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C#.Net find output programs (default Arguments) | set 2

Find the output of C#.Net programs | default Arguments | Set 2: Enhance the knowledge of C#.Net default Arguments concepts by solving and finding the output of some C#.Net programs.
Submitted by Nidhi, on February 07, 2021

Question 1:

using System;

namespace Demo
{
    class Program
    {
        static int ret()
        {
            return 10;
        }
        static void fun(int a, int b = 50, int c = ret())
        {
            Console.WriteLine("A: " + a + ", B: " + b + ", C: " + c);
        }

        //Entry point of the program
        static void Main(string[] args)
        {
            fun(10, 20, 40);
            fun(10, b: 20);
        }
    }
}

Output:

main.cs(11,52): error CS1736: The expression being assigned to 
optional parameter `c' must be a constant or default value

Explanation:

The above program will generate syntax error because we can use an only a compile-time constant for default arguments, we cannot use method call for default argument,

static void fun(int a, int b = 50, int c = ret())

In the above method definition, we called method ret(), which is not correct.

Question 2:

using System;

namespace Demo
{
    class Program
    {
        static void fun(int a, int b = 50, int c = sizeof(int))
        {
            Console.WriteLine("A: " + a + ", B: " + b + ", C: " + c);
        }

        //Entry point of the program
        static void Main(string[] args)
        {
            fun(10, 20, 40);
            fun(10, b: 20);
        }
    }
}

Output:

A: 10, B: 20, C: 40
A: 10, B: 20, C: 4
Press any key to continue . . .

Explanation:

In the above program, we create a class Program that contains two static methods fun() and Main() and here we used sizeof(int) that is 4, as a default value for argument c in fun() method.

The method fun() contains three arguments a, b, and c. Here, arguments b and c are used as default arguments. It means if we did not pass the values of 2^nd or 3^rd argument in the method fun(), then it takes use default values.

Now coming to the Main() method, this is an entry point for program execution,

fun(10, 20, 40);

The above method call will print "A: 10, B: 20, C: 40" on the console screen,

fun(10, b:20);

The above method call will print "A: 10, B: 20, C: 4" on the console screen. Here we used the default value of argument 'c'.

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