Calculate the area and volume of a sphere in C

Question

The task was to find the Area and Volume of a sphere using functions and an additional task was provided to give a function to find the powers of the radius separately (using another function) and then call it in the functions of area and volume. I can't figure out the way to call the radius function for different powers. The formula for Surface area is 4*PI*r(power 2) The formula for the Volume is 4/3 *(PI)*r(power 3)

#include <stdio.h>
#include <math.h>
#include <conio.h>
#define PI 3.142

float surface(int x);
float volume(int y);
int radius();
int main()
{
    int r;
    float a, b;
    clrscr();
    printf("Enter the radius :");
    scanf("%d", &r);
    a=surface(r);
    b=volume(r);
    printf("Surface Area =%f", a);
    printf("\n");
    printf("Volume =%f", b);
    getch();
    return 0;
 }
int radius(int z)
{
    int f;
    f=z*z;
    return (f);
}
float surface(int x)
{
    float s;
    s = 4*PI*radius(x);
    return (s);
}
float volume(int y)
{
    float v;
    v = (4*PI*radius(y)/3);
    return (v);
}

I was also instructed to "Refrain from using Arrays or others methods of solving this question."

I cant figure out the way to call the radius function for different powers. An explanation or the correct way to solve this would be helpful!

It's not really clear what the problem is here. Can you provide some examples of how the code isn't working as you would expect. — Sean, Feb 20 '17 at 15:02
Your `radius` function should be called `square` (or `pow2`); you should invent another function called `cube` (or `pow3`). They should both take a single parameter, probably named `n`. The parameters to `surface` and `volume` should simply be called `r` (for "radius"). — Roger Lipscombe, Feb 20 '17 at 15:02
Not an apparent issue , it just gives a value tha'ts not correct. So technically its wrong.@Sean — Syed Hasan, Feb 20 '17 at 15:04
Yes that's what I am seeking @HighPerformanceMark. How do I get the function to figure out the power I seek because all I provide the function is the radius. — Syed Hasan, Feb 20 '17 at 15:06
Sean meant to tell us the result for some example input, so for `5` input the expected area would be `25PI` and volume `500PI/3` but actual result was ... — niceman, Feb 20 '17 at 15:06
Are you allowed to use build-ins? You could simply use `pow(radius,exponent)` [Look here](https://www.tutorialspoint.com/c_standard_library/c_function_pow.htm) — izlin, Feb 20 '17 at 15:08
No, need to call a different function for the powers of the 'radius'. — Syed Hasan, Feb 20 '17 at 15:11
@izlin: `pow` is not a built-in function. C does not have built-in functions. — too honest for this site, Feb 20 '17 at 15:23
Possible duplicate of [The most efficient way to implement an integer based power function pow(int, int)](http://stackoverflow.com/questions/101439/the-most-efficient-way-to-implement-an-integer-based-power-function-powint-int) — James Snook, Feb 20 '17 at 15:26
@izlin, `pow(3)` is not a good example of good coding style. It's implementation uses `log(3)` and `exp(3)` to compute the power and only squares and cubes are involved in the problem (which are better specified as `x*x` and `x*x*x`, not involving logarithm calculations, which involve series approximations) If the second parameter of `pow(3)`, some optimization is achieved not using it (of course, this optimization can be done inside the function, but even so, a cube involves only two multiplications, no tests, no calling overhead) — Luis Colorado, Feb 21 '17 at 08:05

Klas Lindbäck · Accepted Answer · 2017-02-20T15:28:42.977

3

radius is not really the best name for a function thet computes the square or power of 3. I would call the function power instead. And to make it do different powers you need the exponent as a parameter. You can then use a loop to calculate the power.

/* Calculate the power for exponents >= 0 */
int power(int radius, int exponent) {
    int i;
    int result = 1;

    for (i = 0; i < exponent; i++) {
        result = result * radius;
    }
    return result;
}

You use it like this:

int radius;
// After assigning a value to radius you can call power() like this:
int square = power(radius, 2);
int cube = power(radius, 3);

edited Feb 20 '17 at 15:28

answered Feb 20 '17 at 15:09

Klas Lindbäck

33,105
5
57
82

Thank you @KlasLindbäck. Can I call in multiple parameters like this in a function? – Syed Hasan Feb 20 '17 at 15:21
1

@SyedHasan Yes. You can add as many parameters as you need when you create your function, You need to match all parameters when you call the function. (For intermediate/advanced users there is something called variadic arguments, which is used for functions that take a variable number of arguments. See https://en.wikipedia.org/wiki/Variadic_function) – Klas Lindbäck Feb 20 '17 at 15:33
Thank you very much, solved my issue with another program! – Syed Hasan Feb 20 '17 at 15:41
@KlasLindbäck, have you ever heard about the quick power algorithm, applicable when the exponent is an integer? – Luis Colorado Feb 21 '17 at 08:08
@LuisColorado I have, and I am familiar with it. In this case I chose to tailor the complexity of the answer to the level of the OP (and to the current problem. The quick power algorithm isn't quicker for exponents as small as 2 or 3). – Klas Lindbäck Feb 21 '17 at 08:42
@KlasLindbäck, ok, you're right of course!!! :) – Luis Colorado Feb 22 '17 at 12:27
@niceman, no... as i goes from 0, the times it passes through the loop is exactly `exponent` times. – Luis Colorado Feb 22 '17 at 12:34
@KlasLindbäck, I don't understand why you claim about not calling `radius` the function, and then you call `radius` the formal parameter, that should be called `base`. Shouldn't it? – Luis Colorado Feb 22 '17 at 12:36

score -2 · Answer 2 · answered Feb 20 '17 at 15:03

-2

int cube(int z){
    return z * z * z;
}

or

#include<math.h> // at the top
... 
int power(int base, int exponent){
    return pow(base,exponent);
}

answered Feb 20 '17 at 15:03

user3853544

581
3
9

this doesn't answer the question fully – niceman Feb 20 '17 at 15:04
@user3853544, Why not define a second function `power_bis` that calls `power` to finally call `pow`? or `power_tris` that calls `power_bis`, that calls `power` to finally call `pow` ??? – Luis Colorado Feb 22 '17 at 12:38
@Luis ColoradoThe way OP worded the question it sounded as if he was suposed to create his own function. Otherwise just call pow( ... ) on its own. – user3853544 Feb 22 '17 at 13:31

Calculate the area and volume of a sphere in C

2 Answers2