Programs & Examples On #Mysql escape string

insert password into database in md5 format?

if you want to use md5 encryptioon you can do it in your php script

$pass = $_GET['pass'];

$newPass = md5($pass)

and then insert it into the database that way, however MD5 is a one way encryption method and is near on impossible to decrypt without difficulty

How to add a custom Ribbon tab using VBA?

I struggled like mad, but this is actually the right answer. For what it is worth, what I missed was is this:

  1. As others say, one can't create the CustomUI ribbon with VBA, however, you don't need to!
  2. The idea is you create your xml Ribbon code using Excel's File > Options > Customize Ribbon, and then export the Ribbon to a .customUI file (it's just a txt file, with xml in it)
  3. Now comes the trick: you can include the .customUI code in your .xlsm file using the MS tool they refer to here, by copying the code from the .customUI file
  4. Once it is included in the .xlsm file, every time you open it, the ribbon you defined is added to the user's ribbon - but do use < ribbon startFromScratch="false" > or you lose the rest of the ribbon. On exit-ing the workbook, the ribbon is removed.
  5. From here on it is simple, create your ribbon, copy the xml code that is specific to your ribbon from the .customUI file, and place it in a wrapper as shown above (...< tabs> your xml < /tabs...)

By the way the page that explains it on Ron's site is now at

And here is his example on how you enable /disable buttons on the Ribbon

For other xml examples of ribbons please also see

How to get all key in JSON object (javascript)

ES6 of the day here;

const json_getAllKeys = data => (
  data.reduce((keys, obj) => (
    keys.concat(Object.keys(obj).filter(key => (
      keys.indexOf(key) === -1))
  ), [])

And yes it can be written in very long one line;

const json_getAllKeys = data => data.reduce((keys, obj) => keys.concat(Object.keys(obj).filter(key => keys.indexOf(key) === -1)), [])

EDIT: Returns all first order keys if the input is of type array of objects

Add items to comboBox in WPF

There are many ways to perform this task. Here is a simple one:

<Window x:Class="WPF_Demo1.MainWindow"
    Title="MainWindow" Height="500" Width="773">

<DockPanel LastChildFill="False">
    <StackPanel DockPanel.Dock="Top" Background="Red" Margin="2">
        <StackPanel Orientation="Horizontal" x:Name="spTopNav">
            <ComboBox x:Name="cboBox1" MinWidth="120"> <!-- Notice we have used x:Name to identify the object that we want to operate upon.-->
                <ComboBoxItem Content="X"/>
                <ComboBoxItem Content="Y"/>
                <ComboBoxItem Content="Z"/>
    <StackPanel DockPanel.Dock="Bottom" Background="Orange" Margin="2">
        <StackPanel Orientation="Horizontal" x:Name="spBottomNav">
        <TextBlock Height="30" Foreground="White">Left Docked StackPanel 2</TextBlock>
    <StackPanel MinWidth="200" DockPanel.Dock="Left" Background="Teal" Margin="2" x:Name="StackPanelLeft">
        <TextBlock  Foreground="White">Bottom Docked StackPanel Left</TextBlock>

    <StackPanel DockPanel.Dock="Right" Background="Yellow" MinWidth="150" Margin="2" x:Name="StackPanelRight"></StackPanel>
    <Button Content="Button" Height="410" VerticalAlignment="Top" Width="75" x:Name="myButton" Click="myButton_Click"/>



Next, we have the C# code:

    private void myButton_Click(object sender, RoutedEventArgs e)
        ComboBoxItem cboBoxItem = new ComboBoxItem(); // Create example instance of our desired type.
        Type type1 = cboBoxItem.GetType();
        object cboBoxItemInstance = Activator.CreateInstance(type1); // Construct an instance of that type.
        for (int i = 0; i < 12; i++)
            string newName = "stringExample" + i.ToString();
           // Generate the objects from our list of strings.
            ComboBoxItem item = this.CreateComboBoxItem((ComboBoxItem)cboBoxItemInstance, "nameExample_" + newName, newName);
            cboBox1.Items.Add(item); // Add each newly constructed item to our NAMED combobox.
    private ComboBoxItem CreateComboBoxItem(ComboBoxItem myCbo, string content, string name)
        Type type1 = myCbo.GetType();
        ComboBoxItem instance = (ComboBoxItem)Activator.CreateInstance(type1);
        // Here, we're using reflection to get and set the properties of the type.
        PropertyInfo Content = instance.GetType().GetProperty("Content", BindingFlags.Public | BindingFlags.Instance);
        PropertyInfo Name = instance.GetType().GetProperty("Name", BindingFlags.Public | BindingFlags.Instance);
        this.SetProperty<ComboBoxItem, String>(Content, instance, content);
        this.SetProperty<ComboBoxItem, String>(Name, instance, name);

        return instance;
        //PropertyInfo prop = type.GetProperties(rb1);

Note: This is using reflection. If you'd like to learn more about the basics of reflection and why you might want to use it, this is a great introductory article:

If you'd like to learn more about how you might use reflection with WPF specifically, here are some resources:

And if you want to massively speed up the performance of reflection, it's best to use IL to do that, like this:

Inline JavaScript onclick function

Based on the answer that @Mukund Kumar gave here's a version that passes the event argument to the anonymous function:

<a href="#" onClick="(function(e){
    alert('Hey i am calling');
    return false;
})(arguments[0]);return false;">click here</a>

How to multiply all integers inside list

Try a list comprehension:

l = [x * 2 for x in l]

This goes through l, multiplying each element by two.

Of course, there's more than one way to do it. If you're into lambda functions and map, you can even do

l = map(lambda x: x * 2, l)

to apply the function lambda x: x * 2 to each element in l. This is equivalent to:

def timesTwo(x):
    return x * 2

l = map(timesTwo, l)

Note that map() returns a map object, not a list, so if you really need a list afterwards you can use the list() function afterwards, for instance:

l = list(map(timesTwo, l))

Thanks to Minyc510 in the comments for this clarification.

How can I check if a MySQL table exists with PHP?

You can use many different queries to check if a table exists. Below is a comparison between several:

mysql_query('select 1 from `table_name` group by 1'); or  
mysql_query('select count(*) from `table_name`');

mysql_query("DESCRIBE `table_name`");  
70000   rows: 24ms  
1000000 rows: 24ms  
5000000 rows: 24ms

mysql_query('select 1 from `table_name`');  
70000   rows: 19ms  
1000000 rows: 23ms  
5000000 rows: 29ms

mysql_query('select 1 from `table_name` group by 1'); or  
mysql_query('select count(*) from `table_name`');  
70000   rows: 18ms  
1000000 rows: 18ms  
5000000 rows: 18ms  

These benchmarks are only averages:

Static variables in C++

Excuse me when I answer your questions out-of-order, it makes it easier to understand this way.

When static variable is declared in a header file is its scope limited to .h file or across all units.

There is no such thing as a "header file scope". The header file gets included into source files. The translation unit is the source file including the text from the header files. Whatever you write in a header file gets copied into each including source file.

As such, a static variable declared in a header file is like a static variable in each individual source file.

Since declaring a variable static this way means internal linkage, every translation unit #includeing your header file gets its own, individual variable (which is not visible outside your translation unit). This is usually not what you want.

I would like to know what is the difference between static variables in a header file vs declared in a class.

In a class declaration, static means that all instances of the class share this member variable; i.e., you might have hundreds of objects of this type, but whenever one of these objects refers to the static (or "class") variable, it's the same value for all objects. You could think of it as a "class global".

Also generally static variable is initialized in .cpp file when declared in a class right ?

Yes, one (and only one) translation unit must initialize the class variable.

So that does mean static variable scope is limited to 2 compilation units ?

As I said:

  • A header is not a compilation unit,
  • static means completely different things depending on context.

Global static limits scope to the translation unit. Class static means global to all instances.

I hope this helps.

PS: Check the last paragraph of Chubsdad's answer, about how you shouldn't use static in C++ for indicating internal linkage, but anonymous namespaces. (Because he's right. ;-) )

How does Java handle integer underflows and overflows and how would you check for it?

If it overflows, it goes back to the minimum value and continues from there. If it underflows, it goes back to the maximum value and continues from there.

You can check that beforehand as follows:

public static boolean willAdditionOverflow(int left, int right) {
    if (right < 0 && right != Integer.MIN_VALUE) {
        return willSubtractionOverflow(left, -right);
    } else {
        return (~(left ^ right) & (left ^ (left + right))) < 0;

public static boolean willSubtractionOverflow(int left, int right) {
    if (right < 0) {
        return willAdditionOverflow(left, -right);
    } else {
        return ((left ^ right) & (left ^ (left - right))) < 0;

(you can substitute int by long to perform the same checks for long)

If you think that this may occur more than often, then consider using a datatype or object which can store larger values, e.g. long or maybe java.math.BigInteger. The last one doesn't overflow, practically, the available JVM memory is the limit.

If you happen to be on Java8 already, then you can make use of the new Math#addExact() and Math#subtractExact() methods which will throw an ArithmeticException on overflow.

public static boolean willAdditionOverflow(int left, int right) {
    try {
        Math.addExact(left, right);
        return false;
    } catch (ArithmeticException e) {
        return true;

public static boolean willSubtractionOverflow(int left, int right) {
    try {
        Math.subtractExact(left, right);
        return false;
    } catch (ArithmeticException e) {
        return true;

The source code can be found here and here respectively.

Of course, you could also just use them right away instead of hiding them in a boolean utility method.

Sort objects in an array alphabetically on one property of the array

To support unicode:

objArray.sort(function(a, b) {
   return a.DepartmentName.localeCompare(b.DepartmentName);

How to put a tooltip on a user-defined function

A lot of dancing around the answer. You can add the UDF context help, but you have to export the Module and edit the contents in a text editor, then re-import it to VBA. Here's the example from Chip Pearson: Adding Code Attributes

What is the maximum length of a valid email address?

To help the confused rookies like me, the answer to "What is the maximum length of a valid email address?" is 254 characters.

If your application uses an email, just set your field to accept 254 characters or less and you are good to go.

You can run a bunch of tests on an email to see if it is valid here.

The RFC, or Request for Comments is a type of publication from the Internet Engineering Task Force (IETF) that defines 254 characters as the limit. Located here -

Getting String Value from Json Object Android

Here is the solution I used for me Is works for fetching JSON from string

protected String getJSONFromString(String stringJSONArray) throws JSONException {
        return new StringBuffer(
               new JSONArray(stringJSONArray).getJSONObject(0).getString("cartype"))
                   .append(" ")
               new JSONArray(employeeID).getJSONObject(0).getString("model"))

How can I read the contents of an URL with Python?

from urllib.request import urlopen

# if has Chinese, apply decode()
html = urlopen("").read().decode('utf-8')

Alternative to a goto statement in Java

Try the code below. It works for me.

for (int iTaksa = 1; iTaksa <=8; iTaksa++) { // 'Count 8 Loop is  8 Taksa

    strTaksaStringStar[iCountTaksa] = strTaksaStringCount[iTaksa];

    LabelEndTaksa_Exit : {
        if (iCountTaksa == 1) { //If count is 6 then next it's 2
            iCountTaksa = 2;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 2) { //If count is 2 then next it's 3
            iCountTaksa = 3;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 3) { //If count is 3 then next it's 4
            iCountTaksa = 4;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 4) { //If count is 4 then next it's 7
            iCountTaksa = 7;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 7) { //If count is 7 then next it's 5
            iCountTaksa = 5;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 5) { //If count is 5 then next it's 8
            iCountTaksa = 8;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 8) { //If count is 8 then next it's 6
            iCountTaksa = 6;
            break  LabelEndTaksa_Exit;

        if (iCountTaksa == 6) { //If count is 6 then loop 1  as 1 2 3 4 7 5 8 6  --> 1
            iCountTaksa = 1;
            break  LabelEndTaksa_Exit;
    }   //LabelEndTaksa_Exit : {

} // "for (int iTaksa = 1; iTaksa <=8; iTaksa++) {"

AcquireConnection method call to the connection manager <Excel Connection Manager> failed with error code 0xC0202009

In order to resolve this issue make all your data flow tasks in one sequence. It means it should not execute parallel. One data flow task sequence should contain only one data flow task and for this another data flow task as sequence.


enter image description here

Update Row if it Exists Else Insert Logic with Entity Framework


public static void InsertOrUpdateRange<T, T2>(this T entity, List<T2> updateEntity) 
        where T : class
        where T2 : class
            foreach(var e in updateEntity)

        public static void InsertOrUpdate<T, T2>(this T entity, T2 updateEntity) 
        where T : class
        where T2 : class
            if (context.Entry(updateEntity).State == EntityState.Detached)
                if (context.Set<T2>().Any(t => t == updateEntity))


Simple InputBox function

Probably the simplest way is to use the InputBox method of the Microsoft.VisualBasic.Interaction class:


$title = 'Demographics'
$msg   = 'Enter your demographics:'

$text = [Microsoft.VisualBasic.Interaction]::InputBox($msg, $title)

How do I fix twitter-bootstrap on IE?

