頭文件包含缺少，
main.c:10: warning: incompatible implicit declaration of built-in function 'memset'加入#include<string.h>
main.c:13: warning: incompatible implicit declaration of built-in function 'printf'加入#include<stdio.h>
main.c:14: warning: incompatible implicit declaration of built-in function 'exit' 加入#include<stdlib.h>
