Validation While Loop Only Repeating Every Other Time - c++

Question

I'm creating a program that is an arithmetic quiz. The program displays a menu and presents a quiz depending on the option that the user chooses (1 for addition, 2 for subtraction, etc.).
My while loops that validate if the user answered a problem correctly or incorrectly seems to be repeating every other time as opposed to every time. This ends up affecting the correct/incorrect counters for how many questions a user answers correctly/incorrectly, and I haven't been able to figure out why this is happening - what do I need to fix?
I am also having issues where the loop doesn't end even if the user enters -1 to stop.
#include <cstdlib>
#include <ctime>
using namespace std;
// function prototypes
void showMenu();
int add(int, int);
// main function
int main()
{
int choice = 0, answer = 0; // user input
int num1, num2; // numbers for problem
int correct_sum; // correct answer
int correct = 0, incorrect = 0; // counters
do
{
// display program purpose to user
cout << "********* Welcome to the Arithmetic Quiz *******\n";
cout << '\n';
// call showMenu function
showMenu();
cin >> choice; // user inputs menu choice
cout << '\n';
// switch statement for menu choice
switch (choice)
{
// addition
case 1:
do {
// randomize numbers
srand(time(NULL)); // random seed
num1 = rand() % 9 + 1; // random num1
num2 = rand() % 9 + 1; // random num2
// display problem to user
cout << "How much is " << num1 << " plus " << num2 << "?\n";
cout << "Enter your answer (-1 to return to the menu)\n";
cin >> answer;
cout << '\n';
// correct sum formula & call addition() function
correct_sum = add(num1, num2);
// while user's answer is WRONG and not -1
while (answer != correct_sum && answer != -1)
{
// display incorrect message
cout << "No. Please try again.\n";
incorrect++; // increment incorrect counter
// ask user for input again
cout << "Enter your answer (-1 to return to the menu)\n";
cin >> answer;
cout << '\n';
}
// while user's answer is RIGHT
while (answer == correct_sum)
{
// display correct message
cout << "Very Good!\n";
correct++; // increment correct counter
// randomize numbers again for different problem
srand(time(NULL)); // random seed
num1 = rand() % 9 + 1; // random num1
num2 = rand() % 9 + 1; // random num2
// show more problems to user until -1 is entered
cout << "How much is " << num1 << " plus " << num2 << "?\n";
cout << "Enter your answer (-1 to return to the menu)\n";
cin >> answer;
cout << '\n';
}
} while (answer != -1);
if (answer == -1)
{
// display addition results when answer == STOP
cout << "********* RESULTS *******\n";
cout << '\n';
cout << "Addition problems solved: " << (correct + incorrect) << '\n';
cout << "Number answered correctly: " << correct << '\n';
cout << "Number answered incorrectly: " << incorrect << '\n';
}
}
// --------------------------------------------------------------------------------------
// showMenu function
void showMenu()
{
// display menu options
cout << "MENU:\n";
cout << '\n';
cout << "1. Enter 1 for Addition\n";
cout << "2. Enter 2 for Subtraction\n";
cout << "3. Enter 3 for Multiplication\n";
cout << "4. Enter 4 for Division\n";
cout << "5. Enter 5 for Modulus\n";
cout << "6. Enter 6 to Exit\n";
cout << '\n';
}
// --------------------------------------------------------------------------------------
// add function
int add(int num1, int num2)
{
return (num1 + num2);
}

Answer 1

You don't have yo use while loop inside do..while loop, if condition will work there, Try below code i have commented some part of code.
#include<iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
// function prototypes
void showMenu();
int add(int, int);
// showMenu function
void showMenu()
{
// display menu options
cout << "MENU:\n";
cout << '\n';
cout << "1. Enter 1 for Addition\n";
cout << "2. Enter 2 for Subtraction\n";
cout << "3. Enter 3 for Multiplication\n";
cout << "4. Enter 4 for Division\n";
cout << "5. Enter 5 for Modulus\n";
cout << "6. Enter 6 to Exit\n";
cout << '\n';
}
// --------------------------------------------------------------------------------------
// add function
int add(int num1, int num2)
{
return (num1 + num2);
}
// main function
int main()
{
int choice = 0, answer = 0; // user input
int num1, num2; // numbers for problem
int correct_sum; // correct answer
int correct = 0, incorrect = 0; // counters
do
{
// display program purpose to user
cout << "********* Welcome to the Arithmetic Quiz *******\n";
cout << '\n';
// call showMenu function
showMenu();
cin >> choice; // user inputs menu choice
cout << '\n';
// switch statement for menu choice
switch (choice)
{
// addition
case 1:
do {
// randomize numbers
// srand(time(NULL)); // random seed
num1 = rand() % 9 + 1; // random num1
num2 = rand() % 9 + 1; // random num2
// display problem to user
cout << "How much is " << num1 << " plus " << num2 << "?\n";
cout << "Enter your answer (-1 to return to the menu)\n";
cin >> answer;
cout << '\n';
// correct sum formula & call addition() function
correct_sum = add(num1, num2);
// while user's answer is WRONG and not -1
while(answer != correct_sum && answer != -1)
{
// display incorrect message
cout << "No. Please try again.\n";
incorrect++; // increment incorrect counter
// ask user for input again
cout << "Enter your answer (-1 to return to the menu)\n";
cin >> answer;
correct_sum = add(num1, num2);
cout << '\n';
}
// while user's answer is RIGHT
if (answer == correct_sum)
{
// display correct message
cout << "Very Good!\n";
correct++; // increment correct counter
// randomize numbers again for different problem
// srand(time(NULL)); // random seed
num1 = rand() % 9 + 1; // random num1
num2 = rand() % 9 + 1; // random num2
// show more problems to user until -1 is entered
//cout << "How much is " << num1 << " plus " << num2 << "?\n";
//cout << "Enter your answer (-1 to return to the menu)\n";
//cin >> answer;
cout << '\n';
}
} while (answer != -1);
if (answer == -1)
{
// display addition results when answer == STOP
cout << "********* RESULTS *******\n";
cout << '\n';
cout << "Addition problems solved: " << (correct + incorrect) << '\n';
cout << "Number answered correctly: " << correct << '\n';
cout << "Number answered incorrectly: " << incorrect << '\n';
}
}
}while (answer != -1);
}
// --------------------------------------------------------------------------------------
Output of above code now if answer is not correct
********* Welcome to the Arithmetic Quiz *******
MENU:
1. Enter 1 for Addition
2. Enter 2 for Subtraction
3. Enter 3 for Multiplication
4. Enter 4 for Division
5. Enter 5 for Modulus
6. Enter 6 to Exit
1
How much is 6 plus 9?
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
No. Please try again.
Enter your answer (-1 to return to the menu)
10
I hope you are expecting this.