PHP中字符串大小寫切換以及翻轉和加密 //將小寫字母全部變成大寫字母 $a = 'hello world'; echo strtoupper($a);//HELLO WORLD! //將大寫字母全部變成小寫字母 $b = 'HELLO WORLD!'; echo strtolower($b);//hello world! //將語句中的首字母變成大寫 $c = 'my name is fxxy'; echo ucfirst($c);//My name is fxxy //將語句中每個字母的首字母變成大寫 $d = 'my name is fxxy'; echo ucwords($d);//My Name Is Fxxy; //字符串翻轉函數 $e = 'hello world'; echo strrev($a);//!dlrow olleh //字符串加密函數 $f = 'hello fxxy'; echo md5($f); //b9facffba44a838e493d2f8f28bb3584