Programs & Examples On #Minimax

A concept used in artificial intelligence/game theory for two-player games. The idea is to minimize the opponent's gain and maximize yours. Questions using this tag cover problems understanding/implementing the algorithm.

Getting the index of the returned max or min item using max()/min() on a list

Use a numpy array and the argmax() function

 print(b) #2

How do I get information about an index and table owner in Oracle?

The following may help give you want you need:

    index_owner, index_name, table_name, column_name, column_position

For my use case, I wanted the column_names and order that they are in the indices (so that I could recreate them in a different database engine after migrating to AWS). The following was what I used, in case it is of use to anyone else:

    index_name, table_name, column_name, column_position

How to initailize byte array of 100 bytes in java with all 0's

Simply create it as new byte[100] it will be initialized with 0 by default

How can I set focus on an element in an HTML form using JavaScript?

I used to just use this:

    <script type="text/javascript">
      function focusFieldOne() {

  <body onLoad="focusFieldOne();">
    <form name="FormName">
      Field <input type="text" name="FieldName">

That said, you can just use the autofocus attribute in HTML 5.

Please note: I wanted to update this old thread showing the example asked plus the newer, easier update for those still reading this. ;)

SQL Server: Cannot insert an explicit value into a timestamp column

According to MSDN, timestamp

Is a data type that exposes automatically generated, unique binary numbers within a database. timestamp is generally used as a mechanism for version-stamping table rows. The storage size is 8 bytes. The timestamp data type is just an incrementing number and does not preserve a date or a time. To record a date or time, use a datetime data type.

You're probably looking for the datetime data type instead.

Scroll RecyclerView to show selected item on top

what i did to restore the scroll position after refreshing the RecyclerView on button clicked:

if (linearLayoutManager != null) {

    index = linearLayoutManager.findFirstVisibleItemPosition();
    View v = linearLayoutManager.getChildAt(0);
    top = (v == null) ? 0 : (v.getTop() - linearLayoutManager.getPaddingTop());
    Log.d("TAG", "visible position " + " " + index);

    index = 0;

linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.scrollToPositionWithOffset(index, top);

getting the offset of the first visible item from the top before creating the linearLayoutManager object and after instantiating it the scrollToPositionWithOffset of the LinearLayoutManager object was called.

How to get `DOM Element` in Angular 2?

Angular 2.0.0 Final:

I have found that using a ViewChild setter is most reliable way to set the initial form control focus:

set myInput(_input: ElementRef | undefined) {
    if (_input !== undefined) {
        setTimeout(() => {
            this._renderer.invokeElementMethod(_input.nativeElement, "focus");
        }, 0);

The setter is first called with an undefined value followed by a call with an initialized ElementRef.

Working example and full source here:

Using TypeScript 2.0.3 Final/RTM, Angular 2.0.0 Final/RTM, and Chrome 53.0.2785.116 m (64-bit).

UPDATE for Angular 4+

Renderer has been deprecated in favor of Renderer2, but Renderer2 does not have the invokeElementMethod. You will need to access the DOM directly to set the focus as in input.nativeElement.focus().

I'm still finding that the ViewChild setter approach works best. When using AfterViewInit I sometimes get read property 'nativeElement' of undefined error.

set myInput(_input: ElementRef | undefined) {
    if (_input !== undefined) {
        setTimeout(() => { //This setTimeout call may not be necessary anymore.
        }, 0);

Interactive shell using Docker Compose

This question is very interesting for me because I have problems, when I run container after execution finishes immediately exit and I fixed with -it:

docker run -it -p 3000:3000 -v /app/node_modules -v $(pwd):/app <your_container_id>

And when I must automate it with docker compose:

version: '3'
        stdin_open: true
        tty: true
            context: .
            - "3000:3000"
            - /app/node_modules
            - .:/app

This makes the trick: stdin_open: true, tty: true

This is a project generated with create-react-app it looks this that:

FROM node:alpine

WORKDIR '/app'

COPY package.json .
RUN npm install

COPY . . 

CMD ["npm", "run", "start"]

Hope this example will help other to run a frontend(react in example) into docker container.


SELECT  p.LastName, p.FirstName, o.OrderNo
FROM    persons AS p
        orders AS o
ON      o.orderNo = p.p_id
FROM    orders
WHERE   orderNo NOT IN
        SELECT  p_id
        FROM    persons

Oracle SQL convert date format from DD-Mon-YY to YYYYMM

Am I missing something? You can just convert offer_date in the comparison:

FROM offers
WHERE to_char(offer_date, 'YYYYMM') = (SELECT to_date(create_date, 'YYYYMM') FROM customers where id = '12345678') AND
      offer_rate > 0 

How to save python screen output to a text file

A quick and dirty hack to do this within the script is to direct the screen output to a file:

import sys 

sys.stdout = open("log.txt", "w")

and then reverting back to outputting to screen at the end of your code:


This should work for a simple code, but for a complex code there are other more formal ways of doing it such as using Python logging.

How to check if a MySQL query using the legacy API was successful?

You can use mysql_errno() for this too.

$result = mysql_query($query);

    echo "MySQL error ".mysql_errno().": "
         .mysql_error()."\n<br>When executing <br>\n$query\n<br>";

Android Studio Rendering Problems : The following classes could not be found

To use the class ActionBarOverlayLayout you need to include this in the dependencies section of build.gradle file:

compile ''

Sync the project once again and then you will find no problem

Android Push Notifications: Icon not displaying in notification, white square shown instead

 <meta-data android:name=""

        android:resource="@drawable/ic_notification" />

add this line in the manifest.xml file in application block

HashMap - getting First Key value

Note that you should note that your logic flow must never rely on accessing the HashMap elements in some order, simply put because HashMaps are not ordered Collections and that is not what they are aimed to do. (You can read more about odered and sorter collections in this post).

Back to the post, you already did half the job by loading the first element key:

Object myKey = statusName.keySet().toArray()[0];

Just call map.get(key) to get the respective value:

Object myValue = statusName.get(myKey);

How to solve 'Redirect has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header'?

If you have control over your server, you can use PHP:

header('Access-Control-Allow-Origin: *');

How can I hide a TD tag using inline JavaScript or CSS?

You can simply hide the <td> tag content by just including a style attribute: style = "display:none"

For e.g

<td style = "display:none" >
<p> I'm invisible </p>

Insert into C# with SQLCommand

public class customer
    public void InsertCustomer(string name,int age,string address)
        // create and open a connection object
        using(SqlConnection Con=DbConnection.GetDbConnection())
            // 1. create a command object identifying the stored procedure
            SqlCommand cmd = new SqlCommand("spInsertCustomerData",Con);

            // 2. set the command object so it knows to execute a stored procedure
            cmd.CommandType = CommandType.StoredProcedure;

            SqlParameter paramName = new SqlParameter();
            paramName.ParameterName = "@nvcname";
            paramName.Value = name;

            SqlParameter paramAge = new SqlParameter();
            paramAge.ParameterName = "@inage";
            paramAge.Value = age;

            SqlParameter paramAddress = new SqlParameter();
            paramAddress.ParameterName = "@nvcaddress";
            paramAddress.Value = address;


ORA-01950: no privileges on tablespace 'USERS'

You cannot insert data because you have a quota of 0 on the tablespace. To fix this, run

ALTER USER <user> quota unlimited on <tablespace name>;


ALTER USER <user> quota 100M on <tablespace name>;

as a DBA user (depending on how much space you need / want to grant).

Add days Oracle SQL

In a more general way you can use "INTERVAL". Here some examples:

1) add a day

select sysdate + INTERVAL '1' DAY from dual;

2) add 20 days

select sysdate + INTERVAL '20' DAY from dual;

2) add some minutes

select sysdate + INTERVAL '15' MINUTE from dual;

Changing the JFrame title

these methods can help setTitle("your new title"); or super("your new title");

How to programmatically connect a client to a WCF service?

You'll have to use the ChannelFactory class.

Here's an example:

var myBinding = new BasicHttpBinding();
var myEndpoint = new EndpointAddress("http://localhost/myservice");
using (var myChannelFactory = new ChannelFactory<IMyService>(myBinding, myEndpoint))
    IMyService client = null;

        client = myChannelFactory.CreateChannel();
        (client as ICommunicationObject)?.Abort();

Related resources:

File upload progress bar with jQuery

This solved my problem

var url = "http://localhost/tech1/index.php?route=app/upload/ajax"; 

  xhr: function() {
    var xhr = new window.XMLHttpRequest();

    xhr.upload.addEventListener("progress", function(evt) {
      if (evt.lengthComputable) {
        var percentComplete = evt.loaded /;
        percentComplete = parseInt(percentComplete * 100);
var $link = $('.'+ids);
          var $img = $link.find('i'); 
    }, false);

    return xhr;
  url: url,
  type: "POST",
  data: JSON.stringify(uploaddata),
  contentType: "application/json",
  dataType: "json",
  success: function(result) {

How do you use String.substringWithRange? (or, how do Ranges work in Swift?)

NOTE: @airspeedswift makes some very insightful points on the trade-offs of this approach, particularly the hidden performance impacts. Strings are not simple beasts, and getting to a particular index may take O(n) time, which means a loop that uses a subscript can be O(n^2). You have been warned.

You just need to add a new subscript function that takes a range and uses advancedBy() to walk to where you want:

import Foundation

extension String {
    subscript (r: Range<Int>) -> String {
        get {
            let startIndex = self.startIndex.advancedBy(r.startIndex)
            let endIndex = startIndex.advancedBy(r.endIndex - r.startIndex)

            return self[Range(start: startIndex, end: endIndex)]

var s = "Hello, playground"

println(s[0...5]) // ==> "Hello,"
println(s[0..<5]) // ==> "Hello"

(This should definitely be part of the language. Please dupe rdar://17158813)

For fun, you can also add a + operator onto the indexes:

func +<T: ForwardIndex>(var index: T, var count: Int) -> T {
  for (; count > 0; --count) {
    index = index.succ()
  return index

s.substringWithRange(s.startIndex+2 .. s.startIndex+5)

(I don't know yet if this one should be part of the language or not.)

Export JAR with Netbeans

Do you mean compile it to JAR? NetBeans does that automatically, just do "clean and build" and look in the "dist" subdirectory of your project. There will be the JAR with "lib" folder containing the required libraries. These JAR + lib are enough to run the application.

If you disable "Compile on save" in the project properties, then it is no longer necessary to do "clean and build", simply "build" will suffice in most cases. This will save time if you want to change just a bit of the code and rebuild the JAR. However, note that NetBeans sometimes fails to handle dependencies and binary compatibility properly, which will lead to a faulty JAR throwing "no such method" or other obscure exceptions. Therefore, if you made a lot of changes since the last full rebuild and even remotely unsure that it will still work even if some classes aren't recompiled, then you must still do a full "clean and build" in order to get a perfectly working JAR.

Proxy Error 502 : The proxy server received an invalid response from an upstream server

Add this into your httpd.conf file

Timeout 2400
ProxyTimeout 2400
ProxyBadHeader Ignore 

What Does This Mean in PHP -> or =>


calls/sets object variables. Ex:

$obj = new StdClass;
$obj->foo = 'bar';

=> Sets key/value pairs for arrays. Ex:

$array = array(
    'foo' => 'bar'

Java method to sum any number of ints

You could do, assuming you have an array with value and array length: arrayVal[i], arrayLength:

int sum = 0;
for (int i = 0; i < arrayLength; i++) {
    sum += arrayVal[i];

System.out.println("the sum is" + sum);

I hope this helps.

How to iterate over array of objects in Handlebars?

Using this and {{this}}. See code below in node.js:

var Handlebars= require("handlebars");
var randomList= ["James Bond", "Dr. No", "Octopussy", "Goldeneye"];
var source= "<ul>{{#each this}}<li>{{this}}</li>{{/each}}</ul>";
var template= Handlebars.compile(source);

Console log output:

<ul><li>James Bond</li><li>Dr. No</li><li>Octopussy</li><li>Goldeneye</li></ul>

Can't bind to 'formControl' since it isn't a known property of 'input' - Angular2 Material Autocomplete issue

Another reason this can happen:

The component you are using formControl in is not declared in a module that imports the ReactiveFormsModule.

So check the module that declares the component that throws this error.

How do I create a constant in Python?

Here is an implementation of a "Constants" class, which creates instances with read-only (constant) attributes. E.g. can use Nums.PI to get a value that has been initialized as 3.14159, and Nums.PI = 22 raises an exception.

# ---------- ----------
class Constants(object):
    Create objects with read-only (constant) attributes.
        Nums = Constants(ONE=1, PI=3.14159, DefaultWidth=100.0)
        print 10 + Nums.PI
        print '----- Following line is deliberate ValueError -----'
        Nums.PI = 22

    def __init__(self, *args, **kwargs):
        self._d = dict(*args, **kwargs)

    def __iter__(self):
        return iter(self._d)

    def __len__(self):
        return len(self._d)

    # NOTE: This is only called if self lacks the attribute.
    # So it does not interfere with get of 'self._d', etc.
    def __getattr__(self, name):
        return self._d[name]

    # ASSUMES '_..' attribute is OK to set. Need this to initialize 'self._d', etc.
    #If use as keys, they won't be constant.
    def __setattr__(self, name, value):
        if (name[0] == '_'):
            super(Constants, self).__setattr__(name, value)
            raise ValueError("setattr while locked", self)

if (__name__ == "__main__"):
    # Usage example.
    Nums = Constants(ONE=1, PI=3.14159, DefaultWidth=100.0)
    print 10 + Nums.PI
    print '----- Following line is deliberate ValueError -----'
    Nums.PI = 22

Thanks to @MikeGraham 's FrozenDict, which I used as a starting point. Changed, so instead of Nums['ONE'] the usage syntax is Nums.ONE.

