C# regular expression engine does not work

Question

Hello guys,

i'm doing the simplest regex.match ever, i am giving the Regex.Match a pattern of one character and it returns no match at all, and i made sure the input text contains a lot of that character?

i checked all the usings.

its just very weird.

any help would be appreciated!

Thanks.

EDIT:

my sample is "doing any type of matching is simply not WORKING" returns an empty match

Match m=Regex.Match(@"c","abcdc");

the code is compiled with no errors, so why the NO MATCHING!!

Answer 1

I assure you, the regular expression works. I have used it many, many times.

This will put the string "d" in the variable s:

string s = System.Text.RegularExpressions.Regex.Match("asdf", "d").Value;

If that doesn't work, perhaps you have some strange culture setting that affects how strings are compared? Does System.Globalization.CultureInfo.CurrentCulture.DisplayName return an expected value?

Answer 2

EDIT: based on your edit the issue is that you're using the parameters out of order. You need to switch the order and supply the input (string source to find a match in) then the pattern (what to match against).

In fact, this order is specified for you by the IntelliSense as depicted in this image:

It usually helps to match the naming suggested by the IntelliSense or refer to it to ensure the proper items are being passed in.

---

What is the character being used? Chances are you're trying to use a character that is actually a metacharacter which holds special meaning in regex.

For example:

string result = Regex.Match("$500.00", "$").Value;

The above wouldn't return anything since $ is a metacharacter that needs to be escaped:

string result1 = Regex.Match("$500.00", @"\$").Value;  // or
string result2 = Regex.Match("$500.00", "\\$").Value;  // or
string result3 = Regex.Match("$500.00", Regex.Escape("$")).Value;

For a list of common metacharacters that need to be escaped look at the Regex.Escape documentation.

Answer 3

I recommend that you get RegExBuddy. That way you can check your regex's against a test file and make sure they should return something and that you didn't mess up your expression.

http://www.regexbuddy.com/

Answer 4

You have the parameters in the wrong order in your example:

Match m=Regex.Match(@"c","abcdc");

This code means that you try to find the string "abcdc" in the string "c", try it the other way around and it should work better, ie:

Match m=Regex.Match("abcdc", "c");

Also, the fact that your code compiles doesn't mean that it will necessarily find a match...

Here is the documentation for Regex.Match.