Programs & Examples On #Orders

How to get WooCommerce order details

Accessing direct properties and related are explained

// Get an instance of the WC_Order object
            $order = wc_get_order($order_id);
            $order_data = array(
                    'order_id' => $order->get_id(),
                    'order_number' => $order->get_order_number(),
                    'order_date' => date('Y-m-d H:i:s', strtotime(get_post($order->get_id())->post_date)),
                    'status' => $order->get_status(),
                    'shipping_total' => $order->get_total_shipping(),
                    'shipping_tax_total' => wc_format_decimal($order->get_shipping_tax(), 2),
                    'fee_total' => wc_format_decimal($fee_total, 2),
                    'fee_tax_total' => wc_format_decimal($fee_tax_total, 2),
                    'tax_total' => wc_format_decimal($order->get_total_tax(), 2),
                    'cart_discount' => (defined('WC_VERSION') && (WC_VERSION >= 2.3)) ? wc_format_decimal($order->get_total_discount(), 2) : wc_format_decimal($order->get_cart_discount(), 2),
                    'order_discount' => (defined('WC_VERSION') && (WC_VERSION >= 2.3)) ? wc_format_decimal($order->get_total_discount(), 2) : wc_format_decimal($order->get_order_discount(), 2),
                    'discount_total' => wc_format_decimal($order->get_total_discount(), 2),
                    'order_total' => wc_format_decimal($order->get_total(), 2),
                    'order_currency' => $order->get_currency(),
                    'payment_method' => $order->get_payment_method(),
                    'shipping_method' => $order->get_shipping_method(),
                    'customer_id' => $order->get_user_id(),
                    'customer_user' => $order->get_user_id(),
                    'customer_email' => ($a = get_userdata($order->get_user_id() )) ? $a->user_email : '',
                    'billing_first_name' => $order->get_billing_first_name(),
                    'billing_last_name' => $order->get_billing_last_name(),
                    'billing_company' => $order->get_billing_company(),
                    'billing_email' => $order->get_billing_email(),
                    'billing_phone' => $order->get_billing_phone(),
                    'billing_address_1' => $order->get_billing_address_1(),
                    'billing_address_2' => $order->get_billing_address_2(),
                    'billing_postcode' => $order->get_billing_postcode(),
                    'billing_city' => $order->get_billing_city(),
                    'billing_state' => $order->get_billing_state(),
                    'billing_country' => $order->get_billing_country(),
                    'shipping_first_name' => $order->get_shipping_first_name(),
                    'shipping_last_name' => $order->get_shipping_last_name(),
                    'shipping_company' => $order->get_shipping_company(),
                    'shipping_address_1' => $order->get_shipping_address_1(),
                    'shipping_address_2' => $order->get_shipping_address_2(),
                    'shipping_postcode' => $order->get_shipping_postcode(),
                    'shipping_city' => $order->get_shipping_city(),
                    'shipping_state' => $order->get_shipping_state(),
                    'shipping_country' => $order->get_shipping_country(),
                    'customer_note' => $order->get_customer_note(),
                    'download_permissions' => $order->is_download_permitted() ? $order->is_download_permitted() : 0,

Additional details

  $line_items_shipping = $order->get_items('shipping');
            foreach ($line_items_shipping as $item_id => $item) {
                if (is_object($item)) {
                    if ($meta_data = $item->get_formatted_meta_data('')) :
                        foreach ($meta_data as $meta_id => $meta) :
                            if (in_array($meta->key, $line_items_shipping)) {
                            // html entity decode is not working preoperly
                            $shipping_items[] = implode('|', array('item:' . wp_kses_post($meta->display_key), 'value:' . str_replace('×', 'X', strip_tags($meta->display_value))));

            //get fee and total
            $fee_total = 0;
            $fee_tax_total = 0;

            foreach ($order->get_fees() as $fee_id => $fee) {

                $fee_items[] = implode('|', array(
                        'name:' .  html_entity_decode($fee['name'], ENT_NOQUOTES, 'UTF-8'),
                        'total:' . wc_format_decimal($fee['line_total'], 2),
                        'tax:' . wc_format_decimal($fee['line_tax'], 2),

                $fee_total += $fee['line_total'];
                $fee_tax_total += $fee['line_tax'];

            // get tax items
            foreach ($order->get_tax_totals() as $tax_code => $tax) {            
                $tax_items[] = implode('|', array(
                    'code:' . $tax_code,
                    'total:' . wc_format_decimal($tax->amount, 2),

            // add coupons
            foreach ($order->get_items('coupon') as $_ => $coupon_item) {

                $coupon = new WC_Coupon($coupon_item['name']);

                $coupon_post = get_post((WC()->version < '2.7.0') ? $coupon->id : $coupon->get_id());
                $discount_amount = !empty($coupon_item['discount_amount']) ? $coupon_item['discount_amount'] : 0;
                $coupon_items[] = implode('|', array(
                        'code:' . $coupon_item['name'],
                        'description:' . ( is_object($coupon_post) ? $coupon_post->post_excerpt : '' ),
                        'amount:' . wc_format_decimal($discount_amount, 2),

            foreach ($order->get_refunds() as $refunded_items){
                $refund_items[] = implode('|', array(
                    'amount:' . $refunded_items->get_amount(),
            'reason:' . $refunded_items->get_reason(),
                    'date:'. date('Y-m-d H-i-s',strtotime((WC()->version < '2.7.0') ? $refunded_items->date_created : $refunded_items->get_date_created())),

Read/Parse text file line by line in VBA

You Can use this code to read line by line in text file and You could also check about the first character is "*" then you can leave that..

Public Sub Test()

    Dim ReadData as String

    Open "C:\satheesh\myfile\file.txt" For Input As #1

    Do Until EOF(1) 
       Line Input #1, ReadData 'Adding Line to read the whole line, not only first 128 positions
    If Not Left(ReadData, 1) = "*" then
       '' you can write the variable ReadData into the database or file
    End If 


    Close #1

End Sub

GIT commit as different user without email / or only email


A U Thor <[email protected]>

simply mean that you should specify

FirstName MiddleName LastName <[email protected]>

Looks like middle and last names are optional (maybe the part before email doesn't have a strict format at all). Try, for example, this:

git commit --author="John <[email protected]>" -m "some fix"

As the docs say:

       Override the commit author. Specify an explicit author using the standard 
       A U Thor <[email protected]> format. Otherwise <author> is assumed to 
       be a pattern and is used to search for an existing commit by that author 
       (i.e. rev-list --all -i --author=<author>); the commit author is then copied 
       from the first such commit found.

if you don't use this format, git treats provided string as a pattern and tries to find matching name among the authors of other commits.

How to empty the message in a text area with jquery?

A comment to jarijira

Well I have had many issues with .html and .empty() methods for inputs o. If the id represents an input and not another type of html selector like

or use the .val() function to manipulate.

For example: this is the proper way to manipulate input values

<textarea class="form-control" id="someInput"></textarea>

$(document).ready(function () {
     var newVal='test'
     $('#someInput').val('') //clear input value
     $('#someInput').val(newVal) //override w/ the new value
     newVal= $('#someInput').val(newVal) //get input value


For improper, but sometimes works For example: this is the proper way to manipulate input values

<textarea class="form-control" id="someInput"></textarea>

$(document).ready(function () {
     var newVal='test'
     $('#someInput').html('') //clear input value
     $('#someInput').empty() //clear html inside of the id
     $('#someInput').html(newVal) //override the html inside of text area w/ string could be '<div>test3</div>
     really overriding with a string manipulates the value, but this is not the best practice as you do not put things besides strings or values inside of an input. 
     newVal= $('#someInput').val(newVal) //get input value


An issue that I had was I was using the $getJson method and I was indeed able to use .html calls to manipulate my inputs. However, whenever I had an error or fail on the getJSON I could no longer change my inputs using the .clear and .html calls. I could still return the .val(). After some experimentation and research I discovered that you should only use the .val() function to make changes to input fields.

Xcode warning: "Multiple build commands for output file"

Commenting use_frameworks! in PodFile worked for me.


Note: Did this on XCode 10.1, pod version 1.8.4

An efficient way to transpose a file in Bash

Another bash variant

$ cat file 
XXXX    col1    col2    col3
row1    0       1       2
row2    3       4       5
row3    6       7       8
row4    9       10      11



while read line; do
    for item in $line; { printf -v A$I[$i] $item; ((i++)); }
done < file
indexes=$(seq 0 $i)

for i in $indexes; {
    while ((J<I)); do
        printf "${!arr}\t"


$ ./test 
XXXX    row1    row2    row3    row4    
col1    0       3       6       9   
col2    1       4       7       10  
col3    2       5       8       11

How to edit default dark theme for Visual Studio Code?

The file you are looking for is at,

Microsoft VS Code\resources\app\extensions\theme-defaults\themes

on Windows and search for filename dark_vs.json to locate it on any other system.


With new versions of VSCode you don't need to hunt for the settings file to customize the theme. Now you can customize your color theme with the workbench.colorCustomizations and editor.tokenColorCustomizations user settings. Documentation on the matter can be found here.

How do I get the localhost name in PowerShell?

You can just use the .NET Framework method:




How to have git log show filenames like svn log -v

git diff --stat HEAD^! shows changed files and added/removed line counts for the last commit (HEAD).

It seems to me that there is no single command to get concise output consisting only of filenames and added and removed line counts for several commits at once, so I created my own bash script for that:

for ((i=0; i<=$1; i++))
    sha1=`git log -1 --skip=$i --pretty=format:%H`
    echo "HEAD~$i $sha1"
    git diff --stat HEAD~$(($i+1)) HEAD~$i 

To be called eg. ./changed_files 99 to get the changes in a concise form from HEAD to HEAD~99. Can be piped eg. to less.

Undefined symbols for architecture armv7

If you have the flag -ObjC under your Target > Build Settings > Other Linker Flags and you're getting this issue, consider removing it. If you intentionally added it because you need to load some Obj-C code from a static library that wouldn't normally be loaded otherwise, IE, an Obj-C category, then you should use -force_load <path> instead of -ObjC.

<path> should be relative to your Xcode project directory. IE, if your directory structure looks like this:

  + iOSAPI.framework
      + iOSAPI
  + iOSAPI.xcodeproj

Then you should have this flag set for Other Linker Flags:

-force_load iOSAPI.framework/iOSAPI

If you want to include multiple libraries like that, then you should include a separate -force_load line for each of them.

-force_load iOSAPI.framework/iOSAPI
-force_load another.framework/another

Generate fixed length Strings filled with whitespaces

import org.apache.commons.lang3.StringUtils;

String stringToPad = "10";
int maxPadLength = 10;
String paddingCharacter = " ";

StringUtils.leftPad(stringToPad, maxPadLength, paddingCharacter)

Way better than Guava imo. Never seen a single enterprise Java project that uses Guava but Apache String Utils is incredibly common.

IntelliJ IDEA shows errors when using Spring's @Autowired annotation

director:Settings - Editor - Inspections - Spring - Spring Core - Code - Autowiring for Bean Class 
operate:checkout ???
1.impl class add @service
like this:
public class CityServiceImpl implements CityService{
private CityDao cityDao;

like this
2.dao file class add @Repository
public interface CityDao {

Select single item from a list

Use the FirstOrDefault selector.

var list = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

var firstEven = list.FirstOrDefault(n => n % 2 == 0);

if (firstEven == 0)
    Console.WriteLine("no even number");
    Console.WriteLine("first even number is {0}", firstEven);

Just pass in a predicate to the First or FirstOrDefault method and it'll happily go round' the list and picks the first match for you.

If there isn't a match, FirstOrDefault will returns the default value of whatever datatype the list items is.

Hope this helps :-)

How to edit incorrect commit message in Mercurial?

In TortoiseHg, right-click on the revision you want to modify. Choose Modify History->Import MQ. That will convert all the revisions up to and including the selected revision from Mercurial changesets into Mercurial Queue patches. Select the Patch you want to modify the message for, and it should automatically change the screen to the MQ editor. Edit the message which is in the middle of the screen, then click QRefresh. Finally, right click on the patch and choose Modify History->Finish Patch, which will convert it from a patch back into a change set.

Oh, this assumes that MQ is an active extension for TortoiseHG on this repository. If not, you should be able to click File->Settings, click Extensions, and click the mq checkbox. It should warn you that you have to close TortoiseHg before the extension is active, so close and reopen.

What __init__ and self do in Python?

In short:

  1. self as it suggests, refers to itself- the object which has called the method. That is, if you have N objects calling the method, then self.a will refer to a separate instance of the variable for each of the N objects. Imagine N copies of the variable a for each object
  2. __init__ is what is called as a constructor in other OOP languages such as C++/Java. The basic idea is that it is a special method which is automatically called when an object of that Class is created

How can I send the "&" (ampersand) character via AJAX?

You might want to use encodeURIComponent().

encodeURIComponent("&quot;Busola&quot;"); // => %26quot%3BBusola%26quot%3B

Printing with sed or awk a line following a matching pattern

It's the line after that match that you're interesting in, right? In sed, that could be accomplished like so:

sed -n '/ABC/{n;p}' infile

Alternatively, grep's A option might be what you're looking for.

-A NUM, Print NUM lines of trailing context after matching lines.

For example, given the following input file:


You could use the following:

$ grep -A 1 "bar" file
$ sed -n '/bar/{n;p}' file

Hope that helps.

An error occurred while collecting items to be installed (Access is denied)

I just solved this problem by unchecking Read only checkbox of the Program Files/eclipse folder on win7.

Apply to all files and folders.

HTML Button : Navigate to Other Page - Different Approaches

I use method 3 because it's the most understandable for others (whenever you see an <a> tag, you know it's a link) and when you are part of a team, you have to make simple things ;).

And finally I don't think it's useful and efficient to use JS simply to navigate to an other page.

Creating and playing a sound in swift

This code works for me. Use Try and Catch for AVAudioPlayer

import UIKit
import AVFoundation
class ViewController: UIViewController {

    //Make sure that sound file is present in your Project.
    var CatSound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("Meow-sounds.mp3", ofType: "mp3")!)
    var audioPlayer = AVAudioPlayer()

    override func viewDidLoad() {

        do {

            audioPlayer = try AVAudioPlayer(contentsOfURL: CatSound)

        } catch {

            print("Problem in getting File")

        // Do any additional setup after loading the view, typically from a nib.

    override func didReceiveMemoryWarning() {
        // Dispose of any resources that can be recreated.

    @IBAction func button1Action(sender: AnyObject) {

Creating a select box with a search option

This will work for most of us. The answer given by Hemanth Palle is the easiest way to do it, It worked for me and the JS code wasn't necessary. The only problem that I've found is that according to W3Schools, The datalist tag is not supported in Internet Explorer 9 and earlier versions, or in Safari.

