I need to make a number validation for specified string. The problem is, the string could be a large number, larger than any numeric type in C# can represent, so I can't use TryParse functions, because they will give only information about whether they can convert to those types.
It should take into account -/+, separator, and current culture settings.
I found some solutions using regular expressions, but all of them miss some details. And I'm not good at regular expressions
You can use BigInteger if you are using C# 4.0 and the numbers are integers.
It Represents an arbitrarily large signed integer.
Use the TryParse method to avoid the possible exception from Parse (unless you are certain that the passed in string will always be a valid integer).
If you use .NET 4.0 you can use BigInteger. It contains a TryParse that excepts an IFormatProver that will do what you need. BigInteger has an unlimited size, so it is not possible that the numbers you need are larger than what BigInteger can handle.
Take a look at http://www.regexlib.com/Search.aspx?k=numeric&c=-1&m=5&ps=20. http://regexlib.com/ contains many examples of regular expressions, and there must be one that suits your requirements.