And thanks to @Raufio's answer, for idea to override __ setattr __.

Or for an implementation with more functionality, see @Hans_meine 's named_constants at GitHub

Java for loop multiple variables

Instead of this : for(int a = 0, b = 1; a<cards.length-1; b=a+1; a++;){

It should be

for(int a = 0, b = 1; a<cards.length()-1; b=a+1, a++){
                                     ^         ^    ^  
                                     |         |    |  
                                     |         |    |  
            -------------------------------------------Note the changes
           v                                                  |
   if(rank==cards.substring(a,b){                             |
System.out.println(c); //capital S in system

How to convert an object to JSON correctly in Angular 2 with TypeScript

Because you're encapsulating the product again. Try to convert it like so:

let body = JSON.stringify(product); 

Allow docker container to connect to a local/host postgres database


  1. Use as IP address range, not
  2. Don't use localhost to connect to the PostgreSQL database on your host, but the host's IP instead. To keep the container portable, start the container with the --add-host=database:<host-ip> flag and use database as hostname for connecting to PostgreSQL.
  3. Make sure PostgreSQL is configured to listen for connections on all IP addresses, not just on localhost. Look for the setting listen_addresses in PostgreSQL's configuration file, typically found in /etc/postgresql/9.3/main/postgresql.conf (credits to @DazmoNorton).

Long version is not a range of IP addresses, but a single address (namly No Docker container will ever get that address assigned, because it's the network address of the Docker bridge (docker0) interface.

When Docker starts, it will create a new bridge network interface, that you can easily see when calling ip a:

$ ip a
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 56:84:7a:fe:97:99 brd ff:ff:ff:ff:ff:ff
    inet scope global docker0
       valid_lft forever preferred_lft forever

As you can see, in my case, the docker0 interface has the IP address with a netmask of /16 (or This means that the network address is

The IP address is randomly assigned, but without any additional configuration, it will always be in the network. For each Docker container, a random address from that range will be assigned.

This means, if you want to grant access from all possible containers to your database, use

The following untracked working tree files would be overwritten by merge, but I don't care

The problem is that you are not tracking the files locally but identical files are tracked remotely so in order to "pull" your system would be forced to overwrite the local files which are not version controlled.

Try running

git add * 
git stash
git pull

This will track all files, remove all of your local changes to those files, and then get the files from the server.

Any way to write a Windows .bat file to kill processes?

You can do this with 'taskkill'. With the /IM parameter, you can specify image names.


taskkill /im somecorporateprocess.exe

You can also do this to 'force' kill:


taskkill /f /im somecorporateprocess.exe

Just add one line per process you want to kill, save it as a .bat file, and add in your startup directory. Problem solved!

If this is a legacy system, PsKill will do the same.

Rendering an in React

let durationBody =, i) => {
      return (
        <option key={i} value={item}>

C# Equivalent of SQL Server DataTypes

This is for SQL Server 2005. There are updated versions of the table for SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 and SQL Server 2014.

SQL Server Data Types and Their .NET Framework Equivalents

The following table lists Microsoft SQL Server data types, their equivalents in the common language runtime (CLR) for SQL Server in the System.Data.SqlTypes namespace, and their native CLR equivalents in the Microsoft .NET Framework.

SQL Server data type          CLR data type (SQL Server)    CLR data type (.NET Framework)  
varbinary                     SqlBytes, SqlBinary           Byte[]  
binary                        SqlBytes, SqlBinary           Byte[]  
varbinary(1), binary(1)       SqlBytes, SqlBinary           byte, Byte[] 
image                         None                          None

varchar                       None                          None
char                          None                          None
nvarchar(1), nchar(1)         SqlChars, SqlString           Char, String, Char[]     
nvarchar                      SqlChars, SqlString           String, Char[] 
nchar                         SqlChars, SqlString           String, Char[] 
text                          None                          None
ntext                         None                          None

uniqueidentifier              SqlGuid                       Guid 
rowversion                    None                          Byte[]  
bit                           SqlBoolean                    Boolean 
tinyint                       SqlByte                       Byte 
smallint                      SqlInt16                      Int16  
int                           SqlInt32                      Int32  
bigint                        SqlInt64                      Int64 

smallmoney                    SqlMoney                      Decimal  
money                         SqlMoney                      Decimal  
numeric                       SqlDecimal                    Decimal  
decimal                       SqlDecimal                    Decimal  
real                          SqlSingle                     Single  
float                         SqlDouble                     Double  

smalldatetime                 SqlDateTime                   DateTime  
datetime                      SqlDateTime                   DateTime 

sql_variant                   None                          Object  
User-defined type(UDT)        None                          user-defined type     
table                         None                          None 
cursor                        None                          None
timestamp                     None                          None 
xml                           SqlXml                        None

How do I free my port 80 on localhost Windows?

Type in "netstat -ano" into your command line. I saw that it was showing something for Local Address port

My issue was because I had SQL Server Reporting Services on Port 80. So I followed these instructions and changed the port # from 80 to 81:

Here is a picture of my command line AFTER I changed the port number for SQL Server Reporting Services:

enter image description here

If you are still having the same issue, read this forum:,66196,66233#REPLY

Scatter plot and Color mapping in Python

Subplot Colorbar

For subplots with scatter, you can trick a colorbar onto your axes by building the "mappable" with the help of a secondary figure and then adding it to your original plot.

As a continuation of the above example:

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(10)
y = x
t = x
fig, (ax1, ax2) = plt.subplots(1, 2)
ax1.scatter(x, y, c=t, cmap='viridis')
ax2.scatter(x, y, c=t, cmap='viridis_r')

# Build your secondary mirror axes:
fig2, (ax3, ax4) = plt.subplots(1, 2)

# Build maps that parallel the color-coded data
# NOTE 1: imshow requires a 2-D array as input
# NOTE 2: You must use the same cmap tag as above for it match
map1 = ax3.imshow(np.stack([t, t]),cmap='viridis')
map2 = ax4.imshow(np.stack([t, t]),cmap='viridis_r')

# Add your maps onto your original figure/axes
fig.colorbar(map1, ax=ax1)
fig.colorbar(map2, ax=ax2)

Scatter subplots with COLORBAR

Note that you will also output a secondary figure that you can ignore.

How do you run your own code alongside Tkinter's event loop?

The solution posted by Bjorn results in a "RuntimeError: Calling Tcl from different appartment" message on my computer (RedHat Enterprise 5, python 2.6.1). Bjorn might not have gotten this message, since, according to one place I checked, mishandling threading with Tkinter is unpredictable and platform-dependent.

The problem seems to be that app.start() counts as a reference to Tk, since app contains Tk elements. I fixed this by replacing app.start() with a self.start() inside __init__. I also made it so that all Tk references are either inside the function that calls mainloop() or are inside functions that are called by the function that calls mainloop() (this is apparently critical to avoid the "different apartment" error).

Finally, I added a protocol handler with a callback, since without this the program exits with an error when the Tk window is closed by the user.

The revised code is as follows:

# Run tkinter code in another thread

import tkinter as tk
import threading

class App(threading.Thread):

    def __init__(self):

    def callback(self):

    def run(self):
        self.root = tk.Tk()
        self.root.protocol("WM_DELETE_WINDOW", self.callback)

        label = tk.Label(self.root, text="Hello World")


app = App()
print('Now we can continue running code while mainloop runs!')

for i in range(100000):

Object not found! The requested URL was not found on this server. localhost

You are not specified your project as right way.

  • So run your XAMPP control panel then start the apache and MySQL
  • Then note the ports.
  • For Example PORT 80: then you type your browser url as localhost:80\ press enter now your php basic Config page is visible.
  • Then create any folder on xampp\htdocs\YourFloderName Then create php file then save it and go to browser then type it localhost\YourFolderName now it listed the files click the file and it runs.

Get scroll position using jquery

Older IE and Firefox browsers attach the scrollbar to the documentElement, or what would be the <html> tag in HTML.

All other browsers attach the scrollbar to document.body, or what would be the <body> tag in HTML.

The correct solution would be to check which one to use, depending on browser

var doc = document.documentElement.clientHeight ? document.documentElement : document.body;
var s   = $(doc).scrollTop();

jQuery does make this a little easier, when passing in either window or document jQuery's scrollTop does a similar check and figures it out, so either of these should work cross-browser

var s = $(document).scrollTop();


var s = $(window).scrollTop();

jQuery scrollTop() docs

Description: Get the current vertical position of the scroll bar for the first element in the set of matched elements or set the vertical position of the scroll bar for every matched element.

...nothing that works for my div, just the full page

If it's for a DIV, you'd have to target the element that has the scrollbar attached, to get the scrolled amount


If you need to get the elements distance from the top of the document, you can also do


macOS on VMware doesn't recognize iOS device

I met the same problem. I found the solution in the solution from
It works for me by adding

usb.quirks.device0 = "0xvid:0xpid skip-refresh"

Detail as below:

To add quirks:
  1. Shut down the virtual machine and quit Workstation/Fusion.

    Caution: Do not skip this step.
  2. Open the vmware.log file within the virtual machine bundle. For more information, see Locating a virtual machine bundle in VMware Workstation/Fusion (1007599).
  3. In the Filter box at the top of the Console window, enter the name of the device manufacturer.

    For example, if you enter the name Apple, you see a line that looks similar to:

    vmx | USB: Found device [name:Apple\ IR\ Receiver vid:05ac pid:8240 path:13/7/2 speed:full family:hid]

    The line has the name of the USB device and its vid and pid information. Make a note of the vid and pid values.

  4. Open the .vmx file using a text editor. For more information, see Editing the .vmx file for your Workstation/Fusion virtual machine (1014782).
  5. Add this line to the .vmx file, replacing vid and pid with the values noted in Step 2, each prefixed by the number 0 and the letter x .

    usb.quirks.device0 = "0xvid:0xpid skip-reset"

    For example, for the Apple device found in step 2, this line is:

    usb.quirks.device0 = "0x05ac:0x8240 skip-reset"

  6. Save the .vmx file.
  7. Re-open Workstation/Fusion. The edited .vmx file is reloaded with the changes.
  8. Start the virtual machine, and connect the device.
  9. If the issue is not resolved, replace the quirks line added in Step 4 with one of these lines, in the order provided, and repeat Steps 5 to 8:
usb.quirks.device0 = "0xvid:0xpid skip-refresh"
usb.quirks.device0 = "0xvid:0xpid skip-setconfig"
usb.quirks.device0 = "0xvid:0xpid skip-reset, skip-refresh, skip-setconfig"


  • Use one of these lines at a time. If one does not work, replace it with another one in the list. Do not add more than one of these in the .vmx file at a time.
  • The last line uses all three quirks in combination. Use this only if the other three lines do not work.

Refer this to see in detail.

Using quotation marks inside quotation marks

in Python 3.2.2 on Windows,

print(""""A word that needs quotation marks" """) 

is ok. I think it is the enhancement of Python interpretor.

Android: How do bluetooth UUIDs work?

The UUID is used for uniquely identifying information. It identifies a particular service provided by a Bluetooth device. The standard defines a basic BASE_UUID: 00000000-0000-1000-8000-00805F9B34FB.

Devices such as healthcare sensors can provide a service, substituting the first eight digits with a predefined code. For example, a device that offers an RFCOMM connection uses the short code: 0x0003

So, an Android phone can connect to a device and then use the Service Discovery Protocol (SDP) to find out what services it provides (UUID).

In many cases, you don't need to use these fixed UUIDs. In the case your are creating a chat application, for example, one Android phone interacts with another Android phone that uses the same application and hence the same UUID.

So, you can set an arbitrary UUID for your application using, for example, one of the many random UUID generators on the web (for example).

Class has no objects member

This issue happend when I use pylint_runner

So what I do is open .pylintrc file and add this

# List of members which are set dynamically and missed by pylint inference
# system, and so shouldn't trigger E1101 when accessed. Python regular
# expressions are accepted.

All combinations of a list of lists

Numpy can do it:

 >>> import numpy
 >>> a = [[1,2,3],[4,5,6],[7,8,9,10]]
 >>> [list(x) for x in numpy.array(numpy.meshgrid(*a)).T.reshape(-1,len(a))]
[[ 1, 4, 7], [1, 5, 7], [1, 6, 7], ....]

Filtering collections in C#

If you're using C# 3.0 you can use linq

Or, if you prefer, use the special query syntax provided by the C# 3 compiler:

var filteredList = from x in myList
                   where x > 7
                   select x;

Contain an image within a div?

#container img{

Video format or MIME type is not supported

For Ubuntu 14.04

Just removed the package Oxideqt-dodecs then install flash or ubuntu restricted extras

and you are good to go!!

Scanner is never closed

I am assuming you are using java 7, thus you get a compiler warning, when you don't close the resource you should close your scanner usually in a finally block.

