屏蔽除字符串的前6位和后4位之外的所有数字（长度变化） [英] mask all digits except first 6 and last 4 digits of a string( length varies )

问题描述

我有一个卡号作为字符串，例如：

I have a card number as a string, for example:

string  ClsCommon.str_CardNumbe r = "3456123434561234";

此卡号的长度可以从16到19位数字不等，具体取决于要求。

The length of this card number can vary from 16 to 19 digits, depending on the requirement.

我的要求是，我必须显示卡号的前六位数字和后四位数字，并用'X'掩盖中间的其他字符。

My requirement is that I have to show the first six digits and the last 4 digits of a card number and mask the other characters in between with the character 'X'.

我尝试使用subString并将其分别实现为16、17、18、19位数字。

I have tried using subString and implemented it separately for 16,17,18,19 digits..

我拆分了字符串（ClsCommon.str_CardNumber）到5个字符串（str_cardNum1，str_cardNum2，str_cardNum3，str_cardNum4，str_cardNum5-每个字符串4个数字。.第5个字符串的剩余数字）

I split string(ClsCommon.str_CardNumber) to 5 strings (str_cardNum1, str_cardNum2, str_cardNum3, str_cardNum4, str_cardNum5 - 4 digits for each string..remaining digits for 5th string)

所有字符串放置在ClsCommon文件中。
基于此，我实现了下面的方法，该方法非常有效：

All the strings are placed in ClsCommon file. Based on that I implemented the below, which works perfectly:

if (ClsCommon.str_CardNumber.Length == 16) {
    txtmskcrdnum.Text = string.Concat(ClsCommon.str_cardNum1, " ", ClsCommon.str_cardNum2.Substring(0, 2), "XX", " ", "XXXX", " ", ClsCommon.str_cardNum4);

}
if (ClsCommon.str_CardNumber.Length == 17) {
    txtmskcrdnum.Text = string.Concat(ClsCommon.str_cardNum1, " ", ClsCommon.str_cardNum2.Substring(0, 2), "XX", " ", "XXXX", " ", "X", ClsCommon.str_cardNum4.Substring(1, 3), " ", ClsCommon.str_cardNum5);
}
if (ClsCommon.str_CardNumber.Length == 18) {
    txtmskcrdnum.Text = string.Concat(ClsCommon.str_cardNum1, " ", ClsCommon.str_cardNum2.Substring(0, 2), "XX", " ", "XXXX", " ", "XX", ClsCommon.str_cardNum4.Substring(2, 2), " ", ClsCommon.str_cardNum5);
}


if (ClsCommon.str_CardNumber.Length == 19) {
    txtmskcrdnum.Text = string.Concat(ClsCommon.str_cardNum1, " ", ClsCommon.str_cardNum2.Substring(0, 2), "XX", " ", "XXXX", " ", "XXX", ClsCommon.str_cardNum4.Substring(3, 1), " ", ClsCommon.str_cardNum5);
}
txtmskcrdnum.Text = ClsCommon.str_CardNumber.PadLeft(ClsCommon.str_CardNumber.Length, 'X').Substring(ClsCommon.str_CardNumber.Length - 4);

对于多个长度，上述方法没有用。

For multiple lengths, the above approach is not useful.

我想要一种显示前6位和后4位并用X掩盖其他数字的方法。
最后一个字符串应在每4位之间留一个空格。

I want a single approach which displays the first 6 and last 4 digits and masks other digits with X. The final string should have a space between every 4 digits.

推荐答案

这将适用于任何卡号长度：

This will work with any card number length:

var cardNumber = "3456123434561234";

var firstDigits = cardNumber.Substring(0, 6);
var lastDigits = cardNumber.Substring(cardNumber.Length - 4, 4);

var requiredMask = new String('X', cardNumber.Length - firstDigits.Length - lastDigits.Length);

var maskedString = string.Concat(firstDigits, requiredMask, lastDigits);
var maskedCardNumberWithSpaces = Regex.Replace(maskedString, ".{4}", "$0 ");

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