Stdlib h C Tutorial

Item Value
Header filestdlib.h
Declarationvoid exit(int exit_code);
Functioncauses immediate, normal termination of a program.
Termination functions registered by atexit() are called, and any open files are flushed and closed.
The value of exit_code is passed to the calling process.
If the value of exit_code is zero, or EXIT_SUCCESS, normal program termination is assumed.
A nonzero value, or EXIT_FAILURE, is used to indicate an implementation-defined error.

#include 
  #include 
  int main(void)
  {
    char choice;
    do {
      printf("Enter names (E)\n");
      printf("Delete name (D)\n");
      printf("Print (P)\n");
      printf("Quit (Q)\n");
      choice = getchar();
    } while(!strchr("EDPQ", toupper(choice)));
    if(choice=='Q') exit(0);
    return choice;
  }