PHP 访问单个字符

• 函数strlen()返回字符串中的字符数，即字符长度：

$string = 'Hello, world';
$length = strlen($string);	//$length为12

• 可以在字符串中使用字符串偏移量语法来定位单个字符：

$string = 'Hello';
for($i = 0;$i < strlen($string);$i++){
    print("The %dth character is %s\n",$i,$string{$i});
}

The 0th character is H
The 1th character is e
The 2th character is l
The 3th character is l
The 4th character is o