Question

In the code (C++) below, if you input 2 as length and 4 as width, the output is:

Enter the rectangle's length: 2

Enter the rectangle's width: 4

Length: 2 | Width: 4 | Area: 8 | Perimeter:12

We worked on this code during class, but there were some things that I did not understand.

1) how does compiler read"l" as length, "w" as width, etc.? I thought you had to update it first, like "w=width."

2) i thought you had to write "return 0" after every program. why in this code it is "return width," etc?

The code:

#include <iostream>

using namespace std;

double getLength();

double getWidth();

double getArea(double&, double&);

double getPerimeter(double&, double&);

void displayData(double&, double&, double&, double&);

// ***********************************************************//

int main() {

double length,

width,

area,

perimeter;

length = getLength();

width = getWidth();

area = getArea(length, width);

perimeter = getPerimeter(length, width);

displayData(length, width, area, perimeter);

return 0;

}

// ***********************************************************//

double getLength() {

double length;

cout << "Enter the rectangle's length: ";

cin >> length;

return length;

}

// ***********************************************************//

double getWidth() {

double width;

cout << "Enter the rectangle's width: ";

cin >> width;

return width;

}

// ***********************************************************//

double getArea(double& l, double& w) {

return l * w;

}

// ***********************************************************//

double getPerimeter(double& l, double& w) {

return 2 * (l + w);

}

// ***********************************************************//

void displayData(double& l, double& w, double& a, double& p) {

cout << "Length: " << l << " | Width: " << w << " | Area: " << a << " | Perimeter:" << p << '\n';

}

Answer 1

When you use cin>>length or cin>>width then Whatever comes from the keyboard is stored in a buffer. When you press enter the system passes the buffer to the application code (std::cin code). Operator >> will decide how much to read from that buffer - one char, string, int, float etc. Depends on the type of the operand.

Then you have function that return type is double for length and width so you have to return something as double , And in the function you have input the length and width by cin>>length and cin>>width which will be saved in corresponding variable length and width the the value saved in length and width will be returned by function..

And when you call the function it will give you the value of length and width as you calling in main() function...

then passing those value into other functions so you will get area and perimeter

and for main function you will return 0 because main function return type is int but returning nothing so you will return 0

Thanks a lot, Please let me know if you have any problem...................