How to return 2 Lists or Arrays from a function?

Question

Hi, How can I return 2 Lists or Arrays from a function? Thanks

Bruce Roeser · Answer

Here's an example of how to do it. Remember that in C# parameter values are passed by value by default. In the case of the two arrayLists this has the appearance of passing by reference, however what you are passing is the address of the arrays when you make this call which is why it works. If you passed a primitive variable like an "int" and tried to assign the value it wouldn't work this way. Be sure to study the concept of parameter passing or you may confuse yourself here. -b using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Collections; namespace LangTest { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void btnTwoArray_Click(object sender, EventArgs e) { ArrayList ar1, ar2; ar1 = new ArrayList(); ar2 = new ArrayList(); FillArrays(ar1, ar2); for (int i=0; i Console.WriteLine("ar1[" + i + "] = " + ar1[i].ToString()); } for (int i=0; i Console.WriteLine("ar2[" + i + "] = " + ar2[i].ToString()); } } private void FillArrays(ArrayList ar1, ArrayList ar2) { ar1.Add("A"); ar1.Add("B"); ar1.Add("C"); ar2.Add("X"); ar2.Add("Y"); ar2.Add("Z"); } } }

Sam Hobbs · Answer

Bruce's sample is good. There are many other possibilities too. You could create a class that has the collections as members and then pass an instance of the class to the function. If you do that, then you could even make the function that fills the collections a member of the new class. The best solution depends on your requirements and preferencs.

How to return 2 Lists or Arrays from a function?

Answers (2)