[PHP] empty()、is_null()、isset() 區別
http://php.net/manual/en/types.comparisons.php http://www.blueshoes.org/en/developer/php_cheat_sheet/ (此圖的出處) http://overapi.com/php/ (列表) Empty() is_null() isSet() gettype() empty() is_null() isSet() (bool) $x = ""; string true false true false $x = null; NULL true true false false var $x; (not set) NULL true true false false $x = array(); array true false true false $x = false; boolean true false true false $x = 15; integer false false true true $x = 1; integer false false true true $x = 0; integer true false true false $x = -1; integer false false true true $x = "15"; string false false true true $x = "1"; string false false true true $x = "0"; string true false true false $x = "-1"; string false false true true $x = "foo"; string false false true true $x = "true"; string false false true true $x = "false"; string false false true true Note: empty() and isSet() don't give