Need to include these two scripts for IE

<script src=""></script>
<script src=""></script>

change html text from link with jquery

try this in javascript

 document.getElementById("22IdMObileFull").text ="itsClicked"

IE throws JavaScript Error: The value of the property 'googleMapsQuery' is null or undefined, not a Function object (works in other browsers)

I found the answer, and in spite of what I reported, it was NOT browser specific. The bug was in my function code, and would have occurred in any browser. It boils down to this. I had two lines in my code that were FireFox/FireBug specific. They used console.log. In IE, they threw an error, so I commented them out (or so I thought). I did a crappy job commenting them out, and broke the bracketing in my function.

Original Code (with console.log in it):

if (sxti.length <= 50) console.log('sxti=' + sxti);
if (sxph.length <= 50) console.log('sxph=' + sxph);

Broken Code (misplaced brackets inside comments):

if (sxti.length <= 50) { //console.log('sxti=' + sxti); }
if (sxph.length <= 50) { //console.log('sxph=' + sxph); }

Fixed Code (fixed brackets outside comments):

if (sxti.length <= 50) { }//console.log('sxti=' + sxti);
if (sxph.length <= 50) { }//console.log('sxph=' + sxph);

So, it was my own sloppy coding. The function really wasn't defined, because a syntax error kept it from being closed.

Oh well, live and learn. ;)

Why are empty catch blocks a bad idea?

I wouldn't stretch things as far as to say that who uses empty catch blocks is a bad programmer and doesn't know what he is doing...

I use empty catch blocks if necessary. Sometimes programmer of library I'm consuming doesn't know what he is doing and throws exceptions even in situations when nobody needs it.

For example, consider some http server library, I couldn't care less if server throws exception because client has disconnected and index.html couldn't be sent.

Disable all table constraints in Oracle

with cursor for loop (user = 'TRANEE', table = 'D')

    constr all_constraints.constraint_name%TYPE;
    for constr in
        (select constraint_name from all_constraints
        where table_name = 'D'
        and owner = 'TRANEE')
        execute immediate 'alter table D disable constraint '||constr.constraint_name;
    end loop;

(If you change disable to enable, you can make all constraints enable)

Display a float with two decimal places in Python

If you want to get a floating point value with two decimal places limited at the time of calling input,

Check this out ~

a = eval(format(float(input()), '.2f'))   # if u feed 3.1415 for 'a'.
print(a)                                  # output 3.14 will be printed.

Determine the line of code that causes a segmentation fault?

Also, you can give valgrind a try: if you install valgrind and run

valgrind --leak-check=full <program>

then it will run your program and display stack traces for any segfaults, as well as any invalid memory reads or writes and memory leaks. It's really quite useful.

How to check size of a file using Bash?

I would use du's --threshold for this. Not sure if this option is available in all versions of du but it is implemented in GNU's version.

Quoting from du(1)'s manual:

-t, --threshold=SIZE
       exclude entries smaller than SIZE if positive, or entries greater
       than SIZE if negative

Here's my solution, using du --threshold= for OP's use case:

if [[ -z "$(du --threshold=${THRESHOLD} file.txt)" ]]; then
    mail -s "file.txt size is below ${THRESHOLD}, please fix. " [email protected] < /dev/null
    mv -f /root/tmp/file.txt /var/www/file.txt

The advantage of that, is that du can accept an argument to that option in a known format - either human as in 10K, 10MiB or what ever you feel comfortable with - you don't need to manually convert between formats / units since du handles that.

For reference, here's the explanation on this SIZE argument from the man page:

The SIZE argument is an integer and optional unit (example: 10K is 
10*1024). Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers
of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on.

Setting UILabel text to bold

Use attributed string:

// Define attributes
let labelFont = UIFont(name: "HelveticaNeue-Bold", size: 18)
let attributes :Dictionary = [NSFontAttributeName : labelFont]

// Create attributed string
var attrString = NSAttributedString(string: "Foo", attributes:attributes)
label.attributedText = attrString

You need to define attributes.

Using attributed string you can mix colors, sizes, fonts etc within one text

Send value of submit button when form gets posted

To start, using the same ID twice is not a good idea. ID's should be unique, if you need to style elements you should use a class to apply CSS instead.

At last, you defined the name of your submit button as Tea and Coffee, but in your PHP you are using submit as index. your index should have been $_POST['Tea'] for example. that would require you to check for it being set as it only sends one , you can do that with isset().

Buy anyway , user4035 just beat me to it , his code will "fix" this for you.

How to restart a node.js server

I had the same problem and then wrote this shell script which kills all of the existing node processes:

echo "The following node processes were found:"
ps aux | grep " node " | grep -v grep
nodepids=$(ps aux | grep " node " | grep -v grep | cut -c10-15)

echo "OK, so we will stop these process/es now..."

for nodepid in ${nodepids[@]}
echo "Stopping PID :"$nodepid
kill -9 $nodepid
echo "Done"

After this is saved as a shell script ( file you might want to add it to your PATH as described here.

(Please note that this will kill all of the processes with " node " in it's name except grep's own, so I guess in some cases it may also kill some other processes with a similar name)

Adjust plot title (main) position

To summarize and explain visually how it works. Code construction is as follows:

par(mar = c(3,2,2,1))
barplot(...all parameters...)
title("Title text", adj = 0.5, line = 0)


par(mar = c(low, left, top, right)) - margins of the graph area.

title("text" - title text
      adj  = from left (0) to right (1) with anything in between: 0.1, 0.2, etc...
      line = positive values move title text up, negative - down)

enter image description here

Why does instanceof return false for some literals?

 typeof(text) === 'string' || text instanceof String; 

you can use this, it will work for both case as

  1. var text="foo"; // typeof will work

  2. String text= new String("foo"); // instanceof will work

php - push array into array - key issue

Don't use array_values on your $row

$res_arr_values = array();
while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
       array_push($res_arr_values, $row);

Also, the preferred way to add a value to an array is writing $array[] = $value;, not using array_push

$res_arr_values = array();
while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
       $res_arr_values[] = $row;

And a further optimization is not to call mysql_fetch_array($result, MYSQL_ASSOC) but to use mysql_fetch_assoc($result) directly.

$res_arr_values = array();
while ($row = mysql_fetch_assoc($result))
       $res_arr_values[] = $row;

Accessing Redux state in an action creator?

I agree with @Bloomca. Passing the value needed from the store into the dispatch function as an argument seems simpler than exporting the store. I made an example here:

import React from "react";
import {connect} from "react-redux";
import * as actions from '../actions';

class App extends React.Component {

    const data =;

    return (
      <div onClick={ this.handleClick.bind(this)}>Click Me!</div>      

const mapStateToProps = (state) => {
  return { someStateObject: state.someStateObject };

const mapDispatchToProps = (dispatch) => {
  return {
    someDispatchFunction:(data) => { dispatch(actions.someDispatchFunction(data))},


export default connect(mapStateToProps, mapDispatchToProps)(App);

How to post data in PHP using file_get_contents?

An alternative, you can also use fopen

$params = array('http' => array(
    'method' => 'POST',
    'content' => 'toto=1&tata=2'

$ctx = stream_context_create($params);
$fp = @fopen($sUrl, 'rb', false, $ctx);
if (!$fp)
    throw new Exception("Problem with $sUrl, $php_errormsg");

$response = @stream_get_contents($fp);
if ($response === false) 
    throw new Exception("Problem reading data from $sUrl, $php_errormsg");

How do I connect to a Websphere Datasource with a given JNDI name?

Find below code to get database connection from your web app server. Just create datasource in app server and use following code to get connection :

// To Get DataSource
Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup("jdbc/abcd");
// Get Connection and Statement
Connection c = ds.getConnection();
stmt = c.createStatement();

Import naming and sql classes. No need to add any xml file or to edit anything in project.
That's it..

python requests get cookies

If you need the path and thedomain for each cookie, which get_dict() is not exposes, you can parse the cookies manually, for instance:

    {'name':, 'value': c.value, 'domain': c.domain, 'path': c.path}
    for c in session.cookies

How to create a property for a List<T>

public class MyClass<T>
  private List<T> list;

  public List<T> MyList { get { return list; } set { list = value; } }

Then you can do something like

MyClass<int> instance1 = new MyClass<int>();
List<int> integers = instance1.MyList;

MyClass<Person> instance2 = new MyClass<Person>();
IEnumerable<Person> persons = instance2.MyList;

CSS position absolute full width problem

You need to add position:relative to #wrap element.

When you add this, all child elements will be positioned in this element, not browser window.

WebSocket connection failed: Error during WebSocket handshake: Unexpected response code: 400

The currently accepted solution is misleading.

According to the official documentation, adding the transports: [ 'websocket' ] option effectively removes the ability to fallback to long-polling when the websocket connection cannot be established. This option is what makes so robust in the first place because it can adapt to many scenarios.

In that particular case where one wishes to solely rely on websockets, directly using the WebSocket API is recommended.

For other cases (supposedly most users), this is most likely a reverse proxy/server configuration problem.

The official documentation suggests the following depending on your environment:

NginX configuration

http {
  server {
    listen 3000;

    location / {
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $host;

      proxy_pass http://nodes;

      # enable WebSockets
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";

  upstream nodes {
    # enable sticky session based on IP

    server app01:3000;
    server app02:3000;
    server app03:3000;

Apache HTTPD configuration

Header add Set-Cookie "SERVERID=sticky.%{BALANCER_WORKER_ROUTE}e; path=/" env=BALANCER_ROUTE_CHANGED

<Proxy "balancer://nodes_polling">
    BalancerMember "http://app01:3000" route=app01
    BalancerMember "http://app02:3000" route=app02
    BalancerMember "http://app03:3000" route=app03
    ProxySet stickysession=SERVERID

<Proxy "balancer://nodes_ws">
    BalancerMember "ws://app01:3000" route=app01
    BalancerMember "ws://app02:3000" route=app02
    BalancerMember "ws://app03:3000" route=app03
    ProxySet stickysession=SERVERID

RewriteEngine On
RewriteCond %{HTTP:Upgrade} =websocket [NC]
RewriteRule /(.*) balancer://nodes_ws/$1 [P,L]
RewriteCond %{HTTP:Upgrade} !=websocket [NC]
RewriteRule /(.*) balancer://nodes_polling/$1 [P,L]

ProxyTimeout 3

HAProxy configuration

listen chat
  bind *:80
  default_backend nodes

backend nodes
  option httpchk HEAD /health
  http-check expect status 200
  cookie io prefix indirect nocache # using the `io` cookie set upon handshake
  server app01 app01:3000 check cookie app01
  server app02 app02:3000 check cookie app02
  server app03 app03:3000 check cookie app03

Also worth reading this on upgrading connections in HAProxy.

For more details please refer to the official documentation link above.


Varnish (source here)

sub vcl_recv {
    if (req.http.upgrade ~ "(?i)websocket") {
        return (pipe);

sub vcl_pipe {
    if (req.http.upgrade) {
        set bereq.http.upgrade = req.http.upgrade;
        set bereq.http.connection = req.http.connection;

How do I write good/correct package files

__all__ is very good - it helps guide import statements without automatically importing modules

using __all__ and import * is redundant, only __all__ is needed

I think one of the most powerful reasons to use import * in an to import packages is to be able to refactor a script that has grown into multiple scripts without breaking an existing application. But if you're designing a package from the start. I think it's best to leave files empty.

for example: - contains classes related to foo such as fooFactory, tallFoo, shortFoo

then the app grows and now it's a whole folder


then the init script can say

__all__ = ['foofactories', 'tallFoos', 'shortfoos', 'medumfoos',
           'santaslittlehelperfoo', 'superawsomefoo', 'anotherfoo']
# deprecated to keep older scripts who import this from breaking
from foo.foofactories import fooFactory
from foo.tallfoos import tallFoo
from foo.shortfoos import shortFoo

so that a script written to do the following does not break during the change:

from foo import fooFactory, tallFoo, shortFoo

Insert data into table with result from another select query

INSERT INTO `test`.`product` ( `p1`, `p2`, `p3`) 
SELECT sum(p1), sum(p2), sum(p3) 
FROM `test`.`product`;

sendUserActionEvent() is null

This has to do with having two buttons with the same ID in two different Activities, sometimes Android Studio can't find, You just have to give your button a new ID and re Build the Project

Converting JSON to XML in Java

If you have a valid dtd file for the xml then you can easily transform json to xml and xml to json using the eclipselink jar binary.

Refer this:

The article also has a sample project (including the supporting third party jars) as a zip file which can be downloaded for reference purpose.

What is the maximum float in Python?

For all practical purposes, and with no import at all, one can use:

x = float("inf")

More detail on this related question: How can I represent an infinite number in Python?

How do I remove all non alphanumeric characters from a string except dash?

Using System.Linq

string withOutSpecialCharacters = new string(stringWithSpecialCharacters.Where(c =>char.IsLetterOrDigit(c) || char.IsWhiteSpace(c) || c == '-').ToArray());

Get final URL after curl is redirected

Thanks, that helped me. I made some improvements and wrapped that in a helper script "finalurl":

curl $1 -s -L -I -o /dev/null -w '%{url_effective}'
  • -o output to /dev/null
  • -I don't actually download, just discover the final URL
  • -s silent mode, no progressbars

This made it possible to call the command from other scripts like this:

echo `finalurl http://someurl/`

CSS no text wrap

Additionally to overflow:hidden, use


How to add parameters to HttpURLConnection using POST using NameValuePair

The accepted answer throws a ProtocolException at:

OutputStream os = conn.getOutputStream();

because it does not enable the output for the URLConnection object. The solution should include this:


to make it work.

