"For loop" continues without prompting.

[larxi]

Dear C++ users,

I am reading DEITEL's book about C++ and experimenting with the examples.
(For those who may own the book I am talking about fig06_11.cpp)

So here is the code (modified)

#include <iostream>

using std::cout;
using std::cin;
using std::endl;
using std::fixed;

#include <iomanip>

#include "salesp.h"

// initialize elements of array sales to 0.0
SalesPerson::SalesPerson()
{
   for ( int i = 0; i < 12; i++ )
      sales[ i ] = 0.0;

} // end SalesPerson constructor

// get 12 sales figures from the user at the keyboard
void SalesPerson::getSalesFromUser()
{
   double salesFigure;

   for ( int i = 1; i <= 12; i++ ) {
      cout << "Enter sales amount for month " << i << ": ";
      cin >> salesFigure;
      setSales( i, salesFigure );

   } // end for

} // end function getSalesFromUser

// set one of the 12 monthly sales figures; function subtracts
// one from month value for proper subscript in sales array
int SalesPerson::setSales( int month, double amount )
{
 cout << amount << endl;
   // test for valid month and amount values
   if ( month >= 1 && month <= 12 && amount > 0 )
      sales[ month - 1 ] = amount; // adjust for subscripts 0-11

   else // invalid month or amount value
      cout << "Invalid month or sales figure" << endl;

} // end function setSales 

The header file:

class SalesPerson {

public:
   SalesPerson();                // constructor
   void getSalesFromUser();      // input sales from keyboard
   int setSales( int, double ); // set sales for a month
  
private:
   double sales[ 12 ];           // 12 monthly sales figures

}; 

Now if we run:

#include "salesp.h"
using namespace std;

int main()
{
   SalesPerson s;         // create SalesPerson object s

   s.getSalesFromUser();  // note simple sequential code; no
  
   return 0;

} 

If I enter a character,which is worng, the loop continious without prompting me to enter any number. Why is that?
I can't understand why it continious. I don't check to see what the user enters in the code but when I am trying to sign a char to a double, wouldn't the for "break" or continue prompting me to enter data?

Enter sales amount for month 1: k
Invalid month or sales figure
Enter sales amount for month 2: Invalid month or sales figure
Enter sales amount for month 3: Invalid month or sales figure
Enter sales amount for month 4: Invalid month or sales figure
Enter sales amount for month 5: Invalid month or sales figure
Enter sales amount for month 6: Invalid month or sales figure
Enter sales amount for month 7: Invalid month or sales figure
Enter sales amount for month 8: Invalid month or sales figure
Enter sales amount for month 9: Invalid month or sales figure
Enter sales amount for month 10: Invalid month or sales figure
Enter sales amount for month 11: Invalid month or sales figure
Enter sales amount for month 12: Invalid month or sales figure

Process returned 0 (0x0)   execution time : 2.583 s

Thank you for your time! :-)

[kooth]

Your code looks good to me. After you type in the letter "k", cin probably needs to have its error bit cleared.

[larxi]

Thank you for your reply kooth. Could you please explain to me what do you mean when you say "its error bit cleared"?

Thank you gain for your time. :-)

[kooth]

When you get the error, try this in your code:

cin.clear();

[larxi]

I tried that, but the loop continues without prompting. Nothing happened.

cin.fail() is true though...

[kooth]

Can you post the section of code where you put the clear?

[larxi]

int SalesPerson::setSales( int month, double amount )
{

   // test for valid month and amount values
   if ( month >= 1 && month <= 12 && amount > 0 )
      sales[ month - 1 ] = amount; // adjust for subscripts 0-11

   else { // invalid month or amount value
      cout << "Invalid month or sales figure" << endl;
      cin.clear();
    }
} 

[kooth]

Do the check right after you read input, something like this:

if( cin.fail() )
    {
    cin.clear();

     cin.ignore( std::numeric_limits<int>::max(), '\n' );

    }    /*    if( cin.fail() )    */

This will reset cin.

[larxi]

kooth thank you very much! It worked!!

Because I am a newbie can you explain to me why cin.clear() by itself doesnt work??


Thank you again for your time!! :-)

[kooth]

It is because cin loses its integrity when it handles the wrong input type. Keep searching for better ways to get input from the user. There are many great examples on this Website.