Endless loop when entering ch

Hi programmers.
When I choose a character instead of integer the program goes in endless loop how can I control this?
Thanks

Code:

---


// This program displays a menu and asks the user to make a
// selection. A do-while loop repeats the program until the
// user selects item 4 from the menu.
#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
  int choice;      // Menu choice
  int months;      // Number of months
  double charges;  // Monthly charges
 
  // Constants for membership rates
  const double ADULT = 40.0;
  const double SENIOR = 30.0;
  const double CHILD = 20.0;

  // Set up numeric output formatting.
  cout << fixed << showpoint << setprecision(2);
 
  do
  {
      // Display the menu.
      cout << "\n\t\tHealth Club Membership Menu\n\n";
      cout << "1. Standard Adult Membership\n";
      cout << "2. Child Membership\n";
      cout << "3. Senior Citizen Membership\n";
      cout << "4. Quit the Program\n\n";
      cout << "Enter your choice: ";
      cin >> choice;
     
      // Validate the menu selection.
      while (choice < 1 || choice > 4)
      {
        cout << "Please enter 1, 2, 3, or 4: ";
        cin >> choice;
      }

      // Validate and process the user's choice.
      if (choice != 4)
      {
        // Get the number of months.
        cout << "For how many months? ";
        cin >> months;
       
        // Respond to the user's menu selection.
        switch (choice)
        {
            case 1:  charges = months * ADULT;
                    break;
            case 2:  charges = months * CHILD;
                    break;
            case 3:  charges = months * SENIOR;
        }
       
        // Display the monthly charges.
        cout << "The total charges are $";
        cout << charges << endl;
      }
  } while (choice != 4);
  return 0;
}

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use a char instead of an int for the choice and test for '1', '2', '3', '4'
or use getline and one of those converter functions, i dont remember what they were called
here is an idea of the code to use

Code:

---


char choice[100];
do
{
      for(int a = 0; a < 100; a++)
              choice[a] = ' ';
          // the rest of your code
}
while(choice != '4')

---

this is not a solution for the problem... thanks any way

Hello ,

trying using isdigit(ch) to check if the entered value is a number. then proceed to checking the bounds.
Include ctypes.h in the header.. !!

cheers

Hello ,

trying using isdigit(ch) to check if the entered value is a number. then proceed to checking the bounds.
Include ctypes.h in the header.. !!

cheers

I may be missing something completely (always a disclaimer) but what happened to cin.clear, cin.ignore(100, '\n')? But...like I said. I could be missing something.

I just wrote some code to try to find out how can I control to much easily. I tried to use isdigit() and cin.clear but is not working. I have been looking for solution for hours. There have to be way to control the input. When I enter character instead of a number it still goes in infinity loop.

Code:

---

#include<iostream>

using namespace std;

int main()

{

int num, total=0;

        cout << "Enter int number";
        cin >> num;

while (num < 0)
        {
        cout << "Enter int number";
        cin >> num;
        }


        for( int i = 0; i <= num ;i++)
        total += i;
        cout << total;

return 0;
}

---

try..

this should work:

Code:

---


 while(getchar()!='\n') ;//put this year after initial initial input
 while (choice < 1 || choice > 4)
{
      {
        cout << "Please enter 1, 2, 3, or 4: ";
        while(getchar()!='\n') ;//and here
               
               
      }
        getchar() ;
}

---

Oh boy. First char arrays, now C code.
OK, first, don't use char arrays.
Secondly, don't use getchar to clear the input buffer. This cannot be guaranteed to work properly...
The most beginner friendly way of doing this is... read into a char. Yes. A char.
Then test with isdigit if that char is a number. If not, print an error, and redo it all.

char c;
cin >> c;
if (!isdigit(c)) cout << "Please enter a number!";
...

I usually wouldn't just post a corrected version of something that looks like an assignment, but this is a pretty trivial change. You can do comparisons with chars, so e.g. you can make choice a char and do:

Code:

---

while (choice < '1' || choice > '4')

---

Basically I've just made choice into a char, made it compare with other chars and put chars into your switch statement.

Code:

---

// This program displays a menu and asks the user to make a
// selection. A do-while loop repeats the program until the
// user selects item 4 from the menu.
#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
  char choice;      // Menu choice
  int months;      // Number of months
  double charges;  // Monthly charges
 
  // Constants for membership rates
  const double ADULT = 40.0;
  const double SENIOR = 30.0;
  const double CHILD = 20.0;

  // Set up numeric output formatting.
  cout << fixed << showpoint << setprecision(2);
 
  do
  {
      // Display the menu.
      cout << "\n\t\tHealth Club Membership Menu\n\n";
      cout << "1. Standard Adult Membership\n";
      cout << "2. Child Membership\n";
      cout << "3. Senior Citizen Membership\n";
      cout << "4. Quit the Program\n\n";
      cout << "Enter your choice: ";
      cin >> choice;
     
      // Validate the menu selection.
      while (choice < '1' || choice > '4')
      {
        cout << "Please enter 1, 2, 3, or 4: ";
        cin >> choice;
      }

      // Validate and process the user's choice.
      if (choice != '4')
      {
        // Get the number of months.
        cout << "For how many months? ";
        cin >> months;
       
        // Respond to the user's menu selection.
        switch (choice)
        {
            case '1':  charges = months * ADULT;
                    break;
            case '2':  charges = months * CHILD;
                    break;
            case '3':  charges = months * SENIOR;
        }
       
        // Display the monthly charges.
        cout << "The total charges are $";
        cout << charges << endl;
      }
  } while (choice != '4');
  return 0;
}

---

Thanks Mozza314, this is not assignment. I am reading a book and try to teach myself (starting out with c++ from control structures trough objects) .The way of replacing all choice with '1' as ch var, I get it and it works. But what about if you want to make calculations as svetlin’s example.
I tried what Elysia suggested and it works but still assigns the var to a char. What if I want to use that variable for calculations?

Quote:

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Originally Posted by sid13

I tried what Elysia suggested and it works but still assigns the var to a char. What if I want to use that variable for calculations?

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Declare another variable.