C语言变量声明

#include <stdio.h>

// Variable declaration:
extern int a b;
extern int c;
extern float f;

int main () {

   /* variable deFinition: */
   int a b;
   int c;
   float f;

   /* actual initialization */
   a = 10;
   b = 20;

   c = a + b;
   printf("value of c : %d \n" c);

   f = 70.0/3.0;
   printf("value of f : %f \n" f);

   return 0;
}