Scanner scanner = null;
try {
    scanner = new Scanner(;
    //rest of the code
finally {

Or even better: use the new Try with resource statement:

try(Scanner scanner = new Scanner({
    //rest of your code

How do you exit from a void function in C++?

Use a return statement!



if (condition) return;

You don't need to (and can't) specify any values, if your method returns void.

How to deserialize JS date using Jackson?

In addition to Varun Achar's answer, this is the Java 8 variant I came up with, that uses java.time.LocalDate and ZonedDateTime instead of the old java.util.Date classes.

public class LocalDateDeserializer extends JsonDeserializer<LocalDate> {

    public LocalDate deserialize(JsonParser jsonparser, DeserializationContext deserializationcontext) throws IOException {

        String string = jsonparser.getText();

        if(string.length() > 20) {
            ZonedDateTime zonedDateTime = ZonedDateTime.parse(string);
            return zonedDateTime.toLocalDate();

        return LocalDate.parse(string);

How to get the Facebook user id using the access token

With the newest API, here's the code I used for it

NSDictionary *params = @{
                         @"access_token": [[FBSDKAccessToken currentAccessToken] tokenString],
                         @"fields": @"id"
/* make the API call */
FBSDKGraphRequest *request = [[FBSDKGraphRequest alloc]

[request startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection,
                                      id result,
                                      NSError *error) {
    NSDictionary *res = result;
    //res is a dict that has the key
    NSLog([res objectForKey:@"id"]);

Xcode 10 Error: Multiple commands produce

Moving to Xcode 10, errors like

error: Multiple commands produce '/Users/uesr/Library/Developer/Xcode/DerivedData/OptimalLive-fxatvygbofczeyhjsawtebkimvwx/Build/Products/Debug-iphoneos/':

can be solved as follows:

Go to Xcode->File->Workspace/Project Settings-> Build System -> Legacy Build System.

Select the first 10 rows - Laravel Eloquent

Another way to do it is using a limit method:


This can be useful if you're not trying to implement pagination, but for example, return 10 random rows from a table:


Get all child views inside LinearLayout at once

((ViewGroup) findViewById(;// you can use this in an Activity to get your layout root view, then pass it to findAllEdittexts() method below.

Here I am iterating only EdiTexts, if you want all Views you can replace EditText with View.

SparseArray<EditText> array = new SparseArray<EditText>();

private void findAllEdittexts(ViewGroup viewGroup) {

    int count = viewGroup.getChildCount();
    for (int i = 0; i < count; i++) {
        View view = viewGroup.getChildAt(i);
        if (view instanceof ViewGroup)
            findAllEdittexts((ViewGroup) view);
        else if (view instanceof EditText) {
            EditText edittext = (EditText) view;
            array.put(editText.getId(), editText);

Postgres FOR LOOP

Procedural elements like loops are not part of the SQL language and can only be used inside the body of a procedural language function, procedure (Postgres 11 or later) or a DO statement, where such additional elements are defined by the respective procedural language. The default is PL/pgSQL, but there are others.

Example with plpgsql:

   FOR i IN 1..25 LOOP
      INSERT INTO playtime.meta_random_sample
         (col_i, col_id)                       -- declare target columns!
      SELECT  i,     id
      FROM   tbl
      ORDER  BY random()
      LIMIT  15000;

For many tasks that can be solved with a loop, there is a shorter and faster set-based solution around the corner. Pure SQL equivalent for your example:

INSERT INTO playtime.meta_random_sample (col_i, col_id)
FROM   generate_series(1,25) i
   SELECT i, id
   FROM   tbl
   ORDER  BY random()
   LIMIT  15000
   ) t;

About generate_series():

About optimizing performance of random selections:

Generate a range of dates using SQL

Oracle specific, and doesn't rely on pre-existing large tables or complicated system views over data dictionary objects.

SELECT c1 from dual
  MODEL DIMENSION BY (1 as rn)  MEASURES (sysdate as c1)
order by 1

how to empty recyclebin through command prompt?


rd /s /q %systemdrive%\$RECYCLE.BIN

will delete the $RECYCLE.BIN folder from the system drive, which is usually c:, one should consider deleting it from any other available partitions since there's an hidden $RECYCLE.BIN folder in any partition in local and external drives (but not in removable drives, like USB flash drive, which don't have a $RECYCLE.BIN folder). For example, I installed a program in d:, in order to delete the files it moved to the Recycle Bin I should run:

rd /s /q d:\$RECYCLE.BIN

More information available at Super User at Empty recycling bin from command line

How to change onClick handler dynamically?

Nobody addressed the actual problem which was happening, to explain why the alert was issued.

This code: document.getElementById("foo").click = new function() { alert('foo'); }; assigns the click property of the #foo element to an empty object. The anonymous function in here is meant to initialize the object. I like to think of this type of function as a constructor. You put the alert in there, so it gets called because the function gets called immediately.

See this question.

Deprecated: mysql_connect()

Well, i just faced such message today when i moved to new hosting! anyway i have tried to change the "mySQL" to "mySQLi" but not working, so i have done this:

# FileName="Connection_php_mysql.htm"
# Type="MYSQL"
# HTTP="true"
# Turn off all error reporting
$connect_myconn = "Database Connection";
$hostname_myconn = "localhost";
$database_myconn = "db name";
$username_myconn = "user name";
$password_myconn = "pass";
$myconn = mysql_connect($hostname_myconn, $username_myconn, $password_myconn) or die("<h1 style=margin:0;>A MySQL error has occurred.</h1><p><b>Your Query:</b> " . $connect_myconn . "<br /> <b>Error Number:</b> (" . mysql_errno() . ")</p>" . mysql_error());
mysql_select_db($database_myconn, $myconn);

The trick is to set error reporting off :)

# Turn off all error reporting

For PHP 7+ you can use this code instead:

ini_set('display_errors', 0);
ini_set('log_errors', 1);


How to make a smaller RatingBar?

After a lot of research I found the best solution to reduce the size of custom rating bars is to get the size of progress drawable in certain sizes as mentioned below :

xxhdpi - 48*48 px

xhdpi - 36*36 px

hdpi - 24*24 px

And in style put the minheight and maxheight as 16 dp for all Resolution.

Let me know if this doesn't help you to get a best small size rating bars as these sizes I found very compatible and equivalent to ratingbar.small style attribute.

Ruby's gives "No such file or directory - text.txt (Errno::ENOENT)" error

Try using


To see what's in the directory (and therefore what directory it's looking at).

How to do an INNER JOIN on multiple columns

something like....

      , as from
      , as to
FROM flights f
INNER JOIN airports a1
ON f.fairport = a1. code
INNER JOIN airports a2
ON f.tairport = a2. code

Use '=' or LIKE to compare strings in SQL?

LIKE is used for pattern matching and = is used for equality test (as defined by the COLLATION in use).

= can use indexes while LIKE queries usually require testing every single record in the result set to filter it out (unless you are using full text search) so = has better performance.

How do I align a number like this in C?

Why is printf("%8d\n", intval); not working for you? It should...

You did not show the format strings for any of your "not working" examples, so I'm not sure what else to tell you.

#include <stdio.h>

        int i;
        for (i = 1; i <= 10000; i*=10) {
                printf("[%8d]\n", i);
        return (0);

$ ./printftest
[       1]
[      10]
[     100]
[    1000]
[   10000]

EDIT: response to clarification of question:

#include <math.h>
int maxval = 1000;
int width = round(1+log(maxval)/log(10));
printf("%*d\n", width, intval);

The width calculation computes log base 10 + 1, which gives the number of digits. The fancy * allows you to use the variable for a value in the format string.

You still have to know the maximum for any given run, but there's no way around that in any language or pencil & paper.

"static const" vs "#define" vs "enum"

We looked at the produced assembler code on the MBF16X... Both variants result in the same code for arithmetic operations (ADD Immediate, for example).

So const int is preferred for the type check while #define is old style. Maybe it is compiler-specific. So check your produced assembler code.

Twitter Bootstrap - full width navbar

Put your <nav>element out from the <div class='container-fluid'>. Ex :-

 ......nav content goes here_x000D_
<div class="container-fluid">_x000D_
   ........ other content goes here_x000D_

How to get column values in one comma separated value

SELECT name, GROUP_CONCAT( section ) 
FROM  `tmp` 

Weird PHP error: 'Can't use function return value in write context'

This error is quite right and highlights a contextual syntax issue. Can be reproduced by performing any kind "non-assignable" syntax. For instance:

function Syntax($hello) { .... then attempt to call the function as though a property and assign a value.... $this->Syntax('Hello') = 'World';

The above error will be thrown because syntactially the statement is wrong. The right assignment of 'World' cannot be written in the context you have used (i.e. syntactically incorrect for this context). 'Cannot use function return value' or it could read 'Cannot assign the right-hand value to the function because its read-only'

The specific error in the OPs code is as highlighted, using brackets instead of square brackets.

Exclude property from type


single property

type T1 = Omit<XYZ, "z"> // { x: number; y: number; }

multiple properties

type T2 = Omit<XYZ, "y" | "z"> // { x: number; } 

properties conditionally

e.g. all string types:
type Keys_StringExcluded<T> = 
  { [K in keyof T]: T[K] extends string ? never : K }[keyof T]

type XYZ = { x: number; y: string; z: number; }
type T3a = Pick<XYZ, Keys_StringExcluded<XYZ>> // { x: number; z: number; }
Shorter version with TS 4.1 key remapping / as clause in mapped types (PR):
type T3b = { [K in keyof XYZ as XYZ[K] extends string ? never : K]: XYZ[K] } 
// { x: number; z: number; }

properties by string pattern

e.g. exclude getters (props with 'get' string prefixes)
type OmitGet<T> = {[K in keyof T as K extends `get${infer _}` ? never : K]: T[K]}

type XYZ2 = { getA: number; b: string; getC: boolean; }
type T4 = OmitGet<XYZ2> //  { b: string; }

Note: Above template literal types are supported with TS 4.1.
Note 2: You can also write get${string} instead of get${infer _} here.

Pick, Omit and other utility types

How to Pick and rename certain keys using Typescript? (rename instead of exclude)


pandas get rows which are NOT in other dataframe

As already hinted at, isin requires columns and indices to be the same for a match. If match should only be on row contents, one way to get the mask for filtering the rows present is to convert the rows to a (Multi)Index:

In [77]: df1 = pandas.DataFrame(data = {'col1' : [1, 2, 3, 4, 5, 3], 'col2' : [10, 11, 12, 13, 14, 10]})
In [78]: df2 = pandas.DataFrame(data = {'col1' : [1, 3, 4], 'col2' : [10, 12, 13]})
In [79]: df1.loc[~df1.set_index(list(df1.columns)).index.isin(df2.set_index(list(df2.columns)).index)]
   col1  col2
1     2    11
4     5    14
5     3    10

If index should be taken into account, set_index has keyword argument append to append columns to existing index. If columns do not line up, list(df.columns) can be replaced with column specifications to align the data.

pandas.MultiIndex.from_tuples(df<N>.to_records(index = False).tolist())

could alternatively be used to create the indices, though I doubt this is more efficient.

Is it ok to run docker from inside docker?

Running Docker inside Docker (a.k.a. dind), while possible, should be avoided, if at all possible. (Source provided below.) Instead, you want to set up a way for your main container to produce and communicate with sibling containers.

Jérôme Petazzoni — the author of the feature that made it possible for Docker to run inside a Docker container — actually wrote a blog post saying not to do it. The use case he describes matches the OP's exact use case of a CI Docker container that needs to run jobs inside other Docker containers.

Petazzoni lists two reasons why dind is troublesome:

  1. It does not cooperate well with Linux Security Modules (LSM).
  2. It creates a mismatch in file systems that creates problems for the containers created inside parent containers.

From that blog post, he describes the following alternative,

[The] simplest way is to just expose the Docker socket to your CI container, by bind-mounting it with the -v flag.

Simply put, when you start your CI container (Jenkins or other), instead of hacking something together with Docker-in-Docker, start it with:

docker run -v /var/run/docker.sock:/var/run/docker.sock ...

Now this container will have access to the Docker socket, and will therefore be able to start containers. Except that instead of starting "child" containers, it will start "sibling" containers.

Best practices to test protected methods with PHPUnit

You can indeed use __call() in a generic fashion to access protected methods. To be able to test this class

class Example {
    protected function getMessage() {
        return 'hello';

you create a subclass in ExampleTest.php:

class ExampleExposed extends Example {
    public function __call($method, array $args = array()) {
        if (!method_exists($this, $method))
            throw new BadMethodCallException("method '$method' does not exist");
        return call_user_func_array(array($this, $method), $args);

Note that the __call() method does not reference the class in any way so you can copy the above for each class with protected methods you want to test and just change the class declaration. You may be able to place this function in a common base class, but I haven't tried it.

Now the test case itself only differs in where you construct the object to be tested, swapping in ExampleExposed for Example.

class ExampleTest extends PHPUnit_Framework_TestCase {
    function testGetMessage() {
        $fixture = new ExampleExposed();
        self::assertEquals('hello', $fixture->getMessage());

I believe PHP 5.3 allows you to use reflection to change the accessibility of methods directly, but I assume you'd have to do so for each method individually.

