C 언어 제한 사항

/* documentation section */
preprocessor directives
global declaration
main ( ){
   local declaration
   executable statements
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return type function name (argument list){
   local declaration
   executable statements
}

/* Author : Tutorialspoint
Aim : Program for finding circumference of circle*/
#include<stdio.h>
#include<conio.h>
#define PI 3.1415
main ( ){
   float c, r;
   clrscr ( );
   printf ("enter radius of circle");
   scanf ("%f", &r);
   c = 2 * PI * r;
   printf ("Circumference = %f", c);
   getch ( );
}

Enter radius of circle r=4
Circumference of circle c=25.132000