Thread: New to this type of Programming, please help?

I just started a new programming class last week, using the free Microsoft Visual C++. This is all new to me, so I apologize in advance if this seems like a very minor problem. Anywho, the program we're required to do this week is one where the user can enter in a radius, and the program will compute the surface area and volume of a sphere. I'm required to use doubles though, instead of floats, and our teacher said to use the #define function to define pi.

This is what I've come up with so far, and it doesn't seem to be working. I've been tweaking things here and there, but it doesn't seem to work. Can anybody point out where I've gone wrong? Thank you!

Code:

#include <stdio.h>
 
int main () {
       double r;
       double surface_area_sphere, volume_sphere;
 
#define pi 3.141593;
       printf("Enter radius of sphere (cm): ");
       scanf("%lf",&r);
      
       printf("Radius: %lf\n",&r);
 
       surface_area_sphere = 4.0*pi*r*r;
       printf("Surface Area: %lf\n", surface_area_sphere);
 
       volume_sphere = (4.0/3)*pi*r*r*r;
       printf("Volume: %lf\n", volume_sphere);
 
       return 0;
}

This is the error it gives me:

Code:

1>------ Build started: Project: Program 2, Configuration: Debug Win32 ------

1>  prog2_io.c

1>prog2_io.c(9): warning C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.

1>stdio.h(304) : see declaration of 'scanf'

1>prog2_io.c(13): error C2100: illegal indirection

1>prog2_io.c(13): warning C4552: '*' : operator has no effect; expected operator with side-effect

1>prog2_io.c(16): error C2100: illegal indirection

1>prog2_io.c(16): warning C4552: '*' : operator has no effect; expected operator with side-effect

========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Also, after the program runs, the first printf line will pop up prompting the user to enter a radius, and then when you click enter it spits out a Volume, but I don't think it's computing correctly. For example, if you enter in a radius of 1, it'll give you a volume of 3.141593.

I am surprised this compiled.

Code:

#define pi 3.141593;

You need to remove the ; at the end.

My results:

Code:

Radius: 1.000000
Surface Area: 12.566372
Volume: 4.188791

Thanks so much! It's working fine now.