu, select Export.
  2. Expand the Java node and select Runnable JAR file. Click Next.
  3. In the Runnable JAR File Specification page, select a 'Java Application' launch configuration to use to create a runnable JAR.
  4. In the Export destination field, either type or click Browse to select a location for the JAR file.
  5. Select an appropriate library handling strategy.
  6. Optionally, you can also create an ANT script to quickly regenerate a previously created runnable JAR file.

Source: Creating a New Runnable JAR File at

Appending a line break to an output file in a shell script

You can do that without an I/O redirection:

sed -i 's/$/\n/' filename

You can also use this command to append a newline to a list of files:

find dir -name filepattern | xargs sed -i 's/$/\n/' filename

For echo, some shells implement it as a shell builtin command. It might not accept the -e option. If you still want to use echo, try to find where the echo binary file is, using which echo. In most cases, it is located in /bin/echo, so you can use /bin/echo -e "\n" to echo a new line.

How to access a value defined in the file in Spring Boot

to pick the values from property file, we can have a Config reader class something like ApplicationConfigReader.class Then define all the variables against properties. Refer below example,

myapp.nationality: INDIAN
myapp.gender: Male

Below is corresponding reader class.

@ConfigurationProperties(prefix = "myapp") 
class AppConfigReader{
    private String nationality;
    private String gender

    //getter & setter

Now we can auto-wire the reader class wherever we want to access property values. e.g.

class ServiceImpl{
    private AppConfigReader appConfigReader;

    //fetching values from config reader
    String nationality = appConfigReader.getNationality() ; 
    String gender = appConfigReader.getGender(); 

When should I use a struct rather than a class in C#?

Following are the rules defined at Microsoft website:

?? CONSIDER defining a struct instead of a class if instances of the type are small and commonly short-lived or are commonly embedded in other objects.

? AVOID defining a struct unless the type has all of the following characteristics:

It logically represents a single value, similar to primitive types (int, double, etc.).

It has an instance size under 16 bytes.

It is immutable.

It will not have to be boxed frequently.

for further reading

Save a list to a .txt file

Try this, if it helps you

values = ['1', '2', '3']

with open("file.txt", "w") as output:

How does Java import work?

The classes which you are importing have to be on the classpath. So either the users of your Applet have to have the libraries in the right place or you simply provide those libraries by including them in your jar file. For example like this: Easiest way to merge a release into one JAR file

How to log SQL statements in Spring Boot?

This works for me (YAML):

        show_sql: true
        format_sql: true
        type: trace

add Shadow on UIView using swift 3

Although the accepted answer is great and it works as it should, I've modified it to split offSet: CGSize to offsetX: CGFloat and offsetY: CGFloat.

extension UIView {
  func dropShadow(offsetX: CGFloat, offsetY: CGFloat, color: UIColor, opacity: Float, radius: CGFloat, scale: Bool = true) {
    layer.masksToBounds = false
    layer.shadowOffset = CGSize(width: offsetX, height: offsetY)
    layer.shadowColor = color.cgColor
    layer.shadowOpacity = opacity
    layer.shadowRadius = radius
    layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
    layer.shouldRasterize = true
    layer.rasterizationScale = scale ? UIScreen.main.scale : 1

Class not registered Error

Somewhere in the code you are using, there is a call to the Win32 API, CoCreateInstance, to dynamically load a DLL and instantiate an object from it.

The mapping between the component ID and the DLL that is capable of instantiating that object is usually found in HEKY_CLASSES_ROOT\CLSID in the registry. To discuss this further would be to explain a lot about COM in Windows. But the error indicates that the COM guid is not present in the registry.

I don't much about what the PackAndGo DLL is (an Autodesk component), but I suspect you simply need to "install" that component or the software package it came with through the designated installer to have that DLL and appropriate COM registry keys on your computer you are trying to run your code on. (i.e. go run setup.exe for this product).

In other words, I think you need to install "Pack and Go" on this computer instead of just copying the DLL to the target machine.

