Programs & Examples On #Twisted

Twisted is an event-driven networking engine, written in Python and implementing many different protocols.

TypeError: Object of type 'bytes' is not JSON serializable

I guess the answer you need is referenced here Python sets are not json serializable

Not all datatypes can be json serialized . I guess pickle module will serve your purpose.

"SSL certificate verify failed" using pip to install packages

One note on the above answers: it is no longer sufficient to add just to the trusted-hosts in the case where you are behind an HTTPS-intercepting proxy (we have zScaler).

I currently have the following in my pip.ini:

trusted-host =

Running pip -v install pkg will give you some hints as to which hosts might need to be added.

"OSError: [Errno 1] Operation not permitted" when installing Scrapy in OSX 10.11 (El Capitan) (System Integrity Protection)

  1. -- close SIP(system Integrity Protection) -- then reboot, use command +R to enter debug mode, then select terminal: csrutil disable reboot


sudo C_INCLUDE_PATH=/Applications/ :/Applications/ :/Applications/ pip install scrapy --ignore-installed six

3. -- then remove old six, install it again sudo rm -rf /Library/Python/2.7/site-packages/six* sudo rm -rf /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/six* sudo pip install six

4. -- then set it back csrutil enable reboot

-- crappy works now

Making an asynchronous task in Flask

I would use Celery to handle the asynchronous task for you. You'll need to install a broker to serve as your task queue (RabbitMQ and Redis are recommended).

from flask import Flask
from celery import Celery

broker_url = 'amqp://guest@localhost'          # Broker URL for RabbitMQ task queue

app = Flask(__name__)    
celery = Celery(, broker=broker_url)
celery.config_from_object('celeryconfig')      # Your celery configurations in a

def some_long_task(self, x, y):
    # Do some long task

@app.route('/render/<id>', methods=['POST'])
def render_script(id=None):
    data = json.loads(
    text_list = data.get('text_list')
    final_file = audio_class.render_audio(data=text_list)
    some_long_task.delay(x, y)                 # Call your async task and pass whatever necessary variables
    return Response(

Run your Flask app, and start another process to run your celery worker.

$ celery worker -A app.celery --loglevel=debug

I would also refer to Miguel Gringberg's write up for a more in depth guide to using Celery with Flask.

Pip Install not installing into correct directory?

You could just change the shebang line. I do this all the time on new systems.

If you want pip to install to a current version of Python installed just update the shebang line to the correct version of pythons path.

For example, to change pip (not pip3) to install to Python 3:




Any module you install using pip should install to Python not Python.

Or you could just change the path.

Python Socket Multiple Clients

This program will open 26 sockets where you would be able to connect a lot of TCP clients to it.

from thread import *
import socket
import sys

def clientthread(conn):
    while True:
        data = conn.recv(8192)
        print buffer

def main():
        host = ''
        port = 6666
        tot_socket = 26
        list_sock = []
        for i in range(tot_socket):
            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s.bind((host, port+i))
            print "[*] Server listening on %s %d" %(host, (port+i))

        while 1:
            for j in range(len(list_sock)):
                conn, addr = list_sock[j].accept()
                print '[*] Connected with ' + addr[0] + ':' + str(addr[1])
                start_new_thread(clientthread ,(conn,))

    except KeyboardInterrupt as msg:

if __name__ == "__main__":

How do I hide the bullets on my list for the sidebar?

You have a selector ul on line 252 which is setting list-style: square outside none (a square bullet). You'll have to change it to list-style: none or just remove the line.

If you only want to remove the bullets from that specific instance, you can use the specific selector for that list and its items as follows:

ul#groups-list.items-list { list-style: none }

How can I break from a try/catch block without throwing an exception in Java

In this sample in catch block i change the value of counter and it will break while block:

class TestBreak {
    public static void main(String[] a) {
        int counter = 0;

        while(counter<5) {
            try {
                int x = counter/0;
            catch(Exception e) {
                counter = 1000;    

Difference between socket and websocket?

To answer your questions.

  1. Even though they achieve (in general) similar things, yes, they are really different. WebSockets typically run from browsers connecting to Application Server over a protocol similar to HTTP that runs over TCP/IP. So they are primarily for Web Applications that require a permanent connection to its server. On the other hand, plain sockets are more powerful and generic. They run over TCP/IP but they are not restricted to browsers or HTTP protocol. They could be used to implement any kind of communication.
  2. No. There is no reason.

How can I create a simple message box in Python?

In Windows, you can use ctypes with user32 library:

from ctypes import c_int, WINFUNCTYPE, windll
from ctypes.wintypes import HWND, LPCSTR, UINT
paramflags = (1, "hwnd", 0), (1, "text", "Hi"), (1, "caption", None), (1, "flags", 0)
MessageBox = prototype(("MessageBoxA", windll.user32), paramflags)

MessageBox(text="Spam, spam, spam")
MessageBox(flags=2, text="foo bar")

What is the current choice for doing RPC in Python?

maybe ZSI which implements SOAP. I used the stub generator and It worked properly. The only problem I encountered is about doing SOAP throught HTTPS.

Validate SSL certificates with Python

I was having the same problem but wanted to minimize 3rd party dependencies (because this one-off script was to be executed by many users). My solution was to wrap a curl call and make sure that the exit code was 0. Worked like a charm.

How to scp in Python?

You might be interested in trying Pexpect (source code). This would allow you to deal with interactive prompts for your password.

Here's a snip of example usage (for ftp) from the main website:

# This connects to the openbsd ftp site and
# downloads the recursive directory listing.
import pexpect
child = pexpect.spawn ('ftp')
child.expect ('Name .*: ')
child.sendline ('anonymous')
child.expect ('Password:')
child.sendline ('[email protected]')
child.expect ('ftp> ')
child.sendline ('cd pub')
child.expect('ftp> ')
child.sendline ('get ls-lR.gz')
child.expect('ftp> ')
child.sendline ('bye')

why windows 7 task scheduler task fails with error 2147942667

This can happen for more than one reason. In my case this happened due to a permissions issue. The user that the task was running as didn't have permission to write to the logs directory so it failed with this error.

Group dataframe and get sum AND count?

If you have lots of columns and only one is different you could do:

In[1]: grouper = df.groupby('Company Name')
In[2]: res = grouper.count()
In[3]: res['Amount'] = grouper.Amount.sum()
In[4]: res
                      Organisation Name   Amount
Company Name                                   
Vifor Pharma UK Ltd                  5  4207.93

Note you can then rename the Organisation Name column as you wish.

Convert a string into an int

NSString *string = /* Assume this exists. */;
int value = [string intValue];

How to print pthread_t

I know, this thread is very old. Having read all above posts, I would like to add one more idea to handle this in a neat way: If you get into the mapping business anyway (mapping pthread_to to an int), you could as well go one step further in readability. Make your pthread_create_wrapper such that it takes a string, too...the name of the thread. I learned to appreciate this "SetThreadName()" feature on windows and windows CE. Advantages: Your ids are not just numbers but you also see, which of your threads has which purpose.

Postman addon's like in firefox

The feature that I'm missing a lot from postman in Firefox extensions is WebView
(preview when API returns HTML).

Now I'm settled with Fiddler (Inspectors > WebView) validation to make sure textbox has integer values

simpally add this code:

<asp:FilteredTextBoxExtender ID="txtAltitudeMin_FilteredTextBoxExtender" runat="server" Enabled="True" TargetControlID="txtAltitudeMin" FilterType="Numbers"></asp:FilteredTextBoxExtender>

Javascript add leading zeroes to date

As @John Henckel suggests, starting using the toISOString() method makes things easier

const dateString = new Date().toISOString().split('-');_x000D_
const year = dateString[0];_x000D_
const month = dateString[1];_x000D_
const day = dateString[2].split('T')[0];_x000D_

Testing socket connection in Python

12 years later for anyone having similar problems.

    s.connect((address, '80'))
    alert('failed' + address, 'down')

doesn't work because the port '80' is a string. Your port needs to be int.

    s.connect((address, 80))

This should work. Not sure why even the best answer didnt see this.

How to obtain the number of CPUs/cores in Linux from the command line?

I also thought cat /proc/cpuinfo would give me the correct answer, however I recently saw that my ARM quad core Cortex A53 system only showed a single core. It seems that /proc/cpuinfo only shows the active cores, whereas:

cat /sys/devices/system/cpu/present

is a better measure of what's there. You can also

cat /sys/devices/system/cpu/online

to see which cores are online, and

cat /sys/devices/system/cpu/offline

to see which cores are offline. The online, offline, and present sysfs entries return the index of the CPUS, so a return value of 0 just means core 0, whereas a return value of 1-3 means cores 1,2, and 3.


ImportError: numpy.core.multiarray failed to import

I was getting the same error and was able to solve it by updating my numpy installation to 1.8.0:

pip install -U numpy

Refreshing all the pivot tables in my excel workbook with a macro

There is a refresh all option in the Pivot Table tool bar. That is enough. Dont have to do anything else.

Press ctrl+alt+F5

How to run Spyder in virtual environment?

The above answers are correct but I calling spyder within my virtualenv would still use my PATH to look up the version of spyder in my default anaconda env. I found this answer which gave the following workaround:

source activate my_env            # activate your target env with spyder installed
conda info -e                     # look up the directory of your conda env
find /path/to/my/env -name spyder # search for the spyder executable in your env
/path/to/my/env/then/to/spyder    # run that executable directly

I chose this over modifying PATH or adding a link to the executable at a higher priority in PATH since I felt this was less likely to break other programs. However, I did add an alias to the executable in ~/.bash_aliases.

How to sort by two fields in Java?

Create as many comparators as necessary. After, call the method "thenComparing" for each order category. It's a way of doing by Streams. See:

//Sort by first and last name
System.out.println("\n2.Sort list of person objects by firstName then "
                                        + "by lastName then by age");
Comparator<Person> sortByFirstName 
                            = (p, o) -> p.firstName.compareToIgnoreCase(o.firstName);
Comparator<Person> sortByLastName 
                            = (p, o) -> p.lastName.compareToIgnoreCase(o.lastName);
Comparator<Person> sortByAge 
                            = (p, o) ->,o.age);

//Sort by first Name then Sort by last name then sort by age

Look: Sort user defined object on multiple fields – Comparator (lambda stream)

How to change the server port from 3000?

You can change it inside bs-config.json file as mentioned in the docs

For example,

  "port": 8000,
  "files": ["./src/**/*.{html,htm,css,js}"],
  "server": { "baseDir": "./src" }

Take screenshots in the iOS simulator

on iOS Simulator,

Press Command + control + c or from menu : Edit>Copy Screen

open "Preview" app, Press Command + n or from menu : File> New from clipboard , then you can save command+s

For Retina, activate iOS Simulator then on menu:HardWare>Device>iPhone (Retina) and follow above process

Command + S

is the way to save on Desktop, (on new iPhone simulators, this was introduced in later simulator)

What is the meaning of single and double underscore before an object name?

Your question is good, it is not only about methods. Functions and objects in modules are commonly prefixed with one underscore as well, and can be prefixed by two.

But __double_underscore names are not name-mangled in modules, for example. What happens is that names beginning with one (or more) underscores are not imported if you import all from a module (from module import *), nor are the names shown in help(module).

XPath test if node value is number

There's an amazing type test operator in XPath 2.0 you can use:

<xsl:if test="$number castable as xs:double">
    <!-- implementation -->

How to get thread id from a thread pool?

The accepted answer answers the question about getting a thread id, but it doesn't let you do "Thread X of Y" messages. Thread ids are unique across threads but don't necessarily start from 0 or 1.

Here is an example matching the question:

import java.util.concurrent.*;
class ThreadIdTest {

  public static void main(String[] args) {

    final int numThreads = 5;
    ExecutorService exec = Executors.newFixedThreadPool(numThreads);

    for (int i=0; i<10; i++) {
      exec.execute(new Runnable() {
        public void run() {
          long threadId = Thread.currentThread().getId();
          System.out.println("I am thread " + threadId + " of " + numThreads);


and the output:

burhan@orion:/dev/shm$ javac && java ThreadIdTest
I am thread 8 of 5
I am thread 9 of 5
I am thread 10 of 5
I am thread 8 of 5
I am thread 9 of 5
I am thread 11 of 5
I am thread 8 of 5
I am thread 9 of 5
I am thread 10 of 5
I am thread 12 of 5

A slight tweak using modulo arithmetic will allow you to do "thread X of Y" correctly:

// modulo gives zero-based results hence the +1
long threadId = Thread.currentThread().getId()%numThreads +1;

New results:

burhan@orion:/dev/shm$ javac && java ThreadIdTest  
I am thread 2 of 5 
I am thread 3 of 5 
I am thread 3 of 5 
I am thread 3 of 5 
I am thread 5 of 5 
I am thread 1 of 5 
I am thread 4 of 5 
I am thread 1 of 5 
I am thread 2 of 5 
I am thread 3 of 5 

Converting a string to a date in DB2

Okay, seems like a bit of a hack. I have got it to work using a substring, so that only the part of the string with the date (not the time) gets passed into the DATE function...


