Programs & Examples On #Sql injection

SQL injection is a code injection technique, used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker)

How does a PreparedStatement avoid or prevent SQL injection?

The SQL used in a PreparedStatement is precompiled on the driver. From that point on, the parameters are sent to the driver as literal values and not executable portions of SQL; thus no SQL can be injected using a parameter. Another beneficial side effect of PreparedStatements (precompilation + sending only parameters) is improved performance when running the statement multiple times even with different values for the parameters (assuming that the driver supports PreparedStatements) as the driver does not have to perform SQL parsing and compilation each time the parameters change.

Are PDO prepared statements sufficient to prevent SQL injection?

Prepared statements / parameterized queries are generally sufficient to prevent 1st order injection on that statement*. If you use un-checked dynamic sql anywhere else in your application you are still vulnerable to 2nd order injection.

2nd order injection means data has been cycled through the database once before being included in a query, and is much harder to pull off. AFAIK, you almost never see real engineered 2nd order attacks, as it is usually easier for attackers to social-engineer their way in, but you sometimes have 2nd order bugs crop up because of extra benign ' characters or similar.

You can accomplish a 2nd order injection attack when you can cause a value to be stored in a database that is later used as a literal in a query. As an example, let's say you enter the following information as your new username when creating an account on a web site (assuming MySQL DB for this question):

' + (SELECT UserName + '_' + Password FROM Users LIMIT 1) + '

If there are no other restrictions on the username, a prepared statement would still make sure that the above embedded query doesn't execute at the time of insert, and store the value correctly in the database. However, imagine that later the application retrieves your username from the database, and uses string concatenation to include that value a new query. You might get to see someone else's password. Since the first few names in users table tend to be admins, you may have also just given away the farm. (Also note: this is one more reason not to store passwords in plain text!)

We see, then, that prepared statements are enough for a single query, but by themselves they are not sufficient to protect against sql injection attacks throughout an entire application, because they lack a mechanism to enforce all access to a database within an application uses safe code. However, used as part of good application design — which may include practices such as code review or static analysis, or use of an ORM, data layer, or service layer that limits dynamic sql — prepared statements are the primary tool for solving the Sql Injection problem. If you follow good application design principles, such that your data access is separated from the rest of your program, it becomes easy to enforce or audit that every query correctly uses parameterization. In this case, sql injection (both first and second order) is completely prevented.

*It turns out that MySql/PHP are (okay, were) just dumb about handling parameters when wide characters are involved, and there is still a rare case outlined in the other highly-voted answer here that can allow injection to slip through a parameterized query.

How can prepared statements protect from SQL injection attacks?

I read through the answers and still felt the need to stress the key point which illuminates the essence of Prepared Statements. Consider two ways to query one's database where user input is involved:

Naive Approach

One concatenates user input with some partial SQL string to generate a SQL statement. In this case the user can embed malicious SQL commands, which will then be sent to the database for execution.

String SQLString = "SELECT * FROM CUSTOMERS WHERE NAME='"+userInput+"'"

For example, malicious user input can lead to SQLString being equal to "SELECT * FROM CUSTOMERS WHERE NAME='James';DROP TABLE CUSTOMERS;'

Due to the malicious user, SQLString contains 2 statements, where the 2nd one ("DROP TABLE CUSTOMERS") will cause harm.

Prepared Statements

In this case, due to the separation of the query & data, the user input is never treated as a SQL statement, and thus is never executed. It is for this reason, that any malicious SQL code injected would cause no harm. So the "DROP TABLE CUSTOMERS" would never be executed in the case above.

In a nutshell, with prepared statements malicious code introduced via user input will not be executed!

How does the SQL injection from the "Bobby Tables" XKCD comic work?

The '); ends the query, it doesn't start a comment. Then it drops the students table and comments the rest of the query that was supposed to be executed.

Found 'OR 1=1/* sql injection in my newsletter database

Its better if you use validation code to the users input for making it restricted to use symbols and part of code in your input form. If you embeed php in html code your php code have to become on the top to make sure that it is not ignored as comment if a hacker edit the page and add /* in your html code

Why do we always prefer using parameters in SQL statements?

In Sql when any word contain @ sign it means it is variable and we use this variable to set value in it and use it on number area on the same sql script because it is only restricted on the single script while you can declare lot of variables of same type and name on many script. We use this variable in stored procedure lot because stored procedure are pre-compiled queries and we can pass values in these variable from script, desktop and websites for further information read Declare Local Variable, Sql Stored Procedure and sql injections.

Also read Protect from sql injection it will guide how you can protect your database.

Hope it help you to understand also any question comment me.

Preventing SQL injection in Node.js

The library has a section in the readme about escaping. It's Javascript-native, so I do not suggest switching to node-mysql-native. The documentation states these guidelines for escaping:

Edit: node-mysql-native is also a pure-Javascript solution.

  • Numbers are left untouched
  • Booleans are converted to true / false strings
  • Date objects are converted to YYYY-mm-dd HH:ii:ss strings
  • Buffers are converted to hex strings, e.g. X'0fa5'
  • Strings are safely escaped
  • Arrays are turned into list, e.g. ['a', 'b'] turns into 'a', 'b'
  • Nested arrays are turned into grouped lists (for bulk inserts), e.g. [['a', 'b'], ['c', 'd']] turns into ('a', 'b'), ('c', 'd')
  • Objects are turned into key = 'val' pairs. Nested objects are cast to strings.
  • undefined / null are converted to NULL
  • NaN / Infinity are left as-is. MySQL does not support these, and trying to insert them as values will trigger MySQL errors until they implement support.

This allows for you to do things like so:

var userId = 5;
var query = connection.query('SELECT * FROM users WHERE id = ?', [userId], function(err, results) {
  //query.sql returns SELECT * FROM users WHERE id = '5'

As well as this:

var post  = {id: 1, title: 'Hello MySQL'};
var query = connection.query('INSERT INTO posts SET ?', post, function(err, result) {
  //query.sql returns INSERT INTO posts SET `id` = 1, `title` = 'Hello MySQL'

Aside from those functions, you can also use the escape functions:


To escape query identifiers:


And as a response to your comment on prepared statements:

From a usability perspective, the module is great, but it has not yet implemented something akin to PHP's Prepared Statements.

The prepared statements are on the todo list for this connector, but this module at least allows you to specify custom formats that can be very similar to prepared statements. Here's an example from the readme:

connection.config.queryFormat = function (query, values) {
  if (!values) return query;
  return query.replace(/\:(\w+)/g, function (txt, key) {
    if (values.hasOwnProperty(key)) {
      return this.escape(values[key]);
    return txt;

This changes the query format of the connection so you can use queries like this:

connection.query("UPDATE posts SET title = :title", { title: "Hello MySQL" });
//equivalent to
connection.query("UPDATE posts SET title = " + mysql.escape("Hello MySQL");

SQL injection that gets around mysql_real_escape_string()

Well, there's nothing really that can pass through that, other than % wildcard. It could be dangerous if you were using LIKE statement as attacker could put just % as login if you don't filter that out, and would have to just bruteforce a password of any of your users. People often suggest using prepared statements to make it 100% safe, as data can't interfere with the query itself that way. But for such simple queries it probably would be more efficient to do something like $login = preg_replace('/[^a-zA-Z0-9_]/', '', $login);

What are good ways to prevent SQL injection?

My answer is quite easy:

Use Entity Framework for communication between C# and your SQL database. That will make parameterized SQL strings that isn't vulnerable to SQL injection.

As a bonus, it's very easy to work with as well.

Java - escape string to prevent SQL injection

Prepared Statements are the best solution, but if you really need to do it manually you could also use the StringEscapeUtils class from the Apache Commons-Lang library. It has an escapeSql(String) method, which you can use:

import org.apache.commons.lang.StringEscapeUtils; … String escapedSQL = StringEscapeUtils.escapeSql(unescapedSQL);

How can I sanitize user input with PHP?

No. You can't generically filter data without any context of what it's for. Sometimes you'd want to take a SQL query as input and sometimes you'd want to take HTML as input.

You need to filter input on a whitelist -- ensure that the data matches some specification of what you expect. Then you need to escape it before you use it, depending on the context in which you are using it.

The process of escaping data for SQL - to prevent SQL injection - is very different from the process of escaping data for (X)HTML, to prevent XSS.

WARNING: Can't verify CSRF token authenticity rails


I missed the following line in my application.js

//= require jquery_ujs

I replaced it and its working..

======= UPDATED =========

After 5 years, I am back with Same error, now I have brand new Rails 5.1.6, and I found this post again. Just like circle of life.

Now what was the issue is: Rails 5.1 removed support for jquery and jquery_ujs by default, and added

//= require rails-ujs in application.js

It does the following things:

  1. force confirmation dialogs for various actions;
  2. make non-GET requests from hyperlinks;
  3. make forms or hyperlinks submit data asynchronously with Ajax;
  4. have submit buttons become automatically disabled on form submit to prevent double-clicking. (from:

But why is it not including the csrf token for ajax request? If anyone know about this in detail just comment me. I appreciate that.

Anyway I added the following in my custom js file to make it work (Thanks for other answers to help me reach this code):

$( document ).ready(function() {
    headers: {
      'X-CSRF-Token': Rails.csrfToken()

how to make a whole row in a table clickable as a link?

  <tr tabindex="0" onmousedown="window.location='#';">

Replace # with the url, tabindex="0" makes any element focusable

How to call a VbScript from a Batch File without opening an additional command prompt

If you want to fix vbs associations type

regsvr32 vbscript.dll
regsvr32 jscript.dll
regsvr32 wshext.dll
regsvr32 wshom.ocx
regsvr32 wshcon.dll
regsvr32 scrrun.dll

Also if you can't use vbs due to management then convert your script to a program which is designed to be easy, is easy, and takes 5 minutes.

Big difference is functions and subs are both called using brackets rather than just functions.

So the compilers are installed on all computers with .NET installed.

See this article here on how to make a .NET exe. Note the sample is for a scripting host. You can't use this, you have to put your vbs code in as .NET code.

How can I convert a VBScript to an executable (EXE) file?

how to force maven to update local repo

try using -U (aka --update-snapshots) when you run maven

And make sure the dependency definition is correct

SQL Server : login success but "The database [dbName] is not accessible. (ObjectExplorer)"

If you are using Sql Management Studio, just start it as Administrator.

Right click->Run as Administrator

How to select distinct rows in a datatable and store into an array

Following single line of code will avoid the duplicate rows of a DataTable:

dataTable.DefaultView.ToTable(true, "employeeid");


  • first parameter in ToTable() is a boolean which indicates whether you want distinct rows or not.

  • second parameter in the ToTable() is the column name based on which we have to select distinct rows. Only these columns will be in the returned datatable.

The same can be done from a DataSet, by accessing a specific DataTable:

dataSet.Tables["Employee"].DefaultView.ToTable(true, "employeeid");

Multiplying Two Columns in SQL Server


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

How do I copy folder with files to another folder in Unix/Linux?

The option you're looking for is -R.

cp -R path_to_source path_to_destination/
  • If destination doesn't exist, it will be created.
  • -R means copy directories recursively. You can also use -r since it's case-insensitive.
  • Note the nuances with adding the trailing / as per @muni764's comment.

Strange Jackson exception being thrown when serializing Hibernate object

It's not ideal, but you could disable Jackson's auto-discovery of JSON properties, using @JsonAutoDetect at the class level. This would prevent it from trying to handle the Javassist stuff (and failing).

This means that you then have to annotate each getter manually (with @JsonProperty), but that's not necessarily a bad thing, since it keeps things explicit.

XmlDocument - load from string?

XmlDocument doc = new XmlDocument();

Where str is your XML string. See the MSDN article for more info.

How can I send and receive WebSocket messages on the server side?

C# Implementation

Browser -> Server

    private String DecodeMessage(Byte[] bytes)
        String incomingData = String.Empty;
        Byte secondByte = bytes[1];
        Int32 dataLength = secondByte & 127;
        Int32 indexFirstMask = 2;
        if (dataLength == 126)
            indexFirstMask = 4;
        else if (dataLength == 127)
            indexFirstMask = 10;

        IEnumerable<Byte> keys = bytes.Skip(indexFirstMask).Take(4);
        Int32 indexFirstDataByte = indexFirstMask + 4;

        Byte[] decoded = new Byte[bytes.Length - indexFirstDataByte];
        for (Int32 i = indexFirstDataByte, j = 0; i < bytes.Length; i++, j++)
            decoded[j] = (Byte)(bytes[i] ^ keys.ElementAt(j % 4));

        return incomingData = Encoding.UTF8.GetString(decoded, 0, decoded.Length);

Server -> Browser

    private static Byte[] EncodeMessageToSend(String message)
        Byte[] response;
        Byte[] bytesRaw = Encoding.UTF8.GetBytes(message);
        Byte[] frame = new Byte[10];

        Int32 indexStartRawData = -1;
        Int32 length = bytesRaw.Length;

        frame[0] = (Byte)129;
        if (length <= 125)
            frame[1] = (Byte)length;
            indexStartRawData = 2;
        else if (length >= 126 && length <= 65535)
            frame[1] = (Byte)126;
            frame[2] = (Byte)((length >> 8) & 255);
            frame[3] = (Byte)(length & 255);
            indexStartRawData = 4;
            frame[1] = (Byte)127;
            frame[2] = (Byte)((length >> 56) & 255);
            frame[3] = (Byte)((length >> 48) & 255);
            frame[4] = (Byte)((length >> 40) & 255);
            frame[5] = (Byte)((length >> 32) & 255);
            frame[6] = (Byte)((length >> 24) & 255);
            frame[7] = (Byte)((length >> 16) & 255);
            frame[8] = (Byte)((length >> 8) & 255);
            frame[9] = (Byte)(length & 255);

            indexStartRawData = 10;

        response = new Byte[indexStartRawData + length];

        Int32 i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
            response[reponseIdx] = frame[i];

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
            response[reponseIdx] = bytesRaw[i];

        return response;

String to HtmlDocument

you could get a htmldocument by:

 System.Net.WebClient wc = new System.Net.WebClient();

 System.IO.Stream stream = wc.OpenRead(url);
 System.IO.StreamReader reader = new System.IO.StreamReader(stream);
 string s = reader.ReadToEnd();

 HtmlDocument doc = new HtmlDocument();

so you have getbiyid and getbyname ... but any further you'd better of with
HTML Agility Pack as suggested . f.e you can do: doc.DocumentNode.SelectNodes(xpathselector) or regex to parse the doc ..

btw: why not regex ? . its soo cool if you can use it right... but xpath is also very mighty ... so "choose your poison"


How do I use T-SQL's Case/When?

If logical test is against a single column then you could use something like

USE AdventureWorks2012;  
SELECT   ProductNumber, Category =  
      CASE ProductLine  
         WHEN 'R' THEN 'Road'  
         WHEN 'M' THEN 'Mountain'  
         WHEN 'T' THEN 'Touring'  
         WHEN 'S' THEN 'Other sale items'  
         ELSE 'Not for sale'  
FROM Production.Product  
ORDER BY ProductNumber;  

More information -

Twitter Bootstrap - how to center elements horizontally or vertically

You may directly write into your css file like this :

.content {_x000D_
  position: absolute;_x000D_
  top: 50%;_x000D_
  transform: translate(-50%,-50%);_x000D_
<div class = "content" >_x000D_
   <p> some text </p>_x000D_

PUT and POST getting 405 Method Not Allowed Error for Restful Web Services

The problem is that POST method is forbidden for Nginx server's static files requests. Here is the workaround:

# Pass 405 as 200 for requested address:

server {
listen       80;
server_name  localhost;

location / {
    root   html;
    index  index.html index.htm;

error_page  404     /404.html;
error_page  403     /403.html;

error_page  405     =200 $uri;

If using proxy:

# If Nginx is like proxy for Apache:

error_page 405 =200 @405; 

location @405 { 
    root /htdocs; 
    proxy_pass http://localhost:8080; 

If using FastCGI:

location ~\.php(.*) {
fastcgi_split_path_info ^(.+\.php)(.*)$;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO $fastcgi_path_info;
fastcgi_param PATH_TRANSLATED $document_root$fastcgi_path_info;
include /etc/nginx/fastcgi_params;

Browsers usually use GET, so you can use online tools like ApiTester to test your requests.


How I add Headers to http.get or in Typescript and angular 2?

This way I was able to call MyService

private REST_API_SERVER = 'http://localhost:4040/abc';
public sendGetRequest() {
   var myFormData = { email: '[email protected]', password: '123' };
   const headers = new HttpHeaders();
   headers.append('Content-Type', 'application/json');
  .post(this.REST_API_SERVER, myFormData, {
    headers: headers,
  .subscribe((data) => {
    console.log("i'm from service............", data, myFormData, headers);
    return data;

How to use unicode characters in Windows command line?


chcp 65001

which will change the code page to UTF-8. Also, you need to use Lucida console fonts.

