How to make a function that returns value from a list in C#-CodePudding

I have a list filled with objects. I have to make a function that when given a certain value of one of the class atributes, gives back another one. In my case, when you specify the "index", the function will return "standysp"(I'm sorry if I can't explain it to well). I need to make this function work but I don't even know when to start. Here is my Code:

using System;
using FirebirdSql.Data.FirebirdClient;
using System.Collections.Generic;

namespace dokselect
{
    class PozycjaMagazynowa
    {
        public double standysp;
        public string nazwagrupy;
        public string index;
        public string nazwadl;
    }
    class Program
    {
        public static void Main()
        {

            string conn = "SECRET";
            FbConnection myConnection = new FbConnection(conn);
            FbDataReader myReader = null;

            string sql = "select STANMAG.standysp,GRUPAKART.nazwagrupy, KARTOTEKA.indeks, kartoteka.nazwadl FROM stanmag JOIN kartoteka using(ID_KARTOTEKA) JOIN wystgrkart using(ID_KARTOTEKA) JOIN grupakart using(ID_GRUPAKART) ORDER BY nazwagrupy;";
            FbCommand myCommand = new FbCommand(sql, myConnection);

            myConnection.Open();
            myReader = myCommand.ExecuteReader();

            List<PozycjaMagazynowa> lista1 = new List<PozycjaMagazynowa>();
            double standysp;
            string nazwagrupy;
            string index;
            string nazwadl;
            while (myReader.Read())
            {
                standysp = Convert.ToDouble(myReader[0]);
                nazwagrupy = myReader[1].ToString();
                index = myReader[2].ToString();
                nazwadl = myReader[3].ToString();
                lista1.Add(new PozycjaMagazynowa { standysp = standysp, nazwagrupy = nazwagrupy, index = index, nazwadl = nazwadl });

                
            }
       
            myConnection.Close();
            Console.WriteLine(lista1.Count);

                            //LISTA DONE

            void wyswietl()
            {
                //????????
            }
        }
    }
}

CodePudding user response：

I'm not sure you're doing it the right way. First the List you create is not accessible to others methods. Secund, maybe the List is not appropriate and you may use a HashSet<T> or Dictionnary with your PozycjaMagazynowa class implementing IEqualityComparer

CodePudding user response：

I used this method and it worked thank you for help:

double wyswietl()
        {
            string myIndex="WSIP_MAT_GIM";
            var result = lista1.FirstOrDefault(lista1 => lista1.index == myIndex).standysp;
            Console.WriteLine(myIndex   " Zostalo zwrocone przez funkcje");
            Console.WriteLine(result   " - to stan dyspozycyjny pasujacy do podanego indexu");
            return result;
        }
        wyswietl();