float circleArea(float theRadius); 
float pictureSurfaceArea(float pictureWidth, float pictureHeight);
int main(int argc, const char * argv[]) // the argument inside main() is to do with memory allocation
{
	NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; //memory allocation
 
    float circleRadius, circleSurfaceArea, pictureWidth, pictureHeight, pictureArea;
 
 
	pictureWidth = 8.0;
    pictureHeight = 4.0;
    circleRadius = 5.0;
    pictureArea = pictureSurfaceArea(pictureWidth, pictureHeight);
    circleSurfaceArea = circleArea(circleRadius);
 
 
	NSLog(@" The area of the circle is %.2fcm.", circleSurfaceArea);
	NSLog(@" However the area of my picture is %.0fcm.", pictureArea);
 
 
	[pool drain]; //memory clean up
 
    return 0;
}
 
//circle area algorithm
float circleArea(float theRadius)
{
    float theArea;
    theArea = 3.1416 * theRadius * theRadius;
    return theArea;
}
// picture area algorithm
float pictureSurfaceArea(float pictureWidth, float pictureHeight)
{
	float pictureSpace;
	pictureSpace = pictureWidth * pictureHeight;
	return pictureSpace;
}