I will still accept any answers that are better than this one!

is of a type that is invalid for use as a key column in an index

There is a limitation in SQL Server (up till 2008 R2) that varchar(MAX) and nvarchar(MAX) (and several other types like text, ntext ) cannot be used in indices. You have 2 options:
1. Set a limited size on the key field ex. nvarchar(100)
2. Create a check constraint that compares the value with all the keys in the table. The condition is:


and [dbo].[CheckKey] is a scalar function defined as:

CREATE FUNCTION [dbo].[CheckKey]
    @key nvarchar(max)
    declare @res bit
    if exists(select * from key_value where [key] = @key)
        set @res = 0
        set @res = 1

    return @res

But note that a native index is more performant than a check constraint so unless you really can't specify a length, don't use the check constraint.

How to convert a file into a dictionary?

This will leave the key as a string:

with open('infile.txt') as f:
  d = dict(x.rstrip().split(None, 1) for x in f)

Angular2, what is the correct way to disable an anchor element?

consider the following solution

.disable-anchor-tag { 
  pointer-events: none; 

how to add picasso library in android studio

Add this to your dependencies in build.gradle:

enter image description here

dependencies {
 implementation 'com.squareup.picasso:picasso:2.71828'

The latest version can be found here

Make sure you are connected to the Internet. When you sync Gradle, all related files will be added to your project

Take a look at your libraries folder, the library you just added should be in there.

enter image description here

Interpreting "condition has length > 1" warning from `if` function

if statement is not vectorized. For vectorized if statements you should use ifelse. In your case it is sufficient to write

w <- function(a){
if (any(a>0)){
  else 1

or a short vectorised version

ifelse(a > 0, a/sum(a), 1)

It depends on which do you want to use, because first function gives output vector of length 1 (in else part) and ifelse gives output vector of length equal to length of a.

Inline <style> tags vs. inline css properties

Style rules can be attached using:

  • External Files
  • In-page Style Tags
  • Inline Style Attribute

Generally, I prefer to use linked style sheets because they:

  • can be cached by browsers for performance; and
  • are a lot easier to maintain for a development perspective.

However, your question is asking specifically about the style tag versus inline styles. Prefer to use the style tag, in this case, because it:

  • provides a clear separation of markup from styling;
  • produces cleaner HTML markup; and
  • is more efficient with selectors to apply rules to multiple elements on a page improving management as well as making your page size smaller.

Inline elements only affect their respective element.

An important difference between the style tag and the inline attribute is specificity. Specificity determines when one style overrides another. Generally, inline styles have a higher specificity.

Read CSS: Specificity Wars for an entertaining look at this subject.

I hope that helps!

Swift error : signal SIGABRT how to solve it

You get a SIGABRT error whenever you have a disconnected outlet. Click on your view controller in the storyboard and go to connections in the side panel (the arrow symbol). See if you have an extra outlet there, a duplicate, or an extra one that's not connected. If it's not that then maybe you haven't connected your outlets to your code correctly.

Just remember that SIGABRT happens when you are trying to call an outlet (button, view, textfield, etc) that isn't there.

Regular expression to stop at first match

import regex
text = 'ask her to call Mary back when she comes back'                           
p = r'(?i)(?s)call(.*?)back'
for match in regex.finditer(p, str(text)):
    print (

Output: Mary

TERM environment variable not set

You've answered the question with this statement:

Cron calls this .sh every 2 minutes

Cron does not run in a terminal, so why would you expect one to be set?

The most common reason for getting this error message is because the script attempts to source the user's .profile which does not check that it's running in a terminal before doing something tty related. Workarounds include using a shebang line like:

#!/bin/bash -p

Which causes the sourcing of system-level profile scripts which (one hopes) does not attempt to do anything too silly and will have guards around code that depends on being run from a terminal.

If this is the entirety of the script, then the TERM error is coming from something other than the plain content of the script.

PHP/regex: How to get the string value of HTML tag?

Since attribute values may contain a plain > character, try this regular expression:

$pattern = '/<'.preg_quote($tagname, '/').'(?:[^"'>]*|"[^"]*"|\'[^\']*\')*>(.*?)<\/'.preg_quote($tagname, '/').'>/s';

But regular expressions are not suitable for parsing non-regular languages like HTML. You should better use a parser like SimpleXML or DOMDocument.

Generate UML Class Diagram from Java Project

I´d say MoDisco is by far the most powerful one (though probably not the easiest one to work with).

MoDisco is a generic reverse engineering framework (so that you can customize your reverse engineering project, with MoDisco you can even reverse engineer the behaviour of the java methods, not only the structure and signatures) but also includes some predefined features like the generation of class diagrams out of Java code that you need.

Sum values from an array of key-value pairs in JavaScript

Or in ES6

values.reduce((a, b) => a + b),


[1,2,3].reduce((a, b)=>a+b) // return 6

How to SUM parts of a column which have same text value in different column in the same row

If your data has the names grouped as shown then you can use this formula in D2 copied down to get a total against the last entry for each name


See screenshot

enter image description here

Android selector & text color

In order to make it work on selection in a list view use the following code:

<selector xmlns:android="">
    <item android:state_pressed="true" android:color="#fff"/>
    <item android:state_activated="true" android:color="#fff"/>
    <item android:color="#000" />

Apparently the key is state_activated="true" state.

When should you NOT use a Rules Engine?

That's certainly a good start. The other thing with rules engines is that some things are well-understood, deterministic, and straight-forward. Payroll withholding is (or use to be) like that. You could express it as rules that would be resolved by a rules engine, but you could express the same rules as a fairly simple table of values.

So, workflow engines are good when you're expressing a longer-term process that will have persistent data. Rules engines can do a similar thing, but you have to do a lot of added complexity.

Rules engines are good when you have complicated knowledge bases and need search. Rules engines can resolve complicated issues, and can be adapted quickly to changing situations, but impose a lot of complexity on the base implementation.

Many decision algorithms are simple enough to express as a simple table-driven program without the complexity implied by a real rules engine. with headers

Use POST instead

Although it is easy to construct a GET query using, it's a bad idea (see below). One workaround is to create a form that submits a POST request. Like so:

<form id="helper" action="###/your_page###" style="display:none">
<inputtype="hidden" name="headerData" value="(default)">

<input type="button" onclick="loadNnextPage()" value="Click me!">

function loadNnextPage() {
  document.getElementById("helper").headerData.value = "New";

Of course you will need something on the server side to handle this; as others have suggested you could create a "proxy" script that sends headers on your behalf and returns the results.

Problems with GET

  • Query strings get stored in browser history,
  • can be shoulder-surfed
  • copy-pasted,
  • and often you don't want it to be easy to "refresh" the same transaction.

Official reasons for "Software caused connection abort: socket write error"

The is thrown when there is an error creating or accessing a socket (such as TCP). This usually can be caused when the server has terminated the connection (without properly closing it), so before getting the full response. In most cases this can be caused either by the timeout issue (e.g. the response takes too much time or server is overloaded with the requests), or the client sent the SYN, but it didn't receive ACK (acknowledgment of the connection termination). For timeout issues, you can consider increasing the timeout value.

The Socket Exception usually comes with the specified detail message about the issue.

Example of detailed messages:

  • Software caused connection abort: recv failed.

    The error indicates an attempt to send the message and the connection has been aborted by your server. If this happened while connecting to the database, this can be related to using not compatible Connector/J JDBC driver.

    Possible solution: Make sure you've proper libraries/drivers in your CLASSPATH.

  • Software caused connection abort: connect.

    This can happen when there is a problem to connect to the remote. For example due to virus-checker rejecting the remote mail requests.

    Possible solution: Check Virus scan service whether it's blocking the port for the outgoing requests for connections.

  • Software caused connection abort: socket write error.

    Possible solution: Make sure you're writing the correct length of bytes to the stream. So double check what you're sending. See this thread.

  • Connection reset by peer: socket write error / Connection aborted by peer: socket write error

    The application did not check whether keep-alive connection had been timed out on the server side.

    Possible solution: Ensure that the HttpClient is non-null before reading from the connection.E13222_01

  • Connection reset by peer.

    The connection has been terminated by the peer (server).

  • Connection reset.

    The connection has been either terminated by the client or closed by the server end of the connection due to request with the request.

    See: What's causing my Connection reset?

TypeError: 'int' object is not callable

In my case I changed:

return <variable>


return str(<variable>)

try with the following and it must work:


Get height of div with no height set in css

Also make sure the div is currently appended to the DOM and visible.

Spool Command: Do not output SQL statement to file

Exec the query in TOAD or SQL DEVELOPER

---select /*csv*/ username, user_id, created from all_users;

Save in .SQL format in "C" drive

--- x.sql

execute command

---- set serveroutput on
     spool y.csv
     spool off;

How to close TCP and UDP ports via windows command line

You can't close sockets without shutting down the process that owns those sockets. Sockets are owned by the process that opened them. So to find out the process ID (PID) for Unix/Linux. Use netstat like so:

netstat -a -n -p -l

That will print something like:

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address               Foreign Address             State     PID/Program name   
tcp        0      0      *                   LISTEN     1879/sendmail: acce 
tcp        0      0        *                   LISTEN     1860/xinetd         

Where -a prints all sockets, -n shows the port number, -p shows the PID, -l shows only what's listening (this is optional depending on what you're after).

The real info you want is PID. Now we can shutdown that process by doing:

kill 1879

If you are shutting down a service it's better to use:

service sendmail stop

Kill literally kills just that process and any children it owns. Using the service command runs the shutdown script registered in the init.d directory. If you use kill on a service it might not properly start back up because you didn't shut it down properly. It just depends on the service.

Unfortunately, Mac is different from Linux/Unix in this respect. You can't use netstat. Read this tutorial if you're interested in Mac:

And if you're on Windows use TaskManager to kill processes, and services UI to shutdown services. You can use netstat on Windows just like Linux/Unix to identify the PID.

correct way to define class variables in Python

I think this sample explains the difference between the styles:

#!/usr/bin/env python

class MyClass:
    element1 = "Hello"

    def __init__(self):
        self.element2 = "World"

obj = MyClass()

print dir(MyClass)
print "--"
print dir(obj)
print "--"
print obj.element1 
print obj.element2
print MyClass.element1 + " " + MyClass.element2
['__doc__', '__init__', '__module__', 'element1']
['__doc__', '__init__', '__module__', 'element1', 'element2']
Hello World
Traceback (most recent call last):
  File "./", line 17, in <module>
    print MyClass.element2
AttributeError: class MyClass has no attribute 'element2'

element1 is bound to the class, element2 is bound to an instance of the class.

What is "with (nolock)" in SQL Server?

NOLOCK is equivalent to READ UNCOMMITTED, however Microsoft says you should not use it for UPDATE or DELETE statements:

For UPDATE or DELETE statements: This feature will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.

This article applies to SQL Server 2005, so the support for NOLOCK exists if you are using that version. In order to future-proof you code (assuming you've decided to use dirty reads) you could use this in your stored procedures:


What exactly does numpy.exp() do?

exp(x) = e^x where e= 2.718281(approx)

import numpy as np

print ar


[ 2.71828183  7.3890561  20.08553692]

Changing file permission in Python

os.chmod(path, 0444) is the Python command for changing file permissions in Python 2.x. For a combined Python 2 and Python 3 solution, change 0444 to 0o444.

You could always use Python to call the chmod command using subprocess. I think this will only work on Linux though.

import subprocess['chmod', '0444', 'path'])

How can I implement the Iterable interface?

First off:

public class ProfileCollection implements Iterable<Profile> {


return m_Profiles.get(m_ActiveProfile);

Tools to selectively Copy HTML+CSS+JS From A Specific Element of DOM

divclip is an updated version of Florentin Sardan's htmlclipper

with modern enhancements: ES5, HTML5, scoped CSS...

you can programmatically extract a stylized div with:

var html = require("divclip").bySel(".article-body");


Name attribute in @Entity and @Table

@Entity(name = "someThing") => this name will be used to name the Entity
@Table(name = "someThing")  => this name will be used to name a table in DB

So, in the first case your table and entity will have the same name, that will allow you to access your table with the same name as the entity while writing HQL or JPQL.

And in second case while writing queries you have to use the name given in @Entity and the name given in @Table will be used to name the table in the DB.

So in HQL your someThing will refer to otherThing in the DB.

Plot size and resolution with R markdown, knitr, pandoc, beamer

Figure sizes are specified in inches and can be included as a global option of the document output format. For example:

title: "My Document"
    fig_width: 6
    fig_height: 4

And the plot's size in the graphic device can be increased at the chunk level:

```{r, fig.width=14, fig.height=12}          #Expand the plot width to 14 inches

ggplot(aes(x=mycolumn1, y=mycolumn2)) +     #specify the x and y aesthetic
geom_line(size=2) +                         #makes the line thicker
theme_grey(base_size = 25)                  #increases the size of the font

You can also use the out.width and out.height arguments to directly define the size of the plot in the output file:

```{r, out.width="200px", out.height="200px"} #Expand the plot width to 200 pixels

ggplot(aes(x=mycolumn1, y=mycolumn2)) +     #specify the x and y aesthetic
geom_line(size=2) +                         #makes the line thicker
theme_grey(base_size = 25)                  #increases the size of the font

Can I multiply strings in Java to repeat sequences?

No, you can't. However you can use this function to repeat a character.

public String repeat(char c, int times){
    StringBuffer b = new StringBuffer();

    for(int i=0;i &lt; times;i++){

    return b.toString();

Disclaimer: I typed it here. Might have mistakes.

Structuring online documentation for a REST API

That's a very complex question for a simple answer.

