<?php

header("content-type:text/html;charset=utf-8");

$num = "i want to fly,Fly in the sky ,fly to the Higher!";

echo "全部转换为大写（strtoupper函数）",strtoupper($num),"<br/>","<br/>";

echo "全部转换为小写（strtolower函数）",strtolower($num),"<br/>","<br/>";

echo "整句的首字母大写",ucfirst($num),"<br/>","<br/>";

echo "每个单词首字母大写",ucwords($num),"<br/>","<br/>";