Regular expressions is one of the best ways to work with text. One popular task for Regexp is to get a part of word or expression.Let’s try to get first part from word "Heli-copter", the part that before character "-". 

string text = "Heli-copter";

 

1. Solution with Regex Match everything till the first "-"

Match result = Regex.Match(text, @"^.*?(?=-)");

Comments for solution:

^ match from the start of the string

.*? match any character (.), zero or more times (*) but as less as possible (?)

(?=-) till the next character is a "-" (this is a positive look ahead)

 

2. Regex Match anything that is not a "-" from the start of the string

Match result2 = Regex.Match(text, @"^[^-]*");

Comments for solution:

[^-]* match any character that is not a "-" zero or more times

 

3. Regex Match anything that is not a "-" from the start of the string till a "-"

Match result3 = Regex.Match(text, @"^([^-]*)-");

Comments for solution:

This regex will only match if there is "-" in the string, but the result is then found in capture group 1.

4. Convert string to string array using Split and spacer character "-"

string[] result4 = text.Split('-');

Comments for solution:

Result is a Array of strings, the part before the first "-" is the first item in the Array, result4[0]

 

5. Substring till the first "-"

string result5 = text.Substring(0, text.IndexOf("-"));

Comments for solution:

Get the substring from text from the start till the first occurrence of "-" (text.IndexOf("-")). This works only if there is a "-" in a string, otherwise you get the exception because IndexOf("-") when no "-" return "-1".

 

Full code here:

            string text = "Heli-copter";

            Match result1 = Regex.Match(text, @"^.*?(?=-)");
            Match result2 = Regex.Match(text, @"^[^-]*");
            Match result3 = Regex.Match(text, @"^([^-]*)-");
            string[] result4 = text.Split('-');

            string result5 = text.Substring(0, text.IndexOf("-"));


            Console.WriteLine("Result 1: " + result1.ToString());
            Console.WriteLine("Result 2: " + result2.ToString());
            Console.WriteLine("Result 3: " + result3.ToString());
            Console.WriteLine("Result 4: " + string.Join(" , ", result4));
            Console.WriteLine("Result 5: " + result5);

 

 




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