You may want to take a look at existing API frameworks, like Swagger Specification (OpenAPI), and services like and

Also, here's an example of the same REST API described, organized and even styled in three different ways. It may be a good start for you to learn from existing common ways.

At the very top level I think quality REST API docs require at least the following:

  • a list of all your API endpoints (base/relative URLs)
  • corresponding HTTP GET/POST/... method type for each endpoint
  • request/response MIME-type (how to encode params and parse replies)
  • a sample request/response, including HTTP headers
  • type and format specified for all params, including those in the URL, body and headers
  • a brief text description and important notes
  • a short code snippet showing the use of the endpoint in popular web programming languages

Also there are a lot of JSON/XML-based doc frameworks which can parse your API definition or schema and generate a convenient set of docs for you. But the choice for a doc generation system depends on your project, language, development environment and many other things.

Android Text over image

There are many ways. You use RelativeLayout or AbsoluteLayout.

With relative, you can have the image align with parent on the left side for example and also have the text align to the parent left too... then you can use margins and padding and gravity on the text view to get it lined where you want over the image.

Best way to use multiple SSH private keys on one client

I had run into this issue a while back, when I had two Bitbucket accounts and wanted to had to store separate SSH keys for both. This is what worked for me.

I created two separate ssh configurations as follows.

    User git
    IdentityFile /Users/username/.ssh/personal
    User git
    IdentityFile /Users/username/.ssh/work

Now when I had to clone a repository from my work account - the command was as follows.

git clone [email protected]:teamname/project.git

I had to modify this command to:

git clone git@**work**

Similarly the clone command from my personal account had to be modified to

git clone

Refer this link for more information.

How do I convert from a money datatype in SQL server?

you could either use

SELECT PARSENAME('$'+ Convert(varchar,Convert(money,@MoneyValue),1),2)


SELECT CurrencyNoDecimals = '$'+ LEFT( CONVERT(varchar, @MoneyValue,1),    
       LEN (CONVERT(varchar, @MoneyValue,1)) - 2)

Java says FileNotFoundException but file exists

Apart from all the other answers mentioned here, you can do one thing which worked for me.

If you are reading the path through Scanner or through command line args, instead of copy pasting the path directly from Windows Explorer just manually type in the path.

It worked for me, hope it helps someone :)

Javascript array search and remove string?


array.splice(array.indexOf(item), 1);

how to delete a specific row in codeigniter?

It will come in the url so you can get it by two ways. Fist one

<td><?php echo anchor('textarea/delete_row', 'DELETE', 'id="$row->id"'); ?></td>
$id = $this->input->get('id');

2nd one.

$id = $this->uri->segment(3);

But in the second method you have to count the no. of segments in the url that on which no. your id come. 2,3,4 etc. then you have to pass. then in the ();

How do I convert hex to decimal in Python?

You could use a literal eval:

>>> ast.literal_eval('0xdeadbeef')

Or just specify the base as argument to int:

>>> int('deadbeef', 16)

A trick that is not well known, if you specify the base 0 to int, then Python will attempt to determine the base from the string prefix:

>>> int("0xff", 0)
>>> int("0o644", 0)
>>> int("0b100", 0)
>>> int("100", 0)

C# Debug - cannot start debugging because the debug target is missing

Application Property

Switch Target framework to 4.5.2 or something higher and bring it back to your original version (example: 4.5) then when you build, it will work.

How to call external url in jquery?

I think the only way is by using internel PHP code like MANOJ and Fernando suggest.

curl post/get in php file on your server --> call this php file with ajax

The PHP file let say (fb.php):

curl_setopt($ch, CURLOPT_URL,$fbUrl);
curl_setopt($ch, CURLOPT_POST, 1);
// POST data here
curl_setopt($ch, CURLOPT_POSTFIELDS,

// receive server response ...
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$server_output = curl_exec ($ch);
echo $server_output;
curl_close ($ch);

Than use AJAX GET to

fb.php?commentmeta=your comment goes here

from your server.

Or do this with simple HTML and JavaScript from externel server:

Message: <input type="text" id="message">
<input type="submit" onclick='PostMessage()'>
function PostMessage() {
var comment = document.getElementById('message').value;

Replacing accented characters php

I found this way to be a good one, without having to worry too much about charsets and arrays, or iconv:

function replace_accents($str) {
   $str = htmlentities($str, ENT_COMPAT, "UTF-8");
   $str = preg_replace('/&([a-zA-Z])(uml|acute|grave|circ|tilde|ring);/','$1',$str);
   return html_entity_decode($str);

AngularJs: Reload page

My solution to avoid the infinite loop was to create another state which have made the redirection:

$stateProvider.state('app.admin.main', {
    url: '/admin/main',
    authenticate: 'admin',
    controller: ($state, $window) => {
      $state.go('app.admin.overview').then(() => {

Get statistics for each group (such as count, mean, etc) using pandas GroupBy?

Swiss Army Knife: GroupBy.describe

Returns count, mean, std, and other useful statistics per-group.

df.groupby(['A', 'B'])['C'].describe()

           count  mean   std   min   25%   50%   75%   max
A   B                                                     
bar one      1.0  0.40   NaN  0.40  0.40  0.40  0.40  0.40
    three    1.0  2.24   NaN  2.24  2.24  2.24  2.24  2.24
    two      1.0 -0.98   NaN -0.98 -0.98 -0.98 -0.98 -0.98
foo one      2.0  1.36  0.58  0.95  1.15  1.36  1.56  1.76
    three    1.0 -0.15   NaN -0.15 -0.15 -0.15 -0.15 -0.15
    two      2.0  1.42  0.63  0.98  1.20  1.42  1.65  1.87

To get specific statistics, just select them,

df.groupby(['A', 'B'])['C'].describe()[['count', 'mean']]

           count      mean
A   B                     
bar one      1.0  0.400157
    three    1.0  2.240893
    two      1.0 -0.977278
foo one      2.0  1.357070
    three    1.0 -0.151357
    two      2.0  1.423148

describe works for multiple columns (change ['C'] to ['C', 'D']—or remove it altogether—and see what happens, the result is a MultiIndexed columned dataframe).

You also get different statistics for string data. Here's an example,

df2 = df.assign(D=list('aaabbccc')).sample(n=100, replace=True)

with pd.option_context('precision', 2):
    display(df2.groupby(['A', 'B'])
               .dropna(how='all', axis=1))

              C                                                   D                
          count  mean       std   min   25%   50%   75%   max count unique top freq
A   B                                                                              
bar one    14.0  0.40  5.76e-17  0.40  0.40  0.40  0.40  0.40    14      1   a   14
    three  14.0  2.24  4.61e-16  2.24  2.24  2.24  2.24  2.24    14      1   b   14
    two     9.0 -0.98  0.00e+00 -0.98 -0.98 -0.98 -0.98 -0.98     9      1   c    9
foo one    22.0  1.43  4.10e-01  0.95  0.95  1.76  1.76  1.76    22      2   a   13
    three  15.0 -0.15  0.00e+00 -0.15 -0.15 -0.15 -0.15 -0.15    15      1   c   15
    two    26.0  1.49  4.48e-01  0.98  0.98  1.87  1.87  1.87    26      2   b   15

For more information, see the documentation.

pandas >= 1.1: DataFrame.value_counts

This is available from pandas 1.1 if you just want to capture the size of every group, this cuts out the GroupBy and is faster.

df.value_counts(subset=['col1', 'col2'])

Minimal Example

# Setup
df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
                          'foo', 'bar', 'foo', 'foo'],
                   'B' : ['one', 'one', 'two', 'three',
                          'two', 'two', 'one', 'three'],
                   'C' : np.random.randn(8),
                   'D' : np.random.randn(8)})

df.value_counts(['A', 'B']) 

A    B    
foo  two      2
     one      2
     three    1
bar  two      1
     three    1
     one      1
dtype: int64

Other Statistical Analysis Tools

If you didn't find what you were looking for above, the User Guide has a comprehensive listing of supported statical analysis, correlation, and regression tools.

Setting up FTP on Amazon Cloud Server

maybe worth mentioning in addition to clone45's answer:

Fixing Write Permissions for Chrooted FTP Users in vsftpd

The vsftpd version that comes with Ubuntu 12.04 Precise does not permit chrooted local users to write by default. By default you will have this in /etc/vsftpd.conf:


In order to allow local users to write, you need to add the following parameter:


Note: Issues with write permissions may show up as following FileZilla errors:

Error: GnuTLS error -15: An unexpected TLS packet was received.
Error: Could not connect to server

Fixing Write Permissions for Chrooted FTP Users in vsftpd
VSFTPd stopped working after update

Design Documents (High Level and Low Level Design Documents)

High-Level Design (HLD) involves decomposing a system into modules, and representing the interfaces & invocation relationships among modules. An HLD is referred to as software architecture.

LLD, also known as a detailed design, is used to design internals of the individual modules identified during HLD i.e. data structures and algorithms of the modules are designed and documented.

Now, HLD and LLD are actually used in traditional Approach (Function-Oriented Software Design) whereas, in OOAD, the system is seen as a set of objects interacting with each other.

As per the above definitions, a high-level design document will usually include a high-level architecture diagram depicting the components, interfaces, and networks that need to be further specified or developed. The document may also depict or otherwise refer to work flows and/or data flows between component systems.

Class diagrams with all the methods and relations between classes come under LLD. Program specs are covered under LLD. LLD describes each and every module in an elaborate manner so that the programmer can directly code the program based on it. There will be at least 1 document for each module. The LLD will contain - a detailed functional logic of the module in pseudo code - database tables with all elements including their type and size - all interface details with complete API references(both requests and responses) - all dependency issues - error message listings - complete inputs and outputs for a module.

How to speed up insertion performance in PostgreSQL

I spent around 6 hours on the same issue today. Inserts go at a 'regular' speed (less than 3sec per 100K) up until to 5MI (out of total 30MI) rows and then the performance sinks drastically (all the way down to 1min per 100K).

I will not list all of the things that did not work and cut straight to the meat.

I dropped a primary key on the target table (which was a GUID) and my 30MI or rows happily flowed to their destination at a constant speed of less than 3sec per 100K.

How to check if a row exists in MySQL? (i.e. check if an email exists in MySQL)

There are multiple ways to check if a value exists in the database. Let me demonstrate how this can be done properly with PDO and mysqli.


PDO is the simpler option. To find out whether a value exists in the database you can use prepared statement and fetchColumn(). There is no need to fetch any data so we will only fetch 1 if the value exists.


// Connection code. 
$options = [
$pdo = new \PDO('mysql:host=localhost;port=3306;dbname=test;charset=utf8mb4', 'testuser', 'password', $options);

// Prepared statement
$stmt = $pdo->prepare('SELECT 1 FROM tblUser WHERE email=?');
$exists = $stmt->fetchColumn(); // either 1 or null

if ($exists) {
    echo 'Email exists in the database.';
} else {
    // email doesn't exist yet

For more examples see: How to check if email exists in the database?


As always mysqli is a little more cumbersome and more restricted, but we can follow a similar approach with prepared statement.


// Connection code
$mysqli = new \mysqli('localhost', 'testuser', 'password', 'test');

// Prepared statement
$stmt = $mysqli->prepare('SELECT 1 FROM tblUser WHERE email=?');
$stmt->bind_param('s', $_POST['email']);
$exists = (bool) $stmt->get_result()->fetch_row(); // Get the first row from result and cast to boolean

if ($exists) {
    echo 'Email exists in the database.';
} else {
    // email doesn't exist yet

Instead of casting the result row(which might not even exist) to boolean, you can also fetch COUNT(1) and read the first item from the first row using fetch_row()[0]

For more examples see: How to check whether a value exists in a database using mysqli prepared statements

Minor remarks

  • If someone suggests you to use mysqli_num_rows(), don't listen to them. This is a very bad approach and could lead to performance issues if misused.
  • Don't use real_escape_string(). This is not meant to be used as a protection against SQL injection. If you use prepared statements correctly you don't need to worry about any escaping.
  • If you want to check if a row exists in the database before you try to insert a new one, then it is better not to use this approach. It is better to create a unique key in the database and let it throw an exception if a duplicate value exists.

How to insert a row in an HTML table body in JavaScript

I think this script is what exactly you need

var t = document.getElementById('myTable');
var r =document.createElement('TR');

How to use LINQ Distinct() with multiple fields

This is my solution, it supports keySelectors of different types:

public static IEnumerable<TSource> DistinctBy<TSource>(this IEnumerable<TSource> source, params Func<TSource, object>[] keySelectors)
    // initialize the table
    var seenKeysTable = keySelectors.ToDictionary(x => x, x => new HashSet<object>());

    // loop through each element in source
    foreach (var element in source)
        // initialize the flag to true
        var flag = true;

        // loop through each keySelector a
        foreach (var (keySelector, hashSet) in seenKeysTable)
            // if all conditions are true
            flag = flag && hashSet.Add(keySelector(element));

        // if no duplicate key was added to table, then yield the list element
        if (flag)
            yield return element;

To use it:

list.DistinctBy(d => d.CategoryId, d => d.CategoryName)

extracting days from a numpy.timedelta64 value

You can convert it to a timedelta with a day precision. To extract the integer value of days you divide it with a timedelta of one day.

