Decoding Base64 in C#

To decode Base64 strings using the Convert class in the System namespace. The FromBase64String method takes a Base64 encoded string as input and returns the original byte array. From there, we can convert the byte array into a normal string using the Encoding class.

using System;
using System.Text;

class Program
{
    static void Main()
    {
        // Base64 encoded string
        string base64String = "SGVsbG8gd29ybGQh";

        // Decode Base64 string
        byte[] bytes = Convert.FromBase64String(base64String);

        // Convert byte array to string
        string result = Encoding.UTF8.GetString(bytes);

        // Output the result
        Console.WriteLine("Decoded String: " + result);
    }
}

Output:

Decoded String: Hello world!

In this example, the Base64 encoded string "SGVsbG8gd29ybGQh" is successfully decoded back to its original form, "Hello world!".