½5-3 :結構的功能要單一,是針對一種事務的抽象
說明:設計結構時應力爭使結構代表一種現實事務的抽象,而不是同時代表多種。結構中的各元素應代表同一事務的不同側面,而不應把描述沒有關系或關系很弱的不同事務的元素放到同一結構中。
示例:如下結構不太清晰、合理。
typedef struct STUDENT_STRU
{
unsigned char name[8]; /* student’s name */
unsigned char age; /* student’s age */
unsigned char sex; /* student’s sex, as follows */
/* 0 - FEMALE; 1 - MALE */
unsigned char
teacher_name[8]; /* the student teacher’s name */
unisgned char
teacher_sex; /* his teacher sex */
} STUDENT;
若改為如下,可能更合理些。
typedef struct TEACHER_STRU
{
unsigned char name[8]; /* teacher name */
unisgned char sex; /* teacher sex, as follows */
/* 0 - FEMALE; 1 - MALE */
} TEACHER;
typedef struct STUDENT_STRU
{
unsigned char name[8]; /* student’s name */
unsigned char age; /* student’s age */
unsigned char sex; /* student’s sex, as follows */
/* 0 - FEMALE; 1 - MALE */
unsigned int teacher_ind; /* his teacher index */
} STUDENT;
½5-4 :不要設計面面俱到、非常靈活的數據結構
說明:面面俱到、靈活的數據結構反而容易引起誤解和操作困難。
½5-5 :不同結構間的關系不要過于復雜
說明:若兩個結構間關系較復雜、密切,那么應合為一個結構。
示例:如下兩個結構的構造不合理。
typedef struct PERSON_ONE_STRU
{
unsigned char name[8];
unsigned char addr[40];
unsigned char sex;
unsigned char city[15];
} PERSON_ONE;
typedef struct PERSON_TWO_STRU
{
unsigned char name[8];
unsigned char age;
unsigned char tel;
} PERSON_TWO;
由于兩個結構都是描述同一事物的,那么不如合成一個結構。
typedef struct PERSON_STRU
{
unsigned char name[8];
unsigned char age;
unsigned char sex;
unsigned char addr[40];
unsigned char city[15];
unsigned char tel;
} PERSON;
½5-6 :結構中元素的個數應適中。若結構中元素個數過多可考慮依據某種原則把元素組成不同的子結構,以減少原結構中元素的個數
說明:增加結構的可理解性、可操作性和可維護性。
示例:假如認為如上的_PERSON結構元素過多,那么可如下對之劃分。
typedef struct PERSON_BASE_INFO_STRU
{
unsigned char name[8];
unsigned char age;
unsigned char sex;
} PERSON_BASE_INFO;
typedef struct PERSON_ADDRESS_STRU
{
unsigned char addr[40];
unsigned char city[15];
unsigned char tel;
} PERSON_ADDRESS;
typedef struct PERSON_STRU
{
PERSON_BASE_INFO person_base;
PERSON_ADDRESS person_addr;
} PERSON;
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