php下使用strpos需要注意 === 運算子

複製代碼 代碼如下:<?php
/*
判斷字串是否存在的函數
*/
function strexists($haystack, $needle) {
return !(strpos($haystack, $needle) === FALSE);//注意這裡的"==="
}
/*
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.
// 簡單的使用 "==" 號是不會起作用的，需要使用 "==="，因為 a 第一次出現的位置為 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
// 在搜尋字元的時候可以使用參數 offset 來指定位移量
$newstring　= 'abcdef abcdef';
$pos　= strpos($newstring, 'a', 1); // $pos = 7, not 0
?>