Problem with area of circle program

Hi

The program itself is running fine at first, but for some reason when I enter the radius for multiplication, I keep getting the Area result as 0.
Any help would be much appreciated! ;) :)

Code:

---

#include <stdio.h>
#include <conio.h>

#define PI 3.141569


float process(float radius);

int main()
{
float area, radius;
int count;

printf("To STOP, enter 0 for the radius\n"); printf("Radius = ? ");
scanf("%f", &radius);

for (count = 1; radius !=0; ++count) {

if (radius < 0)
area = 0;
else
area = process(radius);

printf("Area = %f\n", area);

printf("\nRadius = ? ");
scanf("%f", &radius);
}
}

float process(float radius)
{
float a;
a = PI * r * r;
getch();
return 0;
}



---

Code:

---

float process(float radius)
{
float a;
a = PI * r * r;
getch();
return 0;
}

---

My friend the errors are in the function process... you've passed by copy the fload radius but in the function you use a variable r that isn't declared (first error) so you have to replace the R with the RADIUS passed in the function :-) and the second error is that into the function you've returned 0, logically anything that u have typed in the main would be 0!!! you have to return the variable 'a' and you have to calculate as 'a = PI * radius * radius; like following:

Code:

---

float process(float radius){
float a;
a = PI * radius * radius;
return a;
}

---

so also the getch is unuseful... and also the library conio.h is unuseful for this type of program :)

Edited the code as suggested and I've got the following errors. :( Any suggestions?
error LNK2005: _main already defined in n.obj

error LNK2005: "float __cdecl process(float)" (?process@@YAMM@Z) already defined in n.obj
fatal error LNK1169: one or more multiply defined symbols found

Your linker is telling you that it already has a definition for a function called 'process' that returns a float and operates on a float. Meaning the file n.obj has a function defined:

Code:

---

float process(float somevar)
{
...
}

---

And you are including that object file in your compilation of THIS code.