Disable dragging an image from an HTML page

Great solution, had one small issue with conflicts, If anyone else has conflict from other js library simply enable no conflict like so.

var $j = jQuery.noConflict();$j('img').bind('dragstart', function(event) { event.preventDefault(); });

Hope this helps someone out.

how to add json library

You can also install simplejson.

If you have pip (see as your Python package manager you can install simplejson with:

 pip install simplejson

This is similar to the comment of installing with easy_install, but I prefer pip to easy_install as you can easily uninstall in pip with "pip uninstall package".

Java ArrayList clear() function

Source code of clear shows the reason why the newly added data gets the first position.

 public void clear() {

    // Let gc do its work
    for (int i = 0; i < size; i++)
        elementData[i] = null;

    size = 0;

clear() is faster than removeAll() by the way, first one is O(n) while the latter is O(n_2)

How to retrieve form values from HTTPPOST, dictionary or?

You could have your controller action take an object which would reflect the form input names and the default model binder will automatically create this object for you:

public ActionResult SubmitAction(SomeModel model)
    var value1 = model.SimpleProp1;
    var value2 = model.SimpleProp2;
    var value3 = model.ComplexProp1.SimpleProp1;

    ... return something ...

Another (obviously uglier) way is:

public ActionResult SubmitAction()
    var value1 = Request["SimpleProp1"];
    var value2 = Request["SimpleProp2"];
    var value3 = Request["ComplexProp1.SimpleProp1"];

    ... return something ...

Text File Parsing in Java

I'm not sure how efficient it is memory-wise, but my first approach would be using a Scanner as it is incredibly easy to use:

File file = new File("/path/to/my/file.txt");
Scanner input = new Scanner(file);

while(input.hasNext()) {
    String nextToken =;
    //or to process line by line
    String nextLine = input.nextLine();


Check the API for how to alter the delimiter it uses to split tokens.

Android Design Support Library expandable Floating Action Button(FAB) menu

Got a better approach to implement the animating FAB menu without using any library or to write huge xml code for animations. hope this will help in future for someone who needs a simple way to implement this.

Just using animate().translationY() function, you can animate any view up or down just I did in my below code, check complete code in github. In case you are looking for the same code in kotlin, you can checkout the kotlin code repo Animating FAB Menu.

first define all your FAB at same place so they overlap each other, remember on top the FAB should be that you want to click and to show other. eg:

    app:srcCompat="@android:drawable/ic_btn_speak_now" />

    app:srcCompat="@android:drawable/ic_menu_camera" />

    app:srcCompat="@android:drawable/ic_dialog_map" />

    app:srcCompat="@android:drawable/ic_dialog_email" />

Now in your java class just define all your FAB and perform the click like shown below:

 FloatingActionButton fab = (FloatingActionButton) findViewById(;
    fab1 = (FloatingActionButton) findViewById(;
    fab2 = (FloatingActionButton) findViewById(;
    fab3 = (FloatingActionButton) findViewById(;
    fab.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {

Use the animation().translationY() to animate your FAB,I prefer you to use the attribute of this method in DP since only using an int will effect the display compatibility with higher resolution or lower resolution. as shown below:

 private void showFABMenu(){

private void closeFABMenu(){

Now define the above mentioned dimension inside res->values->dimens.xml as shown below:

    <dimen name="standard_55">55dp</dimen>
<dimen name="standard_105">105dp</dimen>
<dimen name="standard_155">155dp</dimen>

That's all hope this solution will help the people in future, who are searching for simple solution.


If you want to add label over the FAB then simply take a horizontal LinearLayout and put the FAB with textview as label, and animate the layouts if find any issue doing this, you can check my sample code in github, I have handelled all backward compatibility issues in that sample code. check my sample code for FABMenu in Github

to close the FAB on Backpress, override onBackPress() as showen below:

public void onBackPressed() {

The Screenshot have the title as well with the FAB,because I take it from my sample app present ingithub

enter image description here

enum to string in modern C++11 / C++14 / C++17 and future C++20

My solution, using a preprocessor define.

You can check this code on

#include <iostream>
#include <stdexcept>
#include <regex>

typedef std::string String;
using namespace std::literals::string_literals;

class Strings
    static String TrimStart(const std::string& data)
        String s = data;
        s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch) {
            return !std::isspace(ch);
        return s;

    static String TrimEnd(const std::string& data)
        String s = data;
        s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch) {
            return !std::isspace(ch);
        return s;

    static String Trim(const std::string& data)
        return TrimEnd(TrimStart(data));

    static String Replace(const String& data, const String& toFind, const String& toReplace)
        String result = data;
        size_t pos = 0;
        while ((pos = result.find(toFind, pos)) != String::npos)
            result.replace(pos, toFind.length(), toReplace);
            pos += toReplace.length();
            pos = result.find(toFind, pos);
        return result;


static String Nameof(const String& name)
    std::smatch groups;
    String str = Strings::Trim(name);
    if (std::regex_match(str, groups, std::regex(u8R"(^&?([_a-zA-Z]\w*(->|\.|::))*([_a-zA-Z]\w*)$)")))
        if (groups.size() == 4)
            return groups[3];
    throw std::invalid_argument(Strings::Replace(u8R"(nameof(#). Invalid identifier "#".)", u8"#", name));

#define nameof(name) Nameof(u8## #name ## s)
#define cnameof(name) Nameof(u8## #name ## s).c_str()

enum TokenType {

struct MyClass
    enum class MyEnum : char {
        AAA = -8,
        BBB = '8',
        CCC = AAA + BBB

int main() {
    String greetings = u8"Hello"s;
    std::cout << nameof(COMMA) << std::endl;
    std::cout << nameof(TokenType::PERIOD) << std::endl;
    std::cout << nameof(TokenType::Q_MARK) << std::endl;
    std::cout << nameof(int) << std::endl;
    std::cout << nameof(std::string) << std::endl;
    std::cout << nameof(Strings) << std::endl;
    std::cout << nameof(String) << std::endl;
    std::cout << nameof(greetings) << std::endl;
    std::cout << nameof(&greetings) << std::endl;
    std::cout << nameof(greetings.c_str) << std::endl;
    std::cout << nameof(std::string::npos) << std::endl;
    std::cout << nameof(MyClass::MyEnum::AAA) << std::endl;
    std::cout << nameof(MyClass::MyEnum::BBB) << std::endl;
    std::cout << nameof(MyClass::MyEnum::CCC) << std::endl;

    return 0;





Visual C++

enter image description here

Implicit type conversion rules in C++ operators

In C++ operators (for POD types) always act on objects of the same type.
Thus if they are not the same one will be promoted to match the other.
The type of the result of the operation is the same as operands (after conversion).

If either is      long          double the other is promoted to      long          double
If either is                    double the other is promoted to                    double
If either is                    float  the other is promoted to                    float
If either is long long unsigned int    the other is promoted to long long unsigned int
If either is long long          int    the other is promoted to long long          int
If either is long      unsigned int    the other is promoted to long      unsigned int
If either is long               int    the other is promoted to long               int
If either is           unsigned int    the other is promoted to           unsigned int
If either is                    int    the other is promoted to                    int
Both operands are promoted to int

Note. The minimum size of operations is int. So short/char are promoted to int before the operation is done.

In all your expressions the int is promoted to a float before the operation is performed. The result of the operation is a float.

int + float =>  float + float = float
int * float =>  float * float = float
float * int =>  float * float = float
int / float =>  float / float = float
float / int =>  float / float = float
int / int                     = int
int ^ float =>  <compiler error>

White space showing up on right side of page when background image should extend full length of page

The problem is in the file :

style.css - line 721

#sub_footer {
    background: url("../images/exterior/sub_footer.png") repeat-x;
    background: -moz-linear-gradient(0% 100% 90deg,#102c40, #091925);
    background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#091925), to(#102c40));
    -moz-box-shadow: 3px 3px 4px #999999;
    -webkit-box-shadow: 3px 3px 4px #999999;
    box-shadow: 3px 3px 4px #999999;

remove the lines :

-moz-box-shadow: 3px 3px 4px #999999;
-webkit-box-shadow: 3px 3px 4px #999999;
box-shadow: 3px 3px 4px #999999; 

This basically gives a shadow gradient only to the footer. In Firefox, it is the first line that is causing the problem.

How to fix docker: Got permission denied issue

To fix that issue, I searched where is my docker and docker-compose installed. In my case, docker was installed in /usr/bin/docker and docker-compose was installed in /usr/local/bin/docker-compose path. Then, I write this in my terminal:

To docker:

sudo chmod +x /usr/bin/docker

To docker-compose:

sudo chmod +x /usr/local/bin/docker-compose

Now I don't need write in my commands docker the word sudo



The best solution of this issue was commented by @mkasberg. I quote comment:

That might work, you might run into issues down the road. Also, it's a security vulnerability. You'd be better off just adding yourself to the docker group, as the docs say. sudo groupadd docker, sudo usermod -aG docker $USER. Docs:

Thanks a lot!

How to get the EXIF data from a file using C#

You can use TagLib# which is used by applications such as F-Spot. Besides Exif, it will read a good amount of metadata formats for image, audio and video.

I also like ExifUtils API but it is buggy and is not actively developed.

TypeScript error: Type 'void' is not assignable to type 'boolean'

Your code is passing a function as an argument to find. That function takes an element argument (of type Conversation) and returns void (meaning there is no return value). TypeScript describes this as (element: Conversation) => void'

What TypeScript is saying is that the find function doesn't expect to receive a function that takes a Conversation and returns void. It expects a function that takes a Conversations, a number and a Conversation array, and that this function should return a boolean.

So bottom line is that you either need to change your code to pass in the values to find correctly, or else you need to provide an overload to the definition of find in your definition file that accepts a Conversation and returns void.

How can I mock an ES6 module import using Jest?

The claims that you have to mock it at the top of your file are false.

Mock a named ES Import:

// import the named module
import { useWalkthroughAnimations } from '../hooks/useWalkthroughAnimations';

// mock the file and its named export
jest.mock('../hooks/useWalkthroughAnimations', () => ({
  useWalkthroughAnimations: jest.fn()

// do whatever you need to do with your mocked function
useWalkthroughAnimations.mockReturnValue({ pageStyles, goToNextPage, page });

javascript convert int to float

JavaScript only has a Number type that stores floating point values.

There is no int.


If you want to format the number as a string with two digits after the decimal point use:


Angular 4 default radio button checked by default

We can use [(ngModel)] in following way and have a value selection variable radioSelected

Example tutorial

Demo Link


  <div class="text-center mt-5">
  <h4>Selected value is {{}}</h4>

    <ul class="list-group">
          <li class="list-group-item"  *ngFor="let item of itemsList">
            <input type="radio" [(ngModel)]="radioSelected" name="list_name" value="{{item.value}}" (change)="onItemChange(item)"/> 





  import {Item} from '../app/item';
  import {ITEMS} from '../app/mock-data';

    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
  export class AppComponent {
    title = 'app';
    itemsList: Item[] = ITEMS;

      constructor() {
        this.itemsList = ITEMS;
        //Selecting Default Radio item here
        this.radioSelected = "item_3";

      // Get row item from array  
        this.radioSel = ITEMS.find(Item => Item.value === this.radioSelected);
        this.radioSelectedString = JSON.stringify(this.radioSel);
      // Radio Change Event


Sample Data for Listing

        export const ITEMS: Item[] = [
                name:'Item 1',
                name:'Item 2',
                name:'Item 3',
                name:'Item 4',
                    name:'Item 5',

link button property to open in new tab?

It throws error.

Microsoft JScript runtime error: 'aspnetForm' is undefined

Foreach loop in java for a custom object list

You can fix your example with the iterator pattern by changing the parametrization of the class:

List<Room> rooms = new ArrayList<Room>();
for(Iterator<Room> i = rooms.iterator(); i.hasNext(); ) {
  String item =;

or much simpler way:

List<Room> rooms = new ArrayList<Room>();
for(Room room : rooms) {

Make an html number input always display 2 decimal places

Look into toFixed for Javascript numbers. You could write an onChange function for your number field that calls toFixed on the input and sets the new value.

Remove sensitive files and their commits from Git history

Use filter-branch:

git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch *file_path_relative_to_git_repo*' --prune-empty --tag-name-filter cat -- --all

git push origin *branch_name* -f

How to get the Mongo database specified in connection string in C#


MongoServer.Create is obsolete now (thanks to @aknuds1). Instead this use following code:

var _server = new MongoClient(connectionString).GetServer();

It's easy. You should first take database name from connection string and then get database by name. Complete example:

var connectionString = "mongodb://localhost:27020/mydb";

//take database name from connection string
var _databaseName = MongoUrl.Create(connectionString).DatabaseName;
var _server = MongoServer.Create(connectionString);

//and then get database by database name:

Important: If your database and auth database are different, you can add a authSource= query parameter to specify a different auth database. (thank you to @chrisdrobison)

From docs:

NOTE If you are using the database segment as the initial database to use, but the username and password specified are defined in a different database, you can use the authSource option to specify the database in which the credential is defined. For example, mongodb://user:pass@hostname/db1?authSource=userDb would authenticate the credential against the userDb database instead of db1.

Post parameter is always null

The issue is that your action method is expecting a simple type i.e., a string parameter value. What you are providing is an object.

There are 2 solutions to your problem.

  1. Create a simple class with "value" property and then use that class as parameter, in which case Web API model binding will read JSON object from request and bind it to your param object "values" property.

  2. Just pass string value "test", and it will work.

How to create a thread?

Your example fails because Thread methods take either one or zero arguments. To create a thread without passing arguments, your code looks like this:

void Start()
    // do stuff

void Test()
    new Thread(new ThreadStart(Start)).Start();

If you want to pass data to the thread, you need to encapsulate your data into a single object, whether that is a custom class of your own design, or a dictionary object or something else. You then need to use the ParameterizedThreadStart delegate, like so:

void Start(object data)
    MyClass myData = (MyClass)myData;
    // do stuff

void Test(MyClass data)
    new Thread(new ParameterizedThreadStart(Start)).Start(data);

Converting between java.time.LocalDateTime and java.util.Date

The fastest way for LocalDateTime -> Date is:


Is it fine to have foreign key as primary key?

Foreign keys are almost always "Allow Duplicates," which would make them unsuitable as Primary Keys.

Instead, find a field that uniquely identifies each record in the table, or add a new field (either an auto-incrementing integer or a GUID) to act as the primary key.

The only exception to this are tables with a one-to-one relationship, where the foreign key and primary key of the linked table are one and the same.

Sort table rows In Bootstrap

These examples are minified because StackOverflow has a maximum character limit and links to external code are discouraged since links can break.

There are multiple plugins if you look: Bootstrap Sortable, Bootstrap Table or DataTables.

