Programs & Examples On #Delete row

Delete row refers to the removal of rows from a relational database.

Deleting records before a certain date

This is another example using defined column/table names.

DELETE FROM jos_jomres_gdpr_optins WHERE `date_time` < '2020-10-21 08:21:22';

DataTable, How to conditionally delete rows

You could query the dataset and then loop the selected rows to set them as delete.

var rows = dt.Select("col1 > 5");
foreach (var row in rows)

... and you could also create some extension methods to make it easier ...

myTable.Delete("col1 > 5");

public static DataTable Delete(this DataTable table, string filter)
    return table;
public static void Delete(this IEnumerable<DataRow> rows)
    foreach (var row in rows)

Deleting rows with MySQL LEFT JOIN

You simply need to specify on which tables to apply the DELETE.

Delete only the deadline rows:

DELETE `deadline` FROM `deadline` LEFT JOIN `job` ....

Delete the deadline and job rows:

DELETE `deadline`, `job` FROM `deadline` LEFT JOIN `job` ....

Delete only the job rows:

DELETE `job` FROM `deadline` LEFT JOIN `job` ....

Reset AutoIncrement in SQL Server after Delete

What about this?

ALTER TABLE `table_name`

This is a quick and simple way to change the auto increment to 0 or whatever number you want. I figured this out by exporting a database and reading the code myself.

You can also write it like this to make it a single-line solution:


Deleting Row in SQLite in Android

You can do something like this, sharing my working code snippet

Make sure query is like this

DELETE FROM tableName WHERE KEY__NAME = 'parameterToMatch'

public void removeSingleFeedback(InputFeedback itemToDelete) {
            //Open the database
            SQLiteDatabase database = this.getWritableDatabase();

            //Execute sql query to remove from database
            //NOTE: When removing by String in SQL, value must be enclosed with ''
            database.execSQL("DELETE FROM " + TABLE_FEEDBACKS + " WHERE "
                    + KEY_CUSTMER_NAME + "= '" + itemToDelete.getStrCustName() + "'" +
                    " AND " + KEY_DESIGNATION + "= '" + itemToDelete.getStrCustDesignation() + "'" +
                    " AND " + KEY_EMAIL + "= '" + itemToDelete.getStrCustEmail() + "'" +
                    " AND " + KEY_CONTACT_NO + "= '" + itemToDelete.getStrCustContactNo() + "'" +
                    " AND " + KEY_MOBILE_NO + "= '" + itemToDelete.getStrCustMobile() + "'" +
                    " AND " + KEY_CLUSTER_NAME + "= '" + itemToDelete.getStrClusterName() + "'" +
                    " AND " + KEY_PRODUCT_NAME + "= '" + itemToDelete.getStrProductName() + "'" +
                    " AND " + KEY_INSTALL_VERSION + "= '" + itemToDelete.getStrInstalledVersion() + "'" +
                    " AND " + KEY_REQUIREMENTS + "= '" + itemToDelete.getStrRequirements() + "'" +
                    " AND " + KEY_CHALLENGES + "= '" + itemToDelete.getStrChallenges() + "'" +
                    " AND " + KEY_EXPANSION + "= '" + itemToDelete.getStrFutureExpansion() + "'" +
                    " AND " + KEY_COMMENTS + "= '" + itemToDelete.getStrComments() + "'"

            //Close the database

Deleting specific rows from DataTable

You try this for getting and removing id column from data table

if (dt1.Columns.Contains("ID"))
    for (int i = dt1.Rows.Count - 1; i >= 0; i--)
        DataRow dr = dt1.Rows[i];

        if (dr["ID"].ToString() != "" && dr["ID"].ToString() != null)


Delete all data in SQL Server database

/* Drop all non-system stored procs */

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 ORDER BY [name])

WHILE @name is not null
    SELECT @SQL = 'DROP PROCEDURE [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Procedure: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'P' AND category = 0 AND [name] > @name ORDER BY [name])

/* Drop all views */

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 ORDER BY [name])

    SELECT @SQL = 'DROP VIEW [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped View: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'V' AND category = 0 AND [name] > @name ORDER BY [name])

/* Drop all functions */

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 ORDER BY [name])

    SELECT @SQL = 'DROP FUNCTION [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Function: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] IN (N'FN', N'IF', N'TF', N'FS', N'FT') AND category = 0 AND [name] > @name ORDER BY [name])

/* Drop all Foreign Key constraints */
DECLARE @constraint VARCHAR(254)


WHILE @name is not null
    WHILE @constraint IS NOT NULL
        SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint) +']'
        EXEC (@SQL)
        PRINT 'Dropped FK Constraint: ' + @constraint + ' on ' + @name

/* Drop all Primary Key constraints */
DECLARE @constraint VARCHAR(254)


    WHILE @constraint is not null
        SELECT @SQL = 'ALTER TABLE [dbo].[' + RTRIM(@name) +'] DROP CONSTRAINT [' + RTRIM(@constraint)+']'
        EXEC (@SQL)
        PRINT 'Dropped PK Constraint: ' + @constraint + ' on ' + @name

/* Drop all tables */

SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 ORDER BY [name])

    SELECT @SQL = 'DROP TABLE [dbo].[' + RTRIM(@name) +']'
    EXEC (@SQL)
    PRINT 'Dropped Table: ' + @name
    SELECT @name = (SELECT TOP 1 [name] FROM sysobjects WHERE [type] = 'U' AND category = 0 AND [name] > @name ORDER BY [name])

How to delete a certain row from mysql table with same column values?

You must add an id that auto-increment for each row, after that you can delet the row by its id. so your table will have an unique id for each row and the id_user, id_product ecc...

Difference between Destroy and Delete

Basically "delete" sends a query directly to the database to delete the record. In that case Rails doesn't know what attributes are in the record it is deleting nor if there are any callbacks (such as before_destroy).

The "destroy" method takes the passed id, fetches the model from the database using the "find" method, then calls destroy on that. This means the callbacks are triggered.

You would want to use "delete" if you don't want the callbacks to be triggered or you want better performance. Otherwise (and most of the time) you will want to use "destroy".

MySQL InnoDB not releasing disk space after deleting data rows from table

There are several ways to reclaim diskspace after deleting data from table for MySQL Inodb engine

If you don't use innodb_file_per_table from the beginning, dumping all data, delete all file, recreate database and import data again is only way ( check answers of FlipMcF above )

If you are using innodb_file_per_table, you may try

  1. If you can delete all data truncate command will delete data and reclaim diskspace for you.
  2. Alter table command will drop and recreate table so it can reclaim diskspace. Therefore after delete data, run alter table that change nothing to release hardisk ( ie: table TBL_A has charset uf8, after delete data run ALTER TABLE TBL_A charset utf8 -> this command change nothing from your table but It makes mysql recreate your table and regain diskspace
  3. Create TBL_B like TBL_A . Insert select data you want to keep from TBL_A into TBL_B. Drop TBL_A, and rename TBL_B to TBL_A. This way is very effective if TBL_A and data that needed to delete is big (delete command in MySQL innodb is very bad performance)

deleting rows in numpy array

import numpy as np 
arr = np.array([[ 0.96488889, 0.73641667, 0.67521429, 0.592875, 0.53172222],[ 0.78008333, 0.5938125, 0.481, 0.39883333, 0.]])
print(arr[np.where(arr != 0.)])

Delete a row from a SQL Server table

private void button4_Click(object sender, EventArgs e)
    String st = "DELETE FROM supplier WHERE supplier_id =" + textBox1.Text;

    SqlCommand sqlcom = new SqlCommand(st, myConnection);
        MessageBox.Show("delete successful");
    catch (SqlException ex)

private void button6_Click(object sender, EventArgs e)
    String st = "SELECT * FROM suppliers";

    SqlCommand sqlcom = new SqlCommand(st, myConnection);
        SqlDataReader reader = sqlcom.ExecuteReader();
        DataTable datatable = new DataTable();
        dataGridView1.DataSource = datatable;
    catch (SqlException ex)

How to delete a row from GridView?

You're deleting the row from the gridview and then rebinding it to the datasource (which still contains the row). Either delete the row from the datasource, or don't rebind the gridview afterwards.

Removing duplicate rows from table in Oracle

DELETE FROM tablename a
                             FROM tablename b
                            WHERE a.fieldname = b.fieldname
                              AND a.fieldname2 = b.fieldname2)

SQL DELETE with JOIN another table for WHERE condition

I think, from your description, the following would suffice:

DELETE FROM guide_category 
WHERE id_guide NOT IN (SELECT id_guide FROM guide)

I assume, that there are no referential integrity constraints on the tables involved, are there?

Should URL be case sensitive?

The case sensitivity of URLs, in general (along with whether they are same or not if they are in different case), needs to be looked at from the following perspectives:

  • Resource Equivalence
  • URL Comparison

From the perspective of resource equivalence it is generally not possible to say two URLs differing by any case (lower case, upper case, sentence case, camel case ... any combination of case) are different from each other unless the resource is retrieved from both the URLs, which in many cases is not practical (RFC 3986, section 6.1, para 1). Therefore where the resource cannot be retrieved, the comparison perspective is used.

However, in case where it is possible to retrieve the resource, the matter gets more (as expected) complicated. By the provisions of RFC 3986, Section 3.3, para 5, as highlighted below

Aside from dot-segments in hierarchical paths, a path segment is considered opaque by the generic syntax

it would appear that no assumption can be made for the rest of a URI/URL beyond it's scheme and authority from generic syntax (inclusive of the sensitivity question).

For scheme and host part of the authority, however, the specification does (charitably) state them to be case insensitive. Refer RFC 3986, section 3.1, para 1 and RFC 3986, section, para 2.

Having exhausted this line of inquiry one should look at the comparison perspective to determine whether URI/URLs are to be case sensitive or not.

The first hint to that direction emerges through perusal of the section (above)

The other generic syntax components are assumed to be case-sensitive unless specifically defined otherwise by the scheme

Which is further buoyed by considering RFC 2616, section 3.2.3

When comparing two URIs to decide if they match or not, a client SHOULD use a case-sensitive octet-by-octet comparison of the entire URIs

Then, finally, is the enquiry settled and URLs are case sensitive ... (heh!), not quite, the operative words are 'opaque', 'client' and 'comparing'.

Beyond it's syntax, The above RFC don't mention anything about the actual interpretation of the path and query except that it is 'opaque' and it only specifies how (with a SHOULD and not a MUST) a 'client' may 'compare' the URL. It mentions nothing regarding how a server (SHOULD, let alone MUST) interpret the rest of the URL beyond scheme/authority.

Therefore the server has all the latitude to interpret an URL as they please, which they do as highlighted by earlier posts by others.

Does Java have a complete enum for HTTP response codes?

Another option is to use HttpStatus class from the Apache commons-httpclient which provides you the various Http statuses as constants.

Rounding BigDecimal to *always* have two decimal places

value = value.setScale(2, RoundingMode.CEILING)

Convert List to Pandas Dataframe Column

You can directly call the


method and pass your list as parameter.

l = ['Thanks You','Its fine no problem','Are you sure']


0            Thanks You
1   Its fine no problem
2          Are you sure

And if you have multiple lists and you want to make a dataframe out of it.You can do it as following:

import pandas as pd
names =["A","B","C","D"]
salary =[50000,90000,41000,62000]
age = [24,24,23,25]
data = pd.DataFrame([names,salary,age]) #Each list would be added as a row
data = data.transpose() #To Transpose and make each rows as columns
data.columns=['Names','Salary','Age'] #Rename the columns


    Names   Salary  Age
0       A    50000   24
1       B    90000   24
2       C    41000   23
3       D    62000   25

Count cells that contain any text

You can pass "<>" (including the quotes) as the parameter for criteria. This basically says, as long as its not empty/blank, count it. I believe this is what you want.

=COUNTIF(A1:A10, "<>") 

Otherwise you can use CountA as Scott suggests

What is android:ems attribute in Edit Text?

Taken from:

The em is simply the font size. In an element with a 2in font, 1em thus means 2in. Expressing sizes, such as margins and paddings, in em means they are related to the font size, and if the user has a big font (e.g., on a big screen) or a small font (e.g., on a handheld device), the sizes will be in proportion. Declarations such as 'text-indent: 1.5em' and 'margin: 1em' are extremely common in CSS.

em is basically CSS property for font sizes.

Firefox 'Cross-Origin Request Blocked' despite headers

I found that my problem was that the server I've sent the cross request to had a certificate that was not trusted.

If you want to connect to a cross domain with https, you have to add an exception for this certificate first.

You can do this by visiting the blocked link once and addibng the exception.

How to set python variables to true or false?

Python boolean keywords are True and False, notice the capital letters. So like this:

a = True;
b = True;
match_var = True if a == b else False
print match_var;

When compiled and run, this prints:


SASS :not selector

I tried re-creating this, and .someclass.notip was being generated for me but .someclass:not(.notip) was not, for as long as I did not have the @mixin tip() defined. Once I had that, it all worked.

$dropdown-width: 100px;
$comp-tip: true;

@mixin tip($pos:right) {


@mixin dropdown-pos($pos:right) {
  &:not(.notip) {
    @if $comp-tip == true{
      @if $pos == right {
        top:$dropdown-width * -0.6;
        background-color: #f00;
        @include tip($pos:$pos);
  &.notip {
    @if $pos == right {
      top: 0;
      left:$dropdown-width * 0.8;
      background-color: #00f;

.someclass { @include dropdown-pos(); }

EDIT: is a good place to debug your SASS because it gives you error messages. Undefined mixin 'tip'. it what I get when I remove @mixin tip($pos:right) { }

Multiplying Two Columns in SQL Server


SELECT <Expression>[Arithmetic_Operator]<expression>...
 FROM [Table_Name] 
 WHERE [expression];
  1. Expression : Expression made up of a single constant, variable, scalar function, or column name and can also be the pieces of a SQL query that compare values against other values or perform arithmetic calculations.
  2. Arithmetic_Operator : Plus(+), minus(-), multiply(*), and divide(/).
  3. Table_Name : Name of the table.

Java simple code: Unexpected end of file from server


This exception is encountered when you are expecting a response, but the socket has been abruptly closed.

Detailed Explanation

Java's HTTPClient, found here, throws a SocketException with message "Unexpected end of file from server" in a very specific circumstance.

After making a request, HTTPClient gets an InputStream tied to the socket associated with the request. It then polls that InputStream repeatedly until it either:

  1. Finds the string "HTTP/1."
  2. The end of the InputStream is reached before 8 characters are read
  3. Finds a string other than "HTTP/1."

In case of number 2, HTTPClient will throw this SocketException if any of the following are true:

  • The HTTP method is CONNECT
  • The HTTP method is POST and the client is set to streaming mode

Why would this happen

This indicates that the TCP socket has been closed before the server was able to send a response. This could happen for any number of reasons, but some possibilities are:

  • Network connection was lost
  • The server decided to close the connection
  • Something in between the client and the server (nginx, router, etc) terminated the request

Note: When Nginx reloads its config, it forcefully closes any in-flight HTTP Keep-Alive connections (even POSTs), causing this exact error.

