c# 字符串加掩码，隐藏部分字符串

执行结果

----------------- 字符串加掩码 -----------------
123*****89

执行代码

Console.WriteLine("----------------- 字符串加掩码 -----------------"); 
string str = "123456789"; 
Console.WriteLine(StringMask(str,3,2));

Console.Read();

工具代码 

/// <summary>
/// 字符串加掩码,字符串第一位的下标是0
/// </summary>
/// <param name="ValueString">值</param> 
/// <param name="StartReserve">起始保留字节数</param> 
/// <param name="EndReserve">尾部保留字节数</param>
/// <returns></returns>
public static string StringMask(string ValueString, int StartReserve, int EndReserve = 0)
{
    if (!string.IsNullOrEmpty(ValueString))
    {
        int len = ValueString.Length; 

        if (EndReserve >= len)
            EndReserve = 3;
        if (EndReserve < 0|| len<0)
            EndReserve = 0; 

        return ValueString.Substring(0, StartReserve) + "*****" + ValueString.Substring(len - EndReserve);

    } 
    return string.Empty;
}