Bootstrap 3 with DataTables Example: Bootstrap Docs & DataTables Docs

$(document).ready(function() {
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><h1>Bootstrap 3 DataTables</h1><table cellspacing=0 class="table table-bordered table-hover table-striped"id=example width=100%><thead><tr><th>Name<th>Position<th>Office<th>Salary<tbody><tr><td>Tiger Nixon<td>System Architect<td>Edinburgh<td>$320,800<tr><td>Garrett Winters<td>Accountant<td>Tokyo<td>$170,750<tr><td>Ashton Cox<td>Junior Technical Author<td>San Francisco<td>$86,000<tr><td>Cedric Kelly<td>Senior Javascript Developer<td>Edinburgh<td>$433,060<tr><td>Airi Satou<td>Accountant<td>Tokyo<td>$162,700<tr><td>Brielle Williamson<td>Integration Specialist<td>New York<td>$372,000<tr><td>Herrod Chandler<td>Sales Assistant<td>San Francisco<td>$137,500<tr><td>Rhona Davidson<td>Integration Specialist<td>Tokyo<td>$327,900<tr><td>Colleen Hurst<td>Javascript Developer<td>San Francisco<td>$205,500<tr><td>Sonya Frost<td>Software Engineer<td>Edinburgh<td>$103,600<tr><td>Jena Gaines<td>Office Manager<td>London<td>$90,560<tr><td>Quinn Flynn<td>Support Lead<td>Edinburgh<td>$342,000<tr><td>Charde Marshall<td>Regional Director<td>San Francisco<td>$470,600<tr><td>Haley Kennedy<td>Senior Marketing Designer<td>London<td>$313,500<tr><td>Tatyana Fitzpatrick<td>Regional Director<td>London<td>$385,750<tr><td>Michael Silva<td>Marketing Designer<td>London<td>$198,500<tr><td>Paul Byrd<td>Chief Financial Officer (CFO)<td>New York<td>$725,000<tr><td>Gloria Little<td>Systems Administrator<td>New York<td>$237,500<tr><td>Bradley Greer<td>Software Engineer<td>London<td>$132,000<tr><td>Dai Rios<td>Personnel Lead<td>Edinburgh<td>$217,500<tr><td>Jenette Caldwell<td>Development Lead<td>New York<td>$345,000<tr><td>Yuri Berry<td>Chief Marketing Officer (CMO)<td>New York<td>$675,000<tr><td>Caesar Vance<td>Pre-Sales Support<td>New York<td>$106,450<tr><td>Doris Wilder<td>Sales Assistant<td>Sidney<td>$85,600<tr><td>Angelica Ramos<td>Chief Executive Officer (CEO)<td>London<td>$1,200,000<tr><td>Gavin Joyce<td>Developer<td>Edinburgh<td>$92,575<tr><td>Jennifer Chang<td>Regional Director<td>Singapore<td>$357,650<tr><td>Brenden Wagner<td>Software Engineer<td>San Francisco<td>$206,850<tr><td>Fiona Green<td>Chief Operating Officer (COO)<td>San Francisco<td>$850,000<tr><td>Shou Itou<td>Regional Marketing<td>Tokyo<td>$163,000<tr><td>Michelle House<td>Integration Specialist<td>Sidney<td>$95,400<tr><td>Suki Burks<td>Developer<td>London<td>$114,500<tr><td>Prescott Bartlett<td>Technical Author<td>London<td>$145,000<tr><td>Gavin Cortez<td>Team Leader<td>San Francisco<td>$235,500<tr><td>Martena Mccray<td>Post-Sales support<td>Edinburgh<td>$324,050<tr><td>Unity Butler<td>Marketing Designer<td>San Francisco<td>$85,675<tr><td>Howard Hatfield<td>Office Manager<td>San Francisco<td>$164,500<tr><td>Hope Fuentes<td>Secretary<td>San Francisco<td>$109,850<tr><td>Vivian Harrell<td>Financial Controller<td>San Francisco<td>$452,500<tr><td>Timothy Mooney<td>Office Manager<td>London<td>$136,200<tr><td>Jackson Bradshaw<td>Director<td>New York<td>$645,750<tr><td>Olivia Liang<td>Support Engineer<td>Singapore<td>$234,500<tr><td>Bruno Nash<td>Software Engineer<td>London<td>$163,500<tr><td>Sakura Yamamoto<td>Support Engineer<td>Tokyo<td>$139,575<tr><td>Thor Walton<td>Developer<td>New York<td>$98,540<tr><td>Finn Camacho<td>Support Engineer<td>San Francisco<td>$87,500<tr><td>Serge Baldwin<td>Data Coordinator<td>Singapore<td>$138,575<tr><td>Zenaida Frank<td>Software Engineer<td>New York<td>$125,250<tr><td>Zorita Serrano<td>Software Engineer<td>San Francisco<td>$115,000<tr><td>Jennifer Acosta<td>Junior Javascript Developer<td>Edinburgh<td>$75,650<tr><td>Cara Stevens<td>Sales Assistant<td>New York<td>$145,600<tr><td>Hermione Butler<td>Regional Director<td>London<td>$356,250<tr><td>Lael Greer<td>Systems Administrator<td>London<td>$103,500<tr><td>Jonas Alexander<td>Developer<td>San Francisco<td>$86,500<tr><td>Shad Decker<td>Regional Director<td>Edinburgh<td>$183,000<tr><td>Michael Bruce<td>Javascript Developer<td>Singapore<td>$183,000<tr><td>Donna Snider<td>Customer Support<td>New York<td>$112,000</table></div><script src=></script><script src=></script><script src=></script>

Bootstrap 4 with DataTables Example: Bootstrap Docs & DataTables Docs

$(document).ready(function() {
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><h1>Bootstrap 4 DataTables</h1><table cellspacing=0 class="table table-bordered table-hover table-inverse table-striped"id=example width=100%><thead><tr><th>Name<th>Position<th>Office<th>Age<th>Start date<th>Salary<tfoot><tr><th>Name<th>Position<th>Office<th>Age<th>Start date<th>Salary<tbody><tr><td>Tiger Nixon<td>System Architect<td>Edinburgh<td>61<td>2011/04/25<td>$320,800<tr><td>Garrett Winters<td>Accountant<td>Tokyo<td>63<td>2011/07/25<td>$170,750<tr><td>Ashton Cox<td>Junior Technical Author<td>San Francisco<td>66<td>2009/01/12<td>$86,000<tr><td>Cedric Kelly<td>Senior Javascript Developer<td>Edinburgh<td>22<td>2012/03/29<td>$433,060<tr><td>Airi Satou<td>Accountant<td>Tokyo<td>33<td>2008/11/28<td>$162,700<tr><td>Brielle Williamson<td>Integration Specialist<td>New York<td>61<td>2012/12/02<td>$372,000<tr><td>Herrod Chandler<td>Sales Assistant<td>San Francisco<td>59<td>2012/08/06<td>$137,500<tr><td>Rhona Davidson<td>Integration Specialist<td>Tokyo<td>55<td>2010/10/14<td>$327,900<tr><td>Colleen Hurst<td>Javascript Developer<td>San Francisco<td>39<td>2009/09/15<td>$205,500<tr><td>Sonya Frost<td>Software Engineer<td>Edinburgh<td>23<td>2008/12/13<td>$103,600<tr><td>Jena Gaines<td>Office Manager<td>London<td>30<td>2008/12/19<td>$90,560<tr><td>Quinn Flynn<td>Support Lead<td>Edinburgh<td>22<td>2013/03/03<td>$342,000<tr><td>Charde Marshall<td>Regional Director<td>San Francisco<td>36<td>2008/10/16<td>$470,600<tr><td>Haley Kennedy<td>Senior Marketing Designer<td>London<td>43<td>2012/12/18<td>$313,500<tr><td>Tatyana Fitzpatrick<td>Regional Director<td>London<td>19<td>2010/03/17<td>$385,750<tr><td>Michael Silva<td>Marketing Designer<td>London<td>66<td>2012/11/27<td>$198,500<tr><td>Paul Byrd<td>Chief Financial Officer (CFO)<td>New York<td>64<td>2010/06/09<td>$725,000<tr><td>Gloria Little<td>Systems Administrator<td>New York<td>59<td>2009/04/10<td>$237,500<tr><td>Bradley Greer<td>Software Engineer<td>London<td>41<td>2012/10/13<td>$132,000<tr><td>Dai Rios<td>Personnel Lead<td>Edinburgh<td>35<td>2012/09/26<td>$217,500<tr><td>Jenette Caldwell<td>Development Lead<td>New York<td>30<td>2011/09/03<td>$345,000<tr><td>Yuri Berry<td>Chief Marketing Officer (CMO)<td>New York<td>40<td>2009/06/25<td>$675,000<tr><td>Caesar Vance<td>Pre-Sales Support<td>New York<td>21<td>2011/12/12<td>$106,450<tr><td>Doris Wilder<td>Sales Assistant<td>Sidney<td>23<td>2010/09/20<td>$85,600<tr><td>Angelica Ramos<td>Chief Executive Officer (CEO)<td>London<td>47<td>2009/10/09<td>$1,200,000<tr><td>Gavin Joyce<td>Developer<td>Edinburgh<td>42<td>2010/12/22<td>$92,575<tr><td>Jennifer Chang<td>Regional Director<td>Singapore<td>28<td>2010/11/14<td>$357,650<tr><td>Brenden Wagner<td>Software Engineer<td>San Francisco<td>28<td>2011/06/07<td>$206,850<tr><td>Fiona Green<td>Chief Operating Officer (COO)<td>San Francisco<td>48<td>2010/03/11<td>$850,000<tr><td>Shou Itou<td>Regional Marketing<td>Tokyo<td>20<td>2011/08/14<td>$163,000<tr><td>Michelle House<td>Integration Specialist<td>Sidney<td>37<td>2011/06/02<td>$95,400<tr><td>Suki Burks<td>Developer<td>London<td>53<td>2009/10/22<td>$114,500<tr><td>Prescott Bartlett<td>Technical Author<td>London<td>27<td>2011/05/07<td>$145,000<tr><td>Gavin Cortez<td>Team Leader<td>San Francisco<td>22<td>2008/10/26<td>$235,500<tr><td>Martena Mccray<td>Post-Sales support<td>Edinburgh<td>46<td>2011/03/09<td>$324,050<tr><td>Unity Butler<td>Marketing Designer<td>San Francisco<td>47<td>2009/12/09<td>$85,675<tr><td>Howard Hatfield<td>Office Manager<td>San Francisco<td>51<td>2008/12/16<td>$164,500<tr><td>Hope Fuentes<td>Secretary<td>San Francisco<td>41<td>2010/02/12<td>$109,850<tr><td>Vivian Harrell<td>Financial Controller<td>San Francisco<td>62<td>2009/02/14<td>$452,500<tr><td>Timothy Mooney<td>Office Manager<td>London<td>37<td>2008/12/11<td>$136,200<tr><td>Jackson Bradshaw<td>Director<td>New York<td>65<td>2008/09/26<td>$645,750<tr><td>Olivia Liang<td>Support Engineer<td>Singapore<td>64<td>2011/02/03<td>$234,500<tr><td>Bruno Nash<td>Software Engineer<td>London<td>38<td>2011/05/03<td>$163,500<tr><td>Sakura Yamamoto<td>Support Engineer<td>Tokyo<td>37<td>2009/08/19<td>$139,575<tr><td>Thor Walton<td>Developer<td>New York<td>61<td>2013/08/11<td>$98,540<tr><td>Finn Camacho<td>Support Engineer<td>San Francisco<td>47<td>2009/07/07<td>$87,500<tr><td>Serge Baldwin<td>Data Coordinator<td>Singapore<td>64<td>2012/04/09<td>$138,575<tr><td>Zenaida Frank<td>Software Engineer<td>New York<td>63<td>2010/01/04<td>$125,250<tr><td>Zorita Serrano<td>Software Engineer<td>San Francisco<td>56<td>2012/06/01<td>$115,000<tr><td>Jennifer Acosta<td>Junior Javascript Developer<td>Edinburgh<td>43<td>2013/02/01<td>$75,650<tr><td>Cara Stevens<td>Sales Assistant<td>New York<td>46<td>2011/12/06<td>$145,600<tr><td>Hermione Butler<td>Regional Director<td>London<td>47<td>2011/03/21<td>$356,250<tr><td>Lael Greer<td>Systems Administrator<td>London<td>21<td>2009/02/27<td>$103,500<tr><td>Jonas Alexander<td>Developer<td>San Francisco<td>30<td>2010/07/14<td>$86,500<tr><td>Shad Decker<td>Regional Director<td>Edinburgh<td>51<td>2008/11/13<td>$183,000<tr><td>Michael Bruce<td>Javascript Developer<td>Singapore<td>29<td>2011/06/27<td>$183,000<tr><td>Donna Snider<td>Customer Support<td>New York<td>27<td>2011/01/25<td>$112,000</table></div><script src=></script><script src=></script><script src=></script>

Bootstrap 3 with Bootstrap Table Example: Bootstrap Docs & Bootstrap Table Docs

<link href= rel=stylesheet><link href= rel=stylesheet><table data-sort-name=stargazers_count data-sort-order=desc data-toggle=table data-url=""><thead><tr><th data-field=name data-sortable=true>Name<th data-field=stargazers_count data-sortable=true>Stars<th data-field=forks_count data-sortable=true>Forks<th data-field=description data-sortable=true>Description</thead></table><script src=></script><script src=></script>

Bootstrap 3 with Bootstrap Sortable Example: Bootstrap Docs & Bootstrap Sortable Docs