How do I fix a "Performance counter registry hive consistency" when installing SQL Server R2 Express?

Use Rafael's solution:

Added data from link to avoid link rot..

put this at any Console application:

string.Format("{0,3}", CultureInfo.InstalledUICulture.Parent.LCID.ToString("X")).Replace(" ", "0");

Watch the result. At mine it was "016".

Then you go to the registry at this key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib

and create another one with the name you got from the string.Format result.

In my case:

"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib\016"

and copy the info that is on any other key in this Perflib to this key you just created. Run the instalation again.

Just run the script and get your 3 digit code. Then follow his simple and quick steps, and you're ready to go!


Xcode Product -> Archive disabled

You've changed your scheme destination to a simulator instead of Generic iOS Device.

That's why it is greyed out.

Change from a simulator to Generic iOS Device

How to style the UL list to a single line

ul li{
  display: inline;

For more see the basic list options and a basic horizontal list at listamatic. (thanks to Daniel Straight below for the links).

Also, as pointed out in the comments, you probably want styling on the ul and whatever elements go inside the li's and the li's themselves to get things to look nice.

What is a software framework?

Technically, you don't need a framework. If you're making a really really simple site (think of the web back in 1992), you can just do it all with hard-coded HTML and some CSS.

And if you want to make a modern webapp, you don't actually need to use a framework for that, either.

You can instead choose to write all of the logic you need yourself, every time. You can write your own data-persistence/storage layer, or - if you're too busy - just write custom SQL for every single database access. You can write your own authentication and session handling layers. And your own template rending logic. And your own exception-handling logic. And your own security functions. And your own unit test framework to make sure it all works fine. And your own... [goes on for quite a long time]

Then again, if you do use a framework, you'll be able to benefit from the good, usually peer-reviewed and very well tested work of dozens if not hundreds of other developers, who may well be better than you. You'll get to build what you want rapidly, without having to spend time building or worrying too much about the infrastructure items listed above.

You can get more done in less time, and know that the framework code you're using or extending is very likely to be done better than you doing it all yourself.

And the cost of this? Investing some time learning the framework. But - as virtually every web dev out there will attest - it's definitely worth the time spent learning to get massive (really, massive) benefits from using whatever framework you choose.

Python: One Try Multiple Except

Yes, it is possible.

except FirstException:

except SecondException:

except (ThirdException, FourthException, FifthException) as e:

except Exception:


The "as" keyword is used to assign the error to a variable so that the error can be investigated more thoroughly later on in the code. Also note that the parentheses for the triple exception case are needed in python 3. This page has more info: Catch multiple exceptions in one line (except block)

Limiting the number of characters in a string, and chopping off the rest

Use this to cut off the non needed characters:

String.substring(0, maxLength); 


String aString ="123456789";
String cutString = aString.substring(0, 4);
// Output is: "1234" 

To ensure you are not getting an IndexOutOfBoundsException when the input string is less than the expected length do the following instead:

int maxLength = (inputString.length() < MAX_CHAR)?inputString.length():MAX_CHAR;
inputString = inputString.substring(0, maxLength);

If you want your integers and doubles to have a certain length then I suggest you use NumberFormat to format your numbers instead of cutting off their string representation.

Maven - Failed to execute goal org.apache.maven.plugins:maven-clean-plugin:2.4.1:clean

Failed to delete C:\EclipseProjects\myGoogleAppEngine\target\myGoogleAppEngine-0.0.1-SNAPSHOT\WEB-INF\lib\spring-webmvc-3.1.0.RELEASE.jar

Because of the path C:\EclipseProjects i guess you have eclipse running on that project. If you application runs, you cannot clean the output, because it may be in use.

Stop the application and maybe eclipse and try again.

Add Twitter Bootstrap icon to Input box

Bootstrap 4.x with 3 different way.

  1. Icon with default bootstrap Style Icon with default bootstrap Style

    <div class="input-group">
          <input type="text" class="form-control" placeholder="From" aria-label="from" aria-describedby="from">
          <div class="input-group-append">
            <span class="input-group-text"><i class="fas fa-map-marker-alt"></i></span>
  2. Icon Inside Input with default bootstrap class Icon Inside Input with default bootstrap class

    <div class="input-group">
          <input type="text" class="form-control border-right-0" placeholder="From" aria-label="from" aria-describedby="from">
          <div class="input-group-append">
            <span class="input-group-text bg-transparent"><i class="fas fa-map-marker-alt"></i></span>
  3. Icon Inside Input with small custom css Icon Inside Input with small custom css

    <div class="input-group">
          <input type="text" class="form-control rounded-right" placeholder="From" aria-label="from" aria-describedby="from">
            <span class="icon-inside"><i class="fas fa-map-marker-alt"></i></span>

    Custom Css

    .icon-inside {
          position: absolute;
          right: 10px;
          top: calc(50% - 12px);
          pointer-events: none;
          font-size: 16px;
          font-size: 1.125rem;
          color: #c4c3c3;

.icon-inside {_x000D_
      position: absolute;_x000D_
      right: 10px;_x000D_
      top: calc(50% - 12px);_x000D_
      pointer-events: none;_x000D_
      font-size: 16px;_x000D_
      font-size: 1.125rem;_x000D_
      color: #c4c3c3;_x000D_
<link rel="stylesheet" type="text/css" href="" />_x000D_
    <link rel="stylesheet" href="" integrity="sha384-hWVjflwFxL6sNzntih27bfxkr27PmbbK/iSvJ+a4+0owXq79v+lsFkW54bOGbiDQ" crossorigin="anonymous">_x000D_
    <div class="container">_x000D_
    <h5 class="mt-3">Icon <small>with default bootstrap Style</small><h5>_x000D_
    <div class="input-group">_x000D_
      <input type="text" class="form-control" placeholder="From" aria-label="from" aria-describedby="from">_x000D_
      <div class="input-group-append">_x000D_
        <span class="input-group-text"><i class="fas fa-map-marker-alt"></i></span>_x000D_
    <h5 class="mt-3">Icon Inside Input <small>with default bootstrap class</small><h5>_x000D_
    <div class="input-group">_x000D_
      <input type="text" class="form-control border-right-0" placeholder="From" aria-label="from" aria-describedby="from">_x000D_
      <div class="input-group-append">_x000D_
        <span class="input-group-text bg-transparent"><i class="fas fa-map-marker-alt"></i></span>_x000D_
    <h5 class="mt-3">Icon Inside Input<small> with small custom css</small><h5>_x000D_
    <div class="input-group">_x000D_
      <input type="text" class="form-control rounded-right" placeholder="From" aria-label="from" aria-describedby="from">_x000D_
        <span class="icon-inside"><i class="fas fa-map-marker-alt"></i></span>_x000D_

How do I solve the "server DNS address could not be found" error on Windows 10?

Steps to manually configure DNS:

  1. You can access Network and Sharing center by right clicking on the Network icon on the taskbar.

  2. Now choose adapter settings from the side menu.

  3. This will give you a list of the available network adapters in the system . From them right click on the adapter you are using to connect to the internet now and choose properties option.

  4. In the networking tab choose ‘Internet Protocol Version 4 (TCP/IPv4)’.

  5. Now you can see the properties dialogue box showing the properties of IPV4. Here you need to change some properties.

    Select ‘use the following DNS address’ option. Now fill the following fields as given here.

    Preferred DNS server:

    Alternate DNS server :

    This is an available Open DNS address. You may also use google DNS server addresses.

    After filling these fields. Check the ‘validate settings upon exit’ option. Now click OK.

You have to add this DNS server address in the router configuration also (by referring the router manual for more information).

Refer : for above method & alternative

If none of this works, then open command prompt(Run as Administrator) and run these:

ipconfig /flushdns
ipconfig /registerdns
ipconfig /release
ipconfig /renew
NETSH winsock reset catalog
NETSH int ipv4 reset reset.log
NETSH int ipv6 reset reset.log

Hopefully that fixes it, if its still not fixed there is a chance that its a NIC related issue(driver update or h/w).

Also FYI, this has a thread on Microsoft community : Windows 10 - DNS Issue

java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet

You need to add the "Maven Dependency" in the Deployment Assembly

  • right click on your project and choose properties.
  • click on Deployment Assembly.
  • click add
  • click on "Java Build Path Entries"
  • select Maven Dependencies"
  • click Finish.

Rebuild and deploy again

Note: This is also applicable for non maven project.

Chrome Dev Tools - Modify javascript and reload

The Resource Override extension allows you to do exactly that:

  • create a file rule for the url you want to replace
  • edit the js/css/etc in the extension
  • reload as often as you want :)

How to disable the parent form when a child form is active?

You can do that with the following:

Form3 formshow = new Form3();


Reading a UTF8 CSV file with Python

The .encode method gets applied to a Unicode string to make a byte-string; but you're calling it on a byte-string instead... the wrong way 'round! Look at the codecs module in the standard library and in particular for better general solutions for reading UTF-8 encoded text files. However, for the csv module in particular, you need to pass in utf-8 data, and that's what you're already getting, so your code can be much simpler:

import csv

def unicode_csv_reader(utf8_data, dialect=csv.excel, **kwargs):
    csv_reader = csv.reader(utf8_data, dialect=dialect, **kwargs)
    for row in csv_reader:
        yield [unicode(cell, 'utf-8') for cell in row]

filename = 'da.csv'
reader = unicode_csv_reader(open(filename))
for field1, field2, field3 in reader:
  print field1, field2, field3 

PS: if it turns out that your input data is NOT in utf-8, but e.g. in ISO-8859-1, then you do need a "transcoding" (if you're keen on using utf-8 at the csv module level), of the form line.decode('whateverweirdcodec').encode('utf-8') -- but probably you can just use the name of your existing encoding in the yield line in my code above, instead of 'utf-8', as csv is actually going to be just fine with ISO-8859-* encoded bytestrings.

Visual Studio: LINK : fatal error LNK1181: cannot open input file

I had the same problem. Solved it by defining a macro OBJECTS that contains all the linker objects e.g.:

OBJECTS = target.exe kernel32.lib mylib.lib (etc)

And then specifying $(OBJECTS) on the linker's command line.

I don't use Visual Studio though, just nmake and a .MAK file

Comparison of DES, Triple DES, AES, blowfish encryption for data

                DES                               AES
Developed       1977                              2000
Key Length      56 bits                           128, 192, or 256 bits
Cipher Type     Symmetric                         Symmetric
Block Size      64 bits                           128 bits
Security        inadequate                        secure
Performance     Fast                              Slow

How can I conditionally import an ES6 module?

Look at this example for clear understanding of how dynamic import works.

Dynamic Module Imports Example

To have Basic Understanding of importing and exporting Modules.

JavaScript modules Github

Javascript Modules MDN

How to properly create an SVN tag from trunk?

You are correct in that it's not "right" to add files to the tags folder.

You've correctly guessed that copy is the operation to use; it lets Subversion keep track of the history of these files, and also (I assume) store them much more efficiently.

In my experience, it's best to do copies ("snapshots") of entire projects, i.e. all files from the root check-out location. That way the snapshot can stand on its own, as a true representation of the entire project's state at a particular point in time.

This part of "the book" shows how the command is typically used.

How to redirect to another page using AngularJS?

A good way to do this is using $state.go('statename', {params...}) is faster and more friendly for user experience in cases when you don't have to reload and bootsraping whole app config and stuff

(function() {
    'use strict';

        .controller('YourController', YourController);

    YourController.$inject = ['rootURL', '$scope', '$state', '$http'];

    function YourController(rootURL, $scope, $state, $http) {

                url: rootURL + 'app-code/common.service.php',
                method: "POST",
                headers: {'Content-Type': 'application/x-www-form-urlencoded'},
                dataType: 'json',
                data:data + '&method=signin'

            }).success(function (response) {
                if (response['code'] == '420') {

                    $scope.message = response['message'];
                    $scope.loginPassword = '';
                } else if (response['code'] != '200') {

                    $scope.message = response['message'];
                    $scope.loginPassword = '';
                } else {
                    // $state.go('home'); // select here the route that you want to redirect
                    $state.go(response['state']); // response['state'] should be a route on your app.routes


// routes

(function() {
    'use strict';


    routes.$inject = [

    function routes($stateProvider, $urlRouterProvider) {
         * Default path for any unmatched url

            .state('home', {
                url: '/',
                templateUrl: '/app/home/home.html',
                controller: 'Home'
            .state('login', {
                url: '/login',
                templateUrl: '/app/login/login.html',
                controller: 'YourController'
            // ... more routes .state


How to see the changes between two commits without commits in-between?

I wrote a script which displays diff between two commits, works well on Ubuntu.

#!/usr/bin/env python
import sys, subprocess, os

TOOLS = ['bcompare', 'meld']

def getTool():
    for tool in TOOLS:
            out = subprocess.check_output(['which', tool]).strip()
            if tool in out:
                return tool
        except subprocess.CalledProcessError:
    return None

def printUsageAndExit():
    print 'Usage: python <project> <commit_one> <commit_two>'
    print 'Example: python <project> 0 1'
    print 'Example: python <project> fhejk7fe d78ewg9we'
    print 'Example: python <project> 0 d78ewg9we'

def getCommitIds(name, first, second):
    commit1 = None
    commit2 = None
        first_index = int(first) - 1
        second_index = int(second) - 1
        if int(first) < 0 or int(second) < 0:
            print "Cannot handle negative values: "
        logs = subprocess.check_output(['git', '-C', name, 'log', '--oneline', '--reverse']).split('\n')
        if first_index >= 0:
            commit1 = logs[first_index].split(' ')[0]
        if second_index >= 0:
            commit2 = logs[second_index].split(' ')[0]
    except ValueError:
        if first != '0':
            commit1 = first
        if second != '0':
            commit2 = second
    return commit1, commit2

def validateCommitIds(name, commit1, commit2):
    if commit1 == None and commit2 == None:
        print "Nothing to do, exit!"
        return False
        if commit1 != None:
            subprocess.check_output(['git', '-C', name, 'cat-file', '-t', commit1]).strip()
        if commit2 != None:
            subprocess.check_output(['git', '-C', name, 'cat-file', '-t', commit2]).strip()
    except subprocess.CalledProcessError:
        return False
    return True

def cleanup(commit1, commit2):
        subprocess.check_output(['rm', '-rf', '/tmp/'+(commit1 if commit1 != None else '0'), '/tmp/'+(commit2 if commit2 != None else '0')])

def checkoutCommit(name, commit):
    if commit != None:
        subprocess.check_output(['git', 'clone', name, '/tmp/'+commit])
        subprocess.check_output(['git', '-C', '/tmp/'+commit, 'checkout', commit])
        subprocess.check_output(['mkdir', '/tmp/0'])

def compare(tool, commit1, commit2):
        subprocess.check_output([tool, '/tmp/'+(commit1 if commit1 != None else '0'), '/tmp/'+(commit2 if commit2 != None else '0')])

if __name__=='__main__':
    tool = getTool()
    if tool == None:
        print "No GUI diff tools"
    if len(sys.argv) != 4:

    name, first, second = None, 0, 0
        name, first, second = sys.argv[1], sys.argv[2], sys.argv[3]
    except IndexError:

    commit1, commit2 = getCommitIds(name, first, second)

    if not validateCommitIds(name, commit1, commit2):

    cleanup(commit1, commit2)
    checkoutCommit(name, commit1)
    checkoutCommit(name, commit2)

        compare(tool, commit1, commit2)
    except KeyboardInterrupt:
        cleanup(commit1, commit2)

Using Eloquent ORM in Laravel to perform search of database using LIKE

Use double quotes instead of single quote eg :

where('', 'LIKE', "%$findcustomer%")

Below is my code:

public function searchCustomer($findcustomer)
    $customer = DB::table('customer')
                  ->where('', 'LIKE', "%$findcustomer%")
                  ->orWhere('', 'LIKE', "%$findcustomer%")

    return View::make("your view here");

Change visibility of ASP.NET label with JavaScript

You need to be wary of XSS when doing stuff like this:

document.getElementById('<%= Label1.ClientID %>').style.display

The chances are that no-one will be able to tamper with the ClientID of Label1 in this instance, but just to be on the safe side you might want pass it's value through one of the AntiXss library's methods:

document.getElementById('<%= AntiXss.JavaScriptEncode(Label1.ClientID) %>').style.display

Rotate an image in image source in html

You can do this:

<img src="your image" style="transform:rotate(90deg);">

it is much easier.

outline on only one border

You can use box-shadow to create an outline on one side. Like outline, box-shadow does not change the size of the box model.

