php下使用strpos需要注意 ===全等 运算符

<?php
/*
判断字符串是否存在的函数
*/
function strexists($haystack, $needle) {
return !(strpos($haystack, $needle) === FALSE);//注意这里的\"===\"
}
/*
Test
*/
$mystring = \'abc\';
$findme = \'a\';
$pos = strpos($mystring, $findme);

// Note our use of ===. Simply == would not work as expected
// because the position of \'a\' was the 0th (first) character.
// 简单的使用 \"==\" 号是不会起作用的，需要使用 \"===\"，因为 a 第一次出现的位置为 0
if ($pos === false) {
echo \"The string \'$findme\' was not found in the string \'$mystring\'\";
} else {
echo \"The string \'$findme\' was found in the string \'$mystring\'\";
echo \" and exists at position $pos\";
}

// We can search for the character, ignoring anything before the offset
// 在搜索字符的时候可以使用参数 offset 来指定偏移量
$newstring　= \'abcdef abcdef\';
$pos　= strpos($newstring, \'a\', 1); // $pos = 7, not 0
?>