function randomDate(t,e){return new Date(t.getTime()+Math.random()*(e.getTime()-t.getTime()))}function randomName(){return["Jack","Peter","Frank","Steven"][Math.floor(4*Math.random())]+" "+["White","Jackson","Sinatra","Spielberg"][Math.floor(4*Math.random())]}function newTableRow(){var t=moment(randomDate(new Date(2e3,0,1),new Date)).format("D.M.YYYY"),e=Math.round(Math.random()*Math.random()*100*100)/100,a=Math.round(Math.random()*Math.random()*100*100)/100,r=Math.round(Math.random()*Math.random()*100*100)/100;return"<tr><td>"+randomName()+"</td><td>"+e+"</td><td>"+a+"</td><td>"+r+"</td><td>"+Math.round(100*(e+a+r))/100+"</td><td data-dateformat='D-M-YYYY'>"+t+"</td></tr>"}function customSort(){alert("Custom sort.")}!function(t,e){"use strict";"function"==typeof define&&define.amd?define("tinysort",function(){return e}):t.tinysort=e}(this,function(){"use strict";function t(t,e){for(var a,r=t.length,o=r;o--;)e(t[a=r-o-1],a)}function e(t,e,a){for(var o in e)(a||t[o]===r)&&(t[o]=e[o]);return t}function a(t,e,a){u.push({prepare:t,sort:e,sortBy:a})}var r,o=!1,n=null,s=window,d=s.document,i=parseFloat,l=/(-?\d+\.?\d*)\s*$/g,c=/(\d+\.?\d*)\s*$/g,u=[],f=0,h=0,p=String.fromCharCode(4095),m={selector:n,order:"asc",attr:n,data:n,useVal:o,place:"org",returns:o,cases:o,natural:o,forceStrings:o,ignoreDashes:o,sortFunction:n,useFlex:o,emptyEnd:o};return s.Element&&function(t){t.matchesSelector=t.matchesSelector||t.mozMatchesSelector||t.msMatchesSelector||t.oMatchesSelector||t.webkitMatchesSelector||function(t){for(var e=this,a=(e.parentNode||e.document).querySelectorAll(t),r=-1;a[++r]&&a[r]!=e;);return!!a[r]}}(Element.prototype),e(a,{loop:t}),e(function(a,s){function v(t){var a=!!t.selector,r=a&&":"===t.selector[0],o=e(t||{},m);E.push(e({hasSelector:a,hasAttr:!(o.attr===n||""===o.attr),!==n,hasFilter:r,sortReturnNumber:"asc"===o.order?1:-1},o))}function b(t,e,a){for(var r=a(t.toString()),o=a(e.toString()),n=0;r[n]&&o[n];n++)if(r[n]!==o[n]){var s=Number(r[n]),d=Number(o[n]);return s==r[n]&&d==o[n]?s-d:r[n]>o[n]?1:-1}return r.length-o.length}function g(t){for(var e,a,r=[],o=0,n=-1,s=0;e=(a=t.charAt(o++)).charCodeAt(0);){var d=46==e||e>=48&&57>=e;d!==s&&(r[++n]="",s=d),r[n]+=a}return r}function w(){return Y.forEach(function(t){F.appendChild(t.elm)}),F}function S(t){var e=t.elm,a=d.createElement("div");return t.ghost=a,e.parentNode.insertBefore(a,e),t}function y(t,e){var a=t.ghost,r=a.parentNode;r.insertBefore(e,a),r.removeChild(a),delete t.ghost}function C(t,e){var a,r=t.elm;return e.selector&&(e.hasFilter?r.matchesSelector(e.selector)||(r=n):r=r.querySelector(e.selector)),e.hasAttr?a=r.getAttribute(e.attr):e.useVal?a=r.value||r.getAttribute("value"):e.hasData?a=r.getAttribute("data-",M(a)&&(e.cases||(a=a.toLowerCase()),a=a.replace(/\s+/g," ")),null===a&&(a=p),a}function M(t){return"string"==typeof t}M(a)&&(a=d.querySelectorAll(a)),0===a.length&&console.warn("No elements to sort");var x,N,F=d.createDocumentFragment(),D=[],Y=[],$=[],E=[],k=!0,A=a.length&&a[0].parentNode,T=A.rootNode!==document,R=a.length&&(s===r||!1!==s.useFlex)&&!T&&-1!==getComputedStyle(A,null).display.indexOf("flex");return function(){0===arguments.length?v({}):t(arguments,function(t){v(M(t)?{selector:t}:t)}),f=E.length}.apply(n,,1)),t(a,function(t,e){N?N!==t.parentNode&&(k=!1):N=t.parentNode;var a=E[0],r=a.hasFilter,o=a.selector,n=!o||r&&t.matchesSelector(o)||o&&t.querySelector(o)?Y:$,s={elm:t,pos:e,posn:n.length};D.push(s),n.push(s)}),x=Y.slice(0),Y.sort(function(e,a){var n=0;for(0!==h&&(h=0);0===n&&f>h;){var s=E[h],d=s.ignoreDashes?c:l;if(t(u,function(t){var e=t.prepare;e&&e(s)}),s.sortFunction)n=s.sortFunction(e,a);else if("rand"==s.order)n=Math.random()<.5?1:-1;else{var p=o,m=C(e,s),v=C(a,s),w=""===m||m===r,S=""===v||v===r;if(m===v)n=0;else if(s.emptyEnd&&(w||S))n=w&&S?0:w?1:-1;else{if(!s.forceStrings){var 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define&&define.amd?define(["jquery","tinysort","moment"],e):e(t.jQuery,t.tinysort,t.moment||void 0)}(this,function(t,e,a){var r,o,n,s=t(document);function d(e){var s=void 0!==a;r=e.sign?e.sign:"arrow","default"==e.customSort&&(e.customSort=c),o=e.customSort||o||c,n=e.emptyEnd,t("table.sortable").each(function(){var r=t(this),o=!0===e.applyLast;r.find("span.sign").remove(),r.find("> thead [colspan]").each(function(){for(var e=parseFloat(t(this).attr("colspan")),a=1;a<e;a++)t(this).after('<th class="colspan-compensate">')}),r.find("> thead [rowspan]").each(function(){for(var e=t(this),a=parseFloat(e.attr("rowspan")),r=1;r<a;r++){var o=e.parent("tr"),"tr"),s=o.children().index(e);n.children().eq(s).before('<th class="rowspan-compensate">')}}),r.find("> thead tr").each(function(e){t(this).find("th").each(function(a){var r=t(this);r.addClass("nosort").removeClass("up down"),r.attr("data-sortcolumn",a),r.attr("data-sortkey",a+"-"+e)})}),r.find("> thead .rowspan-compensate, .colspan-compensate").remove(),r.find("th").each(function(){var e=t(this);if(void 0!==e.attr("data-dateformat")&&s){var o=parseFloat(e.attr("data-sortcolumn"));r.find("td:nth-child("+(o+1)+")").each(function(){var r=t(this);r.attr("data-value",a(r.text(),e.attr("data-dateformat")).format("YYYY/MM/DD/HH/mm/ss"))})}else if(void 0!==e.attr("data-valueprovider")){o=parseFloat(e.attr("data-sortcolumn"));r.find("td:nth-child("+(o+1)+")").each(function(){var a=t(this);a.attr("data-value",new RegExp(e.attr("data-valueprovider")).exec(a.text())[0])})}}),r.find("td").each(function(){var e=t(this);void 0!==e.attr("data-dateformat")&&s?e.attr("data-value",a(e.text(),e.attr("data-dateformat")).format("YYYY/MM/DD/HH/mm/ss")):void 0!==e.attr("data-valueprovider")?e.attr("data-value",new RegExp(e.attr("data-valueprovider")).exec(e.text())[0]):void 0===e.attr("data-value")&&e.attr("data-value",e.text())});var n=l(r),d=n.bsSort;r.find('> thead th[data-defaultsort!="disabled"]').each(function(e){var a=t(this),r=a.closest("table.sortable");"sortTable",r);var s=a.attr("data-sortkey"),i=o?n.lastSort:-1;d[s]=o?d[s]:a.attr("data-defaultsort"),void 0!==d[s]&&o===(s===i)&&(d[s]="asc"===d[s]?"desc":"asc",u(a,r))})})}function i(e){var a=t(e),"sortTable")||a.closest("table.sortable");u(a,r)}function l(e){var"bootstrap-sortable-context");return void 0===a&&(a={bsSort:[],lastSort:void 0},e.find('> thead th[data-defaultsort!="disabled"]').each(function(e){var r=t(this),o=r.attr("data-sortkey");a.bsSort[o]=r.attr("data-defaultsort"),void 0!==a.bsSort[o]&&(a.lastSort=o)}),"bootstrap-sortable-context",a)),a}function c(t,a){e(t,a)}function u(e,a){a.trigger("before-sort");var s=parseFloat(e.attr("data-sortcolumn")),d=l(a),i=d.bsSort;if(e.attr("colspan")){var c=parseFloat("mainsort"))||0,f=parseFloat("sortkey").split("-").pop());if(a.find("> thead tr").length-1>f)return void u(a.find('[data-sortkey="'+(s+c)+"-"+(f+1)+'"]'),a);s+=c}var h=e.attr("data-defaultsign")||r;if(a.find("> thead th").each(function(){t(this).removeClass("up").removeClass("down").addClass("nosort")}),t.browser.mozilla){var p=a.find("> thead div.mozilla");void 0!==p&&(p.find(".sign").remove(),p.parent().html(p.html())),e.wrapInner('<div class="mozilla"></div>'),e.children().eq(0).append('<span class="sign '+h+'"></span>')}else a.find("> thead span.sign").remove(),e.append('<span class="sign '+h+'"></span>');var m=e.attr("data-sortkey"),v="desc"!==e.attr("data-firstsort")?"desc":"asc",b=i[m]||v;d.lastSort!==m&&void 0!==i[m]||(b="asc"===b?"desc":"asc"),i[m]=b,d.lastSort=m,"desc"===i[m]?(e.find("span.sign").addClass("up"),e.addClass("up").removeClass("down nosort")):e.addClass("down").removeClass("up nosort");var g=a.children("tbody").children("tr"),w=[];t(g.filter('[data-disablesort="true"]').get().reverse()).each(function(e,a){var r=t(a);w.push({index:g.index(r),row:r}),r.remove()});var S=g.not('[data-disablesort="true"]');if(0!=S.length){var y="asc"===i[m]&&n;o(S,{emptyEnd:y,selector:"td:nth-child("+(s+1)+")",order:i[m],data:"value"})}t(w.reverse()).each(function(t,e){0===e.index?a.children("tbody").prepend(e.row):a.children("tbody").children("tr").eq(e.index-1).after(e.row)}),a.find("> tbody > tr > td.sorted,> thead th.sorted").removeClass("sorted"),S.find("td:eq("+s+")").addClass("sorted"),e.addClass("sorted"),a.trigger("sorted")}if(t.bootstrapSortable=function(t){null==t?d({}):t.constructor===Boolean?d({applyLast:t}):void 0!==t.sortingHeader?i(t.sortingHeader):d(t)},s.on("click",'table.sortable>thead th[data-defaultsort!="disabled"]',function(t){i(this)}),!t.browser){t.browser={chrome:!1,mozilla:!1,opera:!1,msie:!1,safari:!1};var f=navigator.userAgent;t.each(t.browser,function(e){t.browser[e]=!!new RegExp(e,"i").test(f),t.browser.mozilla&&"mozilla"===e&&(t.browser.mozilla=!!new RegExp("firefox","i").test(f)),"safari"===e&&(t.browser.safari=!1)})}t(t.bootstrapSortable)}),function(){var t=$("table");t.append(newTableRow()),t.append(newTableRow()),$("button.add-row").on("click",function(){var e=$(this);t.append(newTableRow()),"sort")?$.bootstrapSortable(!0):$.bootstrapSortable(!1)}),$("button.change-sort").on("click",function(){$(this).data("custom")?$.bootstrapSortable(!0,void 0,customSort):$.bootstrapSortable(!0,void 0,"default")}),t.on("sorted",function(){alert("Table was sorted.")}),$("#event").on("change",function(){$(this).is(":checked")?t.on("sorted",function(){alert("Table was sorted.")})"sorted")}),$("input[name=sign]:radio").change(function(){$.bootstrapSortable(!0,$(this).val())})}();
table.sortable span.sign { display: block; position: absolute; top: 50%; right: 5px; font-size: 12px; margin-top: -10px; color: #bfbfc1; } table.sortable th:after { display: block; position: absolute; top: 50%; right: 5px; font-size: 12px; margin-top: -10px; color: #bfbfc1; } table.sortable th.arrow:after { content: ''; } table.sortable span.arrow, span.reversed, th.arrow.down:after, th.reversedarrow.down:after, th.arrow.up:after, th.reversedarrow.up:after { border-style: solid; border-width: 5px; font-size: 0; border-color: #ccc transparent transparent transparent; line-height: 0; height: 0; width: 0; margin-top: -2px; } table.sortable span.arrow.up, th.arrow.up:after { border-color: transparent transparent #ccc transparent; margin-top: -7px; } table.sortable span.reversed, th.reversedarrow.down:after { border-color: transparent transparent #ccc transparent; margin-top: -7px; } table.sortable span.reversed.up, th.reversedarrow.up:after { border-color: #ccc transparent transparent transparent; margin-top: -2px; } table.sortable, { content: "a .. z"; } table.sortable, { content: "z .. a"; } table.sortable, th.AZ.nosort:after, th._19.nosort:after, th.month.nosort:after { content: ".."; } table.sortable span.AZ:before, th.AZ.down:after { content: "A .. Z"; } table.sortable span.AZ.up:before, th.AZ.up:after { content: "Z .. A"; } table.sortable span._19:before, th._19.down:after { content: "1 .. 9"; } table.sortable span._19.up:before, th._19.up:after { content: "9 .. 1"; } table.sortable span.month:before, th.month.down:after { content: "jan .. dec"; } table.sortable span.month.up:before, th.month.up:after { content: "dec .. jan"; } table.sortable thead th:not([data-defaultsort=disabled]) { cursor: pointer; position: relative; top: 0; left: 0; } table.sortable thead th:hover:not([data-defaultsort=disabled]) { background: #efefef; } table.sortable thead th div.mozilla { position: relative; }
<link href= rel=stylesheet><link href= rel=stylesheet><div class=container><div class=hero-unit><h1>Bootstrap Sortable</h1></div><table class="sortable table table-bordered table-striped"><thead><tr><th style=width:20%;vertical-align:middle data-defaultsign=nospan class=az data-defaultsort=asc rowspan=2><i class="fa fa-fw fa-map-marker"></i>Name<th style=text-align:center colspan=4 data-mainsort=3>Results<th data-defaultsort=disabled><tr><th style=width:20% colspan=2 data-mainsort=1 data-firstsort=desc>Round 1<th style=width:20%>Round 2<th style=width:20%>Total<t

Disable time in bootstrap date time picker

I tried all of the solutions posted here but none of them worked for me. I managed to disable the time by using this line of code in my jQuery:

    format: 'YYYY-MM-DD'

This set the format to date only and disabled the time completely. Hope this helps.

Django Multiple Choice Field / Checkbox Select Multiple

Brant's solution is absolutely correct, but I needed to modify it to make it work with multiple select checkboxes and commit=false. Here is my solution:

class Choices(models.Model):
    description = models.CharField(max_length=300)

class Profile(models.Model):
   user = models.ForeignKey(User, blank=True, unique=True, verbose_name_('user'))
   the_choices = models.ManyToManyField(Choices)

class ProfileForm(forms.ModelForm):
    the_choices = forms.ModelMultipleChoiceField(queryset=Choices.objects.all(), required=False, widget=forms.CheckboxSelectMultiple)

    class Meta:
        model = Profile
        exclude = ['user']

if request.method=='POST':
    form = ProfileForm(request.POST)
    if form.is_valid():
        profile =
        profile.user = request.user
        form.save_m2m() # needed since using commit=False
        form = ProfileForm()

return render_to_response(template_name, {"profile_form": form}, context_instance=RequestContext(request))

How can you search Google Programmatically Java API

Indeed there is an API to search google programmatically. The API is called google custom search. For using this API, you will need an Google Developer API key and a cx key. A simple procedure for accessing google search from java program is explained in my blog.

Now dead, here is the Wayback Machine link.

Perl: function to trim string leading and trailing whitespace

This is available in String::Util with the trim method:

Editor's note: String::Util is not a core module, but you can install it from CPAN with [sudo] cpan String::Util.

use String::Util 'trim';
my $str = "  hello  ";
$str = trim($str);
print "string is now: '$str'\n";


string is now 'hello'

However it is easy enough to do yourself:

$str =~ s/^\s+//;
$str =~ s/\s+$//;

Python Requests package: Handling xml response

requests does not handle parsing XML responses, no. XML responses are much more complex in nature than JSON responses, how you'd serialize XML data into Python structures is not nearly as straightforward.

Python comes with built-in XML parsers. I recommend you use the ElementTree API:

import requests
from xml.etree import ElementTree

response = requests.get(url)

tree = ElementTree.fromstring(response.content)

or, if the response is particularly large, use an incremental approach:

    response = requests.get(url, stream=True)
    # if the server sent a Gzip or Deflate compressed response, decompress
    # as we read the raw stream:
    response.raw.decode_content = True

    events = ElementTree.iterparse(response.raw)
    for event, elem in events:
        # do something with `elem`

The external lxml project builds on the same API to give you more features and power still.

Converting UTF-8 to ISO-8859-1 in Java - how to keep it as single byte

Starting with a set of bytes which encode a string using UTF-8, creates a string from that data, then get some bytes encoding the string in a different encoding:

    byte[] utf8bytes = { (byte)0xc3, (byte)0xa2, 0x61, 0x62, 0x63, 0x64 };
    Charset utf8charset = Charset.forName("UTF-8");
    Charset iso88591charset = Charset.forName("ISO-8859-1");

    String string = new String ( utf8bytes, utf8charset );


    // "When I do a getbytes(encoding) and "
    byte[] iso88591bytes = string.getBytes(iso88591charset);

    for ( byte b : iso88591bytes )
        System.out.printf("%02x ", b);


    // "then create a new string with the bytes in ISO-8859-1 encoding"
    String string2 = new String ( iso88591bytes, iso88591charset );

    // "I get a two different chars"

this outputs strings and the iso88591 bytes correctly:

e2 61 62 63 64 

So your byte array wasn't paired with the correct encoding:

    String failString = new String ( utf8bytes, iso88591charset );




(either that, or you just wrote the utf8 bytes to a file and read them elsewhere as iso88591)

When to use React "componentDidUpdate" method?

A simple example would be an app that collects input data from the user and then uses Ajax to upload said data to a database. Here's a simplified example (haven't run it - may have syntax errors):

export default class Task extends React.Component {
  constructor(props, context) {
    super(props, context);
    this.state = {
      name: "",
      age: "",
      country: ""

  componentDidUpdate() {

  _changeName = (e) => {

  _changeAge = (e) => {

  _changeCountry = (e) => {

  _commitAutoSave = () => {
    Ajax.postJSON('/someAPI/json/autosave', {
      age: this.state.age,

  render() {
    let {name, age, country} = this.state;
    return (
        <input type="text" value={name} onChange={this._changeName} />
        <input type="text" value={age} onChange={this._changeAge} />
        <input type="text" value={country} onChange={this._changeCountry} />

So whenever the component has a state change it will autosave the data. There are other ways to implement it too. The componentDidUpdate is particularly useful when an operation needs to happen after the DOM is updated and the update queue is emptied. It's probably most useful on complex renders and state or DOM changes or when you need something to be the absolutely last thing to be executed.

The example above is rather simple though, but probably proves the point. An improvement could be to limit the amount of times the autosave can execute (e.g max every 10 seconds) because right now it will run on every key-stroke.

I made a demo on this fiddle as well to demonstrate.

For more info, refer to the official docs:

componentDidUpdate() is invoked immediately after updating occurs. This method is not called for the initial render.

Use this as an opportunity to operate on the DOM when the component has been updated. This is also a good place to do network requests as long as you compare the current props to previous props (e.g. a network request may not be necessary if the props have not changed).

How to animate the change of image in an UIImageView?

Swift 4 This is just awesome

  self.imgViewPreview.transform = CGAffineTransform(scaleX: 0, y: 0)
          UIView.animate(withDuration: 1, delay: 0, usingSpringWithDamping: 0.3, initialSpringVelocity: 0, options: .curveEaseOut, animations: {
              self.imgViewPreview.image = newImage
              self.imgViewPreview.transform = .identity
          }, completion: nil)

POST request send json data java HttpUrlConnection

the correct answer is good , but

OutputStreamWriter wr= new OutputStreamWriter(con.getOutputStream());

not work for me , instead of it , use :

byte[] outputBytes = rootJsonObject.getBytes("UTF-8");
OutputStream os = con.getOutputStream();

PyCharm import external library

Update (2018-01-06): This answer is obsolete. Modern versions of PyCharm provide Paths via Settings ? Project Interpreter ? ? ? Show All ? Show paths button.

PyCharm Professional Edition has the Paths tab in Python Interpreters settings, but Community Edition apparently doesn't have it.

As a workaround, you can create a symlink for your imported library under your project's root.

For example:

    third_party -> /some/other/directory/third_party

How to write data to a JSON file using Javascript

JSON can be written into local storage using the JSON.stringify to serialize a JS object. You cannot write to a JSON file using only JS. Only cookies or local storage

    var obj = {"nissan": "sentra", "color": "green"};

localStorage.setItem('myStorage', JSON.stringify(obj));

And to retrieve the object later

var obj = JSON.parse(localStorage.getItem('myStorage'));

Syntax for an If statement using a boolean

You can change the value of a bool all you want. As for an if:

if randombool == True:

works, but you can also use:

if randombool:

If you want to test whether something is false you can use:

if randombool == False

but you can also use:

if not randombool:

XPath to return only elements containing the text, and not its parents

Do you want to find elements that contain "match", or that equal "match"?

This will find elements that have text nodes that equal 'match' (matches none of the elements because of leading and trailing whitespace in random2):


This will find all elements that have text nodes that equal "match", after removing leading and trailing whitespace(matches random2):


This will find all elements that contain 'match' in the text node value (matches random2 and random3):


This XPATH 2.0 solution uses the matches() function and a regex pattern that looks for text nodes that contain 'match' and begin at the start of the string(i.e. ^) or a word boundary (i.e. \W) and terminated by the end of the string (i.e. $) or a word boundary. The third parameter i evaluates the regex pattern case-insensitive. (matches random2)


"Comparison method violates its general contract!"

If compareParents(s1, s2) == -1 then compareParents(s2, s1) == 1 is expected. With your code it's not always true.