This puts a line on top:

box-shadow: 0 -1px 0 #000;

I made a jsFiddle where you can check it out in action.


For an inset border, use the inset keyword. This puts an inset line on top:

box-shadow: 0 1px 0 #000 inset;

Multiple lines can be added using comma-separated statements. This puts an inset line on the top and the left:

box-shadow: 0 1px 0 #000 inset,
            1px 0 0 #000 inset;

For more details on how box-shadow works, check out the MDN page.

How to import JSON File into a TypeScript file?

I couldn't import a different file.json too. But I resolved it like this

const swaggerDoc = require('../swagger.json')

Using (Ana)conda within PyCharm

Change the project interpreter to ~/anaconda2/python/bin by going to File -> Settings -> Project -> Project Interpreter. Also update the run configuration to use the project default Python interpreter via Run -> Edit Configurations. This makes PyCharm use Anaconda instead of the default Python interpreter under usr/bin/python27.

versionCode vs versionName in Android Manifest

Version Code Represent Version of Your code, android OS check for update by using this variable whether this code is old or new.

Version Name Represent name of version in the format-


String, used for readable string only, functionally version code has been used by OS.

How to convert char to integer in C?

The standard function atoi() will likely do what you want.

A simple example using "atoi":

#include <unistd.h>

int main(int argc, char *argv[])
    int useconds = atoi(argv[1]); 

How to increase an array's length

If you don't want or cannot use ArrayList, then there is a utility method:


that will allow you to specify new size, while preserving the elements.

"Specified argument was out of the range of valid values"

I was also getting same issue as i tried using value 0 in non-based indexing,i.e starting with 1, not with zero

HTML5 tag for horizontal line break

Simply use hr tag in HTML file and add below code in CSS file .

    hr {
       display: block;
       position: relative;
       padding: 0;
       margin: 8px auto;
       height: 0;
       width: 100%;
       max-height: 0;
       font-size: 1px;
       line-height: 0;
       clear: both;
       border: none;
       border-top: 1px solid #aaaaaa;
       border-bottom: 1px solid #ffffff;

it works perfectly .

C# list.Orderby descending


var newList = list.OrderByDescending(x => x.Product.Name).ToList();

Doc: OrderByDescending(IEnumerable, Func).

In response to your comment:

var newList = list.OrderByDescending(x => x.Product.Name)
                  .ThenBy(x => x.Product.Price)

Set value for particular cell in pandas DataFrame with iloc

To modify the value in a cell at the intersection of row "r" (in column "A") and column "C"

  1. retrieve the index of the row "r" in column "A"

        i = df[ df['A']=='r' ].index.values[0]
  2. modify the value in the desired column "C"


Note: before, be sure to reset the index of rows have a nice index list!


Completely cancel a rebase

In the case of a past rebase that you did not properly aborted, you now (Git 2.12, Q1 2017) have git rebase --quit

See commit 9512177 (12 Nov 2016) by Nguy?n Thái Ng?c Duy (pclouds). (Merged by Junio C Hamano -- gitster -- in commit 06cd5a1, 19 Dec 2016)

rebase: add --quit to cleanup rebase, leave everything else untouched

There are occasions when you decide to abort an in-progress rebase and move on to do something else but you forget to do "git rebase --abort" first. Or the rebase has been in progress for so long you forgot about it. By the time you realize that (e.g. by starting another rebase) it's already too late to retrace your steps. The solution is normally

rm -r .git/<some rebase dir>

and continue with your life.
But there could be two different directories for <some rebase dir> (and it obviously requires some knowledge of how rebase works), and the ".git" part could be much longer if you are not at top-dir, or in a linked worktree. And "rm -r" is very dangerous to do in .git, a mistake in there could destroy object database or other important data.

Provide "git rebase --quit" for this use case, mimicking a precedent that is "git cherry-pick --quit".

Before Git 2.27 (Q2 2020), The stash entry created by "git merge --autostash" to keep the initial dirty state were discarded by mistake upon "git rebase --quit", which has been corrected.

See commit 9b2df3e (28 Apr 2020) by Denton Liu (Denton-L).
(Merged by Junio C Hamano -- gitster -- in commit 3afdeef, 29 Apr 2020)

rebase: save autostash entry into stash reflog on --quit

Signed-off-by: Denton Liu

In a03b55530a ("merge: teach --autostash option", 2020-04-07, Git v2.27.0 -- merge listed in batch #5), the --autostash option was introduced for git merge.

(See "Can “git pull” automatically stash and pop pending changes?")

Notably, when git merge --quit is run with an autostash entry present, it is saved into the stash reflog.

This is contrasted with the current behaviour of git rebase --quit where the autostash entry is simply just dropped out of existence.

Adopt the behaviour of git merge --quit in git rebase --quit and save the autostash entry into the stash reflog instead of just deleting it.

How to use Session attributes in Spring-mvc

In Spring 4 Web MVC. You can use @SessionAttribute in the method with @SessionAttributes in Controller level

public class OrderController extends BaseController {

    public String showPage(@SessionAttribute("SessionKey") SearchCriteria searchCriteria) {
     // method body

What is the difference among col-lg-*, col-md-* and col-sm-* in Bootstrap?

enter image description here

I think this image is pretty good to understand the concept better!

for more detail understanding please go though below link:

What's the purpose of the LEA instruction?

lea is an abbreviation of "load effective address". It loads the address of the location reference by the source operand to the destination operand. For instance, you could use it to:

lea ebx, [ebx+eax*8]

to move ebx pointer eax items further (in a 64-bit/element array) with a single instruction. Basically, you benefit from complex addressing modes supported by x86 architecture to manipulate pointers efficiently.

How can I check if PostgreSQL is installed or not via Linux script?

And if everything else fails from these great choice of answers, you can always use "find" like this. Or you may need to use sudo

If you are root, just type $$> find / -name 'postgres'

If you are a user, you will need sudo priv's to run it through all the directories

I run it this way, from the / base to find the whole path that the element is found in. This will return any files or directories with the "postgres" in it.

You could do the same thing looking for the pg_hba.conf or postgresql.conf files also.

sum two columns in R

You can do this :

    df <- data.frame("a" = c(1,2,3,4), "b" = c(4,3,2,1), "x_ind" = c(1,0,1,1), "y_ind" = c(0,0,1,1), "z_ind" = c(0,1,1,1) )
df %>% mutate( bi  = ifelse((df$x_ind + df$y_ind +df$z_ind)== 3, 1,0 ))

Which is faster: multiple single INSERTs or one multiple-row INSERT?

You might want to :

  • Check that auto-commit is off
  • Open Connection
  • Send multiple batches of inserts in a single transaction (size of about 4000-10000 rows ? you see)
  • Close connection

Depending on how well your server scales (its definitively ok with PostgreSQl, Oracle and MSSQL), do the thing above with multiple threads and multiple connections.

Java synchronized block vs. Collections.synchronizedMap

Yes, you are synchronizing correctly. I will explain this in more detail. You must synchronize two or more method calls on the synchronizedMap object only in a case you have to rely on results of previous method call(s) in the subsequent method call in the sequence of method calls on the synchronizedMap object. Let’s take a look at this code:

synchronized (synchronizedMap) {
    if (synchronizedMap.containsKey(key)) {
    else {
        List<String> valuesList = new ArrayList<String>();
        synchronizedMap.put(key, valuesList);

In this code



synchronizedMap.put(key, valuesList);

method calls are relied on the result of the previous


method call.

If the sequence of method calls were not synchronized the result might be wrong. For example thread 1 is executing the method addToMap() and thread 2 is executing the method doWork() The sequence of method calls on the synchronizedMap object might be as follows: Thread 1 has executed the method


and the result is "true". After that operating system has switched execution control to thread 2 and it has executed


After that execution control has been switched back to the thread 1 and it has executed for example


believing the synchronizedMap object contains the key and NullPointerException will be thrown because synchronizedMap.get(key) will return null. If the sequence of method calls on the synchronizedMap object is not dependent on the results of each other then you don't need to synchronize the sequence. For example you don't need to synchronize this sequence:

synchronizedMap.put(key1, valuesList1);
synchronizedMap.put(key2, valuesList2);


synchronizedMap.put(key2, valuesList2);

method call does not rely on the results of the previous

synchronizedMap.put(key1, valuesList1);

method call (it does not care if some thread has interfered in between the two method calls and for example has removed the key1).

How to break out of while loop in Python?

What I would do is run the loop until the ans is Q

while not ans=='Q':
    print('Your score is so far '+str(myScore)+'.')
    print("Would you like to roll or quit?")
    if ans=='R':
        R=random.randint(1, 8)
        print("You rolled a "+str(R)+".")

Mongoose: CastError: Cast to ObjectId failed for value "[object Object]" at path "_id"

I also encountered this mongoose error CastError: Cast to ObjectId failed for value \"583fe2c488cf652d4c6b45d1\" at path \"_id\" for model User

So I run npm list command to verify the mongodb and mongoose version in my local. Heres the report: ......
+-- [email protected]
+-- [email protected]

It seems there's an issue on this mongodb version so what I did is I uninstall and try to use different version such as 2.2.16

$ npm uninstall mongodb, it will delete the mongodb from your node_modules directory. After that install the lower version of mongodb.
$ npm install [email protected]
Finally, I restart the app and the CastError is gone!!

How to set session variable in jquery?

You could try using HTML5s sessionStorage it lasts for the duration on the page session. A page session lasts for as long as the browser is open and survives over page reloads and restores. Opening a page in a new tab or window will cause a new session to be initiated.

sessionStorage.setItem("username", "John");

Browser Compatibility compatible with every A-grade browser, included iPhone or Android.

Which regular expression operator means 'Don't' match this character?

[^] ( within [ ] ) is negation in regular expression whereas ^ is "begining of string"

[^a-z] matches any single character that is not from "a" to "z"

^[a-z] means string starts with from "a" to "z"


Set the value of a variable with the result of a command in a Windows batch file

To do what Jesse describes, from a Windows batch file you will need to write:

for /f "delims=" %%a in ('ver') do @set foobar=%%a 

But, I instead suggest using Cygwin on your Windows system if you are used to Unix-type scripting.

How to increase icons size on Android Home Screen?

Unless you write your own Homescreen launcher or use an existing one from Goolge Play, there's "no way" to resize icons.

Well, "no way" does not mean its impossible:

  • As said, you can write your own launcher as discussed in Stackoverflow.
  • You can resize elements on the home screen, but these elements are AppWidgets. Since API level 14 they can be resized and user can - in limits - change the size. But that are Widgets not Shortcuts for launching icons.

Should IBOutlets be strong or weak under ARC?

Be aware, IBOutletCollection should be @property (strong, nonatomic).

How do I find the date a video (.AVI .MP4) was actually recorded?

The existence of that piece of metadata is entirely dependent on the application that wrote the file. It's very common to load up JPG files with metadata (EXIF tags) about the file, such as a timestamp or camera information or geolocation. ID3 tags in MP3 files are also very common. But it's a lot less common to see this kind of metadata in video files.

If you just need a tool to read this data from files manually, GSpot might do the trick:

If you want to read this in code then I imagine each container format is going to have its own standards and each one will take a bit of research and implementation to support.

Change color of PNG image via CSS?

Yes :)

Surfin' Safari - Blog Archive » CSS Masks

WebKit now supports alpha masks in CSS. Masks allow you to overlay the content of a box with a pattern that can be used to knock out portions of that box in the final display. In other words, you can clip to complex shapes based off the alpha of an image.
We have introduced new properties to provide Web designers with a lot of control over these masks and how they are applied. The new properties are analogous to the background and border-image properties that already exist.

-webkit-mask (background)
-webkit-mask-attachment (background-attachment)
-webkit-mask-clip (background-clip)
-webkit-mask-origin (background-origin)
-webkit-mask-image (background-image)
-webkit-mask-repeat (background-repeat)
-webkit-mask-composite (background-composite)
-webkit-mask-box-image (border-image)

Extracting double-digit months and days from a Python date

you can use a string formatter to pad any integer with zeros. It acts just like C's printf.

>>> d =
>>> '%02d' % d.month

Updated for py36: Use f-strings! For general ints you can use the d formatter and explicitly tell it to pad with zeros:

 >>> d =
 >>> f"{d.month:02d}"

But datetimes are special and come with special formatters that are already zero padded:

 >>> f"{d:%d}"  # the day
 >>> f"{d:%m}"  # the month

C# using streams

I would start by reading up on streams on MSDN:

Memorystream and FileStream are streams used to work with raw memory and Files respectively...

Reinitialize Slick js after successful ajax call

The best way is you should destroy the slick slider after reinitializing it.

function slickCarousel() {
    infinite: true,
    slidesToShow: 3,
    slidesToScroll: 1
function destroyCarousel() {
  if ($('.skills_section').hasClass('slick-initialized')) {

  type: 'get',
  url: '/public/index',
  dataType: 'script',
  data: data_send,
  success: function() {

How to configure XAMPP to send mail from localhost?

You can test send mail in Your PC without Internet

you should use Papercut this simple application to test send mail. and you don't need to configure anything.