>>> x = np.timedelta64(2069211000000000, 'ns')
>>> days = x.astype('timedelta64[D]')
>>> days / np.timedelta64(1, 'D')

Or, as @PhillipCloud suggested, just days.astype(int) since the timedelta is just a 64bit integer that is interpreted in various ways depending on the second parameter you passed in ('D', 'ns', ...).

You can find more about it here.

How to add message box with 'OK' button?

I think there may be problem that you haven't added click listener for ok positive button.

    new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
          //dismiss the dialog  

Python: Number of rows affected by cursor.execute("SELECT ...)

From PEP 249, which is usually implemented by Python database APIs:

Cursor Objects should respond to the following methods and attributes:


This read-only attribute specifies the number of rows that the last .execute*() produced (for DQL statements like 'select') or affected (for DML statements like 'update' or 'insert').

But be careful—it goes on to say:

The attribute is -1 in case no .execute*() has been performed on the cursor or the rowcount of the last operation is cannot be determined by the interface. [7]

Future versions of the DB API specification could redefine the latter case to have the object return None instead of -1.

So if you've executed your statement, and it works, and you're certain your code will always be run against the same version of the same DBMS, this is a reasonable solution.

How to set image for bar button with swift?

Initialize barbuttonItem like following:

let pauseButton = UIBarButtonItem(image: UIImage(named: "big"),
                                  style: .plain,
                                  target: self,
                                  action: #selector(PlaybackViewController.pause))

Sleeping in a batch file

In Notepad, write:

@echo off
set /a WAITTIME=%1+1
PING -n %WAITTIME% > nul

Now save as wait.bat in the folder C:\WINDOWS\System32, then whenever you want to wait, use:

CALL WAIT.bat <whole number of seconds without quotes>

jQuery iframe load() event?

use iframe onload event

$('#theiframe').on("load", function() {

How do I put a border around an Android textview?

setBackground on your xml textview,

add rounded_textview.xml file into your drawable directory.

<shape xmlns:android="" android:shape="rectangle" >
   <solid android:color="@android:color/white" />
   <stroke android:width="2dip" android:color="#4f5g52"/>

set drawable file in textView background.

for each loop in groovy

Your code works fine.

def list = [["c":"d"], ["e":"f"], ["g":"h"]]
Map tmpHM = [1:"second (e:f)", 0:"first (c:d)", 2:"third (g:h)"]

for (objKey in tmpHM.keySet()) {   
    HashMap objHM = (HashMap) list.get(objKey);
    print("objHM: ${objHM}  , ")

prints objHM: [e:f] , objHM: [c:d] , objHM: [g:h] ,


Then click "edit in console", "execute script"

Center image in table td in CSS

Center a div inside td using margin, the trick is to make the div width same as image width.

    <div style="margin: 0 auto; width: 130px">
          <img src="me.jpg" alt="me" style="width: 130px" />

Could not find or load main class org.gradle.wrapper.GradleWrapperMain

In addition to @RaGe's answer may be the situation I faced where i had a global git ignore that was ignoring .jar files and so the gradle wrapper jar was never being committed. Thus I was getting that error on the Jenkins server after an attempted /var/lib/jenkins/my_project/gradlew build. I had to explicitly force an add of the jar and then commit:

git add -f gradle/wrapper/gradle-wrapper.jar

how to get file path from sd card in android

this code helps to get it easily............

Actually in some devices external sdcard default name is showing as extSdCard and for other it is sdcard1. This code snippet helps to find out that exact path and helps to retrive you the path of external device..

String sdpath,sd1path,usbdiskpath,sd0path; 

if(new File("/storage/extSdCard/").exists()) 
  Log.i("Sd Cardext Path",sdpath); 
if(new File("/storage/sdcard1/").exists()) 
  Log.i("Sd Card1 Path",sd1path); 
if(new File("/storage/usbcard1/").exists()) 
  Log.i("USB Path",usbdiskpath); 
if(new File("/storage/sdcard0/").exists()) 
  Log.i("Sd Card0 Path",sd0path); 

How to get the host name of the current machine as defined in the Ansible hosts file?

You can limit the scope of a playbook by changing the hosts header in its plays without relying on your special host label ‘local’ in your inventory. Localhost does not need a special line in inventories.

- name: run on all except local
  hosts: all:!local

Async await in linq select

var inputs = events.Select(async ev => await ProcessEventAsync(ev))
                   .Select(t => t.Result)
                   .Where(i => i != null)

But this seems very weird to me, first of all the use of async and await in the select. According to this answer by Stephen Cleary I should be able to drop those.

The call to Select is valid. These two lines are essentially identical:

events.Select(async ev => await ProcessEventAsync(ev))
events.Select(ev => ProcessEventAsync(ev))

(There's a minor difference regarding how a synchronous exception would be thrown from ProcessEventAsync, but in the context of this code it doesn't matter at all.)

Then the second Select which selects the result. Doesn't this mean the task isn't async at all and is performed synchronously (so much effort for nothing), or will the task be performed asynchronously and when it's done the rest of the query is executed?

It means that the query is blocking. So it is not really asynchronous.

Breaking it down:

var inputs = events.Select(async ev => await ProcessEventAsync(ev))

will first start an asynchronous operation for each event. Then this line:

                   .Select(t => t.Result)

will wait for those operations to complete one at a time (first it waits for the first event's operation, then the next, then the next, etc).

This is the part I don't care for, because it blocks and also would wrap any exceptions in AggregateException.

and is it completely the same like this?

var tasks = await Task.WhenAll(events.Select(ev => ProcessEventAsync(ev)));
var inputs = tasks.Where(result => result != null).ToList();

var inputs = (await Task.WhenAll(events.Select(ev => ProcessEventAsync(ev))))
                                       .Where(result => result != null).ToList();

Yes, those two examples are equivalent. They both start all asynchronous operations (events.Select(...)), then asynchronously wait for all the operations to complete in any order (await Task.WhenAll(...)), then proceed with the rest of the work (Where...).

Both of these examples are different from the original code. The original code is blocking and will wrap exceptions in AggregateException.

Box-Shadow on the left side of the element only

You probably need more blur and a little less spread.

box-shadow: -10px 0px 10px 1px #aaaaaa;

Try messing around with the box shadow generator here until you get your desired effect.

Replacing H1 text with a logo image: best method for SEO and accessibility?

You missed title in <a> element.

<h1 id="logo">
  <a href="#" title="..."><span>Stack Overflow</span></a>

I suggest to put title in <a> element because client would want to know what is the meaning of that image. Because you have set text-indent for the test of <h1> so, that front end user could get information of main logo while they hover on logo.

Javascript / Chrome - How to copy an object from the webkit inspector as code

  1. Right-click an object in Chrome's console and select Store as Global Variable from the context menu. It will return something like temp1 as the variable name.

  2. Chrome also has a copy() method, so copy(temp1) in the console should copy that object to your clipboard.

Copy Javascript Object in Chrome DevTools

Note on Recursive Objects: If you're trying to copy a recursive object, you will get [object Object]. The way out is to copy(JSON.stringify(temp1)) , the object will be fully copied to your clipboard as a valid JSON, so you'd be able to format it as you wish, using one of many resources.

Importing files from different folder

I was faced with the same challenge, especially when importing multiple files, this is how I managed to overcome it.

import os, sys

from os.path import dirname, join, abspath
sys.path.insert(0, abspath(join(dirname(__file__), '..')))

from root_folder import file_name

awk without printing newline

one way

awk '/^\*\*/{gsub("*","");printf "\n"$0" ";next}{printf $0" "}' to-plot.xls

'' is not recognized as an internal or external command, operable program or batch file

When you want to run an executable file from the Command prompt, (cmd.exe), or a batch file, it will:

  • Search the current working directory for the executable file.
  • Search all locations specified in the %PATH% environment variable for the executable file.

If the file isn't found in either of those options you will need to either:

  1. Specify the location of your executable.
  2. Change the working directory to that which holds the executable.
  3. Add the location to %PATH% by apending it, (recommended only with extreme caution).

You can see which locations are specified in %PATH% from the Command prompt, Echo %Path%.

Because of your reported error we can assume that Mobile.exe is not in the current directory or in a location specified within the %Path% variable, so you need to use 1., 2. or 3..

Examples for 1.



"C:\directory path with spaces\My-App\Mobile.exe"

Alternatively you may try:

Start C:\directory_path_without_spaces\My-App\Mobile.exe


Start "" "C:\directory path with spaces\My-App\Mobile.exe"

Where "" is an empty title, (you can optionally add a string between those doublequotes).

Examples for 2.

CD /D C:\directory_path_without_spaces\My-App


CD /D "C:\directory path with spaces\My-App"

You could also use the /D option with Start to change the working directory for the executable to be run by the start command

Start /D C:\directory_path_without_spaces\My-App Mobile.exe


Start "" /D "C:\directory path with spaces\My-App" Mobile.exe

Delete all files of specific type (extension) recursively down a directory using a batch file

You can use wildcards with the del command, and /S to do it recursively.

del /S *.jpg


@BmyGuest asked why a downvoted answer (del /s c:\*.blaawbg) was any different than my answer.

There's a huge difference between running del /S *.jpg and del /S C:\*.jpg. The first command is executed from the current location, whereas the second is executed on the whole drive.

In the scenario where you delete jpg files using the second command, some applications might stop working, and you'll end up losing all your family pictures. This is utterly annoying, but your computer will still be able to run.

However, if you are working on some project, and want to delete all your dll files in myProject\dll, and run the following batch file:

@echo off

REM This short script will only remove dlls from my project... or will it?

cd \myProject\dll
del /S /Q C:\*.dll

Then you end up removing all dll files form your C:\ drive. All of your applications stop working, your computer becomes useless, and at the next reboot you are teleported in the fourth dimension where you will be stuck for eternity.

The lesson here is not to run such command directly at the root of a drive (or in any other location that might be dangerous, such as %windir%) if you can avoid it. Always run them as locally as possible.

Addendum 2

The wildcard method will try to match all file names, in their 8.3 format, and their "long name" format. For example, *.dll will match project.dll and project.dllold, which can be surprising. See this answer on SU for more detailed information.

What are the differences between LDAP and Active Directory?

LDAP sits on top of the TCP/IP stack and controls internet directory access. It is environment agnostic.

AD & ADSI is a COM wrapper around the LDAP layer, and is Windows specific.

You can see Microsoft's explanation here.

Understanding "VOLUME" instruction in DockerFile

To better understand the volume instruction in dockerfile, let us learn the typical volume usage in mysql official docker file implementation.

VOLUME /var/lib/mysql


The /var/lib/mysql is the default location of MySQL that store data files.

When you run test container for test purpose only, you may not specify its mounting point,e.g.

docker run mysql:8

then the mysql container instance will use the default mount path which is specified by the volume instruction in dockerfile. the volumes is created with a very long ID-like name inside the Docker root, this is called "unnamed" or "anonymous" volume. In the folder of underlying host system /var/lib/docker/volumes.


This is very convenient for quick test purposes without the need to specify the mounting point, but still can get best performance by using Volume for data store, not the container layer.

For a formal use, you will need to specify the mount path by using named volume or bind mount, e.g.

docker run  -v /my/own/datadir:/var/lib/mysql mysql:8

The command mounts the /my/own/datadir directory from the underlying host system as /var/lib/mysql inside the container.The data directory /my/own/datadir won't be automatically deleted, even the container is deleted.

Usage of the mysql official image (Please check the "Where to Store Data" section):


Using Python 3 in virtualenv

On Mac I had to do the following to get it to work.

mkvirtualenv --python=/usr/bin/python3 YourEnvNameHere

How to refresh Gridview after pressed a button in

Before data bind change gridview databinding method, assign GridView.EditIndex to -1. It solved the same issue for me :

 gvTypes.EditIndex = -1;

gvTypes is my GridView ID.

How / can I display a console window in Intellij IDEA?

View>Tool Windows>Run

It will show you the console

Xcode 12, building for iOS Simulator, but linking in object file built for iOS, for architecture arm64

After trying a lot useless answers online. This works for me.

First, generates x86_64 for Pod projects!!!!

post_install do |installer|
    installer.pods_project.targets.each do |target|
        target.build_configurations.each do |config|
            config.build_settings['ARCHS'] = "arm64 x86_64"

Second, add "x86_64" for VALID_ARCHS

enter image description here

Is there a command for formatting HTML in the Atom editor?

  1. Go to "Packages" in atom editor.
  2. Then in "Packages" view choose "Settings View".
  3. Choose "Install Packages/Themes".
  4. Search for "Atom Beautify" and install it.

NoClassDefFoundError on Maven dependency

I was able to work around it by running mvn install:install-file with -Dpackaging=class. Then adding entry to POM as described here:

jQuery validation: change default error message

$(function() {


var error_username = false;
var error_password = false;
var error_retype_password = false;
var error_email = false;

$("#form_username").focusout(function() {


$("#form_password").focusout(function() {


$("#form_retype_password").focusout(function() {


$("#form_email").focusout(function() {


function check_username() {

    var username_length = $("#form_username").val().length;
    if(username_length < 5 || username_length > 20) {
        $("#username_error_message").html("Should be between 5-20 characters");
        error_username = true;
    } else {


function check_password() {

    var password_length = $("#form_password").val().length;
    if(password_length < 8) {
        $("#password_error_message").html("At least 8 characters");
        error_password = true;
    } else {


function check_retype_password() {

    var password = $("#form_password").val();
    var retype_password = $("#form_retype_password").val();
    if(password !=  retype_password) {
        $("#retype_password_error_message").html("Passwords don't match");
        error_retype_password = true;
    } else {


function check_email() {

    var pattern = new RegExp(/^[+a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/i);

    if(pattern.test($("#form_email").val())) {
    } else {
        $("#email_error_message").html("Invalid email address");
        error_email = true;


$("#registration_form").submit(function() {
    error_username = false;
    error_password = false;
    error_retype_password = false;
    error_email = false;
    if(error_username == false && error_password == false && error_retype_password == false && error_email == false) {
        return true;
    } else {
        return false;   



How to perform a fade animation on Activity transition?

