19 阵列的复制

 1 // 阵列的复制代价很大，不是一个=赋值就可以的  ,得逐个元素复制过来
 2 
 3 #include<stdio.h>
 4 #include<stdlib.h>
 5 #include<time.h>
 6 
 7 int main()
 8 {
 9     srand(time(0));
10     int i, n[10], v[10];
11     for (i = 0; i < 10; i++) {
12         n[i] = rand() % 100; // 在0-99之间随机取10个数
13 
14     }
15     for (i = 0; i < 10; i++) {
16         v[i] = n[i];
17 
18     }
19     for (i = 0; i < 10; i++) {
20         printf("%d ", n[i]);
21 
22     }
23     printf("
");
24     for (i = 0; i < 10; i++) {
25         printf("%d ", v[i]);
26     }
27     printf("
");
28     return 0;
29 }
30 
31 47 96 20 91 15 98 89 9 22 85
32 47 96 20 91 15 98 89 9 22 85
33 
34 Process returned 0 (0x0)   execution time : 15.246 s
35 Press any key to continue.

用呼叫函式印出两个阵列

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<time.h>
 4 
 5 void printArray(int [10]);
 6 
 7 int main()
 8 {
 9     srand(time(0));
10     int i, n[10], v[10];
11     for (i = 0; i < 10; i++) {
12         n[i] = rand() % 100;
13     }
14     for (i = 0; i < 10; i++) {
15         v[i] = n[i]; // 复制
16     }
17     printArray(n);
18     printArray(v);
19     return 0;
20 
21 }
22 
23 void printArray(int t[10]) {
24      int i;
25      for (i = 0; i < 10; i++) {
26         printf(" %d", t[i]);
27      }
28      printf("
");
29 }
30 
31  36 95 2 25 69 21 14 85 12 15
32  36 95 2 25 69 21 14 85 12 15
33 
34 Process returned 0 (0x0)   execution time : 2.709 s
35 Press any key to continue.

阵列呼叫函式与其他个别呼叫的区别：

阵列呼叫函式后，对函式内改变后，改变的是其本尊.

一般整数呼叫后，没有改变.

 1 // 阵列呼叫函式与其他呼叫函数区别
 2 
 3 #include <stdio.h>
 4 void increase (int [3]);
 5 
 6 int main() {
 7     int i, n[3] = {1, 2, 3};
 8     increase(n);
 9     for (i = 0; i < 3; i++) {
10         printf("n[%d] = %d
", i, n[i]);
11     }
12     return 0;
13 }
14 
15 void increase(int n[3]) {
16      int i;
17      for (i = 0; i < 3; i++) {
18         n[i]++;
19      }
20 }
21 
22 n[0] = 2
23 n[1] = 3
24 n[2] = 4
25 
26 Process returned 0 (0x0)   execution time : 10.484 s
27 Press any key to continue.
28 
29 
30 #include<stdio.h>
31 
32 void increase(int);
33 
34 int main() {
35     int n = 1;
36     increase(n);
37     printf("n = %d
", n);
38     return 0;
39 
40 }
41 
42 void increase(int n) {
43      n++;
44 }
45 
46 n = 1
47 
48 Process returned 0 (0x0)   execution time : 6.315 s
49 Press any key to continue.

19.4sizeof 运算子

资料型别占用的记忆体空间大小大多是属于实作定义，会随着编译器与设定上的不同有所差异

sizeof运算结果为size_t 型别（在printf时使用zu）：我的编译器用%zu无法解读出来，这里我用%d代替，可见在引用函式与没有引用函式数组大小与长度结果是不一样的

 1 #include <stdio.h>
 2 
 3 void f(int[]);
 4 
 5 int main() {
 6     int v[5] = {1, 2, 3, 4, 5};
 7     f(v);
 8     return 0;
 9 }
10 
11 void f(int v[]) {
12     printf("Size of int: %d
", sizeof(int));
13     printf("Size of v[0]: %d
", sizeof(v[0]));
14     printf("Size of v: %d
", sizeof(v));
15     printf("Length of v: %d
", sizeof(v)/sizeof(v[0]));
16 }
17 
18 Size of int: 4
19 Size of v[0]: 4
20 Size of v: 4
21 Length of v: 1
22 
23 Process returned 0 (0x0)   execution time : 5.493 s
24 Press any key to continue.
25 
26 #include <stdio.h>
27 
28 int main() {
29     int v[5] = {1, 2, 3, 4, 5};
30     printf("Size of int: %d
", sizeof(int));
31     printf("Size of v[0]: %d
", sizeof(v[0]));
32     printf("Size of  v: %d
", sizeof(v));
33     printf("Length of v: %d
", sizeof(v)/sizeof(v[0]));
34     return 0;
35 
36 }
37 
38 Size of int: 4
39 Size of v[0]: 4
40 Size of  v: 20
41 Length of v: 5
42 
43 Process returned 0 (0x0)   execution time : 0.998 s
44 Press any key to continue.

19.2 可对任意大小的阵列求最大值

发现：maxv（a, N）中 N要与数组个数一致

 1 #include <stdio.h>
 2 
 3 int maxv(int[], int N);
 4 
 5 int main() {
 6     int a[3] = {3, 9, 7};
 7     printf("Max: %d
", maxv(a, 3));
 8     int b[5] = {3, 4, 1, 2, 7};
 9     printf("Max: %d
", maxv(b, 5));
10     return 0;
11 
12 }
13 
14 int maxv(int v[], int N) {
15     int max = v[0], i;
16     for (i = 1; i < N; i++) {
17         if (v[i] > max)
18         {
19             max = v[i];
20     }
21         }
22 
23     return max;
24 }
25 
26 Max: 9
27 Max: 7
28 
29 Process returned 0 (0x0)   execution time : 0.965 s
30 Press any key to continue.