<!DOCTYPE html>
<script src=""></script>
<input list="browsers">
<datalist id="browsers">
  <option value="Internet Explorer">
  <option value="Firefox">
  <option value="Chrome">
  <option value="Opera">
  <option value="Safari">

"elseif" syntax in JavaScript

You are missing a space between else and if

It should be else if instead of elseif


else if(condition)



Download a file with Android, and showing the progress in a ProgressDialog

Don't forget to add permissions to your manifest file if you're gonna be downloading stuff from the internet!

<manifest xmlns:android=""

        <uses-sdk android:minSdkVersion="10" />

        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
        <uses-permission android:name="android.permission.INTERNET"></uses-permission>
        <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
        <uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>




How to get multiple counts with one SQL query?

Building on other posted answers.

Both of these will produce the right values:

select distributor_id,
    count(*) total,
    sum(case when level = 'exec' then 1 else 0 end) ExecCount,
    sum(case when level = 'personal' then 1 else 0 end) PersonalCount
from yourtable
group by distributor_id

SELECT a.distributor_id,
          (SELECT COUNT(*) FROM myTable WHERE level='personal' and distributor_id = a.distributor_id) as PersonalCount,
          (SELECT COUNT(*) FROM myTable WHERE level='exec' and distributor_id = a.distributor_id) as ExecCount,
          (SELECT COUNT(*) FROM myTable WHERE distributor_id = a.distributor_id) as TotalCount
       FROM myTable a ; 

However, the performance is quite different, which will obviously be more relevant as the quantity of data grows.

I found that, assuming no indexes were defined on the table, the query using the SUMs would do a single table scan, while the query with the COUNTs would do multiple table scans.

As an example, run the following script:

drop table t1

create table t1 (f1 int)

    insert into t1 values (1) 
    insert into t1 values (1) 
    insert into t1 values (2)
    insert into t1 values (2)
    insert into t1 values (2)
    insert into t1 values (3)
    insert into t1 values (3)
    insert into t1 values (3)
    insert into t1 values (3)
    insert into t1 values (4)
    insert into t1 values (4)
    insert into t1 values (4)
    insert into t1 values (4)
    insert into t1 values (4)

SELECT SUM(CASE WHEN f1 = 1 THEN 1 else 0 end),
SUM(CASE WHEN f1 = 2 THEN 1 else 0 end),
SUM(CASE WHEN f1 = 3 THEN 1 else 0 end),
SUM(CASE WHEN f1 = 4 THEN 1 else 0 end)
from t1

(select COUNT(*) from t1 where f1 = 1),
(select COUNT(*) from t1 where f1 = 2),
(select COUNT(*) from t1 where f1 = 3),
(select COUNT(*) from t1 where f1 = 4)

Highlight the 2 SELECT statements and click on the Display Estimated Execution Plan icon. You will see that the first statement will do one table scan and the second will do 4. Obviously one table scan is better than 4.

Adding a clustered index is also interesting. E.g.

Create clustered index t1f1 on t1(f1);
Update Statistics t1;

The first SELECT above will do a single Clustered Index Scan. The second SELECT will do 4 Clustered Index Seeks, but they are still more expensive than a single Clustered Index Scan. I tried the same thing on a table with 8 million rows and the second SELECT was still a lot more expensive.

Android - How to decode and decompile any APK file?

You can try this website Just upload the .apk file and rest of it will be done by this site.

How can I add reflection to a C++ application?

You need to look at what you are trying to do, and if RTTI will satisfy your requirements. I've implemented my own pseudo-reflection for some very specific purposes. For example, I once wanted to be able to flexibly configure what a simulation would output. It required adding some boilerplate code to the classes that would be output:

namespace {
  static bool b2 = Filter::Filterable<const MyObj>::Register("MyObject");

bool MyObj::BuildMap()
  Filterable<const OutputDisease>::AddAccess("time", &MyObj::time);
  Filterable<const OutputDisease>::AddAccess("person", &MyObj::id);
  return true;

The first call adds this object to the filtering system, which calls the BuildMap() method to figure out what methods are available.

Then, in the config file, you can do something like this:

FILTER-CLAUSE-1        person == 1773
FILTER-CLAUSE-2        time > 2000

Through some template magic involving boost, this gets translated into a series of method calls at run-time (when the config file is read), so it's fairly efficient. I wouldn't recommend doing this unless you really need to, but, when you do, you can do some really cool stuff.

How to align a div inside td element using CSS class

I cannot help you much without a small (possibly reduced) snippit of the problem. If the problem is what I think it is then it's because a div by default takes up 100% width, and as such cannot be aligned.

What you may be after is to align the inline elements inside the div (such as text) with text-align:center; otherwise you may consider setting the div to display:inline-block;

If you do go down the inline-block route then you may have to consider my favorite IE hack.

zoom:1; //IE only
*display:inline; //IE only

Happy Coding :)

Fastest Convert from Collection to List<T>

managementObjects.Cast<ManagementBaseObject>().ToList(); is a good choice.

You could improve performance by pre-initialising the list capacity:

    public static class Helpers
        public static List<T> CollectionToList<T>(this System.Collections.ICollection other)
            var output = new List<T>(other.Count);


            return output;

Find the index of a char in string?


returns 3

In general returns first occurrence index, if not present returns -1

How are software license keys generated?

I realize that this answer is about 10 years late to the party.

A good software license key/serial number generator consists of more than just a string of random characters or a value from some curve generator. Using a limited alphanumeric alphabet, data can be embedded into a short string (e.g. XXXX-XXXX-XXXX-XXXX) that includes all kinds of useful information such as:

  • Date created or the date the license expires
  • Product ID, product classification, major and minor version numbers
  • Custom bits like a hardware hash
  • Per-user hash checksum bits (e.g. the user enters their email address along with the license key and both pieces of information are used to calculate/verify the hash).

The license key data is then encrypted and then encoded using the limited alphanumeric alphabet. For online validation, the license server holds the secrets for decrypting the information. For offline validation, the decryption secret(s) are included with the software itself along with the decryption/validation code. Obviously, offline validation means the software isn't secure against someone making a keygen.

Probably the hardest part about creating a license key is figuring out how to cram as much data as possible into as few bytes as possible. Remember that users will be entering in their license keys by hand, so every bit counts and users don't want to type extremely long, complex strings in. 16 to 25 character license keys are the most common and balance how much data can be placed into a key vs. user tolerance for entering the key to unlock the software. Slicing up bytes into chunks of bits allows for more information to be included but does increase code complexity of both the generator and validator.

Encryption is a complex topic. In general, standard encryption algorithms like AES have block sizes that don't align with the goal of keeping license key lengths short. Therefore, most developers making their own license keys end up writing their own encryption algorithms (an activity which is frequently discouraged) or don't encrypt keys at all, which guarantees that someone will write a keygen. Suffice it to say that good encryption is hard to do right and a decent understanding of how Feistel networks and existing ciphers work are prerequisites.

Verifying a key is a matter of decoding and decrypting the string, verifying the hash/checksum, checking the product ID and major and minor version numbers in the data, verifying that the license hasn't expired, and doing whatever other checks need to be performed.

Writing a keygen is a matter of knowing what a license key consists of and then producing the same output that the original key generator produces. If the algorithm for license key verification is included in and used by the software, then it is just a matter of creating software that does the reverse of the verification process.

To see what the entire process looks like, here is a blog post I recently wrote that goes over choosing the license key length, the data layout, the encryption algorithm, and the final encoding scheme:

A practical, real-world implementation of the key generator and key verifier from the blog post can be seen here:

Documentation for the above class:

A production-ready open source license server that generates and manages license keys using the above serial number code can be found here:

The above license server supports both online and offline validation modes. A software product might start its existence with online only validation. When the software product is ready to retire and no longer supported, it can easily move to offline validation where all existing keys continue to work once the user upgrades to the very last version of the software that switches over to offline validation.

A live demo of how the above license server can be integrated into a website to sell software licenses plus an installable demo application can be found here (both the website and demo app are open source too):

Full disclosure: I'm the author of both the license server and the demo site software.

java.time.format.DateTimeParseException: Text could not be parsed at index 21

The following worked for me

import java.time.*;
import java.time.format.*;

public class Times {

  public static void main(String[] args) {
    final String dateTime = "2012-02-22T02:06:58.147Z";
    DateTimeFormatter formatter = DateTimeFormatter.ISO_INSTANT;
    final ZonedDateTime parsed = ZonedDateTime.parse(dateTime, formatter.withZone(ZoneId.of("UTC")));

and gave me output as


PHP, Get tomorrows date from date

Use DateTime:

To get tomorrow from now :

$d = new DateTime('+1day');
$tomorrow = $d->format('d/m/Y h.i.s');
echo $tomorrow;

Results : 28/06/2017 08.13.20

To get tomorrow from a date :

$d = new DateTime('2017/06/10 08.16.35 +1day')
$tomorrow = $d->format('d/m/Y h.i.s');
echo $tomorrow;

Results : 11/06/2017 08.16.35

Hope it helps!

Run an Ansible task only when the variable contains a specific string

If variable1 is a string, and you are searching for a substring in it, this should work:

when: '"value" in variable1'

if variable1 is an array or dict instead, in will search for the exact string as one of its items.

How to install a Notepad++ plugin offline?

Before using plugin NOTE plugins are usually in notepad 32 bit , 32 bit plugin is not compatible with 64 bit and vice versa(Recommendation use Notepad++ 32 bit)

Using Import in Notepad++
I tried Import plugin : However it didnt worked for me

Manual way
1. Download and extract .zip file having all .dll plugin files under the path
To download use following link or google the same
2. For placing inside plugins - Make sure to create a separated folder for each plugin

   + DSpellCheck
   + MIME Tools
   + Converter (etc.)

3. (if plugin contains ext_libs folder) Copy ext_libs to the root notepad folder,Usually contains few ddl files i.e.
C:\Program Files (x86)\Notepad++

If statements for Checkboxes

I'm making an assumption that you mean not checked. I don't have a C# compiler handy but:

if (checkbox1.Checked && !checkbox2.Checked)

else if (!checkbox1.Checked && checkbox2.Checked)


Command Prompt Error 'C:\Program' is not recognized as an internal or external command, operable program or batch file

If a directory has spaces in, put quotes around it. This includes the program you're calling, not just the arguments

"C:\Program Files\IAR Systems\Embedded Workbench 7.0\430\bin\icc430.exe" "F:\CP001\source\Meter\Main.c" -D Hardware_P20E -D Calibration_code -D _Optical -D _Configuration_TS0382 -o "F:\CP001\Temp\C20EO\Obj\" --no_cse --no_unroll --no_inline --no_code_motion --no_tbaa --debug -D__MSP430F425 -e --double=32 --dlib_config "C:\Program Files\IAR Systems\Embedded Workbench 7.0\430\lib\dlib\dl430fn.h" -Ol --multiplier=16 --segment __data16=DATA16 --segment __data20=DATA20

Debugging with Android Studio stuck at "Waiting For Debugger" forever

Debugger stopped connecting for me today and nothing worked until I tried the following:

Go to Run, Edit-Configurations, Miscellaneous Tab, uncheck 'skip installation if APK has not changed' Apply, OK.

Debugger started to connect again.

IntelliJ IDEA "cannot resolve symbol" and "cannot resolve method"

I was facing the same problem when import projects into IntelliJ.

for in my case first, check SDK details and check you have configured JDK correctly or not.

Go to File-> Project Structure-> platform Settings-> SDKs

Check your JDK is correct or not.

enter image description here

Next, I Removed project from IntelliJ and delete all IntelliJ and IDE related files and folder from the project folder (.idea, .settings, .classpath, dependency-reduced-pom). Also, delete the target folder and re-import the project.

The above solution worked in my case.

How to read a list of files from a folder using PHP?

There is also a really simple way to do this with the help of the RecursiveTreeIterator class, answered here:

How to extract 1 screenshot for a video with ffmpeg at a given time?

FFMpeg can do this by seeking to the given timestamp and extracting exactly one frame as an image, see for instance:

ffmpeg -i input_file.mp4 -ss 01:23:45 -vframes 1 output.jpg

Let's explain the options:

-i input file           the path to the input file
-ss 01:23:45            seek the position to the specified timestamp
-vframes 1              only handle one video frame
output.jpg              output filename, should have a well-known extension

The -ss parameter accepts a value in the form HH:MM:SS[.xxx] or as a number in seconds. If you need a percentage, you need to compute the video duration beforehand.

How to correctly use "section" tag in HTML5?

You can definitely use the section tag as a container. It is there to group content in a more semantically significant way than with a div or as the html5 spec says:

The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading.

How to limit the maximum value of a numeric field in a Django model?

Here is the best solution if you want some extra flexibility and don't want to change your model field. Just add this custom validator:

from django.core.exceptions import ValidationError      

class validate_range_or_null(object):
    compare = lambda self, a, b, c: a > c or a < b
    clean = lambda self, x: x
    message = ('Ensure this value is between %(limit_min)s and %(limit_max)s (it is %(show_value)s).')
    code = 'limit_value'

    def __init__(self, limit_min, limit_max):
        self.limit_min = limit_min
        self.limit_max = limit_max

    def __call__(self, value):
        cleaned = self.clean(value)
        params = {'limit_min': self.limit_min, 'limit_max': self.limit_max, 'show_value': cleaned}
        if value:  # make it optional, remove it to make required, or make required on the model
            if, self.limit_min, self.limit_max):
                raise ValidationError(self.message, code=self.code, params=params)

And it can be used as such:

class YourModel(models.Model):

    no_dependents = models.PositiveSmallIntegerField("How many dependants?", blank=True, null=True, default=0, validators=[validate_range_or_null(1,100)])

The two parameters are max and min, and it allows nulls. You can customize the validator if you like by getting rid of the marked if statement or change your field to be blank=False, null=False in the model. That will of course require a migration.

Note: I had to add the validator because Django does not validate the range on PositiveSmallIntegerField, instead it creates a smallint (in postgres) for this field and you get a DB error if the numeric specified is out of range.

Hope this helps :) More on Validators in Django.

PS. I based my answer on BaseValidator in django.core.validators, but everything is different except for the code.

ASP.NET MVC Ajax Error handling

I did a quick solution because I was short of time and it worked ok. Although I think the better option is use an Exception Filter, maybe my solution can help in the case that a simple solution is needed.