Getting msbuild.exe without installing Visual Studio

It used to be installed with the .NET framework. MsBuild v12.0 (2013) is now bundled as a stand-alone utility and has it's own installer.

To reference the location of MsBuild.exe from within an MsBuild script, use the default $(MsBuildToolsPath) property.

What is the difference between <section> and <div>?

In the HTML5 standard, the <section> element is defined as a block of related elements.

The <div> element is defined as a block of children elements.

Visual Studio 2017 error: Unable to start program, An operation is not legal in the current state

For me the issue was signing into my Google account on the debug Chrome window. This had been working fine for me until I signed in. Once I signed out of that instance of Chrome AND choose to delete all of my settings via the checkbox, the debugger worked fine again.

My non-debugging instance of Chrome was still signed into Google and unaffected. The main issue is that my lovely plugins are gone from the debug version, but at least I can step through client code again.

How to convert (transliterate) a string from utf8 to ASCII (single byte) in c#?

Based on Mark's answer above (and Geo's comment), I created a two liner version to remove all ASCII exception cases from a string. Provided for people searching for this answer (as I did).

using System.Text;

// Create encoder with a replacing encoder fallback
var encoder = ASCIIEncoding.GetEncoding("us-ascii", 
    new EncoderReplacementFallback(string.Empty), 
    new DecoderExceptionFallback());

string cleanString = encoder.GetString(encoder.GetBytes(dirtyString)); 

Passing parameters from jsp to Spring Controller method

Use the @RequestParam to pass a parameter to the controller handler method. In the jsp your form should have an input field with name = "id" like the following:

<input type="text" name="id" />
<input type="submit" />

Then in your controller, your handler method should be like the following:

public String listNotes(@RequestParam("id") int id) {
    Person person = personService.getCurrentlyAuthenticatedUser();
    model.addAttribute("person", new Person());
    model.addAttribute("listPersons", this.personService.listPersons());
    model.addAttribute("listNotes", this.notesService.listNotesBySectionId(id, person));
    return "note";

Please also refer to these answers and tutorial:

How do you access a website running on localhost from iPhone browser

Try this:

  1. Press Windows + R
  2. Open cmd
  3. Run ipconfig (Old) ifconfig (New)
  4. Check your wireless network card IP
  5. Go to iPhone and navigate to "" through your browser.
    ( is your IP)

Note: you must set permission on your firewall settings, if any.

How to select a dropdown value in Selenium WebDriver using Java

code to select dropdown using xpath

Select select = new 

code to select particaular option using selectByVisibleText

select.selectByVisibleText(Last 52 Weeks);

Number of occurrences of a character in a string

Your string example looks like the query string part of a GET. If so, note that HttpContext has some help for you

int numberOfArgs = HttpContext.Current.QueryString.Count;

For more of what you can do with QueryString, see NameValueCollection

How to use *ngIf else?

In Angular 4, 5 and 6

We can simply create a template reference variable [2] and link that to the else condition inside an *ngIf directive

The possible Syntaxes [1] are:

<!-- Only If condition -->
<div *ngIf="condition">...</div>
<!-- or -->
<ng-template [ngIf]="condition"><div>...</div></ng-template>

<!-- If and else conditions -->
<div *ngIf="condition; else elseBlock">...</div>
<!-- or -->
<ng-template #elseBlock>...</ng-template>

<!-- If-then-else -->
<div *ngIf="condition; then thenBlock else elseBlock"></div>
<ng-template #thenBlock>...</ng-template>
<ng-template #elseBlock>...</ng-template>

<!-- If and else conditions (storing condition value locally) -->
<div *ngIf="condition as value; else elseBlock">{{value}}</div>
<ng-template #elseBlock>...</ng-template>




How to get an HTML element's style values in javascript?

In jQuery, you can do alert($("#theid").css("width")).

-- if you haven't taken a look at jQuery, I highly recommend it; it makes many simple javascript tasks effortless.


for the record, this post is 5 years old. The web has developed, moved on, etc. There are ways to do this with Plain Old Javascript, which is better.

What is the difference between user variables and system variables?

Just recreate the Path variable in users. Go to user variables, highlight path, then new, the type in value. Look on another computer with same version windows. Usually it is in windows 10: Path %USERPROFILE%\AppData\Local\Microsoft\WindowsApps;

Failed to locate the winutils binary in the hadoop binary path

You can download winutils.exe here:

Then copy it to your HADOOP_HOME/bin directory.

The default XML namespace of the project must be the MSBuild XML namespace

If getting this error trying to build .Net Core 2.0 app on VSTS then ensure your build definition is using the Hosted VS2017 Agent queue.

Openssl : error "self signed certificate in certificate chain"

The solution for the error is to add this line at the top of the code:


What is the cleanest way to get the progress of JQuery ajax request?

jQuery has already implemented promises, so it's better to use this technology and not move events logic to options parameter. I made a jQuery plugin that adds progress promise and now it's easy to use just as other promises:

    /* do some actions */
    /* do something on uploading */

Check it out at github

Class 'DOMDocument' not found

For PHP 7.4 Install the DOM extension.

Debian / Ubuntu:

sudo apt-get update
sudo apt-get install php7.4-xml
sudo service apache2 restart

Centos / Fedora / Red Hat:

yum update
yum install php74w-xml
systemctl restart httpd

For previous PHP releases, replace with your version.

How do I pass an object to HttpClient.PostAsync and serialize as a JSON body?

The straight up answer to your question is: No. The signature for the PostAsync method is as follows:

public Task PostAsync(Uri requestUri, HttpContent content)

So, while you can pass an object to PostAsync it must be of type HttpContent and your anonymous type does not meet that criteria.

However, there are ways to accomplish what you want to accomplish. First, you will need to serialize your anonymous type to JSON, the most common tool for this is Json.NET. And the code for this is pretty trivial:

var myContent = JsonConvert.SerializeObject(data);

Next, you will need to construct a content object to send this data, I will use a ByteArrayContent object, but you could use or create a different type if you wanted.

var buffer = System.Text.Encoding.UTF8.GetBytes(myContent);
var byteContent = new ByteArrayContent(buffer);

Next, you want to set the content type to let the API know this is JSON.

byteContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");

Then you can send your request very similar to your previous example with the form content:

var result = client.PostAsync("", byteContent).Result

On a side note, calling the .Result property like you're doing here can have some bad side effects such as dead locking, so you want to be careful with this.

How to create roles in ASP.NET Core and assign them to users?

I use this (DI):

public class IdentitySeed
    private readonly ApplicationDbContext _context;
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly RoleManager<ApplicationRole> _rolesManager;
    private readonly ILogger _logger;

    public IdentitySeed(
        ApplicationDbContext context,
        UserManager<ApplicationUser> userManager,
        RoleManager<ApplicationRole> roleManager,
         ILoggerFactory loggerFactory) {
        _context = context;
        _userManager = userManager;
        _rolesManager = roleManager;
        _logger = loggerFactory.CreateLogger<IdentitySeed>();

    public async Task CreateRoles() {
        if (await _context.Roles.AnyAsync()) {// not waste time
            _logger.LogInformation("Exists Roles.");
        var adminRole = "Admin";
        var roleNames = new String[] { adminRole, "Manager", "Crew", "Guest", "Designer" };

        foreach (var roleName in roleNames) {
            var role = await _rolesManager.RoleExistsAsync(roleName);
            if (!role) {
                var result = await _rolesManager.CreateAsync(new ApplicationRole { Name = roleName });
                _logger.LogInformation("Create {0}: {1}", roleName, result.Succeeded);
        // administrator
        var user = new ApplicationUser {
            UserName = "Administrator",
            Email = "[email protected]",
            EmailConfirmed = true
        var i = await _userManager.FindByEmailAsync(user.Email);
        if (i == null) {
            var adminUser = await _userManager.CreateAsync(user, "Something*");
            if (adminUser.Succeeded) {
                await _userManager.AddToRoleAsync(user, adminRole);
                _logger.LogInformation("Create {0}", user.UserName);
    //! By: Luis Harvey Triana Vega

How to include js and CSS in JSP with spring MVC

You should put the folder containing css and js files into "webapp/resources". If you've put them in "src/main/java", you must change it. It worked for me.

What are OLTP and OLAP. What is the difference between them?

oltp- mostly used for business transaction.used to collect business data.In sql we use insert,update and delete command for retrieving small source of wise they are highly normalised.... OLTP Mostly used for maintaining the data integrity.

olap- mostly use for reporting,data mining and business analytic purpose. for the large or bulk data.deliberately it is de-normalised. it stores Historical data..

execJs: 'Could not find a JavaScript runtime' but execjs AND therubyracer are in Gemfile

add in your gemfile which is in the folder you have created: gem 'execjs' gem 'therubyracer'

How to make rectangular image appear circular with CSS

Building on the answer from @fzzle - to achieve a circle from a rectangle without defining a fixed height or width, the following will work. The padding-top:100% keeps a 1:1 ratio for the circle-cropper div. Set an inline background image, center it, and use background-size:cover to hide any excess.


.circle-cropper {
  background-repeat: no-repeat;
  background-size: cover;
  background-position: 50%;
  border-radius: 50%;
  width: 100%;
  padding-top: 100%;


<div class="circle-cropper" role="img" style="background-image:url(myrectangle.jpg);"></div>

Using custom fonts using CSS?

Generically, you can use a custom font using @font-face in your CSS. Here's a very basic example:

@font-face {
    font-family: 'YourFontName'; /*a name to be used later*/
    src: url(''); /*URL to font*/

Then, trivially, to use the font on a specific element:

.classname {
    font-family: 'YourFontName';

(.classname is your selector).

Note that certain font-formats don't work on all browsers; you can use's generator to avoid too much effort converting.

You can find a nice set of free web-fonts provided by Google Fonts (also has auto-generated CSS @font-face rules, so you don't have to write your own).

while also preventing people from having free access to download the font, if possible

Nope, it isn't possible to style your text with a custom font embedded via CSS, while preventing people from downloading it. You need to use images, Flash, or the HTML5 Canvas, all of which aren't very practical.

I hope that helped!

Confirmation before closing of tab/browser


function goodbye(e) {
        if(!e) e = window.event;
        //e.cancelBubble is supported by IE - this will kill the bubbling process.
        e.cancelBubble = true;
        e.returnValue = 'You sure you want to leave?'; //This is displayed on the dialog

        //e.stopPropagation works in Firefox.
        if (e.stopPropagation) {

How to get cookie's expire time

When you create a cookie via PHP die Default Value is 0, from the manual:

If set to 0, or omitted, the cookie will expire at the end of the session (when the browser closes)

Otherwise you can set the cookies lifetime in seconds as the third parameter:

But if you mean to get the remaining lifetime of an already existing cookie, i fear that, is not possible (at least not in a direct way).

continuing execution after an exception is thrown in java

If you have a method that you want to throw an error but you want to do some cleanup in your method beforehand you can put the code that will throw the exception inside a try block, then put the cleanup in the catch block, then throw the error.

try {

    //Dangerous code: could throw an error

} catch (Exception e) {

    //Cleanup: make sure that this methods variables and such are in the desired state

    throw e;

This way the try/catch block is not actually handling the error but it gives you time to do stuff before the method terminates and still ensures that the error is passed on to the caller.

An example of this would be if a variable changed in the method then that variable was the cause of an error. It may be desirable to revert the variable.

e.printStackTrace equivalent in python

There is also logging.exception.

import logging


except Exception as ex:
    logging.exception("Something awful happened!")
    # will print this message followed by traceback


ERROR 2007-09-18 23:30:19,913 error 1294 Something awful happened!
Traceback (most recent call last):
  File "", line 22, in f
  File "", line 14, in g
ZeroDivisionError: integer division or modulo by zero

(From via How to print the full traceback without halting the program?)

Label encoding across multiple columns in scikit-learn

Instead of LabelEncoder we can use OrdinalEncoder from scikit learn, which allows multi-column encoding.

Encode categorical features as an integer array. The input to this transformer should be an array-like of integers or strings, denoting the values taken on by categorical (discrete) features. The features are converted to ordinal integers. This results in a single column of integers (0 to n_categories - 1) per feature.

>>> from sklearn.preprocessing import OrdinalEncoder
>>> enc = OrdinalEncoder()
>>> X = [['Male', 1], ['Female', 3], ['Female', 2]]
>>> enc.categories_
[array(['Female', 'Male'], dtype=object), array([1, 2, 3], dtype=object)]
>>> enc.transform([['Female', 3], ['Male', 1]])
array([[0., 2.],
       [1., 0.]])

Both the description and example were copied from its documentation page which you can find here:

How do I check whether input string contains any spaces?

if (str.indexOf(' ') >= 0)

would be (slightly) faster.

