Part 16 - C# Tutorial - Out Parameter

C# provides out keyword to pass arguments as out-type. It is like reference-type, except that it does not require variable to initialize before passing. We must use out keyword to pass argument as out-type. It is useful when we want a function to return multiple values.

C# Out Parameter Example 1

1. using System;  
2. namespace OutParameter  
3. {  
4.     class Program  
5.     {  
6.         // User defined function  
7.         public void Show(out int val) // Out parameter  
8.         {  
9.             int square = 5;  
10.             val = square;  
11.             val *= val; // Manipulating value  
12.         }  
13.         // Main function, execution entry point of the program  
14.         static void Main(string[] args)  
15.         {  
16.             int val = 50;  
17.             Program program = new Program(); // Creating Object  
18.             Console.WriteLine("Value before passing out variable " + val);  
19.             program.Show(out val); // Passing out argument  
20.             Console.WriteLine("Value after recieving the out variable " + val);  
21.         }  
22.     }  
23. }  

Output:

Value before passing out variable 50
Value after receiving the out variable 25

The following example demonstrates that how a function can return multiple values.

C# Out Parameter Example 2

1. using System;  
2. namespace OutParameter  
3. {  
4.     class Program  
5.     {  
6.         // User defined function  
7.         public void Show(out int a, out int b) // Out parameter  
8.         {  
9.             int square = 5;  
10.             a = square;  
11.             b = square;  
12.             // Manipulating value  
13.             a *= a;   
14.             b *= b;  
15.         }  
16.         // Main function, execution entry point of the program  
17.         static void Main(string[] args)  
18.         {  
19.             int val1 = 50, val2 = 100;  
20.             Program program = new Program(); // Creating Object  
21.             Console.WriteLine("Value before passing \n val1 = " + val1+" \n val2 = "+val2);  
22.             program.Show(out val1, out val2); // Passing out argument  
23.             Console.WriteLine("Value after passing \n val1 = " + val1 + " \n val2 = " + val2);  
24.         }  
25.     }  
26. }  

Output:

Value before passing
 val1 = 50
 val2 = 100
Value after passing
 val1 = 25
 val2 = 25