Just run it and try test send mail:


$to = "[email protected]";
$subject = "My subject";
$txt = "Hello world!";
$headers = "From: [email protected]" . "\r\n" .
"CC: [email protected]";


and you will see this:

enter image description here

I hope you will have a good day. you can find me on Youtube for more tutorial Piseth Sok


Remove duplicated rows using dplyr

For completeness’ sake, the following also works:

df %>% group_by(x) %>% filter (! duplicated(y))

However, I prefer the solution using distinct, and I suspect it’s faster, too.

Servlet for serving static content

There is no need for completely custom implementation of the default servlet in this case, you can use this simple servlet to wrap request to the container's implementation:

package com.example;


import javax.servlet.*;
import javax.servlet.http.*;

public class DefaultWrapperServlet extends HttpServlet
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException
        RequestDispatcher rd = getServletContext().getNamedDispatcher("default");

        HttpServletRequest wrapped = new HttpServletRequestWrapper(req) {
            public String getServletPath() { return ""; }

        rd.forward(wrapped, resp);

How to generate all permutations of a list?

The following code with Python 2.6 and above ONLY

First, import itertools:

import itertools

Permutation (order matters):

print list(itertools.permutations([1,2,3,4], 2))
[(1, 2), (1, 3), (1, 4),
(2, 1), (2, 3), (2, 4),
(3, 1), (3, 2), (3, 4),
(4, 1), (4, 2), (4, 3)]

Combination (order does NOT matter):

print list(itertools.combinations('123', 2))
[('1', '2'), ('1', '3'), ('2', '3')]

Cartesian product (with several iterables):

print list(itertools.product([1,2,3], [4,5,6]))
[(1, 4), (1, 5), (1, 6),
(2, 4), (2, 5), (2, 6),
(3, 4), (3, 5), (3, 6)]

Cartesian product (with one iterable and itself):

print list(itertools.product([1,2], repeat=3))
[(1, 1, 1), (1, 1, 2), (1, 2, 1), (1, 2, 2),
(2, 1, 1), (2, 1, 2), (2, 2, 1), (2, 2, 2)]

What does ==$0 (double equals dollar zero) mean in Chrome Developer Tools?

I will say It 's just shorthand syntax for get reference of html element during debugging time , normaly these kind of task will perform by these method

document.getElementById , document.getElementsByClassName , document.querySelector

so clicking on an html element and getting a reference variable ($0) in console is a huge time saving during the day

How to extract an assembly from the GAC?

One other direction--just unpack the MSI file and get the goodies that way. Saves you from the eventual uninstall . . .

Animate change of view background color on Android

Answer is given in many ways. You can also use ofArgb(startColor,endColor) of ValueAnimator.

for API > 21:

int cyanColorBg = ContextCompat.getColor(this,R.color.cyan_bg);
int purpleColorBg = ContextCompat.getColor(this,R.color.purple_bg);

ValueAnimator valueAnimator = ValueAnimator.ofArgb(cyanColorBg,purpleColorBg);
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
              public void onAnimationUpdate(ValueAnimator valueAnimator) {

Getting the textarea value of a ckeditor textarea with javascript

you can add the following code : the ckeditor field data will be stored in $('#ELEMENT_ID').val() via each click. I've used the method and it works very well. ckeditor field data will be saved realtime and will be ready for sending.


How can I make a TextBox be a "password box" and display stars when using MVVM?

You can make your TextBox as customed PasswordBox by simply adding the following value to FontFamily property of your TextBox control.

    Text="{Binding Password}"

In my case this works perfectly. This will show dot in place of the actual text (not star(*) though).

PowerShell Remoting giving "Access is Denied" error

Had similar problems recently. Would suggest you carefully check if the user you're connecting with has proper authorizations on the remote machine.

You can review permissions using the following command.

Set-PSSessionConfiguration -ShowSecurityDescriptorUI -Name Microsoft.PowerShell

Found this tip here (updated link, thanks "unbob"):

It fixed it for me.

How to call a method in MainActivity from another class?

You can easily call a method from any Fragment inside your Activity by doing a cast like this:




(activity as MainActivity).startChronometer()

Just remember to make sure this Fragment's activity is in fact MainActivity before you do it.

Hope this helps!

how to get current location in google map android

package com.example.sandeep.googlemapsample;

import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;


public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
        View.OnClickListener {

    private static final String TAG = "MapsActivity";
    private GoogleMap mMap;
    private double longitude;
    private double latitude;
    private GoogleApiClient googleApiClient;

    protected void onCreate(Bundle savedInstanceState) {

        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()

        //Initializing googleApiClient
        googleApiClient = new GoogleApiClient.Builder(this)

    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
       // googleMapOptions.mapType(googleMap.MAP_TYPE_HYBRID)
                    //    .compassEnabled(true);

        // Add a marker in Sydney and move the camera
        LatLng india = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(india).title("Marker in India"));

    //Getting current location
    private void getCurrentLocation() {
        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
        Location location = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);
        if (location != null) {
            //Getting longitude and latitude
            longitude = location.getLongitude();
            latitude = location.getLatitude();

            //moving the map to location

    private void moveMap() {
         * Creating the latlng object to store lat, long coordinates
         * adding marker to map
         * move the camera with animation
        LatLng latLng = new LatLng(latitude, longitude);
        mMap.addMarker(new MarkerOptions()
                .title("Marker in India"));



    public void onClick(View view) {
        Log.v(TAG,"view click event");

    public void onConnected(@Nullable Bundle bundle) {

    public void onConnectionSuspended(int i) {


    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {


    public void onMapLongClick(LatLng latLng) {
        // mMap.clear();
        mMap.addMarker(new MarkerOptions().position(latLng).draggable(true));

    public void onMarkerDragStart(Marker marker) {
        Toast.makeText(MapsActivity.this, "onMarkerDragStart", Toast.LENGTH_SHORT).show();

    public void onMarkerDrag(Marker marker) {
        Toast.makeText(MapsActivity.this, "onMarkerDrag", Toast.LENGTH_SHORT).show();

    public void onMarkerDragEnd(Marker marker) {
        // getting the Co-ordinates
        latitude = marker.getPosition().latitude;
        longitude = marker.getPosition().longitude;

        //move to current position

    protected void onStart() {

    protected void onStop() {

    public boolean onMarkerClick(Marker marker) {
        Toast.makeText(MapsActivity.this, "onMarkerClick", Toast.LENGTH_SHORT).show();
        return true;


How can I start PostgreSQL server on Mac OS X?

If you installed PostgreSQL using the EnterpriseDB installer, then what Kenial suggested is the way to go:

sudo -u postgres pg_ctl -D /Library/PostgreSQL/{version}/data start
sudo -u postgres pg_ctl -D /Library/PostgreSQL/{version}/data stop

Linux bash: Multiple variable assignment

I think this might help...

In order to break down user inputted dates (mm/dd/yyyy) in my scripts, I store the day, month, and year into an array, and then put the values into separate variables as follows:

DATE_ARRAY=(`echo $2 | sed -e 's/\// /g'`)
MONTH=(`echo ${DATE_ARRAY[0]}`)
DAY=(`echo ${DATE_ARRAY[1]}`)
YEAR=(`echo ${DATE_ARRAY[2]}`)

5.7.57 SMTP - Client was not authenticated to send anonymous mail during MAIL FROM error

Main two reasons only as mentioned in above comments

  1. NetworkCredentials you set should be correct. Verify with try actually signing into the account.
  2. You need to set UseDefaultCredentials to false first and then set Credentials Or Put smtp.UseDefaultCredentials = false; above the smtp.Credentials assignment.

Notepad++ Multi editing

In the position where you want to add text, do:

Shift + Alt + down arrow

and select the lines you want. Then type. The text you type is inserted on all of the lines you selected.

Swift performSelector:withObject:afterDelay: is unavailable

You could do this:

var timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: Selector("someSelector"), userInfo: nil, repeats: false)

func someSelector() {
    // Something after a delay


let timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(someSelector), userInfo: nil, repeats: false)

func someSelector() {
    // Something after a delay

What does the question mark and the colon (?: ternary operator) mean in objective-c?

Ternary operator example.If the value of isFemale boolean variable is YES, print "GENDER IS FEMALE" otherwise "GENDER IS MALE"

? means = execute the codes before the : if the condition is true. 
: means = execute the codes after the : if the condition is false.


BOOL isFemale = YES;
NSString *valueToPrint = (isFemale == YES) ? @"GENDER IS FEMALE" : @"GENDER IS MALE";
NSLog(valueToPrint); //Result will be "GENDER IS FEMALE" because the value of isFemale was set to YES.

For Swift

let isFemale = false
let valueToPrint:String = (isFemale == true) ? "GENDER IS FEMALE" : "GENDER IS MALE"
print(valueToPrint) //Result will be  "GENDER IS MALE" because the isFemale value was set to false.

How do I get sed to read from standard input?

use the --expression option

grep searchterm myfile.csv | sed --expression='s/replaceme/withthis/g'

Bootstrap - dropdown menu not working?

put following code in your page

    function EndRequest(sender, args) {
        if (args.get_error() == undefined) {

Virtual Serial Port for Linux

I can think of three options:

Implement RFC 2217

RFC 2217 covers a com port to TCP/IP standard that allows a client on one system to emulate a serial port to the local programs, while transparently sending and receiving data and control signals to a server on another system which actually has the serial port. Here's a high-level overview.

What you would do is find or implement a client com port driver that would implement the client side of the system on your PC - appearing to be a real serial port but in reality shuttling everything to a server. You might be able to get this driver for free from Digi, Lantronix, etc in support of their real standalone serial port servers.

You would then implement the server side of the connection locally in another program - allowing the client to connect and issuing the data and control commands as needed.

It's probably non trivial, but the RFC is out there, and you might be able to find an open source project that implements one or both sides of the connection.

Modify the linux serial port driver

Alternately, the serial port driver source for Linux is readily available. Take that, gut the hardware control pieces, and have that one driver run two /dev/ttySx ports, as a simple loopback. Then connect your real program to the ttyS2 and your simulator to the other ttySx.

Use two USB<-->Serial cables in a loopback

But the easiest thing to do right now? Spend $40 on two serial port USB devices, wire them together (null modem) and actually have two real serial ports - one for the program you're testing, one for your simulator.


How to add double quotes to a string that is inside a variable?

If I understand your question properly, maybe you can try this:

string title = string.Format("<div>\"{0}\"</div>", "some text");

How can I dismiss the on screen keyboard?

You can also declare a focusNode for you textfield and when you are done you can just call the unfocus method on that focusNode and also dispose it

class MyHomePage extends StatefulWidget {
  MyHomePageState createState() => new MyHomePageState();

class MyHomePageState extends State<MyHomePage> {
  TextEditingController _controller = new TextEditingController();

/// declare focus
  final FocusNode _titleFocus = FocusNode();

  void dispose() {

  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.send),
        onPressed: () {
          setState(() {
            // send message
            // dismiss on screen keyboard here

      body: new Container(
        padding: new EdgeInsets.all(20.0),
        child: new TextFormField(
          controller: _controller,
          focusNode: _titleFocus,
          decoration: new InputDecoration(labelText: 'Example Text'),

How to force Laravel Project to use HTTPS for all routes?

Add this to your .htaccess code

RewriteEngine On 
RewriteCond %{SERVER_PORT} 80 
RewriteRule ^(.*)$$1 [R,L]

Replace with your domain name. This will force all the urls of your domain to use https. Make sure you have https certificate installed and configured on your domain. If you do not see https in green as secure, press f12 on chrome and fix all the mixed errors in the console tab.

Hope this helps!

How to add custom Http Header for C# Web Service Client consuming Axis 1.4 Web service

I find this code and is resolve my problem.

protected override WebRequest GetWebRequest(Uri uri)
    // Assuming authValue is set from somewhere, such as the config file
    HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(uri);
    request.Headers.Add("Authorization", string.Format("Basic {0}", authValue));
    return request;

Where Is Machine.Config?

In order to be absolutely sure, slap a Label on an ASP.NET page and run this code:

labelDebug.Text = System.Runtime.InteropServices.RuntimeEnvironment.SystemConfigurationFile;

I believe this will leave no doubt!

How do you set the title color for the new Toolbar?

Do it with toolbar.setTitleTextAppearance(context,;

//this is style where you can customize your color scheme

 <style name="TitleTextStyle" parent="@android:style/TextAppearance.Holo.Widget.ActionBar.Title">
    <item name="android:fontFamily">@string/you_font_family</item>
    <item name="android:textStyle">normal</item>
    <item name="android:textAppearance">@style/you_text_style</item>
    <item name="android:textColor">#000000</item>
    <item name="android:textSize">20sp</item>

Understanding generators in Python

A generator is effectively a function that returns (data) before it is finished, but it pauses at that point, and you can resume the function at that point.

>>> def myGenerator():
...     yield 'These'
...     yield 'words'
...     yield 'come'
...     yield 'one'
...     yield 'at'
...     yield 'a'
...     yield 'time'

>>> myGeneratorInstance = myGenerator()
>>> next(myGeneratorInstance)
>>> next(myGeneratorInstance)

and so on. The (or one) benefit of generators is that because they deal with data one piece at a time, you can deal with large amounts of data; with lists, excessive memory requirements could become a problem. Generators, just like lists, are iterable, so they can be used in the same ways:

>>> for word in myGeneratorInstance:
...     print word

Note that generators provide another way to deal with infinity, for example

>>> from time import gmtime, strftime
>>> def myGen():
...     while True:
...         yield strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime())    
>>> myGeneratorInstance = myGen()
>>> next(myGeneratorInstance)
Thu, 28 Jun 2001 14:17:15 +0000
>>> next(myGeneratorInstance)
Thu, 28 Jun 2001 14:18:02 +0000   

The generator encapsulates an infinite loop, but this isn't a problem because you only get each answer every time you ask for it.

How to validate domain name in PHP?

This is validation of domain name in javascript:

function frmValidate() {
 if (/^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9](?:\.[a-zA-Z]{2,})+$/.test(val)){
      alert("Valid Domain Name");
      return true;
 } else {
      alert("Enter Valid Domain Name");;
      return false;

Align DIV to bottom of the page

Simple 2020 no-tricks method:

body {
    display: flex;
    flex-direction: column;

#footer {
    margin-top: auto;

How do I find what Java version Tomcat6 is using?

You can use the Tomcat manager app to find out which JRE and OS versions Tomcat is using. Given a user tomcat with password password with a role of manager:

Tomcat 6:

curl http://tomcat:password@localhost:8080/manager/serverinfo

Tomcat 7/8:

curl http://tomcat:password@localhost:8080/manager/text/serverinfo

Windows command to get service status?

Ros the code i post also is for knowing how many services are running...