Efficiently checking if arbitrary object is NaN in Python / numpy / pandas?

I found this brilliant solution here, it uses the simple logic NAN!=NAN.

Using above example you can simply do the following. This should work on different type of objects as it simply utilize the fact that NAN is not equal to NAN.

 import numpy as np
 s = pd.Series(['apple', np.nan, 'banana'])
 s.apply(lambda x: x!=x)
 0    False
 1     True
 2    False
 dtype: bool

PDO support for multiple queries (PDO_MYSQL, PDO_MYSQLND)

As I know, PDO_MYSQLND replaced PDO_MYSQL in PHP 5.3. Confusing part is that name is still PDO_MYSQL. So now ND is default driver for MySQL+PDO.

Overall, to execute multiple queries at once you need:

  • PHP 5.3+
  • mysqlnd
  • Emulated prepared statements. Make sure PDO::ATTR_EMULATE_PREPARES is set to 1 (default). Alternatively you can avoid using prepared statements and use $pdo->exec directly.

Using exec

$db = new PDO("mysql:host=localhost;dbname=test", 'root', '');

// works regardless of statements emulation
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, 0);

$sql = "
INSERT INTO car(name, type) VALUES ('car1', 'coupe'); 
INSERT INTO car(name, type) VALUES ('car2', 'coupe');


Using statements

$db = new PDO("mysql:host=localhost;dbname=test", 'root', '');

// works not with the following set to 0. You can comment this line as 1 is default
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, 1);

$sql = "
INSERT INTO car(name, type) VALUES ('car1', 'coupe'); 
INSERT INTO car(name, type) VALUES ('car2', 'coupe');

$stmt = $db->prepare($sql);

A note:

When using emulated prepared statements, make sure you have set proper encoding (that reflects actual data encoding) in DSN (available since 5.3.6). Otherwise there can be a slight possibility for SQL injection if some odd encoding is used.

What does 'killed' mean when a processing of a huge CSV with Python, which suddenly stops?

I just had the same happen on me when I tried to run a python script from a shared folder in VirtualBox within the new Ubuntu 20.04 LTS. Python bailed with Killed while loading my own personal library. When I moved the folder to a local directory, the issue went away. It appears that the Killed stop happened during the initial imports of my library as I got messages of missing libraries once I moved the folder over.

The issue went away after I restarted my computer.

Therefore, people may want to try moving the program to a local directory if its over a share of some kind or it could be a transient problem that just requires a reboot of the OS.

IndentationError: unindent does not match any outer indentation level

This is because there is a mix-up of both tabs and spaces. You can either remove all the spaces and replace them with tabs.

Or, Try writing this:

#!/usr/bin/python -tt

at the beginning of the code. This line resolves any differences between tabs and spaces.

Bash script and /bin/bash^M: bad interpreter: No such file or directory

This is caused by editing file in windows and importing and executing in unix.

dos2unix -k -o filename should do the trick.

How to convert WebResponse.GetResponseStream return into a string?

You can create a StreamReader around the stream, then call StreamReader.ReadToEnd().

StreamReader responseReader = new StreamReader(request.GetResponse().GetResponseStream());
var responseData = responseReader.ReadToEnd();

CSS3 transform not working

Since nobody referenced relevant documentation:

CSS Transforms Module Level 1 - Terminology - Transformable Element

A transformable element is an element in one of these categories:

  • an element whose layout is governed by the CSS box model which is either a block-level or atomic inline-level element, or whose display property computes to table-row, table-row-group, table-header-group, table-footer-group, table-cell, or table-caption
  • an element in the SVG namespace and not governed by the CSS box model which has the attributes transform, ‘patternTransform‘ or gradientTransform.

In your case, the <a> elements are inline by default.

Changing the display property's value to inline-block renders the elements as atomic inline-level elements, and therefore the elements become "transformable" by definition.

li a {
   display: inline-block;
   -webkit-transform: rotate(10deg);
   -moz-transform: rotate(10deg);
   -o-transform: rotate(10deg); 
   transform: rotate(10deg);

As mentioned above, this only seems to applicable in -webkit based browsers since it appears to work in IE/FF regardless.

Get enum values as List of String in Java 8

You could also do something as follow

public enum DAY {MON, TUES, WED, THU, FRI, SAT, SUN};
EnumSet.allOf(DAY.class).stream().map(e ->



The main reason why I stumbled across this question is that I wanted to write a generic validator that validates whether a given string enum name is valid for a given enum type (Sharing in case anyone finds useful).

For the validation, I had to use Apache's EnumUtils library since the type of enum is not known at compile time.

@SuppressWarnings({ "unchecked", "rawtypes" })
public static void isValidEnumsValid(Class clazz, Set<String> enumNames) {
    Set<String> notAllowedNames =
            .filter(enumName -> !EnumUtils.isValidEnum(clazz, enumName))

    if (notAllowedNames.size() > 0) {
        String validEnumNames = (String) EnumUtils.getEnumMap(clazz).keySet().stream()
            .collect(Collectors.joining(", "));

        throw new IllegalArgumentException("The requested values '" +
                .collect(Collectors.joining(",")) + "' are not valid. Please select one more (case-sensitive) "
                + "of the following : " + validEnumNames);

I was too lazy to write an enum annotation validator as shown in here

Remove specific characters from a string in Javascript

if it is not the first two chars and you wanna remove F0 from the whole string then you gotta use this regex

   let string = 'F0123F0456F0';_x000D_
   let result = string.replace(/F0/ig, '');_x000D_

What is the regular expression to allow uppercase/lowercase (alphabetical characters), periods, spaces and dashes only?

The regex you're looking for is ^[A-Za-z.\s_-]+$

  • ^ asserts that the regular expression must match at the beginning of the subject
  • [] is a character class - any character that matches inside this expression is allowed
  • A-Z allows a range of uppercase characters
  • a-z allows a range of lowercase characters
  • . matches a period rather than a range of characters
  • \s matches whitespace (spaces and tabs)
  • _ matches an underscore
  • - matches a dash (hyphen); we have it as the last character in the character class so it doesn't get interpreted as being part of a character range. We could also escape it (\-) instead and put it anywhere in the character class, but that's less clear
  • + asserts that the preceding expression (in our case, the character class) must match one or more times
  • $ Finally, this asserts that we're now at the end of the subject

When you're testing regular expressions, you'll likely find a tool like regexpal helpful. This allows you to see your regular expression match (or fail to match) your sample data in real time as you write it.

How do you configure HttpOnly cookies in tomcat / java webapps?

also it should be noted that turning on HttpOnly will break applets that require stateful access back to the jvm.

the Applet http requests will not use the jsessionid cookie and may get assigned to a different tomcat.

What is the difference between single and double quotes in SQL?

In ANSI SQL, double quotes quote object names (e.g. tables) which allows them to contain characters not otherwise permitted, or be the same as reserved words (Avoid this, really).

Single quotes are for strings.

However, MySQL is oblivious to the standard (unless its SQL_MODE is changed) and allows them to be used interchangably for strings.

Moreover, Sybase and Microsoft also use square brackets for identifier quoting.

So it's a bit vendor specific.

Other databases such as Postgres and IBM actually adhere to the ansi standard :)

How to convert .pem into .key?

If you're looking for a file to use in httpd-ssl.conf as a value for SSLCertificateKeyFile, a PEM file should work just fine.

See this SO question/answer for more details on the SSL options in that file.

Why is SSLCertificateKeyFile needed for Apache?

"%%" and "%/%" for the remainder and the quotient

In R, you can assign your own operators using %[characters]%. A trivial example:

'%p%' <- function(x, y){x^2 + y}

2 %p% 3 # result: 7

While I agree with BlueTrin that %% is pretty standard, I have a suspicion %/% may have something to do with the sort of operator definitions I showed above - perhaps it was easier to implement, and makes sense: %/% means do a special sort of division (integer division)

Fixing npm path in Windows 8 and 10

If you can't work with npm packages, you propably has bad config with npm install packages, you try this:

Run the following command in your terminal to revert back to the default registry

npm config set registry

How can I exclude $(this) from a jQuery selector?

You should use the "siblings()" method, and prevent from running the ".content a" selector over and over again just for applying that effect:


<div class="content">
    <a href="#">A</a>
<div class="content">
    <a href="#">B</a>
<div class="content">
    <a href="#">C</a>


.content {
.content.other {


$(".content a").click(function() {
  var current = $(this).parent();

See here:

Batch file to run a command in cmd within a directory

CMD.EXE will not execute internal commands contained inside the string. Only actual files can be launched with that string.

You will need to actually call a batch file to do what you want.


start cmd.exe /k bat2.bat


cd C:\activiti-5.9\setup
ant demo.start

You may want to create a folder called BAT, and add it's location to your path. So if you create C:\BAT, add C:\BAT\; to the path. The path is located at:

    click -> Start -> right-click Computer -> Properties ->
    click -> Avanced System Settings -> Environment Variables
   select -> Path (From either list. User Variables are specific to 
                   your profile, System Variables are, duh, system-wide.)
    Click -> Edit
Press the -> the [END] or [HOME] key.
     Type -> C:\BAT\;
    Click -> OK -> OK

Now place all your batch files in C:\BAT and they will be found, regardless of the current directory.

Can you find all classes in a package using reflection?

You should probably take a look at the open source Reflections library. With it you can easily achieve what you want.

First, setup the reflections index (it's a bit messy since searching for all classes is disabled by default):

List<ClassLoader> classLoadersList = new LinkedList<ClassLoader>();

Reflections reflections = new Reflections(new ConfigurationBuilder()
    .setScanners(new SubTypesScanner(false /* don't exclude Object.class */), new ResourcesScanner())
    .setUrls(ClasspathHelper.forClassLoader(classLoadersList.toArray(new ClassLoader[0])))
    .filterInputsBy(new FilterBuilder().include(FilterBuilder.prefix("org.your.package"))));

Then you can query for all objects in a given package:

Set<Class<?>> classes = reflections.getSubTypesOf(Object.class);

Running unittest with typical test directory structure

What's the usual way of actually running the tests

I use Python 3.6.2

cd new_project

pytest test/

To install pytest: sudo pip install pytest

I didn't set any path variable and my imports are not failing with the same "test" project structure.

I commented out this stuff: if __name__ == '__main__' like this:

import antigravity

class TestAntigravity(unittest.TestCase):

    def test_something(self):

        # ... test stuff here

# if __name__ == '__main__':
#     if __package__ is None:
#         import something
#         sys.path.append(path.dirname(path.dirname(path.abspath(__file__))))
#         from .. import antigravity
#     else:
#         from .. import antigravity
#     unittest.main()

How can I reduce the waiting (ttfb) time

I would suggest you read this article and focus more on how to optimize the overall response to the user request (either a page, a search result etc.)

A good argument for this is the example they give about using gzip to compress the page. Even though ttfb is faster when you do not compress, the overall experience of the user is worst because it takes longer to download content that is not zipped.

Printing everything except the first field with awk

Maybe the most concise way:

$ awk '{$(NF+1)=$1;$1=""}sub(FS,"")' infile
United Arab Emirates AE
Antigua & Barbuda AG
Netherlands Antilles AN
American Samoa AS
Bosnia and Herzegovina BA
Burkina Faso BF
Brunei Darussalam BN


$(NF+1)=$1: Generator of a "new" last field.

$1="": Set the original first field to null

sub(FS,""): After the first two actions {$(NF+1)=$1;$1=""} get rid of the first field separator by using sub. The final print is implicit.

Trouble Connecting to sql server Login failed. "The login is from an untrusted domain and cannot be used with Windows authentication"

Joining a WORKGROUP then rejoining the domain fixed this issue for me.

I got this error while using Virtual Box VM's. The issue started to happen when I moved the VM files to a new drive location or computer.

Hope this helps the VM folks.

How do I save and restore multiple variables in python?

There is a built-in library called pickle. Using pickle you can dump objects to a file and load them later.

import pickle

f = open('store.pckl', 'wb')
pickle.dump(obj, f)

f = open('store.pckl', 'rb')
obj = pickle.load(f)

Best way to define private methods for a class in Objective-C

One more thing that I haven't seen mentioned here - Xcode supports .h files with "_private" in the name. Let's say you have a class MyClass - you have MyClass.m and MyClass.h and now you can also have MyClass_private.h. Xcode will recognize this and include it in the list of "Counterparts" in the Assistant Editor.

#import "MyClass.h"
#import "MyClass_private.h"

How can I get around MySQL Errcode 13 with SELECT INTO OUTFILE?

Does Ubuntu use SELinux? Check to see if it's enabled and enforcing. /var/log/audit/audit.log may be helpul (if that's where Ubuntu sticks it -- that's the RHEL/Fedora location).

Undefined Symbols for architecture x86_64: Compiling problems

There's no mystery here, the linker is telling you that you haven't defined the missing symbols, and you haven't.

Similarity::Similarity() or Similarity::~Similarity() are just missing and you have defined the others incorrectly,

void Similarity::readData(Scanner& inStream){


void readData(Scanner& inStream){

etc. etc.

The second one is a function called readData, only the first is the readData method of the Similarity class.

