structures in c

c语言结构体，以前没仔细看，原来对其理解不够。

C++语言: Codee#25801

01 #include <stdio.h>
02
03 struct point
04 {
05     int x;
06     int y;
07     float unknown;
08 };
09
10 struct rect
11 {
12     struct point pt1;
13     struct point pt2;
14 };
15
16 struct point makepoint(int x, int y)
17 {
18     struct point temp;
19
20     temp.x = x;
21     temp.y = y;
22     return temp;
23 }
24
25 struct point addpoint(struct point p1,
26                       struct point p2)
27 {
28     p1.x += p2.x;
29     p1.y += p2.y;
30
31     return p1;
32 }
33
34 int main()
35 {
36     /*
37     the only legal operations on a structure are copying it
38     or assigning to it as a unit ,
39     taking its addresss with & ,and accessing its member
40     */
41     struct point pt = makepoint(9, 9);
42     struct point pt1 = {1, 1};
43     struct point ans = addpoint(pt, pt1); // attention
44     struct point test = ans;                // attention
45
46     printf("%d %d\n", test.x, test.y);
47
48     return 0;
49 }