Is there a max size for POST parameter content?

There may be a limit depending on server and/or application configuration. For Example, check

Immutable vs Mutable types

First of all, whether a class has methods or what it's class structure is has nothing to do with mutability.

ints and floats are immutable. If I do

a = 1
a += 5

It points the name a at a 1 somewhere in memory on the first line. On the second line, it looks up that 1, adds 5, gets 6, then points a at that 6 in memory -- it didn't change the 1 to a 6 in any way. The same logic applies to the following examples, using other immutable types:

b = 'some string'
b += 'some other string'
c = ('some', 'tuple')
c += ('some', 'other', 'tuple')

For mutable types, I can do thing that actallly change the value where it's stored in memory. With:

d = [1, 2, 3]

I've created a list of the locations of 1, 2, and 3 in memory. If I then do

e = d

I just point e to the same list d points at. I can then do:

e += [4, 5]

And the list that both e and d points at will be updated to also have the locations of 4 and 5 in memory.

If I go back to an immutable type and do that with a tuple:

f = (1, 2, 3)
g = f
g += (4, 5)

Then f still only points to the original tuple -- you've pointed g at an entirely new tuple.

Now, with your example of

class SortedKeyDict(dict):
    def __new__(cls, val):
        return dict.__new__(cls, val.clear())

Where you pass

d = (('zheng-cai', 67), ('hui-jun', 68),('xin-yi', 2))

(which is a tuple of tuples) as val, you're getting an error because tuples don't have a .clear() method -- you'd have to pass dict(d) as val for it to work, in which case you'll get an empty SortedKeyDict as a result.

Best XML parser for Java

I have found dom4j to be the tool for working with XML. Especially compared to Xerces.

Numpy: Checking if a value is NaT

This approach avoids the warnings while preserving the array-oriented evaluation.

import numpy as np
def isnat(x):
    datetime64 analog to isnan.
    doesn't yet exist in numpy - other ways give warnings
    and are likely to change.  
    return x.astype('i8') == np.datetime64('NaT').astype('i8')

Get image dimensions

Using getimagesize function, we can also get these properties of that specific image-


list($width, $height, $type, $attr) = getimagesize("image_name.jpg");

echo "Width: " .$width. "<br />";
echo "Height: " .$height. "<br />";
echo "Type: " .$type. "<br />";
echo "Attribute: " .$attr. "<br />";

//Using array
$arr = array('h' => $height, 'w' => $width, 't' => $type, 'a' => $attr);

Result like this -

Width: 200
Height: 100
Type: 2
Attribute: width='200' height='100'

Type of image consider like -

1 = GIF
2 = JPG
3 = PNG
4 = SWF
5 = PSD
6 = BMP
7 = TIFF(intel byte order)
8 = TIFF(motorola byte order)
9 = JPC
10 = JP2
11 = JPX
12 = JB2
13 = SWC
14 = IFF
15 = WBMP
16 = XBM

Convert Json Array to normal Java list

Maybe it's only a workaround (not very efficient) but you could do something like this:

String[] resultingArray = yourJSONarray.join(",").split(",");

Obviously you can change the ',' separator with anything you like (I had a JSONArray of email addresses)

List files with certain extensions with ls and grep

Use regular expressions with find:

find . -iregex '.*\.\(mp3\|mp4\|exe\)' -printf '%f\n'

If you're piping the filenames:

find . -iregex '.*\.\(mp3\|mp4\|exe\)' -printf '%f\0' | xargs -0 dosomething

This protects filenames that contain spaces or newlines.

OS X find only supports alternation when the -E (enhanced) option is used.

find -E . -regex '.*\.(mp3|mp4|exe)'

SQLite string contains other string query

While LIKE is suitable for this case, a more general purpose solution is to use instr, which doesn't require characters in the search string to be escaped. Note: instr is available starting from Sqlite 3.7.15.

 WHERE instr(column, 'cats') > 0;

Also, keep in mind that LIKE is case-insensitive, whereas instr is case-sensitive.

How can I change the class of an element with jQuery>

To set a class completely, instead of adding one or removing one, use this:


Advantage of this is that you'll remove any class that might be set in there and reset it to how you like. At least this worked for me in one situation.

How to see indexes for a database or table in MySQL?

You could use this query to get the no of indexes as well as the index names of each table in specified database.

       COUNT(1) index_count,
       GROUP_CONCAT(DISTINCT(index_name) SEPARATOR ',\n ') indexes
      AND INDEX_NAME != 'primary'

How to configure socket connect timeout

I just wrote an extension class in order to allow timeouts in connections. Use it exactly as you would use the standard Connect() methods, with an extra parameter named timeout.

using System;
using System.Net;
using System.Net.Sockets;

/// <summary>
/// Extensions to Socket class
/// </summary>
public static class SocketExtensions
    /// <summary>
    /// Connects the specified socket.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="host">The host.</param>
    /// <param name="port">The port.</param>
    /// <param name="timeout">The timeout.</param>
    public static void Connect(this Socket socket, string host, int port, TimeSpan timeout)
        AsyncConnect(socket, (s, a, o) => s.BeginConnect(host, port, a, o), timeout);

    /// <summary>
    /// Connects the specified socket.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="addresses">The addresses.</param>
    /// <param name="port">The port.</param>
    /// <param name="timeout">The timeout.</param>
    public static void Connect(this Socket socket, IPAddress[] addresses, int port, TimeSpan timeout)
        AsyncConnect(socket, (s, a, o) => s.BeginConnect(addresses, port, a, o), timeout);

    /// <summary>
    /// Asyncs the connect.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="connect">The connect.</param>
    /// <param name="timeout">The timeout.</param>
    private static void AsyncConnect(Socket socket, Func<Socket, AsyncCallback, object, IAsyncResult> connect, TimeSpan timeout)
        var asyncResult = connect(socket, null, null);
        if (!asyncResult.AsyncWaitHandle.WaitOne(timeout))
            catch (SocketException)
            { }
            catch (ObjectDisposedException)
            { }

C# Switch-case string starting with

If all the cases have the same length you can use
switch (mystring.SubString(0,Math.Min(len, mystring.Length))).
Another option is to have a function that will return categoryId based on the string and switch on the id.

How to convert a date String to a Date or Calendar object?

The highly regarded Joda Time library is also worth a look. This is basis for the new date and time api that is pencilled in for Java 7. The design is neat, intuitive, well documented and avoids a lot of the clumsiness of the original java.util.Date / java.util.Calendar classes.

Joda's DateFormatter can parse a String to a Joda DateTime.

React Native: How to select the next TextInput after pressing the "next" keyboard button?

Here a reagent solution for a input component that has a :focus property.

The field will be focused as long as this prop is set to true and will not have focus as long as this is false.

Unfortunately this component needs to have a :ref defined, I could not find an other way to call .focus() on it. I am happy about suggestions.

(defn focusable-input [init-attrs]
    {:display-name "focusable-input"
       (fn [this new-argv]
         (let [ref-c (aget this "refs" (:ref init-attrs))
               focus (:focus (ru/extract-props new-argv))
               is-focused (.isFocused ref-c)]
           (if focus
             (when-not is-focused (.focus ref-c))
             (when is-focused (.blur ref-c)))))
       (fn [attrs]
         (let [init-focus (:focus init-attrs)
               auto-focus (or (:auto-focus attrs) init-focus)
               attrs (assoc attrs :auto-focus auto-focus)]
           [input attrs]))}))

An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

I removed my .classpath file in my project directory to correct this issue. No need to remove the Maven Nature from the project in Eclipse.

The specific error I was getting was: Project 'my-project-name' is missing required Java project: 'org.some.package-9.3.0 But my project wasn't dependent on org.some.package in any way.

Perhaps an old version of the project relied on it and Maven wasn't properly updating the .classpath file.

Just what is an IntPtr exactly?

It's a "native (platform-specific) size integer." It's internally represented as void* but exposed as an integer. You can use it whenever you need to store an unmanaged pointer and don't want to use unsafe code. IntPtr.Zero is effectively NULL (a null pointer).

Fatal error: Maximum execution time of 30 seconds exceeded

I have same problem in WordPress site, I added in .htaccess file then working fine for me.

php_value max_execution_time 6000000

How to turn a string formula into a "real" formula

The best, non-VBA, way to do this is using the TEXT formula. It takes a string as an argument and converts it to a value.

For example, =TEXT ("0.4*A1",'##') will return the value of 0.4 * the value that's in cell A1 of that worksheet.

How to run php files on my computer

You have to run a web server (e.g. Apache) and browse to your localhost, mostly likely on port 80.

What you really ought to do is install an all-in-one package like XAMPP, it bundles Apache, MySQL PHP, and Perl (if you were so inclined) as well as a few other tools that work with Apache and MySQL - plus it's cross platform (that's what the 'X' in 'XAMPP' stands for).

Once you install XAMPP (and there is an installer, so it shouldn't be hard) open up the control panel for XAMPP and then click the "Start" button next to Apache - note that on applications that require a database, you'll also need to start MySQL (and you'll be able to interface with it through phpMyAdmin). Once you've started Apache, you can browse to http://localhost.

Again, regardless of whether or not you choose XAMPP (which I would recommend), you should just have to start Apache.

PHP error: "The zip extension and unzip command are both missing, skipping."

I had PHP7.2 on a Ubuntu 16.04 server and it solved my problem:

sudo apt-get install zip unzip php-zip


Tried this for Ubuntu 18.04 and worked as well.

How to check if a String is numeric in Java

As @CraigTP had mentioned in his excellent answer, I also have similar performance concerns on using Exceptions to test whether the string is numerical or not. So I end up splitting the string and use java.lang.Character.isDigit().

public static boolean isNumeric(String str)
    for (char c : str.toCharArray())
        if (!Character.isDigit(c)) return false;
    return true;

According to the Javadoc, Character.isDigit(char) will correctly recognizes non-Latin digits. Performance-wise, I think a simple N number of comparisons where N is the number of characters in the string would be more computationally efficient than doing a regex matching.

UPDATE: As pointed by Jean-François Corbett in the comment, the above code would only validate positive integers, which covers the majority of my use case. Below is the updated code that correctly validates decimal numbers according to the default locale used in your system, with the assumption that decimal separator only occur once in the string.

public static boolean isStringNumeric( String str )
    DecimalFormatSymbols currentLocaleSymbols = DecimalFormatSymbols.getInstance();
    char localeMinusSign = currentLocaleSymbols.getMinusSign();

    if ( !Character.isDigit( str.charAt( 0 ) ) && str.charAt( 0 ) != localeMinusSign ) return false;

    boolean isDecimalSeparatorFound = false;
    char localeDecimalSeparator = currentLocaleSymbols.getDecimalSeparator();

    for ( char c : str.substring( 1 ).toCharArray() )
        if ( !Character.isDigit( c ) )
            if ( c == localeDecimalSeparator && !isDecimalSeparatorFound )
                isDecimalSeparatorFound = true;
            return false;
    return true;

How do I load an HTTP URL with App Transport Security enabled in iOS 9?

I have solved as plist file.

  1. Add a NSAppTransportSecurity : Dictionary.
  2. Add Subkey named " NSAllowsArbitraryLoads " as Boolean : YES

enter image description here

How to check if a file contains a specific string using Bash

grep -q "something" file
[[ !? -eq 0 ]] && echo "yes" || echo "no"

Show div on scrollDown after 800px

You've got a few things going on there. One, why a class? Do you actually have multiple of these on the page? The CSS suggests you can't. If not you should use an ID - it's faster to select both in CSS and jQuery:

<div id=bottomMenu>You read it all.</div>

Second you've got a few crazy things going on in that CSS - in particular the z-index is supposed to just be a number, not measured in pixels. It specifies what layer this tag is on, where each higher number is closer to the user (or put another way, on top of/occluding tags with lower z-indexes).

The animation you're trying to do is basically .fadeIn(), so just set the div to display: none; initially and use .fadeIn() to animate it:


.fadeIn() works by first doing display: (whatever the proper display property is for the tag), opacity: 0, then gradually ratcheting up the opacity.

Full working example:


#bottomMenu {
    display: none;
    position: fixed;
    left: 0; bottom: 0;
    width: 100%; height: 60px;
    border-top: 1px solid #000;
    background: #fff;
    z-index: 1;


var $win = $(window);

function checkScroll() {
    if ($win.scrollTop() > 100) {
        $'scroll', checkScroll);


NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference

This issue is due to ArrayList variable not being instantiated. Need to declare "recordings" variable like following, that should solve the issue;

ArrayList<String> recordings = new ArrayList<String>();

this calls default constructor and assigns empty string to the recordings variable so that it is not null anymore.

How to do date/time comparison

Use the time package to work with time information in Go.

Time instants can be compared using the Before, After, and Equal methods. The Sub method subtracts two instants, producing a Duration. The Add method adds a Time and a Duration, producing a Time.