To be clear about this, in Similarity.h

void readData(Scanner& inStream);

but in Similarity.cpp

void Similarity::readData(Scanner& inStream){

How to include static library in makefile


LDFLAGS= -L<Directory where the library resides> -l<library name>

Like :

LDFLAGS = -L. -lmine

for ensuring static compilation you can also add

LDFLAGS = -static

Or you can just get rid of the whole library searching, and link with with it directly.

say you have main.c fun.c

and a static library libmine.a

then you can just do in your final link line of the Makefile

$(CC) $(CFLAGS) main.o fun.o libmine.a

Java Long primitive type maximum limit

Exceding the maximum value of a long doesnt throw an exception, instead it cicles back. If you do this:

Long.MAX_VALUE + 1

you will notice that the result is the equivalent to Long.MIN_VALUE.

From here: java number exceeds long.max_value - how to detect?

Bash tool to get nth line from a file

The fastest solution for big files is always tail|head, provided that the two distances:

  • from the start of the file to the starting line. Lets call it S
  • the distance from the last line to the end of the file. Be it E

are known. Then, we could use this:

mycount="$E"; (( E > S )) && mycount="+$S"
howmany="$(( endline - startline + 1 ))"
tail -n "$mycount"| head -n "$howmany"

howmany is just the count of lines required.

Some more detail in

MongoDb query condition on comparing 2 fields

You can use a $where. Just be aware it will be fairly slow (has to execute Javascript code on every record) so combine with indexed queries if you can.

db.T.find( { $where: function() { return this.Grade1 > this.Grade2 } } );

or more compact:

db.T.find( { $where : "this.Grade1 > this.Grade2" } );

UPD for mongodb v.3.6+

you can use $expr as described in recent answer

fast way to copy formatting in excel

You could have simply used Range("x1").value(11) something like below:

Sheets("Output").Range("$A$1:$A$500").value(11) =  Sheets(sheet_).Range("$A$1:$A$500").value(11)

range has default property "Value" plus value can have 3 optional orguments 10,11,12. 11 is what you need to tansfer both value and formats. It doesn't use clipboard so it is faster.- Durgesh

How to find the parent element using javascript

Using plain javascript:


In jQuery:

element.parent() :connection timed out: connect?

The error message says it all: your connection timed out. This means your request did not get a response within some (default) timeframe. The reasons that no response was received is likely to be one of:

  • a) The IP/domain or port is incorrect
  • b) The IP/domain or port (i.e service) is down
  • c) The IP/domain is taking longer than your default timeout to respond
  • d) You have a firewall that is blocking requests or responses on whatever port you are using
  • e) You have a firewall that is blocking requests to that particular host
  • f) Your internet access is down

Note that firewalls and port or IP blocking may be in place by your ISP

ERROR 1044 (42000): Access denied for 'root' With All Privileges

First, Identify the user you are logged in as:

 select user();
 select current_user();

The result for the first command is what you attempted to login as, the second is what you actually connected as. Confirm that you are logged in as root@localhost in mysql.

Grant_priv to root@localhost. Here is how you can check.

mysql> SELECT host,user,password,Grant_priv,Super_priv FROM mysql.user;
| host      | user             | password                                  | Grant_priv | Super_priv |
| localhost | root             | ***************************************** | N          | Y          |
| localhost | debian-sys-maint | ***************************************** | Y          | Y          |
| localhost | staging          | ***************************************** | N          | N          |

You can see that the Grant_priv is set to N for root@localhost. This needs to be Y. Below is how to fixed this:

UPDATE mysql.user SET Grant_priv='Y', Super_priv='Y' WHERE User='root';
GRANT ALL ON *.* TO 'root'@'localhost';

I logged back in, it was fine.

How to add external fonts to android application

You can use the custom TextView for whole app with custom font here is an example for that

public class MyTextView extends TextView {

   Typeface normalTypeface = Typeface.createFromAsset(getContext().getAssets(), Constants.FONT_REGULAR);
   Typeface boldTypeface = Typeface.createFromAsset(getContext().getAssets(),  Constants.FONT_BOLD);

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

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

   public MyTextView(Context context) {

   public void setTypeface(Typeface tf, int style) {
       if (style == Typeface.BOLD) {
           super.setTypeface(boldTypeface/*, -1*/);
       } else {
           super.setTypeface(normalTypeface/*, -1*/);

Writing Unicode text to a text file?

Preface: will your viewer work?

Make sure your viewer/editor/terminal (however you are interacting with your utf-8 encoded file) can read the file. This is frequently an issue on Windows, for example, Notepad.

Writing Unicode text to a text file?

In Python 2, use open from the io module (this is the same as the builtin open in Python 3):

import io

Best practice, in general, use UTF-8 for writing to files (we don't even have to worry about byte-order with utf-8).

encoding = 'utf-8'

utf-8 is the most modern and universally usable encoding - it works in all web browsers, most text-editors (see your settings if you have issues) and most terminals/shells.

On Windows, you might try utf-16le if you're limited to viewing output in Notepad (or another limited viewer).

encoding = 'utf-16le' # sorry, Windows users... :(

And just open it with the context manager and write your unicode characters out:

with, 'w', encoding=encoding) as f:

Example using many Unicode characters

Here's an example that attempts to map every possible character up to three bits wide (4 is the max, but that would be going a bit far) from the digital representation (in integers) to an encoded printable output, along with its name, if possible (put this into a file called

from __future__ import print_function
import io
from unicodedata import name, category
from curses.ascii import controlnames
from collections import Counter

try: # use these if Python 2
    unicode_chr, range = unichr, xrange
except NameError: # Python 3
    unicode_chr = chr

exclude_categories = set(('Co', 'Cn'))
counts = Counter()
control_names = dict(enumerate(controlnames))
with'unidata', 'w', encoding='utf-8') as f:
    for x in range((2**8)**3): 
            char = unicode_chr(x)
        except ValueError:
            continue # can't map to unicode, try next x
        cat = category(char)
        if cat in exclude_categories:
            continue # get rid of noise & greatly shorten result file
            uname = name(char)
        except ValueError: # probably control character, don't use actual
            uname = control_names.get(x, '')
            f.write(u'{0:>6x} {1}    {2}\n'.format(x, cat, uname))
            f.write(u'{0:>6x} {1}  {2}  {3}\n'.format(x, cat, char, uname))
# may as well describe the types we logged.
for cat, count in counts.items():
    print('{0} chars of category, {1}'.format(count, cat))

This should run in the order of about a minute, and you can view the data file, and if your file viewer can display unicode, you'll see it. Information about the categories can be found here. Based on the counts, we can probably improve our results by excluding the Cn and Co categories, which have no symbols associated with them.

$ python

It will display the hexadecimal mapping, category, symbol (unless can't get the name, so probably a control character), and the name of the symbol. e.g.

I recommend less on Unix or Cygwin (don't print/cat the entire file to your output):

$ less unidata

e.g. will display similar to the following lines which I sampled from it using Python 2 (unicode 5.2):

     0 Cc NUL
    20 Zs     SPACE
    b6 So  ¶  PILCROW SIGN
   e59 Nd  ?  THAI DIGIT NINE
  2887 So  ?  BRAILLE PATTERN DOTS-1238

My Python 3.5 from Anaconda has unicode 8.0, I would presume most 3's would.

Common MySQL fields and their appropriate data types

In my experience, first name/last name fields should be at least 48 characters -- there are names from some countries such as Malaysia or India that are very long in their full form.

Phone numbers and postcodes you should always treat as text, not numbers. The normal reason given is that there are postcodes that begin with 0, and in some countries, phone numbers can also begin with 0. But the real reason is that they aren't numbers -- they're identifiers that happen to be made up of numerical digits (and that's ignoring countries like Canada that have letters in their postcodes). So store them in a text field.

In MySQL you can use VARCHAR fields for this type of information. Whilst it sounds lazy, it means you don't have to be too concerned about the right minimum size.

How to define Singleton in TypeScript

You can use class expressions for this (as of 1.6 I believe).

var x = new (class {
    /* ... lots of singleton logic ... */
    public someMethod() { ... }

or with the name if your class needs to access its type internally

var x = new (class Singleton {
    /* ... lots of singleton logic ... */
    public someMethod(): Singleton { ... }

Another option is to use a local class inside of your singleton using some static members

class Singleton {

    private static _instance;
    public static get instance() {

        class InternalSingleton {
            someMethod() { }

            //more singleton logic

        if(!Singleton._instance) {
            Singleton._instance = new InternalSingleton();

        return <InternalSingleton>Singleton._instance;

var x = Singleton.instance;

PHP Function Comments

You can get the comments of a particular method by using the ReflectionMethod class and calling ->getDocComment().

Creating/writing into a new file in Qt

Are you sure you're in the right directory?
Opening a file without a full path will open it in the current working directory. In most cases this is not what you want. Try changing the first line to

QString filename="c:\\Data.txt" or
QString filename="c:/Data.txt"

and see if the file is created in c:\

How to best display in Terminal a MySQL SELECT returning too many fields?

Using mysql's ego command

From mysql's help command:

ego          (\G) Send command to mysql server, display result vertically.

So by appending a \G to your select, you can get a very clean vertical output:

mysql> SELECT * FROM sometable \G

Using a pager

You can tell MySQL to use the less pager with its -S option that chops wide lines and gives you an output that you can scroll with the arrow keys:

mysql> pager less -S

Thus, next time you run a command with a wide output, MySQL will let you browse the output with the less pager:

mysql> SELECT * FROM sometable;

If you're done with the pager and want to go back to the regular output on stdout, use this:

mysql> nopager

How to generate a GUID in Oracle?

Example found on:

SELECT REGEXP_REPLACE(SYS_GUID(), '(.{8})(.{4})(.{4})(.{4})(.{12})', '\1-\2-\3-\4-\5') MSSQL_GUID  FROM DUAL 



Excel Formula to SUMIF date falls in particular month

=SUMPRODUCT( (MONTH($A$2:$A$6)=1) * ($B$2:$B$6) )


  • (MONTH($A$2:$A$6)=1) creates an array of 1 and 0, it's 1 when the month is january, thus in your example the returned array would be [1, 1, 1, 0, 0]

  • SUMPRODUCT first multiplies each value of the array created in the above step with values of the array ($B$2:$B$6), then it sums them. Hence in your example it does this: (1 * 430) + (1 * 96) + (1 * 440) + (0 * 72.10) + (0 * 72.30)

This works also in OpenOffice and Google Spreadsheets

angular ng-repeat in reverse

The orderBy filter performs a stable sorting as of Angular 1.4.5. (See the GitHub pull request

So it is sufficient to use a constant predicate and reverse set to true:

<div ng-repeat="friend in friends | orderBy:0:true">{{}}</div>

Method List in Visual Studio Code

Take a look at Show Functions plugin. It can list functions, symbols, bookmarks by configurable regular expressions. Regular expressions are a real saver, expecially when you're not using a mainstream language and when CodeOutline doesn't do the job. It's ugly to see a split window with these functions (CodeOutline seems to be better integrated) but at least there's something to use

Clear form fields with jQuery

If you want to empty all input boxes irrespective of its type then it's a minute step by


How to check if variable is array?... or something array-like

If you are using foreach inside a function and you are expecting an array or a Traversable object you can type hint that function with:

function myFunction(array $a)
function myFunction(Traversable)

If you are not using foreach inside a function or you are expecting both you can simply use this construct to check if you can iterate over the variable:

if (is_array($a) or ($a instanceof Traversable))

EditText request focus

youredittext.requestFocus() call it from activity


and use the above code there

Android WebView not loading URL

Did you added the internet permission in your manifest file ? if not add the following line.

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

hope this will help you.


Use the below lines.

    public class WebViewDemo extends Activity {

        private WebView webView;

        Activity activity ;
        private ProgressDialog progDailog; 

        public void onCreate(Bundle savedInstanceState) {

            activity = this;

            progDailog =, "Loading","Please wait...", true);

           webView = (WebView) findViewById(;

            webView.setWebViewClient(new WebViewClient(){

                public boolean shouldOverrideUrlLoading(WebView view, String url) {

                    return true;                
                public void onPageFinished(WebView view, final String url) {



How to get a list of column names

If you are using the command line shell to SQLite then .headers on before you perform your query. You only need to do this once in a given session.

CSS opacity only to background color, not the text on it?

I had the same problem. I want a 100% transparent background color. Just use this code; it's worked great for me:

rgba(54, 25, 25, .00004);

You can see examples on the left side on this web page (the contact form area).

When is it appropriate to use C# partial classes?

It is true that Partial Class is used in auto code generation, one use can be maintaining a large class file which might have thousand lines of code. You never know your class might end up with 10 thousand lines and you don't want to create a new class with different name.

public partial class Product
    // 50 business logic embedded in methods and properties..

public partial class Product
    // another 50 business logic embedded in methods and properties..
//finally compile with product.class file.

Another possible use could be that more than one developer can work on the same class as they are stored at different places. People might laugh but you never know it can be handful sometimes.


public partial class Product
    //you are writing the business logic for fast moving product


public partial class Product
    // Another developer writing some business logic...

Hope it makes sense!

