using System;

class Program

{

    static void Main(string[] args)

    {

        Console.WriteLine("223232-1.jpg".GetUntil('-'));

        Console.WriteLine("443-2.jpg".GetUntil('-'));

        Console.WriteLine("34443553z-5.jpg".GetUntil('-'));

​

        Console.ReadKey();

    }

}

​

static class StringExtensions

{

        /// <summary>

        /// Get substring until first occurrence of given character has been found. Returns the whole string if character has not been found.

        /// </summary>

        public static string GetUntil(this string that, char @char)

        {

            return that[..(IndexOf() == -1 ? that.Length : IndexOf())];

            int IndexOf() => that.IndexOf(@char);

        }

}