The Out Parameter with Example in C#

 The Out Parameter with Example in C#

In C#, out keyword is used to pass arguments to the method as a reference type. The out keyword same as the ref keyword but the only difference is out doesn’t require a variable to be initialized before we pass it as an argument to the method but the variable must be initialized in called method before it returns a value to the calling method. The out parameter in C# is also useful to return more than one value from methods.

Declaration of C# Out Parameter

Following is a simple example of using out parameters in C#.

 int x; // No need to initialize variable

OutParameterMultTest(out x);

 

From the above declaration, we just declared a variable x and pass it to the method by using out parameter without assigning any value but as discussed, the variable must be initialized in called method before it returns a value to the calling method.

                          

To use out parameter in C# application, both the method definition and the calling method must explicitly use the out keyword.

 

Out Parameter Example in C#

The following is an example of passing an out parameter to a method in C#.

 

using System;

namespace CsharpnaijaTutorial

{

    class Program

    {

        static void Main(string[] args)

        {

            int x;

            OutTestMult(out x);

            Console.WriteLine($"Variable Value: {x}");

            Console.WriteLine("Press Enter Key to Exit..");

            Console.ReadLine();

 

        }

        public static void OutTestMult (out int a)

        {

            a = 10;

            a *= a;

        }

    }

}

 

Examining the above example, we declared a variable x and passing it to a OutTestMult method by using out keyword without initializing the value. However, the called method (OutTestMult) is initializing the value before returning the value to the calling method. 

 

Multiple Out Parameters Example

The following is an example of using multiple out parameters in C#.

 

using System;

namespace CsharpnaijaTutorial

 

{

    class Program

    {

        static void Main(string[] args)

        {

            int x, y;

            OutTestMult(out x, out y);

            Console.WriteLine($"x Value: {x}");

            Console.WriteLine($"y Value: {y}");

            Console.WriteLine("Press Enter Key to Exit..");

            Console.ReadLine();

        }

        public static void OutTestMult(out int a, out int b)

        {

            a = 20;

            b = 15;

            a *= a;

            b *= b;

        }

    }

}

 

The output of the above code sample is as shown below

 The C# nigeria tutorial out parameter article

References

1.     Tutlane

2.     CsharpCorner

3.     MicrosoftDocumentation

4.     Geeksfor Geeks