Imagine you want to know how many services are like Oracle* then you put Oracle instead of NameOfSercive... and you get the number of services like Oracle* running on the variable %CountLines% and if you want to do something if there are only 4 you can do something like this:

IF 4==%CountLines% GOTO FourServicesAreRunning

That is much more powerfull... and your code does not let you to know if desired service is running ... if there is another srecive starting with same name... imagine: -ServiceOne -ServiceOnePersonal

If you search for ServiceOne, but it is only running ServiceOnePersonal your code will tell ServiceOne is running...

My code can be easly changed, since it reads all lines of the file and read line by line it can also do whatever you want to each service... see this:

REM Put here any code to be run before check for Services

SET TemporalFile=TemporalFile.TXT
NET START > %TemporalFile%
SET CountLines=0
FOR /F "delims=" %%X IN (%TemporalFile%) DO SET /A CountLines=1+CountLines
SETLOCAL EnableDelayedExpansion
SET CountLine=0
FOR /F "delims=" %%X IN (%TemporalFile%) DO @(
 SET /A CountLine=1+CountLine

 REM Do whatever you want to each line here, remember first and last are special not service names

 IF 1==!CountLine! (

   REM Do whatever you want with special first line, not a service.

 ) ELSE IF %CountLines%==!CountLine! (

   REM Do whatever you want with special last line, not a service.

 ) ELSE (

   REM Do whatever you want with rest lines, for each service.
   REM    For example echo its position number and name:

   echo !CountLine! - %%X

   REM    Or filter by exact name (do not forget to not remove the three spaces at begining):
   IF "   NameOfService"=="%%X" (

     REM Do whatever you want with Service filtered.


 REM Do whatever more you want to all lines here, remember two first are special as last one


DEL -P %TemporalFile% 2>nul
SET TemporalFile=

REM Put here any code to be run after check for Services

Of course it only list running services, i do not know any way net can list not running services...

Hope this helps!!!

What is time(NULL) in C?

You can pass in a pointer to a time_t object that time will fill up with the current time (and the return value is the same one that you pointed to). If you pass in NULL, it just ignores it and merely returns a new time_t object that represents the current time.

Nb:time(&timer); is equivalent to timer = time(NULL);

How to call servlet through a JSP page

there isn't method to call Servlet. You should make mapping in web.xml and then trigger this mapping.

Example: web.xml:



This mapping means that every call to http://yoursite/yourwebapp/hello trigger this servlet For example this jsp:

<jsp:forward page="/hello"/> 

How to save an activity state using save instance state?

My colleague wrote an article explaining application state on Android devices including explanations on activity lifecycle and state information, how to store state information, and saving to state Bundle and SharedPreferences and take a look at here.

The article covers three approaches:

Store local variable/UI control data for application lifetime (i.e. temporarily) using an instance state bundle

[Code sample – Store state in state bundle]
public void onSaveInstanceState(Bundle savedInstanceState)
  // Store UI state to the savedInstanceState.
  // This bundle will be passed to onCreate on next call.  EditText txtName = (EditText)findViewById(;
  String strName = txtName.getText().toString();

  EditText txtEmail = (EditText)findViewById(;
  String strEmail = txtEmail.getText().toString();

  CheckBox chkTandC = (CheckBox)findViewById(;
  boolean blnTandC = chkTandC.isChecked();

  savedInstanceState.putString(“Name”, strName);
  savedInstanceState.putString(“Email”, strEmail);
  savedInstanceState.putBoolean(“TandC”, blnTandC);


Store local variable/UI control data between application instances (i.e. permanently) using shared preferences

[Code sample – store state in SharedPreferences]
protected void onPause()

  // Store values between instances here
  SharedPreferences preferences = getPreferences(MODE_PRIVATE);
  SharedPreferences.Editor editor = preferences.edit();  // Put the values from the UI
  EditText txtName = (EditText)findViewById(;
  String strName = txtName.getText().toString();

  EditText txtEmail = (EditText)findViewById(;
  String strEmail = txtEmail.getText().toString();

  CheckBox chkTandC = (CheckBox)findViewById(;
  boolean blnTandC = chkTandC.isChecked();

  editor.putString(“Name”, strName); // value to store
  editor.putString(“Email”, strEmail); // value to store
  editor.putBoolean(“TandC”, blnTandC); // value to store
  // Commit to storage

Keeping object instances alive in memory between activities within application lifetime using a retained non-configuration instance

[Code sample – store object instance]
private cMyClassType moInstanceOfAClass; // Store the instance of an object
public Object onRetainNonConfigurationInstance()
  if (moInstanceOfAClass != null) // Check that the object exists
  return super.onRetainNonConfigurationInstance();

Add php variable inside echo statement as href link address?

You can use one and more echo statement inside href

<a href="profile.php?usr=<?php echo $_SESSION['firstname']."&email=". $_SESSION['email']; ?> ">Link</a>

link : "/profile.php?usr=firstname&email=email"

Joining two lists together

Something like this:

firstList.AddRange (secondList);

Or, you can use the 'Union' extension method that is defined in System.Linq. With 'Union', you can also specify a comparer, which can be used to specify whether an item should be unioned or not.

Like this:

List<int> one = new List<int> { 1, 2, 3, 4, 5 };
List<int> second=new List<int> { 1, 2, 5, 6 };

var result = one.Union (second, new EqComparer ());

foreach( int x in result )
    Console.WriteLine (x);
Console.ReadLine ();

#region IEqualityComparer<int> Members
public class EqComparer : IEqualityComparer<int>
    public bool Equals( int x, int y )
        return x == y;

    public int GetHashCode( int obj )
        return obj.GetHashCode ();

Using Cygwin to Compile a C program; Execution error

This file (cygwin1.dll) is cygwin dependency similar to qt must copy this file and similar files that appear in such messages error, from "cygwin/bin" to folder of the your program .Also this is necessary to run in another computer that have NOT cygwin!

Converting PKCS#12 certificate into PEM using OpenSSL

If you can use Python, it is even easier if you have the pyopenssl module. Here it is:

from OpenSSL import crypto

# May require "" for empty password depending on version

with open("push.p12", "rb") as file:
    p12 = crypto.load_pkcs12(, "my_passphrase")

# PEM formatted private key
print crypto.dump_privatekey(crypto.FILETYPE_PEM, p12.get_privatekey())

# PEM formatted certificate
print crypto.dump_certificate(crypto.FILETYPE_PEM, p12.get_certificate())

Insert all values of a table into another table in SQL

The insert statement actually has a syntax for doing just that. It's a lot easier if you specify the column names rather than selecting "*" though:

INSERT INTO new_table (Foo, Bar, Fizz, Buzz)
SELECT Foo, Bar, Fizz, Buzz
FROM initial_table
-- optionally WHERE ...

I'd better clarify this because for some reason this post is getting a few down-votes.

The INSERT INTO ... SELECT FROM syntax is for when the table you're inserting into ("new_table" in my example above) already exists. As others have said, the SELECT ... INTO syntax is for when you want to create the new table as part of the command.

You didn't specify whether the new table needs to be created as part of the command, so INSERT INTO ... SELECT FROM should be fine if your destination table already exists.

How to remove td border with html?

To remove borders between cells, while retaining the border around the table, add the attribute rules=none to the table tag.

There is no way in HTML to achieve the rendering specified in the last figure of the question. There are various tricky workarounds that are based on using some other markup structure.

How to dynamically add elements to String array?

when using String array, you have to give size of array while initializing


String[] str = new String[10];

you can use index 0-9 to store values

str[0] = "value1"
str[1] = "value2"
str[2] = "value3"
str[3] = "value4"
str[4] = "value5"
str[5] = "value6"
str[6] = "value7"
str[7] = "value8"
str[8] = "value9"
str[9] = "value10"

if you are using ArrayList instread of string array, you can use it without initializing size of array ArrayList str = new ArrayList();

you can add value by using add method of Arraylist


get retrieve a value from arraylist, you can use get method

String s = str.get(0);

find total number of items by size method

int nCount = str.size();

read more from here

ORA-00972 identifier is too long alias column name

I'm using Argos reporting system as a front end and Oracle in back. I just encountered this error and it was caused by a string with a double quote at the start and a single quote at the end. Replacing the double quote with a single solved the issue.

When to use LinkedList over ArrayList in Java?

I have read the responses, but there is one scenario where I always use a LinkedList over an ArrayList that I want to share to hear opinions:

Every time I had a method that returns a list of data obtained from a DB I always use a LinkedList.

My rationale was that because it is impossible to know exactly how many results am I getting, there will be not memory wasted (as in ArrayList with the difference between the capacity and actual number of elements), and there would be no time wasted trying to duplicate the capacity.

As far a ArrayList, I agree that at least you should always use the constructor with the initial capacity, to minimize the duplication of the arrays as much as possible.

A generic error occurred in GDI+, JPEG Image to MemoryStream

I'll add this cause of the error as well in hopes it helps some future internet traveler. :)

GDI+ limits the maximum height of an image to 65500

We do some basic image resizing, but in resizing we try to maintain aspect ratio. We have a QA guy who's a little too good at this job; he decided to test this with a ONE pixel wide photo that was 480 pixels tall. When the image was scaled to meet our dimensions, the height was north of 68,000 pixels and our app exploded with A generic error occurred in GDI+.

You can verify this yourself with test:

  int width = 480;
  var height = UInt16.MaxValue - 36; //succeeds at 65499, 65500
      var image = new Bitmap(width, height);
      using(MemoryStream ms = new MemoryStream())
        //error will throw from here
        image.Save(ms, ImageFormat.Jpeg);
      height += 1;
  catch(Exception ex)
    //explodes at 65501 with "A generic error occurred in GDI+."

It's too bad there's not a friendly .net ArgumentException thrown in the constructor of Bitmap.

How to use multiple conditions (With AND) in IIF expressions in ssrs

You don't need an IIF() at all here. The comparisons return true or false anyway.

Also, since this row visibility is on a group row, make sure you use the same aggregate function on the fields as you use in the fields in the row. So if your group row shows sums, then you'd put this in the Hidden property.

=Sum(Fields!OpeningStock.Value) = 0 And
Sum(Fields!GrossDispatched.Value) = 0 And 
Sum(Fields!TransferOutToMW.Value) = 0 And
Sum(Fields!TransferOutToDW.Value) = 0 And
Sum(Fields!TransferOutToOW.Value) = 0 And
Sum(Fields!NetDispatched.Value) = 0 And
Sum(Fields!QtySold.Value) = 0 And
Sum(Fields!StockAdjustment.Value) = 0 And
Sum(Fields!ClosingStock.Value) = 0

But with the above version, if one record has value 1 and one has value -1 and all others are zero then sum is also zero and the row could be hidden. If that's not what you want you could write a more complex expression:

        Fields!OpeningStock.Value=0 AND
        Fields!GrossDispatched.Value=0 AND
        Fields!TransferOutToMW.Value=0 AND
        Fields!TransferOutToDW.Value=0 AND 
        Fields!TransferOutToOW.Value=0 AND
        Fields!NetDispatched.Value=0 AND
        Fields!QtySold.Value=0 AND
        Fields!StockAdjustment.Value=0 AND
) = 0

This is essentially a fancy way of counting the number of rows in which any field is not zero. If every field is zero for every row in the group then the expression returns true and the row is hidden.

Live-stream video from one android phone to another over WiFi

If you do not need the recording and playback functionality in your app, using off-the-shelf streaming app and player is a reasonable choice.

If you do need them to be in your app, however, you will have to look into MediaRecorder API (for the server/camera app) and MediaPlayer (for client/player app).

Quick sample code for the server:

// this is your network socket
ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket);
mCamera = getCameraInstance();
mMediaRecorder = new MediaRecorder();
// this is the unofficially supported MPEG2TS format, suitable for streaming (Android 3.0+)

On the player side it is a bit tricky, you could try this:

// this is your network socket, connected to the server
ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket);
mMediaPlayer = new MediaPlayer();

Unfortunately mediaplayer tends to not like this, so you have a couple of options: either (a) save data from socket to file and (after you have a bit of data) play with mediaplayer from file, or (b) make a tiny http proxy that runs locally and can accept mediaplayer's GET request, reply with HTTP headers, and then copy data from the remote server to it. For (a) you would create the mediaplayer with a file path or file url, for (b) give it a http url pointing to your proxy.

See also:

Stream live video from phone to phone using socket fd

MediaPlayer stutters at start of mp3 playback

Change R default library path using .libPaths in fails to work

If you do not have admin-rights, it can also be helpful to open the located in \R-3.1.0\etc and add:

.First <- function(){
  .libPaths("your path here")

This evaluates the .libPath() command directly at start

console.log(result) returns [object Object]. How do I get

Use console.log(JSON.stringify(result)) to get the JSON in a string format.

EDIT: If your intention is to get the id and other properties from the result object and you want to see it console to know if its there then you can check with hasOwnProperty and access the property if it does exist:

var obj = {id : "007", name : "James Bond"};
console.log(obj);                    // Object { id: "007", name: "James Bond" }
console.log(JSON.stringify(obj));    //{"id":"007","name":"James Bond"}
if (obj.hasOwnProperty("id")){
    console.log(;             //007

How do I use CMake?

CMake (Cross platform make) is a build system generator. It doesn't build your source, instead, generates what a build system needs: the build scripts. Doing so you don't need to write or maintain platform specific build files. CMake uses relatively high level CMake language which usually written in CMakeLists.txt files. Your general workflow when consuming third party libraries usually boils down the following commands:

cmake -S thelibrary -B build
cmake --build build
cmake --install build

The first line known as configuration step, this generates the build files on your system. -S(ource) is the library source, and -B(uild) folder. CMake falls back to generate build according to your system. it will be MSBuild on Windows, GNU Makefiles on Linux. You can specify the build using -G(enerator) paramater, like:

cmake -G Ninja -S libSource -B build

end of the this step, generates build scripts, like Makefile, *.sln files etc. on build directory.

The second line invokes the actual build command, it's like invoking make on the build folder.

The third line install the library. If you're on Windows, you can quickly open generated project by, cmake --open build.

Now you can use the installed library on your project with configured by CMake, writing your own CMakeLists.txt file. To do so, you'll need to create a your target and find the package you installed using find_package command, which will export the library target names, and link them against your own target.

Variables declared outside function

The local names for a function are decided when the function is defined:

>>> x = 1
>>> def inc():
...     x += 5
>>> inc.__code__.co_varnames

In this case, x exists in the local namespace. Execution of x += 5 requires a pre-existing value for x (for integers, it's like x = x + 5), and this fails at function call time because the local name is unbound - which is precisely why the exception UnboundLocalError is named as such.

Compare the other version, where x is not a local variable, so it can be resolved at the global scope instead:

>>> def incg():
...    print(x)
>>> incg.__code__.co_varnames

Similar question in faq:

How do I set a column value to NULL in SQL Server Management Studio?

CTRL+0 doesn't seem to work when connected to an Azure DB.

However, to create an empty string, you can always just hit 'anykey then delete' inside a cell.

