warning: incompatible implicit declaration of built-in function

http://341719xubin.blog.163.com/blog/static/132920793200911415911325/

頭檔案包含缺少，

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>