The out and the ref parameters are used to return values in the same variables, that you pass an argument of a method. These both parameters are very useful when your method needs to return more than one values.

In this article, I will explain how do you use these parameters in your C# applications.

The out Parameter

The out parameter can be used to return the values in the same variable passed as a parameter of the method. Any changes made to the parameter will be reflected in the variable.

public class mathClass
{
public static int TestOut(out int iVal1, out int iVal2)
{
iVal1 = 10;
iVal2 = 20;
return 0;
}
public static void Main()
{
int i, j; // variable need not be initialized
Console.WriteLine(TestOut(out i, out j));
Console.WriteLine(i);
Console.WriteLine(j);
}
}

The ref parameter

The ref keyword on a method parameter causes a method to refer to the same variable that was passed as an input parameter for the same method. If you do any changes to the variable, they will be reflected in the variable.

You can even use ref for more than one method parameters.

namespace TestRefP
{
using System;
public class myClass
{
public static void RefTest(ref int iVal1 )
{
iVal1 += 2;
}
public static void Main()
{
int i; // variable need to be initialized
i = 3;
RefTest(ref i );
Console.WriteLine(i);
}
}
}