How to unpublish an app in Google Play Developer Console

As per new Interface follow these steps

  1. Go to Google Play Developer Console
  2. Select your app you want to un-publish
  3. From the left Navigation Release >> Setup >> Advance Settings
  4. In the App Availability Check on Unpublished Radio button enter image description here

HTML Table different number of columns in different rows


      <td> Row 1 Col 1</td>
      <td> Row 1 Col 2</td>
      <td colspan=2> Row 2 Long Col</td>

How to open a new tab using Selenium WebDriver

The same example for Node.js:

var webdriver = require('selenium-webdriver');
driver = new webdriver.Builder().
driver.findElement(webdriver.By.tagName("body")).sendKeys(webdriver.Key.COMMAND + "t");

How to keep the local file or the remote file during merge using Git and the command line?

git checkout {branch-name} -- {file-name}

This will use the file from the branch of choice.

I like this because posh-git autocomplete works great with this. It also removes any ambiguity as to which branch is remote and which is local. And --theirs didn't work for me anyways.

Adding values to Arraylist

Actually, a third is preferred:

ArrayList<Object> array = new ArrayList<Object>();

This avoids autoboxing (Integer.valueOf(3) versus 3) and doesn't create an unnecessary String object.

Eclipse complains when you don't use type arguments with a generic type like ArrayList, because you are using something called a raw type, which is discouraged. If a class is generic (that is, it has type parameters), then you should always use type arguments with that class.

Autoboxing, on the other hand, is a personal preference. Some people are okay with it, and some not. I don't like it, and I turn on the warning for autoboxing/autounboxing.

System not declared in scope?

You need to add:

 #include <cstdlib>

in order for the compiler to see the prototype for system().

open read and close a file in 1 line of code

No need to import any special libraries to do this.

Use normal syntax and it will open the file for reading then close it.

with open("/etc/hostname","r") as f: print 


with open("/etc/hosts","r") as f: x =

which gives you an array x containing the lines, and can be printed like so:

for line in x: print line

These one-liners are very helpful for maintenance - basically self-documenting.

Package php5 have no installation candidate (Ubuntu 16.04)

If you just want to install PHP no matter what version it is, try PHP7

sudo apt-get install php7.0 php7.0-mcrypt

Imported a csv-dataset to R but the values becomes factors

Both the data import function (here: read.csv()) as well as a global option offer you to say stringsAsFactors=FALSE which should fix this.

Failed to build gem native extension (installing Compass)

Try this, then try to install compass again

apt-get install ruby-dev

CSS-moving text from left to right

Somehow I got it to work by using margin-right, and setting it to move from right to left.

Don't know why for this case, margin-right 100% doesn't go off the screen. :D (tested on chrome 18)

EDIT: now left to right works too

How do I simulate a low bandwidth, high latency environment?

Try WANem

WANem is a Wide Area Network Emulator, meant to provide a real experience of a Wide Area Network/Internet, during application development / testing over a LAN environment.

Oracle PL/SQL - How to create a simple array variable?

Another solution is to use an Oracle Collection as a Hashmap:

-- create a type for your "Array" - it can be of any kind, record might be useful
  type hash_map is table of varchar2(1000) index by varchar2(30);
  my_hmap hash_map ;
-- i will be your iterator: it must be of the index's type
  i varchar2(30);
  my_hmap('a') := 'apple';
  my_hmap('b') := 'box';
  my_hmap('c') := 'crow';
-- then how you use it:

  dbms_output.put_line (my_hmap('c')) ;

-- or to loop on every element - it's a "collection"
  i := my_hmap.FIRST;

  while (i is not null)  loop     
    i := my_hmap.NEXT(i);
  end loop;


How do I open an .exe from another C++ .exe?

You are getting this error because you are not giving full path. (C:\Users...\file.exe) If you want to remove this error then either give full path or copy that application (you want to open) to the folder where your project(.exe) is present/saved.

#include <windows.h>
using namespace std;
int main()
  system ("start C:\\Users\\Folder\\chrome.exe"); //for opening stackoverflow through google chrome , if chorme.exe is in that folder..
  return 0;

Setting Android Theme background color

Okay turned out that I made a really silly mistake. The device I am using for testing is running Android 4.0.4, API level 15.

The styles.xml file that I was editing is in the default values folder. I edited the styles.xml in values-v14 folder and it works all fine now.

Collision resolution in Java HashMap

First of all, you have got the concept of hashing a little wrong and it had been rectified by Mr. Sanjay.

And yes, Java indeed implement a collision resolution technique. When two keys get hashed to a same value (as the internal array used is finite in size and at some point the hashcode() method will return same hash value for two different keys) at this time, a linked list is formed at the bucket location where all the informations are entered as an Map.Entry object that contains a key-value pair. Accessing an object via a key will at worst require O(n) if the entry in present in such a lists. Comparison between the key you passed with each key in such list will be done by the equals() method.

Although, from Java 8 , the linked lists are replaced with trees (O(log n))

Jenkins could not run git

Also you can set Git location in Jenkins server/node configuration:

goto Configure, under section Node Properties mark checkbox Tools Location and set yours path to Git.

enter image description here

bash, extract string before a colon

This works for me you guys can try it out

SUBSTRING=$(echo $INPUT| cut -d: -f1)

How do you send an HTTP Get Web Request in Python?

In Python, you can use urllib2 ( to do all of that work for you.

Simply enough:

import urllib2
f =  urllib2.urlopen(url)

Will print the received HTTP response.

To pass GET/POST parameters the urllib.urlencode() function can be used. For more information, you can refer to the Official Urllib2 Tutorial

Assembly Language - How to do Modulo?

If you compute modulo a power of two, using bitwise AND is simpler and generally faster than performing division. If b is a power of two, a % b == a & (b - 1).

For example, let's take a value in register EAX, modulo 64.
The simplest way would be AND EAX, 63, because 63 is 111111 in binary.

The masked, higher digits are not of interest to us. Try it out!

Analogically, instead of using MUL or DIV with powers of two, bit-shifting is the way to go. Beware signed integers, though!

How can I add a variable to console.log?

You can also use printf style of formatting arguments. It is available in at least Chrome, Firefox/Firebug and node.js.

var name = prompt("what is your name?");

console.log("story %s story", name);

It also supports %d for formatting numbers

How do I convert NSMutableArray to NSArray?

An NSMutableArray is a subclass of NSArray so you won't always need to convert but if you want to make sure that the array can't be modified you can create a NSArray either of these ways depending on whether you want it autoreleased or not:

/* Not autoreleased */
NSArray *array = [[NSArray alloc] initWithArray:mutableArray];

/* Autoreleased array */
NSArray *array = [NSArray arrayWithArray:mutableArray];

EDIT: The solution provided by Georg Schölly is a better way of doing it and a lot cleaner, especially now that we have ARC and don't even have to call autorelease.

Using classes with the Arduino

On this page, the Arduino sketch defines a couple of Structs (plus a couple of methods) which are then called in the setup loop and main loop. Simple enough to interpret, even for a barely-literate programmer like me.

Trying to handle "back" navigation button action in iOS

Perhaps this answers doesn't fit your explanation but question title. It's useful when you are trying to know when you tapped the back button on an UINavigationBar.

In this case you can use UINavigationBarDelegate protocol and implement one of this methods:

- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item;
- (void)navigationBar:(UINavigationBar *)navigationBar didPopItem:(UINavigationItem *)item;

When didPopItem method is called, it's because you either tapped the back button or you used [UINavigationBar popNavigationItemAnimated:] method and the navigation bar did pop the item.

Now, if you want to know what action triggered the didPopItem method you can use a flag.

With this approach I don't need to manually add a left bar button item with an arrow image in order to make it similar to iOS back button, and be able to set my custom target/action.

Let's see an example:

I have a view controller that has a page view controller, and a custom page indicator view. I'm also using a custom UINavigationBar to display a title to know on what page am I and the back button to go back to the previous page. And I also can swipe to previous/next page on page controller.

#pragma mark - UIPageViewController Delegate Methods
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed {

    if( completed ) {


        if( currentIndex > lastIndex ) {

            UINavigationItem *navigationItem = [[UINavigationItem alloc] initWithTitle:@"Some page title"];

            [[_someViewController navigationBar] pushNavigationItem:navigationItem animated:YES];
            [[_someViewController pageControl] setCurrentPage:currentIndex];
        } else {
            _autoPop = YES; //We pop the item automatically from code.
            [[_someViewController navigationBar] popNavigationItemAnimated:YES];
            [[_someViewController pageControl] setCurrentPage:currentIndex];


So then I implement UINavigationBar delegate methods:

#pragma mark - UINavigationBar Delegate Methods
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {
    if( !_autoPop ) {
        //Pop by back button tap
    } else {
        //Pop from code

    _autoPop = NO;

    return YES;

In this case I used shouldPopItem because the pop is animated and I wanted to handle the back button immediately and not to wait until transition is finished.

Call Javascript function from URL/address bar

There isn't from a hyperlink, no. Not unless the page has script inside specifically for this and it's checking for some parameter....but for your question, no, there's no built-in support in browsers for this.

There are however bookmarklets you can bookmark to quickly run JavaScript functions from your address bar; not sure if that meets your needs, but it's as close as it gets.

APT command line interface-like yes/no input?

A very simple (but not very sophisticated) way of doing this for a single choice would be:

msg = 'Shall I?'
shall = input("%s (y/N) " % msg).lower() == 'y'

You could also write a simple (slightly improved) function around this:

def yn_choice(message, default='y'):
    choices = 'Y/n' if default.lower() in ('y', 'yes') else 'y/N'
    choice = input("%s (%s) " % (message, choices))
    values = ('y', 'yes', '') if choices == 'Y/n' else ('y', 'yes')
    return choice.strip().lower() in values

Note: On Python 2, use raw_input instead of input.

How to use bootstrap-theme.css with bootstrap 3?

Bootstrap-theme.css is the additional CSS file, which is optional for you to use. It gives 3D effects on the buttons and some other elements.

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

I would comment if i could , but i have no permissions yet, so i will post a hint as an answer, for unexpected behavior on some android devices:

Position: Fixed only works in Android 2.1 thru 2.3 by using the following meta tag:

<meta name="viewport" content="width=device-width, user-scalable=no">.


PHP salt and hash SHA256 for login password

You can't do that because you can not know the salt at a precise time. Below, a code who works in theory (not tested for the syntaxe)

$password1 = $_POST['password'];
$salt      = 'hello_1m_@_SaLT';
$hashed    = hash('sha256', $password1 . $salt);

When you insert :

$qry="INSERT INTO member VALUES('$username', '$hashed')";

And for retrieving user :

$qry="SELECT * FROM member WHERE username='$username' AND password='$hashed'";

"python" not recognized as a command

Further to @Udi post this is what the script tried to do, but did not work with me.

I had to the set the following in the PATH nothing else.


Were mine and now python works in the cmd

Is there any way to return HTML in a PHP function? (without building the return value as a string)

Yes, there is: you can capture the echoed text using ob_start:

<?php function TestBlockHTML($replStr) {
    ob_start(); ?>
    <body><h1><?php echo($replStr) ?></h1>
    return ob_get_clean();
} ?>

How to nicely format floating numbers to string without unnecessary decimal 0's

This is what I came up with:

  private static String format(final double dbl) {
    return dbl % 1 != 0 ? String.valueOf(dbl) : String.valueOf((int) dbl);

It is a simple one-liner and only casts to int if it really needs to.

IIS7 Permissions Overview - ApplicationPoolIdentity

I fixed all my problems simply by creating a new user called IUSER with a password and added it the Network Service and User Groups. Then create all your virtual sites and applications set authentication to IUSER with its password.. set high level file access to include IUSER and BAM it fixed at least 3-4 issues including this one..


Drop Down Menu/Text Field in one

I like jQuery Token input. Actually prefer the UI over some of the other options mentioned above.

Also see: for an explanation

Tkinter: How to use threads to preventing main event loop from "freezing"

I will submit the basis for an alternate solution. It is not specific to a Tk progress bar per se, but it can certainly be implemented very easily for that.

Here are some classes that allow you to run other tasks in the background of Tk, update the Tk controls when desired, and not lock up the gui!

Here's class TkRepeatingTask and BackgroundTask:

import threading

class TkRepeatingTask():

    def __init__( self, tkRoot, taskFuncPointer, freqencyMillis ):
        self.__tk_   = tkRoot
        self.__func_ = taskFuncPointer        
        self.__freq_ = freqencyMillis
        self.__isRunning_ = False

    def isRunning( self ) : return self.__isRunning_ 

    def start( self ) : 
        self.__isRunning_ = True

    def stop( self ) : self.__isRunning_ = False

    def __onTimer( self ): 
        if self.__isRunning_ :
            self.__tk_.after( self.__freq_, self.__onTimer )

class BackgroundTask():

    def __init__( self, taskFuncPointer ):
        self.__taskFuncPointer_ = taskFuncPointer
        self.__workerThread_ = None
        self.__isRunning_ = False

    def taskFuncPointer( self ) : return self.__taskFuncPointer_

    def isRunning( self ) : 
        return self.__isRunning_ and self.__workerThread_.isAlive()

    def start( self ): 
        if not self.__isRunning_ :
            self.__isRunning_ = True
            self.__workerThread_ = self.WorkerThread( self )

    def stop( self ) : self.__isRunning_ = False

    class WorkerThread( threading.Thread ):
        def __init__( self, bgTask ):      
            threading.Thread.__init__( self )
            self.__bgTask_ = bgTask

        def run( self ):
            try :
                self.__bgTask_.taskFuncPointer()( self.__bgTask_.isRunning )
            except Exception as e: print repr(e)

Here's a Tk test which demos the use of these. Just append this to the bottom of the module with those classes in it if you want to see the demo in action:

def tkThreadingTest():

    from tkinter import Tk, Label, Button, StringVar
    from time import sleep

    class UnitTestGUI:

        def __init__( self, master ):
            self.master = master
            master.title( "Threading Test" )

            self.testButton = Button( 
                self.master, text="Blocking", command=self.myLongProcess )

            self.threadedButton = Button( 
                self.master, text="Threaded", command=self.onThreadedClicked )

            self.cancelButton = Button( 
                self.master, text="Stop", command=self.onStopClicked )

            self.statusLabelVar = StringVar()
            self.statusLabel = Label( master, textvariable=self.statusLabelVar )

            self.clickMeButton = Button( 
                self.master, text="Click Me", command=self.onClickMeClicked )

            self.clickCountLabelVar = StringVar()            
            self.clickCountLabel = Label( master,  textvariable=self.clickCountLabelVar )

            self.threadedButton = Button( 
                self.master, text="Timer", command=self.onTimerClicked )

            self.timerCountLabelVar = StringVar()            
            self.timerCountLabel = Label( master,  textvariable=self.timerCountLabelVar )



            self.bgTask = BackgroundTask( self.myLongProcess )

            self.timer = TkRepeatingTask( self.master, self.onTimer, 1 )

        def close( self ) :
            print "close"
            try: self.bgTask.stop()
            except: pass
            try: self.timer.stop()
            except: pass            

        def onThreadedClicked( self ):
            print "onThreadedClicked"
            try: self.bgTask.start()
            except: pass

        def onTimerClicked( self ) :
            print "onTimerClicked"

        def onStopClicked( self ) :
            print "onStopClicked"
            try: self.bgTask.stop()
            except: pass
            try: self.timer.stop()
            except: pass                        

        def onClickMeClicked( self ):
            print "onClickMeClicked"
            self.clickCountLabelVar.set( str(self.clickCounter_) )

        def onTimer( self ) :
            print "onTimer"
            self.timerCountLabelVar.set( str(self.timerCounter_) )

        def myLongProcess( self, isRunningFunc=None ) :
            print "starting myLongProcess"
            for i in range( 1, 10 ):
                    if not isRunningFunc() :
                        self.onMyLongProcessUpdate( "Stopped!" )
                except : pass   
                self.onMyLongProcessUpdate( i )
                sleep( 1.5 ) # simulate doing work
            self.onMyLongProcessUpdate( "Done!" )                

        def onMyLongProcessUpdate( self, status ) :
            print "Process Update: %s" % (status,)
            self.statusLabelVar.set( str(status) )

    root = Tk()    
    gui = UnitTestGUI( root )
    root.protocol( "WM_DELETE_WINDOW", gui.close )

if __name__ == "__main__": 

Two import points I'll stress about BackgroundTask:

1) The function you run in the background task needs to take a function pointer it will both invoke and respect, which allows the task to be cancelled mid way through - if possible.

