how to exclude character input

the program i wrote: it works alright if i input a number, but any mist ake to input a letter, it will cause the program run infinitely. Any comment or help to fix the problem will be very appreciated.


#include <iostream.h>
int main ()
{
double premium, discounted;
int age, accident, units;
do
{
cout << "Enter your age:" ;
cin >> age;
if ( age <= o)
cout << " error input, try again : " ;
} while ( age <= 0 ) ;


cout << "Enter accident if you had in the past, (yes = 1 and no = 0): " ;
cin >> accident ;
cout << "Enter number of units if you are a student ; if not, enter 0: " ;
cin >> units;

if ( age >= 26 && accident > 0 && units >= 12 )
premium = 80 - ( 80*0.05 ), discounted = ( 80*0.05 ) ;

else if ( age >=26 && accident <= 0 && units >= 12 )
premium = 80 - ( 80*0.05 + 80*0.10 ), discounted = ( 80*0.05 + 80*0.10 ) ;

else if ( age >=26 && accident <= 0 && units < 12 )

premium = 80 - ( 80*0.10 ), discounted = ( 80*0.10 ) ;

else if ( age >=26 && accident > 0 && units < 12 )

premium = 80, discounted = 0 ;
else if ( (age < 26 && age >= 18 ) && accident > 0 && units >= 12 )

premium = 100 - ( 100*0.05 ), discounted = ( 100*0.05 ) ;

else if ( ( age < 26 && age >= 18 ) && accident <= 0 && units >= 12 )

premium = 100 - ( 100*0.15 ), discounted = ( 100*0.15 ) ;

else if ( ( age < 26 && age >= 18 ) && accident <= 0 && units < 12 )

premium = 100 - ( 100*0.10 ), discounted = ( 100*0.10 ) ;

else if ( ( age < 26 && age >= 18 ) && accident > 0 && units < 12 )

premium = 100, discounted = 0 ;

else if ( age < 18 && accident > 0 && units >= 12 )

premium = 150 - ( 150*0.05 ), discounted = ( 150*0.05 ) ;

else if ( age < 18 && accident <= 0 && units >= 12 )

premium = 150 - ( 150*0.15 ), discounted = ( 150*0.15 ) ;

else if ( age < 18 && accident <= 0 && units < 12 )

premium = 150 - ( 150*0.10 ), discounted = ( 150*0.10 ) ;

else if ( age < 18 && accident > 0 && units < 12 )

premium = 150, discounted = 0 ;

cout << "discounted :" << discounted << endl;

cout << "premium : " << premium << endl;
return 0;
}

try looking up the isdigit() function.

Quote:

---

if ( age <= o)
cout << " error input, try again : " ;
} while ( age <= 0 ) ;

---

You made a typo there.
Also
You can do:

while (cin.fail())
{
cout << "Input Error!\n";
cin >> age;
}

-or-

while (!(cin >> age))
{
cout << "Input Error!\n";
cin >> age;
}

To catch input errors..
I'm not sure about the second, it might just be while (cin >> age)

hello

I try to fix but have no success because I am a beginer. Any more help? this is a lab excercise, I already get grade for it, instructor said it's ok for now, but I want to find out the "bug"/

thank

If your variable isn't a char type then you can use a conditional to check the success of cin.

Code:

---

int var;
if ( cin>>var )
  // It worked, var is an int
else
  // Error, user entered a char

or

while ( cin>>var ) {
  // Do your processing

---

-Prelude