Also, make sure you decide to build your code appropriate as 32-bit vs. 64-bit depending on the which build flavor (32 or 64 bit) of Pack And Go you install.

Android - styling seek bar

I wanted to create a style for the seekbar and then add the style to a theme so that I could have it applied to an entire theme while still allowing a substyle to override it. Here is what I did:

<!-- Blue App Theme -->
    <style name="AppTheme.Blue" parent="BaseTheme.Blue">        
        <item name="android:seekBarStyle">@style/SeekbarStyle.Blue</item>
        <item name="seekBarStyle">@style/SeekbarStyle.Blue</item> <!--This is essential for some devices, e.g. Samsung-->

<!-- Slider Styles -->
<style name="SeekbarStyle.Blue" parent="Widget.AppCompat.SeekBar">
        <item name="android:progressBackgroundTint">@color/material_blue_a700_pct_30</item>
        <item name="android:thumbTint">@color/material_blue_a700</item>
        <item name="android:thumbTintMode">src_in</item>
        <item name="android:progressTint">@color/material_blue_a700</item>

<style name="SeekbarStyle.Green" parent="Widget.AppCompat.SeekBar">
        <item name="android:progressBackgroundTint">@color/material_green_a700_pct_30</item>
        <item name="android:thumbTint">@color/material_green_a700</item>
        <item name="android:thumbTintMode">src_in</item>
        <item name="android:progressTint">@color/material_green_a700</item>

The above sets the Theme seekbar style to blue for all devices 21+ including Samsung (which need the seekBarStyle applied in addition to android:seekBarStyle; not sure why but I saw this issue firsthand). If you want all seekbars to keep the theme style and only apply the green seekbar style to a few widgets then add the following to the widget you want:


How to set the color of "placeholder" text?

For Firefox use:

 input:-moz-placeholder { color: #aaa; }
 textarea:-moz-placeholder { color: #aaa;}

For all other browsers (Chrome, IE, Safari), just use:

 .placeholder { color: #aaa; }

Postgres where clause compare timestamp

Assuming you actually mean timestamp because there is no datetime in Postgres

Cast the timestamp column to a date, that will remove the time part:

select *
from the_table
where the_timestamp_column::date = date '2015-07-15';

This will return all rows from July, 15th.

Note that the above will not use an index on the_timestamp_column. If performance is critical, you need to either create an index on that expression or use a range condition:

select *
from the_table
where the_timestamp_column >= timestamp '2015-07-15 00:00:00'
  and the_timestamp_column < timestamp '2015-07-16 00:00:00';

When to use self over $this?

self (not $self) refers to the type of class, where as $this refers to the current instance of the class. self is for use in static member functions to allow you to access static member variables. $this is used in non-static member functions, and is a reference to the instance of the class on which the member function was called.

Because this is an object, you use it like: $this->member

Because self is not an object, it's basically a type that automatically refers to the current class, you use it like: self::member

Converting from a string to boolean in Python?

Yet another option

from ansible.module_utils.parsing.convert_bool import boolean
# False
# True
# True

How to change options of <select> with jQuery?

Removing and adding DOM element is slower than modification of existing one.

If your option sets have same length, you may do something like this:

$('#my-select option')
.each(function(index) {

In case your new option set has different length, you may delete/add empty options you really need, using some technique described above.

No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here

I was getting the same the error inside a shared function, but it was only happening for some calls to this shared function. I eventually realized that one of classes calling the shared function wasn't wrapping it inside of a Unit of Work. Once I updated this classes functions with a Unit of Work everything worked as expected.

So just posting this for any future visitors who run into this same error, but for whom the accepted answer doesn't apply.

Incrementing a date in JavaScript

Tomorrow in one line in pure JS but it's ugly !

new Date(new Date().setDate(new Date().getDate() + 1))

Here is the result :

Thu Oct 12 2017 08:53:30 GMT+0200 (Romance Summer Time)

Return value in a Bash function

$(...) captures the text sent to stdout by the command contained within. return does not output to stdout. $? contains the result code of the last command.

fun1 (){
  return 34

fun2 (){
  local res=$?
  echo $res

Converting string from snake_case to CamelCase in Ruby

If you use Rails, Use classify. It handles edge cases well.

