Recipe 2.12. Decoding a Base64-Encoded BinaryProblemYou have a String that contains information such as a bitmap encoded as base64. You need to decode this data (which may have been embedded in an email message) from a String into a byte[] so that you can access the original binary. SolutionUsing the static method Convert.FromBase64String on the Convert class, an encoded String may be decoded to its equivalent byte[]: using System; public static byte[] Base64DecodeString(string inputStr) { byte[] decodedByteArray = Convert.FromBase64String(inputStr); return (decodedByteArray); } DiscussionThe static FromBase64String method on the Convert class makes decoding an encoded base64 string a simple matter. This method returns a byte[] that contains the decoded elements of the String. If you receive a file via email, such as an image file (.bmp), that has been converted to a string, you can convert it back into its original bitmap file, using something like the following: byte[] imageBytes = Base64DecodeString(bmpAsString); using (FileStream fstrm = new FileStream(@"C:\winnt_copy.bmp", FileMode.CreateNew, FileAccess.Write)) { using (BinaryWriter writer = new BinaryWriter(fstrm)) { writer.Write(imageBytes); } } In this code, the bmpAsString variable was obtained from the code in the Discussion section of Recipe 2.11. The imageBytes byte[] is the bmpAsString String converted back to a byte[], which can then be written back to disk. To encode a byte[] to a String, see Recipe 2.13. See AlsoSee Recipe 2.11; see the "Convert.FromBase64CharArray Method" topic in the MSDN documentation. |