C# Get 1st, Last And All Numbers from a string using Linq & Regex

How to extract numbers from a string using C#

Here's two common ways of extracting 1st, last and all numbers from string of mixed characters in C# using Linq & Regular Expressions. Elapsed times are also provided.

Source code

using System; 
using System.Linq; 
using System.Text.RegularExpressions; 
using System.Diagnostics; 
     
public class Program
{
 public static void Main()
 {
      
  Console.WriteLine("Parsing string '123as456'\n"); 
                Stopwatch sw = new Stopwatch(); 
  sw.Start(); 
  //regex get all numbers
  Console.WriteLine(string.Format("{0:00} regex split all numbers", string.Join(null,Regex.Split("123as456", "[^\\d]"))));
   sw.Stop(); 
  Console.WriteLine(string.Format("        ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
  sw.Restart(); 
  //regex get all numbers 
  Console.WriteLine(string.Format("{0:00} regex replace all numbers", Regex.Replace("123as456", @"\D","")));
  sw.Stop(); 
  Console.WriteLine(string.Format("        ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
  sw.Restart();
  //regex get 1st numbers
  Console.WriteLine(string.Format("{0:00} regex match 1st number", Regex.Match("123as456", @"^\d+").ToString())); 
  sw.Stop(); 
  Console.WriteLine(string.Format("       ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
  sw.Restart();   
  //regex get last number
  Console.WriteLine(string.Format("{0:00} regex match last number ", Regex.Match("123as456", @"\d+$").ToString())); 
  sw.Stop(); 
  Console.WriteLine(string.Format("       ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
  sw.Restart();
  Console.WriteLine("Parsing string '222star10bucks'\n"); 
  //linq all numbers in a string successively 
  Console.WriteLine( 
   string.Format("{0:00} linq select all numbers where long format", 
      new string(
             (from t in "222star10bucks"
                      where char.IsDigit(t)
                      select t).ToArray()
                )
       )
                   );
  
   sw.Stop(); 
   Console.WriteLine(string.Format("            ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
   sw.Restart();
   //linq all numbers in a string successively 
          Console.WriteLine(string.Format("{0:00} linq where digits all numbers", new String("222star10bucks".Where(Char.IsDigit).ToArray()))); 
   sw.Stop(); 
   Console.WriteLine(string.Format("         ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
   sw.Restart();
           //linq 1st number in a string      
   Console.WriteLine(string.Format("{0:00} linq takewhile 1st number", new String("222star10bucks".TakeWhile(Char.IsDigit).ToArray()))); 
          sw.Stop(); 
   Console.WriteLine(string.Format("        ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
   sw.Restart();    
   //linq last number in a string, must end in a number
   Console.WriteLine(string.Format("{0:00} linq reverse takewhile last number", string.Concat("222star10".ToArray().Reverse().TakeWhile(char.IsNumber).Reverse())));
   sw.Stop(); 
   Console.WriteLine(string.Format("         ﹂ in {0} ticks",sw.ElapsedTicks.ToString("N0"))); 
  
 }
}