how to do masking/hiding email address in c#

Question

i have an issue, i have to apply masking/hiding part of email address in c#. example

[email protected]==> jh**[email protected]
[email protected]==> bi****[email protected]
[email protected]==>br*******[email protected]

i have this code but its giving exception for some emails. "Index was outside the bounds of the array."

for (int i = 0; i < eml.Length; i++)
{
 int j = i == (eml.Length - 1) ? 0 : 1;
 cc = eml[i].ToString();
 if (i <= 1)
 {
  dispeml += cc;
 }
 else 
 if (eml[i + (j + k)].ToString() == "@")
 {
  dispeml += cc;
  k = 0;
  fl = 1;
 }
 else 
 if (eml[i + j].ToString() == "@")
 {
  dispeml += cc;
  fl = 1;
 }
 else 
 if (fl == 1)
 {
  dispeml += cc;
 }
 else
 {
  dispeml += "*";
 }
}

Answer 1

Here is a approach to solve this with Regex

string input = "[email protected]";
string pattern = @"(?<=[\w]{1})[\w-\._\+%]*(?=[\w]{1}@)";
string result = Regex.Replace(input, pattern, m => new string('*', m.Length));
//j**[email protected]

Explanation:

(?<=[\w]{1}) the name has to start with 1 word-character

[\w-\._\+%]* the replacement-part can contain 0-n word characters including -_.+%

(?=[\w]{1}@) the name has to end with one word character followed by a @

Depending on the amount of characters you want to remain unchanged you can change {1} to {2} or something else at the beginning or at the end.