Mathematics errors in basic C++ program

Question

I am working with a basic C++ program to determine the area and perimeter of a rectangle. My program works fine for whole numbers but falls apart when I use any number with a decimal. I get the impression that I am leaving something out, but since I'm a complete beginner, I have no idea what.

Below is the source:

#include <iostream>

using namespace std;

int main()
{
    // Declared variables
int length;  // declares variable for length
int width;  // declares variable for width
int area;  // declares variable for area
int perimeter; // declares variable for perimeter


    // Statements
cout << "Enter the length and the width of the rectangle: ";  // states what information to enter
cin >> length >> width;  // user input of length and width
cout << endl;  // closes the input
area = length * width;  // calculates area of rectangle
perimeter = 2 * (length + width);  //calculates perimeter of rectangle
cout << "The area of the rectangle = " << area << " square units." <<endl;  // displays the calculation of the area
cout << "The perimeter of the rectangle = " << perimeter << " units." << endl;  // displays the calculation of the perimeter
system ("pause"); // REMOVE BEFORE RELEASE - testing purposes only

return 0;
}

Answer 1

Change all your int type variables to double or float. I would personally use double because they have more precision than float types.

Answer 2

use floats not ints an integer (int) is a whole number, floats allow decimal places (as do doubles)

float length;  // declares variable for length
float width;  // declares variable for width
float area;  // declares variable for area
float perimeter; // declares variable for perimete

Answer 3

You've defined your variables as integers. Use double instead.

Also, you can look up some formatting for cout to define the number of decimal places you want to show, etc.

Answer 4

int datatype stands for integer (i.e. positive and negative whole numbers, including 0)

If you want to represent decimal numbers, you will need to use float.

Answer 5

Thanks, everyone. I knew it would be something simple. Just not that simple.

Answer 6

Use the float or double type, like the others already said.

But it ain't as simple as that. You need to understand what floating-point numbers actually are, and why (0.1 + 0.1 + 0.1) != (0.3). This is a complicated subject, so I won't even try to explain it here - just remember that a float is not a decimal, even if the computer is showing it to you in the form of a decimal.