I did the following. In the controller method I returned a JsonResult with a property "Success" inside the Data:

    public JsonResult UpdateEmployeeConfig(EmployeConfig employeToSave) 
        if (!ModelState.IsValid)
            return new JsonResult
                Data = new { ErrorMessage = "Model is not valid", Success = false },
                ContentEncoding = System.Text.Encoding.UTF8,
                JsonRequestBehavior = JsonRequestBehavior.DenyGet
            MyDbContext db = new MyDbContext();

            db.Entry(employeToSave).State = EntityState.Modified;

            DTO.EmployeConfig user = (DTO.EmployeConfig)Session["EmployeLoggin"];

            if (employeToSave.Id == user.Id)
                user.Company = employeToSave.Company;
                user.Language = employeToSave.Language;
                user.Money = employeToSave.Money;
                user.CostCenter = employeToSave.CostCenter;

                Session["EmployeLoggin"] = user;
        catch (Exception ex) 
            return new JsonResult
                Data = new { ErrorMessage = ex.Message, Success = false },
                ContentEncoding = System.Text.Encoding.UTF8,
                JsonRequestBehavior = JsonRequestBehavior.DenyGet

        return new JsonResult() { Data = new { Success = true }, };

Later in the ajax call I just asked for this property to know if I had an exception:

    url: 'UpdateEmployeeConfig',
    type: 'PUT',
    data: JSON.stringify(EmployeConfig),
    contentType: "application/json;charset=utf-8",
    success: function (data) {
        if (data.Success) {
            //This is for the example. Please do something prettier for the user, :)
            alert('All was really ok');                                           
        else {
            alert('Oups.. we had errors: ' + data.ErrorMessage);
    error: function (request, status, error) {
       alert('oh, errors here. The call to the server is not working.')

Hope this helps. Happy code! :P

The FastCGI process exited unexpectedly

For Issue C:\PHP\php-cgi.exe - The FastCGI process exited unexpectedly.

I resolved this by installing the Visual C++ Redistributable for Visual Studio 2015.(Microsoft Visual C++ 2015 Redistributable Update 3) and Visual C++ Redistributable for Visual Studio 2012 Update 4 in 32 and 64bit versions. and also make sure in file cgi.fix_pathinfo=0 enabled.

How can I use optional parameters in a T-SQL stored procedure?

The answer from @KM is good as far as it goes but fails to fully follow up on one of his early bits of advice;

..., ignore compact code, ignore worrying about repeating code, ...

If you are looking to achieve the best performance then you should write a bespoke query for each possible combination of optional criteria. This might sound extreme, and if you have a lot of optional criteria then it might be, but performance is often a trade-off between effort and results. In practice, there might be a common set of parameter combinations that can be targeted with bespoke queries, then a generic query (as per the other answers) for all other combinations.

    @FirstName varchar(25) = null,
    @LastName varchar(25) = null,
    @Title varchar(25) = null

    IF (@FirstName IS NOT NULL AND @LastName IS NULL AND @Title IS NULL)
        -- Search by first name only
        SELECT ID, FirstName, LastName, Title
        FROM tblUsers
            FirstName = @FirstName

    ELSE IF (@FirstName IS NULL AND @LastName IS NOT NULL AND @Title IS NULL)
        -- Search by last name only
        SELECT ID, FirstName, LastName, Title
        FROM tblUsers
            LastName = @LastName

    ELSE IF (@FirstName IS NULL AND @LastName IS NULL AND @Title IS NOT NULL)
        -- Search by title only
        SELECT ID, FirstName, LastName, Title
        FROM tblUsers
            Title = @Title

        -- Search by first and last name
        SELECT ID, FirstName, LastName, Title
        FROM tblUsers
            FirstName = @FirstName
            AND LastName = @LastName

        -- Search by any other combination
        SELECT ID, FirstName, LastName, Title
        FROM tblUsers
                (@FirstName IS NULL OR (FirstName = @FirstName))
            AND (@LastName  IS NULL OR (LastName  = @LastName ))
            AND (@Title     IS NULL OR (Title     = @Title    ))


The advantage of this approach is that in the common cases handled by bespoke queries the query is as efficient as it can be - there's no impact by the unsupplied criteria. Also, indexes and other performance enhancements can be targeted at specific bespoke queries rather than trying to satisfy all possible situations.

Need a row count after SELECT statement: what's the optimal SQL approach?

There are only two ways to be 100% certain that the COUNT(*) and the actual query will give consistent results:

  • Combined the COUNT(*) with the query, as in your Approach 2. I recommend the form you show in your example, not the correlated subquery form shown in the comment from kogus.
  • Use two queries, as in your Approach 1, after starting a transaction in SNAPSHOT or SERIALIZABLE isolation level.

Using one of those isolation levels is important because any other isolation level allows new rows created by other clients to become visible in your current transaction. Read the MSDN documentation on SET TRANSACTION ISOLATION for more details.

How do I uniquely identify computers visiting my web site?

There is a popular method called canvas fingerprinting, described in this scientific article: The Web Never Forgets: Persistent Tracking Mechanisms in the Wild. Once you start looking for it, you'll be surprised how frequently it is used. The method creates a unique fingerprint, which is consistent for each browser/hardware combination.

The article also reviews other persistent tracking methods, like evercookies, respawning http and Flash cookies, and cookie syncing.

More info about canvas fingerprinting here:

Proper way of checking if row exists in table in PL/SQL block

Select 'YOU WILL SEE ME' as ANSWER from dual
where exists (select 1 from dual where 1 = 1);

Select 'YOU CAN NOT SEE ME' as ANSWER from dual
where exists (select 1 from dual where 1 = 0);

Select 'YOU WILL SEE ME, TOO' as ANSWER from dual
where not exists (select 1 from dual where 1 = 0);

Exception Error c0000005 in VC++

Exception code c0000005 is the code for an access violation. That means that your program is accessing (either reading or writing) a memory address to which it does not have rights. Most commonly this is caused by:

  • Accessing a stale pointer. That is accessing memory that has already been deallocated. Note that such stale pointer accesses do not always result in access violations. Only if the memory manager has returned the memory to the system do you get an access violation.
  • Reading off the end of an array. This is when you have an array of length N and you access elements with index >=N.

To solve the problem you'll need to do some debugging. If you are not in a position to get the fault to occur under your debugger on your development machine you should get a crash dump file and load it into your debugger. This will allow you to see where in the code the problem occurred and hopefully lead you to the solution. You'll need to have the debugging symbols associated with the executable in order to see meaningful stack traces.

Creating a left-arrow button (like UINavigationBar's "back" style) on a UIToolbar

You can find the source images by extracting them from Other.artwork in UIKit ${SDKROOT}/System/Library/Frameworks/UIKit.framework/Other.artwork. The modding community has some tools for extracting them, here. Once you extract the image you can write some code to recolor it as necessary and set it as the button image. Whether or not you can actually ship such a thing (since you are embedding derived artwork) might be a little dicey, so maybe you want to talk to a lawyer.

how to put image in a bundle and pass it to another activity

So you can do it like this, but the limitation with the Parcelables is that the payload between activities has to be less than 1MB total. It's usually better to save the Bitmap to a file and pass the URI to the image to the next activity.

 protected void onCreate(Bundle savedInstanceState) {     setContentView(R.layout.my_layout);     Bitmap bitmap = getIntent().getParcelableExtra("image");     ImageView imageView = (ImageView) findViewById(;     imageView.setImageBitmap(bitmap);  } 

Default interface methods are only supported starting with Android N

My project use ButterKnife and Retro lambda, setting JavaVersion.VERSION_1_8 will not work. It always blames at ButterKnife static interface function until I found this Migrate from Retrolambda


Just add JavaVersion.VERSION_1_8 and completely REMOVE retrolambda from your project. It will build successfully.

HTTP redirect: 301 (permanent) vs. 302 (temporary)

Mostly 301 vs 302 is important for indexing in search engines, as their crawlers take this into account and transfer PageRank when using 301.

See Peter Lee's answer for more details.

is there a function in lodash to replace matched item

Using lodash unionWith function, you can accomplish a simple upsert to an object. The documentation states that if there is a match, it will use the first array. Wrap your updated object in [ ] (array) and put it as the first array of the union function. Simply specify your matching logic and if found it will replace it and if not it will add it


let contacts = [
     {type: 'email', desc: 'work', primary: true, value: 'email prim'}, 
     {type: 'phone', desc: 'cell', primary: true, value:'phone prim'},
     {type: 'phone', desc: 'cell', primary: false,value:'phone secondary'},
     {type: 'email', desc: 'cell', primary: false,value:'email secondary'}

// Update contacts because found a match
_.unionWith([{type: 'email', desc: 'work', primary: true, value: 'email updated'}], contacts, (l, r) => l.type == r.type && l.primary == r.primary)

// Add to contacts - no match found
_.unionWith([{type: 'fax', desc: 'work', primary: true, value: 'fax added'}], contacts, (l, r) => l.type == r.type && l.primary == r.primary)

How to see which flags -march=native will activate?

You can use the -Q --help=target options:

gcc -march=native -Q --help=target ...

The -v option may also be of use.

You can see the documentation on the --help option here.

How do I hide an element on a click event anywhere outside of the element?

   $("body").click(function(event) {_x000D_
   if($('class') != '1' && $('class') != 'div3'){_x000D_
    }); _x000D_
<script src=""></script>_x000D_
<button class="1">Click to fade in boxes</button><br><br>_x000D_
<body style="width:100%;height:200px;background-color:pink;">_x000D_
<div class="div3" style="width:80px;height:80px;display:none;background-color:blue;"></div><body>

Hide Twitter Bootstrap nav collapse on click

If you have scrolling problems after using the jQuery solution described above, e.g.


then this is caused by Bootstrap adding the CSS class overlay-active in the parent element. This can even go up to your body element.

To solve this you have to remove this class:

<script type="text/javascript">



Objective-C : BOOL vs bool

As mentioned above BOOL could be an unsigned char type depending on your architecture, while bool is of type int. A simple experiment will show the difference why BOOL and bool can behave differently:

bool ansicBool = 64;
if(ansicBool != true) printf("This will not print\n");

printf("Any given vlaue other than 0 to ansicBool is evaluated to %i\n", ansicBool);

BOOL objcBOOL = 64;
if(objcBOOL != YES) printf("This might print depnding on your architecture\n");

printf("BOOL will keep whatever value you assign it: %i\n", objcBOOL);

if(!objcBOOL) printf("This will not print\n");

printf("! operator will zero objcBOOL %i\n", !objcBOOL);

if(!!objcBOOL) printf("!! will evaluate objcBOOL value to %i\n", !!objcBOOL);

To your surprise if(objcBOOL != YES) will evaluates to 1 by the compiler, since YES is actually the character code 1, and in the eyes of compiler, character code 64 is of course not equal to character code 1 thus the if statement will evaluate to YES/true/1 and the following line will run. However since a none zero bool type always evaluates to the integer value of 1, the above issue will not effect your code. Below are some good tips if you want to use the Objective-C BOOL type vs the ANSI C bool type:

  • Always assign the YES or NO value and nothing else.
  • Convert BOOL types by using double not !! operator to avoid unexpected results.
  • When checking for YES use if(!myBool) instead of if(myBool != YES) it is much cleaner to use the not ! operator and gives the expected result.

Check if record exists from controller in Rails

When you call Business.where(:user_id => you will get an array. This Array may have no objects or one or many objects in it, but it won't be null. Thus the check == nil will never be true.

You can try the following:

if Business.where(:user_id => == 0

So you check the number of elements in the array and compare them to zero.

or you can try:

if Business.find_by_user_id(

this will return one or nil.

Copy output of a JavaScript variable to the clipboard

Nowadays there is a new(ish) API to do this directly. It works on modern browsers and on HTTPS (and localhost) only. Not supported by IE11.

IE11 has its own API.

And the workaround in the accepted answer can be used for unsecure hosts.

function copyToClipboard (text) {
  if (navigator.clipboard) { // default: modern asynchronous API
    return navigator.clipboard.writeText(text);
  } else if (window.clipboardData && window.clipboardData.setData) {     // for IE11
    window.clipboardData.setData('Text', text);
    return Promise.resolve();
  } else {
    // workaround: create dummy input
    const input = h('input', { type: 'text' });
    input.value = text;
    return Promise.resolve();

Note: it uses Hyperscript to create the input element (but should be easy to adapt)

There is no need to make the input invisible, as it is added and removed so fast. Also when hidden (even using some clever method) some browsers will detect it and prevent the copy operation.

Use Toast inside Fragment

To help another people with my same problem, the complete answer to Use Toast inside Fragment is:

Activity activity = getActivity();

public void onClick(View arg0) {


How to playback MKV video in web browser?

HTML5 and the VLC web plugin were a no go for me but I was able to get this work using the following setup:

DivX Web Player (NPAPI browsers only)

AC3 Audio Decoder

And here is the HTML:

<embed id="divxplayer" type="video/divx" width="1024" height="768" 
src ="path_to_file" autoPlay=\"true\" 

The DivX player seems to allow for a much wider array of video and audio options than the native HTML5, so far I am very impressed by it.

Setup a Git server with msysgit on Windows

You don't need SSH for sharing git. If you're on a LAN or VPN, you can export a git project as a shared folder, and mount it on a remote machine. Then configure the remote repo using "file://" URLs instead of "git@" URLs. Takes all of 30 seconds. Done!

