define

Defines a named constant

Syntax

define(string $constant_name, mixed $value): bool

Parameters

constant_name

The name of the constant.

Note: It is possible to define() constants with reserved or even invalid names, whose value can (only) be retrieved with constant(). However, doing so is not recommended.

value

The value of the constant.

Warning: While it is possible to define resource constants, it is not recommended and may cause unpredictable behavior.

Return

Returns TRUE on success or FALSE on failure.

Examples

1 · constant_name value · null

<?

define("MYCONSTANT", null);

var_export(MYCONSTANT);

?>
NULL

2 · constant_name value · boolean

<?

define("MYCONSTANT", true);

var_export(MYCONSTANT);

?>
true

3 · constant_name value · float

<?

define("MYCONSTANT", 0.1);

echo MYCONSTANT;

?>
0.1

4 · constant_name value · integer

<?

define("MYCONSTANT", 1);

echo MYCONSTANT;

?>
1

5 · constant_name value · string

<?

define("MYCONSTANT", "Hello World!");

echo MYCONSTANT;

?>
Hello World!

6 · constant_name value · array

<?

define("MYCONSTANT", array(0, 1));

print_r(MYCONSTANT);

?>
Array
(
    [0] => 0
    [1] => 1
)

7 · Return

<?

$return = define("MYCONSTANT", array(0, 1));

var_export($return);

?>
true

__halt_compiler

connection_aborted

connection_status

constant

defined

die

eval

exit

highlight_file

highlight_string

hrtime

ignore_user_abort

pack

php_strip_whitespace

show_source

sleep

sys_getloadavg

time_nanosleep

time_sleep_until

uniqid

unpack

usleep

PHP

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