第 16 章 C 预处理器和 C 库（string.h 库中的 m…

 1 /*-----------------------------------------
 2     mems.c -- 使用 memcpy() 和 memmove()
 3 -----------------------------------------*/
 4 
 5 #include <stdio.h>
 6 #include <string.h>
 7 #include <stdlib.h>
 8 
 9 #define SIZE 10
10 
11 void show_array(const int ar[], int n);
12 
13 int main()
14 {
15     int values[SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
16     int target[SIZE];
17     double curious[SIZE / 2] = {2.0, 2.0e5, 2.0e10, 2.0e20, 2.0e30};
18 
19     puts("memcpy() used:");
20     fputs("values (original data):\n", stdout);        //等同于 puts("values (original data):");
21     show_array(values, SIZE);
22     memcpy(target, values, SIZE * sizeof(int));
23     puts("target (copy of values):");
24     show_array(target, SIZE);
25 
26     puts("\nUsing memmove() with overlapping ranges:");
27     memmove(values + 2, values, (SIZE / 2) * sizeof(int));
28     puts("values -- elements 0-4 copied to 2-6:");
29     show_array(values, SIZE);
30 
31     puts("\nUsing memcpy() to copy double to int:");
32     memcpy(target, curious, (SIZE / 2) * sizeof(double));
33     puts("target -- 5 double into 10 int positions:");
34     show_array(target, SIZE / 2);
35     show_array(target + 5, SIZE / 2);
36 
37     return 0;
38 }
39 
40 void show_array(const int ar[], int n)
41 {
42     for (int index = 0; index != n; ++index)
43         printf("%d ", ar[index]);
44 
45     fputc('\n', stdout);
46 }