Example
Although not necessary in PHP however it is a very good practice to initialize variables. Uninitialized variables have a default value of their type depending on the context in which they are used:
Unset AND unreferenced
var_dump($unset_var); // outputs NULL
Boolean
echo($unset_bool ? "true\n" : "false\n"); // outputs 'false'
String
$unset_str .= 'abc';
var_dump($unset_str); // outputs 'string(3) "abc"'
Integer
$unset_int += 25; // 0 + 25 => 25
var_dump($unset_int); // outputs 'int(25)'
Float/double
$unset_float += 1.25;
var_dump($unset_float); // outputs 'float(1.25)'
Array
$unset_arr[3] = "def";
var_dump($unset_arr); // outputs array(1) { [3]=> string(3) "def" }
Object
$unset_obj->foo = 'bar';
var_dump($unset_obj); // Outputs: object(stdClass)#1 (1) { ["foo"]=> string(3) "bar" }
Relying on the default value of an uninitialized variable is problematic in the case of including one file into another which uses the same variable name.