Just re-posting answer by oleynikd because it's simple and neat

Bundle bundle = ActivityOptionsCompat.makeCustomAnimation(getContext(),
    android.R.anim.fade_in, android.R.anim.fade_out).toBundle(); 
startActivity(intent, bundle);

How to get date representing the first day of a month?

i think normally converts string to MM/DD/YY HH:mm:ss, you would need to use 08/01/2010 00:00:00

Sorry, misunderstood the question, looking to see if you can change the order for strings.

This may be what you want:

declare @test as date

select @test = CONVERT(date, '01/08/2010 00:00:00', 103)
select convert(varchar(15), @test, 106)

Laravel PDOException SQLSTATE[HY000] [1049] Unknown database 'forge'

I did all of them but didn't work, I find out should stop php artisan serve(Ctrl + C) and start php artisan serve again.

Get selected key/value of a combo box using jQuery

<select name="foo" id="foo">
 <option value="1">a</option>
 <option value="2">b</option>
 <option value="3">c</option>
  <input type="button" id="button" value="Button" />
  <script> ("#foo").val() </script>

which returns 1 if you have selected a and so on..

HTML5 Audio Looping

This works and it is a lot easier to toggle that the methods above:

use inline: onended="if($(this).attr('data-loop')){ this.currentTime = 0;; }"

Turn the looping on by $(audio_element).attr('data-loop','1'); Turn the looping off by $(audio_element).removeAttr('data-loop');

How to turn off the Eclipse code formatter for certain sections of Java code?

Not so pretty but works with default settings and for the first line as well:

String query = "" +
    "  FROM ABC          " +
    " WHERE BAR > 4      ";

CSV in Python adding an extra carriage return, on Windows

While @john-machin gives a good answer, it's not always the best approach. For example, it doesn't work on Python 3 unless you encode all of your inputs to the CSV writer. Also, it doesn't address the issue if the script wants to use sys.stdout as the stream.

I suggest instead setting the 'lineterminator' attribute when creating the writer:

import csv
import sys

doc = csv.writer(sys.stdout, lineterminator='\n')

That example will work on Python 2 and Python 3 and won't produce the unwanted newline characters. Note, however, that it may produce undesirable newlines (omitting the LF character on Unix operating systems).

In most cases, however, I believe that behavior is preferable and more natural than treating all CSV as a binary format. I provide this answer as an alternative for your consideration.

How do I remove the old history from a git repository?

As an alternative to rewriting history, consider using git replace as in this article from the Pro Git book. The example discussed involves replacing a parent commit to simulate the beginning of a tree, while still keeping the full history as a separate branch for safekeeping.

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

You could change the @RequestParam type to an Integer and make it not required. This would allow your request to succeed, but it would then be null. You could explicitly set it to your default value in the controller method:

@RequestMapping(value = "/test", method = RequestMethod.POST)
public void test(@RequestParam(value = "i", required=false) Integer i) {
    if(i == null) {
        i = 10;
    // ...

I have removed the defaultValue from the example above, but you may want to include it if you expect to receive requests where it isn't set at all:

select2 onchange event only works once

This is what I am using:

$("#search_code").live('change', function(){

For latest jQuery users, this one should work:


PostgreSQL: export resulting data from SQL query to Excel/CSV

Example with Unix-style file name:

COPY (SELECT * FROM tbl) TO '/var/lib/postgres/myfile1.csv' format csv;

Read the manual about COPY (link to version 8.2).
You have to use an absolute path for the target file. Be sure to double quote file names with spaces. Example for MS Windows:

TO E'"C:\\Documents and Settings\\Tech\Desktop\\myfile1.csv"' format csv;

In PostgreSQL 8.2, with standard_conforming_strings = off per default, you need to double backslashes, because \ is a special character and interpreted by PostgreSQL. Works in any version. It's all in the fine manual:


 The absolute path name of the input or output file. Windows users might need to use an E'' string and double backslashes used as path separators.

Or the modern syntax with standard_conforming_strings = on (default since Postgres 9.1):

COPY tbl  -- short for (SELECT * FROM tbl)
TO '"C:\Documents and Settings\Tech\Desktop\myfile1.csv"' (format csv);

Or you can also use forward slashes for filenames under Windows.

An alternative is to use the meta-command \copy of the default terminal client psql.

You can also use a GUI like pgadmin and copy / paste from the result grid to Excel for small queries.

Closely related answer:

Similar solution for MySQL:

Spring: How to inject a value to static field?

First of all, public static non-final fields are evil. Spring does not allow injecting to such fields for a reason.

Your workaround is valid, you don't even need getter/setter, private field is enough. On the other hand try this:

public void setPrivateName(String privateName) { = privateName;

(works with @Autowired/@Resource). But to give you some constructive advice: Create a second class with private field and getter instead of public static field.

How to launch html using Chrome at "--allow-file-access-from-files" mode?

Depending on the file which will be put into filesystem, as long as that file is not a malware, then that would be safe.

But don't worry to write/read file(s) to File System directory, cause you can tighten that directory security (include it's inheritance) by give a proper access right and security restriction. eg: read/write/modify.

By default, File System, Local Storage, and Storage directory are located on "\Users[Current User]\AppData\Local\Google\Chrome\User Data\Default" directory.

However you can customize it by using "--user-data-dir" flag.

And this is a sample:

"C:\Program Files (x86)\Google\Application\chrome.exe" --user-data-dir="C:\Chrome_Data\OO7" --allow-file-access-from-files

Hope this helps anyone.

How to spyOn a value property (rather than a method) with Jasmine

Suppose there is a method like this that needs testing The src property of the tiny image needs checking

function reportABCEvent(cat, type, val) {
                var i1 = new Image(1, 1);
                var link = getABC('creosote');
                    link += "&category=" + String(cat);
                    link += "&event_type=" + String(type);
                    link += "&event_value=" + String(val);
                    i1.src = link;

The spyOn() below causes the "new Image" to be fed the fake code from the test the spyOn code returns an object that only has a src property

As the variable "hook" is scoped to be visible in the fake code in the SpyOn and also later after the "reportABCEvent" is called

describe("", function() {
    it("ABC events create an image request", function() {
    var hook={};
    spyOn(window, 'Image').andCallFake( function(x,y) {
          hook={ src: {} }
          return hook;
      reportABCEvent('testa', 'testb', 'testc');

This is for jasmine 1.3 but might work on 2.0 if the "andCallFake" is altered to the 2.0 name

How do I specify "close existing connections" in sql script

You can disconnect everyone and roll back their transactions with:

alter database [MyDatbase] set single_user with rollback immediate

After that, you can safely drop the database :)

How to make div appear in front of another?

Use the CSS z-index property. Elements with a greater z-index value are positioned in front of elements with smaller z-index values.

Note that for this to work, you also need to set a position style (position:absolute, position:relative, or position:fixed) on both/all of the elements you want to order.

What causes a Python segmentation fault?

Looks like you are out of stack memory. You may want to increase it as Davide stated. To do it in python code, you would need to run your "main()" using threading:

def main():
    pass # write your code here

sys.setrecursionlimit(2097152)    # adjust numbers
threading.stack_size(134217728)   # for your needs

main_thread = threading.Thread(target=main)

Source: c1729's post on codeforces. Runing it with PyPy is a bit trickier.

How do I instantiate a Queue object in java?

Queue in Java is defined as an interface and many ready-to-use implementation is present as part of JDK release. Here are some: LinkedList, Priority Queue, ArrayBlockingQueue, ConcurrentLinkedQueue, Linked Transfer Queue, Synchronous Queue etc.

SO You can create any of these class and hold it as Queue reference. for example

import java.util.LinkedList;
import java.util.Queue;

public class QueueExample {

 public static void main (String[] args) {
  Queue que = new LinkedList();
  System.out.println("Queue Print:: " + que);
  String head = que.element();
  System.out.println("Head element:: " + head);
  String element1 = que.poll();
  System.out.println("Removed Element:: " + element1);
  System.out.println("Queue Print after poll:: " + que);
  String element2 = que.remove();
  System.out.println("Removed Element:: " + element2);
  System.out.println("Queue Print after remove:: " + que);  

You can also implement your own custom Queue implementing Queue interface.

notifyDataSetChange not working from custom adapter

If adapter is set to AutoCompleteTextView then notifyDataSetChanged() doesn't work.

Need this to update adapter:

myAutoCompleteAdapter = new ArrayAdapter<String>(MainActivity.this, 
        android.R.layout.simple_dropdown_item_1line, myList);



How to get a substring between two strings in PHP?

Here's a function

function getInnerSubstring($string, $boundstring, $trimit=false) {
    $res = false;
    $bstart = strpos($string, $boundstring);
    if ($bstart >= 0) {
        $bend = strrpos($string, $boundstring);
        if ($bend >= 0 && $bend > $bstart)
            $res = substr($string, $bstart+strlen($boundstring), $bend-$bstart-strlen($boundstring));
    return $trimit ? trim($res) : $res;

Use it like

$string = "foo I wanna a cake foo";
$substring = getInnerSubstring($string, "foo");

echo $substring;

Output (note that it returns spaces in front and at the and of your string if exist)

I wanna a cake

If you want to trim result use function like

$substring = getInnerSubstring($string, "foo", true);

Result: This function will return false if $boundstring was not found in $string or if $boundstring exists only once in $string, otherwise it returns substring between first and last occurrence of $boundstring in $string.


Android studio 3.0: Unable to resolve dependency for :app@dexOptions/compileClasspath': Could not resolve project :animators

Here is how I solved my problem:

instead of

compile project(':library_name')
compile project(':library_name')

in app gradle I have used

implementation project(':library_name')
implementation project(':library_name')

And in my build types for example

demoTest {

I added this line

demoTest {
   matchingFallbacks = ['debug', 'release']

Python exit commands - why so many and when should each be used?

Different Means of Exiting


  • Exit the process without calling the cleanup handlers.


  • a clean exit without any errors / problems.


  • There was some issue / error / problem and that is why the program is exiting.


  • When the system and python shuts down; it means less memory is being used after the program is run.


  • Closes the python file.


Basically they all do the same thing, however, it also depends on what you are doing it for.

I don't think you left anything out and I would recommend getting used to quit() or exit().

You would use sys.exit() and os._exit() mainly if you are using big files or are using python to control terminal.

Otherwise mainly use exit() or quit().

How can I list all tags for a Docker image on a remote registry?

To view all available tags in a browser:<username>/<image_name>/tags


Or, you can get a json response using this endpoint:

MVC 4 client side validation not working

I had the same problem. It seems that the unobtrusive validation scripts were not loaded (see screenshot at the end). I fixed it by adding at the end of _Layout.cshtml


The end result:

   @RenderSection("scripts", required: false)

Except for my pretty standard CRUD views everything is Visual studio project template defaults.

Loaded scripts after fixing the problem: enter image description here

Bootstrap 3: Offset isn't working?

Which version of bootstrap are you using? The early versions of Bootstrap 3 (3.0, 3.0.1) didn't work with this functionality.

col-md-offset-0 should be working as seen in this bootstrap example found here (

<div class="row">
   <div class="col-sm-5 col-md-6">.col-sm-5 .col-md-6</div>
   <div class="col-sm-5 col-sm-offset-2 col-md-6 col-md-offset-0">.col-sm-5 .col-sm-offset-2 .col-md-6 .col-md-offset-0</div>

How many concurrent requests does a single Flask process receive?

No- you can definitely handle more than that.

Its important to remember that deep deep down, assuming you are running a single core machine, the CPU really only runs one instruction* at a time.

Namely, the CPU can only execute a very limited set of instructions, and it can't execute more than one instruction per clock tick (many instructions even take more than 1 tick).

Therefore, most concurrency we talk about in computer science is software concurrency. In other words, there are layers of software implementation that abstract the bottom level CPU from us and make us think we are running code concurrently.

These "things" can be processes, which are units of code that get run concurrently in the sense that each process thinks its running in its own world with its own, non-shared memory.

Another example is threads, which are units of code inside processes that allow concurrency as well.

The reason your 4 worker processes will be able to handle more than 4 requests is that they will fire off threads to handle more and more requests.

The actual request limit depends on HTTP server chosen, I/O, OS, hardware, network connection etc.

Good luck!

*instructions are the very basic commands the CPU can run. examples - add two numbers, jump from one instruction to another

How to write a multiline command?

In the Windows Command Prompt the ^ is used to escape the next character on the command line. (Like \ is used in strings.) Characters that need to be used in the command line as they are should have a ^ prefixed to them, hence that's why it works for the newline.

