Failing an input

[Duki]

Hey all, here is the part of my code I need help with:

#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    int acctNo, dayMin, nightMin, tmin;
    double amtDue;
    char serviceCode;

    cout << "Account Number:  " << flush;
    cin >> acctNo;

What I'm wanting to do is, if someone inputs anything other than an int, output an Invalide Service Code error... here is the rest of my code.

#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    int acctNo, dayMin, nightMin, tmin;
    double amtDue;
    char serviceCode;

    cout << "Account Number:  " << flush;
    cin >> acctNo;

    cout << "\nService Type:  " << flush;
    cin >> serviceCode;
    cout << endl;

    switch (serviceCode)
        case 'r': case 'R':
        {
        cout << "Please input total minutes used:  " << flush;
        cin >> tmin;

        amtDue = 10.00 + ( (tmin - 50) * 0.20 );

        cout << endl << fixed << showpoint << setprecision(2);
        cout << left << "Account:  " << acctNo << endl << endl;
        cout << setfill('.') << setw(25) << left << "Service Type: " << right << " Regular" << endl;
        cout << setfill('.') << setw(25) << left << "Total Minutes Used " << right << " " << tmin << endl;
        cout << setfill('.') << setw(25) << left << "Amount Due: " << right << " $" << amtDue << endl;
        break;

        case 'p': case 'P':

            cout << "Total Day Time Minutes (6:00am-6:00pm):  " << flush;
            cin >> dayMin;
            cout << "Total Night Time Minutes (6:00pm - 6:00am):  " << flush;
            cin >> nightMin;

            amtDue = 25.00 + ((dayMin - 75) * 0.10) + ((nightMin - 100) * 0.05);
            tmin = dayMin + nightMin;

            cout << endl << fixed << showpoint << setprecision(2);
            cout << left << "Account:  " << acctNo << endl << endl;
            cout << setfill('.') << setw(25) << left << "Service Type: " << right << " Premium" << endl;
            cout << setfill('.') << setw(25) << left << "Total Minutes Used " << right << " " << tmin << endl;
            cout << setfill('.') << setw(25) << left << "Amount Due: " << right << " $" << amtDue << endl;
            break;

        default: cout << "!! Invalid Service Code !!" << endl;
        }
}

If you look at line 51 you'll see something as to what I want to do, though I'm not sure how to do it.

I tried if (acctNo != int) .... but it gave an error of unexpected int.

Thanks for any help! :mrgreen:

[Duki]

oops, can someone delete the other thread? deffinately didn't mean to do that :(

[~s.o.s~]

A simplistic way with the minimalistic error checking would be:

#include <iostream>
#include <string>

int main ()
{
    using namespace std ;

    const char allowed_chars[] = "0123456789" ;
    string my_var ;
    int num  = 0 ;

    cout << "Enter the account number: " ;
    cin >> my_var ;
    getchar () ;

    if ( my_var.find_first_not_of (allowed_chars) != string::npos )
    {
        cout << "The thing you have entered is not a number" ;
    }
    else
    {
        num = atoi (my_var.c_str()) ;
        cout << "The number is " << num ;
    }

    getchar ( ) ;
    return 0 ;
}

The trick here is accepting the input as a string so that you would have more control over it and validating it according to your own business rules.

[Duki]

ah, ok... very clever.

only problem is, we haven't gone over any of this:
( my_var.find_first_not_of (allowed_chars) != string::npos )

[~s.o.s~]

Its just a simple function of the string class. The above statement means that if the variable my_var doesn't contains any one of the characters specified in the allowed_chars variable, it will return the index of that character.

More reference can be found here.

[Duki]

oh ok thanks!

[WaltP]

How about:
Read a string as ~sos~ suggests.
Convert the string to int
If it a valid value, use it, else output error