php - 在php中查找子字符串的最有效方法

Question

在招聘流程技能测试中，我被问到以下问题:

Assuming a large random string, eg:

$x = str_shuffle(str_repeat(implode('', range('a', 'z')), 1000000));

What's the most efficient way to find substrings on it?

我想知道答案只是为了了解它。

先谢谢了!

Answer 1

你可以这样做:

<?php
$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.
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";
}