strpos php通过strpos查找字符串出现位置

<?php
echo strpos("Hello world!","wo");
?>

                                结出结果:6

                                由于strpos有两种类型的返回值，所以在判断是否找到子字符串的的时候最好使用===三个等号进行严格类型的相等比较

<?php
$haystack = "needle23423432";
$pos = strpos($haystack, "needle");
if ($pos==false) {
  print("Not found based (==) test\n");
} else {
  print("Found based (==) test\n");
}
if ($pos===false) {
  print("Not found based (===) test\n");
} else {
  print("Found based (===) test\n");
}
?>

                                上面的代码返回如下结果

This script will print:

Not found based (==) test
Found based (===) test

The (===) test is correct.