问匹配特定长度的数字和字母组成的字符串

EN

^(?=.*\d)(?=.*[a-zA-Z])[a-zA-Z\d]{6,8}$

^              //The Start of the string
(?=.*\d)       //(?= ) is a look around. Meaning it
               //checks that the case is matched, but
               //doesn't capture anything
               //In this case, it's looking for any
               //chars followed by a digit.
(?=.*[a-zA-Z]) //any chars followed by a char.
[a-zA-Z\d]{6,8}//6-8 digits or chars.
$              //The end of the string.