Thread: Help With Calculation

This is written in C. The program works, but the calculation is wrong, can someone tell me what I am doing wrong?

Thank You

Code:

#include "stdafx.h"
#include <math.h>

#using <mscorlib.dll>

using namespace System;

// Function prorotypes

 void sphere_volume (double);

// PI is a constant

const double PI=3.14159;


int _tmain()


{
	// Integer local to Main to store initial radius value
double r;

	printf("Please Enter A Positive Radius Value\n");
	scanf("%lf", &r);

// If Else Function To Make Sure The User Types A Positive and Not A Negative Integer.

	if (r >= 0)
		sphere_volume (r);

	else
		printf("You Must Enter A Positive Integer!!!! Not A Negative Integer!!!\n");

	return 0;

}

// This Is The Fnction That Does The Calculations For The Volume.

void sphere_volume (double radius)

{
	double  radius_cubed;

	double exponent=3;

	double volume;

	printf("This Is The Test To See If R Was Passed To The Function: %lf\n", radius);

	radius_cubed=pow(radius, exponent);

	volume=(4/3)*PI*radius_cubed;

	printf("The Volume Of The Sphere is %lf\n", volume);
}