Creating PHP class instance with a string

You can simply use the following syntax to create a new class (this is handy if you're creating a factory):

$className = $whatever;
$object = new $className;

As an (exceptionally crude) example factory method:

public function &factory($className) {

    require_once($className . '.php');
    if(class_exists($className)) return new $className;

    die('Cannot create new "' . $className . '" class - includes not found or class unavailable.');

XMLHttpRequest cannot load an URL with jQuery

You can't do a XMLHttpRequest crossdomain, the only "option" would be a technique called JSONP, which comes down to this:

To start request: Add a new <script> tag with the remote url, and then make sure that remote url returns a valid javascript file that calls your callback function. Some services support this (and let you name your callback in a GET parameters).

The other easy way out, would be to create a "proxy" on your local server, which gets the remote request and then just "forwards" it back to your javascript.


I see jQuery has built-in support for JSONP, by checking if the URL contains "callback=?" (where jQuery will replace ? with the actual callback method). But you'd still need to process that on the remote server to generate a valid response.

How to see if an object is an array without using reflection?

Simply obj instanceof Object[] (tested on JShell).

When to use RabbitMQ over Kafka?

Use RabbitMQ when:

  • You don’t have to handle with Bigdata and you prefer a convenient in-built UI for monitoring
  • No need of automatically replicable queues
  • No multi subscribers for the messages- Since unlike Kafka which is a log, RabbitMQ is a queue and messages are removed once consumed and acknowledgment arrived
  • If you have the requirements to use Wildcards and regex for messages
  • If defining message priority is important

In Short: RabbitMQ is good for simple use cases, with low traffic of data, with the benefit of priority queue and flexible routing options. For massive data and high throughput use Kafka.

How to resolve this JNI error when trying to run LWJGL "Hello World"?

A CLASSPATH entry is either a directory at the head of a package hierarchy of .class files, or a .jar file. If you're expecting ./lib to include all the .jar files in that directory, it won't. You have to name them explicitly.

How to modify a text file?

Rewriting a file in place is often done by saving the old copy with a modified name. Unix folks add a ~ to mark the old one. Windows folks do all kinds of things -- add .bak or .old -- or rename the file entirely or put the ~ on the front of the name.

import shutil
shutil.move( afile, afile+"~" )

destination= open( aFile, "w" )
source= open( aFile+"~", "r" )
for line in source:
    destination.write( line )
    if <some condition>:
        destination.write( >some additional line> + "\n" )

Instead of shutil, you can use the following.

import os
os.rename( aFile, aFile+"~" )

How do I get which JRadioButton is selected from a ButtonGroup

You could use getSelectedObjects() of ItemSelectable (superinterface of ButtonModel) which returns the list of selected items. In case of a radio button group it can only be one or none at all.

#1071 - Specified key was too long; max key length is 767 bytes

I fixed this issue with :


replaced with


all the unique or primary varchar keys which have more than 200 replace them with 191 or set them as text.

How to resolve TypeError: can only concatenate str (not "int") to str

Python working a bit differently to JavaScript for example, the value you are concatenating needs to be same type, both int or str...

So for example the code below throw an error:

print( "Alireza" + 1980)

like this:

Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    print( "Alireza" + 1980)
TypeError: can only concatenate str (not "int") to str

To solve the issue, just add str to your number or value like:

print( "Alireza" + str(1980))

And the result as:


Find a value in DataTable

this question asked in 2009 but i want to share my codes:

    Public Function RowSearch(ByVal dttable As DataTable, ByVal searchcolumns As String()) As DataTable

    Dim x As Integer
    Dim y As Integer

    Dim bln As Boolean

    Dim dttable2 As New DataTable
    For x = 0 To dttable.Columns.Count - 1

    For x = 0 To dttable.Rows.Count - 1
        For y = 0 To searchcolumns.Length - 1
            If String.IsNullOrEmpty(searchcolumns(y)) = False Then
                If searchcolumns(y) = CStr(dttable.Rows(x)(y + 1) & "") & "" Then
                    bln = True
                    bln = False
                    Exit For
                End If
            End If
        If bln = True Then
        End If

    Return dttable2

End Function

PHP output showing little black diamonds with a question mark

If you see that character (? U+FFFD "REPLACEMENT CHARACTER") it usually means that the text itself is encoded in some form of single byte encoding but interpreted in one of the unicode encodings (UTF8 or UTF16).

If it were the other way around it would (usually) look something like this: ä.

Probably the original encoding is ISO-8859-1, also known as Latin-1. You can check this without having to change your script: Browsers give you the option to re-interpret a page in a different encoding -- in Firefox use "View" -> "Character Encoding".

To make the browser use the correct encoding, add an HTTP header like this:

header("Content-Type: text/html; charset=ISO-8859-1");

or put the encoding in a meta tag:

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

Alternatively you could try to read from the database in another encoding (UTF-8, preferably) or convert the text with iconv().

How do I redirect output to a variable in shell?

I got error sometimes when using $(`code`) constructor.

Finally i got some approach to that here:

Basically, using Tee to read again the ouput and putting it into a variable. Theres how you see the normal output then read it from the ouput.

is not? I guess your current task genhash will output just that, a single string hash so might work for you.

Im so neewbie and still looking for full output & save into 1 command. Regards.

What is the correct way to declare a boolean variable in Java?

First of all, you should use none of them. You are using wrapper type, which should rarely be used in case you have a primitive type. So, you should use boolean rather.

Further, we initialize the boolean variable to false to hold an initial default value which is false. In case you have declared it as instance variable, it will automatically be initialized to false.

But, its completely upto you, whether you assign a default value or not. I rather prefer to initialize them at the time of declaration.

But if you are immediately assigning to your variable, then you can directly assign a value to it, without having to define a default value.

So, in your case I would use it like this: -

boolean isMatch = email1.equals (email2);

How to normalize a histogram in MATLAB?

Since 2014b, Matlab has these normalization routines embedded natively in the histogram function (see the help file for the 6 routines this function offers). Here is an example using the PDF normalization (the sum of all the bins is 1).

data = 2*randn(5000,1) + 5;             % generate normal random (m=5, std=2)
h = histogram(data,'Normalization','pdf')   % PDF normalization

The corresponding PDF is

Nbins = h.NumBins;
edges = h.BinEdges; 
x = zeros(1,Nbins);
for counter=1:Nbins
    midPointShift = abs(edges(counter)-edges(counter+1))/2;
    x(counter) = edges(counter)+midPointShift;

mu = mean(data);
sigma = std(data);

f = exp(-(x-mu).^2./(2*sigma^2))./(sigma*sqrt(2*pi));

The two together gives

hold on;

enter image description here

An improvement that might very well be due to the success of the actual question and accepted answer!

EDIT - The use of hist and histc is not recommended now, and histogram should be used instead. Beware that none of the 6 ways of creating bins with this new function will produce the bins hist and histc produce. There is a Matlab script to update former code to fit the way histogram is called (bin edges instead of bin centers - link). By doing so, one can compare the pdf normalization methods of @abcd (trapz and sum) and Matlab (pdf).

The 3 pdf normalization method give nearly identical results (within the range of eps).


A = randn(10000,1);
centers = -6:0.5:6;
d = diff(centers)/2;
edges = [centers(1)-d(1), centers(1:end-1)+d, centers(end)+d(end)];
edges(2:end) = edges(2:end)+eps(edges(2:end));

title('HIST not normalized');

h = histogram(A,edges);
title('HISTOGRAM not normalized');

[counts, centers] = hist(A,centers); %get the count with hist
title('HIST with PDF normalization');

h = histogram(A,edges,'Normalization','pdf')
title('HISTOGRAM with PDF normalization');

dx = diff(centers(1:2))
normalization_difference_trapz = abs(counts/trapz(centers,counts) - h.Values);
normalization_difference_sum = abs(counts/sum(counts*dx) - h.Values);


enter image description here

The maximum difference between the new PDF normalization and the former one is 5.5511e-17.

Java - Writing strings to a CSV file

Answer for this question is good if you want to overwrite your file everytime you rerun your program, but if you want your records to not be lost at rerunning your program, you may want to try this

public void writeAudit(String actionName) {
    String whereWrite = "./csvFiles/audit.csv";

    try {
        FileWriter fw = new FileWriter(whereWrite, true);
        BufferedWriter bw = new BufferedWriter(fw);
        PrintWriter pw = new PrintWriter(bw);

        Date date = new Date();

        pw.println(actionName + "," + date.toString());

    } catch (FileNotFoundException e) {
    } catch (IOException e) {

The total number of locks exceeds the lock table size

This issue can be resolved by setting the higher values for the MySQL variable innodb_buffer_pool_size. The default value for innodb_buffer_pool_size will be 8,388,608.

To change the settings value for innodb_buffer_pool_size please see the below set.

  1. Locate the file my.cnf from the server. For Linux servers this will be mostly at /etc/my.cnf
  2. Add the line innodb_buffer_pool_size=64MB to this file
  3. Restart the MySQL server

To restart the MySQL server, you can use anyone of the below 2 options:

  1. service mysqld restart
  2. /etc/init.d/mysqld restart

Reference The total number of locks exceeds the lock table size

Solve error javax.mail.AuthenticationFailedException

You should change the port to 587, I tested your code and it's working fine

If error still happens, please change session variable to code below:

Session session = Session.getInstance(props, new javax.mail.Authenticator() {
    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication(userName, password);

How to select all textareas and textboxes using jQuery?

$("**:**input[type=text], :input[type='textarea']").css({width: '90%'});

Passing an Object from an Activity to a Fragment

Passing arguments by bundle is restricted to some data types. But you can transfer any data to your fragment this way:

In your fragment create a public method like this

public void passData(Context context, List<LexItem> list, int pos) {
    mContext = context;
    mLexItemList = list;
    mIndex = pos;

and in your activity call passData() with all your needed data types after instantiating the fragment

        WebViewFragment myFragment = new WebViewFragment();
        myFragment.passData(getApplicationContext(), mLexItemList, index);
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.add(, myFragment);

Remark: My fragment extends "", therefore I have to use "getSupportFragmentManager()". Of course, this principle will work also with a fragment class extending "Fragment", but then you have to use "getFragmentManager()".

How to perform a LEFT JOIN in SQL Server between two SELECT statements?

Try this:

SELECT user.userID, edge.TailUser, edge.Weight 
FROM user
LEFT JOIN edge ON edge.HeadUser = User.UserID
WHERE edge.HeadUser=5043


AND edge.HeadUser=5043

instead of WHERE clausule.

Override intranet compatibility mode IE8

It is possible to override the compatibility mode in intranet.

For IIS, just add the below code to the web.config. Worked for me with IE9.

      <clear />
      <add name="X-UA-Compatible" value="IE=edge" />

Equivalent for Apache:

Header set X-UA-Compatible: IE=Edge

And for nginx:

add_header "X-UA-Compatible" "IE=Edge";

And for express.js:

res.set('X-UA-Compatible', 'IE=Edge')

Regex pattern for numeric values


I'd just use "[0-9]+" to represent positive whole numbers.

How to get the size of a range in Excel

The Range object has both width and height properties, which are measured in points.

Django - taking values from POST request

For django forms you can do this;

form = UserLoginForm(data=request.POST) #getting the whole data from the user.
user = #saving the details obtained from the user.
username = user.cleaned_data.get("username") #where "username" in parenthesis is the name of the Charfield (the variale name i.e, username = forms.Charfield(max_length=64))

How to use concerns in Rails 4

This post helped me understand concerns.

# app/models/trader.rb
class Trader
  include Shared::Schedule

# app/models/concerns/shared/schedule.rb
module Shared::Schedule
  extend ActiveSupport::Concern

Error 5 : Access Denied when starting windows service

Right click on the service in service.msc and select property.

You will see a folder path under Path to executable like C:\Users\Me\Desktop\project\Tor\Tor\tor.exe

Navigate to C:\Users\Me\Desktop\project\Tor and right click on Tor.

Select property, security, edit and then add. In the text field enter LOCAL SERVICE, click ok and then check the box FULL CONTROL

Click on add again then enter NETWORK SERVICE, click ok, check the box FULL CONTROL

Then click ok (at the bottom)

How can I create an error 404 in PHP?

Create custom error pages through .htaccess file

1. 404 - page not found

 RewriteEngine On
 ErrorDocument 404 /404.html

2. 500 - Internal Server Error

RewriteEngine On
ErrorDocument 500 /500.html

3. 403 - Forbidden

RewriteEngine On
ErrorDocument 403 /403.html

4. 400 - Bad request

RewriteEngine On
ErrorDocument 400 /400.html

5. 401 - Authorization Required

RewriteEngine On
ErrorDocument 401 /401.html

You can also redirect all error to single page. like

RewriteEngine On
ErrorDocument 404 /404.html
ErrorDocument 500 /404.html
ErrorDocument 403 /404.html
ErrorDocument 400 /404.html
ErrorDocument 401 /401.html

How to find third or n?? maximum salary from salary table?

If you want optimize way means use TOP Keyword, So the nth max and min salaries query as follows but the queries look like a tricky as in reverse order by using aggregate function names:

N maximum salary:

FROM Salary
WHERE EmpSalary IN(SELECT TOP N EmpSalary FROM Salary ORDER BY EmpSalary DESC) 

for Ex: 3 maximum salary:

FROM Salary
WHERE EmpSalary IN(SELECT TOP 3 EmpSalary FROM Salary ORDER BY EmpSalary DESC) 

N minimum salary:

FROM Salary
WHERE EmpSalary IN(SELECT TOP N EmpSalary FROM Salary ORDER BY EmpSalary ASC)

for Ex: 3 minimum salary:

FROM Salary
WHERE EmpSalary IN(SELECT TOP 3 EmpSalary FROM Salary ORDER BY EmpSalary ASC)

Beautiful way to remove GET-variables with PHP?