Specifically if s1.getParent() == s2 && s2.getParent() == s1. It's just one of the possible problems.

Matplotlib transparent line plots

Plain and simple:

plt.plot(x, y, 'r-', alpha=0.7)

(I know I add nothing new, but the straightforward answer should be visible).

Multiple commands on a single line in a Windows batch file


echo %time% & dir & echo %time%

This is, from memory, equivalent to the semi-colon separator in bash and other UNIXy shells.

There's also && (or ||) which only executes the second command if the first succeeded (or failed), but the single ampersand & is what you're looking for here.

That's likely to give you the same time however since environment variables tend to be evaluated on read rather than execute.

You can get round this by turning on delayed expansion:

pax> cmd /v:on /c "echo !time! & ping >nul: & echo !time!"

That's needed from the command line. If you're doing this inside a script, you can just use setlocal:

@setlocal enableextensions enabledelayedexpansion
@echo off
echo !time! & ping >nul: & echo !time!

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

we can directly see the indexes on to the table if we know the index name with below :

select * from all_indexes where index_name= 'your index'

How to send emails from my Android application?

Sending email can be done with Intents which will require no configuration. But then it will require user interaction and the layout will be a bit restricted.

Build and sending a more complex email without user interaction entails building your own client. The first thing is that the Sun Java API for email are unavailable. I have had success leveraging the Apache Mime4j library to build email. All based on the docs at nilvec.

Homebrew install specific version of formula?

Edit: 2021, this answer is no longer functional due to the github install being deprecated. (Thanks Tim Smith for update).

Install an old brew package version (Flyway 4.2.0 example)

Find your local homebrew git dir or clone Homebrew/homebrew-core locally

cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/


git clone [email protected]:Homebrew/homebrew-core.git

List all available versions

git log master -- Formula/flyway.rb

Copy the commit ID for the version you want and install it directly

brew install


You can get desired result with help of Regular Expressions.

SELECT fiberbox from fiberbox where fiberbox REGEXP '[1740|1938|1940]';

We can test the above query please click SQL fiddle

SELECT fiberbox from fiberbox where fiberbox REGEXP '[174019381940]';

We can test the above query please click SQL fiddle

check / uncheck checkbox using jquery?

You can set the state of the checkbox based on the value:

$('#your-checkbox').prop('checked', value == 1);

Spring's overriding bean

Not sure if that's exactly what you need, but we are using profiles to define the environment we are running at and specific bean for each environment, so it's something like that:

<bean name="myBean" class="myClass">
    <constructor-arg name="name" value="originalValue" />
<beans profile="DEV, default">
     <!-- Specific DEV configurations, also default if no profile defined -->
    <bean name="myBean" class="myClass">
        <constructor-arg name="name" value="overrideValue" />
<beans profile="CI, UAT">
     <!-- Specific CI / UAT configurations -->
<beans profile="PROD">
     <!-- Specific PROD configurations -->

So in this case, if I don't define a profile or if I define it as "DEV" myBean will get "overrideValue" for it's name argument. But if I set the profile to "CI", "UAT" or "PROD" it will get "originalValue" as the value.

making matplotlib scatter plots from dataframes in Python's pandas

There is little to be added to Garrett's great answer, but pandas also has a scatter method. Using that, it's as easy as

df = pd.DataFrame(np.random.randn(10,2), columns=['col1','col2'])
df['col3'] = np.arange(len(df))**2 * 100 + 100
df.plot.scatter('col1', 'col2', df['col3'])

plotting sizes in col3 to col1-col2

How to save DataFrame directly to Hive?

I don't see df.write.saveAsTable(...) deprecated in Spark 2.0 documentation. It has worked for us on Amazon EMR. We were perfectly able to read data from S3 into a dataframe, process it, create a table from the result and read it with MicroStrategy. Vinays answer has also worked though.

Difference between java.exe and javaw.exe

The difference is in the subsystem that each executable targets.

  • java.exe targets the CONSOLE subsystem.
  • javaw.exe targets the WINDOWS subsystem.

Comparing strings, c++

string cat = "cat";
string human = "human";

cout << << endl; 

This code will give -1 as a result. This is due to the first non-matching character of the compared string 'h' is lower or appears after 'c' in alphabetical order, even though the compared string, 'human' is longer than 'cat'.

I find the return value described in is more accurate which are-:

0 : They compare equal

<0 : Either the value of the first character that does not match is lower in the compared string, or all compared characters match but the compared string is shorter.

more than 0 : Either the value of the first character that does not match is greater in the compared string, or all compared characters match but the compared string is longer.

Moreover, IMO's description is simpler and so far best describe to my own experience.

negative value if *this appears before the character sequence specified by the arguments, in lexicographical order

zero if both character sequences compare equivalent

positive value if *this appears after the character sequence specified by the arguments, in lexicographical order

copy all files and folders from one drive to another drive using DOS (command prompt)

try this command, xcopy c:\ (file or directory path) F:\ /e. If you want more details refer this site [[]]

How to get the data-id attribute?

I use $.data -

//Set value 7 to data-id 
$.data(this, 'id', 7);

//Get value from data-id
alert( $(this).data("id") ); // => outputs 7

How to change the text of a button in jQuery?

The correct way of changing the button text if it was "buttonized" using JQuery is to use .button() method:

$( ".selector" ).button( "option", "label", "new text" );

How to include !important in jquery

For those times when you need to use jquery to set !important properties, here is a plugin I build that will allow you to do so.

$.fn.important = function(key, value) {
    var q = Object.assign({},
    q[key] = `${value} !important`;
    $(this).css("cssText", Object.entries(q).filter(x => x[1]).map(([k, v]) => (`${k}: ${v}`)).join(';'));

$('div').important('color', 'red');

How can I get the file name from request.FILES?

NOTE if you are using python 3.x:

request.FILES is a multivalue dictionary like object that keeps the files uploaded through an upload file button. Say in your html code the name of the button (type="file") is "myfile" so "myfile" will be the key in this dictionary. If you uploaded one file, then the value for this key will be only one and if you uploaded multiple files, then you will have multiple values for that specific key. If you use request.FILES['myfile'] you will get the first or last value (I cannot say for sure). This is fine if you only uploaded one file, but if you want to get all files you should do this:

list=[] #myfile is the key of a multi value dictionary, values are the uploaded files
for f in request.FILES.getlist('myfile'): #myfile is the name of your html file button
    filename =

of course one can squeeze the whole thing in one line, but this is easy to understand

Change font size of UISegmentedControl

Daniel pointed me to correct way. I used it like this-

float scaleFactor = 0.8f;

UISegmentedControl *segmentedControl = [[UISegmentedControl alloc]
initWithFrame:CGRectMake(10, 70, 300/scaleFactor,35)];

[segmentedControl insertSegmentWithTitle:@"..." atIndex:0 animated:NO];
[segmentedControl insertSegmentWithTitle:@"..." atIndex:1 animated:NO];
[segmentedControl insertSegmentWithTitle:@"..." atIndex:2 animated:NO];

segmentedControl.transform = CGAffineTransformMakeScale(scaleFactor, 1);
CGPoint segmentedControlCenter =;
segmentedControlCenter.x =; = segmentedControlCenter;

S3 limit to objects in a bucket

While you can store an unlimited number of files/objects in a single bucket, when you go to list a "directory" in a bucket, it will only give you the first 1000 files/objects in that bucket by default. To access all the files in a large "directory" like this, you need to make multiple calls to their API.

Initialization of all elements of an array to one default value in C++?

With {} you assign the elements as they are declared; the rest is initialized with 0.

If there is no = {} to initalize, the content is undefined.

YouTube embedded video: set different thumbnail

The answers did not work for me. Maybe they were outdated.

Anyway, found this website, which does all the job for you, and even prevent you from needing to read the unclear-as-usual google documentation:

Copying the cell value preserving the formatting from one cell to another in excel using VBA

To copy formatting:

Range("I10:J10").Select ' note that we select the whole merged cell
Selection.PasteSpecial Paste:=xlPasteFormats

copying the formatting will break the merged cells, so you can use this to put the cell back together


To copy a cell value, without copying anything else (and not using copy/paste), you can address the cells directly

Range("I10").Value = Range("F10").Value

other properties (font, color, etc ) can also be copied by addressing the range object properties directly in the same way

Setting max width for body using Bootstrap

In responsive.less, you can comment out the line that imports responsive-1200px-min.less.

// Large desktops

@import "responsive-1200px-min.less";

Like so:

// Large desktops

// @import "responsive-1200px-min.less";

iPhone SDK on Windows (alternative solutions)

I looked into this before buying a Mac Mini. The answer is, essentially, no. You pretty much have to buy a Leopard Mac to do iPhone SDK development for apps that run on non-jailbroken iPhones.

Not that it's 100% impossible, but it's 99.99% unreasonable. Like changing light bulbs with your feet.

Not only do you have to be in Xcode, but you have to get certificates into the Keychain manager to be able to have Xcode and the iPhone communicate. And you have to set all kinds of setting in Xcode just right.

How to read string from keyboard using C?

The following code can be used to read the input string from a user. But it's space is limited to 64.

char word[64] = { '\0' };  //initialize all elements with '\0'
int i = 0;
while ((word[i] != '\n')&& (i<64))
    scanf_s("%c", &word[i++], 1);

Convert a RGB Color Value to a Hexadecimal String

This is an adapted version of the answer given by Vivien Barousse with the update from Vulcan applied. In this example I use sliders to dynamically retreive the RGB values from three sliders and display that color in a rectangle. Then in method toHex() I use the values to create a color and display the respective Hex color code.

This example does not include the proper constraints for the GridBagLayout. Though the code will work, the display will look strange.

public class HexColor

  public static void main (String[] args)
   JSlider sRed = new JSlider(0,255,1);
   JSlider sGreen = new JSlider(0,255,1);
   JSlider sBlue = new JSlider(0,255,1);
   JLabel hexCode = new JLabel();
   JPanel myPanel = new JPanel();
   GridBagLayout layout = new GridBagLayout();
   JFrame frame = new JFrame();

   //set frame to organize components using GridBagLayout 

   //create gray filled rectangle 

   //In practice this code is replicated and applied to sGreen and sBlue. 
   //For the sake of brevity I only show sRed in this post.
         new ChangeListener()
             public void stateChanged(ChangeEvent e){
   //add each component to JFrame
} //end of main

  //creates JPanel filled rectangle
  protected void paintComponent(Graphics g)
      g.drawRect(360, 300, 10, 10);
      g.fillRect(360, 300, 10, 10);

  //changes the display color in JPanel
  private Color changeColor()
    int r = sRed.getValue();
    int b = sBlue.getValue();
    int g = sGreen.getValue();
    Color c;
    return  c = new Color(r,g,b);

  //Displays hex representation of displayed color
  private String toHex()
      Integer r = sRed.getValue();
      Integer g = sGreen.getValue();
      Integer b = sBlue.getValue();
      Color hC;
      hC = new Color(r,g,b);
      String hex = Integer.toHexString(hC.getRGB() & 0xffffff);
      while(hex.length() < 6){
          hex = "0" + hex;
      hex = "Hex Code: #" + hex;
      return hex;

A huge thank you to both Vivien and Vulcan. This solution works perfectly and was super simple to implement.

How to make html <select> element look like "disabled", but pass values?

My solution was to create a disabled class in CSS:

.disabled {
    pointer-events: none;
    cursor: not-allowed;

and then your select would be:

<select name="sel" class="disabled">

The user would be unable to pick any values but the select value would still be passed on form submission.

Want to move a particular div to right

This will do the job:

<div style="position:absolute; right:0;">Hello world</div>

What, why or when it is better to choose cshtml vs aspx?

While the syntax is certainly different between Razor (.cshtml/.vbhtml) and WebForms (.aspx/.ascx), (Razor's being the more concise and modern of the two), nobody has mentioned that while both can be used as View Engines / Templating Engines, traditional ASP.NET Web Forms controls can be used on any .aspx or .ascx files, (even in cohesion with an MVC architecture).

This is relevant in situations where long standing solutions to a problem have been established and packaged into a pluggable component (e.g. a large-file uploading control) and you want to use it in an MVC site. With Razor, you can't do this. However, you can execute all of the same backend-processing that you would use with a traditional ASP.NET architecture with a Web Form view.

Furthermore, ASP.NET web forms views can have Code-Behind files, which allows embedding logic into a separate file that is compiled together with the view. While the software development community is growing to be see tightly coupled architectures and the Smart Client pattern as bad practice, it used to be the main way of doing things and is still very much possible with .aspx/.ascx files. Razor, intentionally, has no such quality.

"Uncaught (in promise) undefined" error when using with=location in Facebook Graph API query

The reject actually takes one parameter: that's the exception that occurred in your code that caused the promise to be rejected. So, when you call reject() the exception value is undefined, hence the "undefined" part in the error that you get.

You do not show the code that uses the promise, but I reckon it is something like this:

var promise = doSth();
promise.then(function() { doSthHere(); });

Try adding an empty failure call, like this:

promise.then(function() { doSthHere(); }, function() {});

This will prevent the error to appear.

However, I would consider calling reject only in case of an actual error, and also... having empty exception handlers isn't the best programming practice.

MySQL: Check if the user exists and drop it

Regarding @Cherian's answer, the following lines can be removed:


This was a bug pre 5.1.23. After that version these are no longer required. So, for copy/paste convenience, here is the same with the above lines removed. Again, for example purposes "test" is the user and "databaseName" is the database; and this was from this bug.

DROP PROCEDURE IF EXISTS databaseName.drop_user_if_exists ;
CREATE PROCEDURE databaseName.drop_user_if_exists()
  INTO foo
    FROM mysql.user
      WHERE User = 'test' and  Host = 'localhost';
   IF foo > 0 THEN
         DROP USER 'test'@'localhost' ;
END ;$$
CALL databaseName.drop_user_if_exists() ;
DROP PROCEDURE IF EXISTS databaseName.drop_users_if_exists ;

CREATE USER 'test'@'localhost' IDENTIFIED BY 'a';
GRANT ALL PRIVILEGES  ON databaseName.* TO 'test'@'localhost'

How do I compile a .c file on my Mac?

You'll need to get a compiler. The easiest way is probably to install XCode development environment from the CDs/DVDs you got with your Mac, which will give you gcc. Then you should be able compile it like

gcc -o mybinaryfile mysourcefile.c

How to enable MySQL Query Log?

In phpMyAdmin 4.0, you go to Status > Monitor. In there you can enable the slow query log and general log, see a live monitor, select a portion of the graph, see the related queries and analyse them.

Disabling of EditText in Android

As android:editable="false" is depricated.You can use InputType TYPE_NULL on EditText

use like this :


LoDash: Get an array of values from an array of object properties

If you are using native javascript then you can use this code -

let ids =, index) {


console.log(ids); //[12, 14, 16, 18]

Create PDF from a list of images

How about this??

from fpdf import FPDF
from PIL import Image
import glob
import os

# set here
image_directory = '/path/to/imageDir'
extensions = ('*.jpg','*.png','*.gif') #add your image extentions
# set 0 if you want to fit pdf to image
# unit : pt
margin = 10

for ext in extensions:

for imagePath in imagelist:
    cover =
    width, height = cover.size

pdf = FPDF(unit="pt", format=[width + 2*margin, height + 2*margin])

pdf.image(imagePath, margin, margin)

destination = os.path.splitext(imagePath)[0]
pdf.output(destination + ".pdf", "F")

ERROR 1452: Cannot add or update a child row: a foreign key constraint fails

You must delete data in the child table which does not have any corresponding foreign key value to the parent table primary key .Or delete all data from the child table then insert new data having the same foreign key value as the primary key in the parent table . That should work . Here also a youtube video

What is JNDI? What is its basic use? When is it used?

JNDI in layman's terms is basically an Interface for being able to get instances of internal/External resources such as


or any other type defined by a JCA resource adapter. It provides a syntax in being able to create access whether they are internal or external. i.e (comp/env in this instance means where component/environment, there are lots of other syntax):


Check if an excel cell exists on another worksheet in a column - and return the contents of a different column

You can use following formulas.

For Excel 2007 or later:


For Excel 2003:

=IF(ISERROR(MATCH(D3,List!A:A, 0)), "No Match", VLOOKUP(D3,List!A:C,3,FALSE))

Note, that

  • I'm using List!A:C in VLOOKUP and returns value from column ? 3
  • I'm using 4th argument for VLOOKUP equals to FALSE, in that case VLOOKUP will only find an exact match, and the values in the first column of List!A:C do not need to be sorted (opposite to case when you're using TRUE).

