We can pass parameters to a method by value or by reference. By DEFAULT all value types are PASSED by value where as all reference types are passed by reference. By default, when a value type is passed to a method, a copy is passed instead of the object itself. Therefore, changes to the argument have no effect on the original copy in the calling method.An example is shown below.

using System;
NAMESPACE Demo
{
class Program
{
public static void Main()
{
INT I = 10;
int K = Function(I);
Console.WriteLine("I = " + I);
Console.WriteLine("K = " + K);
}
public static int Function(int Number)
{
int ChangedValue = Number + 1;
return ChangedValue;
}
}
}

By default, reference types are passed by reference. When an object of a reference type is passed to a method, the reference points to the original object, not a copy of the object. Changes made through this reference will therefore be reflected in the calling method. Reference types are created by using the class keyword as shown in the example below.

using System;
namespace Demo
{
class Program
{
public static void Main()
{
ReferenceTypeExample Object = new ReferenceTypeExample();
Object.Number = 20;
Console.WriteLine("Original Object Value = " + Object.Number);
Function(Object);
Console.WriteLine("Object Value after passed to the method= " + Object.Number);
}
public static void Function(ReferenceTypeExample ReferenceTypeObject)
{
ReferenceTypeObject.Number = ReferenceTypeObject.Number + 5;
}
}
class ReferenceTypeExample
{
public int Number;
}
}

We can pass parameters to a method by value or by reference. By default all value types are passed by value where as all reference types are passed by reference. By default, when a value type is passed to a method, a copy is passed instead of the object itself. Therefore, changes to the argument have no effect on the original copy in the calling method.An example is shown below.

using System;
namespace Demo
{
class Program
{
public static void Main()
{
int I = 10;
int K = Function(I);
Console.WriteLine("I = " + I);
Console.WriteLine("K = " + K);
}
public static int Function(int Number)
{
int ChangedValue = Number + 1;
return ChangedValue;
}
}
}

By default, reference types are passed by reference. When an object of a reference type is passed to a method, the reference points to the original object, not a copy of the object. Changes made through this reference will therefore be reflected in the calling method. Reference types are created by using the class keyword as shown in the example below.

using System;
namespace Demo
{
class Program
{
public static void Main()
{
ReferenceTypeExample Object = new ReferenceTypeExample();
Object.Number = 20;
Console.WriteLine("Original Object Value = " + Object.Number);
Function(Object);
Console.WriteLine("Object Value after passed to the method= " + Object.Number);
}
public static void Function(ReferenceTypeExample ReferenceTypeObject)
{
ReferenceTypeObject.Number = ReferenceTypeObject.Number + 5;
}
}
class ReferenceTypeExample
{
public int Number;
}
}