"app_user".classify # => AppUser
"user_links".classify   # => UserLink


This answer is specific to the description given in the question(it is not specific to the question title). If one is trying to convert a string to camel-case they should use Sergio's answer. The questioner states that he wants to convert app_user to AppUser (not App_user), hence this answer..

Inserting a PDF file in LaTeX

I don't think there would be an automatic way. You might also want to add a page number to the appendix correctly. Assuming that you already have your pdf document of several pages, you'll have to extract each page first of your pdf document using Adobe Acrobat Professional for instance and save each of them as a separate pdf file. Then you'll have to include each of the the pdf documents as images on an each page basis (1 each page) and use newpage between each page e,g,

\section{Quiz 1}\label{sec:Quiz}
\begin{figure}[htp] \centering{
\caption{Experiment 1}

\section{Sample paper}\label{sec:Sample}
\begin{figure}[htp] \centering{
\caption{Experiment 2}

Now each page will appear with 1 pdf image per page and you'll have a correct page number at the bottom. As shown in my example, you'll have to play a bit with the scale factor for each image to get it in the right size that will fit on a single page. Hope that helps...

How to read pickle file?

There is a read_pickle function as part of pandas 0.22+

import pandas as pd

object = pd.read_pickle(r'filepath')

Concatenating strings in C, which method is more efficient?

size_t lf = strlen(first);
size_t ls = strlen(second);

char *both = (char*) malloc((lf + ls + 2) * sizeof(char));

strcpy(both, first);

both[lf] = ' ';
strcpy(&both[lf+1], second);

How to copy a file to another path?

This is what I did to move a test file from the downloads to the desktop. I hope its useful.

private void button1_Click(object sender, EventArgs e)//Copy files to the desktop
        string sourcePath = @"C:\Users\UsreName\Downloads";
        string targetPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
        string[] shortcuts = {

            listbox1.Items.Add("Starting: Copy shortcuts to dektop.");
            for (int i = 0; i < shortcuts.Length; i++)
                if (shortcuts[i]!= null)
                    File.Copy(Path.Combine(sourcePath, shortcuts[i]), Path.Combine(targetPath, shortcuts[i]), true);                        
                    listbox1.Items.Add(shortcuts[i] + " was moved to desktop!");
                    listbox1.Items.Add("Shortcut " + shortcuts[i] + " Not found!");
        catch (Exception ex)
            listbox1.Items.Add("Unable to Copy file. Error : " + ex);

What is the equivalent to getLastInsertId() in Cakephp?

I think it works with getLastInsertId() if you use InnoDB Tables in your MySQL Database. You also can use $this->Model->id

What is the difference between class and instance methods?


A class method typically either creates a new instance of the class or retrieves some global properties of the class. Class methods do not operate on an instance or have any access to instance variable.


An instance method operates on a particular instance of the class. For example, the accessors method that you implemented are all instance methods. You use them to set or get the instance variables of a particular object.


To invoke an instance method, you send the message to an instance of the class.

To invoke a class method, you send the message to the class directly.

Source: IOS - Objective-C - Class Methods And Instance Methods

Pass a PHP array to a JavaScript function


In the following example $php_variable can be any PHP variable.

<script type="text/javascript">
    var obj = <?php echo json_encode($php_variable); ?>;

In your code, you could use like the following:

drawChart(600/50, <?php echo json_encode($day); ?>, ...)

In cases where you need to parse out an object from JSON-string (like in an AJAX request), the safe way is to use JSON.parse(..) like the below:

var s = "<JSON-String>";
var obj = JSON.parse(s);

jQuery Ajax error handling, show custom exception messages

This is what I did and it works so far in a MVC 5 application.