How to validate inputs dynamically created using ng-repeat, ng-show (angular)

Use the ng-form directive inside of the tag in which you are using the ng-repeat directive. You can then use the scope created by the ng-form directive to reference a generic name. For example:

    <div class="form-group col-sm-6" data-ng-form="subForm" data-ng-repeat="field in justificationInfo.justifications"">

        <label for="{{field.label}}"><h3>{{field.label}}</h3></label>
        <i class="icon-valid" data-ng-show="subForm.input.$dirty && subForm.input.$valid"></i>
        <i class="icon-invalid" data-ng-show="subForm.input.$dirty && subForm.input.$invalid"></i>
        <textarea placeholder="{{field.placeholder}}" class="form-control" id="{{field.label}}" name="input" type="text" rows="3" data-ng-model="field.value" required>{{field.value}}</textarea>


Credit to:

Conversion between UTF-8 ArrayBuffer and String

If you don't want to use any external polyfill library, you can use this function provided by the Mozilla Developer Network website:

function utf8ArrayToString(aBytes) {_x000D_
    var sView = "";_x000D_
    for (var nPart, nLen = aBytes.length, nIdx = 0; nIdx < nLen; nIdx++) {_x000D_
        nPart = aBytes[nIdx];_x000D_
        sView += String.fromCharCode(_x000D_
            nPart > 251 && nPart < 254 && nIdx + 5 < nLen ? /* six bytes */_x000D_
                /* (nPart - 252 << 30) may be not so safe in ECMAScript! So...: */_x000D_
                (nPart - 252) * 1073741824 + (aBytes[++nIdx] - 128 << 24) + (aBytes[++nIdx] - 128 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 247 && nPart < 252 && nIdx + 4 < nLen ? /* five bytes */_x000D_
                (nPart - 248 << 24) + (aBytes[++nIdx] - 128 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 239 && nPart < 248 && nIdx + 3 < nLen ? /* four bytes */_x000D_
                (nPart - 240 << 18) + (aBytes[++nIdx] - 128 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 223 && nPart < 240 && nIdx + 2 < nLen ? /* three bytes */_x000D_
                (nPart - 224 << 12) + (aBytes[++nIdx] - 128 << 6) + aBytes[++nIdx] - 128_x000D_
            : nPart > 191 && nPart < 224 && nIdx + 1 < nLen ? /* two bytes */_x000D_
                (nPart - 192 << 6) + aBytes[++nIdx] - 128_x000D_
            : /* nPart < 127 ? */ /* one byte */_x000D_
    return sView;_x000D_
let str = utf8ArrayToString([50,72,226,130,130,32,43,32,79,226,130,130,32,226,135,140,32,50,72,226,130,130,79]);_x000D_
// Must show 2H2 + O2 ? 2H2O_x000D_

JQuery - Get select value

val() returns the value of the <select> element, i.e. the value attribute of the selected <option> element.

Since you actually want the inner text of the selected <option> element, you should match that element and use text() instead:

var nationality = $("#dancerCountry option:selected").text();

How to connect to a remote Git repository?

Like you said remote_repo_url is indeed the IP of the server, and yes it needs to be added on each PC, but it's easier to understand if you create the server first then ask each to clone it.

There's several ways to connect to the server, you can use ssh, http, or even a network drive, each has it's pros and cons. You can refer to the documentation about protocols and how to connect to the server

You can check the rest of chapter 4 for more detailed information, as it's talking about how to set up your own server

What is a superfast way to read large files line-by-line in VBA?

You can use Scripting.FileSystemObject to do that thing. From the Reference:

The ReadLine method allows a script to read individual lines in a text file. To use this method, open the text file, and then set up a Do Loop that continues until the AtEndOfStream property is True. (This simply means that you have reached the end of the file.) Within the Do Loop, call the ReadLine method, store the contents of the first line in a variable, and then perform some action. When the script loops around, it will automatically drop down a line and read the second line of the file into the variable. This will continue until each line has been read (or until the script specifically exits the loop).

And a quick example:

Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.OpenTextFile("C:\FSO\ServerList.txt", 1)
Do Until objFile.AtEndOfStream
 strLine = objFile.ReadLine
 MsgBox strLine

How to create byte array from HttpPostedFile

For images if your using Web Pages v2 use the WebImage Class

var webImage = new System.Web.Helpers.WebImage(Request.Files[0].InputStream);
byte[] imgByteArray = webImage.GetBytes();

What are the differences between LDAP and Active Directory?

Active Directory isn't just an implementation of LDAP by Microsoft, that is only a small part of what AD is. Active Directory is (in an overly simplified way) a service that provides LDAP based authentication with Kerberos based Authorization.

Of course their LDAP and Kerberos implementations in AD are not exactly 100% interoperable with other LDAP/Kerberos implementations...

Conditional Logic on Pandas DataFrame

Just compare the column with that value:

In [9]: df = pandas.DataFrame([1,2,3,4], columns=["data"])

In [10]: df
0     1
1     2
2     3
3     4

In [11]: df["desired"] = df["data"] > 2.5
In [11]: df
   data desired
0     1   False
1     2   False
2     3    True
3     4    True

internet explorer 10 - how to apply grayscale filter?

Use this jQuery plugin

That seems to be the only one cross-browser solution. Plus it has a nice fade in and fade out effect.

    hoverEffect : true, // default true
    // set the path to BnWWorker.js for a superfast implementation
    webworkerPath : false,
    // to invert the hover effect
    invertHoverEffect: false,
    // this option works only on the modern browsers ( on IE lower than 9 it remains always 1)
    speed: { //this property could also be just speed: value for both fadeIn and fadeOut
        fadeIn: 200, // 200ms for fadeIn animations
        fadeOut: 800 // 800ms for fadeOut animations
    onImageReady:function(img) {
        // this callback gets executed anytime an image is converted

Generating UML from C++ code?

I've developed a tool called Doxygraph which can parse the XML generated by Doxygen and turn it into an interactive UML class diagram which you can view in a web browser or import into any software that can read Graphviz "dot" files.

How to make a vertical line in HTML

You can use hr (horizontal line) tag and than rotate it 90 degree with css below

hr {   

Create a sample login page using servlet and JSP?

You're comparing the message with the empty string using ==.

First, your comparison is wrong because the message will be null (and not the empty string).

Second, it's wrong because Objects must be compared with equals() and not with ==.

Third, it's wrong because you should avoid scriptlets in JSP, and use the JSP EL, the JSTL, and other custom tags instead:

<c:id test="${!empty message}">
    <c:out value="${message}"/>

How to revert the last migration?

there is a good library to use its called djagno-nomad, although not directly related to the question asked, thought of sharing this,

scenario: most of the time when switching to project, we feel like it should revert our changes that we did on this current branch, that's what exactly this library does, checkout below

better way to drop nan rows in pandas

Just in case commands in previous answers doesn't work, Try this: dat.dropna(subset=['x'], inplace = True)

How to use Spring Boot with MySQL database and JPA?

When moving classes into specific packages like repository, controller, domain just the generic @SpringBootApplication is not enough.

You will have to specify the base package for component scan



@EnableJpaRepositories(basePackages = "repository")

is also needed, so spring data will know where to look into for repository interfaces.

Difference between applicationContext.xml and spring-servlet.xml in Spring Framework

One more point I want to add. In spring-servlet.xml we include component scan for Controller package. In following example we include filter annotation for controller package.

<!-- Scans for annotated @Controllers in the classpath -->
<context:component-scan base-package="org.test.web" use-default-filters="false">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>

In applicationcontext.xml we add filter for remaining package excluding controller.

<context:component-scan base-package="org.test">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>

No Android SDK found - Android Studio

I just encountered and solve a similar problem.

First you should check the directory like other threads described. Then you can check whether the Build tool version matches your SDK version.

(e.g. for my project, in build.gradle file, you have:)

android { compileSdkVersion 21 buildToolsVersion "21.1.1" }

and then open you SDK manager, make sure you have the same version of sdk(21.1.1) installed in the selected directoriy:

If not, install it and restart Android Studio. It works for me.

I've also seen other guys saying run Android Studio as administrator would also help:

how to get 2 digits after decimal point in tsql?

You could cast it to DECIMAL and specify the scale to be 2 digits

decimal and numeric

So, something like

SELECT @i / 3


I would however recomend that this be done in the UI/Report layer, as this will cuase loss of precision.

Formatting (in my opinion) should happen on the UI/Report/Display level.

using nth-child in tables tr td

Current css version still doesn't support selector find by content. But there is a way, by using css selector find by attribute, but you have to put some identifier on all of the <td> that have $ inside. Example: using nth-child in tables tr td


    <td data-rel='$'>$</td>


table tr td[data-rel='$'] {
    background-color: #333;
    color: white;

Please try these example.

table tr td[data-content='$'] {_x000D_
    background-color: #333;_x000D_
    color: white;_x000D_
<table border="1">_x000D_
        <td data-content='$'>$</td>_x000D_
        <td data-content='$'>$</td>_x000D_
        <td data-content='$'>$</td>_x000D_

Fatal error: Call to undefined function mb_strlen()

In case Google search for this error

Call to undefined function mb_ereg_match()

takes somebody to this thread. Installing php-mbstring resolves it too.

Ubuntu 18.04.1, PHP 7.2.10

sudo apt-get install php7.2-mbstring

How to check whether a pandas DataFrame is empty?

1) If a DataFrame has got Nan and Non Null values and you want to find whether the DataFrame
is empty or not then try this code.
2) when this situation can happen? 
This situation happens when a single function is used to plot more than one DataFrame 
which are passed as parameter.In such a situation the function try to plot the data even 
when a DataFrame is empty and thus plot an empty figure!.
It will make sense if simply display 'DataFrame has no data' message.
3) why? 
if a DataFrame is empty(i.e. contain no data at all.Mind you DataFrame with Nan values 
is considered non empty) then it is desirable not to plot but put out a message :
Suppose we have two DataFrames df1 and df2.
The function myfunc takes any DataFrame(df1 and df2 in this case) and print a message 
if a DataFrame is empty(instead of plotting):
df1                     df2
col1 col2           col1 col2 
Nan   2              Nan  Nan 
2     Nan            Nan  Nan  

and the function:

def myfunc(df):
  if (df.count().sum())>0: ##count the total number of non Nan values.Equal to 0 if DataFrame is empty
     print('not empty')
     display a message instead of plotting if it is empty

how to destroy bootstrap modal window completely?

I don't know how this may sound but this work for me...........


How to use an arraylist as a prepared statement parameter

If you have ArrayList then convert into Array[Object]

ArrayList<String> list = new ArrayList<String>();
PreparedStatement pstmt = 
            conn.prepareStatement("select * from employee where id in (?)");
Array array = conn.createArrayOf("VARCHAR", list.toArray());
pstmt.setArray(1, array);
ResultSet rs = pstmt.executeQuery();

How to center Font Awesome icons horizontally?

If your icons are in an icon stack you can use the following code:

.icon-stack{ margin: auto; display: block; } 

HTML5 video - show/hide controls programmatically

Here's how to do it:

var myVideo = document.getElementById("my-video")    
myVideo.controls = false;

Working example:

See all available properties, methods and events here:

Generating a list of pages (not posts) without the index file

I can offer you a jquery solution

add this in your <head></head> tag

<script type="text/javascript" src=""></script>

add this after </ul>

 <script> $('ul li:first').remove(); </script> 

How do I fetch only one branch of a remote Git repository?

git version: 2.74

This is how I do it:

git remote add [REMOTE-NAME] [REMOTE-URL]
git fetch [REMOTE-NAME] -- [BRANCH]

How to Call Controller Actions using JQuery in ASP.NET MVC

In response to the above post I think it needs this line instead of your line:-

var strMethodUrl = '@Url.Action("SubMenu_Click", "Logging")?param1='+value1+' &param2='+value2

Or else you send the actual strings value1 and value2 to the controller.

However, for me, it only calls the controller once. It seems to hit 'receieveResponse' each time, but a break point on the controller method shows it is only hit 1st time until a page refresh.

Here is a working solution. For the cshtml page:-

   <button type="button" onclick="ButtonClick();"> Call &raquo;</button>

    function ButtonClick()
        callControllerMethod2("1", "2");
    function callControllerMethod2(value1, value2)
        var response = null;
            async: true,
            url: "Logging/SubMenu_Click?param1=" + value1 + " &param2=" + value2,
            cache: false,
            dataType: "json",
            success: function (data) { receiveResponse(data); }
    function receiveResponse(response)
        if (response != null)
            for (var i = 0; i < response.length; i++)

And for the controller:-

public class A
    public string Id { get; set; }
    public string Data { get; set; }

public JsonResult SubMenu_Click(string param1, string param2)
    A[] arr = new A[] {new A(){ Id = "1", Data = DateTime.Now.Millisecond.ToString() } };
    return Json(arr , JsonRequestBehavior.AllowGet);

You can see the time changing each time it is called, so there is no caching of the values...

Convert XML String to Object

Create a DTO as CustomObject

Use below method to convert XML String to DTO using JAXB

private static CustomObject getCustomObject(final String ruleStr) {
    CustomObject customObject = null;
    try {
        JAXBContext jaxbContext = JAXBContext.newInstance(CustomObject.class);
        final StringReader reader = new StringReader(ruleStr);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        customObject = (CustomObject) jaxbUnmarshaller.unmarshal(reader);
    } catch (JAXBException e) {"getCustomObject parse error: ", e);
    return customObject;

Stateless vs Stateful

Money transfered online form one account to another account is stateful, because the receving account has information about the sender. Handing over cash from a person to another person, this transaction is statless, because after cash is recived the identity of the giver is not there with the cash.

How to create a circular ImageView in Android?

I too needed a rounded ImageView, I used the below code, you can modify it accordingly:

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;

public class RoundedImageView extends ImageView {

    public RoundedImageView(Context context) {

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);

    public RoundedImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    protected void onDraw(Canvas canvas) {

        Drawable drawable = getDrawable();

        if (drawable == null) {

        if (getWidth() == 0 || getHeight() == 0) {
        Bitmap b = ((BitmapDrawable) drawable).getBitmap();
        Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);

        int w = getWidth();
        int h = getHeight();

        Bitmap roundBitmap = getCroppedBitmap(bitmap, w);
        canvas.drawBitmap(roundBitmap, 0, 0, null);


    public static Bitmap getCroppedBitmap(Bitmap bmp, int radius) {
        Bitmap sbmp;

        if (bmp.getWidth() != radius || bmp.getHeight() != radius) {
            float smallest = Math.min(bmp.getWidth(), bmp.getHeight());
            float factor = smallest / radius;
            sbmp = Bitmap.createScaledBitmap(bmp,
                    (int) (bmp.getWidth() / factor),
                    (int) (bmp.getHeight() / factor), false);
        } else {
            sbmp = bmp;

        Bitmap output = Bitmap.createBitmap(radius, radius, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final String color = "#BAB399";
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, radius, radius);

        canvas.drawARGB(0, 0, 0, 0);
        canvas.drawCircle(radius / 2 + 0.7f, radius / 2 + 0.7f,
                radius / 2 + 0.1f, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(sbmp, rect, rect, paint);

        return output;


How do I measure time elapsed in Java?

Unfortunately, none of the ten answers posted so far are quite right.

If you are measuring elapsed time, and you want it to be correct, you must use System.nanoTime(). You cannot use System.currentTimeMillis(), unless you don't mind your result being wrong.

The purpose of nanoTime is to measure elapsed time, and the purpose of currentTimeMillis is to measure wall-clock time. You can't use the one for the other purpose. The reason is that no computer's clock is perfect; it always drifts and occasionally needs to be corrected. This correction might either happen manually, or in the case of most machines, there's a process that runs and continually issues small corrections to the system clock ("wall clock"). These tend to happen often. Another such correction happens whenever there is a leap second.

Since nanoTime's purpose is to measure elapsed time, it is unaffected by any of these small corrections. It is what you want to use. Any timings currently underway with currentTimeMillis will be off -- possibly even negative.

