C语言宏#define中#，##，#@和\的用法: https://blog.csdn.net/yishizuofei/article/details/81022590

define还有自动拼接字符串的功能, 如:

#define str "a" "b"  // 相当于str是"ab"
#define x "+"
#define str2 "a" x "b" //相当于str2是"a+b"
void main(){
  printf(str);
  printf(str2);
}
//将打印出 aba+b