Programming Forums > Application Development > C++

darkone916 · Jan 11th, 2006, 1:14 PM

I borrowed a C++ book and i went to the beginning to revise Control Structures...

This is a code using loops.

#include <iostream>
#include <cstdlib>
using namespace std;

int main()
{
    int i=0;
    int num;
    int total=0;
    double average;
    
    while (num != -1)
    {
        cout << "Enter the number -1 to break" << endl;
        cin >> num;
        total = total+num;
        i++;
    }
    
    if (total = 0)
    exit(1);
    
    else
    {
        average = total / i;
        cout << average << endl;
    }
    cin.ignore();
    cin.get();
    return 0;
}

This programme is supposed to take numbers until (num==-1), after that, it will add up all the numbers and find the average.
But the problem is that the average is always nought...

.

Anyway, i spent a long time looking for the problem, yet i'm sure its just a silly thing i missed. Thank you.

Polyphemus_ · Jan 11th, 2006, 1:26 PM

(Toggle Plain Text)

    if (total = 0)
    exit(1);

You set total to 0 there, so your answer will always be 0. Use this code instead:

(Toggle Plain Text)

if (total == 0)
 return 1;

Secondly, you should cast i and total to doubles before dividing:

(Toggle Plain Text)

average = (double) total / (double) i;

And thirdly, your code adds -1, your loop should terminate before adding it:

(Toggle Plain Text)

while (1)
    {
        cout << "Enter the number -1 to break" << endl;
        cin >> num;
        if(num == -1)
               break;

        total = total + num;
        i++;
    }

I think that will do it.

Kaja Fumei · Jan 11th, 2006, 1:28 PM

EDIT: I made the same three fixes as Polyphemus_, but he beat me to it.

darkone916 · Jan 11th, 2006, 1:33 PM

Thanks!

That worked indeed!

Anyway, in the "Secondly" part, that is called typecasting right?
Is it the same as :

(Toggle Plain Text)

static_cast <double>(total)

Thanks again!

Polyphemus_ · Jan 11th, 2006, 2:05 PM

Quote:

Originally Posted by Kaja Fumei

EDIT: I made the same three fixes as Polyphemus_, but he beat me to it.

Lol, only two minutes diffence...

Anytime, darkone.. and yeah, I believe that's the same as static_cast. Using just (double) will safe typing, though

.

Klarre · Jan 11th, 2006, 2:08 PM

Quote:

Originally Posted by darkone916

Thanks!

That worked indeed!

Anyway, in the "Secondly" part, that is called typecasting right?
Is it the same as :

(Toggle Plain Text)

static_cast <double>(total)

Thanks again!

(Toggle Plain Text)

static_cast<double>(x); // The C++ way
(double)x; // C cast

C++ also have more casts than C, that only got one. These are

(Toggle Plain Text)

const_cast
reinterpret_cast
dynamic_cast

Cache · Jan 11th, 2006, 2:09 PM

Perhaps it would also be a good idea to initialize 'num' with a value other than -1 before the while loop?

darkone916 · Jan 11th, 2006, 2:11 PM

Thanks Poly, Klarre and Kaja, thanks, i really need to improve! :o

Jan 11th, 2006, 1:14 PM	#1
darkone916 Hobbyist Programmer Join Date: Jul 2005 Location: Oman Posts: 125 Rep Power: 4	average = 0 I borrowed a C++ book and i went to the beginning to revise Control Structures... This is a code using loops. (Toggle Plain Text) #include <iostream> #include <cstdlib> using namespace std; int main() { int i=0; int num; int total=0; double average; while (num != -1) { cout << "Enter the number -1 to break" << endl; cin >> num; total = total+num; i++; } if (total = 0) exit(1); else { average = total / i; cout << average << endl; } cin.ignore(); cin.get(); return 0; } #include <iostream> #include <cstdlib> using namespace std; int main() { int i=0; int num; int total=0; double average; while (num != -1) { cout << "Enter the number -1 to break" << endl; cin >> num; total = total+num; i++; } if (total = 0) exit(1); else { average = total / i; cout << average << endl; } cin.ignore(); cin.get(); return 0; } This programme is supposed to take numbers until (num==-1), after that, it will add up all the numbers and find the average. But the problem is that the average is always nought... . Anyway, i spent a long time looking for the problem, yet i'm sure its just a silly thing i missed. Thank you. __________________ From the bottom of the stone steps... ...i'm calling still.

Jan 11th, 2006, 1:26 PM	#2
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	(Toggle Plain Text) if (total = 0) exit(1); if (total = 0) exit(1); You set total to 0 there, so your answer will always be 0. Use this code instead: (Toggle Plain Text) if (total == 0) return 1; if (total == 0) return 1; Secondly, you should cast i and total to doubles before dividing: (Toggle Plain Text) average = (double) total / (double) i; average = (double) total / (double) i; And thirdly, your code adds -1, your loop should terminate before adding it: (Toggle Plain Text) while (1) { cout << "Enter the number -1 to break" << endl; cin >> num; if(num == -1) break; total = total + num; i++; } while (1) { cout << "Enter the number -1 to break" << endl; cin >> num; if(num == -1) break; total = total + num; i++; } I think that will do it.

Jan 11th, 2006, 1:33 PM	#4
darkone916 Hobbyist Programmer Join Date: Jul 2005 Location: Oman Posts: 125 Rep Power: 4	Thanks! That worked indeed! Anyway, in the "Secondly" part, that is called typecasting right? Is it the same as : (Toggle Plain Text) static_cast <double>(total) static_cast <double>(total) Thanks again! __________________ From the bottom of the stone steps... ...i'm calling still.

Jan 11th, 2006, 2:11 PM	#8
darkone916 Hobbyist Programmer Join Date: Jul 2005 Location: Oman Posts: 125 Rep Power: 4	Thanks Poly, Klarre and Kaja, thanks, i really need to improve! :o __________________ From the bottom of the stone steps... ...i'm calling still.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Jan 11th, 2006, 1:28 PM	#3
Kaja Fumei Hobbyist Programmer Join Date: Oct 2005 Posts: 134 Rep Power: 4	EDIT: I made the same three fixes as Polyphemus_, but he beat me to it.

Jan 11th, 2006, 2:09 PM	#7
Cache Hobbyist Join Date: Sep 2005 Posts: 266 Rep Power: 4	Perhaps it would also be a good idea to initialize 'num' with a value other than -1 before the while loop?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Programming Forums > Application Development > C++

average = 0