You may say, "this doesn't sound like it would ever really matter that much," to which I say, maybe not, but overall, isn't correct code just better than incorrect code? Besides, nanoTime is shorter to type anyway.

Previously posted disclaimers about nanoTime usually having only microsecond precision are valid. Also it can take more than a whole microsecond to invoke, depending on circumstances (as can the other one), so don't expect to time very very small intervals correctly.

When is the finalize() method called in Java?

finalize method is not guaranteed.This method is called when the object becomes eligible for GC. There are many situations where the objects may not be garbage collected.

Creating and Update Laravel Eloquent

like @JuanchoRamone posted above (thank @Juancho) it's very useful for me, but if your data is array you should modify a little like this:

public static function createOrUpdate($data, $keys) {
    $record = self::where($keys)->first();
    if (is_null($record)) {
        return self::create($data);
    } else {
        return $record->update($data);

Read properties file outside JAR file

I did it by other way.

Properties prop = new Properties();
    try {

        File jarPath=new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath());
        String propertiesPath=jarPath.getParentFile().getAbsolutePath();
        System.out.println(" propertiesPath-"+propertiesPath);
        prop.load(new FileInputStream(propertiesPath+"/"));
    } catch (IOException e1) {
  1. Get Jar file path.
  2. Get Parent folder of that file.
  3. Use that path in InputStreamPath with your properties file name.

How to check currently internet connection is available or not in android

You can try this:

private boolean isConnectedToWifi(){
    ConnectivityManager cm = (ConnectivityManager) getApplication().getSystemService(Context.CONNECTIVITY_SERVICE);
    if(cm != null){    
        NetworkCapabilities nc = cm.getNetworkCapabilities(cm.getActiveNetwork());
        return nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI);
    return false;

Retrieving a List from a in Java 8

If you don't mind using 3rd party libraries, AOL's cyclops-react lib (disclosure I am a contributor) has extensions for all JDK Collection types, including List. The ListX interface extends java.util.List and adds a large number of useful operators, including filter.

You can simply write-

ListX<Long> sourceLongList = ListX.of(1L, 10L, 50L, 80L, 100L, 120L, 133L, 333L);
ListX<Long> targetLongList = sourceLongList.filter(l -> l > 100);

ListX also can be created from an existing List (via ListX.fromIterable)

Best way to convert an ArrayList to a string

This is quite an old conversation by now and apache commons are now using a StringBuilder internally:

This will as we know improve performance, but if performance is critical then the method used might be somewhat inefficient. Whereas the interface is flexible and will allow for consistent behaviour across different Collection types it is somewhat inefficient for Lists, which is the type of Collection in the original question.

I base this in that we are incurring some overhead which we would avoid by simply iterating through the elements in a traditional for loop. Instead there are some additional things happening behind the scenes checking for concurrent modifications, method calls etc. The enhanced for loop will on the other hand result in the same overhead since the iterator is used on the Iterable object (the List).

How to set a default value in react-select

If you've come here for react-select v2, and still having trouble - version 2 now only accepts an object as value, defaultValue, etc.

That is, try using value={{value: 'one', label: 'One'}}, instead of just value={'one'}.

How to remove extension from string (only real extension!)

$filename = pathinfo('', PATHINFO_FILENAME); // returns ''

Email and phone Number Validation in android

try this:

extMobileNo.addTextChangedListener(new MyTextWatcher(extMobileNo));

private boolean validateMobile()    {   

    String mobile =extMobileNo.getText().toString().trim();
    if(mobile.isEmpty()||!isValidMobile(mobile)||extMobileNo.getText().toString().toString().length()<10 || mobile.length()>13 )

        return false;

    else {

    return true;

private static boolean isValidMobile(String mobile)
    return !TextUtils.isEmpty(mobile)&& Patterns.PHONE.matcher(mobile).matches();

Using union and count(*) together in SQL query

select, count (*)
from (select name from Results 
      select name from Archive_Results) as T1
group by order by

Retrofit 2 - Dynamic URL

You can use this :


Call<List<User>> groupList(@Path("id") int groupId, @Query("sort") String sort);

For more information see documentation

MongoDB - Update objects in a document's array (nested updating)

We can use $set operator to update the nested array inside object filed update the value

       "_id" : ObjectId("5bd3013ac714ea4959f80115"), 
       "" : "United States of America"
   { $set: 
           "geolocation.$.country" : "USA"

How do I return a char array from a function?

With Boost:

boost::array<char, 10> testfunc()
    boost::array<char, 10> str;

    return str;

A normal char[10] (or any other array) can't be returned from a function.

What is a StackOverflowError?

This is a typical case of java.lang.StackOverflowError... The method is recursively calling itself with no exit in doubleValue(), floatValue(), etc.

    public class Rational extends Number implements Comparable<Rational> {
        private int num;
        private int denom;

        public Rational(int num, int denom) {
            this.num = num;
            this.denom = denom;

        public int compareTo(Rational r) {
            if ((num / denom) - (r.num / r.denom) > 0) {
                return +1;
            } else if ((num / denom) - (r.num / r.denom) < 0) {
                return -1;
            return 0;

        public Rational add(Rational r) {
            return new Rational(num + r.num, denom + r.denom);

        public Rational sub(Rational r) {
            return new Rational(num - r.num, denom - r.denom);

        public Rational mul(Rational r) {
            return new Rational(num * r.num, denom * r.denom);

        public Rational div(Rational r) {
            return new Rational(num * r.denom, denom * r.num);

        public int gcd(Rational r) {
            int i = 1;
            while (i != 0) {
                i = denom % r.denom;
                denom = r.denom;
                r.denom = i;
            return denom;

        public String toString() {
            String a = num + "/" + denom;
            return a;

        public double doubleValue() {
            return (double) doubleValue();

        public float floatValue() {
            return (float) floatValue();

        public int intValue() {
            return (int) intValue();

        public long longValue() {
            return (long) longValue();

    public class Main {

        public static void main(String[] args) {

            Rational a = new Rational(2, 4);
            Rational b = new Rational(2, 6);

            System.out.println(a + " + " + b + " = " + a.add(b));
            System.out.println(a + " - " + b + " = " + a.sub(b));
            System.out.println(a + " * " + b + " = " + a.mul(b));
            System.out.println(a + " / " + b + " = " + a.div(b));

            Rational[] arr = {new Rational(7, 1), new Rational(6, 1),
                    new Rational(5, 1), new Rational(4, 1),
                    new Rational(3, 1), new Rational(2, 1),
                    new Rational(1, 1), new Rational(1, 2),
                    new Rational(1, 3), new Rational(1, 4),
                    new Rational(1, 5), new Rational(1, 6),
                    new Rational(1, 7), new Rational(1, 8),
                    new Rational(1, 9), new Rational(0, 1)};


            for (int i = 0; i < arr.length - 1; ++i) {
                if (arr[i].compareTo(arr[i + 1]) > 0) {

            Number n = new Rational(3, 2);


        public static <T extends Comparable<? super T>> void selectSort(T[] array) {

            T temp;
            int mini;

            for (int i = 0; i < array.length - 1; ++i) {

                mini = i;

                for (int j = i + 1; j < array.length; ++j) {
                    if (array[j].compareTo(array[mini]) < 0) {
                        mini = j;

                if (i != mini) {
                    temp = array[i];
                    array[i] = array[mini];
                    array[mini] = temp;


    2/4 + 2/6 = 4/10
    Exception in thread "main" java.lang.StackOverflowError
    2/4 - 2/6 = 0/-2
        at com.xetrasu.Rational.doubleValue(
    2/4 * 2/6 = 4/24
        at com.xetrasu.Rational.doubleValue(
    2/4 / 2/6 = 12/8
        at com.xetrasu.Rational.doubleValue(
        at com.xetrasu.Rational.doubleValue(
        at com.xetrasu.Rational.doubleValue(
        at com.xetrasu.Rational.doubleValue(
        at com.xetrasu.Rational.doubleValue(

Here is the source code of StackOverflowError in OpenJDK 7

Custom thread pool in Java 8 parallel stream

Alternatively to the trick of triggering the parallel computation inside your own forkJoinPool you can also pass that pool to the CompletableFuture.supplyAsync method like in:

ForkJoinPool forkJoinPool = new ForkJoinPool(2);
CompletableFuture<List<Integer>> primes = CompletableFuture.supplyAsync(() ->
    //parallel task here, for example
    range(1, 1_000_000).parallel().filter(PrimesPrint::isPrime).collect(toList()), 

Capture characters from standard input without waiting for enter to be pressed

ncurses provides a nice way to do this! Also this is my very first post (that I can remember), so any comments at all are welcome. I will appreciate useful ones, but all are welcome!

to compile: g++ -std=c++11 -pthread -lncurses .cpp -o

#include <iostream>
#include <ncurses.h>
#include <future>

char get_keyboard_input();

int main(int argc, char *argv[])

    auto f = std::async(std::launch::async, get_keyboard_input);
    while (f.wait_for(std::chrono::milliseconds(20)) != std::future_status::ready)
        // do some work

    std::cout << "returned: " << f.get() << std::endl;
    return 0;

char get_keyboard_input()
    char input = '0';
    while(input != 'q')
        input = getch();
    return input;

How to check if a column exists in Pandas

To check if one or more columns all exist, you can use set.issubset, as in:

if set(['A','C']).issubset(df.columns):
   df['sum'] = df['A'] + df['C']                

As @brianpck points out in a comment, set([]) can alternatively be constructed with curly braces,

if {'A', 'C'}.issubset(df.columns):

See this question for a discussion of the curly-braces syntax.

Or, you can use a list comprehension, as in:

if all([item in df.columns for item in ['A','C']]):

Pro JavaScript programmer interview questions (with answers)

Ask them how they ensure their pages continue to be usable when the user has JavaScript turned off or JavaScript isn't available.

There's no One True Answer, but you're fishing for an answer talking about some strategies for Progressive Enhancement.

Progressive Enhancement consists of the following core principles:

  • basic content should be accessible to all browsers
  • basic functionality should be accessible to all browsers
  • sparse, semantic markup contains all content
  • enhanced layout is provided by externally linked CSS
  • enhanced behavior is provided by [[Unobtrusive JavaScript|unobtrusive]], externally linked JavaScript
  • end user browser preferences are respected

Java compile error: "reached end of file while parsing }"

It happens when you don't properly close the code block:

if (condition){
  // your code goes here*
  { // This doesn't close the code block

Correct way:

if (condition){
  // your code goes here
} // Close the code block

CSS two divs next to each other

As everyone has pointed out, you'll do this by setting a float:right; on the RHS content and a negative margin on the LHS.

However.. if you don't use a float: left; on the LHS (as Mohit does) then you'll get a stepping effect because the LHS div is still going to consume the margin'd space in layout.

However.. the LHS float will shrink-wrap the content, so you'll need to insert a defined width childnode if that's not acceptable, at which point you may as well have defined the width on the parent.

However.. as David points out you can change the read-order of the markup to avoid the LHS float requirement, but that's has readability and possibly accessibility issues.

However.. this problem can be solved with floats given some additional markup

(caveat: I don't approve of the .clearing div at that example, see here for details)

All things considered, I think most of us wish there was a non-greedy width:remaining in CSS3...

What does request.getParameter return?

String onevalue;   

ExecuteReader requires an open and available Connection. The connection's current state is Connecting

I caught this error a few days ago.

IN my case it was because I was using a Transaction on a Singleton.

.Net does not work well with Singleton as stated above.

My solution was this:

public class DbHelper : DbHelperCore
    public DbHelper()
        Connection = null;
        Transaction = null;

    public static DbHelper instance
            if (HttpContext.Current is null)
                return new DbHelper();
            else if (HttpContext.Current.Items["dbh"] == null)
                HttpContext.Current.Items["dbh"] = new DbHelper();

            return (DbHelper)HttpContext.Current.Items["dbh"];

    public override void BeginTransaction()
        Connection = new SqlConnection(Entity.Connection.getCon);
        if (Connection.State == System.Data.ConnectionState.Closed)
        Transaction = Connection.BeginTransaction();

I used HttpContext.Current.Items for my instance. This class DbHelper and DbHelperCore is my own class

Access properties file programmatically with Spring?

Create a class like below

    package com.tmghealth.common.util;

    import java.util.Properties;

    import org.springframework.beans.BeansException;

    import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

    import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;

    import org.springframework.context.annotation.Configuration;

    import org.springframework.context.annotation.PropertySource;

    import org.springframework.stereotype.Component;

    @PropertySource(value = { "classpath:/spring/" })
    public class PropertiesReader extends PropertyPlaceholderConfigurer {

        protected void processProperties(
                ConfigurableListableBeanFactory beanFactory, Properties props)
                throws BeansException {
            super.processProperties(beanFactory, props);



Then wherever you want to access a property use

        private Environment environment;
    and getters and setters then access using 

                    + ".letter.fdi.letterdetails.restServiceUrl");

-- write getters and setters in the accessor class

    public Environment getEnvironment() {
            return environment;
        }`enter code here`

        public void setEnvironment(Environment environment) {
            this.environment = environment;

How do I obtain the frequencies of each value in an FFT?

The first bin in the FFT is DC (0 Hz), the second bin is Fs / N, where Fs is the sample rate and N is the size of the FFT. The next bin is 2 * Fs / N. To express this in general terms, the nth bin is n * Fs / N.

So if your sample rate, Fs is say 44.1 kHz and your FFT size, N is 1024, then the FFT output bins are at:

  0:   0 * 44100 / 1024 =     0.0 Hz
  1:   1 * 44100 / 1024 =    43.1 Hz
  2:   2 * 44100 / 1024 =    86.1 Hz
  3:   3 * 44100 / 1024 =   129.2 Hz
  4: ...
  5: ...
511: 511 * 44100 / 1024 = 22006.9 Hz

Note that for a real input signal (imaginary parts all zero) the second half of the FFT (bins from N / 2 + 1 to N - 1) contain no useful additional information (they have complex conjugate symmetry with the first N / 2 - 1 bins). The last useful bin (for practical aplications) is at N / 2 - 1, which corresponds to 22006.9 Hz in the above example. The bin at N / 2 represents energy at the Nyquist frequency, i.e. Fs / 2 ( = 22050 Hz in this example), but this is in general not of any practical use, since anti-aliasing filters will typically attenuate any signals at and above Fs / 2.

Node.js/Express routing with get params

Your route isn't ok, it should be like this (with ':')

app.get('/documents/:format/:type', function (req, res) {
   var format = req.params.format,
       type = req.params.type;

Also you cannot interchange parameter order unfortunately. For more information on req.params (and req.query) check out the api reference here.

