Back to Basics — Reading a File into Memory Stream

Today I was asked to help a developer with a simple task she had. That task included reading an image file into a memory stream in order to send the image through an e-mail attachment. This post will show you how to do exactly that.

Reading a File into Memory Stream

Here is the code for reading the file into a memory stream:

using (FileStream fileStream = File.OpenRead(filePath))
{
    MemoryStream memStream = new MemoryStream();
    memStream.SetLength(fileStream.Length);
    fileStream.Read(memStream.GetBuffer(), 0, (int)fileStream.Length);
}

That’s it for the reading part. Pay attention to use the using statement in order to dispose the FileStream after you use it.

Adding a MemoryStream as Attachment to a MailMessage

In order to use a stream as an attachment for an e-mail message object all you have to do is to write the following code:

msg.Attachments.Add(new Attachment(memStream, filename, MediaTypeNames.Image.Jpeg));

In the code sample msg is an instance of a MailMessage class, memStream is the MemoryStream (such as the memory stream from the previous code sample) and filename is the name of the file in the attachment. Since I know that the image is jpeg then I use the MediaTypeNames.Image.Jpeg.

Summary

Reading a file into a stream is a very basic thing to know. In the post I showed how to read an image into a memory stream and also how to attach it into a mail message object.

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Originally published at blogs.microsoft.co.il on March 3, 2011.