The representation of if-elseif-else in EL using JSF

You can use EL if you want to work as IF:

<h:outputLabel value="#{row==10? '10' : '15'}"/>

Changing styles or classes:

style="#{test eq testMB.test? 'font-weight:bold' : 'font-weight:normal'}"

class="#{test eq testMB.test? 'divRred' : 'divGreen'}"

BACKUP LOG cannot be performed because there is no current database backup

Click Right Click On Your Database The Press tasks>Back Up and take a back up from your database before restore your database i'm using this way to solve this Problem

How to read text file in JavaScript

This can be done quite easily using javascript XMLHttpRequest() class (AJAX):

function FileHelper()

    FileHelper.readStringFromFileAtPath = function(pathOfFileToReadFrom)
        var request = new XMLHttpRequest();"GET", pathOfFileToReadFrom, false);
        var returnValue = request.responseText;

        return returnValue;


var text = FileHelper.readStringFromFileAtPath ( "mytext.txt" );

Android camera android.hardware.Camera deprecated

Now we have to use android.hardware.camera2 as android.hardware.Camera is deprecated which will only work on API >23 FlashLight

   public class MainActivity extends AppCompatActivity {

     Button button;

     Boolean light=true;

     CameraDevice cameraDevice;

     private CameraManager cameraManager;

     private CameraCharacteristics cameraCharacteristics;

     String cameraId;

    protected void onCreate(Bundle savedInstanceState) {
        cameraManager = (CameraManager) 
        try {
          cameraId = cameraManager.getCameraIdList()[0];
        } catch (CameraAccessException e) {
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                    try {

                    } catch (CameraAccessException e) {

                    else {

                    try {

                    } catch (CameraAccessException e) {



How to programmatically send SMS on the iPhone?

[[UIApplication sharedApplication]openURL:[NSURL URLWithString:@"sms:number"]] 

This would be the best and short way to do it.

Bootstrap 3.0: How to have text and input on same line?

just give mother of div "class="col-lg-12""

<div class="form-group">
<div class="row">
    <div class="col-xs-3">
        <label for="class_type"><h2><span class=" label label-primary">Class Type</span></h2></label>
    <div class="col-xs-2">
        <select name="class_type" id="class_type" class="  form-control input-lg" style="width:200px" autocomplete="off">
            <option >Economy</option>
            <option >Premium Economy</option>
            <option >Club World</option>
            <option >First Class</option>

it will be

<div class="form-group">
<div class="col-lg-12">
  <div class="row">
    <div class="col-xs-3">
        <label for="class_type"><h2><span class=" label label-primary">Class Type</span></h2></label>
    <div class="col-xs-2">
        <select name="class_type" id="class_type" class="  form-control input-lg" style="width:200px" autocomplete="off">
            <option >Economy</option>
            <option >Premium Economy</option>
            <option >Club World</option>
            <option >First Class</option>

How do I set GIT_SSL_NO_VERIFY for specific repos only?

This question keeps coming up and I did not find a satisfying result yet, so here is what worked for me (based on a previous answer, which is not working):

My server is with a self-signed certificate.

First run git config --system --edit (from an elevated command prompt, change --system to --global if you want to do it for just your user), then insert the following snippet after any previous [http] sections:

[http ""]
        sslVerify = false

Then check if you did everything correctly:

> git config --type=bool --get-urlmatch http.sslVerify

Creating executable files in Linux

It's really not that big of a deal. You could just make a script with the single command:

chmod a+x *.pl

And run the script after creating a perl file. Alternatively, you could open a file with a command like this:

touch && chmod a+x && vi # choose your favorite editor

Difference between View and Request scope in managed beans

A @ViewScoped bean lives exactly as long as a JSF view. It usually starts with a fresh new GET request, or with a navigation action, and will then live as long as the enduser submits any POST form in the view to an action method which returns null or void (and thus navigates back to the same view). Once you refresh the page, or return a non-null string (even an empty string!) navigation outcome, then the view scope will end.

A @RequestScoped bean lives exactly as long a HTTP request. It will thus be garbaged by end of every request and recreated on every new request, hereby losing all changed properties.

A @ViewScoped bean is thus particularly more useful in rich Ajax-enabled views which needs to remember the (changed) view state across Ajax requests. A @RequestScoped one would be recreated on every Ajax request and thus fail to remember all changed view state. Note that a @ViewScoped bean does not share any data among different browser tabs/windows in the same session like as a @SessionScoped bean. Every view has its own unique @ViewScoped bean.

See also:

How does Facebook disable the browser's integrated Developer Tools?

I couldn't get it to trigger that on any page. A more robust version of this would do it:

window.console.log = function(){
    console.error('The developer console is temp...');
    window.console.log = function() {
        return false;


To style the output: Colors in JavaScript console

Edit Thinking @joeldixon66 has the right idea: Disable JavaScript execution from console « ::: KSpace :::

Check if null Boolean is true results in exception

Boolean types can be null. You need to do a null check as you have set it to null.

if (bool != null && bool)

How to get a variable type in Typescript?

I'd like to add that TypeGuards only work on strings or numbers, if you want to compare an object use instanceof

if( instanceof UUID) {

How to add button in ActionBar(Android)?

you have to create an entry inside res/menu,override onCreateOptionsMenu and inflate it

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(, menu);
    return true;

an entry for the menu could be:

<menu xmlns:android="" >

Click in OK button inside an Alert (Selenium IDE)

To click the "ok" button in an alert box:


How can I pass arguments to a batch file?

FOR %%A IN (%*) DO (
    REM Now your batch file handles %%A instead of %1
    REM No need to use SHIFT anymore.
    ECHO %%A

This loops over the batch parameters (%*) either they are quoted or not, then echos each parameter.

How to convert a String into an array of Strings containing one character each

Use toCharArray() method. It splits the string into an array of characters:

String str = "aabbab";
char[] chs = str.toCharArray();

Making Maven run all tests, even when some fail

Try to add the following configuration for surefire plugin in your pom.xml of root project:


How do I use reflection to invoke a private method?

Are you absolutely sure this can't be done through inheritance? Reflection is the very last thing you should look at when solving a problem, it makes refactoring, understanding your code, and any automated analysis more difficult.

It looks like you should just have a DrawItem1, DrawItem2, etc class that override your dynMethod.

Ajax passing data to php script

You are sending a POST AJAX request so use $albumname = $_POST['album']; on your server to fetch the value. Also I would recommend you writing the request like this in order to ensure proper encoding:

    type: 'POST',  
    url: 'test.php', 
    data: { album: this.title },
    success: function(response) {

or in its shorter form:

$.post('test.php', { album: this.title }, function() {

and if you wanted to use a GET request:

    type: 'GET',
    url: 'test.php', 
    data: { album: this.title },
    success: function(response) {

or in its shorter form:

$.get('test.php', { album: this.title }, function() {

and now on your server you wil be able to use $albumname = $_GET['album'];. Be careful though with AJAX GET requests as they might be cached by some browsers. To avoid caching them you could set the cache: false setting.

How do I use CMake?

Yes, cmake and make are different programs. cmake is (on Linux) a Makefile generator (and Makefile-s are the files driving the make utility). There are other Makefile generators (in particular configure and autoconf etc...). And you can find other build automation programs (e.g. ninja).

How to search a string in String array

Well, something is going to have to look, and looping is more efficient than recursion (since tail-end recursion isn't fully implemented)... so if you just don't want to loop yourself, then either of:

bool has = arr.Contains(var); // .NET 3.5


bool has = Array.IndexOf(arr, var) >= 0;

For info: avoid names like var - this is a keyword in C# 3.0.

X-Frame-Options Allow-From multiple domains

As per the MDN Specifications, X-Frame-Options: ALLOW-FROM is not supported in Chrome and support is unknown in Edge and Opera.

Content-Security-Policy: frame-ancestors overrides X-Frame-Options (as per this W3 spec), but frame-ancestors has limited compatibility. As per these MDN Specs, it's not supported in IE or Edge.

Remove .php extension with .htaccess

To remove the .php extension from a PHP file for example to Follow these step . Open .htaccess(create new one if not exists) file from root of your website, and add the following code.

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.php [NC,L]

To remove the .html extension from a html file for example to Follow these step .

Open .htaccess(create new one if not exists) file from root of your website, and add the following code.

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.html [NC,L]

Reference: How to Remove php Extention from URL

Android Studio: Module won't show up in "Edit Configuration"

This mainly happens when you copy a library project and try to build it. The solution would be to add

apply plugin: ''

in the build.gradle file, instead of

apply plugin: ''

Then do a gradle sync

Check if option is selected with jQuery, if not select a default

If you need to explicitly check each option to see if any have the "selected" attribute you can do this. Otherwise using option:selected you'll get the value for the first default option.

var viewport_selected = false;      
$('#viewport option').each(function() {
    if ($(this).attr("selected") == "selected") {
        viewport_selected = true;

How can I commit files with git?

The command for commiting all changed files:

git commit -a -m 'My commit comments'

-a = all edited files

-m = following string is a comment.

This will commit to your local drives / folders repo. If you want to push your changes to a git server / remotely hosted server, after the above command type:

git push

GitHub's cheat sheet is quite handy.

Access to ES6 array element index inside for-of loop

Also you can use JavaScript to solve your problem

iterate(item, index) {
    console.log(`${item} has index ${index}`);
    //Do what you want...

readJsonList() {    
    //it could be any array list.

how to open a page in new tab on button click in

In either on button click or on link button click, this will work.

System.Web.UI.ScriptManager.RegisterClientScriptBlock(Me, Me.GetType(), "openModal", "'CertificatePrintViewAll.aspx' ,'_blank');", True)

MySQL error 2006: mysql server has gone away

This might be a problem of your .sql file size.

If you are using xampp. Go to the xampp control panel -> Click MySql config -> Open my.ini.

Increase the packet size.

max_allowed_packet = 2M -> 10M

Convert pandas timezone-aware DateTimeIndex to naive timestamp, but in certain timezone

The most important thing is add tzinfo when you define a datetime object.

from datetime import datetime, timezone
from tzinfo_examples import HOUR, Eastern
u0 = datetime(2016, 3, 13, 5, tzinfo=timezone.utc)
for i in range(4):
     u = u0 + i*HOUR
     t = u.astimezone(Eastern)
     print(u.time(), 'UTC =', t.time(), t.tzname())

Getting an element from a Set

What about using the Arrays class ?

import java.util.Arrays;
import java.util.List;
import java.util.HashSet;
import java.util.Arrays;

public class MyClass {
    public static void main(String args[]) {
        Set mySet = new HashSet();
        List list = Arrays.asList(mySet.toArray());
        Object o0 = list.get(0);
        Object o1 = list.get(1);
        System.out.println("items " + o0+","+o1);

items one,two

How to set focus on a view when a layout is created and displayed?

to change the focus make the textView in xml focusable


and in java in on create


or simply hide the keyboard

public void hideKeyBoard(Activity act) {
    InputMethodManager imm = (InputMethodManager) act.getSystemService(Context.INPUT_METHOD_SERVICE);

How to select all instances of a variable and edit variable name in Sublime

Just in case anyone else stumbled on this question while looking for a way to replace a string across multiple files, it is Command+Shift+F

How do you remove columns from a data.frame?

If you have a vector of names already,which there are several ways to create, you can easily use the subset function to keep or drop an object.

dat2 <- subset(dat, select = names(dat) %in% c(KEEP))

In this case KEEP is a vector of column names which is pre-created. For example:

#sample data via Brandon Bertelsen
df <- data.frame(a=rnorm(100),

#creating the initial vector of names
df1 <- as.matrix(as.character(names(df)))

#retaining only the name values you want to keep
KEEP <- as.vector(df1[c(1:3,5,6),])

#subsetting the intial dataset with the object KEEP
df3 <- subset(df, select = names(df) %in% c(KEEP))

Which results in:

> head(df)
            a          b           c          d
1  1.05526388  0.6316023 -0.04230455 -0.1486299
2 -0.52584236  0.5596705  2.26831758  0.3871873
3  1.88565261  0.9727644  0.99708383  1.8495017
4 -0.58942525 -0.3874654  0.48173439  1.4137227
5 -0.03898588 -1.5297600  0.85594964  0.7353428
6  1.58860643 -1.6878690  0.79997390  1.1935813
            e           f           g
1 -1.42751190  0.09842343 -0.01543444
2 -0.62431091 -0.33265572 -0.15539472
3  1.15130591  0.37556903 -1.46640276
4 -1.28886526 -0.50547059 -2.20156926
5 -0.03915009 -1.38281923  0.60811360
6 -1.68024349 -1.18317733  0.42014397

> head(df3)
        a          b           c           e
1  1.05526388  0.6316023 -0.04230455 -1.42751190
2 -0.52584236  0.5596705  2.26831758 -0.62431091
3  1.88565261  0.9727644  0.99708383  1.15130591
4 -0.58942525 -0.3874654  0.48173439 -1.28886526
5 -0.03898588 -1.5297600  0.85594964 -0.03915009
6  1.58860643 -1.6878690  0.79997390 -1.68024349
1  0.09842343
2 -0.33265572
3  0.37556903
4 -0.50547059
5 -1.38281923
6 -1.18317733

Use IntelliJ to generate class diagram

Now there is an official way to add "PlantUML integration" plugin to your JetBrains product.

Installation steps please refer:

How to write a file or data to an S3 object using boto3

You may use the below code to write, for example an image to S3 in 2019. To be able to connect to S3 you will have to install AWS CLI using command pip install awscli, then enter few credentials using command aws configure:

import urllib3
import uuid
from pathlib import Path
from io import BytesIO
from errors import custom_exceptions as cex

BUCKET_NAME = "xxx.yyy.zzz"
POSTERS_BASE_PATH = "assets/wallcontent"

class S3(object):
    def __init__(self):
        self.client = boto3.client('s3')
        self.bucket_name = BUCKET_NAME
        self.posters_base_path = POSTERS_BASE_PATH

    def __download_image(self, url):
        manager = urllib3.PoolManager()
            res = manager.request('GET', url)
        except Exception:
            print("Could not download the image from URL: ", url)
            raise cex.ImageDownloadFailed
        return BytesIO(  # any file-like object that implements read()

    def upload_image(self, url):
            image_file = self.__download_image(url)
        except cex.ImageDownloadFailed:
            raise cex.ImageUploadFailed

        extension = Path(url).suffix
        id = uuid.uuid1().hex + extension
        final_path = self.posters_base_path + "/" + id
        except Exception:
            print("Image Upload Error for URL: ", url)
            raise cex.ImageUploadFailed

        return CLOUDFRONT_BASE_URL + id

Get the current time in C

Copy-pasted from here:

/* localtime example */
#include <stdio.h>
#include <time.h>

int main ()
  time_t rawtime;
  struct tm * timeinfo;

  time ( &rawtime );
  timeinfo = localtime ( &rawtime );
  printf ( "Current local time and date: %s", asctime (timeinfo) );
  return 0;

(just add void to the main() arguments list in order for this to work in C)

CALL command vs. START with /WAIT option


Calls one batch program from another without stopping the parent batch program. The call command accepts labels as the target of the call. Call has no effect at the command-line when used outside of a script or batch file.


Starts a separate Command Prompt window to run a specified program or command. Used without parameters, start opens a second command prompt window.

How can I see the raw SQL queries Django is running?

See the docs FAQ: "How can I see the raw SQL queries Django is running?"

django.db.connection.queries contains a list of the SQL queries:

from django.db import connection

Querysets also have a query attribute containing the query to be executed:

print(MyModel.objects.filter(name="my name").query)

Note that the output of the query is not valid SQL, because:

"Django never actually interpolates the parameters: it sends the query and the parameters separately to the database adapter, which performs the appropriate operations."

From Django bug report #17741.

Because of that, you should not send query output directly to a database.

Visual Studio 2008 Product Key in Registry?

For Visual Studio 2005:

If you do have an installed Visual Studio 2005 however, and want to find out the serial number you’ve used to install it because you don’t have a clue where you put that shiny sticker, you can. It is, like most things in Windows, in the registry.


In order to convert the value in that key to an actual serial number you have to put a dash ( – ) after evert 5 characters of the code.


For Visual Studio 2008 it's supposed to be:


However I noted that the the Data field for PIDKEY is only filled in the 1000.0x000 (or 2000.0x000) sub folder of the above paths.

Creating a .p12 file

The openssl documentation says that file supplied as the -in argument must be in PEM format.

Turns out that, contrary to the CA's manual, the certificate returned by the CA which I stored in myCert.cer is not PEM format rather it is PKCS7.

In order to create my .p12, I had to first convert the certificate to PEM:

openssl pkcs7 -in myCert.cer -print_certs -out certs.pem

and then execute

openssl pkcs12 -export -out keyStore.p12 -inkey myKey.pem -in certs.pem

Reading from text file until EOF repeats last line

Just follow closely the chain of events.

  • Grab 10
  • Grab 20
  • Grab 30
  • Grab EOF

Look at the second-to-last iteration. You grabbed 30, then carried on to check for EOF. You haven't reached EOF because the EOF mark hasn't been read yet ("binarically" speaking, its conceptual location is just after the 30 line). Therefore you carry on to the next iteration. x is still 30 from previous iteration. Now you read from the stream and you get EOF. x remains 30 and the ios::eofbit is raised. You output to stderr x (which is 30, just like in the previous iteration). Next you check for EOF in the loop condition, and this time you're out of the loop.

