结构体的一些形式理解

//1、 struct book {int a;int b;char c;};//结构声明 struct book library;//结构变量定义 //上述等价于 struct book {int a;int b;char c;} library; //2、 struct {int a;int b;char c;} library;//不带标记 //3、 typedef struct complex {float real;float imag;} COMPLEX;//可以用COMPLEX来替代 struct complex typedef struct {float real;float imag;} COMPLEX;//省去了结构标志complex，此时COMPLEX代替 struct {float real;float imag;} /*实际定义结构体时，可以这样写： struct complex library； complex library; COMPLEX library; */