DEFINE vs Variable in PHP
PhpPhp Problem Overview
Can someone explain the difference between using
define('SOMETHING', true);
and
$SOMETHING = true;
And maybe the benefits between one or the other?
I use variables everywhere and even in a config type file that is included to everypage I still use variables as I don't see why to use the define method.
Php Solutions
Solution 1 - Php
DEFINE makes a constant, and constants are global and can be used anywhere. They also cannot be redefined, which variables can be.
I normally use DEFINE for Configs because no one can mess with it after the fact, and I can check it anywhere without global-ling, making for easier checks.
Solution 2 - Php
Once defined, a 'constant' cannot be changed at runtime, whereas an ordinary variable assignment can.
Constants are better for things like configuration directives which should not be changed during execution. Furthermore, code is easier to read (and maintain & handover) if values which are meant to be constant are explicitly made so.
Solution 3 - Php
There is also a difference in scope.
In the example given by the orignal poster, $SOMETHING will not be accessible within a function whereas define('SOMETHING', true) will be.
Solution 4 - Php
define() makes a read-only variable, compared to a standard variable that supports read and write operations.
Solution 5 - Php
A constant is very useful when you want access data from inside a function, check this
<?php
function data(){
define("app","hey you can see me from outside the function",false);
$tech = "xampp";
}
data();
echo $tech;
echo app;
?>
If you use a variable you are never going to get the inside value here is what i get
Notice: Undefined variable: tech in D:\xampp\htdocs\data\index.php on line 8 hey you can see me from outside the function