Play example:

package main

import (

func inTimeSpan(start, end, check time.Time) bool {
    return check.After(start) && check.Before(end)

func main() {
    start, _ := time.Parse(time.RFC822, "01 Jan 15 10:00 UTC")
    end, _ := time.Parse(time.RFC822, "01 Jan 16 10:00 UTC")

    in, _ := time.Parse(time.RFC822, "01 Jan 15 20:00 UTC")
    out, _ := time.Parse(time.RFC822, "01 Jan 17 10:00 UTC")

    if inTimeSpan(start, end, in) {
        fmt.Println(in, "is between", start, "and", end, ".")

    if !inTimeSpan(start, end, out) {
        fmt.Println(out, "is not between", start, "and", end, ".")

How to replace string in Groovy

You need to escape the backslash \:

println yourString.replace("\\", "/")

How to combine GROUP BY and ROW_NUMBER?

The deduplication (to select the max T1) and the aggregation need to be done as distinct steps. I've used a CTE since I think this makes it clearer:

    SELECT  Rel.t2ID, SUM(Price) price
    FROM    @t1         AS T1
    JOIN    @relation   AS Rel 
    ON      Rel.t1ID=T1.ID
    BY      Rel.t2ID
    SELECT  Rel.t2ID, Rel.t1ID, 
            ROW_NUMBER()OVER(Partition By Rel.t2ID Order By Price DESC)As PriceList
    FROM    @t1         AS T1
    JOIN    @relation   AS Rel 
    ON      Rel.t1ID=T1.ID
,T2.Name as T2Name
,T1.Name As T1Name
FROM    @t2 AS T2
JOIN    sumCTE AS sumT1
ON      sumT1.t2ID = t2.ID
JOIN    maxCTE AS maxT1
ON      maxT1.t2ID = t2.ID
JOIN    @t1 AS T1
ON      T1.ID = maxT1.t1ID
WHERE   maxT1.PriceList = 1

How to get child element by ID in JavaScript?

Here is a pure JavaScript solution (without jQuery)

var _Utils = function ()
    this.findChildById = function (element, childID, isSearchInnerDescendant) // isSearchInnerDescendant <= true for search in inner childern 
        var retElement = null;
        var lstChildren = isSearchInnerDescendant ? Utils.getAllDescendant(element) : element.childNodes;

        for (var i = 0; i < lstChildren.length; i++)
            if (lstChildren[i].id == childID)
                retElement = lstChildren[i];

        return retElement;

    this.getAllDescendant = function (element, lstChildrenNodes)
        lstChildrenNodes = lstChildrenNodes ? lstChildrenNodes : [];

        var lstChildren = element.childNodes;

        for (var i = 0; i < lstChildren.length; i++) 
            if (lstChildren[i].nodeType == 1) // 1 is 'ELEMENT_NODE'
                lstChildrenNodes = Utils.getAllDescendant(lstChildren[i], lstChildrenNodes);

        return lstChildrenNodes;
var Utils = new _Utils;

Example of use:

var myDiv = document.createElement("div");
myDiv.innerHTML = "<table id='tableToolbar'>" +
                        "<tr>" +
                            "<td>" +
                                "<div id='divIdToSearch'>" +
                                "</div>" +
                            "</td>" +
                        "</tr>" +

var divToSearch = Utils.findChildById(myDiv, "divIdToSearch", true);

How to check if an email address exists without sending an email?

I think you cannot, there are so many scenarios where even sending an e-mail can fail. Eg. mail server on the user side is temporarily down, mailbox exists but is full so message cannot be delivered, etc.

That's probably why so many sites validate a registration after the user confirmed they have received the confirmation e-mail.

what's data-reactid attribute in html?

That's the HTML data attribute. See this for more detail:

Basically it's just a container of your custom data while still making the HTML valid. It's data- plus some unique identifier.

Capturing mobile phone traffic on Wireshark

Install Fiddler on your PC and use it as a proxy on your Android device.


What exactly does += do in python?

Note x += y is not the same as x = x + y in some situations where an additional operator is included because of the operator precedence combined with the fact that the right hand side is always evaluated first, e.g.

>>> x = 2
>>> x += 2 and 1
>>> x

>>> x = 2
>>> x = x + 2 and 1
>>> x

Note the first case expand to:

>>> x = 2
>>> x = x + (2 and 1)
>>> x

You are more likely to encounter this in the 'real world' with other operators, e.g.

x *= 2 + 1 == x = x * (2 + 1) != x = x * 2 + 1

Run Android studio emulator on AMD processor

I have a Ryzen 2600X and I am able to run the emulator without problems. Here are the tweaks I made:

*NOTE: You don't need the beta version of Android Studio or Android Emulator.

  1. Go to the MB bios and turn SVM on (CPU Virtualization).
  2. In Windows right click Windows Button => Select "Apps and Features" => "Programs and features" => "Turn Windows Features on and off"
  3. In the displayed list select Hyper-V checkbox == Make sure the subfolders are all selected. When prompted to restart, restart the PC.
  4. After restart and update instalation screen you are back in Windows and you should be able to run the Emulator.

**Note: I have selected x86_64 and plain x86 images(both API 28) from the x86 Images tab and they work just fine.

***Note: Might also check for Android Licenses if errors pop up, I had an issue because of this while using Flutter, maybe it's related to that.

Read the current full URL with React?

window.location.href is what you're looking for.

Visual Studio 2010 - recommended extensions

CodeMaid seems to be pretty useful - it AutoFormats on save which saves a lot of time between developers and code-diffs. (Are there other tools that can use the VS AutoFormat document?)

SQL Query To Obtain Value that Occurs more than once

For SQL Server 2005+

       COUNT(*) OVER (PARTITION BY Lastname) as Cnt
FROM Students
SELECT * /*TODO: Add column list. Don't use "*"                   */
WHERE Cnt >= 3

How can I get zoom functionality for images?

I just integrated Robert Foss's TouchImageView: it worked perfectly out of the box! Thanks!

I just modified a bit the code so I could be able to instantiate it from my layout.xml.

Just add two constructors

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

public TouchImageView(Context context) {

and transform the old constructor into an init method:

private void init(Context context){
    //...old code ofconstructor of Robert Moss's code

Check status of one port on remote host

Press Windows + R type cmd and Enter

In command prompt type

telnet "machine name/ip" "port number"

If port is not open, this message will display:

"Connecting To "machine name"...Could not open connection to the host, on port "port number":

Otherwise you will be take in to opened port (empty screen will display)

React - How to pass HTML tags in props?

<MyComponent text={<span>This is <strong>not</strong> working.</span>} />

and then in your component you can do prop checking like so:

import React from 'react';
export default class MyComponent extends React.Component {
  static get propTypes() {
    return {
      text: React.PropTypes.object, // if you always want react components
      text: React.PropTypes.any, // if you want both text or react components

Make sure you choose only one prop type.

DataTables: Uncaught TypeError: Cannot read property 'defaults' of undefined

The problem is that dataTable is not defined at the point you are calling this method.

Ensure that you are loading the .js files in the correct order:

<script src="/Scripts/jquery.dataTables.js"></script>
<script src="/Scripts/dataTables.bootstrap.js"></script>

Convert Variable Name to String?

What are you trying to achieve? There is absolutely no reason to ever do what you describe, and there is likely a much better solution to the problem you're trying to solve..

The most obvious alternative to what you request is a dictionary. For example:

>>> my_data = {'var': 'something'}
>>> my_data['something_else'] = 'something'
>>> print my_data.keys()
['var', 'something_else']
>>> print my_data['var']

Mostly as a.. challenge, I implemented your desired output. Do not use this code, please!

#!/usr/bin/env python2.6
class NewLocals:
    """Please don't ever use this code.."""
    def __init__(self, initial_locals):
        self.prev_locals = list(initial_locals.keys())

    def show_new(self, new_locals):
        output = ", ".join(list(set(new_locals) - set(self.prev_locals)))
        self.prev_locals = list(new_locals.keys())
        return output
# Set up
eww = None
eww = NewLocals(locals())

# "Working" requested code

var = {}

print eww.show_new(locals())  # Outputs: var

something_else = 3
print eww.show_new(locals()) # Outputs: something_else

# Further testing

another_variable = 4
and_a_final_one = 5

print eww.show_new(locals()) # Outputs: another_variable, and_a_final_one

Variable number of arguments in C++?

In C++11 you have two new options, as the Variadic functions reference page in the Alternatives section states:

  • Variadic templates can also be used to create functions that take variable number of arguments. They are often the better choice because they do not impose restrictions on the types of the arguments, do not perform integral and floating-point promotions, and are type safe. (since C++11)
  • If all variable arguments share a common type, a std::initializer_list provides a convenient mechanism (albeit with a different syntax) for accessing variable arguments.

Below is an example showing both alternatives (see it live):

#include <iostream>
#include <string>
#include <initializer_list>

template <typename T>
void func(T t) 
    std::cout << t << std::endl ;

template<typename T, typename... Args>
void func(T t, Args... args) // recursive variadic function
    std::cout << t <<std::endl ;

    func(args...) ;

template <class T>
void func2( std::initializer_list<T> list )
    for( auto elem : list )
        std::cout << elem << std::endl ;

int main()
        str1( "Hello" ),
        str2( "world" );


    func2( {10, 20, 30, 40 }) ;
    func2( {str1, str2 } ) ;

If you are using gcc or clang we can use the PRETTY_FUNCTION magic variable to display the type signature of the function which can be helpful in understanding what is going on. For example using:

std::cout << __PRETTY_FUNCTION__ << ": " << t <<std::endl ;

would results int following for variadic functions in the example (see it live):

void func(T, Args...) [T = int, Args = <double, char, std::basic_string<char>>]: 1
void func(T, Args...) [T = double, Args = <char, std::basic_string<char>>]: 2.5
void func(T, Args...) [T = char, Args = <std::basic_string<char>>]: a
void func(T) [T = std::basic_string<char>]: Hello

In Visual Studio you can use FUNCSIG.

Update Pre C++11

Pre C++11 the alternative for std::initializer_list would be std::vector or one of the other standard containers:

#include <iostream>
#include <string>
#include <vector>

template <class T>
void func1( std::vector<T> vec )
    for( typename std::vector<T>::iterator iter = vec.begin();  iter != vec.end(); ++iter )
        std::cout << *iter << std::endl ;

int main()
    int arr1[] = {10, 20, 30, 40} ;
    std::string arr2[] = { "hello", "world" } ; 
    std::vector<int> v1( arr1, arr1+4 ) ;
    std::vector<std::string> v2( arr2, arr2+2 ) ;

    func1( v1 ) ;
    func1( v2 ) ;

and the alternative for variadic templates would be variadic functions although they are not type-safe and in general error prone and can be unsafe to use but the only other potential alternative would be to use default arguments, although that has limited use. The example below is a modified version of the sample code in the linked reference:

#include <iostream>
#include <string>
#include <cstdarg>

void simple_printf(const char *fmt, ...)
    va_list args;
    va_start(args, fmt);

    while (*fmt != '\0') {
        if (*fmt == 'd') {
            int i = va_arg(args, int);
            std::cout << i << '\n';
        } else if (*fmt == 's') {
            char * s = va_arg(args, char*);
            std::cout << s << '\n';


int main()
        str1( "Hello" ),
        str2( "world" );

    simple_printf("dddd", 10, 20, 30, 40 );
    simple_printf("ss", str1.c_str(), str2.c_str() ); 

    return 0 ;

Using variadic functions also comes with restrictions in the arguments you can pass which is detailed in the draft C++ standard in section 5.2.2 Function call paragraph 7:

When there is no parameter for a given argument, the argument is passed in such a way that the receiving function can obtain the value of the argument by invoking va_arg (18.7). The lvalue-to-rvalue (4.1), array-to-pointer (4.2), and function-to-pointer (4.3) standard conversions are performed on the argument expression. After these conversions, if the argument does not have arithmetic, enumeration, pointer, pointer to member, or class type, the program is ill-formed. If the argument has a non-POD class type (clause 9), the behavior is undefined. [...]

Does .NET provide an easy way convert bytes to KB, MB, GB, etc.?

let scaleBytes (value : float) : float * string =
    let log2 x = log x / log 2.
    let prefixes = [| ""; "Ki"; "Mi"; "Gi"; "Ti"; "Pi" |] // note the capital K and the 'i'
    let index = int (log2 value) / 10
    1. / 2.**(float index * 10.),
sprintf "%s%s" prefixes.[index] (Units.symbol Bytes)

(DISCLAIMER: I wrote this code, even the code in the link!)

How to use android emulator for testing bluetooth application?

You can't. The emulator does not support Bluetooth, as mentioned in the SDK's docs and several other places. Android emulator does not have bluetooth capabilities".

You can only use real devices.

Emulator Limitations

The functional limitations of the emulator include:

  • No support for placing or receiving actual phone calls. However, You can simulate phone calls (placed and received) through the emulator console
  • No support for USB
  • No support for device-attached headphones
  • No support for determining SD card insert/eject
  • No support for WiFi, Bluetooth, NFC

Refer to the documentation

Task.Run with Parameter(s)?

Use variable capture to "pass in" parameters.

var x = rawData;
Task.Run(() =>
    // Do something with 'x'

You also could use rawData directly but you must be careful, if you change the value of rawData outside of a task (for example a iterator in a for loop) it will also change the value inside of the task.

jQuery: Get selected element tag name

You should NOT use jQuery('selector').attr("tagName").toLowerCase(), because it only works in older versions of Jquery.

