Question

To encode a string

Code:
public string base64Encode(string data)
{
    try
    {
        byte[] encData_byte = new byte[data.Length];
        encData_byte = System.Text.Encoding.UTF8.GetBytes(data);    
        string encodedData = Convert.ToBase64String(encData_byte);
        return encodedData;
    }
    catch(Exception e)
    {
        throw new Exception("Error in base64Encode" + e.Message);
    }
}
and to decode

Code:
public string base64Decode(string data)
{
    try
    {
        System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();  
        System.Text.Decoder utf8Decode = encoder.GetDecoder();

        byte[] todecode_byte = Convert.FromBase64String(data);
        int charCount = utf8Decode.GetCharCount(todecode_byte, 0, todecode_byte.Length);    
        char[] decoded_char = new char[charCount];
        utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0);                   
        string result = new String(decoded_char);
        return result;
    }
    catch(Exception e)
    {
        throw new Exception("Error in base64Decode" + e.Message);
    }
}

Answer 1

You haven’t said what error you’re getting, but surely your second code should simply be:

return Encoding.UTF8.GetString(Convert.FromBase64String(data));

• You don’t need to create a new UTF8Encoding
• You don’t need to worry about decoders explicitly

Additionally, your exception handling is nasty – the stack trace would already show where the error occurs, but by catching it and rethrowing just Exception you’re hiding the original exception type. Just remove the try/catch blocks from both your methods. (And rename them to match .NET naming conventions.)

Basically, your code can look as simple as this:

public static string Base64AndUtf8Encode(string text)
{
    return Convert.ToBase64String(Encoding.UTF8.GetBytes(text));
}

public static string Base64AndUtf8Decode(string base64)
{
    return Encoding.UTF8.GetString(Convert.FromBase64String(base64));
}

Obviously you can split it into separate statements if you want, but it can stil be pretty short:

public static string Base64AndUtf8Encode(string text)
{
    byte[] bytes = Encoding.UTF8.GetBytes(text);
    return Convert.ToBase64String(bytes);
}

public static string Base64AndUtf8Decode(string base64)
{
    bytes[] bytes = Convert.FromBase64String(base64);
    return Encoding.UTF8.GetString(bytes);
}