I want to use an array as a constant in PHP 5.6. The question is: how to check whether a key 'a' exists in the array and get the "Test2" return true as well?
My code now is like this:
const ARR = array(
'a' => 'first',
'b' => 'second'
);
$test1 = defined("ARR");
$test2 = defined("ARR['a']");
echo '<br>Test1: ';
var_dump($test1);
echo '<br>Test2: ';
var_dump($test2);
Result:
Test1: bool(true)
Test2: bool(false)
You need to use array_key_exists function
var_dump(array_key_exists('a', ARR));
defined() checks if constant is defined and it is, so you can additionaly check if constant is array with is_array(ARR);
Example:
<?php
const ARR = array(
'a' => 'first',
'b' => 'second'
);
$test1 = array_key_exists('a', ARR);
$test2 = array_key_exists('c', ARR);
echo 'Test1: ';
var_dump($test1);
echo 'Test2: ';
var_dump($test2);
Output:
Test1: bool(true)
Test2: bool(false)
Notice:
It will work only with PHP version >= 5.6 Working fiddle
In php7+ you can use null coalescing:
if(self::ARR['a']??false){
}
$test2 = isset(ARR['a']);(PHP7)