If the URL that you are trying to remove the query string from is the current URL of the PHP script, you can use one of the previously mentioned methods. If you just have a string variable with a URL in it and you want to strip off everything past the '?' you can do:

$pos = strpos($url, "?");
$url = substr($url, 0, $pos);

How to convert a file to utf-8 in Python?

Thanks for the replies, it works!

And since the source files are in mixed formats, I added a list of source formats to be tried in sequence (sourceFormats), and on UnicodeDecodeError I try the next format:

from __future__ import with_statement

import os
import sys
import codecs
from chardet.universaldetector import UniversalDetector

targetFormat = 'utf-8'
outputDir = 'converted'
detector = UniversalDetector()

def get_encoding_type(current_file):
    for line in file(current_file):
        if detector.done: break
    return detector.result['encoding']

def convertFileBestGuess(filename):
   sourceFormats = ['ascii', 'iso-8859-1']
   for format in sourceFormats:
        with, 'rU', format) as sourceFile:
      except UnicodeDecodeError:

def convertFileWithDetection(fileName):
    print("Converting '" + fileName + "'...")
        with, 'rU', format) as sourceFile:
    except UnicodeDecodeError:

    print("Error: failed to convert '" + fileName + "'.")

def writeConversion(file):
    with + '/' + fileName, 'w', targetFormat) as targetFile:
        for line in file:

# Off topic: get the file list and call convertFile on each file
# ...

(EDIT by Rudro Badhon: this incorporates the original try multiple formats until you don't get an exception as well as an alternate approach that uses chardet.universaldetector)

How To Remove Outline Border From Input Button

Removing nessorry accessible event not a good idea in up to standard web developments. either way if you looking for a solution removing just the outline doesn't solve the problem. you also have to remove the blue color shadow. for specific scenarios use a separate class name to isolate the this special style to your button.

.btn.focus, .btn:focus {
    outline: 0;
    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, .25);

Better do this

.remove-border.focus, .remove-border:focus {
        outline: 0;
        box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, .25);

How can I make XSLT work in chrome?


This site is built with XML/XSLT client-side. It works on IE6-7-8, FF, O, Safari and Chrome. Are you sending HTTP headers correctly? Are you respecting the same-origin policy?

Sublime Text 2 keyboard shortcut to open file in specified browser (e.g. Chrome)

You can install SideBarEnhancements plugin, which among other things will give you ability to open file in browser just by clicking F12.

To open exactly in Chrome, you will need to fix up “Side Bar.sublime-settings” file and set "default_browser" to be "chrome".

I also recommend to learn this video tutorial on Sublime Text 2.

Windows Forms ProgressBar: Easiest way to start/stop marquee?

you can use a Timer (System.Windows.Forms.Timer).

Hook it's Tick event, advance then progress bar until it reaches the max value. when it does (hit the max) and you didn't finish the job, reset the progress bar value back to minimum.

...just like Windows Explorer :-)

Required attribute HTML5

Okay. The same time I was writing down my question one of my colleagues made me aware this is actually HTML5 behavior. See

Seems in HTML5 there is a new attribute "required". And Safari 5 already has an implementation for this attribute.

HashMaps and Null values?

Its a good programming practice to avoid having null values in a Map.

If you have an entry with null value, then it is not possible to tell whether an entry is present in the map or has a null value associated with it.

You can either define a constant for such cases (Example: String NOT_VALID = "#NA"), or you can have another collection storing keys which have null values.

Please check this link for more details.

Retrofit 2.0 how to get deserialised error response.body

Tested and works

 public BaseModel parse(Response<BaseModel> response , Retrofit retrofit){
            BaseModel error = null;
            Converter<ResponseBody, BaseModel> errorConverter =
                    retrofit.responseBodyConverter(BaseModel.class, new Annotation[0]);
            try {
                if (response.errorBody() != null) {
                    error = errorConverter.convert(response.errorBody());
            } catch (IOException e) {
            return error;

stop all instances of node.js server

Use the following command to kill and restart node server from batch file

    @echo off
cd "D:\sam\Projects\Node"
taskkill /IM node.exe -F
start /min cmd /C "node index.js"
goto :EOF

how to concat two columns into one with the existing column name in mysql?

Just Remove * from your select clause, and mention all column names explicitly and omit the FIRSTNAME column. After this write CONCAT(FIRSTNAME, ',', LASTNAME) AS FIRSTNAME. The above query will give you the only one FIRSTNAME column.

Using "super" in C++

I've quite often seen it used, sometimes as super_t, when the base is a complex template type (boost::iterator_adaptor does this, for example)

Some dates recognized as dates, some dates not recognized. Why?

It's not that hard...

Check out this forum post:

The steps in short:

  1. Select only the column of "dates"
  2. Click Data > Text to Columns
  3. Click Next
  4. Click Next
  5. In step 3 of the wizard, check "Date" under Col data format, then choose: "DMY" from the droplist.
  6. Click Finish

Removing header column from pandas dataframe

I had the same problem but solved it in this way:

df = pd.read_csv('your-array.csv', skiprows=[0])

Are lists thread-safe?

Lists themselves are thread-safe. In CPython the GIL protects against concurrent accesses to them, and other implementations take care to use a fine-grained lock or a synchronized datatype for their list implementations. However, while lists themselves can't go corrupt by attempts to concurrently access, the lists's data is not protected. For example:

L[0] += 1

is not guaranteed to actually increase L[0] by one if another thread does the same thing, because += is not an atomic operation. (Very, very few operations in Python are actually atomic, because most of them can cause arbitrary Python code to be called.) You should use Queues because if you just use an unprotected list, you may get or delete the wrong item because of race conditions.

Find files in a folder using Java

As @Clarke said, you can use to filter the file by specific condition.

As a complementary, I'd like to show how to use to search file in current directory and its subdirectory.

The common methods getTargetFiles and printFiles are used to search files and print them.

public class SearchFiles {

    //It's used in dfs
    private Map<String, Boolean> map = new HashMap<String, Boolean>();

    private File root;

    public SearchFiles(File root){
        this.root = root;

     * List eligible files on current path
     * @param directory
     *      The directory to be searched
     * @return
     *      Eligible files
    private String[] getTargetFiles(File directory){
        if(directory == null){
            return null;

        String[] files = directory.list(new FilenameFilter(){

            public boolean accept(File dir, String name) {
                // TODO Auto-generated method stub
                return name.startsWith("Temp") && name.endsWith(".txt");


        return files;

     * Print all eligible files
    private void printFiles(String[] targets){
        for(String target: targets){

I will demo how to use recursive, bfs and dfs to get the job done.


 * How many files in the parent directory and its subdirectory <br>
 * depends on how many files in each subdirectory and their subdirectory
private void recursive(File path){

    for(File file: path.listFiles()){

public static void main(String args[]){
    SearchFiles searcher = new SearchFiles(new File("C:\\example"));

Breadth First Search:

 * Search the node's neighbors firstly before moving to the next level neighbors
private void bfs(){
    if(root == null){

    Queue<File> queue = new LinkedList<File>();

        File node = queue.remove();
        File[] childs = node.listFiles(new FileFilter(){

            public boolean accept(File pathname) {
                // TODO Auto-generated method stub
                    return true;

                return false;


        if(childs != null){
            for(File child: childs){

public static void main(String args[]){
    SearchFiles searcher = new SearchFiles(new File("C:\\example"));

Depth First Search:

 * Search as far as possible along each branch before backtracking
private void dfs(){

    if(root == null){

    Stack<File> stack = new Stack<File>();
    map.put(root.getAbsolutePath(), true);
        File node = stack.peek();
        File child = getUnvisitedChild(node);

        if(child != null){
            map.put(child.getAbsolutePath(), true);


 * Get unvisited node of the node
private File getUnvisitedChild(File node){

    File[] childs = node.listFiles(new FileFilter(){

        public boolean accept(File pathname) {
            // TODO Auto-generated method stub
                return true;

            return false;


    if(childs == null){
        return null;

    for(File child: childs){

        if(map.containsKey(child.getAbsolutePath()) == false){
            map.put(child.getAbsolutePath(), false);

        if(map.get(child.getAbsolutePath()) == false){
            return child; 

    return null;

public static void main(String args[]){
    SearchFiles searcher = new SearchFiles(new File("C:\\example"));

Java: object to byte[] and byte[] to object converter (for Tokyo Cabinet)

public static byte[] serialize(Object obj) throws IOException {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    ObjectOutputStream os = new ObjectOutputStream(out);
    return out.toByteArray();
public static Object deserialize(byte[] data) throws IOException, ClassNotFoundException {
    ByteArrayInputStream in = new ByteArrayInputStream(data);
    ObjectInputStream is = new ObjectInputStream(in);
    return is.readObject();

Multipart forms from C# client

Building on dnolans example, this is the version I could actually get to work (there were some errors with the boundary, encoding wasn't set) :-)

To send the data:

HttpWebRequest oRequest = null;
oRequest = (HttpWebRequest)HttpWebRequest.Create("");
oRequest.ContentType = "multipart/form-data; boundary=" + PostData.boundary;
oRequest.Method = "POST";
PostData pData = new PostData();
Encoding encoding = Encoding.UTF8;
Stream oStream = null;

/* ... set the parameters, read files, etc. IE:
   pData.Params.Add(new PostDataParam("email", "[email protected]", PostDataParamType.Field));
   pData.Params.Add(new PostDataParam("fileupload", "filename.txt", "filecontents" PostDataParamType.File));

byte[] buffer = encoding.GetBytes(pData.GetPostData());

oRequest.ContentLength = buffer.Length;

oStream = oRequest.GetRequestStream();
oStream.Write(buffer, 0, buffer.Length);

HttpWebResponse oResponse = (HttpWebResponse)oRequest.GetResponse();

The PostData class should look like:

public class PostData
    // Change this if you need to, not necessary
    public static string boundary = "AaB03x";

    private List<PostDataParam> m_Params;

    public List<PostDataParam> Params
        get { return m_Params; }
        set { m_Params = value; }

    public PostData()
        m_Params = new List<PostDataParam>();

    /// <summary>
    /// Returns the parameters array formatted for multi-part/form data
    /// </summary>
    /// <returns></returns>
    public string GetPostData()
        StringBuilder sb = new StringBuilder();
        foreach (PostDataParam p in m_Params)
            sb.AppendLine("--" + boundary);

            if (p.Type == PostDataParamType.File)
                sb.AppendLine(string.Format("Content-Disposition: file; name=\"{0}\"; filename=\"{1}\"", p.Name, p.FileName));
                sb.AppendLine("Content-Type: application/octet-stream");
                sb.AppendLine(string.Format("Content-Disposition: form-data; name=\"{0}\"", p.Name));

        sb.AppendLine("--" + boundary + "--");

        return sb.ToString();

public enum PostDataParamType

public class PostDataParam
    public PostDataParam(string name, string value, PostDataParamType type)
        Name = name;
        Value = value;
        Type = type;

    public PostDataParam(string name, string filename, string value, PostDataParamType type)
        Name = name;
        Value = value;
        FileName = filename;
        Type = type;

    public string Name;
    public string FileName;
    public string Value;
    public PostDataParamType Type;

Long press on UITableView

Looks to be more efficient to add the recognizer directly to the cell as shown here:

Tap&Hold for TableView Cells, Then and Now

(scroll to the example at the bottom)

How to get current route in Symfony 2?

With Symfony 3.3, I have used this method and working fine.

I have 4 routes like

admin_category_index, admin_category_detail, admin_category_create, admin_category_update

And just one line make an active class for all routes.

<li  {% if app.request.get('_route') starts with 'admin_category' %} class="active"{% endif %}>
 <a href="{{ path('admin_category_index') }}">Product Categoires</a>

General guidelines to avoid memory leaks in C++

Great question!

if you are using c++ and you are developing real-time CPU-and-memory boud application (like games) you need to write your own Memory Manager.

I think the better you can do is merge some interesting works of various authors, I can give you some hint:

  • Fixed size allocator is heavily discussed, everywhere in the net

  • Small Object Allocation was introduced by Alexandrescu in 2001 in his perfect book "Modern c++ design"

  • A great advancement (with source code distributed) can be found in an amazing article in Game Programming Gem 7 (2008) named "High Performance Heap allocator" written by Dimitar Lazarov

  • A great list of resources can be found in this article

Do not start writing a noob unuseful allocator by yourself... DOCUMENT YOURSELF first.

How to get current class name including package name in Java?

use this.getClass().getName() to get packageName.className and use this.getClass().getSimpleName() to get only class name

How to save RecyclerView's scroll position using RecyclerView.State?

I wanted to save Recycler View's scroll position when navigating away from my list activity and then clicking the back button to navigate back. Many of the solutions provided for this problem were either much more complicated than needed or didn't work for my configuration, so I thought I'd share my solution.