You could use $('selector').prop("tagName").toLowerCase() if you're certain that you're using a version of jQuery thats >= version 1.6.

Note :

You may think that EVERYONE is using jQuery 1.10+ or something by now (January 2016), but unfortunately that isn't really the case. For example, many people today are still using Drupal 7, and every official release of Drupal 7 to this day includes jQuery 1.4.4 by default.

So if do not know for certain if your project will be using jQuery 1.6+, consider using one of the options that work for ALL versions of jQuery :

Option 1 :


Option 2


How do I add indices to MySQL tables?

It's worth noting that multiple field indexes can drastically improve your query performance. So in the above example we assume ProductID is the only field to lookup but were the query to say ProductID = 1 AND Category = 7 then a multiple column index helps. This is achieved with the following:

ALTER TABLE `table` ADD INDEX `index_name` (`col1`,`col2`)

Additionally the index should match the order of the query fields. In my extended example the index should be (ProductID,Category) not the other way around.

When should I use "this" in a class?

Unless you have overlapping variable names, its really just for clarity when you're reading the code.

Getting Error:JRE_HOME variable is not defined correctly when trying to run startup.bat of Apache-Tomcat

Got the solution and it's working fine. Set the environment variables as:

  • CATALINA_HOME=C:\Program Files\Java\apache-tomcat-7.0.59\apache-tomcat-7.0.59 (path where your Apache Tomcat is)
  • JAVA_HOME=C:\Program Files\Java\jdk1.8.0_25; (path where your JDK is)
  • JRE_Home=C:\Program Files\Java\jre1.8.0_25; (path where your JRE is)

Getting Current date, time , day in laravel

//vanilla php
Class Date {
    public static function date_added($time){
         date_default_timezone_set('Africa/Lagos');//or choose your location
        return date('l F Y g:i:s ',$time);



JQuery Calculate Day Difference in 2 date textboxes


   var edate = new Date($('#edate').val());
   var sdate = new Date($('#sdate').val());
   days = (edate- sdate) / (1000 * 60 * 60 * 24);
   alert (days);

Regex pattern including all special characters

Use this regular expression pattern ("^[a-zA-Z0-9]*$") .It validates alphanumeric string excluding the special characters

Download a file from NodeJS Server using Express


Express has a helper for this to make life easier.

app.get('/download', function(req, res){
  const file = `${__dirname}/upload-folder/dramaticpenguin.MOV`;; // Set disposition and send it.

Old Answer

As far as your browser is concerned, the file's name is just 'download', so you need to give it more info by using another HTTP header.

res.setHeader('Content-disposition', 'attachment; filename=dramaticpenguin.MOV');

You may also want to send a mime-type such as this:

res.setHeader('Content-type', 'video/quicktime');

If you want something more in-depth, here ya go.

var path = require('path');
var mime = require('mime');
var fs = require('fs');

app.get('/download', function(req, res){

  var file = __dirname + '/upload-folder/dramaticpenguin.MOV';

  var filename = path.basename(file);
  var mimetype = mime.lookup(file);

  res.setHeader('Content-disposition', 'attachment; filename=' + filename);
  res.setHeader('Content-type', mimetype);

  var filestream = fs.createReadStream(file);

You can set the header value to whatever you like. In this case, I am using a mime-type library - node-mime, to check what the mime-type of the file is.

Another important thing to note here is that I have changed your code to use a readStream. This is a much better way to do things because using any method with 'Sync' in the name is frowned upon because node is meant to be asynchronous.

Getting PEAR to work on XAMPP (Apache/MySQL stack on Windows)

Another gotcha for this kind of problem: avoid running pear within a Unix shell (e.g., Git Bash or Cygwin) on a Windows machine. I had the same problem and the path fix suggested above didn't help. Switched over to a Windows shell, and the pear command works as expected.

Way to ng-repeat defined number of times instead of repeating over array?

Easiest answer: 2 lines of code

JS (in your AngularJS controller)

$scope.range = new Array(MAX_REPEATS); // set MAX_REPEATS to the most repetitions you will ever need in a single ng-repeat that makes use of this strategy


<div ng-repeat="i in range.slice(0,repeatCount) track by $index"></div>

...where repeatCount is the number of repetitions that should appear in this location.

Java; String replace (using regular expressions)?

"5 * x^3 - 6 * x^1 + 1".replaceAll("\\W*\\*\\W*","").replaceAll("\\^(\\d+)","<sup>$1</sup>");

please note that joining both replacements in a single regex/replacement would be a bad choice because more general expressions such as x^3 - 6 * x would fail.

Adding horizontal spacing between divs in Bootstrap 3

The best solution is not to use the same element for column and panel:

<div class="row">
    <div class="col-md-3">
        <div class="panel" id="gameplay-away-team">Away Team</div>
    <div class="col-md-6">
        <div class="panel" id="gameplay-baseball-field">Baseball Field</div>
    <div class="col-md-3">
        <div class="panel" id="gameplay-home-team">Home Team</div>

and some more styles:

#gameplay-baseball-field {
  padding-right: 10px;
  padding-left: 10px;

How can I regenerate ios folder in React Native project?

? react-native eject

error Unrecognized command "eject". info Run "react-native --help" to see a list of all available commands.

? react-native upgrade --legacy true

error: unknown option `--legacy'

You can init a new project that's named the same in another folder and copy ios dir over:

inside YourProjectName directory

npx react-native init YourProjectName
mv YourProjectName/ios ios
rm -rf YourProjectName

Make sure you have clean git history before doing so, in case you need to revert

How do I print the percent sign(%) in c

Try printing out this way


ASP.NET MVC Bundle not rendering script files on staging server. It works on development server

Things to check when enabling the bundle optimization;

BundleTable.EnableOptimizations = true;


webconfig debug = "false"
  1. the bundles.IgnoreList.Clear();

this will ignore the minified assets of your bundles like *.min.css or *.min.js which can cause an undefine error of your script. To fix is replace the .min asset to original. if you do this you may not need the bundles.IgnoreList.Clear(); e.g.

bundles.Add(new ScriptBundle("~/bundles/datatablesjs")
      .Include("~/Scripts/datatables.min.js") <---- change this to non minified ver.
  1. Make sure the names of the bundles of your css and js are unique.

    bundles.Add(new StyleBundle("~/bundles/datatablescss").Include( ...) );

    bundles.Add(new ScriptBundle("~/bundles/datatablesjs").Include( ...) );

  2. Make sure you use the Render name of your @Script.Render and Style.Render are the same on your bundle config. e.g.



Django REST Framework: adding additional field to ModelSerializer

My response to a similar question (here) might be useful.

If you have a Model Method defined in the following way:

class MyModel(models.Model):

    def model_method(self):
        return "some_calculated_result"

You can add the result of calling said method to your serializer like so:

class MyModelSerializer(serializers.ModelSerializer):
    model_method_field = serializers.CharField(source='model_method')

p.s. Since the custom field isn't really a field in your model, you'll usually want to make it read-only, like so:

class Meta:
    model = MyModel
    read_only_fields = (

How to view the current heap size that an application is using?

Use this code:

// Get current size of heap in bytes
long heapSize = Runtime.getRuntime().totalMemory(); 

// Get maximum size of heap in bytes. The heap cannot grow beyond this size.// Any attempt will result in an OutOfMemoryException.
long heapMaxSize = Runtime.getRuntime().maxMemory();

 // Get amount of free memory within the heap in bytes. This size will increase // after garbage collection and decrease as new objects are created.
long heapFreeSize = Runtime.getRuntime().freeMemory(); 

It was useful to me to know it.

Cannot overwrite model once compiled Mongoose

This problem might occur if you define 2 different schema's with same Collection name

How to download python from command-line?

wget --no-check-certificate
tar -xzf Python-2.7.11.tgz  
cd Python-2.7.11

Now read the README file to figure out how to install, or do the following with no guarantees from me that it will be exactly what you need.

sudo make install  

For Python 3.5 use the following download address:

For other versions and the most up to date download links:

Calling class staticmethod within the class body?

If the "core problem" is assigning class variables using functions, an alternative is to use a metaclass (it's kind of "annoying" and "magical" and I agree that the static method should be callable inside the class, but unfortunately it isn't). This way, we can refactor the behavior into a standalone function and don't clutter the class.

class KlassMetaClass(type(object)):
    def _stat_func():
        return 42

    def __new__(cls, clsname, bases, attrs):
        # Call the __new__ method from the Object metaclass
        super_new = super().__new__(cls, clsname, bases, attrs)
        # Modify class variable "_ANS"
        super_new._ANS = cls._stat_func()
        return super_new

class Klass(object, metaclass=KlassMetaClass):
    Class that will have class variables set pseudo-dynamically by the metaclass

print(Klass._ANS) # prints 42

Using this alternative "in the real world" may be problematic. I had to use it to override class variables in Django classes, but in other circumstances maybe it's better to go with one of the alternatives from the other answers.

Simplest code for array intersection in javascript

function intersectionOfArrays(arr1, arr2) {
    return arr1.filter((element) => arr2.indexOf(element) !== -1).filter((element, pos, self) => self.indexOf(element) == pos);

How to pass data from child component to its parent in ReactJS?

I found the approach how to get data from child component in parents when i need it.


class ParentComponent extends Component{
  onSubmit(data) {
    let mapPoint = this.getMapPoint();

    return (
      <form onSubmit={this.onSubmit.bind(this)}>
        <ChildComponent getCurrentPoint={getMapPoint => {this.getMapPoint = getMapPoint}} />
        <input type="submit" value="Submit" />


class ChildComponent extends Component{

    if (props.getCurrentPoint){

    return this.Point;

This example showing how to pass function from child component to parent and use this function to get data from child.

file_get_contents(): SSL operation failed with code 1, Failed to enable crypto

You basically have to set the environment variable SSL_CERT_FILE to the path of the PEM file of the ssl-certificate downloaded from the following link :

It took me a lot of time to figure this out.

Adding content to a linear layout dynamically?

LinearLayout layout = (LinearLayout)findViewById(;
View child = getLayoutInflater().inflate(R.layout.child, null);

What is the best way to add options to a select from a JavaScript object with jQuery?

I decided to chime in a bit.

  1. Deal with prior selected option; some browsers mess up when we append
  2. ONLY hit DOM once with the append
  3. Deal with multiple property while adding more options
  4. Show how to use an object
  5. Show how to map using an array of objects

// objects as value/desc_x000D_
let selectValues = {_x000D_
  "1": "test 1",_x000D_
  "2": "test 2",_x000D_
  "3": "test 3",_x000D_
  "4": "test Four"_x000D_
//use div here as using "select" mucks up the original selected value in "mySelect"_x000D_
let opts = $("<div />");_x000D_
let opt = {};_x000D_
$.each(selectValues, function(value, desc) {_x000D_
  opts.append($('<option />').prop("value", value).text(desc));_x000D_
// array of objects called "options" in an object_x000D_
let selectValuesNew = {_x000D_
  options: [{_x000D_
      value: "1",_x000D_
      description: "2test 1"_x000D_
      value: "2",_x000D_
      description: "2test 2",_x000D_
      selected: true_x000D_
      value: "3",_x000D_
      description: "2test 3"_x000D_
      value: "4",_x000D_
      description: "2test Four"_x000D_
//use div here as using "select" mucks up the original selected value_x000D_
let opts2 = $("<div />");_x000D_
let opt2 = {}; //only append after adding all options_x000D_
$.map(selectValuesNew.options, function(val, index) {_x000D_
  opts2.append($('<option />')_x000D_
    .prop("value", val.value)_x000D_
    .prop("selected", val.selected)_x000D_
<script src=""></script>_x000D_
<select id="mySelect">_x000D_
  <option value="" selected="selected">empty</option>_x000D_
<select id="mySelectNew" multiple="multiple">_x000D_
  <option value="" selected="selected">2empty</option>_x000D_

How to split strings into text and number?

This is a little longer, but more versatile for cases where there are multiple, randomly placed, numbers in the string. Also, it requires no imports.

def getNumbers( input ):
    # Collect Info
    compile = ""
    complete = []

    for letter in input:
        # If compiled string
        if compile:
            # If compiled and letter are same type, append letter
            if compile.isdigit() == letter.isdigit():
                compile += letter
            # If compiled and letter are different types, append compiled string, and begin with letter
                complete.append( compile )
                compile = letter
        # If no compiled string, begin with letter
            compile = letter
    # Append leftover compiled string
    if compile:
        complete.append( compile )
    # Return numbers only
    numbers = [ word for word in complete if word.isdigit() ]
    return numbers

Where is web.xml in Eclipse Dynamic Web Project

Follow below steps to generate web.xml in Eclipse with existing Dynamic Web Project

  1. Right Click on Created Dynamic Web Project
  2. Mouse Over Java EE Tools
  3. Click on Generate Deployment Descriptor Stub
  4. Now you are able to see web.xml file on WEB-INF folder

enter image description here

Error related to only_full_group_by when executing a query in MySql

Use ANY_VALUE() to refer to the nonaggregated column.

