typedef

http://www.cnblogs.com/JCSU/articles/1299051.html

typedef enum

意義：用typedef關鍵字將枚舉類型定義成別名，並利用該別名進行變量聲明：

typedef enum workday
{
    saturday,
    sunday = 0,
    monday,
    tuesday,
    wednesday,
    thursday,
    friday
} workday; //此處的workday爲枚舉型enum workday的別名

workday today, tomorrow; //變量today和tomorrow的類型爲枚舉型workday，也即enum workday

enum workday中的workday可以省略：

typedef enum
{
    saturday,
    sunday = 0,
    monday,
    tuesday,
    wednesday,
    thursday,
    friday
} workday; //此處的workday爲枚舉型enum workday的別名

workday today, tomorrow; //變量today和tomorrow的類型爲枚舉型workday，也即enum workday

也可以用這種方式：

typedef enum workday
{
    saturday,
    sunday = 0,
    monday,
    tuesday,
    wednesday,
    thursday,
    friday
};

workday today, tomorrow; //變量today和tomorrow的類型爲枚舉型workday，也即enum workday

typedef struct

http://www.cnblogs.com/qyaizs/articles/2039101.html