<?php
//字母 a k
$str1 = 'a';
$str2 = 'k';
$res = strcmp($str1,$str2);
echo $res;
echo "<br />";
//输出-1
$res = strcmp($str2,$str1);
echo $res;
echo "<br />";
//输出 1

//数字： 1 ,2 ,10, 12
$arr = array(10,1,2,19999999);
usort($arr,"strcmp");
print_r($arr);
echo "<br />";
//Array ( [0] => 1 [1] => 10 [2] => 19999999 [3] => 2 )


//字符串
$str_arr = array('1','1.1','1.1.1','1.1.1.1','2','2.1','2.1.1','2.2');
usort($str_arr,"strcmp");
print_r($str_arr);
echo "<br />";
//Array ( [0] => 1 [1] => 1.1 [2] => 1.1.1 [3] => 1.1.1.1 [4] => 2 [5] => 2.1 [6] => 2.1.1 [7] => 2.2 )

//中文是怎么排序的呢，仔细想想，在新华字典中的排序，是按照拼音的，
//比如，a ai an ang  ao
//ba  bai  ban   bang

//那么我们就比较这些值吧，看一下
$str_cn = array('吧','啊','白','奥','昂','爱','安','般','帮');
usort($str_cn,"strcmp");
print_r($str_cn);
echo "<br />";
//Array ( [0] => 吧 [1] => 啊 [2] => 奥 [3] => 安 [4] => 帮 [5] => 昂 [6] => 爱 [7] => 白 [8] => 般 )