Difference between text and varchar (character varying)

On PostgreSQL manual

There is no performance difference among these three types, apart from increased storage space when using the blank-padded type, and a few extra CPU cycles to check the length when storing into a length-constrained column. While character(n) has performance advantages in some other database systems, there is no such advantage in PostgreSQL; in fact character(n) is usually the slowest of the three because of its additional storage costs. In most situations text or character varying should be used instead.

I usually use text


Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

in this case, I use space for APP_NAME key in .env file.

and have below error :

The environment file is invalid!
Failed to parse dotenv file due to unexpected whitespace. Failed at [my name].
Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

Don't use space in APP_NAME key !!

Running a command in a new Mac OS X Terminal window

Here's yet another take on it (also using AppleScript):

function newincmd() { 
   declare args 
   # escape single & double quotes 
   printf "%s" "${args}" | /usr/bin/pbcopy 
   #printf "%q" "${args}" | /usr/bin/pbcopy 
   /usr/bin/open -a Terminal 
   /usr/bin/osascript -e 'tell application "Terminal" to do script with command "/usr/bin/clear; eval \"$(/usr/bin/pbpaste)\""' 
   return 0 

newincmd ls 

newincmd echo "hello \" world" 
newincmd echo $'hello \' world' 


Difference between Select Unique and Select Distinct

  1. Unique was the old syntax while Distinct is the new syntax,which is now the Standard sql.
  2. Unique creates a constraint that all values to be inserted must be different from the others. An error can be witnessed if one tries to enter a duplicate value. Distinct results in the removal of the duplicate rows while retrieving data.
  3. Example: SELECT DISTINCT names FROM student ;

    CREATE TABLE Persons ( Id varchar NOT NULL UNIQUE, Name varchar(20) );

Convert timestamp to string

try this

SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
String string  = dateFormat.format(new Date());

you can create any format see this

How to remove the first character of string in PHP?

Exec time for the 3 answers :

Remove the first letter by replacing the case

$str = "hello";
$str[0] = "";
// $str[0] = false;
// $str[0] = null;
// replaced by ?, but ok for echo

Exec time for 1.000.000 tests : 0.39602184295654 sec

Remove the first letter with substr()

$str = "hello";
$str = substr($str, 1);

Exec time for 1.000.000 tests : 5.153294801712 sec

Remove the first letter with ltrim()

$str = "hello";
$str= ltrim ($str,'h');

Exec time for 1.000.000 tests : 5.2393000125885 sec

Remove the first letter with preg_replace()

$str = "hello";
$str = preg_replace('/^./', '', $str);

Exec time for 1.000.000 tests : 6.8543920516968 sec

How do I fix the "You don't have write permissions into the /usr/bin directory" error when installing Rails?

Using the -n /usr/local/bin flag does work, BUT I had to come back to this page every time I wanted to update a package again. So I figured out a permanent fix for this.

For those interested in fixing this permanently:

Create a ~/.gemrc file

vim .gemrc

With the following content:

   - ~/.gem/ruby
install: -n /usr/local/bin

Now you can run your command normally without the -n flag.


combining two data frames of different lengths

Refering to Andrie's answer, suggesting to use plyr::rbind.fill(): Combined with t() you have something like cbind.fill() (which is not part of plyr) that will construct your data frame with consideration of identical case numbers.

PHP date time greater than today

You are not comparing dates. You are comparing strings. In the world of string comparisons, 09/17/2015 > 01/02/2016 because 09 > 01. You need to either put your date in a comparable string format or compare DateTime objects which are comparable.

 $date_now = date("Y-m-d"); // this format is string comparable

if ($date_now > '2016-01-02') {
    echo 'greater than';
    echo 'Less than';



 $date_now = new DateTime();
 $date2    = new DateTime("01/02/2016");

if ($date_now > $date2) {
    echo 'greater than';
    echo 'Less than';


Why use the params keyword?

One more important thing needs to be highlighted. It's better to use params because it is better for performance. When you call a method with params argument and passed to it nothing:

public void ExampleMethod(params string[] args)
// do some stuff



Then a new versions of the .Net Framework do this (from .Net Framework 4.6):


This Array.Empty object can be reused by framework later, so there are no needs to do redundant allocations. These allocations will occur when you call this method like this:

 ExampleMethod(new string[] {});

RuntimeWarning: DateTimeField received a naive datetime

make sure has USE_TZ = True

In your python file:

from django.utils import timezone # use its value in model field

Calculate distance in meters when you know longitude and latitude in java

Based on another question on stackoverflow, I got this code.. This calculates the result in meters, not in miles :)

 public static float distFrom(float lat1, float lng1, float lat2, float lng2) {
    double earthRadius = 6371000; //meters
    double dLat = Math.toRadians(lat2-lat1);
    double dLng = Math.toRadians(lng2-lng1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
               Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
               Math.sin(dLng/2) * Math.sin(dLng/2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    float dist = (float) (earthRadius * c);

    return dist;

Setting new value for an attribute using jQuery

It is working you have to check attr after assigning value


$('#amount').attr( 'datamin','1000');

alert($('#amount').attr( 'datamin'));?

Excel - Using COUNTIF/COUNTIFS across multiple sheets/same column

I am trying to avoid using VBA. But if has to be, then it has to be:)

There is quite simple UDF for you:

Function myCountIf(rng As Range, criteria) As Long
    Dim ws As Worksheet

    For Each ws In ThisWorkbook.Worksheets
        myCountIf = myCountIf + WorksheetFunction.CountIf(ws.Range(rng.Address), criteria)
    Next ws
End Function

and call it like this: =myCountIf(I:I,A13)

P.S. if you'd like to exclude some sheets, you can add If statement:

Function myCountIf(rng As Range, criteria) As Long
    Dim ws As Worksheet

    For Each ws In ThisWorkbook.Worksheets
        If <> "Sheet1" And <> "Sheet2" Then
            myCountIf = myCountIf + WorksheetFunction.CountIf(ws.Range(rng.Address), criteria)
        End If
    Next ws
End Function


I have four "reference" sheets that I need to exclude from being scanned/searched. They are currently the last four in the workbook

Function myCountIf(rng As Range, criteria) As Long
    Dim i As Integer

    For i = 1 To ThisWorkbook.Worksheets.Count - 4
        myCountIf = myCountIf + WorksheetFunction.CountIf(ThisWorkbook.Worksheets(i).Range(rng.Address), criteria)
    Next i
End Function

Using headers with the Python requests library's get method

According to the API, the headers can all be passed in using requests.get:

import requests
r=requests.get("", headers={"content-type":"text"})

Displaying standard DataTables in MVC

This is not "wrong" at all, it's just not what the cool guys typically do with MVC. As an aside, I wish some of the early demos of ASP.NET MVC didn't try to cram in Linq-to-Sql at the same time. It's pretty awesome and well suited for MVC, sure, but it's not required. There is nothing about MVC that prevents you from using ADO.NET. For example:

Controller action:

public ActionResult Index()
    ViewData["Message"] = "Welcome to ASP.NET MVC!";

    DataTable dt = new DataTable("MyTable");
    dt.Columns.Add(new DataColumn("Col1", typeof(string)));
    dt.Columns.Add(new DataColumn("Col2", typeof(string)));
    dt.Columns.Add(new DataColumn("Col3", typeof(string)));

    for (int i = 0; i < 3; i++)
        DataRow row = dt.NewRow();
        row["Col1"] = "col 1, row " + i;
        row["Col2"] = "col 2, row " + i;
        row["Col3"] = "col 3, row " + i;

    return View(dt); //passing the DataTable as my Model

View: (w/ Model strongly typed as System.Data.DataTable)

<table border="1">
            <%foreach (System.Data.DataColumn col in Model.Columns) { %>
                <th><%=col.Caption %></th>
            <%} %>
    <% foreach(System.Data.DataRow row in Model.Rows) { %>
            <% foreach (var cell in row.ItemArray) {%>
                <td><%=cell.ToString() %></td>
            <%} %>
    <%} %>         

Now, I'm violating a whole lot of principles and "best-practices" of ASP.NET MVC here, so please understand this is just a simple demonstration. The code creating the DataTable should reside somewhere outside of the controller, and the code in the View might be better isolated to a partial, or html helper, to name a few ways you should do things.

You absolutely are supposed to pass objects to the View, if the view is supposed to present them. (Separation of concerns dictates the view shouldn't be responsible for creating them.) In this case I passed the DataTable as the actual view Model, but you could just as well have put it in ViewData collection. Alternatively you might make a specific IndexViewModel class that contains the DataTable and other objects, such as the welcome message.

I hope this helps!

How to do a PUT request with curl?

Quick Answer:

In a single line, the curl command would be:

a) If sending form data:

curl -X PUT -H "Content-Type: multipart/form-data;" -F "key1=val1" "YOUR_URI"

b) If sending raw data as json:

curl -X PUT -H "Content-Type: application/json" -d '{"key1":"value"}' "YOUR_URI"

c) If sending a file with a POST request:

curl -X POST "YOUR_URI" -F 'file=@/file-path.csv'

Alternative solution:

You can use the POSTMAN app from Chrome Store to get the equivalent cURL request. This is especially useful when writing more complicated requests.

For the request with other formats or for different clients like java, PHP, you can check out POSTMAN/comment below.

POSTMAN to get the request code

Simplest way to throw an error/exception with a custom message in Swift 2?

I like @Alexander-Borisenko's answer, but the localized description was not returned when caught as an Error. It seems that you need to use LocalizedError instead:

struct RuntimeError: LocalizedError
    let message: String

    init(_ message: String)
        self.message = message

    public var errorDescription: String?
        return message

See this answer for more details.

App not setup: This app is still in development mode


In Settings -> Basic -> Contact Email. (Give your/any email)

STEP 2: in 'App Review' Tab : change

Do you want to make this app and all its live features available to the general public? Yes

And cheers ..

Retrieving JSON Object Literal from HttpServletRequest

Converting the retreived data from the request object to json object is as below using google-gson

Gson gson = new Gson();
ABCClass c1 = gson.fromJson(data, ABCClass.class);

//ABC class is a class whose strcuture matches to the data variable retrieved

Better way to represent array in java properties file

I have custom loading. Properties must be defined as:


Custom loading:

/** Return array from properties file. Array must be defined as "key.0=value0", "key.1=value1", ... */
public List<String> getSystemStringProperties(String key) {

    // result list
    List<String> result = new LinkedList<>();

    // defining variable for assignment in loop condition part
    String value;

    // next value loading defined in condition part
    for(int i = 0; (value = YOUR_PROPERTY_OBJECT.getProperty(key + "." + i)) != null; i++) {

    // return
    return result;

Changing the default title of confirm() in JavaScript?

Don't use the confirm() dialog then... easy to use a custom dialog from prototype/scriptaculous, YUI, jQuery ... there's plenty out there.

Laravel - Eloquent "Has", "With", "WhereHas" - What do they mean?


with() is for eager loading. That basically means, along the main model, Laravel will preload the relationship(s) you specify. This is especially helpful if you have a collection of models and you want to load a relation for all of them. Because with eager loading you run only one additional DB query instead of one for every model in the collection.


User > hasMany > Post

$users = User::with('posts')->get();
foreach($users as $user){
    $users->posts; // posts is already loaded and no additional DB query is run


has() is to filter the selecting model based on a relationship. So it acts very similarly to a normal WHERE condition. If you just use has('relation') that means you only want to get the models that have at least one related model in this relation.


User > hasMany > Post

$users = User::has('posts')->get();
// only users that have at least one post are contained in the collection


whereHas() works basically the same as has() but allows you to specify additional filters for the related model to check.


User > hasMany > Post

$users = User::whereHas('posts', function($q){
    $q->where('created_at', '>=', '2015-01-01 00:00:00');
// only users that have posts from 2015 on forward are returned

Can you force a React component to rerender without calling setState?

There are a few ways to rerender your component:

The simplest solution is to use forceUpdate() method:


One more solution is to create not used key in the state(nonUsedKey) and call setState function with update of this nonUsedKey:

this.setState({ nonUsedKey: } );

Or rewrite all current state:


Props changing also provides component rerender.

How can I remove the outline around hyperlinks images?

This is the latest one that works on Google Chrome

:link:focus, :visited:focus {outline: none;}

update to python 3.7 using anaconda

This can be installed via conda with the command conda install -c anaconda python=3.7 as per

Though not all packages support 3.7 yet, running conda update --all may resolve some dependency failures.

why numpy.ndarray is object is not callable in my simple for python loop

Avoid the for loopfor XY in xy: Instead read up how the numpy arrays are indexed and handled.

Numpy Indexing

Also try and avoid .txt files if you are dealing with matrices. Try to use .csv or .npy files, and use Pandas dataframework to load them just for clarity.

How to attach a process in gdb

The first argument should be the path to the executable program. So

gdb progname 12271

Convert a string to integer with decimal in Python

You could use:

s = '23.245678'
i = int(float(s))

Aligning a float:left div to center?

.contentWrapper {
    float: left;
    clear: both;
    margin-left: 10%;
    margin-right: 10%;

.repeater {
    height: 9em;
    width: 9em;
    float: left;
    margin: 0.2em;
    position: relative;
    text-align: center;
    cursor: pointer;

What is the difference between "px", "dip", "dp" and "sp"?

dp is dip. Use it for everything (margin, padding, etc.).

Use sp for {text-size} only.

To get the same size on different screen densities, Android translates these units into pixels at runtime, so there is no tricky math for you to do.

See the difference between px, dp and sp on different screen sizes.

Enter image description here

Source: Android Programming: The Big Nerd Ranch Guide

How to resolve Error : Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation

For Vb.Net Framework 4.0, U can use:

Alert("your message here", Boolean)

The Boolean here can be True or False. True If you want to close the window right after, False If you want to keep the window open.

What is the best way to merge mp3 files?

What I really wanted was a GUI to reorder them and output them as one file

Playlist Producer does exactly that, decoding and reencoding them into a combined MP3. It's designed for creating mix tapes or simple podcasts, but you might find it useful.

(Disclosure: I wrote the software, and I profit if you buy the Pro Edition. The Lite edition is a free version with a few limitations).

R solve:system is exactly singular

Using solve with a single parameter is a request to invert a matrix. The error message is telling you that your matrix is singular and cannot be inverted.

The APK file does not exist on disk

I tried all of these things and none of them worked. I ended up having to do a couple of these things are the same time. Very frustrating that it took this much time.

The problem I had was related to running my unit tests following the upgrade to AS 3.1.