Try this:

while (true) {
    int x;
    iFile >> x;
    if( iFile.eof() ) break;
    cerr << x << endl;

By the way, there is another bug in your code. Did you ever try to run it on an empty file? The behaviour you get is for the exact same reason.

OpenCV - Apply mask to a color image

The other methods described assume a binary mask. If you want to use a real-valued single-channel grayscale image as a mask (e.g. from an alpha channel), you can expand it to three channels and then use it for interpolation:

assert len(mask.shape) == 2 and issubclass(mask.dtype.type, np.floating)
assert len(foreground_rgb.shape) == 3
assert len(background_rgb.shape) == 3

alpha3 = np.stack([mask]*3, axis=2)
blended = alpha3 * foreground_rgb + (1. - alpha3) * background_rgb

Note that mask needs to be in range 0..1 for the operation to succeed. It is also assumed that 1.0 encodes keeping the foreground only, while 0.0 means keeping only the background.

If the mask may have the shape (h, w, 1), this helps:

alpha3 = np.squeeze(np.stack([np.atleast_3d(mask)]*3, axis=2))

Here np.atleast_3d(mask) makes the mask (h, w, 1) if it is (h, w) and np.squeeze(...) reshapes the result from (h, w, 3, 1) to (h, w, 3).

Maximum number of rows of CSV data in excel sheet

In my memory, excel (versions >= 2007) limits the power 2 of 20: 1.048.576 lines.

Csv is over to this boundary, like ordinary text file. So you will be care of the transfer between two formats.

How to check if a character in a string is a digit or letter

I have coded a sample program that checks if a string contains a number in it! I guess it will serve for this purpose as well.

public class test {
    public static void main(String[] args) {
        String c;
        boolean b;

        System.out.println("Enter the value");
        Scanner s = new Scanner(;
        c =;
        b = containsNumber(c);
        try {
            if (b == true) {
                throw new CharacterFormatException();
            } else {
                System.out.println("Valid String \t" + c);
        } catch (CharacterFormatException ex) {
            System.out.println("Exception Raised-Contains Number");


    static boolean containsNumber(String c) {
        char[] ch = new char[10];
        ch = c.toCharArray();

        for (int i = 0; i < ch.length; i++) {
            if ((ch[i] >= 48) && (ch[i] <= 57)) {
                return true;
        return false;

CharacterFormatException is a user defined Exception. Suggest me if any changes can be made.

Xcode 9 Swift Language Version (SWIFT_VERSION)

I just got this after creating a new Objective-C project in Xcode 10, after I added a Core Data model file to the project.

I found two ways to fix this:

  1. The Easy Way: Open the Core Data model's File Inspector (??-1) and change the language from Swift to Objective-C

Change Core Data model language

  1. Longer and more dangerous method

The model contains a "contents" file with this line:

<model type="" documentVersion="1.0" lastSavedToolsVersion="14460.32" systemVersion="17G5019" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">

In there is a sourceLanguage="Swift" entry. Change it to sourceLanguage="Objective-C" and the error goes away.

To find the "contents" file, right click on the .xcdatamodeld in Xcode and do "Show in Finder". Right-click on the actual (Finder) file and do "Show Package Contents"

Also: Changing the model's language will stop Xcode from generating managed object subclass files in Swift.

javascript - match string against the array of regular expressions

You could use .test() which returns a boolean value when is find what your looking for in another string:

var thisExpressions = [ '/something/', '/something_else/', '/and_something_else/'];
var thisString = new RegExp('\\b' + 'else' + '\\b', 'i');
var FoundIt = thisString.test(thisExpressions);  
if (FoundIt) { /* DO STUFF */ }

How to scroll to bottom in react?

  1. Reference your messages container.

    <div ref={(el) => { this.messagesContainer = el; }}> YOUR MESSAGES </div>
  2. Find your messages container and make its scrollTop attribute equal scrollHeight:

    scrollToBottom = () => {
        const messagesContainer = ReactDOM.findDOMNode(this.messagesContainer);
        messagesContainer.scrollTop = messagesContainer.scrollHeight;
  3. Evoke above method on componentDidMount and componentDidUpdate.

    componentDidMount() {
    componentDidUpdate() {

This is how I am using this in my code:

 export default class StoryView extends Component {

    constructor(props) {
        this.scrollToBottom = this.scrollToBottom.bind(this);

    scrollToBottom = () => {
        const messagesContainer = ReactDOM.findDOMNode(this.messagesContainer);
        messagesContainer.scrollTop = messagesContainer.scrollHeight;

    componentDidMount() {

    componentDidUpdate() {

    render() {
        return (
                <Grid className="storyView">
                        <div className="codeView">
                            <Col md={8} mdOffset={2}>
                                <div ref={(el) => { this.messagesContainer = el; }} 
                               (message, i) {
                                            return (
                                                <div key={i}>
                                                    <div className="bubble" >
                                        }, this)

How to reset Django admin password?

One of the best ways to retrieve the username and password is to view and update them. The User Model provides a perfect way to do so.

In this case, I'm using Django 1.9

  1. Navigate to your root directory i,e. where you "" file is located using your console or other application such as Git.

  2. Retrieve the Python shell using the command "python shell".

  3. Import the User Model by typing the following command "from django.contrib.auth.models import User"

  4. Get all the users by typing the following command "users = User.objects.all()"

  5. Print a list of the users For Python 2 users use the command "print users" For Python 3 users use the command "print(users)" The first user is usually the admin.

  6. Select the user you wish to change their password e.g.

    "user = users[0]"

  7. Set the password


  8. Save the new password


Start the server and log in using the username and the updated password.

Configuration Error: <compilation debug="true" targetFramework="4.0"> ASP.NET MVC3

You could be using the 32 bit version, so you should prob try at the command line from the Framework (not Framework64) folder.

IE Did you try it from C:\Windows\Microsoft.NET\Framework\v4.0.30319 rather than the 64 version? If you ref 32 bit libs you can be forced to 32 bit version (some other reasons as well if I recall)

Is your site a child of another site in IIS?

For more details on this (since it applies to various types of apps running on .NET) see Scott's post at:

32-bit and 64-bit confusion around x86 and x64 and the .NET Framework and CLR

Can't install Scipy through pip

If you are using CentOS you need to install lapack-devel like so:

 $ yum install lapack-devel

lvalue required as left operand of assignment

I found that an answer to this issue when dealing with math is that the operator on the left hand side must be the variable you are trying to change. The logic cannot come first.

coin1 + coin2 + coin3 = coinTotal; // Wrong

coinTotal = coin1 + coin2 + coin3; // Right

This isn't a direct answer to your question but it might be helpful to future people who google the same thing I googled.

How to secure phpMyAdmin

You can use the following command :

$ grep "phpmyadmin" $path_to_access.log | grep -Po "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}" | sort | uniq | xargs -I% sudo iptables -A INPUT -s % -j DROP 


Make sure your IP isn't listed before piping through iptables drop!!

This will first find all lines in $path_to_access.log that have phpmyadmin in them,

then grep out the ip address from the start of the line,

then sort and unique them,

then add a rule to drop them in iptables

Again, just edit in echo % at the end instead of the iptables command to make sure your IP isn't in there. Don't inadvertently ban your access to the server!


You may need to change the grep part of the command if you're on mac or any system that doesn't have grep -P. I'm not sure if all systems start with xargs, so that might need to be installed too. It's super useful anyway if you do a lot of bash.

Centering text in a table in Twitter Bootstrap

One of the main feature of Bootstrap is that it alleviates the use of !important tag. Using the above answer would defeat the purpose. You can easily customise bootstrap by modifying the classes in your own css file and linking it after including the boostrap css.

Check if an array contains duplicate values

You got the return values the wrong way round:

  • As soon as you find two values that are equal, you can conclude that the array is not unique and return false.

  • At the very end, after you've checked all the pairs, you can return true.

If you do this a lot, and the arrays are large, you might want to investigate the possibility of sorting the array and then only comparing adjacent elements. This will have better asymptotic complexity than your current method.

How do I extract data from JSON with PHP?

We can decode json string into array using json_decode function in php

1) json_decode($json_string) // it returns object

2) json_decode($json_string,true) // it returns array

$json_string = '{
    "type": "donut",
    "name": "Cake",
    "toppings": [
        { "id": "5002", "type": "Glazed" },
        { "id": "5006", "type": "Chocolate with Sprinkles" },
        { "id": "5004", "type": "Maple" }
$array = json_decode($json_string,true);

echo $array['type']; //it gives donut

What is the => assignment in C# in a property signature

What you're looking at is an expression-bodied member not a lambda expression.

When the compiler encounters an expression-bodied property member, it essentially converts it to a getter like this:

public int MaxHealth
        return Memory[Address].IsValid ? Memory[Address].Read<int>(Offs.Life.MaxHp) : 0;

(You can verify this for yourself by pumping the code into a tool called TryRoslyn.)

Expression-bodied members - like most C# 6 features - are just syntactic sugar. This means that they don’t provide functionality that couldn't otherwise be achieved through existing features. Instead, these new features allow a more expressive and succinct syntax to be used

As you can see, expression-bodied members have a handful of shortcuts that make property members more compact:

  • There is no need to use a return statement because the compiler can infer that you want to return the result of the expression
  • There is no need to create a statement block because the body is only one expression
  • There is no need to use the get keyword because it is implied by the use of the expression-bodied member syntax.

I have made the final point bold because it is relevant to your actual question, which I will answer now.

The difference between...

// expression-bodied member property
public int MaxHealth => x ? y:z;


// field with field initializer
public int MaxHealth = x ? y:z;

Is the same as the difference between...

public int MaxHealth
        return x ? y:z;


public int MaxHealth = x ? y:z;

Which - if you understand properties - should be obvious.

Just to be clear, though: the first listing is a property with a getter under the hood that will be called each time you access it. The second listing is is a field with a field initializer, whose expression is only evaluated once, when the type is instantiated.

This difference in syntax is actually quite subtle and can lead to a "gotcha" which is described by Bill Wagner in a post entitled "A C# 6 gotcha: Initialization vs. Expression Bodied Members".

While expression-bodied members are lambda expression-like, they are not lambda expressions. The fundamental difference is that a lambda expression results in either a delegate instance or an expression tree. Expression-bodied members are just a directive to the compiler to generate a property behind the scenes. The similarity (more or less) starts and end with the arrow (=>).

I'll also add that expression-bodied members are not limited to property members. They work on all these members:

  • Properties
  • Indexers
  • Methods
  • Operators

Added in C# 7.0

However, they do not work on these members:

  • Nested Types
  • Events
  • Fields

LDAP filter for blank (empty) attribute

Semantically there is no difference between these cases in LDAP.

What are the default access modifiers in C#?

Internal is the default modifier

Can I pass parameters by reference in Java?

Java is always pass by value.

When you pass a primitive it's a copy of the value, when you pass an object it's a copy of the reference pointer.

Where is svcutil.exe in Windows 7?

Try to generate the proxy class via SvcUtil.exe with command


svcutil.exe /language:<type> /out:<name>.cs /config:<name>.config http://<host address>:<port>


svcutil.exe /language:cs /out:generatedProxy.cs /config:app.config http://localhost:8000/ServiceSamples/myService1

To check if service is available try in your IE URL from example upon without myService1 postfix

How to align absolutely positioned element to center?

position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 0;
margin: auto;

How can I change a button's color on hover?

Seems your selector is wrong, try using:

     background: #383;

Your code

a.button a:hover

Means it is going to search for an a element inside a with class button.

Using OR in SQLAlchemy

From the tutorial:

from sqlalchemy import or_
filter(or_( == 'ed', == 'wendy'))

How can I solve equations in Python?

How about SymPy? Their solver looks like what you need. Have a look at their source code if you want to build the library yourself…

C++ Boost: undefined reference to boost::system::generic_category()

After testing the proposed solutions described above, I found only these few of lines would work.

I am using Ubuntu 16.04.

cmake_minimum_required(VERSION 3.13)

add_executable(myProject main.cpp)

find_package(Boost 1.58.0 REQUIRED COMPONENTS system filesystem)
target_link_libraries(myProject ${Boost_LIBRARIES})

int to string in MySQL

If you have a column called "col1" which is int, you cast it to String like this:


e.g. this allows you to check an int value is containing another value (here 9) like this:

CONVERT(col1,char) LIKE '%9%'

Show values from a MySQL database table inside a HTML table on a webpage

Try this: (Completely Dynamic...)

$host    = "localhost";
$user    = "username_here";
$pass    = "password_here";
$db_name = "database_name_here";

//create connection
$connection = mysqli_connect($host, $user, $pass, $db_name);

//test if connection failed
    die("connection failed: "
        . mysqli_connect_error()
        . " (" . mysqli_connect_errno()
        . ")");

//get results from database
$result = mysqli_query($connection,"SELECT * FROM products");
$all_property = array();  //declare an array for saving property

//showing property
echo '<table class="data-table">
        <tr class="data-heading">';  //initialize table tag
while ($property = mysqli_fetch_field($result)) {
    echo '<td>' . $property->name . '</td>';  //get field name for header
    array_push($all_property, $property->name);  //save those to array
echo '</tr>'; //end tr tag

//showing all data
while ($row = mysqli_fetch_array($result)) {
    echo "<tr>";
    foreach ($all_property as $item) {
        echo '<td>' . $row[$item] . '</td>'; //get items using property value
    echo '</tr>';
echo "</table>";

CSS text-align: center; is not centering things

I assume you want all the items next to each other, and the whole thing to be centered horizontally.

li elements are display: block by default, taking up all the horizontal space.


div#footer ul li { display: inline }

once you've done that, you probably want to get rid of the list's bullets:

div#footer ul { list-style-type: none; padding: 0px; margin: 0px }

Does dispatch_async(dispatch_get_main_queue(), ^{...}); wait until done?

If you want to run a single independent queued operation and you’re not concerned with other concurrent operations, you can use the global concurrent queue:

dispatch_queue_t globalConcurrentQueue =
dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

This will return a concurrent queue with the given priority as outlined in the documentation:

DISPATCH_QUEUE_PRIORITY_HIGH Items dispatched to the queue will run at high priority, i.e. the queue will be scheduled for execution before any default priority or low priority queue.

DISPATCH_QUEUE_PRIORITY_DEFAULT Items dispatched to the queue will run at the default priority, i.e. the queue will be scheduled for execution after all high priority queues have been scheduled, but before any low priority queues have been scheduled.

DISPATCH_QUEUE_PRIORITY_LOW Items dispatched to the queue will run at low priority, i.e. the queue will be scheduled for execution after all default priority and high priority queues have been scheduled.

DISPATCH_QUEUE_PRIORITY_BACKGROUND Items dispatched to the queue will run at background priority, i.e. the queue will be scheduled for execution after all higher priority queues have been scheduled and the system will run items on this queue on a thread with background status as per setpriority(2) (i.e. disk I/O is throttled and the thread’s scheduling priority is set to lowest value).

LOAD DATA INFILE Error Code : 13

I know, this is an old thread but there are still many folks facing problems with LOAD DATA INFILE!

There are quite a few answers which are great but for me, none of those worked :)

I am running MariaDB using mariadb/server docker container, it runs on Ubuntu but I did not have any issues with apparmor

For me the problem was quit simple, I had the file in /root/data.csv and of course mysql user can't access it!

On the other hand, folks recommending LOAD DATA LOCAL INFILE as an alternative, while it works, but its performance is not as good as the standard "LOAD DATA INFILE" because when using "LOCAL" it assumes the file is being loaded from a remote terminal and its handling becomes different.

For best performance, use "LOAD DATA INFILE" always unless you have to load the file from a remote server or your laptop/desktop directly. This is of course disabled due to security reasons so you have to allow "LOCAL_INFILE" through your server's config file "/etc/my.cnf" or "/etc/my.cnf.d/server.cnf" depending on your OS.

Finally, for me the container had "secure_file_priv" parameter defined to "/data"

b510bf09bc5c [testdb]> SHOW GLOBAL VARIABLES LIKE '%SECURE_FILE_%';
| Variable_name    | Value  |
| secure_file_priv | /data/ |

This means, that the LOAD DATA INFILE will only work if the data file is being loaded from "/data" folder! Watch out for that and use the correct folder :)

Hope this helps someone.


How to determine whether an object has a given property in JavaScript

Underscore.js or Lodash

if (_.has(x, "y")) ...


Set custom attribute using JavaScript

Please use dataset

var article = document.querySelector('#electriccars'),
    data = article.dataset;

// data.columns -> "3"
// data.indexnumber -> "12314"
// data.parent -> "cars"

so in your case for setting data:

getElementById('item1').dataset.icon = "base2.gif";

Use of REPLACE in SQL Query for newline/ carriage return characters

There are probably embedded tabs (CHAR(9)) etc. as well. You can find out what other characters you need to replace (we have no idea what your goal is) with something like this:


SET @i = 1;

SELECT @var = AccountType FROM dbo.Account
  WHERE AccountNumber = 200
  AND AccountType LIKE '%Daily%';


WHILE @i <= LEN(@var)
  INSERT #x 
    SELECT SUBSTRING(@var, @i, 1), ASCII(SUBSTRING(@var, @i, 1));

  SET @i = @i + 1;


You might also consider doing better cleansing of this data before it gets into your database. Cleaning it every time you need to search or display is not the best approach.