For reference the characters that need escaping (if specified as command arguments and not within quotes) are: &|()

So the equivalent of your linux example would be (the More? being a prompt):

C:\> dir ^
More? C:\Windows

create table with sequence.nextval in oracle

You can use Oracle's SQL Developer tool to do that (My Oracle DB version is 11). While creating a table choose Advanced option and click on the Identity Column tab at the bottom and from there choose Column Sequence. This will generate a AUTO_INCREMENT column (Corresponding Trigger and Squence) for you.

Converting <br /> into a new line for use in a text area


$var1 = "Line 1 info blah blah <br /> Line 2 info blah blah";
$var1 = str_replace("<br />", "\n", $var1);


<textarea><?php echo $var1; ?></textarea>

IntelliJ and Tomcat.. Howto..?

In Netbeans you can right click on the project and run it, but in IntelliJ IDEA you have to select the index.jsp file or the welcome file to run the project.

this is because Netbeans generate the following tag in web.xml and IntelliJ do not.


Angular 2 Sibling Component Communication

Behaviour subjects. I wrote a blog about that.

import { BehaviorSubject } from 'rxjs/BehaviorSubject';
private noId = new BehaviorSubject<number>(0); 
  defaultId = this.noId.asObservable();

newId(urlId) {; 

In this example i am declaring a noid behavior subject of type number. Also it is an observable. And if "something happend" this will change with the new(){} function.

So, in the sibling's components, one will call the function, to make the change, and the other one will be affected by that change, or vice-versa.

For example, I get the id from the URL and update the noid from the behavior subject.

public getId () {
  const id = +this.route.snapshot.paramMap.get('id'); 
  return id; 

ngOnInit(): void { 
 const id = +this.getId ();

And from the other side, I can ask if that ID is "what ever i want" and make a choice after that, in my case if i want to delte a task, and that task is the current url, it have to redirect me to the home:

delete(task: Task): void { 
  //we save the id , cuz after the delete function, we  gonna lose it 
  const oldId =; 
      .subscribe(task => { //we call the defaultId function from task.service.
        this.taskService.defaultId //here we are subscribed to the urlId, which give us the id from the view task 
                 .subscribe(urlId => {
            this.urlId = urlId ;
                  if (oldId == urlId ) { 

Oracle 11g SQL to get unique values in one column of a multi-column query

select person, language     
from table A     
group by person, language  

will return unique rows

Get array elements from index to end

The [:-1] removes the last element. Instead of




You can read up on Python slicing notation here: Explain Python's slice notation

NumPy slicing is an extension of that. The NumPy tutorial has some coverage: Indexing, Slicing and Iterating.

Why this line xmlns:android="" must be the first in the layout xml file?

In XML, xmlns declares a Namespace. In fact, when you do:

<LinearLayout android:id>

Instead of calling android:id, the xml will use to be unique. Generally this page doesn't exist (it's a URI, not a URL), but sometimes it is a URL that explains the used namespace.

The namespace has pretty much the same uses as the package name in a Java application.

Here is an explanation.

Uniform Resource Identifier (URI)

A Uniform Resource Identifier (URI) is a string of characters which identifies an Internet Resource.

The most common URI is the Uniform Resource Locator (URL) which identifies an Internet domain address. Another, not so common type of URI is the Universal Resource Name (URN).

In our examples we will only use URLs.

How can I enable the Windows Server Task Scheduler History recording?

As noted earlier, there is an option to turn on or off History provided you open up task manager under the elevated "Administrator" mode (right click on the Task Scheduler program/shortcut and choose "Run As Administrator"). Then under "Tasks" is your spot to stop or start History.

How can I debug javascript on Android?

You can try "javascript-compiler-deva" from npm library by running "npm install javascript-compiler-deva" command and then running the using "node compiler.js".

It creates a server at port 8888. You can then hit "http://localhost:8888" and enter your JavaScript code and can see the result of any JavaScript code including "console.log" in phone browser itself.

It is also hosted in ""

Java File - Open A File And Write To It

To expand upon Mr. Eels comment, you can do it like this:

    File file = new File("C:\\A.txt");
    FileWriter writer;
    try {
        writer = new FileWriter(file, true);
        PrintWriter printer = new PrintWriter(writer);
    } catch (IOException e) {
        // TODO Auto-generated catch block

Don't say we ain't good to ya!

How to manually install a pypi module without pip/easy_install?

  1. Download the package
  2. unzip it if it is zipped
  3. cd into the directory containing
  4. If there are any installation instructions contained in documentation contianed herein, read and follow the instructions OTHERWISE
  5. type in python install

You may need administrator privileges for step 5. What you do here thus depends on your operating system. For example in Ubuntu you would say sudo python install

EDIT- thanks to kwatford (see first comment)

To bypass the need for administrator privileges during step 5 above you may be able to make use of the --user flag. In this way you can install the package only for the current user.

The docs say:

Files will be installed into subdirectories of site.USER_BASE (written as userbase hereafter). This scheme installs pure Python modules and extension modules in the same location (also known as site.USER_SITE). Here are the values for UNIX, including Mac OS X:

More details can be found here:

How does += (plus equal) work?

You have to know that:

  • Assignment operators syntax is: variable = expression;

    For this reason 1 += 2 -> 1 = 1 + 2 is not a valid syntax as the left operand isn't a variable. The error in this case is ReferenceError: invalid assignment left-hand side.

  • x += y is the short form for x = x + y, where x is the variable and x + y the expression.

    The result of the sum is 15.

      sum = 0;
      sum = sum + 1; // 1
      sum = sum + 2; // 3
      sum = sum + 3; // 6
      sum = sum + 4; // 10
      sum = sum + 5; // 15

Other assignment operator shortcuts works the same way (relatively to the standard operations they refer to). .

How is the default max Java heap size determined?

This is changed in Java 6 update 18.

Assuming that we have more than 1 GB of physical memory (quite common these days), it's always 1/4th of your physical memory for the server vm.

Change Schema Name Of Table In SQL

Be very very careful renaming objects in sql. You can cause dependencies to fail if you are not fully away with what you are doing. Having said that this works easily(too much so) for renaming things provided you have access proper on the environment:

exec sp_rename 'Nameofobject', 'ReNameofobject'

Comparison of full text search engine - Lucene, Sphinx, Postgresql, MySQL?

I'm looking at PostgreSQL full-text search right now, and it has all the right features of a modern search engine, really good extended character and multilingual support, nice tight integration with text fields in the database.

But it doesn't have user-friendly search operators like + or AND (uses & | !) and I'm not thrilled with how it works on their documentation site. While it has bolding of match terms in the results snippets, the default algorithm for which match terms is not great. Also, if you want to index rtf, PDF, MS Office, you have to find and integrate a file format converter.

OTOH, it's way better than the MySQL text search, which doesn't even index words of three letters or fewer. It's the default for the MediaWiki search, and I really think it's no good for end-users:

In all cases I've seen, Lucene/Solr and Sphinx are really great. They're solid code and have evolved with significant improvements in usability, so the tools are all there to make search that satisfies almost everyone.

for SHAILI - SOLR includes the Lucene search code library and has the components to be a nice stand-alone search engine.

How can I add a class attribute to an HTML element generated by MVC's HTML Helpers?

In order to create an anonymous type (or any type) with a property that has a reserved keyword as its name in C#, you can prepend the property name with an at sign, @:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new { @class = "myclass"})

For VB.NET this syntax would be accomplished using the dot, ., which in that language is default syntax for all anonymous types:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new with { .class = "myclass" })

How many times does each value appear in a column?

I second Dave's idea. I'm not always fond of pivot tables, but in this case they are pretty straightforward to use.

Here are my results:

Enter image description here

It was so simple to create it that I have even recorded a macro in case you need to do this with VBA:

Sub Macro2()
' Macro2 Macro

    ActiveWorkbook.PivotCaches.Create(SourceType:=xlDatabase, SourceData:= _
        "Table1", Version:=xlPivotTableVersion14).CreatePivotTable TableDestination _
        :="Sheet3!R3C7", TableName:="PivotTable4", DefaultVersion:= _
    Cells(3, 7).Select
    With ActiveSheet.PivotTables("PivotTable4").PivotFields("DATA")
        .Orientation = xlRowField
        .Position = 1
    End With
    ActiveSheet.PivotTables("PivotTable4").AddDataField ActiveSheet.PivotTables( _
        "PivotTable4").PivotFields("DATA"), "Count of DATA", xlCount
End Sub

connecting MySQL server to NetBeans

I just had the same issue with Netbeans 8.2 and trying to connect to mySQL server on a Mac OS machine. The only thing that worked for me was to add the following to the url of the connection string: &serverTimezone=UTC (or if you are connecting via Hibernate.cfg.xml then escape the & as &) Not surprisingly I found the solution on this stack overflow post also:

MySQL JDBC Driver 5.1.33 - Time Zone Issue

Best Regards, Claudio

Remove first 4 characters of a string with PHP

You could use the substr function to return a substring starting from the 5th character:

$str = "The quick brown fox jumps over the lazy dog."
$str2 = substr($str, 4); // "quick brown fox jumps over the lazy dog."

How do you format an unsigned long long int using printf?

Non-standard things are always strange :)

for the long long portion under GNU it's L, ll or q

and under windows I believe it's ll only

?: ?? Operators Instead Of IF|ELSE

The ternary operator RETURNS one of two values. Or, it can execute one of two statements based on its condition, but that's generally not a good idea, as it can lead to unintended side-effects.

bar ? () : baz();

In this case, the () does nothing, while baz does something. But you've only made the code less clear. I'd go for more verbose code that's clearer and easier to maintain.

Further, this makes little sense at all:

var foo = bar ? () : baz();

since () has no return type (it's void) and baz has a return type that's unknown at the point of call in this sample. If they don't agree, the compiler will complain, and loudly.

dataframe: how to groupBy/count then filter on count in Scala

So, is that a behavior to expect, a bug

Truth be told I am not sure. It looks like parser is interpreting count not as a column name but a function and expects following parentheses. Looks like a bug or at least a serious limitation of the parser.

is there a canonical way to go around?

Some options have been already mentioned by Herman and mattinbits so here more SQLish approach from me:

import org.apache.spark.sql.functions.count

df.groupBy("x").agg(count("*").alias("cnt")).where($"cnt"  > 2)

Check if boolean is true?

The first example nearly always wins in my book:


It's shorter and more concise. Why add an extra check to something when it's absolutely not needed? Just wasting cycles...

I do agree, though, that sometimes the more verbose syntax makes things more readable (which is ultimately more important as long as performance is acceptable) in situations where variables are poorly named.

How do I output an ISO 8601 formatted string in JavaScript?

I would just use this small extension to Date -

var date = new Date(msSinceEpoch);
date.format("isoDateTime"); // 2007-06-09T17:46:21

UnicodeEncodeError: 'ascii' codec can't encode character u'\xef' in position 0: ordinal not in range(128)

An easy solution to overcome this problem is to set your default encoding to utf8. Follow is an example

import sys


React - How to get parameter value from query string?

If your Router is like this

<Route exact path="/category/:id" component={ProductList}/>

You will get that id like this

Caesar Cipher Function in Python

def encrypt(text,shift):
    INPUT: text as a string and an integer for the shift value.
    OUTPUT: The shifted text after being run through the Caeser cipher.

    # Create a placeholder list
    encrypted_text = list(range(len(text)))

    alphabet = string.ascii_lowercase

    # Create shifted alphabet
    first_half = alphabet[:shift]
    second_half = alphabet[shift:]
    shifted_alphabet = second_half+first_half

    for i,letter in enumerate(text.lower()):

        # Check for spaces or punctuation
        if letter in alphabet:
            # Find the original index position
            original_index = alphabet.index(letter)

            # Shifted letter
            new_letter = shifted_alphabet[original_index]

            encrypted_text[i] = new_letter

        # Punctuation or space
            encrypted_text[i] = letter

    return ''.join(encrypted_text)

How to send POST request?

If you really want to handle with HTTP using Python, I highly recommend Requests: HTTP for Humans. The POST quickstart adapted to your question is:

>>> import requests
>>> r ="", data={'number': 12524, 'type': 'issue', 'action': 'show'})
>>> print(r.status_code, r.reason)
200 OK
>>> print(r.text[:300] + '...')

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="" xml:lang="en" lang="en">
Issue 12524: change httplib docs POST example - Python tracker

<link rel="shortcut i...

Open text file and program shortcut in a Windows batch file

Try using:

@ECHO off
ECHO Hello World!

START /MAX D:\SA\pro\hello.txt

Purpose of installing Twitter Bootstrap through npm?

  1. Use npm/bower to install bootstrap if you want to recompile it/change less files/test. With grunt it would be easier to do this, as shown on If you only want to add precompiled libraries feel free to manually include files to project.

  2. No, you have to do this by yourself or use separate grunt tool. For example 'grunt-contrib-concat' How to concatenate and minify multiple CSS and JavaScript files with Grunt.js (0.3.x)

How to check whether Kafka Server is running?

You can install Kafkacat tool on your machine

For example on Ubuntu You can install it using

apt-get install kafkacat

once kafkacat is installed then you can use following command to connect it

kafkacat -b <your-ip-address>:<kafka-port> -t test-topic
  • Replace <your-ip-address> with your machine ip
  • <kafka-port> can be replaced by the port on which kafka is running. Normally it is 9092

once you run the above command and if kafkacat is able to make the connection then it means that kafka is up and running

Git Pull is Not Possible, Unmerged Files

Solved, using the following command set:

git reset --hard
git pull --rebase
git rebase --skip
git pull

The trick is to rebase the changes... We had some trouble rebasing one trivial commit, and so we simply skipped it using git rebase --skip (after having copied the files).

