php判断0,null,false,''类似这些值时候必须用全等

<?php/** * Created by PhpStorm. * User: Administrator * Date: 16-1-9 * Time: 上午 */if ('' == 0) {    echo "''==0", '<hr>';}if ('' == false) {    echo "''==false", '<hr>';}if (0 == false) {    echo "0==false", '<hr>';}if (null == false) {    echo "null==false", '<hr>';}if (null == 0) {    echo "null==0", '<hr>';}if (null == '') {    echo "null==''", '<hr>';}

---------------------结果

''==0

---

''==false

---

0==false

---

null==false

---

null==0

---

null==''