Quick C++ Question On Boundaries - Topic

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Sep 15 2013 12:04pm

I wrote a code for calculating perimeter and area of a rectangle. If I wanted the input to only accept positive integer values, how/where would I put that in my code?

Code

#include <iostream>
using namespace std;

int main()
{
int length = 0;
int width = 0;
int perimeter = length + length + width + width;
int area = length * width;

cout << "Enter length of rectangle: ";
cin >> length;
cout << "Enter width of rectangle: ";
cin >> width;
perimeter = length + length + width + width;

cout << "The perimeter of the rectangle is: " << perimeter <<endl;

area = length * width;

cout << "The area of the rectangle is: " << area<< endl;

system("pause");
return 0;
}

This post was edited by King3r on Sep 15 2013 12:05pm

carteblanche

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Sep 15 2013 12:16pm

1) accept strings instead of ints
2) immediately cast to int. if fails, bitch at user
3) immediately check > 0. if fails, bitch at user

labatymo

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Sep 15 2013 01:47pm

while(true){
cout << "Enter length of rectangle: ";
cin >> length;
cout << "Enter width of rectangle: ";
cin >> width;

if (!(length <0) || !(width < 0)){
break;
}
cout << "Invalid input";
}

perimeter = length + length + width + width;

cout << "The perimeter of the rectangle is: " << perimeter <<endl;

area = length * width;

cout << "The area of the rectangle is: " << area<< endl;

system("pause");
return 0;

NeX_1337

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Sep 30 2013 06:00am

While loop for when users enters a number smaller than 0.

like
while (x<0 || y<0){
if(x<0) {
cout << "Invalid length, please enter a positive number: ";
cin >> x;
}
if(y<0){
cout << "Invalid width, please enter a positive number: ";
cin >> y;
}

You might also want to use doubles rather than integers since length doesn't have to be an integer.

ogelami

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Oct 1 2013 06:40am

You could either check the value using an if statement, or you can use the http://www.cplusplus.com/reference/cstdlib/abs/ function, third option would to use types that does not support negative values such as unsigned int or unsigned short.
And you are aware that your code makes perimeter = 0 + 0 + 0 + 0 and area 0 * 0 and then setting them, if they are supposed to be 0 there why dont you skip the arithmetic operations?

Code

int perimeter = length + length + width + width;
int area = length * width;

Code

int perimeter;
int area;

0n35

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Oct 2 2013 01:01am

Quote (carteblanche @ Sep 15 2013 01:16pm)

1) accept strings instead of ints
2) immediately cast to int. if fails, bitch at user
3) immediately check > 0. if fails, bitch at user

in every program you ever do that involves numbers, do this

ligs

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Oct 2 2013 09:30pm

You can use unsigned integers
You can test the value in a loop
You can test the value in a conditional
You can throw an exception and make the user correct their input
Etc...
There are various paths to the solution of most problems.

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