Here is what I did... 1.) Run / Edit Configurations / Select Tests.... 2.) Add options to "Gradle-aware Make" 3.) Select check box "Skip installation if ADK has not changed" on Misc tab

Good luck.

What is an abstract class in PHP?

  • Abstract Class contains only declare the method's signature, they can't define the implementation.
  • Abstraction class are defined using the keyword abstract .
  • Abstract Class is not possible to implement multiple inheritance.
  • Latest version of PHP 5 has introduces abstract classes and methods.
  • Classes defined as abstract , we are unable to create the object ( may not instantiated )

Java get last element of a collection

To avoid some of the problems mentioned above (not robust for nulls etc etc), to get first and last element in a list an approach could be

import java.util.List;

public static final <A> A getLastElement(List<A> list) {
    return list != null ? getElement(list, list.size() - 1) : null;

public static final <A> A getFirstElement(List<A> list) {
    return list != null ? getElement(list, 0) : null;

private static final <A> A getElement(List<A> list, int pointer) {
    A res = null;
    if (list.size() > 0) {
        res = list.get(pointer);            
    return res;

The convention adopted is that the first/last element of an empty list is null...

Difference between Divide and Conquer Algo and Dynamic Programming

Divide and Conquer

  • In this problem is solved in following three steps: 1. Divide - Dividing into number of sub-problems 2. Conquer - Conquering by solving sub-problems recursively 3. Combine - Combining sub-problem solutions to get original problem's solution
  • Recursive approach
  • Top Down technique
  • Example: Merge Sort

Dynamic Programming

  • In this the problem is solved in following steps: 1. Defining structure of optimal solution 2. Defines value of optimal solutions repeatedly. 3. Obtaining values of optimal solution in bottom-up fashion 4. Getting final optimal solution from obtained values
  • Non-Recursive
  • Bottom Up Technique
  • Example: Strassen's Matrix Multiplication

Append TimeStamp to a File Name

You can use DateTime.ToString Method (String)


or string.Format

string.Format("{0:yyyy-MM-dd_HH-mm-ss-fff}", DateTime.Now);

or Interpolated Strings


There are following custom format specifiers y (year), M (month), d (day), h (hour 12), H (hour 24), m (minute), s (second), f (second fraction), F (second fraction, trailing zeroes are trimmed), t (P.M or A.M) and z (time zone).

With Extension Method


string result = "myfile.txt".AppendTimeStamp();

Extension method

public static class MyExtensions
    public static string AppendTimeStamp(this string fileName)
        return string.Concat(

How to define a variable in a Dockerfile?

You can use ARG variable defaultValue and during the run command you can even update this value using --build-arg variable=value. To use these variables in the docker file you can refer them as $variable in run command.

Note: These variables would be available for Linux commands like RUN echo $variable and they wouldn't persist in the image.

iOS 7 - Failing to instantiate default view controller

None of the above solved the issue for me. In my case it was not also setting the correct application scene manifest.

I had to change LoginScreen used to be Main

enter image description here

How do I get Maven to use the correct repositories?

Basically, all Maven is telling you is that certain dependencies in your project are not available in the central maven repository. The default is to look in your local .m2 folder (local repository), and then any configured repositories in your POM, and then the central maven repository. Look at the repositories section of the Maven reference.

The problem is that the project that was checked in didn't configure the POM in such a way that all the dependencies could be found and the project could be built from scratch.

Git commit date

You can use the git show command.

To get the last commit date from git repository in a long(Unix epoch timestamp):

  • Command: git show -s --format=%ct
  • Result: 1605103148

Note: You can visit the git-show documentation to get a more detailed description of the options.

The SQL OVER() clause - when and why is it useful?

So in simple words: Over clause can be used to select non aggregated values along with Aggregated ones.

Partition BY, ORDER BY inside, and ROWS or RANGE are part of OVER() by clause.

partition by is used to partition data and then perform these window, aggregated functions, and if we don't have partition by the then entire result set is considered as a single partition.

OVER clause can be used with Ranking Functions(Rank, Row_Number, Dense_Rank..), Aggregate Functions like (AVG, Max, Min, SUM...etc) and Analytics Functions like (First_Value, Last_Value, and few others).

Let's See basic syntax of OVER clause

OVER (   
       [ <PARTITION BY clause> ]  
       [ <ORDER BY clause> ]   
       [ <ROW or RANGE clause> ]  

PARTITION BY: It is used to partition data and perform operations on groups with the same data.

ORDER BY: It is used to define the logical order of data in Partitions. When we don't specify Partition, entire resultset is considered as a single partition

: This can be used to specify what rows are supposed to be considered in a partition when performing the operation.

Let's take an example:

Here is my dataset:

Id          Name                                               Gender     Salary
----------- -------------------------------------------------- ---------- -----------
1           Mark                                               Male       5000
2           John                                               Male       4500
3           Pavan                                              Male       5000
4           Pam                                                Female     5500
5           Sara                                               Female     4000
6           Aradhya                                            Female     3500
7           Tom                                                Male       5500
8           Mary                                               Female     5000
9           Ben                                                Male       6500
10          Jodi                                               Female     7000
11          Tom                                                Male       5500
12          Ron                                                Male       5000

So let me execute different scenarios and see how data is impacted and I'll come from difficult syntax to simple one

Select *,SUM(salary) Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        32000
1           Mark                                               Male       5000        32000
8           Mary                                               Female     5000        32000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        48500
7           Tom                                                Male       5500        48500
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

Just observe the sum_sal part. Here I am using order by Salary and using "RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW". In this case, we are not using partition so entire data will be treated as one partition and we are ordering on salary. And the important thing here is UNBOUNDED PRECEDING AND CURRENT ROW. This means when we are calculating the sum, from starting row to the current row for each row. But if we see rows with salary 5000 and name="Pavan", ideally it should be 17000 and for salary=5000 and name=Mark, it should be 22000. But as we are using RANGE and in this case, if it finds any similar elements then it considers them as the same logical group and performs an operation on them and assigns value to each item in that group. That is the reason why we have the same value for salary=5000. The engine went up to salary=5000 and Name=Ron and calculated sum and then assigned it to all salary=5000.

Select *,SUM(salary) Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

   Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        17000
1           Mark                                               Male       5000        22000
8           Mary                                               Female     5000        27000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        37500
7           Tom                                                Male       5500        43000
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

So with ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW The difference is for same value items instead of grouping them together, It calculates SUM from starting row to current row and it doesn't treat items with same value differently like RANGE

Select *,SUM(salary) Over(order by salary) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        32000
1           Mark                                               Male       5000        32000
8           Mary                                               Female     5000        32000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        48500
7           Tom                                                Male       5500        48500
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

These results are the same as

Select *, SUM(salary) Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

That is because Over(order by salary) is just a short cut of Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) So wherever we simply specify Order by without ROWS or RANGE it is taking RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW as default.

Note: This is applicable only to Functions that actually accept RANGE/ROW. For example, ROW_NUMBER and few others don't accept RANGE/ROW and in that case, this doesn't come into the picture.

Till now we saw that Over clause with an order by is taking Range/ROWS and syntax looks something like this RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW And it is actually calculating up to the current row from the first row. But what If it wants to calculate values for the entire partition of data and have it for each column (that is from 1st row to last row). Here is the query for that

Select *,sum(salary) Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
1           Mark                                               Male       5000        62000
2           John                                               Male       4500        62000
3           Pavan                                              Male       5000        62000
4           Pam                                                Female     5500        62000
5           Sara                                               Female     4000        62000
6           Aradhya                                            Female     3500        62000
7           Tom                                                Male       5500        62000
8           Mary                                               Female     5000        62000
9           Ben                                                Male       6500        62000
10          Jodi                                               Female     7000        62000
11          Tom                                                Male       5500        62000
12          Ron                                                Male       5000        62000

Instead of CURRENT ROW, I am specifying UNBOUNDED FOLLOWING which instructs the engine to calculate till the last record of partition for each row.

Now coming to your point on what is OVER() with empty braces?

It is just a short cut for Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)

Here we are indirectly specifying to treat all my resultset as a single partition and then perform calculations from the first record to the last record of each partition.

Select *,Sum(salary) Over() as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
1           Mark                                               Male       5000        62000
2           John                                               Male       4500        62000
3           Pavan                                              Male       5000        62000
4           Pam                                                Female     5500        62000
5           Sara                                               Female     4000        62000
6           Aradhya                                            Female     3500        62000
7           Tom                                                Male       5500        62000
8           Mary                                               Female     5000        62000
9           Ben                                                Male       6500        62000
10          Jodi                                               Female     7000        62000
11          Tom                                                Male       5500        62000
12          Ron                                                Male       5000        62000

I did create a video on this and if you are interested you can visit it.

Thanks, Pavan Kumar Aryasomayajulu HTTP://

Process to convert simple Python script into Windows executable

1) Get py2exe from here, according to your Python version.

2) Make a file called "" in the same folder as the script you want to convert, having the following code:

from distutils.core import setup
import py2exe
setup(console=['']) #change 'myscript' to your script

3) Go to command prompt, navigate to that folder, and type:

python py2exe

4) It will generate a "dist" folder in the same folder as the script. This folder contains the .exe file.

How to get the selected index of a RadioGroup in Android



  btnDisplay.setOnClickListener(new View.OnClickListener() {
     public void onClick(View v) {
        int selectedId=radioSexGroup.getCheckedRadioButtonId();

How to implement class constants?

Either use readOnly modifier with the constant one needs to declare or one might declare a constant outside the class and use it specifically only in the required class using get operator.

How can I change the remote/target repository URL on Windows?

Take a look in .git/config and make the changes you need.

Alternatively you could use

git remote rm [name of the url you sets on adding]


git remote add [name] [URL]

Or just

git remote set-url [URL]

Before you do anything wrong, double check with

git help remote

Binding Button click to a method

I do this all the time. Here's a look at an example and how you would implement it.

Change your XAML to use the Command property of the button instead of the Click event. I am using the name SaveCommand since it is easier to follow then something named Command.

<Button Command="{Binding Path=SaveCommand}" />

Your CustomClass that the Button is bound to now needs to have a property called SaveCommand of type ICommand. It needs to point to the method on the CustomClass that you want to run when the command is executed.

public MyCustomClass
    private ICommand _saveCommand;

    public ICommand SaveCommand
            if (_saveCommand == null)
                _saveCommand = new RelayCommand(
                    param => this.SaveObject(), 
                    param => this.CanSave()
            return _saveCommand;

    private bool CanSave()
        // Verify command can be executed here

    private void SaveObject()
        // Save command execution logic

The above code uses a RelayCommand which accepts two parameters: the method to execute, and a true/false value of if the command can execute or not. The RelayCommand class is a separate .cs file with the code shown below. I got it from Josh Smith :)

/// <summary>
/// A command whose sole purpose is to 
/// relay its functionality to other
/// objects by invoking delegates. The
/// default return value for the CanExecute
/// method is 'true'.
/// </summary>
public class RelayCommand : ICommand
    #region Fields

    readonly Action<object> _execute;
    readonly Predicate<object> _canExecute;        

    #endregion // Fields

    #region Constructors

    /// <summary>
    /// Creates a new command that can always execute.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    public RelayCommand(Action<object> execute)
        : this(execute, null)

    /// <summary>
    /// Creates a new command.
    /// </summary>
    /// <param name="execute">The execution logic.</param>
    /// <param name="canExecute">The execution status logic.</param>
    public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        if (execute == null)
            throw new ArgumentNullException("execute");

        _execute = execute;
        _canExecute = canExecute;           

    #endregion // Constructors

    #region ICommand Members

    public bool CanExecute(object parameters)
        return _canExecute == null ? true : _canExecute(parameters);

    public event EventHandler CanExecuteChanged
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }

    public void Execute(object parameters)

    #endregion // ICommand Members

Convert an enum to List<string>

I want to add another solution: In my case, I need to use a Enum group in a drop down button list items. So they might have space, i.e. more user friendly descriptions needed:

  public enum CancelReasonsEnum
    [Description("In rush")]
    [Description("Need more coffee")]
    [Description("Call me back in 5 minutes!")]

In a helper class (HelperMethods) I created the following method:

 public static List<string> GetListOfDescription<T>() where T : struct
        Type t = typeof(T);
        return !t.IsEnum ? null : Enum.GetValues(t).Cast<Enum>().Select(x => x.GetDescription()).ToList();

When you call this helper you will get the list of item descriptions.

 List<string> items = HelperMethods.GetListOfDescription<CancelReasonEnum>();

ADDITION: In any case, if you want to implement this method you need :GetDescription extension for enum. This is what I use.

 public static string GetDescription(this Enum value)
        Type type = value.GetType();
        string name = Enum.GetName(type, value);
        if (name != null)
            FieldInfo field = type.GetField(name);
            if (field != null)
                DescriptionAttribute attr =Attribute.GetCustomAttribute(field,typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attr != null)
                    return attr.Description;
        return null;
        /* how to use
            MyEnum x = MyEnum.NeedMoreCoffee;
            string description = x.GetDescription();


How do I make CMake output into a 'bin' dir?

Regardless of whether I define this in the main CMakeLists.txt or in the individual ones, it still assumes I want all the libs and bins off the main path, which is the least useful assumption of all.

Replace non-numeric with empty string

I'm sure there's a more efficient way to do it, but I would probably do this:

string getTenDigitNumber(string input)
    StringBuilder sb = new StringBuilder();
    for(int i - 0; i < input.Length; i++)
        int junk;
        if(int.TryParse(input[i], ref junk))
    return sb.ToString();

How can I get Eclipse to show .* files?

If you're using Eclipse PDT, this is done by opening up the PHP explorer view, then clicking the upside-down triangle in the top-right of that window. A context window appears, and the filters option is available there. Clicking the Filters menu option opens a new window, where .* files can be unchecked, thus allowing the editing of .htaccess files.

I searched forever for this, so I'm sorta answering my own question here. I'm sure someone else will have the same problem too, so I hope this helps someone else as well.

How to create a simple checkbox in iOS?

Yeah, no checkbox for you in iOS (-:

Here, this is what I did to create a checkbox:

UIButton *checkbox;
BOOL checkBoxSelected;
checkbox = [[UIButton alloc] initWithFrame:CGRectMake(x,y,20,20)];
// 20x20 is the size of the checkbox that you want
// create 2 images sizes 20x20 , one empty square and
// another of the same square with the checkmark in it
// Create 2 UIImages with these new images, then:

[checkbox setBackgroundImage:[UIImage imageNamed:@"notselectedcheckbox.png"]
[checkbox setBackgroundImage:[UIImage imageNamed:@"selectedcheckbox.png"]
[checkbox setBackgroundImage:[UIImage imageNamed:@"selectedcheckbox.png"]
[checkbox addTarget:(nullable id) action:(nonnull SEL) forControlEvents:(UIControlEvents)];
[self.view addSubview:checkbox];

Now in the target method do the following:

    checkBoxSelected = !checkBoxSelected; /* Toggle */
    [checkbox setSelected:checkBoxSelected];

That's it!

