C Programming - Average

Question

Okay I'm entirely stuck here and I do apologise if this inconviences you guys in any way but I need your help.

I'm currently learning C by myself and slowly getting there, started yesterday. So I thought I would give myself a task on having the user input 3 numbers and the program would have to find the average number between those three.

Here is my code:

#include <stdio.h>

int main() {

    int firstnum, secnum, thirnum, finalnum;

    printf("Enter the first number \n");
    scanf("%f",&firstnum);

    printf("Enter the second number \n");
    scanf("%s",&secnum);

    printf("Enter the third number \n");
    scanf("%t",&thirnum);

    finalnum = (firstnum +secnum+thirnum)/3;
    printf("The average value is: " finalnum);

return finalnum;

}

`"%d"` is the appropriate format specifier to `scanf` or `printf` an `int`. — Klas Lindbäck, Dec 15 '15 at 12:58
Use `printf("The average value is: %d", finalnum);`, but beware that you're performing integer division (http://mathworld.wolfram.com/IntegerDivision.html). Consider floats. — harre, Dec 15 '15 at 12:59
Stack Overflow is not an interactive tutorial nor a substitute for C programming books/studies. You'll have to study the basics mentioned in chapter 1 of your book. Also, when asking a question on SO, clearly state what problems you're having, not just dump some code and say "it's not working". In this case you get compiler errors, so you should have posted them with the question. — Lundin, Dec 15 '15 at 14:30

harre · Accepted Answer · 2015-12-15T13:14:21.600

Reading integers or floats: Correct format specifier

For integers you'll need %dand for doubles %lf. Read more about those elsewhere.

E.g.

scanf("%d",&firstnum);

Printing integers or floats

E.g.

printf("The average value is: %d", finalnum);

Avoid integer division: casting or all floats

See http://mathworld.wolfram.com/IntegerDivision.html

E.g.

double finalnum = (firstnum +secnum+thirnum)/3.0;

Or use floats for all types.

double firstnum, secnum, thirnum, finalnum;

Return 0 for success in main

return 0;

score 0 · Answer 2 · edited May 23 '17 at 11:53

0

I found the fix linking with the comments made by harre and Klas Lindbäck. Thank you both.

I changed my format specifiers to %d as suggested. I then changed my printf line a little bit more.

I then tried to make a float with my int > finalnum but it didn't work. All this did was continously return the average as '0' so I placed finalnum back as an int. This is how the code looks now:

#include <stdio.h>

int main() {

    int firstnum, secnum, thirnum;
    int finalnum;

    printf("Enter the first number \n");
    scanf("%d",&firstnum);

    printf("Enter the second number \n");
    scanf("%d",&secnum);

    printf("Enter the third number \n");
    scanf("%d",&thirnum);

    finalnum = (firstnum + secnum + thirnum)/3;
    printf("The average value is: %d", finalnum);

return finalnum;

}

Thank you all :)

edited May 23 '17 at 11:53

Community

1
1

answered Dec 15 '15 at 13:10

Jordan Savell

27
6

This still isn't what you want. You're still doing integer division here. To do what you want, try the following: 1) Replace all `int` with `float`. 2) Replace all `%d` with `%f`. 3) Replace `3` with `3.0` (though this part isn't strictly necessary but technically correct). The code will then behave as you expect. – Samidamaru Dec 15 '15 at 14:32
Yeah float now works for some reason. Lesson learnt - use float when not doing integer division. Thank you – Jordan Savell Dec 20 '15 at 16:16

score 0 · Answer 3 · answered Dec 15 '15 at 13:15

0

Use float instead of int to get decimal precision otherwise the finalnum would get rounded off

use this for printing float printf("The average value is: %f",finalnum);

for more on printf you can refer this link http://www.tutorialspoint.com/c_standard_library/c_function_printf.htm

answered Dec 15 '15 at 13:15

Rishi Deorukhkar

179
4
15

This is not a round off issue but a result of integer division. – harre Dec 15 '15 at 13:31

C Programming - Average

3 Answers3