PHP
5 Constants
Constants
are like variables except that once they are defined they cannot be changed or
undefined.
PHP
Constants
A constant
is an identifier (name) for a simple value. The value cannot be changed during
the script.
A valid
constant name starts with a letter or underscore (no $ sign before the constant
name).
Note: Unlike
variables, constants are automatically global across the entire script.
Create a PHP
Constant
To create a
constant, use the define() function.
Syntax
define(name,
value, case-insensitive)
Parameters:
name:
Specifies the name of the constant
value:
Specifies the value of the constant
case-insensitive:
Specifies whether the constant name should be case-insensitive. Default is
false
The example
below creates a constant with a case-sensitive name:
Example
<?php
define("GREETING",
"Welcome to Omega.com!");
echo
GREETING;
?>
The example
below creates a constant with a case-insensitive name:
Example
<?php
define("GREETING",
"Welcome to Omega.com!", true);
echo
greeting;
?>
Constants
are Global
Constants
are automatically global and can be used across the entire script.
The example
below uses a constant inside a function, even if it is defined outside the
function:
Example
<?php
define("GREETING",
"Welcome to Omega.com!");
function
myTest() {
echo GREETING;
}
myTest();
?>
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