Passing By Value Vs By Ref C#
A value-type variable contains its data directly as opposed to a reference-type variable, which contains a reference to its data. Passing a
value-type variable to a method by value means passing a copy of the variable
to the method. Any changes to the parameter that take place inside the method
have no effect on the original data stored in the argument variable. If you
want the called method to change the value of the parameter, you must pass it
by reference, using the ref or out keyword. For simplicity, the following
examples use ref.
Bool, byte, char, decimal, double, enum, float, int, long, sbyte, short, struct, uint, ulong, ushort
Class, delegate, dynamic, interface, object, string
C# Example
private void button1_Click(object sender, EventArgs e)
{
int i
= 100;
PassByVal(i); // Don't change original value
button1.Text = i.ToString(); // OutPut is : 100
PassByRef(ref i); // Change original value
button1.Text = i.ToString(); // OutPut is : 110
}
private void PassByRef(ref int i)
{ i += 10; }
private void PassByVal(int i)
{ i += 10; }
More Difference
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Value Type
|
Reference Type
|
|
They are stored
on stack
|
They are stored
on heap
|
|
Contains actual
value
|
Contains
reference to a value
|
|
Cannot contain
null values. However this can be achieved by nullable types
|
Can contain null
values.
|
|
Value type is
popped on its own from stack when they go out of scope.
|
Required garbage
collector to free memory.
|
|
Memory is
allocated at compile time
|
Memory is
allocated at run time
|