First save your instance state in onPause as many have shown. I think it's worth emphasizing here that this version of onSaveInstanceState is a method from the RecyclerView.LayoutManager class.

private LinearLayoutManager mLayoutManager;
Parcelable state;

        public void onPause() {
            state = mLayoutManager.onSaveInstanceState();

The key to getting this to work properly is to make sure you call onRestoreInstanceState after you attach your adapter, as some have indicated in other threads. However the actual method call is much simpler than many have indicated.

private void someMethod() {

How do you determine what technology a website is built on?

Most ASP.NET sites are easy to identify from the .aspx in the URLs. There are also telltale signs in the HTML source, like a hidden form field named __VIEWSTATE or the WebResource.axd JavaScript. HTML elements will often have id attributes starting with something like _ctl0.

Rails sites will usually include stylesheets from /stylesheets and JavaScript files from /javascripts and each URL will usually have a query string containing a timestamp to thwart caching. Form fields will often follow the naming convention of model_name[attribute_name].

The matching wildcard is strict, but no declaration can be found for element 'tx:annotation-driven'

In my case this was actually a symptom of the server, hosted on AWS, lacking an IP for the external network. It would attempt to download namespaces from and fail to make a connection.

How to hide Android soft keyboard on EditText

Simply Use EditText.setFocusable(false); in activity

or use in xml


What is the best way to give a C# auto-property an initial value?

In the constructor. The constructor's purpose is to initialized it's data members.

How to set <Text> text to upper case in react native

iOS textTransform support has been added to react-native in 0.56 version. Android textTransform support has been added in 0.59 version. It accepts one of these options:

  • none
  • uppercase
  • lowercase
  • capitalize

The actual iOS commit, Android commit and documentation


  <Text style={{ textTransform: 'uppercase'}}>
    This text should be uppercased.
  <Text style={{ textTransform: 'capitalize'}}>
    Mixed:{' '}
    <Text style={{ textTransform: 'lowercase'}}>
      lowercase{' '}

How to count duplicate value in an array in javascript

uniqueCount = ["a","b","a","c","b","a","d","b","c","f","g","h","h","h","e","a"];
var count = {};
uniqueCount.forEach((i) => { count[i] = ++count[i]|| 1});

Are 64 bit programs bigger and faster than 32 bit versions?

In the specific case of x68 to x68_64, the 64 bit program will be about the same size, if not slightly smaller, use a bit more memory, and run faster. Mostly this is because x86_64 doesn't just have 64 bit registers, it also has twice as many. x86 does not have enough registers to make compiled languages as efficient as they could be, so x86 code spends a lot of instructions and memory bandwidth shifting data back and forth between registers and memory. x86_64 has much less of that, and so it takes a little less space and runs faster. Floating point and bit-twiddling vector instructions are also much more efficient in x86_64.

In general, though, 64 bit code is not necessarily any faster, and is usually larger, both for code and memory usage at runtime.

When do you use Git rebase instead of Git merge?

To complement my own answer mentioned by TSamper,

  • a rebase is quite often a good idea to do before a merge, because the idea is that you integrate in your branch Y the work of the branch B upon which you will merge.
    But again, before merging, you resolve any conflict in your branch (i.e.: "rebase", as in "replay my work in my branch starting from a recent point from the branch B).
    If done correctly, the subsequent merge from your branch to branch B can be fast-forward.

  • a merge directly impacts the destination branch B, which means the merges better be trivial, otherwise that branch B can be long to get back to a stable state (time for you solve all the conflicts)

the point of merging after a rebase?

In the case that I describe, I rebase B onto my branch, just to have the opportunity to replay my work from a more recent point from B, but while staying into my branch.
In this case, a merge is still needed to bring my "replayed" work onto B.

The other scenario (described in Git Ready for instance), is to bring your work directly in B through a rebase (which does conserve all your nice commits, or even give you the opportunity to re-order them through an interactive rebase).
In that case (where you rebase while being in the B branch), you are right: no further merge is needed:

A Git tree at default when we have not merged nor rebased


we get by rebasing:


That second scenario is all about: how do I get new-feature back into master.

My point, by describing the first rebase scenario, is to remind everyone that a rebase can also be used as a preliminary step to that (that being "get new-feature back into master").
You can use rebase to first bring master "in" the new-feature branch: the rebase will replay new-feature commits from the HEAD master, but still in the new-feature branch, effectively moving your branch starting point from an old master commit to HEAD-master.
That allows you to resolve any conflicts in your branch (meaning, in isolation, while allowing master to continue to evolve in parallel if your conflict resolution stage takes too long).
Then you can switch to master and merge new-feature (or rebase new-feature onto master if you want to preserve commits done in your new-feature branch).


  • "rebase vs. merge" can be viewed as two ways to import a work on, say, master.
  • But "rebase then merge" can be a valid workflow to first resolve conflict in isolation, then bring back your work.

numpy: most efficient frequency counts for unique values in an array

I was also interested in this, so I did a little performance comparison (using perfplot, a pet project of mine). Result:

y = np.bincount(a)
ii = np.nonzero(y)[0]
out = np.vstack((ii, y[ii])).T

is by far the fastest. (Note the log-scaling.)

enter image description here

Code to generate the plot:

import numpy as np
import pandas as pd
import perfplot
from scipy.stats import itemfreq

def bincount(a):
    y = np.bincount(a)
    ii = np.nonzero(y)[0]
    return np.vstack((ii, y[ii])).T

def unique(a):
    unique, counts = np.unique(a, return_counts=True)
    return np.asarray((unique, counts)).T

def unique_count(a):
    unique, inverse = np.unique(a, return_inverse=True)
    count = np.zeros(len(unique),, inverse, 1)
    return np.vstack((unique, count)).T

def pandas_value_counts(a):
    out = pd.value_counts(pd.Series(a))
    out = np.stack([out.keys().values, out.values]).T
    return out
    setup=lambda n: np.random.randint(0, 1000, n),
    kernels=[bincount, unique, itemfreq, unique_count, pandas_value_counts],
    n_range=[2 ** k for k in range(26)],

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

  1. Pick any <remote_name> you'd like to use (feel free to use origin and skip step 1.)
  2. git remote add <remote_name> <remote_url>
  3. git fetch <remote_name> <branch>
  4. Pick any <your_local_branch_name> you'd like to use. Could be the same as <branch>.
  5. git checkout <remote_name>/<branch> -b <your_local_branch_name>

Hope that helps!

Hiding a form and showing another when a button is clicked in a Windows Forms application

Anything after Application.Run( ) will only be executed when the main form closes.

What you could do is handle the VisibleChanged event as follows:

static Form1 form1;
static Form2 form2;

static void Main()

    form2 = new Form2();
    form1 = new Form1();
    form1.VisibleChanged += OnForm1Changed;


static void OnForm1Changed( object sender, EventArgs args )
    if ( !form1.Visible )
        form2.Show( );

Counting the number of option tags in a select tag in jQuery

Ok, i had a few problems because i was inside a

$('.my-dropdown').live('click', function(){  

I had multiples inside my page that's why i used a class.

My drop down was filled automatically by a ajax request when i clicked it, so i only had the element $(this)


I had to do:

$('.my-dropdown').live('click', function(){
  total_tems = $(this).find('option').length;

Is there a "not equal" operator in Python?

There are two operators in Python for the "not equal" condition -

a.) != If values of the two operands are not equal, then the condition becomes true. (a != b) is true.

b.) <> If values of the two operands are not equal, then the condition becomes true. (a <> b) is true. This is similar to the != operator.

SOAP request in PHP with CURL

Tested and working!

  • with https, user & password

     //Data, connection, auth
     $dataFromTheForm = $_POST['fieldName']; // request data from the form
     $soapUrl = ""; // asmx URL of WSDL
     $soapUser = "username";  //  username
     $soapPassword = "password"; // password
     // xml post structure
     $xml_post_string = '<?xml version="1.0" encoding="utf-8"?>
                         <soap:Envelope xmlns:xsi="" xmlns:xsd="" xmlns:soap="">
                             <GetItemPrice xmlns=""> // xmlns value to be set to your WSDL URL
                             </GetItemPrice >
                         </soap:Envelope>';   // data from the form, e.g. some ID number
        $headers = array(
                     "Content-type: text/xml;charset=\"utf-8\"",
                     "Accept: text/xml",
                     "Cache-Control: no-cache",
                     "Pragma: no-cache",
                     "Content-length: ".strlen($xml_post_string),
                 ); //SOAPAction: your op URL
         $url = $soapUrl;
         // PHP cURL  for https connection with auth
         $ch = curl_init();
         curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
         curl_setopt($ch, CURLOPT_URL, $url);
         curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
         curl_setopt($ch, CURLOPT_USERPWD, $soapUser.":".$soapPassword); // username and password - declared at the top of the doc
         curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
         curl_setopt($ch, CURLOPT_TIMEOUT, 10);
         curl_setopt($ch, CURLOPT_POST, true);
         curl_setopt($ch, CURLOPT_POSTFIELDS, $xml_post_string); // the SOAP request
         curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
         // converting
         $response = curl_exec($ch); 
         // converting
         $response1 = str_replace("<soap:Body>","",$response);
         $response2 = str_replace("</soap:Body>","",$response1);
         // convertingc to XML
         $parser = simplexml_load_string($response2);
         // user $parser to get your data out of XML response and to display it. 

How to find an object in an ArrayList by property

Following with Oleg answer, if you want to find ALL objects in a List filtered by a property, you could do something like:

//Search into a generic list ALL items with a generic property
public final class SearchTools {
       public static <T> List<T> findByProperty(Collection<T> col, Predicate<T> filter) {
           List<T> filteredList = (List<T>);
           return filteredList;

//Search in the list "listItems" ALL items of type "Item" with the specific property "iD_item=itemID"
public static final class ItemTools {
         public static List<Item> findByItemID(Collection<Item> listItems, String itemID) {
             return SearchTools.findByProperty(listItems, item -> itemID.equals(item.getiD_Item()));

and similarly if you want to filter ALL items in a HashMap with a certain Property

//Search into a MAP ALL items with a given property
public final class SearchTools {
       public static <T> HashMap<String,T> filterByProperty(HashMap<String,T> completeMap, Predicate<? super Map.Entry<String,T>> filter) {
           HashMap<String,T> filteredList = (HashMap<String,T>) completeMap.entrySet().stream()
                                .collect(Collectors.toMap(map -> map.getKey(), map -> map.getValue()));
           return filteredList;

     //Search into the MAP ALL items with specific properties
public static final class ItemTools {

        public static HashMap<String,Item> filterByParentID(HashMap<String,Item> mapItems, String parentID) {
            return SearchTools.filterByProperty(mapItems, mapItem -> parentID.equals(mapItem.getValue().getiD_Parent()));

        public static HashMap<String,Item> filterBySciName(HashMap<String,Item> mapItems, String sciName) {
            return SearchTools.filterByProperty(mapItems, mapItem -> sciName.equals(mapItem.getValue().getSciName()));

Injecting @Autowired private field during testing

I believe in order to have auto-wiring work on your MyLauncher class (for myService), you will need to let Spring initialize it instead of calling the constructor, by auto-wiring myLauncher. Once that is being auto-wired (and myService is also getting auto-wired), Spring (1.4.0 and up) provides a @MockBean annotation you can put in your test. This will replace a matching single beans in context with a mock of that type. You can then further define what mocking you want, in a @Before method.

public class MyLauncherTest
    private MyService myService;

    private MyLauncher myLauncher;

    private void setupMockBean() {
        doReturn("Some Value").when(myService).someStringMethod();

    public void someTest() {

Your MyLauncher class can then remain unmodified, and your MyService bean will be a mock whose methods return values as you defined:

public class MyLauncher {
    MyService myService;

    public void doSomething() {

    //other methods

A couple advantages of this over other methods mentioned is that:

  1. You don't need to manually inject myService.
  2. You don't need use the Mockito runner or rules.

jQuery’s .bind() vs. .on()

From the jQuery documentation:

As of jQuery 1.7, the .on() method is the preferred method for attaching event handlers to a document. For earlier versions, the .bind() method is used for attaching an event handler directly to elements. Handlers are attached to the currently selected elements in the jQuery object, so those elements must exist at the point the call to .bind() occurs. For more flexible event binding, see the discussion of event delegation in .on() or .delegate().

CronJob not running

Sometimes the command that cron needs to run is in a directory where cron has no access, typically on systems where users' home directories' permissions are 700 and the command is in that directory.

How to get the root dir of the Symfony2 application?

UPDATE 2018-10-21:

As of this week, getRootDir() was deprecated. Please use getProjectDir() instead, as suggested in the comment section by Muzaraf Ali.


Use this:


And if you want the web root:

$this->get('kernel')->getRootDir() . '/../web' . $this->getRequest()->getBasePath();

this will work from controller action method...

EDIT: As for the services, I think the way you did it is as clean as possible, although I would pass complete kernel service as an argument... but this will also do the trick...

Return string without trailing slash

I'd use a regular expression:

function someFunction(site)
// if site has an end slash (like:,
// then remove it and return the site without the end slash
return site.replace(/\/$/, '') // Match a forward slash / at the end of the string ($)

You'll want to make sure that the variable site is a string, though.

Extract digits from string - StringUtils Java

Extending the best answer for finding floating point numbers

       String str="2.53GHz";
       String decimal_values= str.replaceAll("[^0-9\\.]", "");