C言語構造体と共同体

1.構造体

 1 #include 
 2 
 3 //     File
 4 struct File {
 5     char *name;
 6     int size;
 7 };
 8 
 9 //     People  typedef   
10 struct _People {
11     char *name;
12     int age;
13 };
14 
15 typedef struct _People People;
16 
17 //     Person  typedef        
18 typedef struct _P {
19     char *name;
20     int age;
21 } P;
22 
23 int main() {
24 
25     //   File
26     struct File file;
27     file.name = "Clion";
28     file.size = 100;
29 
30     printf("File name is %s,File size is %d.
", file.name, file.size);
31 
32 //---------------------------------------------------------------------
33     People people = {"Susan", 20};
34 
35     printf("Name is %s,Age is %d.
", people.name, people.age);
36 
37 //---------------------------------------------------------------------
38     P p = {"Alex", 22};
39     printf("Name is %s,Age is %d.
", p.name, p.age);
40 
41 
42     return 0;
43 }

 
2.構造体ポインタ

 1 #include 
 2 #include 
 3 
 4 typedef struct _Student {
 5     const char *name;
 6     int age;
 7 } Student;
 8 
 9 void func() {
10     Student *s4 = malloc(sizeof(Student));
11     s4->name = "Lucy";
12     s4->age = 18;
13     Student *s5 = s4;
14     s4->age = 20;
15     printf("(%s,   %d),(%s,   %d)
", s4->name, s4->age, s5->name, s5->age);
16 }
17 
18 Student *createStudent(char *name, int age) {
19     Student *s = malloc(sizeof(Student));
20     s->name = name;
21     s->age = age;
22     return s;
23 }
24 
25 void deleteStudent(Student *p) {
26     free(p);
27 }
28 
29 int main() {
30 
31     Student s1 = {"Jim", 16};
32     Student s2 = s1;
33     printf("(s1.name = %s,s1.age = %d),(s2.name = %s,s2.age = %d)
", s1.name, s1.age, s2.name, s2.age);
34     s2.age = 20;
35     printf("(s1.name = %s,s1.age = %d),(s2.name = %s,s2.age = %d)
", s1.name, s1.age, s2.name, s2.age);
36 
37     printf("
");
38     //     
39     Student *s3 = &s1;
40     s1.age = 30;
41     printf("(s1.name = %s,s1.age = %d),(s3.name = %s,s3.age = %d)
", s1.name, s1.age, s3->name, s3->age);
42 
43 //-----------------------------------------------------------------------------------------------------
44     printf("
");
45     func();
46 
47 //-----------------------------------------------------------------------------------------------------
48     printf("
");
49     Student *s = createStudent("Daisy", 22);
50     printf("%s,   %d
", s->name, s->age);
51     deleteStudent(s);
52 
53 
54     return 0;
55 }

 
 
3.共同体

 1 #include 
 2 #include 
 3 
 4 //     
 5 typedef union _BaseData {
 6     char ch;
 7     uint8_t ch_num;
 8     uint32_t num;//         sizeof(BaseData)   4  -->                
 9 } BaseData;
10 
11 //     
12 typedef struct _Data {  //    
13     uint8_t a;  //1  Data  1
14     uint8_t b;  //1  Data     2
15     uint32_t c; //4  Data     8
16     uint8_t d;  //1   Data     12
17 }__attribute__((__packed__)) Data;  //__attribute__((__packed__))     
18 
19 //                   
20 typedef struct _ColorARGB {
21     uint8_t blue;
22     uint8_t green;
23     uint8_t red;
24     uint8_t alpha;
25 } ColorARGB;
26 
27 typedef union _Color {
28     uint32_t color;     //0xFFFEED2B    0x2B 0xED 0xFE 0xFF         
29     ColorARGB colorArgb;
30 } Color;
31 
32 int main() {
33 
34     BaseData data;
35     data.ch = 'B';
36     printf("ch_num is %d
", data.ch_num);
37     printf("Length of BaseData is %ld
", sizeof(BaseData));
38 
39 //---------------------------------------------
40     printf("
");
41     printf("Length of Data is %ld
", sizeof(Data));
42 
43 //-----------------------------------------------
44     printf("
");
45     Color c;
46     c.color = 0xFFFEED2B;
47     printf("alpha = 0x%X,red = 0x%X,green = 0x%X,blue = 0x%X.
",c.colorArgb.alpha,c.colorArgb.red,c.colorArgb.green,c.colorArgb.blue);
48 
49     return 0;
50 }

 
転載先:https://www.cnblogs.com/changchou/p/6203305.html