Detecting browser in ASP.NET using RegEx

Question

I am trying to detect the browser in my C# code by comparing the UserAgent string with some regular expressions.

By the way, in case you are wondering, the reason why I use this approach instead of simply using ASP.NET's HttpBrowserCapabilities object is because I have received a list of more than 200 regex that correspond to 200 browsers and their OS and I can get more detailed information.

Here's a sample:

var sampleUserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0)";
var ieRegEx = "/^Mozilla\/4.0 \(compatible; MSIE ([0-9\.]+); Windows/si";
var success = Regex.Match(sampleUserAgent, regEx.RegularExpression, RegexOptions.IgnoreCase).Success;

In this example I am expecting the regex match to be successful but for some reason, the match returns false. I am guessing that the regex is not quite right.

I didn't write the regex and I am not very familiar with the RegEx syntax so can anybody help me figure out what is wrong with the regex?

Answer 1

I know this does not directly answer the question, but I think you are introducing more problems by using regex for this problem. I would stick with HttpBrowserCapabilities instead unless you have a real need do detect more detailed information.

Answer 2

I found this regex from here

^([^/[:space:]])(/([^[:space:]]))?([[:space:]][[a-zA-Z][a-zA-Z]])? [[:space:]](\((([^()]|(\([^()]\))))\))?[[:space:]]*

which is supposed to match all useragents. They also have a list for more specific useragents.

Answer 3

You should use something like this in C#:

string sampleUserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0)";
string ieRegEx = @"^Mozilla/4.0 \(compatible; MSIE ([0-9\.]+); Windows .*\)$";
bool success = Regex.Match(sampleUserAgent, ieRegEx, RegexOptions.IgnoreCase).Success;

Note I prefer using correct type identifiers rather than var for simple types.

Also, I personally would just stick to using Browser Caps as it would be much less hassle, especially if you aren't good with reg-ex.