Thread: What did I do wrong? Need someone to review my code for an assignment

Write a C program that prompts for a variable number of integers, adds them up, averages them, and prints out the average.
The user will enter either an integer to be averaged or a sentinel of 999 indicating that no more numbers are to be entered. When the sentinel is entered, the program will exit the repetition loop. It will then compute and display the average of numbers entered.


I got a 85 but I feel I accomplished the task and should've been scored higher. The instructors feedback was Use int num and compare it with 999 to stop.
That way, two scanf() statements are not required.

insert

Code:

#include <stdio.h>


int main()
{
    
    float average, num,  total;
    int count, stop=0;


    count=0;
    total=0.0;


    
    while (stop != 999)


    {
        
        printf("\nenter a number ");
        scanf("%f", &num);
        count++;
        total += num;
        
        
        printf("the total is now %.f\n", total);
        printf("\nenter 999 to calculate the avg or 0 to continue ");
        
        scanf("%d", &stop);
        
        
        
    }
        
        
        average =total / count;
        printf("The average of all the numbers is: %.f", average);
            return 0;
        


}

Well, you did a good attempt, but you did not meet the requirements. You should check to see if num is 999 and if so, use the keyword break (I suggest) to break the loop (or check for it in the while condition) and then do the average and printing. You should not use the variable stop, nor using a second scanf.

This is what I could come up with. What do you guys think does it solve the question?

Code:

#include <stdio.h>


int main()
{
    
    float average,total, num;
    int count ;
    
    
    
    count=0;
    total=0;


    
    do


    {
        
        printf("\nenter a number ");
        scanf("%f", &num);
        if (num == 999)
        break;
        count++;
        total += num;


        
        
        
        printf("the total is now %.f\n", total);
        
        
        
        
        
        
    }
    while(1);
        
        
        
        average =total / count;
        printf("The average of all the numbers is: %.f", average);
            return 0;
        


}

Well, this seems ok, but the num!= 999 condition seems to be redundant. You could use

Code:

while(1)

or even better, stick to the while loop you had in your first attempt, and have as condition the sum != 999

Originally Posted by dmar0123

Yea I know its redundant didn't know what to place by while(). Where would I place the condition sum != 999 and do I declare sum=0; ?

It depends. For example, have you learnt how to define your own functions? One option is to move a certain part of the code for the loop into a function, then call the function to determine when to end the do while loop.

@ gura Yes I changed the while(num != 999); to while(1); But besides that

Actually defining my own functions is in the next chapter I tackle that assignment tonight. So haven't learned it yet.

Originally Posted by dmar0123

I changed the while(num != 999); to while(1);

Don't do that. Rather, change the entire do while loop into a while loop.

Originally Posted by dmar0123

Actually defining my own functions is in the next chapter

Okay, then don't worry about that for now.

Incidentally, you should remove all those extra blank lines and indent your code consistently, e.g.,

Code:

#include <stdio.h>


int main()
{
    float average, total, num;
    int count;

    count = 0;
    total = 0;

    while (1)
    {
        printf("\nenter a number ");
        scanf("%f", &num);
        if (num == 999)
            break;
        count++;
        total += num;

        printf("the total is now %.f\n", total);
    }

    average = total / count;
    printf("The average of all the numbers is: %.f\n", average);
    return 0;
}

Also, what happens if the user enters 999 as the very first input?

Also, what happens if the user enters 999 as the very first input?[/QUOTE]

It outputs a -1 because theres no integers fed into total variable. So if 999 is inputted in the very beginning it exits the loop but still tries to find the average. What is the real difference of a do while verses a while? My understanding of the concept is Do (the loop) until the while is proved false. The While loop will only run as long as it remains true.

Originally Posted by dmar0123

It outputs a -1 because theres no integers fed into total variable. So if 999 is inputted in the very beginning it exits the loop but still tries to find the average.

At that point, count is 0, so you have a division by 0 error. The -1 is just a symptom of that. You should check for this and handle the case accordingly.

Originally Posted by dmar0123

What is the real difference of a do while verses a while? My understanding of the concept is Do (the loop) until the while is proved false. The While loop will only run as long as it remains true.

The do while loop will run at least once. Running until it is "proved false" and running "as long as it remains true" are two different ways of saying the same thing, but notice that for the while loop, the test of the condition comes first, whereas for the do while loop it comes at the end of the iteration.