Functions

1. A Simple program without using functions

    Code Listing: 

// Purpose: This program find the absolute value of an integer
// without using a function


#include <iostream>
using namespace std;

int main()
{
int number;
int abs_number;

// Ask for input
cout << "This program finds the absolute value of an integer." << endl;
cout << "Enter an integer (positive or negative): ";
cin >> number;

// Find the absolute value
if(number >= 0)
{
abs_number = number;
}
else
abs_number = -number;

// Print out output
cout << "The absolute value of " << number << " is " << abs_number;
cout << endl;
return 0;
}

    Running session:

This program finds the absolute value of an integer.
Enter an integer (positive or negative): -45
The absolute value of -45 is 45

This program finds the absolute value of an integer.
Enter an integer (positive or negative): 0
The absolute value of 0 is 0

This program finds the absolute value of an integer.
Enter an integer (positive or negative): 9
The absolute value of 9 is 9
 

2. The same program using function

Code listing:

// Purpose: This program finds the absolute value of an integer
// using a function


int Abs(int i); // Function prototype
int main()
{
int number;
int abs_number;

cout << "This program finds the absolute value of an integer." << endl;
cout << "Enter an integer (positive or negative): ";
cin >> number;

// Calling the function Abs()
abs_number = Abs(number);
cout << "The absolute value of " << number << " is " << abs_number;
cout << endl;
return 0;
}
// Function definition
int Abs(int i)
{
if( i >= 0)
return i;
else
return -i;
}

Running session:

This program finds the absolute value of an integer.
Enter an integer (positive or negative): -45
The absolute value of -45 is 45

This program finds the absolute value of an integer.
Enter an integer (positive or negative): 0
The absolute value of 0 is 0

This program finds the absolute value of an integer.
Enter an integer (positive or negative): -9
The absolute value of -9 is 9