C語言中使用struct實現數組復制

在C語言中，直接在參數中聲明數組變量是無法實現傳值傳參的，這時只會把數組的首地址傳過去。將數組放置到一個struct中進行傳參，可以實現傳值的方式。例如下面的程序：

[cpp]

1. #include <stdio.h>
3. struct tag {int a[100]};
4. struct tag orange, lime, lemon;
6. struct tag twofold(struct tag s){
7. int i;
8. for(i=0; i<100; i++){
9. s.a[i] *= 2;
10. }
11. return s;
12. }
14. int main(){
15. int i;
16. for(i=0; i<100; i++){ orange.a[i] = 1; }
17. lime = twofold(orange);
18. for(i=0; i<10; i++){
19. printf("before: lime.a[%d] = %d\n", i, lime.a[i]);
20. }
21. lemon = lime;
22. for(i=0; i<100; i++){ lemon.a[i] = 7; }
24. for(i=0; i<10; i++){
25. printf("lemon.a[%d] = %d\n", i, lemon.a[i]);
26. }
28. for(i=0; i<10; i++){
29. printf("after: lime.a[%d] = %d\n", i, lime.a[i]);
30. }
31. }

[java]

1. before: lime.a[0] = 2
2. before: lime.a[1] = 2
3. before: lime.a[2] = 2
4. before: lime.a[3] = 2
5. before: lime.a[4] = 2
6. before: lime.a[5] = 2
7. before: lime.a[6] = 2
8. before: lime.a[7] = 2
9. before: lime.a[8] = 2
10. before: lime.a[9] = 2
11. lemon.a[0] = 7
12. lemon.a[1] = 7
13. lemon.a[2] = 7
14. lemon.a[3] = 7
15. lemon.a[4] = 7
16. lemon.a[5] = 7
17. lemon.a[6] = 7
18. lemon.a[7] = 7
19. lemon.a[8] = 7
20. lemon.a[9] = 7
21. after: lime.a[0] = 2
22. after: lime.a[1] = 2
23. after: lime.a[2] = 2
24. after: lime.a[3] = 2
25. after: lime.a[4] = 2
26. after: lime.a[5] = 2
27. after: lime.a[6] = 2
28. after: lime.a[7] = 2
29. after: lime.a[8] = 2
30. after: lime.a[9] = 2