php字符串学习之substr()

";$rest = substr($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 . "
";?>