1. Structure and Union Types
程式設計
潘仁義
CCU COMM

2. Structure Type Definition
structured data objects, can be defined by users
#define STRSIZ 10 typedef struct { char name[STRSIZ]; double diameter; /* diameter in km */ int moons; /* number of moons */ double orbit_time, /* years to orbit sun once */ rotation_time; /* hours to rotate once */ } planet_t;
int main () { planet_t current_planet, blank_planet = {“”, 0,0,0,0}; int status = scan_planet(&current_planet); /* 等會看 */ current_planet = get_planet(); print_planet(current_planet); …

3. Assigning Values to Components of Variable current_planet

4. Function with a Structured Input Parameter

5. Function Comparing Two Structured Values for Equality

6. Function with a Structured Output Argument
也可寫成
& plnp->diameter,
&plnp->moons,
& plnp->orbit_time,
&plnp->rotation_time);

7. Data Areas of main and scan_planet during Execution of status = scan_planet (¤t_planet);

8. Function get_planet Returning a Structured Result Type

9. Data Type planet_t and Basic Operations
例如: 課本的 complex
Figure 11.10

10. Parallel Arrays and an Array of Structures
int id[50]; double gpa[50];
struct { int id; double gpa; } stulist[50];

11. Union types
Union
To deal with situations in which one needs a data object that can be interpreted in a variety of ways.
typedef union { int wears_wig; /*載假髮嗎?*/ char color[20]; } hair_t;
typedef struct { int bald; /*禿頭嗎?*/ hair_t h; } hair_info_t;

12. Function That Displays a Structure with a Union Type Component

13. Q & A
union 可以用 -> 嗎?
struct planet_t a, b; a = b; /* 可這麼寫嗎? */ if(a == b) {} /* 可這麼寫嗎? */
(*plnp).name *plnp.name plnp->name &plnp->name
小心：union 的內容該如何解釋?