Numbers only regex (digits only) C#
Numbers only (or digits only) regular expressions can be used to validate if a string contains only numbers.
Basic numbers only regex
Below is a simple regular expression that allows validating if a given string contains only numbers:
new Regex("^\\d+$")
Enter a text in the input above to see the result
Example code in C#:
using System.Text.RegularExpressions;
using System.Linq;
using System;
public class Program
{
public static void Main()
{
// Validate number
Regex validateNumberRegex = new Regex("^\\d+$");
Console.WriteLine(validateNumberRegex.IsMatch("42")); // prints True
// Extract number from a string
Regex extractNumberrRegex = new Regex("\\d+");
string [] extracted = extractNumberrRegex.Matches("Your message was viewed 203 times.")
.Cast<Match>()
.Select(m => m.Value)
.ToArray();
Console.WriteLine(String.Join(",", extracted)); // prints 203
}
}
Real number regex
Real number regex can be used to validate or exact real numbers from a string.
Pattern.compile("^(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)$")
Enter a text in the input above to see the result
Example code in C#:
using System.Text.RegularExpressions;
using System.Linq;
using System;
public class Program
{
public static void Main()
{
// Validate real number
Regex validateNumberRegex = new Regex("^(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)$");
Console.WriteLine(validateNumberRegex.IsMatch("121220.22")); // prints True
// Extract real number from a string
Regex extractNumberRegex = new Regex("(?:-(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))|(?:0|(?:[1-9](?:\\d{0,2}(?:,\\d{3})+|\\d*))))(?:.\\d+|)");
string [] extracted = extractNumberRegex.Matches("Pi equals to 3.14")
.Cast<Match>()
.Select(m => m.Value)
.ToArray();
Console.WriteLine(String.Join(",", extracted)); // prints 3.14
}
}
Notes on number only regex validation
In C# you can also validate number by trying to parse it:
int.TryParse("123");