2) You need to make sure the background task is stopped when you exit your application. That thread will still run even if your gui is closed if you don't address that!

phpmailer: Reply using only "Reply To" address

I have found the answer to this, and it is annoyingly/frustratingly simple! Basically the reply to addresses needed to be added before the from address as such:

$mail->addReplyTo('[email protected]', 'Reply to name');
$mail->SetFrom('[email protected]', 'Mailbox name');

Looking at the phpmailer code in more detail this is the offending line:

public function SetFrom($address, $name = '',$auto=1) {
   $address = trim($address);
   $name = trim(preg_replace('/[\r\n]+/', '', $name)); //Strip breaks and trim
   if (!self::ValidateAddress($address)) {
     $this->SetError($this->Lang('invalid_address').': '. $address);
     if ($this->exceptions) {
       throw new phpmailerException($this->Lang('invalid_address').': '.$address);
     echo $this->Lang('invalid_address').': '.$address;
     return false;
   $this->From = $address;
   $this->FromName = $name;
   if ($auto) {
      if (empty($this->ReplyTo)) {
         $this->AddAnAddress('ReplyTo', $address, $name);
      if (empty($this->Sender)) {
         $this->Sender = $address;
   return true;

Specifically this line:

if (empty($this->ReplyTo)) {
   $this->AddAnAddress('ReplyTo', $address, $name);

Thanks for your help everyone!

Check if a div does NOT exist with javascript

That works with :

 var element = document.getElementById('myElem');
 if (typeof (element) != undefined && typeof (element) != null && typeof (element) != 'undefined') {
     console.log('element exists');
     console.log('element NOT exists');

C# MessageBox dialog result

DialogResult result = MessageBox.Show("Do you want to save changes?", "Confirmation", MessageBoxButtons.YesNoCancel);
if(result == DialogResult.Yes)
else if (result == DialogResult.No)

Asyncio.gather vs asyncio.wait

A very important distinction, which is easy to miss, is the default bheavior of these two functions, when it comes to exceptions.

I'll use this example to simulate a coroutine that will raise exceptions, sometimes -

import asyncio
import random

async def a_flaky_tsk(i):
    await asyncio.sleep(i)  # bit of fuzz to simulate a real-world example

    if i % 2 == 0:
        print(i, "ok")
        print(i, "crashed!")
        raise ValueError

coros = [a_flaky_tsk(i) for i in range(10)]

await asyncio.gather(*coros) outputs -

0 ok
1 crashed!
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 20, in <module>
  File "/Users/dev/.pyenv/versions/3.8.2/lib/python3.8/asyncio/", line 43, in run
    return loop.run_until_complete(main)
  File "/Users/dev/.pyenv/versions/3.8.2/lib/python3.8/asyncio/", line 616, in run_until_complete
    return future.result()
  File "/Users/dev/PycharmProjects/trading/", line 17, in main
    await asyncio.gather(*coros)
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError

As you can see, the coros after index 1 never got to execute.

But await asyncio.wait(coros) continues to execute tasks, even if some of them fail -

0 ok
1 crashed!
2 ok
3 crashed!
4 ok
5 crashed!
6 ok
7 crashed!
8 ok
9 crashed!
Task exception was never retrieved
future: <Task finished name='Task-10' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError
Task exception was never retrieved
future: <Task finished name='Task-8' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError
Task exception was never retrieved
future: <Task finished name='Task-2' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError
Task exception was never retrieved
future: <Task finished name='Task-9' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError
Task exception was never retrieved
future: <Task finished name='Task-3' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/", line 12, in a_flaky_tsk
    raise ValueError

Ofcourse, this behavior can be changed for both by using -

asyncio.gather(..., return_exceptions=True)


asyncio.wait([...], return_when=asyncio.FIRST_EXCEPTION)

But it doesn't end here!

Notice: Task exception was never retrieved in the logs above.

asyncio.wait() won't re-raise exceptions from the child tasks until you await them individually. (The stacktrace in the logs are just messages, they cannot be caught!)

done, pending = await asyncio.wait(coros)
for tsk in done:
        await tsk
    except Exception as e:
        print("I caught:", repr(e))

Output -

0 ok
1 crashed!
2 ok
3 crashed!
4 ok
5 crashed!
6 ok
7 crashed!
8 ok
9 crashed!
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()

On the other hand, to catch exceptions with asyncio.gather(), you must -

results = await asyncio.gather(*coros, return_exceptions=True)
for result_or_exc in results:
    if isinstance(result_or_exc, Exception):
        print("I caught:", repr(result_or_exc))

(Same output as before)

Difference between hamiltonian path and euler path

Euler Path - An Euler path is a path in which each edge is traversed exactly once.

Hamiltonian Path - An Hamiltonian path is path in which each vertex is traversed exactly once.

If you have ever confusion remember E - Euler E - Edge.

How to represent a fix number of repeats in regular expression?

For Java:

Quantifiers documentation

X, exactly n times: X{n}
X, at least n times: X{n,}
X, at least n but not more than m times: X{n,m}

How to avoid using Select in Excel VBA

The main reason never to use Select or Activesheet is because most people will have at least another couple of workbooks open (sometimes dozens) when they run your macro, and if they click away from your sheet while your macro is running and click on some other book they have open, then the "Activesheet" changes, and the target workbook for an unqualified "Select" command changes as well.

At best, your macro will crash, at worst you might end up writing values or changing cells in the wrong workbook with no way to "Undo" them.

I have a simple golden rule that I follow: Add variables named "wb" and "ws" for a Workbook object and a Worksheet object and always use those to refer to my macro book. If I need to refer to more than one book, or more than one sheet, I add more variables.

For example,

Dim wb as Workbook
Dim ws as Worksheet
Set wb = ThisWorkBook
Set ws = wb.sheets("Output")

The "Set wb = ThisWorkbook" command is absolutely key. "ThisWorkbook" is a special value in Excel, and it means the workbook that your VBA code is currently running from. A very helpful shortcut to set your Workbook variable with.

After you've done that at the top of your Sub, using them could not be simpler, just use them wherever you would use "Selection":

So to change the value of cell "A1" in "Output" to "Hello", instead of:

Selection.Value = "Hello"

We can now do this:

ws.Range("A1").Value = "Hello"

Which is not only much more reliable and less likely to crash if the user is working with multiple spreadsheets; it's also much shorter, quicker and easier to write.

As an added bonus, if you always name your variables "wb" and "ws", you can copy and paste code from one book to another and it will usually work with minimal changes needed, if any.

How to use boolean datatype in C?

We can use enum type for this.We don't require a library. For example

           enum {false,true};

the value for false will be 0 and the value for true will be 1.

Cloning an array in Javascript/Typescript

Try this

const returnedTarget = Object.assign(target, source);

and pass empty array to target

in case complex objects this way works for me

$.extend(true, [], originalArray) in case of array

$.extend(true, {}, originalObject) in case of object

Bash loop ping successful

I liked paxdiablo's script, but wanted a version that ran indefinitely. This version runs ping until a connection is established and then prints a message saying so.

echo "Testing..."

PING_CMD="ping -t 3 -c 1 > /dev/null 2>&1"

eval $PING_CMD

if [[ $? -eq 0 ]]; then
    echo "Already connected."
    echo -n "Waiting for connection..."

    while true; do
        eval $PING_CMD

        if [[ $? -eq 0 ]]; then
            echo Connected.
            sleep 0.5
            echo -n .

I also have a Gist of this script which I'll update with fixes and improvements as needed.

Android change SDK version in Eclipse? Unable to resolve target android-x

If you're using eclipse you can open file in your workspace and change the project target to the new sdk (target=android-8 for 2.2). I accidentally selected the 1.5 sdk for my version and didn't catch it until much later, but updating that and restarting eclipse seemed to have done the trick.

Reverse ip, find domain names on ip address

They're just trawling lists of web sites, and recording the resulting IP addresses in a database.

All you're seeing is the reverse mapping of that list. It's not guaranteed to be a full list (indeed more often than not it won't be) because it's impossible to learn every possible web site address.

Spring 3 MVC resources and tag <mvc:resources />

<mvc:resources mapping="/resources/**"
               location="/, classpath:/WEB-INF/public-resources/"
               cache-period="10000" />

Put the resources under: src/main/webapp/images/logo.png and then access them via /resources/images/logo.png.

In the war they will be then located at images/logo.png. So the first location (/) form mvc:resources will pick them up.

The second location (classpath:/WEB-INF/public-resources/) in mvc:resources (looks like you used some roo based template) can be to expose resources (for example js-files) form jars, if they are located in the directory WEB-INF/public-resources in the jar.

MongoDB vs. Cassandra

I'm probably going to be an odd man out, but I think you need to stay with MySQL. You haven't described a real problem you need to solve, and MySQL/InnoDB is an excellent storage back-end even for blob/json data.

There is a common trick among Web engineers to try to use more NoSQL as soon as realization comes that not all features of an RDBMS are used. This alone is not a good reason, since most often NoSQL databases have rather poor data engines (what MySQL calls a storage engine).

Now, if you're not of that kind, then please specify what is missing in MySQL and you're looking for in a different database (like, auto-sharding, automatic failover, multi-master replication, a weaker data consistency guarantee in cluster paying off in higher write throughput, etc).

How do I include a JavaScript file in another JavaScript file?

Please note that we usually use static scripts. So we want to be taken from the cache as much as possible.

This saves network traffic and speeds up landing.


$.cachedScript( "ajax/test.js" ).done(function( script, textStatus ) {
  console.log( textStatus );

The cache: true option has been added to the Ajax method.

What is the <leader> in a .vimrc file?

Vim's <leader> key is a way of creating a namespace for commands you want to define. Vim already maps most keys and combinations of Ctrl + (some key), so <leader>(some key) is where you (or plugins) can add custom behavior.

For example, if you find yourself frequently deleting exactly 3 words and 7 characters, you might find it convenient to map a command via nmap <leader>d 3dw7x so that pressing the leader key followed by d will delete 3 words and 7 characters. Because it uses the leader key as a prefix, you can be (relatively) assured that you're not stomping on any pre-existing behavior.

The default key for <leader> is \, but you can use the command :let mapleader = "," to remap it to another key (, in this case).

Usevim's page on the leader key has more information.

What USB driver should we use for the Nexus 5?

This worked for me:

  1. Download the Nexus 5 Drivers from Google USB Driver
  2. Extract the ZIP contents and place all files in a single folder on your desktop.
  3. Connect your device to your computer.
  4. Launch the Device Manager on your PC.
  5. Now you should see the Nexus 5 listed in the hardware list.
  6. Right-click the ‘Nexus 5' line and then click on Update Driver Software.
  7. Next, click the ‘browse my computer’ option.
  8. In the new window, click on ‘Browse…’ button.
  9. Go to folder unzipped at step 2. Select the folder where you extract the USB drivers. Click Next.
    • Make sure to tick the subfolder box too.
  10. Now, the Windows installer will search for Nexus 5 drivers. Click Install when asked for permission.
  11. Wait for the process to complete and then check the Device Manager list to confirm that the installation was successful.

Source: Download and Install Google Nexus 5 USB Drivers (ADB / Fastboot)

node.js - how to write an array to file

We can simply write the array data to the filesystem but this will raise one error in which ',' will be appended to the end of the file. To handle this below code can be used:

var fs = require('fs');

var file = fs.createWriteStream('hello.txt');
file.on('error', function(err) { Console.log(err) });
data.forEach(value => file.write(`${value}\r\n`));


is used for the new Line.


won't help. Please refer this

How do I execute a command and get the output of the command within C++ using POSIX?

C++ stream implemention of waqas's answer:

#include <istream>
#include <streambuf>
#include <cstdio>
#include <cstring>
#include <memory>
#include <stdexcept>
#include <string>

class execbuf : public std::streambuf {
        std::string output;
        int_type underflow(int_type character) {
            if (gptr() < egptr()) return traits_type::to_int_type(*gptr());
            return traits_type::eof();
        execbuf(const char* command) {
            std::array<char, 128> buffer;
            std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(command, "r"), pclose);
            if (!pipe) {
                throw std::runtime_error("popen() failed!");
            while (fgets(, buffer.size(), pipe.get()) != nullptr) {
                this->output +=;
            setg((char*)this->, (char*)this->, (char*)(this-> + this->output.size()));

class exec : public std::istream {
        execbuf buffer;
        exec(char* command) : std::istream(nullptr), buffer(command, fd) {

This code catches all output through stdout . If you want to catch only stderr then pass your command like this:

sh -c '<your-command>' 2>&1 > /dev/null

If you want to catch both stdout and stderr then the command should be like this:

sh -c '<your-command>' 2>&1

Quickly reading very large tables as dataframes

Often times I think it is just good practice to keep larger databases inside a database (e.g. Postgres). I don't use anything too much larger than (nrow * ncol) ncell = 10M, which is pretty small; but I often find I want R to create and hold memory intensive graphs only while I query from multiple databases. In the future of 32 GB laptops, some of these types of memory problems will disappear. But the allure of using a database to hold the data and then using R's memory for the resulting query results and graphs still may be useful. Some advantages are:

(1) The data stays loaded in your database. You simply reconnect in pgadmin to the databases you want when you turn your laptop back on.