Controller's return type is ContentResult.

public ContentResult DoSomething()
        Response.StatusCode = 500 //Anything other than 2XX HTTP status codes should work
        Response.Write("My Message");
        return new ContentResult();

    //Do something in here//
    string json = "whatever json goes here";

    return new ContentResult{Content = json, ContentType = "application/json"};

And on client side this is what ajax function looks like

    type: "POST",
    url: URL,
    data: DATA,
    dataType: "json",
    success: function (json) {
        //Do something with the returned json object.
    error: function (xhr, status, errorThrown) {
        //Here the status code can be retrieved like;

        //The message added to Response object in Controller can be retrieved as following.

How to validate phone numbers using regex

Here is what I use

function isValidTel ($tel) {
    preg_match('/^[\+]?[(]?[0-9]{3}[)]?[-\s\.]?[0-9]{3}[-\s\.]?[0-9]{4,6}$/im', $tel, $matches);
    return !! $matches;

Check it out in this regex tester

How to connect to MongoDB in Windows?

If you are getting these type of errors when running mongod from command line or running mongodb server, enter image description here
then follow these steps,

  1. Create db and log directories in C: drive
    C:/data/db and C:data/log
  2. Create an empty log file in log dir named mongo.log
  3. Run mongod from command line to run the mongodb server or create a batch file on desktop which can run the mongod.exe file from your mongodb installation direction. That way you just have to click the batch file from your desktop and mongodb will start.
  4. If you have 32-bit system, try using --journal with mongod command.

How to "git clone" including submodules?

Submodules parallel fetch aims at reducing the time required to fetch a repositories and all of its related submodules by enabling the fetching of multiple repositories at once. This can be accomplished by using the new --jobs option, e.g.:

git fetch --recurse-submodules --jobs=4

According to Git team, this can substantially speed up updating repositories that contain many submodules. When using --recurse-submodules without the new --jobs option, Git will fetch submodules one by one.


Uploading both data and files in one form using Ajax?

<form id="form" method="post" action="otherpage.php" enctype="multipart/form-data">
    <input type="text" name="first" value="Bob" />
    <input type="text" name="middle" value="James" />
    <input type="text" name="last" value="Smith" />
    <input name="image" type="file" />
    <button type='button' id='submit_btn'>Submit</button>

$(document).on("click", "#submit_btn", function (e) {
    //Prevent Instant Click  
    // Create an FormData object 
    var formData = $("#form").submit(function (e) {
    //formData[0] contain form data only 
    // You can directly make object via using form id but it require all ajax operation inside $("form").submit(<!-- Ajax Here   -->)
    var formData = new FormData(formData[0]);
        url: $('#form').attr('action'),
        type: 'POST',
        data: formData,
        success: function (response) {
        contentType: false,
        processData: false,
        cache: false
    return false;

///// otherpage.php


Deleting multiple elements from a list

An alternative list comprehension method that uses list index values:

stuff = ['a', 'b', 'c', 'd', 'e', 'f', 'woof']
index = [0, 3, 6]
new = [i for i in stuff if stuff.index(i) not in index]

This returns:

['b', 'c', 'e', 'f']

getting the table row values with jquery

Give something like this a try:

    $("#thisTable tr").click(function(){

Here is a fiddle of the code in action:

node.js http 'get' request with query string parameters

If you don't want use external package , Just add the following function in your utilities :

var params=function(req){
  let q=req.url.split('?'),result={};
           try {
           } catch (e) {
  return result;

Then , in createServer call back , add attribute params to request object :

     req.params=params(req); // call the function above ;
       * http://mysite/add?name=Ahmed
     console.log( ; // display : "Ahmed"


java.lang.IllegalArgumentException: No converter found for return value of type

In my case, I was returning Boolean in Response Entity and had :

produces = MediaType.TEXT_PLAIN_VALUE,

When i changed it to below


It worked!

Example of what i had.

