Question

I have a stream that is reading the response from a site. I am then saving that stream to text in a text file.

If I then run it again and compare the string from the same site and the text saved in the file it thinks they are different.

When I compare the two strings in a diff tool like WinMerge it find differences at apparently identical points.

What is happening? They are both using the default UTF8 encoder.

I appreciate this may be difficult to follow so I have written a working example for you.

Here is an example:

        var request = WebRequest.Create("http://www.google.com");
        using (var response = request.GetResponse())
        using (var body = response.GetResponseStream())
        using (var googReader = new StreamReader(body))
        using (var googFileStream = File.Open("goog.txt", FileMode.OpenOrCreate))
        using (var fileReader = new StreamReader(googFileStream))
        {
            var googText = googReader.ReadToEnd();
            var fileText = fileReader.ReadToEnd();
            if (!string.Equals(googText, fileText))
            {
                googFileStream.Dispose();
                using (var msnWriter = new StreamWriter(File.Open("goog.txt", FileMode.Create)))
                {
                    msnWriter.Write(googText);
                }
            }
        }

Here is the apparent ‘difference’ as reported by WinMerge. It is apparently at the point between html; charset:

Answer 1

Your code seems fine. It’s just that Google actually returns different contents every time you send a request to it. Other than that you might try simplifying your code and use a site which doesn’t return different contents everytime:

var file = "goog.txt";
using (var client = new WebClient())
{
    var data = client.DownloadString("http://www.google.com");
    if (!File.Exists(file) || !string.Equals(File.ReadAllText(file), data))
    {
        File.WriteAllText(file, data);
    }
}