2.4 Exemple de programme C

 
#include <stdio.h>
#define  PI 3.14159
/*  calcul de la surface d'un cercle */
main()
{
  float rayon, surface;
  float calcul(float rayon); 
  printf("Rayon = ? ");
  scanf("%f", &rayon);
  surface = calcul(rayon);
  printf("Surface = %f\n", surface);
}
/* definition de fonction */
float calcul(float r)
{
/* definition de la variable locale */
  float a; 
  a = PI * r * r;
  return(a);
}