Format social security number

readme.md

Given a string var value = "123458899"; Format with dashes ➡️ 123-45-8899

StringHelpers.cs

using System.Text.RegularExpressions;


public static partial class StringHelpers
{
    public static string FormatSocial1(string value)
    {
        if (string.IsNullOrEmpty(value))
            return value;

        if (IsInteger(value) == false)
            throw new ArgumentException("Invalid SSN");

        return SplitRegex().Replace(value, "$1-$2-$3");
    }

    public static string FormatSocial2(string value)
    {
        if (string.IsNullOrEmpty(value))
            return value;

        if (IsInteger(value) == false)
            throw new ArgumentException("Invalid SSN");

        return $"{value[..3]}-{value[3..5]}-{value[^4..]}";
    }

    [GeneratedRegex(@"(\d{3})(\d{2})(\d{4})")]
    private static partial Regex SplitRegex();
    public static bool IsInteger(string value) 
        => value.All(c => c is >= '0' and <= '9');
}