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  Handle ”cannot modify header information – headers already sent by”

Man PHP developers should encounter ”Warning: Cannot modify header information – headers already sent by ….” error before when executing a PHP script. Here are some solutions to this error. 1. Blank line Check whether there is any blank line after , especially in the files which are used in include() and require(0, some problems are caused by blank lines. 2. Add exit() after head() header (“Location: xxx”); exit(); 3. Use output cache <?php ob_start(); ...

   header sent, PHP error handle     2012-11-17 08:45:22

  do {...} while (0) in macros

If you are a C programmer, you must be familiar with macros. They are powerful and can help you ease your work if used correctly. However, if you don't define macros carefully, they may bite you and drive you crazy. In many C programs, you may see a special macro definition which may seem not so straightforward. Here is one example: #define __set_task_state(tsk, state_value) \ do { (tsk)->state = (state_value); } while (0) There are many this kind of macros which uses do{...}while(0)...

   C,macro,C++     2014-01-23 07:16:13

  jsonSerialize() in extended class

Since PHP 5.4.0, there is a convenient interface JsonSerializable which can be used to indicate that a PHP object can be serialized to JSON object. It has only one method which should be implemented by any class which implements this interface. The method is named jsonSerialize(). It's really easy to serialize an object to JSON object. Here is one example: <?php class ArrayValue implements JsonSerializable { public function __construct(array $array) { $this->array = $array; ...

   JSON,jsonSerialize,Inheritance,extends     2014-07-26 05:54:00

  Build route graph of Hurricane Sandy

Hurricane Sandy swept US east side and landed in New York, it killed 113 persons and incurred 50 billion US dollars economic loss. Sandy is also considered as the most expensive hurricane. We will now use matplotlib and basemap libraries in Python to build a route graph of Sandy. Below is the animated GIF. Shadow is added in the graph to show the time at night, we can see from the graph that Sandy stayed a while in Panama after emerging, then it went through Cuba and became Hurricane-2. Late...

   Hurricane Sandy,Route graph,Python     2012-11-17 07:58:13

  jQuery to check whether checkbox is checked

In Vanilla JavaScript, the correct way of checking whether a checkbox is checked is to get the property checked of the checkbox. Assuming there is an checkbox with id "checkbox1", below line will return true if the checkbox is checked while it will return false if the checkbox is unchecked: document.getElementById("checkbox1").checked In jQuery, there are a few ways to check this. The first one is to using the corresponding counterpart of the Vanilla JavaScript, it is to check the checked proper...

   jQuery,checked,checkbox,attr,prop     2015-07-25 08:49:54

  var in JavaScript

Geoff published an article sometime ago--"How one missing var ruined our launch". This article described one case where MelonCard uses Node.js as their backend system, suddenly there was a small registration peak period--50-100 people registered concurrently, then the entire website stopped responding and many other strange problems showed up. When they were investigating the source of the problem, they found one missing var in the following code.app.all(‘/apps/:user_id/status’, fun...

   JavaScript,Scope,variable     2012-05-26 12:35:36

  The tic-tac-toe game with Python

In this tutorial, we will show how to build a tic-tac-toe game with Python. We will use functions,arrays,if statements,while statements, for loops and error handling etc. First, we need to create two functions, the first function will display the borad of the game: def print_board(): for i in range(0,3): for j in range(0,3): print map[2-i][j], if j != 2: print "|", print "" Here we used two for loops to loop through the map, this map is...

   Python,Tic-Tac-Toe     2013-07-30 02:49:09

  A trap in PDOStatement::bindParam

First, let's check out below codes: <?php $dbh = new PDO('mysql:host=localhost;dbname=test', "test"); $query = <<prepare($query); $bind_params = array(':username' => "laruence", ':password' => "weibo"); foreach( $bind_params as $key => $value ){ $statement->bindParam($key, $value); } $statement->execute(); What is the SQL executed finally? Is there any problem with above codes? Many people may think the query executed is : INSERT INTO `user` (`username`, `password...

   PHP,Trap,bindParam     2013-08-29 10:48:55

  Top 10 Tell Tale Signs Your Computer Has a Virus

The true genius of the 'computer' is its ability to make human lives easier. This is only achieved from the ability of running software such as word processing, number crunching with Excel or learning from the worlds largest source of knowledge, via web browsers. Today being connected to the internet is fundamental to leading a productive modern life. While internet is a boon it comes with its own share of problems. As internet users increase so does the instance of com...

   COMPUTER VIRUS, INTERNET SECURITY, DATA SECURITY, ANTIVIRUS, COMPUTER REPAIR     2017-03-19 21:05:12

  HTML5 Web Worker

Web Worker is a JavaScript multithreading solution provided by HTML5. we can put some compute intensive codes into Web Worker and it will not hang the user interface. 1. How to use Web Worker Web Worker's basic mechanism is to use Worker to load a JavaScript file to create a new thread in JavaScript's main thread. It will not block other thread's execution and will provide a data exchange interface between main thread and new thread : postMessage() and onmessage. Let's look at an example: //work...

   JavaScript,HTML,Web Worker     2012-12-02 06:25:00

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