什麼是 struct,union,enumeration 的 tag ?
struct tag { member-list };
union tag { member-list };
enum tag { member-list };
union test1 { int a; };
test1 是 union tag.
struct tag { member-list };
union tag { member-list };
enum tag { member-list };
union test1 { int a; };
test1 是 union tag.