/*
* GENESIS Copyright (c) 1986, 1990 by John J. Grefenstette
* This program may be freely copied for educational
* and research purposes. All other rights reserved.
*
* file: extern
# include
void main()
{
/* 说明本文件将要使用其它文件中的函数 */
extern int multiply();
extern int sum();
int a, b;
int result;
printf("Please input a and b: ");
scanf("%d, %d", &a, &
