手机号中间四位替换

方法一 ：根据未知替换

　　String subStr = phone.Substring(3, 4);
　　oldcellphone.Text = phone.Replace(subStr, "****");

方法二：正则表达式，

 

　　Regex re = new Regex("(\\d{3})(\\d{4})(\\d{4})", RegexOptions.None);
　　var test= re.Replace("12345678901", "$1****$3");