Default Arguments in C++ Function

Definition

The default argument is an assigned value in the function declaration. That value will be assigned by the compiler when function call doesn’t have that argument.

Syntax

return_type function_name( param_1,param_2 = value )
for example,
int fn_multipy(int x, int y = 1);

Default Arguments in Function Example Program

//Simple Default Argument Function Example Program in C++
//Function Example

#include<iostream>
#include<conio.h>

using namespace std;

int fn_multipy(int x, int y = 1);

int main() {
   int a = 200, b = 100;
   cout << "Simple Default Argument Function Example Program\n";

   cout << "\nWorks for a and b    :" << fn_multipy(a, b);
   cout << "\nWorks for a          :" << fn_multipy(a);

   getch();
}

// Default Argument Function

int fn_multipy(int x, int y) {
   return (x * y);
}

Sample Output

Simple Default Argument Function Example Program

Works for a and b    :20000
Works for a          :200

How It Works

This C++ program demonstrates Default Arguments in Function. It first prepares the data it needs, then performs the core operation step by step, and finally prints the output shown in the Sample Output above.

1. Declare the variables that hold the program’s data.
2. Print the final result to the console so you can compare it with the sample output.

Try changing the input values and re-running the program to see how the output changes — this is the fastest way to understand how the logic behaves.

Related Pages

Continue learning with these related tutorials and programs:

• C++ Tutorials — Browse all C++ Tutorials.
• C++ Function Basics — Tutorial — function syntax and calling conventions.
• Function Prototyping In C++ — More in functions in c.
• Function Types in C++ — More in functions in c.