SHA1 PHP encryption function

SHA1 accept a string as a key and return hash string which is encrypted. For decryption key is required, which is used in the encryption.

Syntax

string sha1 ( string $str [, bool $raw_output = false ] )

If the optional raw_output is set to TRUE, then the sha1 digest is instead returned in raw binary format with a length of 20, otherwise the returned value is a 40-character hexadecimal number.

Preemption in OS

In computing, preemption is the act of temporarily interrupting a task being carried out by a computer system, without requiring its cooperation, and with the intention of resuming the task at a later time. Such a change is known as a context switch. It is normally carried out by a privileged task or part of the system known as a preemptive scheduler, which has the power to preempt, or interrupt, and later resume, other tasks in the system.

Tags - Display HTML code in HTML

There are many times when we want to show HTML tags on our web page mainly when we make some HTML tutorial type application. This enables you to show an HTML code example on your webpage. Following code help you


<xmp>
<h1>Test </h1>
</xmp>

&lt marquee &gt

PHP Variable Scope

Local Variable

     A local variable is accessible only the block where it has defined. When a code block over then the entire local variable inside of block automatically released by the compiler.

<?php

           

            function fun1()

            {                      

                        $a=10;

                        echo $a;

            }

            function fun2()

            {

                        echo $a+10;

                        // Error : Undefined variable: a because it has not defined in fun2 and a is local variable for  fun1

            }          

?>

<?php

            //fun1();

            fun2();

?>

Global Variable

     The scope of a PHP variable depends on where it has defined I.e. when a variable is declared in top side of the PHP code block, then it becomes global variable for all PHP code block but not inside of a function.