Viewing Embedded Images in HTML E-mail (Base64)
January 11, 2008
Problem: you have image data from an HTML e-mail, but don't know what to do with it. When you save it to disk it comes out with a weird string instead of binary data.
Solution: pretty simple, you just have to know the terms. This string of data is actually Base64 encoded, which means that the binary data has been converted to a text string for easy transmission over text protocols. .Net Developer's Journal has a good full explanation. All you have to do is convert the string over to a byte array using Convert.FromBase64String, then save your new byte[].
And what if the string is itself transmitted as a byte array? Well, simply convert each byte into a char and then convert the resulting array into the new byte array:
// Convert "string" to chars
byte[] byteEncodedString = ...;
char[] charBytes = new char[byteEncodedString.Length];
for (int i = 0; i < byteEncodedString.Length; i++)
charBytes[i] = Convert.ToChar(byteEncodedString[i]);
// Convert chars back to bytes
byte[] newBytes = Convert.FromBase64CharAray(charBytes, 0, charBytes.Length);
// Save
using (FileStream fs = new FileStream(mypath, FileMode.Create))
fs.Write(newBytes, 0, newBytes.Length);