TocnoRijesen

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        struct RetrunFromFunction
        {
            public bool semicolon;
            public bool comma;
            public bool period;
        }

        static void Main(string[] args)
        {
            Console.Write("Enter string: ");
            var input = Console.ReadLine();
            var Result = Function(input);

            Console.WriteLine("Ima tocku: " + Result.comma);
            Console.WriteLine("Ima zarez: " + Result.period);
            Console.WriteLine("Ima tocku zarez: " + Result.semicolon);

            Console.WriteLine("Press any key to terminate");
            Console.ReadLine();
        }

        private static RetrunFromFunction Function(string input)
        {
            var Result = new RetrunFromFunction
            {
                semicolon = false,
                comma = false,
                period = false
            };

            for (int i = 0; i < input.Length; i++)
            {
                switch (input[i])
                {
                    case '.':
                        Result.period = true;
                        break;
                    case ',':
                        Result.period = true;
                        break;
                    case ';':
                        Result.semicolon = true;
                        break;
                }
            }
            return Result;
        }
    }
}