Question

I want the do while loop to check to see if the entered input is R OR P. I think it is checking for both and when I get to that part when I run, it pauses for a minute and then I get "CPU Limit Exceeded (core dumped). On another related note, am I in danger of breaking something?

/************************************************/
/* Name: servcode                               */
/* Description: Get service type                */
/* Parameters: N/A                              */
/* Return Value: servcode                       */
/************************************************/

char servcode()
{
  char servcode = 'a';   // Define variable for service code
  char serviceyn = 'n';  // Define variable for user verify
  int i = 1;             // Define variable for sentinel loop

  do {
    cout << "\n" << "\n" << "Please enter your service code, [R]egular or [P]remium: " << "\n";
    cin >> servcode;
    while ((servcode != 'R', 'P') && (i < 3));
    {
        cout << "\n" << "Error - invalid service code, please try again.";
        cout << "\n" << "Please enter your service code: ";
        cin >> servcode;
        i++;
        if (i == 3)
        {
            cout << "\n" << "Too many invalid attempts, program terminating." << "\n"
             << "Have a nice day. " << "\n" << "\n";
            exit (0);
        } //end if
    } //end while
    cout << "\n" << "You entered: " << servcode << "\n"
     << "Is that correct? [y,n]";
    cin >> serviceyn;
  } while (serviceyn != 'y'); // end do/while loop

  return servcode;
}

Answer 1

The correct syntax is:

while (servcode != 'R' && servcode != 'P' && i < 3)

Note the expanded comparison and the removal of the semicolon at the end:

1. (servcode != 'R', 'P') is valid C++ but doesn’t do what you’re expecting it to do;
2. the semicolon makes the statement into a loop with an empty body, so it continues executing forever since the loop condition never changes.