Question

The following code is inside a do while loop. choice is supposed to be an integer input by the user. However, when a character is put instead of an integer, the code loops infinitely. Putting break; or exit(); after the catch statements terminates the whole program, which is wrong. How can i fix this?

#include <iostream>

#include <vector>

#include <iomanip>

#include<stdlib.h>

#include <cctype>

#include "MyGrades.h"

using namespace std;

int main ()

{

   int choice; // user input for menu selection

   double quiz, program, test; // user input for grades

   MyGrades a; // class declaration

   cout << fixed << setprecision(2);

   cout << "Welcome to My Grades APP. " << endl;  

   do {

       cout << "\nMain Menu" << endl << endl;

       cout << " 1. Set A quiz Grade" << endl

          << " 2. Set A Programming Assignment Grade" << endl

   << " 3. Set A Test Grade" << endl

          << " 4. Show All quiz Grades" << endl

          << " 5. Show All Programming Assignment Grades" << endl

          << " 6. Show All Test Grades" << endl

          << " 7. Show Overall Grades" << endl

          << " 9. Exit The Program" << endl << endl;

      

       cout << "Enter your choice ---> ";

       cin >> choice;

       try {

           if (!isdigit(choice))

               throw choice;

       } catch (char choice) {

       cout << "Error *** Incorrect input - You entered a character" << endl;

           cout << "Enter a Positive Integer" << endl << endl;

       }

  

           switch(choice)

           {

               case 1: cout << "\nEnter Quiz grade: ";

       cin >> quiz;

       a.setQuiz(quiz);

                   break;

               case 2: cout << "\nEnter A Programming Assignment grade: ";

       cin >> program;

       a.setProgram(program);

                   break;

               case 3: cout << "\nEnter A Test grade: ";

       cin >> test;

       a.setTest(test);

                   break;

               case 4: cout << "\nShow All Quiz grades with Average." << endl;

       a.getQuiz();

                   break;

               case 5: cout << "\nShow All Programming Assignment grades with Average" << endl;

       a.getProgram();

                   break;

               case 6: cout << "\nShow all Test Grades with Average" << endl;

       a.getTest();

           break;

               case 7: cout << "\nShow Overall Grades." << endl;

       a.showAll();

                   break;

               case 9:

                   break;

               default:

       cout << "\nInvalid Choice" << endl;

                   break;

           }

      

   } while (choice != 9);

   cout << "\nImplemented by Emily Leyendecker and Maxwell Yi" << endl

   << "February - 2017" << endl << endl;

   return 0;

}

Answer 1

Answer:

goto for keep the program alive even in case of a non int input and the 2nd one is the solution of infinite loop .Here is the fixed code :

#include<iostream>

#include<cstdlib>
#include<fstream>
#include<cmath>

using namespace std;
int main()
{
   int a[30];
   int s;
   fstream file;
   int sum=0;
   int q=0;
   double averge;
   double st;
   int standard_deviation;
   int avg;
   int square;
   cout<<"\t How many person's tempurature you wanna save ";
   cin>>s;
   int temp=0;
   for(int i=0;i<s;i++)
   {
   a[i]=rand()%100;
     
   }
   cout<<"\t \t YOUR DATA HAS been saved in a file check file for results..."<<endl;
   file.open("temps.txt",ios::out|ios::app|ios::in);
  
       for(int i=0;i<s;i++)
       {
           file<<a[i]<<endl;
           sum=sum+a[i];
           avg=sum/s;
          
          
           st=avg-a[i];
           int s=-1*(st);
           square=s*s;
           temp=temp+square;
           temp=temp/s;
           standard_deviation=sqrt(temp);
          
          
       }
       file<<"Mean ="<<avg<<endl;
   file<<"standard deviation ="<<standard_deviation<<endl;
   file.close();
  
}