c# 手机号分割

1、把手机号中间4为隐藏

        public  string ReturnPhoneNO(string phoneNo)
        {
            Regex re = new Regex("(\d{3})(\d{4})(\d{4})", RegexOptions.None);
            phoneNo = re.Replace(phoneNo, "$1****$3");
            return phoneNo;
        }        
       //例:    ReturnPhoneNO(131000084840); 输出：131****84840

2、手机号间隔显示

        public  string ReturnPhoneNO(string phoneNo)
        {
            Regex re = new Regex("(\d{3})(\d{4})(\d{4})", RegexOptions.None);
            phoneNo = re.Replace(phoneNo, "$1 $2 $3");
            return phoneNo;
        }        
       //例:    ReturnPhoneNO(131000084840); 输出：131 0000 84840