在 C 中的 scanf 中使用定义（类型说明符）[重复]

Question

所以我原来的代码是：

scanf("%20s %20s", Player1.name, Player2.name);

如果我想让我的代码更灵活，我可以这样做，或者有类似的方法：

.#define MAX_NAME_IN 20
...
scanf("%MAX_NAME_INs %MAX_NAME_INs", Player1.name, Player2.name);
...

Answer 1

#define MAX_NAME_IN 20
#define S_(x) #x
#define S(x) S_(x)
...
scanf("%" S(MAX_NAME_IN) "s %" S(MAX_NAME_IN) "s", Player1.name, Player2.name);

---

用这样的预处理器替换

S(MAX_NAME_IN) => S_(20) => "20"

scanf("%" S(MAX_NAME_IN) "s %" S(MAX_NAME_IN) "s", Player1.name, Player2.name);
↓
scanf("%" "20" "s %" "20" "s", Player1.name, Player2.name);

并且"%" "20" "s %" "20" "s" 被编译器解释为"%20s %20s"。