C/stdlib.h/atexit

atexit: causes the function pointed to by func to be called upon normal program termination

<source lang="cpp">

//Declaration: int atexit(void (*func)(void)); //Return: returns zero if the function is successfully registered as a termination function and nonzero otherwise.

 #include <stdlib.h>
 #include <stdio.h>
 void done(void);
 int main(void)
 {
   if(atexit(done)){
         printf("Error in atexit().");
   }
   return 0;
 }
 void done(void)
 {
   printf("Hello There");
 }
        

/* Hello There*/

      </source>