SELECT name,           address , MAX(age) FROM t GROUP BY name; -- fails
SELECT name, ANY_VALUE(address), MAX(age) FROM t GROUP BY name; -- works

From MySQL 5.7 docs:

You can achieve the same effect without disabling ONLY_FULL_GROUP_BY by using ANY_VALUE() to refer to the nonaggregated column.


This query might be invalid with ONLY_FULL_GROUP_BY enabled because the nonaggregated address column in the select list is not named in the GROUP BY clause:

SELECT name, address, MAX(age) FROM t GROUP BY name;


If you know that, for a given data set, each name value in fact uniquely determines the address value, address is effectively functionally dependent on name. To tell MySQL to accept the query, you can use the ANY_VALUE() function:

SELECT name, ANY_VALUE(address), MAX(age) FROM t GROUP BY name;

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

If you've opened a table and you want to clear an existing value to NULL, click on the value, and press Ctrl+0.

Matplotlib tight_layout() doesn't take into account figure suptitle

Tight layout doesn't work with suptitle, but constrained_layout does. See this question Improve subplot size/spacing with many subplots in matplotlib

I found adding the subplots at once looked better, i.e.

fig, axs = plt.subplots(rows, cols, constrained_layout=True)

# then iterating over the axes to fill in the plots

But it can also be added at the point the figure is created:

fig = plt.figure(constrained_layout=True)

ax1 = fig.add_subplot(cols, rows, 1)
# etc

Note: To make my subplots closer together, I was also using


and constrained_layout doesn't work with this :(

How do I get the SQLSRV extension to work with PHP, since MSSQL is deprecated?


The MSSQL extension is not available anymore on Windows with PHP 5.3 or later. SQLSRV, an alternative driver for MS SQL is available from Microsoft: »

Once you downloaded that, follow the instructions at this page:

In a nutshell:

Put the driver file in your PHP extension directory.
Modify the php.ini file to include the driver. For example:


Restart the Web server.

See Also (copied from that page)

The PHP Manual for the SQLSRV extension is located at and offers the following for Installation:

The SQLSRV extension is enabled by adding appropriate DLL file to your PHP extension directory and the corresponding entry to the php.ini file. The SQLSRV download comes with several driver files. Which driver file you use will depend on 3 factors: the PHP version you are using, whether you are using thread-safe or non-thread-safe PHP, and whether your PHP installation was compiled with the VC6 or VC9 compiler. For example, if you are running PHP 5.3, you are using non-thread-safe PHP, and your PHP installation was compiled with the VC9 compiler, you should use the php_sqlsrv_53_nts_vc9.dll file. (You should use a non-thread-safe version compiled with the VC9 compiler if you are using IIS as your web server). If you are running PHP 5.2, you are using thread-safe PHP, and your PHP installation was compiled with the VC6 compiler, you should use the php_sqlsrv_52_ts_vc6.dll file.

The drivers can also be used with PDO.

How to make a back-to-top button using CSS and HTML only?

Utilize the <a> tag.

At the top of your website, put an anchor with specified name.

<a name="top"></a>

Then your "back to top" link points to it.

<a href="#top">back to top</a>

HTML Best Practices: Should I use &rsquo; or the special keyboard shortcut?

Typographically, the correct glyph to use in sentence punctuation is the quote mark, both single (including for apostrophes) and double quotes. The straight-looking mark that we often see on the web is called a prime, which also comes in single and double varieties and has limited uses, mostly for measurements.

This article explains how to use them correctly.

How can I switch my git repository to a particular commit

All the above commands create a new branch and with the latest commit being the one specified in the command, but just in case you want your current branch HEAD to move to the specified commit, below is the command:

 git checkout <commit_hash>

It detaches and point the HEAD to specified commit and saves from creating a new branch when the user just wants to view the branch state till that particular commit.

You then might want to go back to the latest commit & fix the detached HEAD:

Fix a Git detached head?

How to write a test which expects an Error to be thrown in Jasmine?

A more elegant solution than creating an anonymous function who's sole purpose is to wrap another, is to use es5's bind function. The bind function creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.

Instead of:

expect(function () { parser.parse(raw, config); } ).toThrow("Parsing is not possible");


expect(parser.parse.bind(parser, raw, config)).toThrow("Parsing is not possible");

The bind syntax allows you to test functions with different this values, and in my opinion makes the test more readable. See also:

Allowed memory size of X bytes exhausted

ini_set('memory_limit', '128M'); 


php.ini  =>  memory_limit = 128M


php_value memory_limit 128M

Convert string to Date in java

SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
String dateInString = "07/06/2013";

try {

    Date date = formatter.parse(dateInString);

} catch (ParseException e) {


2014/08/06 16:06:54
2014/08/06 16:06:54

Ansible: Set variable to file content

You can use the slurp module to fetch a file from the remote host: (Thanks to @mlissner for suggesting it)

  amazon_linux_ami: "ami-fb8e9292"
  user_data_file: ""
- name: Load data
    src: "{{ user_data_file }}"
  register: slurped_user_data
- name: Decode data and store as fact # You can skip this if you want to use the right hand side directly...
    user_data: "{{ slurped_user_data.content | b64decode }}"

Can I configure a subdomain to point to a specific port on my server

If you have access to SRV Records, you can use them to get what you want :)


A Records

Value: <yourIP>

Value: <yourIP>

SRV Records

Priority: 5
Weight: 5
Port: 25565

Priority: 5
Weight: 5
Port: 25566

then in minecraft you can use which will sign you into server 1 using port 25565

and which will sign you into server 2 using port 25566

then on your router you can have it point 25565 and 25566 to the machine with both servers on and Voilà!

Source: This works for me running 2 minecraft servers on the same machine with ports 50500 and 50501

Bootstrap tab activation with JQuery

why not select active tab first then active the selected tab content ?
1. Add class 'active' to the < li > element of tab first .
2. then use set 'active' class to selected div.

    $(document).ready( function(){
        SelectTab(1); //or use other method  to set active class to tab

    function SelectTab(tabindex)
        $('.nav-tabs li ').removeClass('active');
        $('.nav-tabs li').eq(tabindex).addClass('active'); 
        //tabindex start at 0 
    function FindActiveDiv()
        var DivName = $('.nav-tabs .active a').attr('href');  
        return DivName;
    function RemoveFocusNonActive()
        $('.nav-tabs  a').not('.active').blur();  
        //to >  remove  :hover :focus;
    function ShowInitialTabContent()
        var DivName = FindActiveDiv();
        if (DivName)

Access Tomcat Manager App from different host

To access the tomcat manager from different machine you have to follow bellow steps:

1. Update conf/tomcat-users.xml file with user and some roles:

<role rolename="manager-gui"/>
 <role rolename="manager-script"/>
 <role rolename="manager-jmx"/>
 <role rolename="manager-status"/>
 <user username="admin" password="admin" roles="manager-gui,manager-script,manager-jmx,manager-status"/>

Here admin user is assigning roles="manager-gui,manager-script,manager-jmx,manager-status".

Here tomcat user and password is : admin

2. Update webapps/manager/META-INF/context.xml file (Allowing IP address):

Default configuration:

<Context antiResourceLocking="false" privileged="true" >
  <Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
  <Manager sessionAttributeValueClassNameFilter="java\.lang\.(?:Boolean|Integer|Long|Number|String)|org\.apache\.catalina\.filters\.CsrfPreventionFilter\$LruCache(?:\$1)?|java\.util\.(?:Linked)?HashMap"/>

Here in Valve it is allowing only local machine IP start with 127.\d+.\d+.\d+ .

2.a : Allow specefic IP:

<Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1|YOUR.IP.ADDRESS.HERE" />

Here you just replace |YOUR.IP.ADDRESS.HERE with your IP address

2.b : Allow all IP:

<Valve className="org.apache.catalina.valves.RemoteAddrValve"
         allow=".*" />

Here using allow=".*" you are allowing all IP.

Thanks :)

how to add script src inside a View when using Layout

You can add the script tags like how we use in the while doing client side validations like below.

    ViewBag.Title = "Index";

<script type="text/javascript" src="~/Scripts/jquery-3.1.1.min.js"></script>
<script type="text/javascript">
    $(function () {
       //Your code

Count the number of Occurrences of a Word in a String

StringUtils in apache commons-lang have CountMatches method to counts the number of occurrences of one String in another.

   String input = "i have a male cat. the color of male cat is Black";
   int occurance = StringUtils.countMatches(input, "male cat");

how to rotate text left 90 degree and cell size is adjusted according to text in html

Daniel Imms answer is excellent in regards to applying your CSS rotation to an inner element. However, it is possible to accomplish the end goal in a way that does not require JavaScript and works with longer strings of text.

Typically the whole reason to have vertical text in the first table column is to fit a long line of text in a short horizontal space and to go alongside tall rows of content (as in your example) or multiple rows of content (which I'll use in this example).

enter image description here

By using the ".rotate" class on the parent TD tag, we can not only rotate the inner DIV, but we can also set a few CSS properties on the parent TD tag that will force all of the text to stay on one line and keep the width to 1.5em. Then we can use some negative margins on the inner DIV to make sure that it centers nicely.

td {_x000D_
    border: 1px black solid;_x000D_
    padding: 5px;_x000D_
.rotate {_x000D_
  text-align: center;_x000D_
  white-space: nowrap;_x000D_
  vertical-align: middle;_x000D_
  width: 1.5em;_x000D_
.rotate div {_x000D_
     -moz-transform: rotate(-90.0deg);  /* FF3.5+ */_x000D_
       -o-transform: rotate(-90.0deg);  /* Opera 10.5 */_x000D_
  -webkit-transform: rotate(-90.0deg);  /* Saf3.1+, Chrome */_x000D_
             filter:  progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083);  /* IE6,IE7 */_x000D_
         -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=0.083)"; /* IE8 */_x000D_
         margin-left: -10em;_x000D_
         margin-right: -10em;_x000D_
<table cellpadding="0" cellspacing="0" align="center">_x000D_
        <td class='rotate' rowspan="4"><div>10 kilograms</div></td>_x000D_
        <td class='rotate' rowspan="4"><div>20 kilograms</div></td>_x000D_
        <td class='rotate' rowspan="4"><div>30 kilograms</div></td>_x000D_

One thing to keep in mind with this solution is that it does not work well if the height of the row (or spanned rows) is shorter than the vertical text in the first column. It works best if you're spanning multiple rows or you have a lot of content creating tall rows.

Have fun playing around with this on jsFiddle.

Select distinct rows from datatable in Linq

Dim distinctValues As List(Of Double) = (From r In _
DirectCast(DataTable.AsEnumerable(),IEnumerable(Of DataRow)) Where (Not r.IsNull("ColName")) _
Select r.Field(Of Double)("ColName")).Distinct().ToList()

Getting time elapsed in Objective-C

For anybody coming here looking for a getTickCount() implementation for iOS, here is mine after putting various sources together.

Previously I had a bug in this code (I divided by 1000000 first) which was causing some quantisation of the output on my iPhone 6 (perhaps this was not an issue on iPhone 4/etc or I just never noticed it). Note that by not performing that division first, there is some risk of overflow if the numerator of the timebase is quite large. If anybody is curious, there is a link with much more information here:

In light of that information, maybe it is safer to use Apple's function CACurrentMediaTime!

I also benchmarked the mach_timebase_info call and it takes approximately 19ns on my iPhone 6, so I removed the (not threadsafe) code which was caching the output of that call.

#include <mach/mach.h>
#include <mach/mach_time.h>

uint64_t getTickCount(void)
    mach_timebase_info_data_t sTimebaseInfo;
    uint64_t machTime = mach_absolute_time();

    // Convert to milliseconds
    machTime *= sTimebaseInfo.numer;
    machTime /= sTimebaseInfo.denom;
    machTime /= 1000000; // convert from nanoseconds to milliseconds

    return machTime;

Do be aware of the potential risk of overflow depending on the output of the timebase call. I suspect (but do not know) that it might be a constant for each model of iPhone. on my iPhone 6 it was 125/3.

The solution using CACurrentMediaTime() is quite trivial:

uint64_t getTickCount(void)
    double ret = CACurrentMediaTime();
    return ret * 1000;

What does upstream mean in nginx?

upstream defines a cluster that you can proxy requests to. It's commonly used for defining either a web server cluster for load balancing, or an app server cluster for routing / load balancing.

adb doesn't show nexus 5 device

Follow these steps,

  • Enable Developer options in your device. To enable the developer mode, Settings->About phone, tap Build number option 7 times continuously
  • Go to Settings-> Developer options and Turn on USB debugging
  • Make sure you reconnected the device via USB and grant permission on the dialog that appears.
  • From the above steps it didn't work try this step, Go to Settings->Security and turn on Unknown Sources

How to resize a custom view programmatically?

If you have only two or three condition(sizes) then you can use @Overide onMeasure like

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

And change your size for these conditions in CustomView class easily.

How to remove foreign key constraint in sql server?

