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What are the differences between ref and out parameters in C#?
Ref Parameter
A reference parameter is a reference to a memory location of a variable. When you pass parameters by reference, unlike value parameters, a new storage location is not created for these parameters.
You can declare the reference parameters using the ref keyword. The following is an example −
Example
using System;
namespace CalculatorApplication {
class NumberManipulator {
public void swap(ref int x, ref int y) {
int temp;
temp = x; /* save the value of x */
x = y; /* put y into x */
y = temp; /* put temp into y */
}
static void Main(string[] args) {
NumberManipulator n = new NumberManipulator();
/* local variable definition */
int a = 100;
int b = 200;
Console.WriteLine("Before swap, value of a : {0}", a);
Console.WriteLine("Before swap, value of b : {0}", b);
/* calling a function to swap the values */
n.swap(ref a, ref b);
Console.WriteLine("After swap, value of a : {0}", a);
Console.WriteLine("After swap, value of b : {0}", b);
Console.ReadLine();
}
}
}Output
Before swap, value of a : 100 Before swap, value of b : 200 After swap, value of a : 200 After swap, value of b : 100
Out Parameter
A return statement can be used for returning only one value from a function. However, using out parameter, you can return two values from a function.
The following is an example −
Example
using System;
namespace CalculatorApplication {
class NumberManipulator {
public void getValue(out int x ) {
int temp = 10;
x = temp;
}
static void Main(string[] args) {
NumberManipulator n = new NumberManipulator();
/* local variable definition */
int a = 150;
Console.WriteLine("Before method call, value of a : {0}", a);
/* calling a function to get the value */
n.getValue(out a);
Console.WriteLine("After method call, value of a : {0}", a);
Console.ReadLine();
}
}
}Output
Before method call, value of a : 150 After method call, value of a : 10
Updated on: 20-Jun-2020
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