Remove Datepicker Function dynamically

Just bind the datepicker to a class rather than binding it to the id . Remove the class when you want to revoke the datepicker...

$("#ddlSearchType").change(function () { 
  if ($(this).val() == "Required Date" || $(this).val() == "Submitted Date")                   { 
  } else { 

AngularJS Multiple ng-app within a page

You can use angular.bootstrap() directly... the problem is you lose the benefits of directives.

First you need to get a reference to the HTML element in order to bootstrap it, which means your code is now coupled to your HTML.

Secondly the association between the two is not as apparent. With ngApp you can clearly see what HTML is associated with what module and you know where to look for that information. But angular.bootstrap() could be invoked from anywhere in your code.

If you are going to do it at all the best way would be by using a directive. Which is what I did. It's called ngModule. Here is what your code would look like using it:

<!DOCTYPE html>
        <script src="angular.js"></script>
        <script src=""></script>
          var moduleA = angular.module("MyModuleA", []);
          moduleA.controller("MyControllerA", function($scope) {
              $ = "Bob A";

          var moduleB = angular.module("MyModuleB", []);
          moduleB.controller("MyControllerB", function($scope) {
              $ = "Steve B";
        <div ng-modules="MyModuleA, MyModuleB">
            <h1>Module A, B</h1>
            <div ng-controller="MyControllerA">
            <div ng-controller="MyControllerB">

        <div ng-module="MyModuleB">
            <h1>Just Module B</h1>
            <div ng-controller="MyControllerB">

You can get the source code for it at:

It's implemented in the same way as ngApp. It simply calls angular.bootstrap() behind the scenes.

Is there a reason for C#'s reuse of the variable in a foreach?

What you are asking is thoroughly covered by Eric Lippert in his blog post Closing over the loop variable considered harmful and its sequel.

For me, the most convincing argument is that having new variable in each iteration would be inconsistent with for(;;) style loop. Would you expect to have a new int i in each iteration of for (int i = 0; i < 10; i++)?

The most common problem with this behavior is making a closure over iteration variable and it has an easy workaround:

foreach (var s in strings)
    var s_for_closure = s;
    query = query.Where(i => i.Prop == s_for_closure); // access to modified closure

My blog post about this issue: Closure over foreach variable in C#.


I solved the rowlock problem in a completely different way. I realized that sql server was not able to manage such a lock in a satisfying way. I choosed to solve this from a programatically point of view by the use of a mutex... waitForLock... releaseLock...

Can't build create-react-app project with custom PUBLIC_URL

If the other answers aren't working for you, there's also a homepage field in package.json. After running npm run build you should get a message like the following:

The project was built assuming it is hosted at the server root.
To override this, specify the homepage in your package.json.
For example, add this to build it for GitHub Pages:

  "homepage" : "",

You would just add it as one of the root fields in package.json, e.g.

  // ...
  "scripts": {
    // ...
  "homepage": ""

When it's successfully set, either via homepage or PUBLIC_URL, you should instead get a message like this:

The project was built assuming it is hosted at
You can control this with the homepage field in your package.json.

Regex to check whether a string contains only numbers

^[0-9]$ a regular expression matching any single digit, so 1 will return true but 123 will return false.

If you add the * quantifier,


the expression will match arbitrary length strings of digits and 123 will return true. (123f will still return false).

Be aware that technically an empty string is a 0-length string of digits, and so it will return true using ^[0-9]*$ If you want to only accept strings containing 1 or more digits, use + instead of *


As the many others have pointed out, there are more than a few ways to achieve this, but I felt like it was appropriate to point out that the code in the original question only requires a single additional character to work as intended.

Finding CN of users in Active Directory

You could try my Beavertail ADSI browser - it should show you the current AD tree, and from it, you should be able to figure out the path and all.

alt text

Or if you're on .NET 3.5, using the System.DirectoryServices.AccountManagement namespace, you could also do it programmatically:

PrincipalContext ctx = new PrincipalContext(ContextType.Domain);

This would create a basic, default domain context and you should be able to peek at its properties and find a lot of stuff from it.


UserPrincipal myself = UserPrincipal.Current;

This will give you a UserPrincipal object for yourself, again, with a ton of properties to inspect. I'm not 100% sure what you're looking for - but you most likely will be able to find it on the context or the user principal somewhere!

Remove Fragment Page from ViewPager in Android

The solution by Louth was not enough to get things working for me, as the existing fragments were not getting destroyed. Motivated by this answer, I found that the solution is to override the getItemId(int position) method of FragmentPagerAdapter to give a new unique ID whenever there has been a change in the expected position of a Fragment.

Source Code:

private class MyPagerAdapter extends FragmentPagerAdapter {

    private TextProvider mProvider;
    private long baseId = 0;

    public MyPagerAdapter(FragmentManager fm, TextProvider provider) {
        this.mProvider = provider;

    public Fragment getItem(int position) {
        return MyFragment.newInstance(mProvider.getTextForPosition(position));

    public int getCount() {
        return mProvider.getCount();

    //this is called when notifyDataSetChanged() is called
    public int getItemPosition(Object object) {
        // refresh all fragments when data set changed
        return PagerAdapter.POSITION_NONE;

    public long getItemId(int position) {
        // give an ID different from position when position has been changed
        return baseId + position;

     * Notify that the position of a fragment has been changed.
     * Create a new ID for each position to force recreation of the fragment
     * @param n number of items which have been changed
    public void notifyChangeInPosition(int n) {
        // shift the ID returned by getItemId outside the range of all previous fragments
        baseId += getCount() + n;

Now, for example if you delete a single tab or make some change to the order, you should call notifyChangeInPosition(1) before calling notifyDataSetChanged(), which will ensure that all the Fragments will be recreated.

Why this solution works

Overriding getItemPosition():

When notifyDataSetChanged() is called, the adapter calls the notifyChanged() method of the ViewPager which it is attached to. The ViewPager then checks the value returned by the adapter's getItemPosition() for each item, removing those items which return POSITION_NONE (see the source code) and then repopulating.

Overriding getItemId():

This is necessary to prevent the adapter from reloading the old fragment when the ViewPager is repopulating. You can easily understand why this works by looking at the source code for instantiateItem() in FragmentPagerAdapter.

    final long itemId = getItemId(position);

    // Do we already have this fragment?
    String name = makeFragmentName(container.getId(), itemId);
    Fragment fragment = mFragmentManager.findFragmentByTag(name);
    if (fragment != null) {
        if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
    } else {
        fragment = getItem(position);
        if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
        mCurTransaction.add(container.getId(), fragment,
                makeFragmentName(container.getId(), itemId));

As you can see, the getItem() method is only called if the fragment manager finds no existing fragments with the same Id. To me it seems like a bug that the old fragments are still attached even after notifyDataSetChanged() is called, but the documentation for ViewPager does clearly state that:

Note this class is currently under early design and development. The API will likely change in later updates of the compatibility library, requiring changes to the source code of apps when they are compiled against the newer version.

So hopefully the workaround given here will not be necessary in a future version of the support library.

Open fancybox from function

Here is working code as per the author's Tips & Tricks blog post, put it in document ready:


This triggers the smaller version of the currently displayed image or content, as if you had clicked on it manually. It avoids initializing the Fancybox again, but instead keeps the parameters you initialized it with on document ready. If you need to do something different when opening the box with a separate button compared to clicking on the box, you will need the parameters, but for many, this will be what they were looking for.

Differences between Lodash and Underscore.js

If, like me, you were expecting a list of usage differences between Underscore.js and Lodash, there's a guide for migrating from Underscore.js to Lodash.

Here's the current state of it for posterity:

  • Underscore _.any is Lodash _.some
  • Underscore _.all is Lodash _.every
  • Underscore _.compose is Lodash _.flowRight
  • Underscore _.contains is Lodash _.includes
  • Underscore _.each doesn’t allow exiting by returning false
  • Underscore _.findWhere is Lodash _.find
  • Underscore _.flatten is deep by default while Lodash is shallow
  • Underscore _.groupBy supports an iteratee that is passed the parameters (value, index, originalArray), while in Lodash, the iteratee for _.groupBy is only passed a single parameter: (value).
  • Underscore.js _.indexOf with third parameter undefined is Lodash _.indexOf
  • Underscore.js _.indexOf with third parameter true is Lodash _.sortedIndexOf
  • Underscore _.indexBy is Lodash _.keyBy
  • Underscore _.invoke is Lodash _.invokeMap
  • Underscore _.mapObject is Lodash _.mapValues
  • Underscore _.max combines Lodash _.max & _.maxBy
  • Underscore _.min combines Lodash _.min & _.minBy
  • Underscore _.sample combines Lodash _.sample & _.sampleSize
  • Underscore _.object combines Lodash _.fromPairs and _.zipObject
  • Underscore _.omit by a predicate is Lodash _.omitBy
  • Underscore _.pairs is Lodash _.toPairs
  • Underscore _.pick by a predicate is Lodash _.pickBy
  • Underscore _.pluck is Lodash
  • Underscore _.sortedIndex combines Lodash _.sortedIndex & _.sortedIndexOf
  • Underscore _.uniq by an iteratee is Lodash _.uniqBy
  • Underscore _.where is Lodash _.filter
  • Underscore _.isFinite doesn’t align with Number.isFinite
    (e.g. _.isFinite('1') returns true in Underscore.js, but false in Lodash)
  • Underscore _.matches shorthand doesn’t support deep comparisons
    (e.g., _.filter(objects, { 'a': { 'b': 'c' } }))
  • Underscore = 1.7 & Lodash _.template syntax is
    _.template(string, option)(data)
  • Lodash _.memoize caches are Map like objects
  • Lodash doesn’t support a context argument for many methods in favor of _.bind
  • Lodash supports implicit chaining, lazy chaining, & shortcut fusion
  • Lodash split its overloaded _.head, _.last,, & _.initial out into
    _.take, _.takeRight, _.drop, & _.dropRight
    (i.e. _.head(array, 2) in Underscore.js is _.take(array, 2) in Lodash)

What is REST call and how to send a REST call?

REST is somewhat of a revival of old-school HTTP, where the actual HTTP verbs (commands) have semantic meaning. Til recently, apps that wanted to update stuff on the server would supply a form containing an 'action' variable and a bunch of data. The HTTP command would almost always be GET or POST, and would be almost irrelevant. (Though there's almost always been a proscription against using GET for operations that have side effects, in reality a lot of apps don't care about the command used.)

With REST, you might instead PUT /profiles/cHao and send an XML or JSON representation of the profile info. (Or rather, I would -- you would have to update your own profile. :) That'd involve logging in, usually through HTTP's built-in authentication mechanisms.) In the latter case, what you want to do is specified by the URL, and the request body is just the guts of the resource involved. has some details.

Using command line arguments in VBscript

Set args = Wscript.Arguments

For Each arg In args
  Wscript.Echo arg

From a command prompt, run the script like this:

CSCRIPT MyScript.vbs 1 2 A B "Arg with spaces"

Will give results like this:

Arg with spaces

Disable output buffering

Variant that works without crashing (at least on win32; python 2.7, ipython 0.12) then called subsequently (multiple times):

def DisOutBuffering():
    if == '<stdout>':
        sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

    if == '<stderr>':
        sys.stderr = os.fdopen(sys.stderr.fileno(), 'w', 0)

Java - get index of key in HashMap?

The HashMap has no defined ordering of keys.

Ternary operator in AngularJS templates

This answer predates version 1.1.5 where a proper ternary in the $parse function wasn't available. Use this answer if you're on a lower version, or as an example of filters:

angular.module('myApp.filters', [])
  .filter('conditional', function() {
    return function(condition, ifTrue, ifFalse) {
      return condition ? ifTrue : ifFalse;

And then use it as

<i ng-class="checked | conditional:'icon-check':'icon-check-empty'"></i>

How can I permanently enable line numbers in IntelliJ?

Just an update for Android Studio 1.5.1 on Windows:

Go to File -> Settings -> follow picture enter image description here

Centering elements in jQuery Mobile

jQuery Mobile doesn't seem to have a css class to center elements (I searched through its css).

But you can write your own additional css.

Try creating your own:

  margin: 0 auto;

example HTML:

<div data-role="button" class="center-button">button text</div>

and see what happens. You might need to set text-align to center in the wrapping tag, so this might work better:

  text-align: center;
.center-wrapper * {
  margin: 0 auto;

example HTML:

<div class="center-wrapper">
  <div data-role="button">button text</div>

Deny access to one specific folder in .htaccess

You can also put this IndexIgnore * at your root .htaccess file to disable file listing of all of your website directories including sub-dir

how to refresh Select2 dropdown menu after ajax loading different content?

It's common for other components to be listening to the change event, or for custom event handlers to be attached that may have side effects. Select2 does not have a custom event (like select2:update) that can be triggered other than change. You can rely on jQuery's event namespacing to limit the scope to Select2 though by triggering the *change.select2 event.

