[Dev-C++] bool data type

[Shawn <tre...@gm...>]

This is the first time that I'm trying to use C's build in data type for 
true/false and I'm having some problems.

Basically, I'm trying to use bool to keep the program from displaying 
results if invalid data is entered.

  if (weight <= 0 || weight > 20000)
    cout<<"Please enter either a positive number or a weight of 20 
kilograms or less for your package.\t\t";

  if (distance < 10 || distance > 3000)
    cout<<"We don't ship to distances of less then 10 miles or more then 
3000 miles.\t\t";

If this is the case and they do enter invalid data, I want bool to stop 
the output of the program from printing on screen, I just want the 
program to tell the user that they need to enter the right information 
as prompted above. 
    
 cout<<"The total shipping charges for your package is 
$"<<setprecision(2)<<shippingCharges<<endl;

What's the best way to go about this?  I was thinking of declaring bool 
output = True in the beginning of the program and then right after those 
two input validation statements set output = false, but then what would 
I put just before the total shipping charges line so it wouldn't print?  
Also, I'm having problems setting output = false, it says false is 
undeclared.  I thought bool was a built in true/false data type?

thx