If you find yourself in a situation where the FK name of a table has been auto-generated and you aren't able to view what it exactly is (in the case of not having rights to a database for instance) you could try something like this:

SELECT @table = N'dbo.Table';
SELECT @sql = 'ALTER TABLE ' + @table
    + ' DROP CONSTRAINT ' + NAME + ';'
    FROM sys.foreign_keys
    WHERE [type] = 'F'
    AND [parent_object_id] = OBJECT_ID(@table);
EXEC sp_executeSQL @sql;

Build up a stored proc which drops the constraint of the specified table without specifying the actual FK name. It drops the constraint where the object [type] is equal to F (Foreign Key constraint).

Note: if there are multiple FK's in the table it will drop them all. So this solution works best if the table you are targeting has just one FK.

MySQL Data - Best way to implement paging?

Query 1: SELECT * FROM yourtable WHERE id > 0 ORDER BY id LIMIT 500

Query 2: SELECT * FROM tbl LIMIT 0,500;

Query 1 run faster with small or medium records, if number of records equal 5,000 or higher, the result are similar.

Result for 500 records:

Query1 take 9.9999904632568 milliseconds

Query2 take 19.999980926514 milliseconds

Result for 8,000 records:

Query1 take 129.99987602234 milliseconds

Query2 take 160.00008583069 milliseconds

How do I remove the last comma from a string using PHP?

Try the below code:

$my_string = "'name', 'name2', 'name3',";
echo substr(trim($my_string), 0, -1);

Use this code to remove the last character of the string.

OS specific instructions in CMAKE: How to?

Try that:


target_link_libraries(${PROJECT_NAME} bioutils ${ADDITIONAL_LIBRARIES})

You can find other useful variables here.

Django 1.7 - makemigrations not detecting changes

I had the same problem with having to run makemigrations twice and all sorts of strange behaviour. It turned out the root of the problem was that I was using a function to set default dates in my models so migrations was detecting a change every time I ran makemigrations. The answer to this question put me on the right track: Avoid makemigrations to re-create date field

What's the difference between deadlock and livelock?

I just planned to share some knowledge.

Deadlocks A set of threads/processes is deadlocked, if each thread/process in the set is waiting for an event that only another process in the set can cause.

The important thing here is another process is also in the same set. that means another process also blocked and no one can proceed.

Deadlocks occur when processes are granted exclusive access to resources.

These four conditions should be satisfied to have a deadlock.

  1. Mutual exclusion condition (Each resource is assigned to 1 process)
  2. Hold and wait condition (Process holding resources and at the same time it can ask other resources).
  3. No preemption condition (Previously granted resources can not forcibly be taken away) #This condition depends on the application
  4. Circular wait condition (Must be a circular chain of 2 or more processes and each is waiting for resource held by the next member of the chain) # It will happen dynamically

If we found these conditions then we can say there may be occurred a situation like a deadlock.


Each thread/process is repeating the same state again and again but doesn't progress further. Something similar to a deadlock since the process can not enter the critical section. However in a deadlock, processes are wait without doing anything but in livelock, the processes are trying to proceed but processes are repeated to the same state again and again.

(In a deadlocked computation there is no possible execution sequence which succeeds. but In a livelocked computation, there are successful computations, but there are one or more execution sequences in which no process enters its critical section.)

Difference from deadlock and livelock

When deadlock happens, No execution will happen. but in livelock, some executions will happen but those executions are not enough to enter the critical section.

Select the top N values by group

# start with the mtcars data frame (included with your installation of R)

# pick your 'group by' variable
gbv <- 'cyl'
# IMPORTANT NOTE: you can only include one group by variable here
# ..if you need more, the `order` function below will need
# one per inputted parameter: order( x$cyl , x$am )

# choose whether you want to find the minimum or maximum
find.maximum <- FALSE

# create a simple data frame with only two columns
x <- mtcars

# order it based on 
x <- x[ order( x[ , gbv ] , decreasing = find.maximum ) , ]

# figure out the ranks of each miles-per-gallon, within cyl columns
if ( find.maximum ){
    # note the negative sign (which changes the order of mpg)
    # *and* the `rev` function, which flips the order of the `tapply` result
    x$ranks <- unlist( rev( tapply( -x$mpg , x[ , gbv ] , rank ) ) )
} else {
    x$ranks <- unlist( tapply( x$mpg , x[ , gbv ] , rank ) )
# now just subset it based on the rank column
result <- x[ x$ranks <= 3 , ]

# look at your results

# done!

# but note only *two* values where cyl == 4 were kept,
# because there was a tie for third smallest, and the `rank` function gave both '3.5'
x[ x$ranks == 3.5 , ]

# ..if you instead wanted to keep all ties, you could change the
# tie-breaking behavior of the `rank` function.
# using the `min` *includes* all ties.  using `max` would *exclude* all ties
if ( find.maximum ){
    # note the negative sign (which changes the order of mpg)
    # *and* the `rev` function, which flips the order of the `tapply` result
    x$ranks <- unlist( rev( tapply( -x$mpg , x[ , gbv ] , rank , ties.method = 'min' ) ) )
} else {
    x$ranks <- unlist( tapply( x$mpg , x[ , gbv ] , rank , ties.method = 'min' ) )
# and there are even more options..
# see ?rank for more methods

# now just subset it based on the rank column
result <- x[ x$ranks <= 3 , ]

# look at your results
# and notice *both* cyl == 4 and ranks == 3 were included in your results
# because of the tie-breaking behavior chosen.

Digital Certificate: How to import .cer file in to .truststore file using?

# Copy the certificate into the directory Java_home\Jre\Lib\Security
# Change your directory to Java_home\Jre\Lib\Security>
# Import the certificate to a trust store.

keytool -import -alias ca -file somecert.cer -keystore cacerts -storepass changeit [Return]

Trust this certificate: [Yes]

changeit is the default truststore password

Why should hash functions use a prime number modulus?

I'd like to add something for Steve Jessop's answer(I can't comment on it since I don't have enough reputation). But I found some helpful material. His answer is very help but he made a mistake: the bucket size should not be a power of 2. I'll just quote from the book "Introduction to Algorithm" by Thomas Cormen, Charles Leisersen, et al on page263:

When using the division method, we usually avoid certain values of m. For example, m should not be a power of 2, since if m = 2^p, then h(k) is just the p lowest-order bits of k. Unless we know that all low-order p-bit patterns are equally likely, we are better off designing the hash function to depend on all the bits of the key. As Exercise 11.3-3 asks you to show, choosing m = 2^p-1 when k is a character string interpreted in radix 2^p may be a poor choice, because permuting the characters of k does not change its hash value.

Hope it helps.

How to Run a jQuery or JavaScript Before Page Start to Load

Hide the body with css then show it after the page is loaded:


html { visibility:hidden; }


$(document).ready(function() {
  document.getElementsByTagName("html")[0].style.visibility = "visible";

The page will go from blank to showing all content when the page is loaded, no flash of content, no watching images load etc.

setting content between div tags using javascript

If the number of your messages is limited then the following may help. I used jQuery for the following example, but it works with plain js too.

The innerHtml property did not work for me. So I experimented with ...

    <div id=successAndErrorMessages-1>100% OK</div>
    <div id=successAndErrorMessages-2>This is an error mssg!</div>

and toggled one of the two on/off ...

 $("#successAndErrorMessages-1").css('display', 'none')
 $("#successAndErrorMessages-2").css('display', '')

For some reason I had to fiddle around with the ordering before it worked in all types of browsers.

Best practice for localization and globalization of strings and labels

As far as I know, there's a good library called localeplanet for Localization and Internationalization in JavaScript. Furthermore, I think it's native and has no dependencies to other libraries (e.g. jQuery)

Here's the website of library:

Also look at this article by Mozilla, you can find very good method and algorithms for client-side translation:

The common part of all those articles/libraries is that they use a i18n class and a get method (in some ways also defining an smaller function name like _) for retrieving/converting the key to the value. In my explaining the key means that string you want to translate and the value means translated string.
Then, you just need a JSON document to store key's and value's.

For example:

var _ = document.webL10n.get;

And here the JSON:

{ test: "blah blah" }

I believe using current popular libraries solutions is a good approach.

Get exception description and stack trace which caused an exception, all as a string

If your goal is to make the exception and stacktrace message look exactly like when python throws an error, the following works in both python 2+3:

import sys, traceback

def format_stacktrace():
    parts = ["Traceback (most recent call last):\n"]
    return "".join(parts)


def a():

def b():

def c():

def d():
    assert False, "Noooh don't do it."


    stacktrace = format_stacktrace()


It works by removing the last format_stacktrace() call from the stack and joining the rest. When run, the example above gives the following output:


Traceback (most recent call last):
  File "", line 31, in <module>
  File "", line 12, in a
  File "", line 16, in b
  File "", line 20, in c
  File "", line 24, in d
    assert False, "Noooh don't do it."
AssertionError: Noooh don't do it.


Traceback (most recent call last):
  File "", line 38, in <module>
  File "", line 12, in a
  File "", line 16, in b
  File "", line 20, in c
  File "", line 24, in d
    assert False, "Noooh don't do it."
AssertionError: Noooh don't do it.

C++ wait for user input

Several ways to do so, here are some possible one-line approaches:

  1. Use getch() (need #include <conio.h>).

  2. Use getchar() (expected for Enter, need #include <iostream>).

  3. Use cin.get() (expected for Enter, need #include <iostream>).

  4. Use system("pause") (need #include <iostream>).

    PS: This method will also print Press any key to continue . . . on the screen. (seems perfect choice for you :))

Edit: As discussed here, There is no completely portable solution for this. Question 19.1 of the comp.lang.c FAQ covers this in some depth, with solutions for Windows, Unix-like systems, and even MS-DOS and VMS.

Import CSV to SQLite

before .import command, type ".mode csv"

Line break in SSRS expression

It wasn't working for me either. vbcrlf and Environment.Newline() both had no effect. My problem was that the Placeholder Properties had a Markup type of HTML. When I changed it to None, it worked like a champ!

How to get Linux console window width in Python

Many of the Python 2 implementations here will fail if there is no controlling terminal when you call this script. You can check sys.stdout.isatty() to determine if this is in fact a terminal, but that will exclude a bunch of cases, so I believe the most pythonic way to figure out the terminal size is to use the builtin curses package.

import curses
w = curses.initscr()
height, width = w.getmaxyx()

AngularJS: How to set a variable inside of a template?

It's not the best answer, but its also an option: since you can concatenate multiple expressions, but just the last one is rendered, you can finish your expression with "" and your variable will be hidden.

So, you could define the variable with:

{{f = forecast[day.iso]; ""}}

excel - if cell is not blank, then do IF statement

You need to use AND statement in your formula


And if both conditions are met, return 1.

You could also add more conditions in your AND statement.

How to verify if $_GET exists?

You can use isset function:

if(isset($_GET['id'])) {
    // id index exists

You can create a handy function to return default value if index doesn't exist:

function Get($index, $defaultValue) {
    return isset($_GET[$index]) ? $_GET[$index] : $defaultValue;

// prints "invalid id" if $_GET['id'] is not set
echo Get('id', 'invalid id');

You can also try to validate it at the same time:

function GetInt($index, $defaultValue) {
    return isset($_GET[$index]) && ctype_digit($_GET[$index])
            ? (int)$_GET[$index] 
            : $defaultValue;

// prints 0 if $_GET['id'] is not set or is not numeric
echo GetInt('id', 0);

Network usage top/htop on Linux

NetHogs is probably what you're looking for:

a small 'net top' tool. Instead of breaking the traffic down per protocol or per subnet, like most tools do, it groups bandwidth by process.

NetHogs does not rely on a special kernel module to be loaded. If there's suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this. This makes it easy to identify programs that have gone wild and are suddenly taking up your bandwidth.

Since NetHogs heavily relies on /proc, most features are only available on Linux. NetHogs can be built on Mac OS X and FreeBSD, but it will only show connections, not processes...

Minimum Hardware requirements for Android development

Hey, I have used the same software on an AMD 3Ghz chip, dual core. had 2gbs of ram at the time, and i noticed the emulator ran at an alright speed, but took a ridiculous amount of time to load. I have not done enough development on Android to tell you if this is a common, or even still existing problem, but it is certainly something I remember from my experience.

How do I print to the debug output window in a Win32 app?

If you need to see the output of an existing program that extensively used printf w/o changing the code (or with minimal changes) you can redefine printf as follows and add it to the common header (stdafx.h).

int print_log(const char* format, ...)
    static char s_printf_buf[1024];
    va_list args;
    va_start(args, format);
    _vsnprintf(s_printf_buf, sizeof(s_printf_buf), format, args);
    return 0;

#define printf(format, ...) \
        print_log(format, __VA_ARGS__)

pandas get column average/mean

If you only want the mean of the weight column, select the column (which is a Series) and call .mean():

In [479]: df
         ID  birthyear    weight
0    619040       1962  0.123123
1    600161       1963  0.981742
2  25602033       1963  1.312312
3    624870       1987  0.942120

In [480]: df["weight"].mean()
Out[480]: 0.83982437500000007

How to remove an id attribute from a div using jQuery?

The capitalization is wrong, and you have an extra argument.

Do this instead:


For future reference, there aren't any jQuery methods that begin with a capital letter. They all take the same form as this one, starting with a lower case, and the first letter of each joined "word" is upper case.