linux下大文件读写源码示例

#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE
#define _FILE_OFFSET_BITS 64
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
int main()
{
printf("sizeof(off_t) = %d\n", sizeof(off_t));
int fd = 0;
#if 1
fd = open("/root/test", O_WRONLY | O_CREAT | O_LARGEFILE, 0600);
#else
fd = open("/dev/hda1", O_RDONLY, 0600);
#endif
if (fd > 0)
{
off_t l = 0x200000001LL;
off_t l_new = lseek(fd, l, SEEK_SET);
if (l_new < 0)
printf("l_new =%d\n", l_new);
#if 1
else
write(fd, &fd, sizeof(fd));
#endif
printf("l_new = 0x%.16x\n", l_new);
close(fd);
}
struct stat st;
int ret = stat( "/root/test", &st);
printf( "\n%d--%I64u-\n", ret, st.st_size );
}