<!DOCTYPE html>
<html>
<body>
<?php
echo strcasecmp("Hello world!","HELLO WORLD!")."<br>"; // 两字符串相等
echo strcasecmp("Hello world!","HELLO")."<br>"; // string1 大于 string2
echo strcasecmp("Hello world!","HELLO WORLD! HELLO!")."<br>"; // string1 小于 string2
?>
</body>
</html>