Thread: Super Beginner Question

I am just working on my very first C program ever for a programming class. The assignment is very simple. Enter a program that takes the radius of a sphere and finds the surface area and volume of it. My program compiles, but when it runs it doesn't run properly and I was wondering if someone could look over it and help me figure out whats wrong with it.

Heres the code:

Code:

/* Sphere.c */
#include<stdio.h>
#include<stdlib.h>
int main(void){
   double r, v, s;
   const double pi = 3.141592654;

   printf("Enter the radius of the sphere: ");
   r = scanf(" %lf ", &r);
   v = 4.0/3.0*pi*r*r*r;
   s = 4*pi*r*r;
   printf("The volume is %lf and the surface area is %lf.", v, s);

   return 0;
}

Stop assigning scanf's return value to r. You pass the objects that you want *scanf functions to assign as pointers, and if it works, the function takes care of the assignment for you. All the *scanf functions return the number of objects assigned, which means that you are overwriting the user's input at every run.

Might as well read this.

It is good that you are paying attention to scanf's return value, however. It's the only way to discern if the function worked correctly.

Ok I fixed it, but now when I run it i get this error:
Segmentation Fault

heres the new code.

Code:

/* Sphere.c */
#include<stdio.h>
#include<stdlib.h>
int main(void){
   double r, v, s;
   const double pi = 3.141592654;

   printf("Enter the radius of the sphere: ");
   r = scanf(" %lf" );
   v = 4.0/3.0*pi*r*r*r;
   s = 4*pi*r*r;
   printf("The volume is %lf and the surface area is %lf.", v, s);

   return 0;
}

Don't miss the point now.

Code:

/* Sphere.c */
#include<stdio.h>

int main(void){
   double r, v, s;
   const double pi = 3.141592654;
   int check = 0;
   
   printf("Enter the radius of the sphere: ");
   check = scanf("%lf", &r ); 
   /* Store whatever the user typed at the address of r. */ 
   if( check == 1 ) {
     /* Recall that scanf returns the number of objects assigned, 
        like the rest of the *scanf family. */
     v = 4.0/3.0*pi*r*r*r;
     s = 4*pi*r*r;
     printf("The volume is %lf and the surface area is %lf.", v, s);
   }
   
   return 0;
}

Originally Posted by dwks

[edit]
But it is bad that scanf()'s return value is being assigned to a double, the same variable that the OP wanted to store scanf()'s value into. [/edit]

That's what I said. People have really struggled to pay attention to what I write lately. I appologize for this. There must be something wrong with the way that I write.