$('#state').trigger('change.select2'); // Notify only Select2 of changes

Correct way to use get_or_create?

get_or_create() returns a tuple:

customer.source, created  = Source.objects.get_or_create(name="Website")
  • created ? has a boolean value, is created or not.

  • customer.source ? has an object of get_or_create() method.

Edit a specific Line of a Text File in C#

When you create a StreamWriter it always create a file from scratch, you will have to create a third file and copy from target and replace what you need, and then replace the old one. But as I can see what you need is XML manipulation, you might want to use XmlDocument and modify your file using Xpath.

Understanding REST: Verbs, error codes, and authentication

For the examples you stated I'd use the following:


POST /users/1/activation


DELETE /users/1/activation


PUT /passwords (this assumes the user is authenticated)


POST /credits (this assumes the user is authenticated)

For errors you'd return the error in the body in the format that you got the request in, so if you receive:

DELETE /users/1.xml

You'd send the response back in XML, the same would be true for JSON etc...

For authentication you should use http authentication.

Visual Studio Error: (407: Proxy Authentication Required)

After three days of searching, the solution fell into my lap.

Now, what happened was VS tried to do an automatic update but was stopped by the proxy. I was prompted for credentials and the check took place.

I was inspired to check the TFS server connection just for kicks in case that prompt would possibly establish a connection for the TFS server to tunnel through... lo and behold! It worked!


  1. Open TOOLS>Extensions & Updates
  2. Click on Updates... in the left-hand menu
  3. There will be a failure notice on screen and a link to enter your credentials. Click it and enter them.
  4. Close the Extension manager.
  5. Click TEAM>Connect to TFS server...
  6. Enter the address and it will work!

Note: Some have suggested trying to use the proxy credential prompt by opening the integrated browser but this has not worked. I am not an expert but I think they are connecting through different channels within windows itself.

There is no editing of devenv.exe.config required for this to work.

It will be a pain to have to check for updates manually every time you need to connect to the server, but this is the best solution I have come up with until Microsoft fixes this issue permanently with an update or future release.

Locking a file in Python

The scenario is like that: The user requests a file to do something. Then, if the user sends the same request again, it informs the user that the second request is not done until the first request finishes. That's why, I use lock-mechanism to handle this issue.

Here is my working code:

from lockfile import LockFile
lock = LockFile(lock_file_path)
status = ""
if not lock.is_locked():
    status = lock.path + ' is locked.'
    print status
    status = lock.path + " is already locked."
    print status

return status

What is "X-Content-Type-Options=nosniff"?

The X-Content-Type-Options response HTTP header is a marker used by the server to indicate that the MIME types advertised in the Content-Type headers should not be changed and be followed. This allows to opt-out of MIME type sniffing, or, in other words, it is a way to say that the webmasters knew what they were doing.

Syntax :

X-Content-Type-Options: nosniff

Directives :

nosniff Blocks a request if the requested type is 1. "style" and the MIME type is not "text/css", or 2. "script" and the MIME type is not a JavaScript MIME type.

Note: nosniff only applies to "script" and "style" types. Also applying nosniff to images turned out to be incompatible with existing web sites.

Specification :

Adding default parameter value with type hint in Python

Your second way is correct.

def foo(opts: dict = {}):


this outputs

{'opts': <class 'dict'>}

It's true that's it's not listed in PEP 484, but type hints are an application of function annotations, which are documented in PEP 3107. The syntax section makes it clear that keyword arguments works with function annotations in this way.

I strongly advise against using mutable keyword arguments. More information here.

How to set a single, main title above all the subplots with Pyplot?

A few points I find useful when applying this to my own plots:

  • I prefer the consistency of using fig.suptitle(title) rather than plt.suptitle(title)
  • When using fig.tight_layout() the title must be shifted with fig.subplots_adjust(top=0.88)
  • See answer below about fontsizes

Example code taken from subplots demo in matplotlib docs and adjusted with a master title.

A nice 4x4 plot

import matplotlib.pyplot as plt
import numpy as np

# Simple data to display in various forms
x = np.linspace(0, 2 * np.pi, 400)
y = np.sin(x ** 2)

fig, axarr = plt.subplots(2, 2)
fig.suptitle("This Main Title is Nicely Formatted", fontsize=16)

axarr[0, 0].plot(x, y)
axarr[0, 0].set_title('Axis [0,0] Subtitle')
axarr[0, 1].scatter(x, y)
axarr[0, 1].set_title('Axis [0,1] Subtitle')
axarr[1, 0].plot(x, y ** 2)
axarr[1, 0].set_title('Axis [1,0] Subtitle')
axarr[1, 1].scatter(x, y ** 2)
axarr[1, 1].set_title('Axis [1,1] Subtitle')

# # Fine-tune figure; hide x ticks for top plots and y ticks for right plots
plt.setp([a.get_xticklabels() for a in axarr[0, :]], visible=False)
plt.setp([a.get_yticklabels() for a in axarr[:, 1]], visible=False)

# Tight layout often produces nice results
# but requires the title to be spaced accordingly

performing HTTP requests with cURL (using PROXY)

From man curl:

-x, --proxy <[protocol://][user:password@]proxyhost[:port]>

     Use the specified HTTP proxy. 
     If the port number is not specified, it is assumed at port 1080.

General way:

export http_proxy=http://your.proxy.server:port/

Then you can connect through proxy from (many) application.

And, as per comment below, for https:

export https_proxy=https://your.proxy.server:port/

Rename a table in MySQL

Please try

RENAME TABLE  `oldTableName` TO  `newTableName`

Cannot use object of type stdClass as array?

Have same problem today, solved like this:

If you call json_decode($somestring) you will get an Object and you need to access like $object->key , but if u call json_decode($somestring, true) you will get an dictionary and can access like $array['key']

How to remove unused C/C++ symbols with GCC and ld?

I don't know if this will help with your current predicament as this is a recent feature, but you can specify the visibility of symbols in a global manner. Passing -fvisibility=hidden -fvisibility-inlines-hidden at compilation can help the linker to later get rid of unneeded symbols. If you're producing an executable (as opposed to a shared library) there's nothing more to do.

More information (and a fine-grained approach for e.g. libraries) is available on the GCC wiki.

Convert integers to strings to create output filenames at run time

Here is my subroutine approach to this problem. it transforms an integer in the range 0 : 9999 as a character. For example, the INTEGER 123 is transformed into the character 0123. hope it helps.

P.S. - sorry for the comments; they make sense in Romanian :P

 subroutine nume_fisier (i,filename_tot)

   implicit none
   integer :: i

   integer :: integer_zeci,rest_zeci,integer_sute,rest_sute,integer_mii,rest_mii
   character(1) :: filename1,filename2,filename3,filename4
   character(4) :: filename_tot

! Subrutina ce transforma un INTEGER de la 0 la 9999 in o serie de CARACTERE cu acelasi numar

! pentru a fi folosite in numerotarea si denumirea fisierelor de rezultate.

 if(i<=9) then


 elseif(i>=10.and.i<=99) then


 elseif(i>=100.and.i<=999) then


 elseif(i>=1000.and.i<=9999) then



 end subroutine nume_fisier

Checking whether the pip is installed?

$ which pip


 $ pip -V 

execute this command into your terminal. It should display the location of executable file eg. /usr/local/bin/pip and the second command will display the version if the pip is installed correctly.

Efficient way to do batch INSERTS with JDBC

The Statement gives you the following option:

Statement stmt = con.createStatement();

stmt.addBatch("INSERT INTO employees VALUES (1000, 'Joe Jones')");
stmt.addBatch("INSERT INTO departments VALUES (260, 'Shoe')");
stmt.addBatch("INSERT INTO emp_dept VALUES (1000, 260)");

// submit a batch of update commands for execution
int[] updateCounts = stmt.executeBatch();

How do I capture SIGINT in Python?

Yet Another Snippet

Referred main as the main function and exit_gracefully as the CTRL + c handler

if __name__ == '__main__':
    except KeyboardInterrupt:

How to select only 1 row from oracle sql?

"FirstRow" Is a restriction and therefor it's place in the where clause not in the select clause. And it's called rownum

select * from dual where rownum = 1;

How to Create a circular progressbar in Android which rotates on it?





for second sahpe with id="@android:id/progress

hope it works

Align text in a table header

For me none of the above worked. I think it is because I have two levels of header and a fixed width on level 1. So I couldn't align the text inside the corresponding columns on level 2.

|           lvl 1           |
| lvl 2 col a | lvl 2 col b |

I had to use the combination of width:auto and text:align-center :

<th style="width:auto;text-align:center">lvl 2 col a</th>
<th style="width:auto;text-align:center">lvl 2 col b</th>

FileNotFoundException..Classpath resource not found in spring?

Best way to handle such error-"Use Annotation". spring.xml-<context:component-scan base-package=com.SpringCollection.SpringCollection"/>

add annotation in that class for which you want to use Bean ID(i am using class "First")-


public class First {

Changes In Main Class**-

ApplicationContext context = new AnnotationConfigApplicationContext(First.class); use this.

Check an integer value is Null in c#

Nullable<T> (or ?) exposes a HasValue flag to denote if a value is set or the item is null.

Also, nullable types support ==:

if (Age == null)

The ?? is the null coalescing operator and doesn't result in a boolean expression, but a value returned:

int i = Age ?? 0;

So for your example:

if (age == null || age == 0)


if (age.GetValueOrDefault(0) == 0)


if ((age ?? 0) == 0)

Or ternary:

int i = age.HasValue ? age.Value : 0;

How do you round to 1 decimal place in Javascript?

I made one that returns number type and also places decimals only if are needed (no 0 padding).


roundWithMaxPrecision(11.234, 2); //11.23
roundWithMaxPrecision(11.234, 1); //11.2
roundWithMaxPrecision(11.234, 4); //11.23
roundWithMaxPrecision(11.234, -1); //10

roundWithMaxPrecision(4.2, 2); //4.2
roundWithMaxPrecision(4.88, 1); //4.9

The code:

function roundWithMaxPrecision (n, precision) {
    let precisionWithPow10 = Math.pow(10, precision);
    return Math.round(n * precisionWithPow10) / precisionWithPow10;

Parsing arguments to a Java command line program

Use the Apache Commons CLI library commandline.getArgs() to get arg1, arg2, arg3, and arg4. Here is some code:

    import org.apache.commons.cli.CommandLine;
    import org.apache.commons.cli.Option;
    import org.apache.commons.cli.Options;
    import org.apache.commons.cli.Option.Builder;
    import org.apache.commons.cli.CommandLineParser;
    import org.apache.commons.cli.DefaultParser;
    import org.apache.commons.cli.ParseException;

    public static void main(String[] parameters)
        CommandLine commandLine;
        Option option_A = Option.builder("A")
            .desc("The A option")
        Option option_r = Option.builder("r")
            .desc("The r option")
        Option option_S = Option.builder("S")
            .desc("The S option")
        Option option_test = Option.builder()
            .desc("The test option")
        Options options = new Options();
        CommandLineParser parser = new DefaultParser();

        String[] testArgs =
        { "-r", "opt1", "-S", "opt2", "arg1", "arg2",
          "arg3", "arg4", "--test", "-A", "opt3", };


            commandLine = parser.parse(options, testArgs);

            if (commandLine.hasOption("A"))
                System.out.print("Option A is present.  The value is: ");

            if (commandLine.hasOption("r"))
                System.out.print("Option r is present.  The value is: ");

            if (commandLine.hasOption("S"))
                System.out.print("Option S is present.  The value is: ");

            if (commandLine.hasOption("test"))
                System.out.println("Option test is present.  This is a flag option.");

                String[] remainder = commandLine.getArgs();
                System.out.print("Remaining arguments: ");
                for (String argument : remainder)
                    System.out.print(" ");


        catch (ParseException exception)
            System.out.print("Parse error: ");

List an Array of Strings in alphabetical order

Arrays.sort(stringArray); This sorts the string array based on the Unicode characters values. All strings that contain uppercase characters at the beginning of the string will be at the top of the sorted list alphabetically followed by all strings with lowercase characters. Hence if the array contains strings beginning with both uppercase characters and lowercase characters, the sorted array would not return a case insensitive order alphabetical list

String[] strArray = { "Carol", "bob", "Alice" };

Output is : Alice, Carol, bob,

If you require the Strings to be sorted without regards to case, you'll need a second argument, a Comparator, for Arrays.sort(). Such a comparator has already been written for us and can be accessed as a static on the String class named CASE_INSENSITIVE_ORDER.

String[] strArray = { "Carol", "bob", "Alice" };
Arrays.sort(stringArray, String.CASE_INSENSITIVE_ORDER);
System.out.println(Arrays.toString(strArray ));

Output is : Alice, bob, Carol

Class is not abstract and does not override abstract method

Both classes Rectangle and Ellipse need to override both of the abstract methods.

To work around this, you have 3 options:

  • Add the two methods
  • Make each class that extends Shape abstract
  • Have a single method that does the function of the classes that will extend Shape, and override that method in Rectangle and Ellipse, for example:

    abstract class Shape {
        // ...
        void draw(Graphics g);


    class Rectangle extends Shape {
        void draw(Graphics g) {
            // ...


    class Ellipse extends Shape {
        void draw(Graphics g) {
            // ...

And you can switch in between them, like so:

    Shape shape = new Ellipse();
    shape.draw(/* ... */);

    shape = new Rectangle();
    shape.draw(/* ... */);

Again, just an example.