小编use*_*949的帖子

我正在尝试在正则表达式语言 DART 中传递变量

  `betweenLenth(val, field, [min = 4, max = 20]) {
     final RegExp nameExp = new RegExp(r'^\w{" + min + "," + max + "}$');
     if (!nameExp.hasMatch(val))
     return field + " must be between $min - $max characters ";
   }`

谢谢