How can I set the current working directory to the directory of the script in Bash?

I take this and it works.

cd "$(dirname "$0")"

Format LocalDateTime with Timezone in Java8"yyyyMMdd HH:mm:ss.SSSSSS Z"));

Define a struct inside a class in C++

Something like:

class Tree {

 struct node {
   int data;
   node *llink;
   node *rlink;

Set default value of an integer column SQLite

Use the SQLite keyword default


This link is useful:

Viewing localhost website from mobile device

To view localhost website from mobile device you have to follow thoses steps :

  • In your computer, you have to retrieve your IP address (Run > cmd > ipconfig)
  • If your localhost use a specific port (like localhost:12345 ), you have to open the port on your computer (Control Panel > System and Security > Firewall > Advanced settings and add Inbound rule)
  • Finally, you can access to your website from mobile device by navigate to : http://192.168.X.X:12345/

Hope it helps

PHP output showing little black diamonds with a question mark

Using the same charset (as suggested here) in both the database and the HTML has not worked for me... So remembering that the code is generated as HTML, I chose to use the &quot;(HTML code) or the &#34; (ISO Latin-1 code) in my database text where quotes were used. This solved the problem while providing me a quotation mark. It is odd to note that prior to this solution, only some of the quotation marks and apostrophes did not display correctly while others did, however, the special code did work in all instances.

Show animated GIF

For loading animated gifs stored in a source package (in the source code), this worked for me:

URL url = MyClass.class.getResource("/res/images/animated.gif");
ImageIcon imageIcon = new ImageIcon(url);
JLabel label = new JLabel(imageIcon);

How can I extract audio from video with ffmpeg?

Extract all audio tracks / streams

This puts all audio into one file:

ffmpeg -i -map 0:a -c copy
  • -map 0:a selects all audio streams only. Video and subtitles will be excluded.
  • -c copy enables stream copy mode. This copies the audio and does not re-encode it. Remove -c copy if you want the audio to be re-encoded.
  • Choose an output format that supports your audio format. See comparison of container formats.

Extract a specific audio track / stream

Example to extract audio stream #4:

ffmpeg -i input.mkv -map 0:a:3 -c copy output.m4a
  • -map 0:a:3 selects audio stream #4 only (ffmpeg starts counting from 0).
  • -c copy enables stream copy mode. This copies the audio and does not re-encode it. Remove -c copy if you want the audio to be re-encoded.
  • Choose an output format that supports your audio format. See comparison of container formats.

Extract and re-encode audio / change format

Similar to the examples above, but without -c copy. Various examples:

ffmpeg -i input.mp4 -map 0:a output.mp3
ffmpeg -i input.mkv -map 0:a output.m4a
ffmpeg -i input.avi -map 0:a -c:a aac output.mka
ffmpeg -i input.mp4 output.wav

Extract all audio streams individually

This input in this example has 4 audio streams. Each audio stream will be output as single, individual files.

ffmpeg -i -map 0:a:0 output0.wav -map 0:a:1 output1.wav -map 0:a:2 output2.wav -map 0:a:3 output3.wav

Optionally add -c copy before each output file name to enable stream copy mode.

Extract a certain channel

Use the channelsplit filter. Example to get the Front Right (FR) channel from a stereo input:

ffmpeg -i stereo.wav -filter_complex "[0:a]channelsplit=channel_layout=stereo:channels=FR[right]" -map "[right]" front_right.wav
  • channel_layout is the channel layout of the input. It is not automatically detected so you must provide the layout name.
  • channels lists the channel(s) you want to extract.
  • See ffmpeg -layouts for audio channel layout names (for channel_layout) and channel names (for channels).
  • Using stream copy mode (-c copy) is not possible to use when filtering, so the audio must be re-encoded.
  • See FFmpeg Wiki: Audio Channels for more examples.

What's the difference between -map and -vn?

ffmpeg has a default stream selection behavior that will select 1 stream per stream type (1 video, 1 audio, 1 subtitle, 1 data).

-vn is an old, legacy option. It excludes video from the default stream selection behavior. So audio, subtitles, and data are still automatically selected unless told not to with -an, -sn, or -dn.

-map is more complicated but more flexible and useful. -map disables the default stream selection behavior and ffmpeg will only include what you tell it to with -map option(s). -map can also be used to exclude certain streams or stream types. For example, -map 0 -map -0:v would include all streams except all video.

See FFmpeg Wiki: Map for more examples.


Invalid audio stream. Exactly one MP3 audio stream is required.

MP3 only supports 1 audio stream. The error means you are trying to put more than 1 audio stream into MP3. It can also mean you are trying to put non-MP3 audio into MP3.

WAVE files have exactly one stream

Similar to above.

Could not find tag for codec in stream #0, codec not currently supported in container

You are trying to put an audio format into an output that does not support it, such as PCM (WAV) into MP4.

Remove -c copy, choose a different output format (change the file name extension), or manually choose the encoder (such as -c:a aac).

See comparison of container formats.

Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument

This is a useless, generic error. The actual, informative error should immediately precede this generic error message.

How to print variables without spaces between values

print(*objects, sep=' ', end='\n', file=sys.stdout)

Note: This function is not normally available as a built-in since the name print is recognized as the print statement. To disable the statement and use the print() function, use this future statement at the top of your module:

from future import print_function

Unioning two tables with different number of columns

if only 1 row, you can use join

Select t1.Col1, t1.Col2, t1.Col3, t2.Col4, t2.Col5 from Table1 t1 join Table2 t2;

fatal: does not appear to be a git repository

It is most likely that you got your repo's SSH URL wrong.

To confirm, go to your repository on Github and click the clone or download button. Then click the use SSH link.

ssh link

Now copy your official repo's SSH link. Mine looked like this - [email protected]:borenho/que-ay.git

You can now do git remote add origin [email protected]:borenho/que-ay.git if you didn't have origin yet.

If you had set origin before, change it by using git remote set-url origin [email protected]:borenho/que-ay.git

Now push with git push -u origin master

How do I make text bold in HTML?

Could someone tell me what I'm doing wrong?"

"bold" has never been an HTML element ("b" is the closest match).

HTML should contain structured content; publisher CSS should suggest styles for that content. That way user agents can expose the structured content with useful styling and navigational controls to users who can't see your suggested bold styling (e.g. users of search engines, totally blind users using screen readers, poorly sighted users using their own colors and fonts, geeky users using text browsers, users of voice-controlled, speaking browsers like Opera for Windows). Thus the right way to make text bold depends on why you want to style it bold. For example:

  • Want to distinguish headings from other text? Use heading elements ("h1" to "h6") and suggest a bold style for them within your CSS ("h1, h2, h3, h4, h5, h6 {font-weight: bold;}".

  • Want to embolden labels for form fields? Use a "label" element, programmatically associate it with the the relevant "select", "input" or "textarea" element by giving it a "for" attribute matching an "id" attribute on the target, and suggest a bold style for it within your CSS ("label {font-weight: bold;"}).

  • Want to embolden a heading for a group of related fields in a form, such as a group of radio choices? Surround them with a "fieldset" element, give it a "legend" element, and suggest a bold style for it within your CSS ("legend {font-weight: bold;}").

  • Want to distinguish a table caption from the table it captions? Use a "caption" element and suggest a bold style for it within your CSS ("caption {font-weight: bold;}").

  • Want to distinguish table headings from table data cells? Use a "th" element and suggest a bold style for it within your CSS ("th {font-weight: bold;}").

  • Want to distinguish the title of a referenced film or album from surrounding text? Use a "cite" element with a class ("cite class="movie-title"), and suggest a bold style for it within your CSS (".movie-title {font-weight: bold;}").

  • Want to distinguish a defined keyword from the surrounding text defining or explaining it? Use a "dfn" element and suggest a bold style for it within your CSS ("dfn {font-weight: bold;}").

  • Want to distinguish some computer code from surrounding text? Use a "code" element and suggest a bold style for it within your CSS ("code {font-weight: bold;}").

  • Want to distinguish a variable name from surrounding text? Use a "var" element and suggest a bold style for it within your CSS ("var {font-weight: bold;}").

  • Want to indicate that some text has been added as an update? Use an "ins" element and suggest a bold style for it within your CSS ("ins {font-weight: bold;}").

  • Want to lightly stress some text ("I love kittens!")? Use an "em" element and suggest a bold style for it within your CSS (e.g. "em {font-weight: bold;}").

  • Want to heavily stress some text, perhaps for a warning ("Beware the dog!")? Use a "strong" element and suggest a bold style for it within your CSS (e.g. "strong {font-weight: bold;}").

… You get the idea (hopefully).

Can't find an HTML element with the right semantics to express /why/ you want to make this particular text bold? Wrap it in a generic "span" element, give it a meaningful class name that expresses your rationale for distinguishing that text ("<span class="lede">Let me begin this news article with a sentence that summarizes it.</span>), and suggest a bold style for it within your CSS (".lede {font-weight: bold;"}. Before making up your own class names, you might want to check if there's a microformat ( or common convention for what you want to express.

Reading Space separated input in python

You can do the following if you already know the number of fields of the input:

client_name = raw_input("Enter you first and last name: ")
first_name, last_name = client_name.split() 

and in case you want to iterate through the fields separated by spaces, you can do the following:

some_input = raw_input() # This input is the value separated by spaces
for field in some_input.split():
    print field # this print can be replaced with any operation you'd like
    #             to perform on the fields.

A more generic use of the "split()" function would be:

    result_list = some_string.split(DELIMITER)

where DELIMETER is replaced with the delimiter you'd like to use as your separator, with single quotes surrounding it.

An example would be:

    result_string = some_string.split('!')    

The code above takes a string and separates the fields using the '!' character as a delimiter.

Are Git forks actually Git clones?

Apart from the fact that cloning is from server to your machine and forking is making a copy on the server itself, an important difference is that when we clone, we actually get all the branches, labels, etc.

But when we fork, we actually only get the current files in the master branch, nothing other than that. This means we don't get the other branches, etc.

Hence if you have to merge something back to the original repository, it is a inter-repository merge and will definitely need higher privileges.

Fork is not a command in Git; it is just a concept which GitHub implements. Remember Git was designed to work in peer-to-peer environment without the need to synchronize stuff with any master copy. The server is just another peer, but we look at it as a master copy.

How to update and delete a cookie?

The cookie API is kind of lame. Let me clarify...

You don't update cookies; you overwrite them:

    document.cookie = "username=Arnold"; // Create 'username' cookie
    document.cookie = "username=Chuck"; // Update, i.e. overwrite, the 'username' cookie to "Chuck"

You also don't delete cookies; you expire them by setting the expires key to a time in the past (-1 works too).


Table header to stay fixed at the top when user scrolls it out of view with jQuery

I was able to fix the problem with changing column widths. I started with Andrew's solution above (thanks so much!) and then added one little loop to set the widths of the cloned td's:

$("#header-fixed td").each(function(index){
    var index2 = index;
        return $("#table-1 td").eq(index).width();

This solves the problem without having to clone the entire table and hide the body. I'm brand new to JavaScript and jQuery (and to stack overflow), so any comments are appreciated.

How to create a String with carriage returns?

It depends on what you mean by "multiple lines". Different operating systems use different line separators.

In Java, \r is always carriage return, and \n is line feed. On Unix, just \n is enough for a newline, whereas many programs on Windows require \r\n. You can get at the platform default newline use System.getProperty("line.separator") or use String.format("%n") as mentioned in other answers.

But really, you need to know whether you're trying to produce OS-specific newlines - for example, if this is text which is going to be transmitted as part of a specific protocol, then you should see what that protocol deems to be a newline. For example, RFC 2822 defines a line separator of \r\n and this should be used even if you're running on Unix. So it's all about context.

How to insert multiple rows from a single query using eloquent/fluent

It is really easy to do a bulk insert in Laravel with or without the query builder. You can use the following official approach.

    ['name' => 'Pierre Yem Mback', 'city' => 'Eseka', 'salary' => 10000000],
    ['name' => 'Dial rock 360', 'city' => 'Yaounde', 'salary' => 20000000],
    ['name' => 'Ndibou La Menace', 'city' => 'Dakar', 'salary' => 40000000]
], ['name', 'city'], ['salary']);

CSS Border Not Working

Have you tried using Firebug to inspect the rendered HTML, and to see exactly what css is being applied to the various elements? That should pick up css errors like the ones mentioned above, and you can see what styles are being inherited and from where - it is an invaluable too in any css debugging.

How to find the last day of the month from date?

There are ways to get last day of month.

//to get last day of current month
echo date("t", strtotime('now'));

//to get last day from specific date
$date = "2014-07-24";
echo date("t", strtotime($date));

//to get last day from specific date by calendar
$date = "2014-07-24";
echo cal_days_in_month(CAL_GREGORIAN, $dateArr[1], $dateArr[0]); 

How to load a model from an HDF5 file in Keras?

load_weights only sets the weights of your network. You still need to define its architecture before calling load_weights:

def create_model():
   model = Sequential()
   model.add(Dense(64, input_dim=14, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(64, init='uniform'))
   model.add(BatchNormalization(epsilon=1e-06, mode=0, momentum=0.9, weights=None))
   model.add(Dense(2, init='uniform'))
   return model

def train():
   model = create_model()
   sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
   model.compile(loss='binary_crossentropy', optimizer=sgd)

   checkpointer = ModelCheckpoint(filepath="/tmp/weights.hdf5", verbose=1, save_best_only=True), y_train, nb_epoch=20, batch_size=16, show_accuracy=True, validation_split=0.2, verbose=2, callbacks=[checkpointer])

def load_trained_model(weights_path):
   model = create_model()

What's "tools:context" in Android layout files?


tools: context = "activity name" it won't be packaged into the apk .Only ADT Layout Editor in your current Layout file set corresponding rendering context, show your current Layout in rendering the context is the activity name corresponds to the activity, if the activity in the manifest file set a Theme, then ADT Layout Editor will render your current Layout according to the Theme.Means that if you set the MainActivity set a Theme. The Light (the other), then you see in visual layout manager o background control of what should be the Theme. The Light looks like.Only to show you what you see is what you get results.

Some people see will understand some, some people see the also don't know, I'll add a few words of explanation:


Take a simple tools:text, for example, some more image, convenient to further understand the tools:context

    android:text="sample name1" />

    tools:text="sample name2" />

enter image description here

TextView1 adopted the android: text, and use the tools:text in the TextView2, on the right side of the Layout editor will display the sample name1, the sample name2 two font, if after you run the code to compile, generated apk, terminal display only the sample name1, does not show the sample name2 the words. You can try to run, see how the effect.

3.Specific description

1.The tools: context = "activity name" it won't be packaged into the apk(understanding: the equivalent of this is commented, the compiled no effect.)

2.Only ADT Layout Editor (i.e., for the above icon on the right side of the simulator) in the current Layout file set corresponding rendering context, the Layout of the current XML in rendering the context is the activity name corresponds to the activity, if the activity in the manifest file set a Theme, then ADT Layout Editor will render your current Layout according to the Theme.Means that if you set the MainActivity set a Theme. The Light can also be (other).(understand: you added tools: context = "activity name", the XML layout is rendering specified activity, establishes a Theme in the manifest file, pictured above right simulator Theme style will also follow changes corresponding to the Theme.)


To sum up, these properties mainly aimed at above the right tools, the simulator debugging time display status, and compile doesn't work,

Request header field Access-Control-Allow-Headers is not allowed by Access-Control-Allow-Headers

I had the same problem. In the jQuery documentation I found:

For cross-domain requests, setting the content type to anything other than application/x-www-form-urlencoded, multipart/form-data, or text/plain will trigger the browser to send a preflight OPTIONS request to the server.

So though the server allows cross origin request but does not allow Access-Control-Allow-Headers , it will throw errors. By default angular content type is application/json, which is trying to send a OPTION request. Try to overwrite angular default header or allow Access-Control-Allow-Headers in server end. Here is an angular sample:

$, data, {
    headers : {
        'Content-Type' : 'application/x-www-form-urlencoded; charset=UTF-8'

PHP: convert spaces in string into %20?

Use the rawurlencode function instead.

How do I return multiple values from a function in C?

Two different approaches:

  1. Pass in your return values by pointer, and modify them inside the function. You declare your function as void, but it's returning via the values passed in as pointers.
  2. Define a struct that aggregates your return values.

I think that #1 is a little more obvious about what's going on, although it can get tedious if you have too many return values. In that case, option #2 works fairly well, although there's some mental overhead involved in making specialized structs for this purpose.

How to copy part of an array to another array in C#?

int[] b = new int[3];
Array.Copy(a, 1, b, 0, 3);
  • a = source array
  • 1 = start index in source array
  • b = destination array
  • 0 = start index in destination array
  • 3 = elements to copy