Thread: Noob Help......Calculating volume and area of a sphere...

^^^
AHH! okay makes perfect sense, I corrected that and now the program compiles!!

im not getting the desired output though lol

if i enter a radius of 25, i should get a volume of 65449.847 and an area of 7853.982, instead i'm getting a volume of 9.425 and an area of 25.133 :S

is it because im not returning anything from the calc?

Code:

//INCLUDE SECTION
#include <stdio.h> //def's 4 printf, scanf, getchar, puts, gets, fflush
#include <conio.h> //def's for getch
#include <stdlib.h> //def's 4 system
#define PI 3.14159


//FUNCTION PROTOTYPES

void explanation(void);
void volume_calc(double *area, double *radius,double *volume);
void printresults(double area, double radius, double volume);

int main (void)
{
	double area, radius, volume;
	explanation();//FUNCTION CALL
	volume_calc(&area, &radius, &volume);//FUNCTION CALL
	printresults(area, radius, volume);

	printf("\n\t\t\tPRESS ANY KEY TO EXIT");
	_getch();
	return 0;
}

//FUNCTION DEFINITIONS
void explanation(void)
{
	system ("cls");
	puts ("This program will ask you to enter the RADIUS of a sphere...");
	puts ("and then calculate the volume and surface area...");

}
void volume_calc( double *area, double *radius, double *volume)
{
	//VARIABLE DECLARATIONS
	
	//GET USER INPUT
	printf ("\n\n\nPlease entert the radius of the sphere==> ");
	scanf ("%f", &*radius);
	

	//CALCULATIONS
	*volume=((4/3)*PI*(radius,3));
	*area=(4*PI*(radius,2));
	
	
	//OUTPUT
}	
void printresults(double area,double radius,double volume)

{
	printf("You entered a radius of %.3f...", radius);
	printf("\nthe volume of this sphere is ==> %.3f", volume);
	printf("\n\ntthe area of this sphere is ==> %.3f", area);
}

It's mainly because you have 4/3 when computing your volume. 4/3 is assumed by the compiler to be an integer division and the result is 1. What you probably want is a floating point result so just do 4.0/3.0 instead of 4/3.

^^^
yeah just noticed that, gave it a quick fix the numbers are a bit better, but still way off.....

for some reason the radius is coming up as -92556900000000000000.000 when i display it at the end....can't seem to figure this one out.. hmmmmm

Originally Posted by matt.s

^^^
yeah just noticed that, gave it a quick fix the numbers are a bit better, but still way off.....

for some reason the radius is coming up as -92556900000000000000.000 when i display it at the end....can't seem to figure this one out.. hmmmmm

What exactly is (radius,2) and (radius,3)?

(radius,2) = radius squared
(radius,3) = radius cubed

or at least it does according to my teacher, who could very well be wrong lol

ummm... NO!

Just use radius*radius for radius^2 and radius*radius*radius. it's not like you are raising to the 100th power.

If you wanted to do that you would write x = pow(radius,100); pow is a function defined in math.h

^^^^^
ahhh i see what your saying their, my teacher has clearly lost the plot i think lol :P

ahhhhhh its still giving me the wrong output! how can such a simple little program be so confusing!?! :S

Code:

//INCLUDE SECTION
#include <stdio.h> //def's 4 printf, scanf, getchar, puts, gets, fflush
#include <conio.h> //def's for getch
#include <stdlib.h> //def's 4 system
#define PI 3.14159


//FUNCTION PROTOTYPES

void explanation(void);
void volume_calc(double *area, double *radius,double *volume);
void printresults(double area, double radius, double volume);

int main (void)
{
	double area, radius, volume;
	explanation();//FUNCTION CALL
	volume_calc(&area, &radius, &volume);//FUNCTION CALL
	printresults(area, radius, volume);

	printf("\n\t\t\tPRESS ANY KEY TO EXIT");
	_getch();
	return 0;
}

//FUNCTION DEFINITIONS
void explanation(void)
{
	system ("cls");
	puts ("This program will ask you to enter the RADIUS of a sphere...");
	puts ("and then calculate the volume and surface area...");

}
void volume_calc( double *area, double *radius, double *volume)
{
	//VARIABLE DECLARATIONS
	
	//GET USER INPUT
	printf ("\n\n\nPlease entert the radius of the sphere==> ");
	scanf ("%f", &*radius);
	

	//CALCULATIONS
	*volume=((4.0/3.0)*PI*(*radius*(*radius)*(*radius)));
	*area=(4.0*PI*(*radius*(*radius)));
	
	
	
	//OUTPUT
}	
void printresults(double area,double radius,double volume)

{
	printf("You entered a radius of %9.3f...", radius);
	printf("\nthe volume of this sphere is ==> %.3f", volume);
	printf("\n\ntthe area of this sphere is ==> %.3f", area);
}

What's the input and output now?

Input: 25

Output:
You entered a radius of -925596047186160310000000000000000000000000.000...
The Volume of the sphere is: -33164118186955090000000000000000000000000000.000.. ...
The Area of the sphere is: 10765953004987781000000000000000000000000000.000.. ..

Try printing %lf

^^
same output

kinda whack no? :S

scanf ("%lf", radius); <--- correct

You undo and do an indirect, which means you put neither. Also the %lf again for double.

Ohhhh i was doing the %lf in the wrong place! and your right, its working perfect now! Thank you so much, greatly appreciated!!!!

Nice catch! I didn't see that coming.