Jemand

using System;

class Little_Calculator
{
    public static void Main()
    {
        string console_input;
        int op_pos;
        float zahl1;
        float zahl2;

        for(;;)
        {
            Console.Write("Operation: ");
            console_input = Console.ReadLine();

            console_input = console_input.Replace(" ","");
            op_pos = input_check(console_input);

            Console.WriteLine("Operator-Position= {0}", op_pos);
        }
        
    }

    public static int input_check(string str_var)
    {
        int i;
        string[] op = {"+", "plus", "-", "minus", "x", "*", "mal", "/", ":", "geteilt"};
                foreach (string s in op)
        {
            i = str_var.IndexOf(s);
            if (i != -1)
            {
                return i;
            }
            return -1;
        }
        return -1;
    }

}