`Regex.Replace`, digits

A C# Regex can match numeric characters. This helps with certain requirements. Some programs need to remove digit character to clean up input data.

The "\d" metacharacter matches digit characters. Conversely the "\D" metacharacter matches non-digit characters. Uppercase means "not."

In this example, the characters with the exact values 0 through 9 must be removed from the string. They are not replaced with other characters but entirely removed.

Part 1 We specify 3 different example strings and pass them to the RemoveDigits static method.

Part 2 The "\d" pattern string specifies a single digit character (0 through 9). The characters are replaced with an empty string.

Result The 3 strings have their numbers removed. The Regex allocates new string data and returns a reference to that object data.

using System;
using System.Text.RegularExpressions;

class Program
{
    /// <summary>
    /// Remove digits from string.
    /// </summary>
    public static string RemoveDigits(string key)
    {
        // Part 2: use Regex.Replace with a metacharacter, and replace with an empty string.
        return Regex.Replace(key, @"\d", "");
    }

    static void Main()
    {
        // Part 1: remove the digits in these example input strings.
        string input1 = "Dot123Net456Perls";
        string input2 = "101Dalmatations";
        string input3 = "4 Score";

        string value1 = RemoveDigits(input1);
        string value2 = RemoveDigits(input2);
        string value3 = RemoveDigits(input3);

        Console.WriteLine(value1);
        Console.WriteLine(value2);
        Console.WriteLine(value3);
    }
}DotNetPerls
Dalmatations
 Score

Performance

The performance of Regex.Replace is far from ideal. For more speed, you could use a char array and dynamically build up the output string.

Finally You could return that character array as a string using the new string constructor.

You can remove number characters in strings using the C# language. This requirement is common, and useful in the real world. We proved the method's correctness.

Regex.Replace, digits

Performance

`Regex.Replace`, digits