C语言库atexit()函数

#include <stdio.h>
#include <stdlib.h>

void functionA () {
   printf(This is functionA\n);
}

int main () {

   /* register the termination function */
   atexit(functionA );

   printf(Starting  main program...\n);
   printf(Exiting main program...\n);

   return(0);
}