Can anyone figure out why my loops are falling through? - c++

Question

this is my first post here. I am new to c++ (just started last week) and have spent a few hours on this and am stumped.
I am aware that I am probably doing many things wrong in this program, but I assure you all I have tried my best. Validating inputs is beyond the scope of my homework, but I wanted to try it out since just getting inputs and returning them is boring.
Basically, the input validation works for the outer loop, but with the inner loops it will fall through even if invalid.
#include <iostream>
using namespace std;
//Global Variables
int cubeLength = 0;
int cubeWidth = 0;
int cubeHeight = 0;
int cubeSurfaceArea = 0;
int cubeVolume = 0;
bool valid = false;
int main() {
//Ask user for cubeLength and validate input for integer values
do {
cout << "Please enter a numerical value for the length of a cube" <<endl;
cin >> cubeLength;
if (cin.good()) {
valid = true;
//Ask user for cubeWidth and validate input for integer values
do {
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (cin.good()) {
valid = true;
//Ask user for cubeHeight and validate input for integer values
do {
cout << "Please enter a numerical value for the height of a cube" <<endl;
cin >> cubeHeight;
if (cin.good()) {
valid = true;
}
else
{
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube height. Please try again" << endl;
}
}while (!valid);
}
else
{
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube width. Please try again" << endl;
}
}while (!valid);
}
else
{
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube length. Input is not an integer" << endl;
}
} while (!valid);
//Perform calculations for surface area and volume then assign them to their associated variables
if (cubeLength >= 1 && cubeWidth >= 1 && cubeHeight >= 1)
{
valid = true;
cubeSurfaceArea = ((2*(cubeWidth*cubeLength))+(2*(cubeLength*cubeHeight))+(2*(cubeWidth*cubeHeight)));
cubeVolume = (cubeWidth*cubeLength*cubeHeight);
}
else {
cout << "Sorry, one or more cube inputs is invalid. Ending program. Please restart and try again." << endl;
return 0;
}
//Output surface area and volume to user
cout << "Length = " << cubeLength << " Width = " << cubeWidth << " Height = " << cubeHeight << endl;
cout << "The surface area of your cube is " << cubeSurfaceArea << "." << endl;
cout << "The volume of your cube is " << cubeVolume << "." << endl;
//Pause system and end program
return 0;
}
I added the if statement for the calculations at the bottom to stop this from falling all of the way through the program and exit.
I have also checked a lot of similar questions on validating inputs for integers and loops on this site and others, but haven't been able to figure it out. My theory is that i'm either messing up the boolean logic for valid, or using the wrong looping method.

Answer 1

The main problem with the loops is that you are setting valid to true but never to false, so the statement while (!valid) will never evaluate to false.
Another general comment is that the layout of the code has too many nested loops. This can be simplified a lot.
I did not test the code below, but this type of structure is much easier to read - ie doing each input separately, rather than jumbling the all together! :-)
//Ask user for cubeLength and validate input for integer values
valid = true;
do {
cout << "Please enter a numerical value for the length of a cube" <<endl;
cin >> cubeLength;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube length. Input is not an integer" << endl;
}
} while (!valid);
//Ask user for cubeWidth and validate input for integer values
do {
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube width. Please try again" << endl;
}
} while (!valid);
//Ask user for cubeHeight and validate input for integer values
do {
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube height. Please try again" << endl;
}
}while (!valid);

Answer 2

After the first time you set valid = true, it stays true till the end. You should take it back to false before testing it again.

Answer 3

Thank you to everyone who provided help and feedback:
The issue is painfully obvious to me now, which is the boolean value not being reset at the beginning of the loop after a failed validation on input.
I redid the entire code per suggestions and have a stable program now!:)
#include <iostream>
using namespace std;
//Global Variables
int cubeLength = 0;
int cubeWidth = 0;
int cubeHeight = 0;
int cubeSurfaceArea = 0;
int cubeVolume = 0;
bool valid = true;
char choice;
int main() {
do {
//Ask user for cubeLength and validate input for integer values
do {
valid = true;
cout << "Please enter a numerical value for the length of a cube" <<endl;
cin >> cubeLength;
if (cin.fail()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube length. Input is not an integer" << endl;
}
} while (!valid);
//Ask user for cubeWidth and validate input for integer values
do {
valid = true;
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (cin.fail()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube width. Input is not an integer" << endl;
}
} while (!valid);
//Ask user for cubeHeight and validate input for integer values
do {
valid = true;
cout << "Please enter a numerical value for the height of a cube" <<endl;
cin >> cubeHeight;
if (cin.fail()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, '\n');
cout << "Invalid cube height. Input is not an integer" << endl;
}
}while (!valid);
//Perform calculations for surface area and volume then assign them to their associated variables
if (cubeLength >= 1 && cubeWidth >= 1 && cubeHeight >= 1)
{
cubeSurfaceArea = ((2*(cubeWidth*cubeLength))+(2*(cubeLength*cubeHeight))+(2*(cubeWidth*cubeHeight)));
cubeVolume = (cubeWidth*cubeLength*cubeHeight);
}
else {
cout << "Sorry, one or more cube inputs is invalid. Ending program. Please restart and try again." << endl;
return 0;
}
//Output surface area and volume to user
cout << "Length = " << cubeLength << " Width = " << cubeWidth << " Height = " << cubeHeight << endl;
cout << "The surface area of your cube is " << cubeSurfaceArea << "." << endl;
cout << "The volume of your cube is " << cubeVolume << "." << endl;
cout << "Would you like to try again? (y/n)" << endl;
cin >> choice;
} while (choice != 'n');
//Pause system and end program
return 0;
}