(2) It is true R can do many more nifty statistical and graphing operations than SQL. But I think SQL is better designed to query large amounts of data than R.

# Looking at Voter/Registrant Age by Decade


con <- dbConnect(PostgreSQL(), user= "postgres", password="password",
                 port="2345", host="localhost", dbname="WC2014_08_01_2014")

Decade_BD_1980_42 <- dbGetQuery(con,"Select PrecinctID,Count(PrecinctID),extract(DECADE from Birthdate) from voterdb where extract(DECADE from Birthdate)::numeric > 198 and PrecinctID in (Select * from LD42) Group By PrecinctID,date_part Order by Count DESC;")

Decade_RD_1980_42 <- dbGetQuery(con,"Select PrecinctID,Count(PrecinctID),extract(DECADE from RegistrationDate) from voterdb where extract(DECADE from RegistrationDate)::numeric > 198 and PrecinctID in (Select * from LD42) Group By PrecinctID,date_part Order by Count DESC;")

with(Decade_BD_1980_42,(barchart(~count | as.factor(precinctid))));
mtext("42LD Birthdays later than 1980 by Precinct",side=1,line=0)

with(Decade_RD_1980_42,(barchart(~count | as.factor(precinctid))));
mtext("42LD Registration Dates later than 1980 by Precinct",side=1,line=0)

$.focus() not working

I also had this problem. The solution that worked in my case was using the tabindex property on the HTML element.

I was using ng-repeat for some li elements inside a list and I was not able to bring focus to the first li using .focus(), so I simply added the tabindex attribute to each li during the loop.

so now <li ng-repeat="user in users track by $index" tabindex="{{$index+1}}"></li>

That +1 was index starts from 0. Also make sure that the element is present in DOM before calling the .focus() function

I hope this helps.

Delete everything in a MongoDB database

Also, from the command line:

mongo DATABASE_NAME --eval "db.dropDatabase();"

How to install python developer package?

yum install python-devel will work.

If yum doesn't work then use

apt-get install python-dev

How to find Google's IP address?

If all you are trying to do is find the IP address that corresponds to a domain name, like, this is very easy on every machine connected to the Internet.

Simply run the ping command from any command prompt. Typing something like


will give you (among other things) that information.

Event binding on dynamically created elements?

This is a pure JavaScript solution without any libraries or plugins:

document.addEventListener('click', function (e) {
    if (hasClass(, 'bu')) {
        // .bu clicked
        // Do your thing
    } else if (hasClass(, 'test')) {
        // .test clicked
        // Do your other thing
}, false);

where hasClass is

function hasClass(elem, className) {
    return elem.className.split(' ').indexOf(className) > -1;

Live demo

Credit goes to Dave and Sime Vidas

Using more modern JS, hasClass can be implemented as:

function hasClass(elem, className) {
    return elem.classList.contains(className);

How can jQuery deferred be used?

You can also integrate it with any 3rd-party libraries which makes use of JQuery.

One such library is Backbone, which is actually going to support Deferred in their next version.

CSS strikethrough different color from text?

If it helps someone you can just use css property

text-decoration-color: red;

How to export datagridview to excel using

A simple way of generating a printable report from a Datagridview is to place the datagridview on a Panel object. It is possible to draw a bitmap of the panel.

Here's how I do it.

'create the bitmap with the dimentions of the Panel Dim bmp As New Bitmap(Panel1.Width, Panel1.Height)

'draw the Panel to the bitmap "bmp" Panel1.DrawToBitmap(bmp, Panel1.ClientRectangle)

I create a multi page tiff by "breaking my datagridview items into pages. this is how i detect the start of a new page:

'i add the rows to my datagrid one at a time and then check if the scrollbar is active. 'if the scrollbar is active i save the row to a variable and then i remove it from the 'datagridview and roll back my counter integer by one(thus the next run will include this 'row.

Private Function VScrollBarVisible() As Boolean
    Dim ctrl As New Control
    For Each ctrl In DataGridView_Results.Controls
        If ctrl.GetType() Is GetType(VScrollBar) Then
            If ctrl.Visible = True Then
                Return True
                Return False
            End If
        End If
    Return Nothing
End Function

I hope this helps

What does upstream mean in nginx?

It's used for proxying requests to other servers.

An example from is:

http {
  upstream myproject {
    server weight=3;

  server {
    listen 80;
    location / {
      proxy_pass http://myproject;

This means all requests for / go to the any of the servers listed under upstream XXX, with a preference for port 8000.

How to split the filename from a full path in batch?

I don't know that much about batch files but couldn't you have a pre-made batch file copied from the home directory to the path you have that would return a list of the names of the files then use that name?

Here is a link I think might be helpful in making the pre-made batch file.

Reload nginx configuration

Maybe you're not doing it as root?

Try sudo nginx -s reload, if it still doesn't work, you might want to try sudo pkill -HUP nginx.

Unable to establish SSL connection upon wget on Ubuntu 14.04 LTS

Although this is almost certainly not the OPs issue, you can also get Unable to establish SSL connection from wget if you're behind a proxy and don't have HTTP_PROXY and HTTPS_PROXY environment variables set correctly. Make sure to set HTTP_PROXY and HTTPS_PROXY to point to your proxy.

This is a common situation if you work for a large corporation.

How to delete columns in pyspark dataframe

Reading the Spark documentation I found an easier solution.

Since version 1.4 of spark there is a function drop(col) which can be used in pyspark on a dataframe.

You can use it in two ways

  1. df.drop('age').collect()
  2. df.drop(df.age).collect()

Pyspark Documentation - Drop

VBA: How to display an error message just like the standard error message which has a "Debug" button?

For Me I just wanted to see the error in my VBA application so in the function I created the below code..

Function Database_FileRpt
On Error GoTo CleanFail
' Create_DailyReport_Action and code



MsgBox "********************" _

& vbCrLf & "Err.Number: " & Err.Number _

& vbCrLf & "Err.Description: " & Err.Description _

& vbCrLf & "Err.Source: " & Err.Source _

& vbCrLf & "********************" _

& vbCrLf & "...Exiting VBA Function: Database_FileRpt" _

& vbCrLf & "...Excel VBA Program Reset." _

, , "VBA Error Exception Raised!"


 ' Note that the next line will reset the error object to 0, the variables 
above are used to remember the values
' so that the same error can be re-raised


' *************************************

Resume CleanExit


'cleanup code , if any, goes here. runs regardless of error state.

Exit Function  ' SUB  or Function    

End Function  ' end of Database_FileRpt

' ------------------

Is JavaScript guaranteed to be single-threaded?

JavaScript/ECMAScript is designed to live within a host environment. That is, JavaScript doesn't actually do anything unless the host environment decides to parse and execute a given script, and provide environment objects that let JavaScript actually be useful (such as the DOM in browsers).

I think a given function or script block will execute line-by-line and that is guaranteed for JavaScript. However, perhaps a host environment could execute multiple scripts at the same time. Or, a host environment could always provide an object that provides multi-threading. setTimeout and setInterval are examples, or at least pseudo-examples, of a host environment providing a way to do some concurrency (even if it's not exactly concurrency).

What does this thread join code mean?

Hope it helps!

package join;

public class ThreadJoinApp {

    Thread th = new Thread("Thread 1") {
        public void run() {
            System.out.println("Current thread execution - " + Thread.currentThread().getName());
            for (int i = 0; i < 10; i++) {
                System.out.println("Current thread execution - " + Thread.currentThread().getName() + " at index - " + i);

    Thread th2 = new Thread("Thread 2") {
        public void run() {
            System.out.println("Current thread execution - " + Thread.currentThread().getName());

            //Thread 2 waits until the thread 1 successfully completes.
            try {
            } catch( InterruptedException ex) {
                System.out.println("Exception has been caught");

            for (int i = 0; i < 10; i++) {
                System.out.println("Current thread execution - " + Thread.currentThread().getName() + " at index - " + i);

    public static void main(String[] args) {
        ThreadJoinApp threadJoinApp = new ThreadJoinApp();;

    //Happy coding -- Parthasarathy S

How do I run all Python unit tests in a directory?

I tried various approaches but all seem flawed or I have to makeup some code, that's annoying. But there's a convinient way under linux, that is simply to find every test through certain pattern and then invoke them one by one.

find . -name 'Test*py' -exec python '{}' \;

and most importantly, it definitely works.

Can you recommend a free light-weight MySQL GUI for Linux?

I really like the MySQL collection of of GUI Tools. They aren't too large or resource hungry.

There are quite a few options here as well. Of the applications presented on that page, I like SQL Buddy - it does require a web server, however.

"error: assignment to expression with array type error" when I assign a struct field (C)

You are facing issue in"Paolo";

because, in the LHS, you're using an array type, which is not assignable.

To elaborate, from C11, chapter §6.5.16

assignment operator shall have a modifiable lvalue as its left operand.

and, regarding the modifiable lvalue, from chapter §

A modifiable lvalue is an lvalue that does not have array type, [...]

You need to use strcpy() to copy into the array.

That said, data s1 = {"Paolo", "Rossi", 19}; works fine, because this is not a direct assignment involving assignment operator. There we're using a brace-enclosed initializer list to provide the initial values of the object. That follows the law of initialization, as mentioned in chapter §6.7.9

Each brace-enclosed initializer list has an associated current object. When no designations are present, subobjects of the current object are initialized in order according to the type of the current object: array elements in increasing subscript order, structure members in declaration order, and the first named member of a union.[....]

How do I scroll the UIScrollView when the keyboard appears?

You can scroll by using the property contentOffset in UIScrollView, e.g.,

CGPoint offset = scrollview.contentOffset;
offset.y -= KEYBOARD_HEIGHT + 5;
scrollview.contentOffset = offset;

There's also a method to do animated scrolling.

As for the reason why your second edit is not scrolling correctly, it could be because you seem to assume that a new keyboard will appear every time editing starts. You could try checking if you've already adjusted for the "keyboard" visible position (and likewise check for keyboard visibility at the moment before reverting it).

A better solution might be to listen for the keyboard notification, e.g.:

[[NSNotificationCenter defaultCenter] addObserver:self
[[NSNotificationCenter defaultCenter] addObserver:self

input type="submit" Vs button tag are they interchangeable?

<input type='submit' /> doesn't support HTML inside of it, since it's a single self-closing tag. <button>, on the other hand, supports HTML, images, etc. inside because it's a tag pair: <button><img src='myimage.gif' /></button>. <button> is also more flexible when it comes to CSS styling.

The disadvantage of <button> is that it's not fully supported by older browsers. IE6/7, for example, don't display it correctly.

Unless you have some specific reason, it's probably best to stick to <input type='submit' />.

Check if number is prime number

  • A prime number is odd except 2
  • 1 or 0 is neither prime nor composite


  1. Add a counter to check how many times the input number is divisible by i (and has 0 (zero) remainder)
  2. If counter is = 2, then input is prime, else not prime
  3. If counter is > 2 "break" to avoid unnecessary processes (if you want to count the factors of your input number remove " || counter > 2 " on the first if statement)
  4. Add this line of code at the 2nd if statement inside the for loop if you want to see how many numbers with remainder 0 (or factors are present) :
Console.WriteLine( $" {inputNumber} / {i} = { inputNumber / i} (remainder: {inputNumber % i})" ); 
  1. Add the line of code in number 4 (at the end of the for loop) to see all the all the numbers divided by your input number (in case you want to see the remainder output and the quotient)
Console.Write( "Enter a Positive Number: " );
int inputNumber = Convert.ToInt32( Console.ReadLine() );
int counter = 0;

    for ( int i = 1; i <= inputNumber; i++ ) {
        if ( inputNumber == 0 || inputNumber == 1 || counter > 2 ) { break; }
        if ( inputNumber % i == 0 ) { counter++; }

    if ( counter == 2 ) {
        Console.WriteLine( $"{inputNumber} is a prime number." );
    } else if ( inputNumber == 1 || inputNumber == 0 ) {
        Console.WriteLine( $"{inputNumber} is neither prime nor composite." );
    } else {
        Console.WriteLine( $"{inputNumber} is not a prime number. (It is a composite number)" );

My reference:

What is the difference between HTML tags <div> and <span>?

<div> is a block-level element and <span> is an inline element.

If you wanted to do something with some inline text, <span> is the way to go since it will not introduce line breaks that a <div> would.

As noted by others, there are some semantics implied with each of these, most significantly the fact that a <div> implies a logical division in the document, akin to maybe a section of a document or something, a la:

<div id="Chapter1">
   <p>Lorem ipsum dolor sit amet, <span id="SomeSpecialText1">consectetuer adipiscing</span> elit. Duis congue vehicula purus.</p>
   <p>Nam <span id="SomeSpecialText2">eget magna nec</span> sapien fringilla euismod. Donec hendrerit.</p> 

Cannot resolve symbol 'AppCompatActivity'

You Have to just Do some change in your Gradle App File by adding some dependency

compile ""

while XX:YY:ZZ is the version code that you are using in your gradle file, otherwise if you set this version lower or higher than that you are using , then your app will face some problems like it will crash sometimes

Performance of Arrays vs. Lists

Very easy to measure...

In a small number of tight-loop processing code where I know the length is fixed I use arrays for that extra tiny bit of micro-optimisation; arrays can be marginally faster if you use the indexer / for form - but IIRC believe it depends on the type of data in the array. But unless you need to micro-optimise, keep it simple and use List<T> etc.

Of course, this only applies if you are reading all of the data; a dictionary would be quicker for key-based lookups.

Here's my results using "int" (the second number is a checksum to verify they all did the same work):

(edited to fix bug)

List/for: 1971ms (589725196)
Array/for: 1864ms (589725196)
List/foreach: 3054ms (589725196)
Array/foreach: 1860ms (589725196)

based on the test rig:

using System;
using System.Collections.Generic;
using System.Diagnostics;
static class Program
    static void Main()
        List<int> list = new List<int>(6000000);
        Random rand = new Random(12345);
        for (int i = 0; i < 6000000; i++)
        int[] arr = list.ToArray();

        int chk = 0;
        Stopwatch watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 100; rpt++)
            int len = list.Count;
            for (int i = 0; i < len; i++)
                chk += list[i];
        Console.WriteLine("List/for: {0}ms ({1})", watch.ElapsedMilliseconds, chk);

        chk = 0;
        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 100; rpt++)
            for (int i = 0; i < arr.Length; i++)
                chk += arr[i];
        Console.WriteLine("Array/for: {0}ms ({1})", watch.ElapsedMilliseconds, chk);

        chk = 0;
        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 100; rpt++)
            foreach (int i in list)
                chk += i;
        Console.WriteLine("List/foreach: {0}ms ({1})", watch.ElapsedMilliseconds, chk);

        chk = 0;
        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 100; rpt++)
            foreach (int i in arr)
                chk += i;
        Console.WriteLine("Array/foreach: {0}ms ({1})", watch.ElapsedMilliseconds, chk);