A regular expression is a pattern that could be matched against an input text.
The .Net framework provides a regular expression engine that allows such matching.
A pattern consists of one or more character literals, operators, or constructs.
Here are basic pattern metacharacters used by RegEx −
* = zero or more ? = zero or one ^ = not [] = range
The ^ symbol is used to specify not condition.
the [] brackets if we are to give range values such as 0 - 9 or a-z or A-Z
class Program{ public static void Main(){ string num = "123dh"; Regex regex = new Regex(@"^-?[0-9][0-9,\.]+$"); var res = regex.IsMatch(num); System.Console.WriteLine(res); } }
False
class Program{ public static void Main(){ string num = "123"; Regex regex = new Regex(@"^-?[0-9][0-9,\.]+$"); var res = regex.IsMatch(num); System.Console.WriteLine(res); } }
True
class Program{ public static void Main(){ string num = "123.67"; Regex regex = new Regex(@"^-?[0-9][0-9,\.]+$"); var res = regex.IsMatch(num); System.Console.WriteLine(res); } }
True