Procedure to create a constant variable in PHP
PHP Constants
v
PHP
constants are name or identifier that can't be changed during the execution of
the script except for magic constants, which are not really constants.
v
PHP
constants can be defined by 2 ways:
Ø
Using define() function
Ø
Using const keyword
v
Constants
are similar to the variable except once they defined, they can never be
undefined or changed.
v
They
remain constant across the entire program.
v
PHP
constants follow the same PHP variable rules.
v
For
example,
it can be started with a letter or underscore only.
Conventionally, PHP
constants should be defined in uppercase letters.
PHP
constant: define()
v
Use
the define() function to create a constant.
v
It
defines constant at run time.
v
Syntax
of define() function in PHP.
define(name, value, case-insensitive)
Ø name: It specifies the constant name.
Ø value: It specifies the constant
value.
Ø case-insensitive: Specifies whether a constant is
case-insensitive. Default value is false. It means it is case sensitive by
default.
Example to define PHP
constant using define().
File: constant1.php
<?php
define("MESSAGE","Hello JavaTpoint PHP");
echo MESSAGE;
?>
Output:
Hello JavaTpoint PHP
PHP
constant: const keyword
v
PHP
introduced a keyword const to
create a constant.
v
The
const keyword defines constants at compile time.
v
It
is a language construct, not a function.
v
The
constant defined using const keyword are case-sensitive.
File:
constant4.php
<?php
const MESSAGE="Hello const by JavaTpoint PHP";
echo MESSAGE;
?>
Output:
Hello const by JavaTpoint PHP
Constant()
function
There is another way to
print the value of constants using constant() function instead of using the
echo statement.
Syntax
The syntax for the
following constant function:
constant (name)
File:
constant5.php
<?php
define("MSG", "JavaTpoint");
echo MSG, "</br>";
echo constant("MSG");
//both are similar
?>
Output:
JavaTpointJavaTpoint
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