Cannot find runtime 'node' on PATH - Visual Studio Code and Node.js

first run below commands as super user sudo code . --user-data-dir='.' it will open the visual code studio import the folder of your project and set the launch.json as below

    "version": "0.2.0",
    "configurations": [
            "type": "node",
            "request": "launch",
            "name": "Launch Program",
            "program": "${workspaceFolder}/app/release/web.js",
            "outFiles": [
            "runtimeExecutable": "/root/.nvm/versions/node/v8.9.4/bin/node"

path of runtimeExecutable will be output of "which node" command.

Run the server in debug mode cheers

How to read HDF5 files in Python

you can use Pandas.

import pandas as pd

java.lang.OutOfMemoryError: Java heap space

  1. Upto my knowledge, Heap space is occupied by instance variables only. If this is correct, then why this error occurred after running fine for sometime as space for instance variables are alloted at the time of object creation.

That means you are creating more objects in your application over a period of time continuously. New objects will be stored in heap memory and that's the reason for growth in heap memory.

Heap not only contains instance variables. It will store all non-primitive data types ( Objects). These objects life time may be short (method block) or long (till the object is referenced in your application)

  1. Is there any way to increase the heap space?

Yes. Have a look at this oracle article for more details.

There are two parameters for setting the heap size:

-Xms:, which sets the initial and minimum heap size

-Xmx:, which sets the maximum heap size

  1. What changes should I made to my program so that It will grab less heap space?

It depends on your application.

  1. Set the maximum heap memory as per your application requirement

  2. Don't cause memory leaks in your application

  3. If you find memory leaks in your application, find the root cause with help of profiling tools like MAT, Visual VM , jconsole etc. Once you find the root cause, fix the leaks.

Important notes from oracle article

Cause: The detail message Java heap space indicates object could not be allocated in the Java heap. This error does not necessarily imply a memory leak.

Possible reasons:

  1. Improper configuration ( not allocating sufficiant memory)
  2. Application is unintentionally holding references to objects and this prevents the objects from being garbage collected
  3. Applications that make excessive use of finalizers. If a class has a finalize method, then objects of that type do not have their space reclaimed at garbage collection time. If the finalizer thread cannot keep up, with the finalization queue, then the Java heap could fill up and this type of OutOfMemoryError exception would be thrown.

On a different note, use better Garbage collection algorithms ( CMS or G1GC)

Have a look at this question for understanding G1GC

how to save and read array of array in NSUserdefaults in swift?

Just to add on to what @Zaph says in the comments.

I have the same problem as you, as to know, the array of String is not saved. Even though Apple bridges types such as String and NSString, I wasn't able to save an array of [String] neither of [AnyObject].

However an array of [NSString] works for me.

So your code could look like that :

var key = "keySave"

var array1: [NSString] = [NSString]()
array1.append("value 1")
array1.append("value 2")

var defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(array1, forKey: key)

if let testArray : AnyObject? = defaults.objectForKey(key) {
    var readArray : [NSString] = testArray! as [NSString]

Note that I created an array of NSString and not a dictionary. I didn't check if it works with a dictionary, but probably you will have to define the things as [NSString : NSString] to have it working.


Re-reading your question and your title, you are talking of array of array. I think that as long as you stay with NSString, an array of array will work. However, if you think my answer is irrelevant, just let me know in the comments and I will remove it.

Is JavaScript's "new" keyword considered harmful?

Javascript being dynamic language there a zillion ways to mess up where another language would stop you.

Avoiding a fundamental language feature such as new on the basis that you might mess up is a bit like removing your shiny new shoes before walking through a minefield just in case you might get your shoes muddy.

I use a convention where function names begin with a lower case letter and 'functions' that are actually class definitions begin with a upper case letter. The result is a really quite compelling visual clue that the 'syntax' is wrong:-

var o = MyClass();  // this is clearly wrong.

On top of this good naming habits help. After all functions do things and therefore there should be a verb in its name whereas classes represent objects and are nouns and adjectives with no verb.

var o = chair() // Executing chair is daft.
var o = createChair() // makes sense.

Its interesting how SO's syntax colouring has interpretted the code above.

Hibernate: best practice to pull all lazy collections

Use Hibernate.initialize() within @Transactional to initialize lazy objects.

 start Transaction 
 end Transaction 

Now out side of the Transaction you are able to get lazy objects.


Pandas - How to flatten a hierarchical index in columns

After reading through all the answers, I came up with this:

def __my_flatten_cols(self, how="_".join, reset_index=True):
    how = (lambda iter: list(iter)[-1]) if how == "last" else how
    self.columns = [how(filter(None, map(str, levels))) for levels in self.columns.values] \
                    if isinstance(self.columns, pd.MultiIndex) else self.columns
    return self.reset_index() if reset_index else self
pd.DataFrame.my_flatten_cols = __my_flatten_cols


Given a data frame:

df = pd.DataFrame({"grouper": ["x","x","y","y"], "val1": [0,2,4,6], 2: [1,3,5,7]}, columns=["grouper", "val1", 2])

  grouper  val1  2
0       x     0  1
1       x     2  3
2       y     4  5
3       y     6  7
  • Single aggregation method: resulting variables named the same as source:

    • Same as df.groupby(by="grouper", as_index=False) or .agg(...).reset_index()
    • ----- before -----
                 val1  2
      ------ after -----
        grouper  val1  2
      0       x     0  1
      1       y     4  5
  • Single source variable, multiple aggregations: resulting variables named after statistics:

    df.groupby(by="grouper").agg({"val1": [min,max]}).my_flatten_cols("last")
    • Same as a = df.groupby(..).agg(..); a.columns = a.columns.droplevel(0); a.reset_index().
    • ----- before -----
                 min max
      ------ after -----
        grouper  min  max
      0       x    0    2
      1       y    4    6
  • Multiple variables, multiple aggregations: resulting variables named (varname)_(statname):

    df.groupby(by="grouper").agg({"val1": min, 2:[sum, "size"]}).my_flatten_cols()
    # you can combine the names in other ways too, e.g. use a different delimiter:
    #df.groupby(by="grouper").agg({"val1": min, 2:[sum, "size"]}).my_flatten_cols(" ".join)
    • Runs a.columns = ["_".join(filter(None, map(str, levels))) for levels in a.columns.values] under the hood (since this form of agg() results in MultiIndex on columns).
    • If you don't have the my_flatten_cols helper, it might be easier to type in the solution suggested by @Seigi: a.columns = ["_".join(t).rstrip("_") for t in a.columns.values], which works similarly in this case (but fails if you have numeric labels on columns)
    • To handle the numeric labels on columns, you could use the solution suggested by @jxstanford and @Nolan Conaway (a.columns = ["_".join(tuple(map(str, t))).rstrip("_") for t in a.columns.values]), but I don't understand why the tuple() call is needed, and I believe rstrip() is only required if some columns have a descriptor like ("colname", "") (which can happen if you reset_index() before trying to fix up .columns)
    • ----- before -----
                 val1           2     
                 min       sum    size
      ------ after -----
        grouper  val1_min  2_sum  2_size
      0       x         0      4       2
      1       y         4     12       2
  • You want to name the resulting variables manually: (this is deprecated since pandas 0.20.0 with no adequate alternative as of 0.23)

    df.groupby(by="grouper").agg({"val1": {"sum_of_val1": "sum", "count_of_val1": "count"},
                                       2: {"sum_of_2":    "sum", "count_of_2":    "count"}}).my_flatten_cols("last")
    • Other suggestions include: setting the columns manually: res.columns = ['A_sum', 'B_sum', 'count'] or .join()ing multiple groupby statements.
    • ----- before -----
                         val1                      2         
                count_of_val1 sum_of_val1 count_of_2 sum_of_2
      ------ after -----
        grouper  count_of_val1  sum_of_val1  count_of_2  sum_of_2
      0       x              2            2           2         4
      1       y              2           10           2        12

Cases handled by the helper function

  • level names can be non-string, e.g. Index pandas DataFrame by column numbers, when column names are integers, so we have to convert with map(str, ..)
  • they can also be empty, so we have to filter(None, ..)
  • for single-level columns (i.e. anything except MultiIndex), columns.values returns the names (str, not tuples)
  • depending on how you used .agg() you may need to keep the bottom-most label for a column or concatenate multiple labels
  • (since I'm new to pandas?) more often than not, I want reset_index() to be able to work with the group-by columns in the regular way, so it does that by default

jQuery load first 3 elements, click "load more" to display next 5 elements

WARNING: size() was deprecated in jQuery 1.8 and removed in jQuery 3.0, use .length instead

Working Demo:

$(document).ready(function () {
    size_li = $("#myList li").size();
    $('#myList li:lt('+x+')').show();
    $('#loadMore').click(function () {
        x= (x+5 <= size_li) ? x+5 : size_li;
        $('#myList li:lt('+x+')').show();
    $('#showLess').click(function () {
        x=(x-5<0) ? 3 : x-5;
        $('#myList li').not(':lt('+x+')').hide();

New JS to show or hide load more and show less

$(document).ready(function () {
    size_li = $("#myList li").size();
    $('#myList li:lt('+x+')').show();
    $('#loadMore').click(function () {
        x= (x+5 <= size_li) ? x+5 : size_li;
        $('#myList li:lt('+x+')').show();
        if(x == size_li){
    $('#showLess').click(function () {
        x=(x-5<0) ? 3 : x-5;
        $('#myList li').not(':lt('+x+')').hide();
        if(x == 3){


#showLess {

Working Demo:

Python "extend" for a dictionary

You can also use python's collections.Chainmap which was introduced in python 3.3.

from collections import Chainmap
c = Chainmap(a, b)
c['a'] # returns 1

This has a few possible advantages, depending on your use-case. They are explained in more detail here, but I'll give a brief overview:

  • A chainmap only uses views of the dictionaries, so no data is actually copied. This results in faster chaining (but slower lookup)
  • No keys are actually overwritten so, if necessary, you know whether the data comes from a or b.

This mainly makes it useful for things like configuration dictionaries.

How can I decrypt MySQL passwords

With luck, if the original developer was any good, you will not be able to get the plain text out. I say "luck" otherwise you probably have an insecure system.

For the admin passwords, as you have the code, you should be able to create hashed passwords from a known plain text such that you can take control of the application. Follow the algorithm used by the original developer.

If they were not salted and hashed, then make sure you do apply this as 'best practice'

float:left; vs display:inline; vs display:inline-block; vs display:table-cell;

For the record only, to add to Spudley's answer, there is also the possibility to use position: absolute and margins if you know the column widths.

For me, the main issue when chossing a method is whether you need the columns to fill the whole height (equal heights), where table-cell is the easiest method (if you don't care much for older browsers).

CSS: Fix row height

HTML Table row heights will typically change proportionally to the table height, if the table height is larger than the height of your rows. Since the table is forcing the height of your rows, you can remove the table height to resolve the issue. If this is not acceptable, you can also give the rows explicit height, and add a third row that will auto size to the remaining table height.

Another option in CSS2 is the Max-Height Property, although it may lead to strange behavior in a table.


Reading rather large json files in Python

The issue here is that JSON, as a format, is generally parsed in full and then handled in-memory, which for such a large amount of data is clearly problematic.

The solution to this is to work with the data as a stream - reading part of the file, working with it, and then repeating.

The best option appears to be using something like ijson - a module that will work with JSON as a stream, rather than as a block file.

Edit: Also worth a look - kashif's comment about json-streamer and Henrik Heino's comment about bigjson.

Python Checking a string's first and last character

You should either use

if str1[0] == '"' and str1[-1] == '"'


if str1.startswith('"') and str1.endswith('"')

but not slice and check startswith/endswith together, otherwise you'll slice off what you're looking for...

int *array = new int[n]; what is this function actually doing?

int *array = new int[n];

It declares a pointer to a dynamic array of type int and size n.

A little more detailed answer: new allocates memory of size equal to sizeof(int) * n bytes and return the memory which is stored by the variable array. Also, since the memory is dynamically allocated using new, you've to deallocate it manually by writing (when you don't need anymore, of course):

delete []array;

Otherwise, your program will leak memory of at least sizeof(int) * n bytes (possibly more, depending on the allocation strategy used by the implementation).

Eclipse: The resource is not on the build path of a Java project

You can add the src folder to build path by:

  1. Select Java perspective.
  2. Right click on src folder.
  3. Select Build Path > Use a source folder.

And you are done. Hope this help.

EDIT: Refer to the Eclipse documentation

Git error: src refspec master does not match any

You've created a new repository and added some files to the index, but you haven't created your first commit yet. After you've done:

 git add a_text_file.txt 

... do:

 git commit -m "Initial commit."

... and those errors should go away.

Setting HTTP headers

I create wrapper for this case:

func addDefaultHeaders(fn http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Access-Control-Allow-Origin", "*")
        fn(w, r)

What is the use of the init() usage in JavaScript?

In JavaScript when you create any object through a constructor call like below

step 1 : create a function say Person..

function Person(name){;

step 2 : create an instance for this function..

var obj=new Person('venkat')

//above line will instantiate this function(Person) and return a brand new object called Person {name:'venkat'}

if you don't want to instantiate this function and call at same time.we can also do like below..

var Person = {
  init: function(name){;
  print: function(){
var obj=Object.create(Person);

in the above method init will help in instantiating the object properties. basically init is like a constructor call on your class.

How to get equal width of input and select fields

create another class and increase the with size with 2px example

width:278px !important; 

width:280px !important; 

Open Url in default web browser

Try this:

import React, { useCallback } from "react";
import { Linking } from "react-native";
OpenWEB = () => {

const App = () => {
  return <View onPress={() => OpenWeb}>OPEN YOUR WEB</View>;

Hope this will solve your problem.

Why does checking a variable against multiple values with `OR` only check the first value?

If you want case-insensitive comparison, use lower or upper:

if name.lower() == "jesse":

Closing JFrame with button click

It appears to me that you have two issues here. One is that JFrame does not have a close method, which has been addressed in the other answers.

The other is that you're having trouble referencing your JFrame. Within actionPerformed, super refers to ActionListener. To refer to the JFrame instance there, use MyExtendedJFrame.super instead (you should also be able to use MyExtendedJFrame.this, as I see no reason why you'd want to override the behaviour of dispose or setVisible).