Convert.ToBase64String() Method in C#

The Convert.ToBase64String() method in C# is used to convert the value of an array of 8-bit unsigned integers to its equivalent string representation that is encoded with base-64 digits. This is commonly used for encoding binary data into a text format that can be safely transmitted or stored.

Syntax

Following is the syntax −

public static string ToBase64String(byte[] inArray);

Parameters

• inArray − An array of 8-bit unsigned integers to be converted to Base64 string.

Return Value

Returns a string representation of the contents of the byte array encoded in Base64.

Example

Let us now see an example to implement the Convert.ToBase64String() method −

using System;

public class Demo {
   public static void Main() {
      byte[] val1 = {5, 10, 15, 20, 25, 30};
      string str = Convert.ToBase64String(val1);
      Console.WriteLine("Base 64 string: '{0}'", str);
      
      byte[] val2 = Convert.FromBase64String(str);
      Console.WriteLine("Converted byte value: {0}", BitConverter.ToString(val2));
   }
}

The output of the above code is −

Base 64 string: 'BQoPFBke'
Converted byte value: 05-0A-0F-14-19-1E

Using ToBase64String() with Text

A common use case is encoding text data to Base64 format −

using System;
using System.Text;

public class TextToBase64 {
   public static void Main() {
      string originalText = "Hello World!";
      byte[] textBytes = Encoding.UTF8.GetBytes(originalText);
      string base64String = Convert.ToBase64String(textBytes);
      
      Console.WriteLine("Original text: {0}", originalText);
      Console.WriteLine("Base64 encoded: {0}", base64String);
      
      // Decode back to verify
      byte[] decodedBytes = Convert.FromBase64String(base64String);
      string decodedText = Encoding.UTF8.GetString(decodedBytes);
      Console.WriteLine("Decoded text: {0}", decodedText);
   }
}

The output of the above code is −

Original text: Hello World!
Base64 encoded: SGVsbG8gV29ybGQh
Decoded text: Hello World!

Using ToBase64String() with Different Data Types

You can also convert other data types by first converting them to byte arrays −

using System;

public class DataTypeEncoding {
   public static void Main() {
      // Integer to Base64
      int number = 12345;
      byte[] intBytes = BitConverter.GetBytes(number);
      string intBase64 = Convert.ToBase64String(intBytes);
      Console.WriteLine("Integer {0} as Base64: {1}", number, intBase64);
      
      // Double to Base64
      double decimalValue = 123.456;
      byte[] doubleBytes = BitConverter.GetBytes(decimalValue);
      string doubleBase64 = Convert.ToBase64String(doubleBytes);
      Console.WriteLine("Double {0} as Base64: {1}", decimalValue, doubleBase64);
      
      // Boolean to Base64
      bool boolValue = true;
      byte[] boolBytes = BitConverter.GetBytes(boolValue);
      string boolBase64 = Convert.ToBase64String(boolBytes);
      Console.WriteLine("Boolean {0} as Base64: {1}", boolValue, boolBase64);
   }
}

The output of the above code is −

Integer 12345 as Base64: OTA=
Double 123.456 as Base64: F9nPVDHedkA=
Boolean True as Base64: AQ==

Common Use Cases

• Data transmission − Encoding binary data for safe transmission over text-based protocols like HTTP or email.

• Configuration storage − Storing binary configuration data in XML or JSON files.

• Image encoding − Embedding images in HTML or CSS using data URLs.

• Cryptographic operations − Encoding encrypted data or cryptographic keys for storage or transmission.

Conclusion

The Convert.ToBase64String() method is essential for encoding binary data into a Base64 string format. It's particularly useful when you need to transmit or store binary data in environments that only support text, ensuring data integrity and compatibility across different systems.