You can filter out every character in the string that’s not a number and then use int.Parse to parse the resulting string, using LINQ something like. Using int.Parse instead of int.TryParse should be ok as we filtered everything that’s not a digit. It may still fail though if the filtered string of numbers exceeds the bounds of an integer.

string original = "123abc";
IEnumerable<char> filtered = original.Where(x => Char.IsDigit(x));
string filteredString = new string(filtered.ToArray());
int number = int.Parse(filteredString);

Or in one line (and using some syntax sugar):

var number = int.Parse(original.Where(Char.IsDigit).ToArray());

You can use Regex to find the numeric values from string.

Regex.Match(text, @"d+").Value;

Below is the working example.

https://dotnetfiddle.net/oSIiOK

Method 1: Using Regular Expressions

using System; using System.Text.RegularExpressions;

public class Program
{
    public static void Main()
    {
        string text = "123abc";
        string numberString = Regex.Match(text, @"d+").Value; // Extracts continuous digits
        int number = int.Parse(numberString); // Converts the string to an integer

        Console.WriteLine(number);
    }
}

Method 2: Manual Iteration

using System;

public class Program
{
    public static void Main()
    {
        string text = "123abc";
        string numberString = "";

        foreach (char c in text)
        {
            if (char.IsDigit(c))
            {
                numberString += c;
            }
        }

        int number = int.Parse(numberString); // Converts the collected digits into an integer

        Console.WriteLine(number);
    }
}

Regular Expressions: This method uses the Regex class to identify and extract digits from the string efficiently. It’s ideal for handling complex patterns quickly but might be less intuitive if you’re not familiar with regex syntax.

Manual Iteration: This method involves checking each character to see if it’s a digit and then forming the integer manually. It offers more control and is straightforward, making it easier to understand if you’re new to regular expressions.

Both methods will correctly convert the string “123abc” to the integer 123. Choose based on your preference for simplicity or flexibility.

If you want to get separate numbers, I would do this:

            string str = "123abc456def";
            List<int> nums = new();
            string num = string.Empty;
            foreach (var c in str.ToCharArray())
            {
                if (Char.IsDigit(c))
                    num += c;
                else
                {
                    if (!num.IsNullOrEmpty())
                        nums.Add(int.Parse(num));
                    num = string.Empty;
                }
            }