linux实现复制文件的两种方法

1. #include <stdio.h>
2. #include <sys/types.h>
3. #include <sys/stat.h>
4. #include <fcntl.h>
5. #include <unistd.h>
6. #include <time.h> 
7. #define N 32
8. 
9. int main(int argc, const char *argv[])
10. {
11.   clock_t start, end;
12.   double cpu_time_used;
13.   start = clock();
14. 
15.   int fd_r = open(argv[1], O_RDONLY);
16.   if(fd_r == -1)
17.   {
18.     printf("open error\n");
19.     return -1;
20.   }
21. 
22.   int fd_w = open(argv[2], O_RDWR|O_CREAT|O_TRUNC, 0664);
23.   if(fd_w == -1)
24.   {
25.     printf("open error\n");
26.     return -1;
27.   }
28. 
29.   char buf[N];
30.   int ret = 0;
31. 
32.   while((ret = read(fd_r, buf, N)) > 0)
33.   {
34.     write(fd_w, buf, ret);
35.   }
36.   printf("copy ok\n");
37. 
38.   close(fd_r);
39.   close(fd_w);
40. 
41.   end = clock();
42.   cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
43. 
44. printf("运行时间：%d s",cpu_time_used);
45.   return 0;
46. }

1. //使用fgetc、fputc完成文件的拷贝操作
2. #include <stdio.h>
3. #include <time.h>
4. 
5. int main(int argc, const char *argv[])
6. {
7. clock_t start, end;
8. double cpu_time_used;
9.         start = clock();
10. 
11. if(argc < 3)
12.         {
13. printf("Usage : %s <src_file> <dst_file>\n", argv[0]);
14. return -1;
15.         }
16. 
17.         FILE *fp_r = fopen(argv[1], "r");
18. if(fp_r == NULL)
19.         {
20. printf("fp_r fopen error\n");
21. return -1;
22.         }
23. 
24.         FILE *fp_w = fopen(argv[2], "w");
25. if(fp_w == NULL)
26.         {
27. printf("fp_w fopen error\n");
28. return -1;
29.         }
30. 
31. int ret = 0;
32. 
33. while((ret = fgetc(fp_r)) != EOF)
34.         {
35. fputc(ret, fp_w);
36.         }
37. printf("copy ok\n");
38. 
39. fclose(fp_r);
40. fclose(fp_w);
41. 
42.         end = clock();
43.         cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
44. 
45. printf("运行时间：%d s",cpu_time_used);
46. return 0;
47. }