How to mask string?

Question

I have a string with value \"1131200001103\".

How can I display it as a string in this format \"11-312-001103\" using Response.Write(value)?

Thanks

Answer 1

I wrote a quick extension method for same / similar purpose (similar in a sense that there's no way to skip characters).

Usage:

var testString = "12345";
var maskedString = testString.Mask("##.## #"); // 12.34 5

Method:

public static string Mask(this string value, string mask, char substituteChar = '#')
{
    int valueIndex = 0;
    try
    {
        return new string(mask.Select(maskChar => maskChar == substituteChar ? value[valueIndex++] : maskChar).ToArray());
    }
    catch (IndexOutOfRangeException e)
    {
        throw new Exception("Value too short to substitute all substitute characters in the mask", e);
    }
}