Convert a VERY LARGE binary file into a Base64String incrementally

Question

I need help converting a VERY LARGE binary file (ZIP file) to a Base64String and back again. The files are too large to be loaded into memory all at once (they throw OutOfMe

Answer 1

You can avoid using a secondary buffer by passing offset and length to Convert.ToBase64String, like this:

private void ConvertLargeFile()
{
    using (var inputStream  = new FileStream("C:\\Users\\test\\Desktop\\my.zip", FileMode.Open, FileAccess.Read)) 
    {
        byte[] buffer = new byte[MultipleOfThree];
        int bytesRead = inputStream.Read(buffer, 0, buffer.Length);
        while(bytesRead > 0)
        {
            String base64String = Convert.ToBase64String(buffer, 0, bytesRead);
            File.AppendAllText("C:\\Users\\test\\Desktop\\Base64Zip", base64String); 
            bytesRead = inputStream.Read(buffer, 0, buffer.Length);           
        }
    }
}

The above should work, but I think Rene's answer is actually the better solution.