C# Regex.Split Numbers

Regex.Split can extract numbers from strings. You want to get all the numbers that are found in a string inside your C# program. Ideal for this purpose is the Regex.Split method with a delimiter code. Using an example, we describe an effective way of acquiring all positive integers in a string.

This C# example program uses Regex.Split to get numbers from a string.

Example

As we begin, please notice how the System.Text.RegularExpressions namespace is included. The const input string has four numbers in it: they are one or two digits long. To acquire the numbers, we use the format string @"\D+" in the Regex.Split method; this indicates that we want to use any number of one or more non-digit characters as a delimiter.

Program that uses Regex.Split on string [C#]

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
	const string input = "There are 4 numbers in this string: 40, 30, and 10.";
	// Split on one or more non-digit characters.
	string[] numbers = Regex.Split(input, @"\D+");
	foreach (string value in numbers)
	{
	    if (!string.IsNullOrEmpty(value))
	    {
		int i = int.Parse(value);
		Console.WriteLine("Number: {0}", i);
	    }
	}
    }
}

Output

Number: 4
Number: 40
Number: 30
Number: 10

Parsing the numbers. The Regex.Split method will return the numbers in string form. The result array may also contain empty strings; to avoid parsing errors, we use the string.IsNullOrEmpty method. Finally, we invoke the int.Parse method to get integers.

Summary

In this demonstration, we extracted four integers that were embedded in a string literal, and then converted them to integers. The Regex.Split method is useful for this purpose, and is much better than the string.Split method because it allows more flexible delimiters.