";$rest = substr($str, 1, 3); // 返回 "bcd"echo $rest . "
";$rest = substr($str, -3); // 返回 "lmn"echo $rest . "
";$rest = substr($str, -3, 2); // 返回 "lm"echo $rest . "
";$rest = substr($str, 1, -3); // 返回 "bcdefghijk"echo $rest . "
";$rest = substr($str, -7, -3); // 返回 "hijk"echo $rest . "
";?>
