How To Format String As Phone Number In C#

In this article, we will learn how to format string as the phone number in C#.

In the example given below, we are passing a string to MaskPhoneNumber() method. MaskPhoneNumber() method returns a string as the formatted phone number. If we didn’t pass anything to MaskPhoneNumber() method it will return ‘Phone number is required !!!‘.

using System;
using System.Text.RegularExpressions;

namespace Mask_PhoneNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(MaskPhoneNumber("44575113620"));
            Console.WriteLine(MaskPhoneNumber(""));
            Console.WriteLine(MaskPhoneNumber("9876_543210"));
            Console.WriteLine(MaskPhoneNumber("Test"));
            Console.WriteLine(MaskPhoneNumber("0987654321"));
        }
        public static string MaskPhoneNumber(string value)
        {
            try
            {
                if (!string.IsNullOrEmpty(value))
                {
                    value = Regex.Replace(value, @"\D", ""); // to remove special characters
                    return (double.Parse(value).ToString("(###) ###-####"));
                }
                else
                {
                    return "Phone number is required !!!";
                }
            }
            catch (Exception)
            {
                return "Something went wrong !!!";
            }
        }
    }
}

Output:

As we can see MaskPhoneNumber(“0987654321”) returns (98) 765-4321 where 0 is missing. So, to solve this we have to change code as given below.

using System;
using System.Text.RegularExpressions;

namespace Mask_PhoneNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(MaskPhoneNumber("44575113620"));
            Console.WriteLine(MaskPhoneNumber(""));
            Console.WriteLine(MaskPhoneNumber("9876_543210"));
            Console.WriteLine(MaskPhoneNumber("Test"));
            Console.WriteLine(MaskPhoneNumber("0987654321"));
        }
        public static string MaskPhoneNumber(string value)
        {
            try
            {
                if (!string.IsNullOrEmpty(value))
                {
                    value = Regex.Replace(value, @"\D", ""); // to remove the special characters
                    var phoneMask = value.StartsWith("0") ? "(0##) ###-####" : "(###) ###-####";
                    return (double.Parse(value).ToString(phoneMask));
                }
                else
                {
                    return "Phone number is required !!!";
                }
            }
            catch (Exception)
            {
                return "Something went wrong !!!";
            }
        }
    }
}

Output:

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