@PostMapping(value = "/xxx-xxxx",
            produces = MediaType.APPLICATION_JSON_VALUE,
            consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Boolean> yyyy(

Socket.IO - how do I get a list of connected sockets/clients? 1.4

Object.keys(io.sockets.sockets); gives you all the connected sockets. 1.0 As of 1.0, the actual accepted answer isn't valid anymore. So I made a small function that I use as a temporary fix :

function findClientsSocket(roomId, namespace) {
    var res = []
    // the default namespace is "/"
    , ns = io.of(namespace ||"/");

    if (ns) {
        for (var id in ns.connected) {
            if(roomId) {
                var index = ns.connected[id].rooms.indexOf(roomId);
                if(index !== -1) {
            } else {
    return res;

Api for No namespace becomes

// var clients = io.sockets.clients();
// becomes : 
var clients = findClientsSocket();

// var clients = io.sockets.clients('room');
// all users from room `room`
// becomes
var clients = findClientsSocket('room');

Api for a namespace becomes :

// var clients = io.of('/chat').clients();
// becomes
var clients = findClientsSocket(null, '/chat');

// var clients = io.of('/chat').clients('room');
// all users from room `room`
// becomes
var clients = findClientsSocket('room', '/chat');

Also see this related question, in which I give a function that returns the sockets for a given room.

function findClientsSocketByRoomId(roomId) {
var res = []
, room = io.sockets.adapter.rooms[roomId];
if (room) {
    for (var id in room) {
return res;
} 0.7

API for no namespace:

var clients = io.sockets.clients();
var clients = io.sockets.clients('room'); // all users from room `room`

For a namespace

var clients = io.of('/chat').clients();
var clients = io.of('/chat').clients('room'); // all users from room `room`

Note: Since it seems the API is prone to breaking, and some solution rely on implementation details, it could be a matter of tracking the clients yourself:

var clients = [];

io.sockets.on('connect', function(client) {

    client.on('disconnect', function() {
        clients.splice(clients.indexOf(client), 1);

How to get rows count of internal table in abap?

if I understand your question correctly, you want to know the row number during a conditional loop over an internal table. You can use the system variable sy-tabix if you work with internal tables. Please refer to the ABAP documentation if you need more information (especially the chapter on internal table processing).


LOOP AT itab INTO workarea
        WHERE tablefield = value.

     WRITE: 'This is row number ', sy-tabix.


How to get Real IP from Visitor?

This is my function.

benefits :

  • Work if $_SERVER was not available.
  • Filter private and/or reserved IPs;
  • Process all forwarded IPs in X_FORWARDED_FOR
  • Compatible with CloudFlare
  • Can set a default if no valid IP found!
  • Short & Simple !

 * Get real user ip
 * Usage sample:
 * GetRealUserIp();
 * @param string $default default return value if no valid ip found
 * @param int    $filter_options filter options. default is FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE
 * @return string real user ip

function GetRealUserIp($default = NULL, $filter_options = 12582912) {

    foreach ($all_ips as $ip) {
        if ($ip = filter_var($ip, FILTER_VALIDATE_IP, $filter_options))
    return $ip?$ip:$default;

Truststore and Keystore Definitions

You may also be interested in the write-up from Sun, as part of the standard JSSE documentation:

Typically, the trust store is used to store only public keys, for verification purposes, such as with X.509 authentication. For manageability purposes, it's quite common for admins or developers to simply conflate the two into a single store.

SQL SERVER, SELECT statement with auto generate row id

Select (Select count(y.au_lname) from dbo.authors y
where y.au_lname + y.au_fname <= x.au_lname + y.au_fname) as Counterid,
x.au_lname,x.au_fname from authors x group by au_lname,au_fname
order by Counterid --Alternatively that can be done which is equivalent as above..

How to loop through Excel files and load them into a database using SSIS package?

I ran into an article that illustrates a method where the data from the same excel sheet can be imported in the selected table until there is no modifications in excel with data types.

If the data is inserted or overwritten with new ones, importing process will be successfully accomplished, and the data will be added to the table in SQL database.

The article may be found here:

Hope it helps.