C# 用 *? 屏蔽掉字符串的前 12 个字符。
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Mask out part first 12 characters of string with *?
提问by Xaisoft
How can I take the value 123456789012345or 1234567890123456and turn it into:
我如何获取价值123456789012345或1234567890123456将其转换为：
************2345and ************3456
************2345和 ************3456
The difference between the strings above is that one contains 15 digits and the other contains 16.
上述字符串的区别在于，一个包含 15 个数字，另一个包含 16 个。
I have tried the following, but it does not keep the last 4 digits of the 15 digit number and now matter what the length of the string, be it 13, 14, 15, or 16, I want to mask all beginning digits with a *, but keep the last 4. Here is what I have tried:
我尝试了以下方法，但它没有保留 15 位数字的最后 4 位数字，现在不管字符串的长度是 13、14、15 还是 16，我想用*，但保留最后 4 个。这是我尝试过的：
String.Format("{0}{1}", "************", str.Substring(11, str.Length - 12))
采纳答案by Darin Dimitrov
using System;
class Program
{
static void Main()
{
var str = "1234567890123456";
if (str.Length > 4)
{
Console.WriteLine(
string.Concat(
"".PadLeft(12, '*'),
str.Substring(str.Length - 4)
)
);
}
else
{
Console.WriteLine(str);
}
}
}
回答by John Feminella
Try this:
尝试这个：
var maskSize = ccDigits.Length - 4;
var mask = new string('*', maskSize) + ccDigits.Substring(maskSize);
回答by sll
LINQ:
林克：
char maskBy = '*';
string input = "123456789012345";
int count = input.Length <= 4 ? 0 : input.Length - 4;
string output = new string(input.Select((c, i) => i < count ? maskBy : c).ToArray());
回答by Mike Hofer
Easiest way: Create an extension method to extract the last four digits. Use that in your String.Format call.
最简单的方法：创建一个扩展方法来提取最后四位数字。在您的 String.Format 调用中使用它。
For example:
例如：
public static string LastFour(this string value)
{
if (string.IsNullOrEmpty(value) || value.length < 4)
{
return "0000";
}
return value.Substring(value.Length - 4, 4)
}
In your code:
在您的代码中：
String.Format("{0}{1}", "************", str.LastFour());
In my opinion, this leads to more readable code, and it's reusable.
在我看来，这会导致代码更具可读性，并且是可重用的。
EDIT:Perhaps not the easiest way, but an alternative way that may produce more maintainable results. <shrug/>
编辑：也许不是最简单的方法，而是一种可能产生更易于维护的结果的替代方法。<耸肩/>
回答by Daniel Pe?alba
Try the following:
请尝试以下操作：
private string MaskString(string s)
{
int NUM_ASTERISKS = 4;
if (s.Length < NUM_ASTERISKS) return s;
int asterisks = s.Length - NUM_ASTERISKS;
string result = new string('*', asterisks);
result += s.Substring(s.Length - NUM_ASTERISKS);
return result;
}
回答by Bob Vale
Regex with a match evaluator will do the job
带有匹配评估器的正则表达式将完成这项工作
string filterCC(string source) {
var x=new Regex(@"^\d+(?=\d{4}$)");
return x.Replace(source,match => new String('*',match.Value.Length));
}
This will match any number of digits followed by 4 digits and the end (it won't include the 4 digits in the replace). The replace function will replace the match with a string of * of equal length.
这将匹配任意数量的数字，后跟 4 位数字和结尾（它不会在替换中包含 4 位数字）。替换函数将用等长的 * 字符串替换匹配项。
This has the additional benefit that you could use it as a validation algorthim too. Change the first + to {11,12} to make it match a total of 15 or 16 chars and then you can use x.IsMatchto determine validity.
这还有一个额外的好处，您也可以将其用作验证算法。将第一个 + 更改为 {11,12} 以使其匹配总共 15 或 16 个字符，然后您可以使用它x.IsMatch来确定有效性。
EDIT
编辑
Alternatively if you always want a 16 char result just use
或者，如果您总是想要 16 个字符的结果，请使用
return x.Replace(source,new String('*',12));
回答by anjunatl
static private String MaskInput(String input, int charactersToShowAtEnd)
{
if (input.Length < charactersToShowAtEnd)
{
charactersToShowAtEnd = input.Length;
}
String endCharacters = input.Substring(input.Length - charactersToShowAtEnd);
return String.Format(
"{0}{1}",
"".PadLeft(input.Length - charactersToShowAtEnd, '*'),
endCharacters
);
}
Adjust the function header as required, call with:
根据需要调整函数头，调用：
MaskInput("yourInputHere", 4);
回答by Fabio Luz
A simple way
一个简单的方法
string s = "1234567890123"; // example
int l = s.Length;
s = s.Substring(l - 4);
string r = new string('*', l);
r = r + s;
回答by Mark Mintoff
Try this out:
试试这个：
static string Mask(string str)
{
if (str.Length <= 4) return str;
Regex rgx = new Regex(@"(.*?)(\d{4})$");
string result = String.Empty;
if (rgx.IsMatch(str))
{
for (int i = 0; i < rgx.Matches(str)[0].Groups[1].Length; i++)
result += "*";
result += rgx.Matches(str)[0].Groups[2];
return result;
}
return str;
}
回答by Chris Dunaway
Something like this:
像这样的东西：
string s = "1234567890123"; // example
string result = s.Substring(s.Length - 4).PadLeft(s.Length, '*');
This will mask all but the last four characters of the string. It assumes that the source string is at least 4 characters long.
这将屏蔽除字符串的最后四个字符之外的所有字符。它假定源字符串至少有 4 个字符长。
