Default values of uninitialized variables on PHP |

<?php

// Unset AND unreferenced (no use context) variable; outputs NULL

var_dump($unset_var);
// Boolean usage; outputs 'false' (See ternary operators for more on this syntax)

echo($unset_bool ? "true\n" : "false\n");
// String usage; outputs 'string(3) "abc"'

$unset_str .= 'abc';

var_dump($unset_str);
// Integer usage; outputs 'int(25)'

$unset_int += 25; // 0 + 25 => 25

var_dump($unset_int);
// Float/double usage; outputs 'float(1.25)'

$unset_float += 1.25;

var_dump($unset_float);
// Array usage; outputs array(1) {  [3]=>  string(3) "def" }

$unset_arr[3] = "def"; // array() + array(3 => "def") => array(3 => "def")

var_dump($unset_arr);

// Object usage; creates new stdClass object (see http://www.php.net/manual/en/reserved.classes.php) // Outputs: object(stdClass)#1 (1) { ["foo"]=> string(3) "bar" } $unset_obj->foo = 'bar'; var_dump($unset_obj); ?>