PHP Constant

·   A constant is an identifier or a name.These constant value remains the same during the execution of script.

·  Constant are like variable except  once the value is assigned to the constant it remains the same throughout the script.

·   Constant are case sensitive.

·    Note:Unlike Variable constant are global across the entire script.

·     Unlike variable you do not need to define $ sign before the name of a constant.

·     A constant name starts with underscore or letter,followed by number letter or underscore.when you have defined the constant ,it can never be changed.

Following is an example:

To create a php constant use define() function:

Syntax: define(name,value,case-sensitive);

 name:name of the constant.

 Value:value of the constant.

 Case-sensitive:specifies whether it should be case-sensitive or not.By default it is false.

<?php
define("text", "Hello World!!",true);
echo text;
?>

<?php
define("text", "Hello World!!",true);
function myPhp() {
    echo text;
}
myPhp();

?>

<?php
$text=”Hello”;
echo(“$text World!”);
?>