C语言seekdir()函数:设置下回读取目录的位置
相关函数:open, opendir, closedir, rewinddir, telldir, readdir, scandir
头文件:#include <dirent.h>
定义函数:void seekdir(DIR * dir, off_t offset);
函数说明:seekdir()用来设置参数dir 目录流目前的读取位置, 在调用readdir()时便从此新位置开始读取. 参数offset 代表距离目录文件开头的偏移量。
错误代码:EBADF 参数dir 为无效的目录流。
范例
#include <sys/types.h>
#include <dirent.h>
#include <unistd.h>
main()
{
DIR * dir;
struct dirent * ptr;
int offset, offset_5, i = 0;
dir = opendir("/etc/rc.d");
while((ptr = readdir(dir)) != NULL)
{
offset = telldir(dir);
if(++i == 5)
offset_5 = offset;
printf("d_name : %s offset :%d \n", ptr->d_name, offset);
}
seekdir(dir offset_5);
printf("Readdir again!\n");
while((ptr = readdir(dir)) != NULL)
{
offset = telldir(dir);
printf("d_name : %s offset :%d\n", ptr->d_name, offset);
}
closedir(dir);
}
执行:
d_name : . offset :12
d_name : .. offset :24
d_name : init.d offset 40
d_name : rc0.d offset :56
d_name : rc1.d offset :72
d_name : rc2.d offset :88
d_name : rc3.d offset :104
d_name : rc4.d offset :120
d_name : rc5.d offset :136
d_name : rc6.d offset :152
d_name : rc offset :164
d_name : rc.local offset :180
d_name : rc.sysinit offset :4096 readdir again!
d_name : rc2.d offset :88
d_name : rc3.d offset :104
d_name : rc4.d offset :120
d_name : rc5.d offset :136
d_name : rc6.d offset :152
d_name : rc offset :164
d_name : rc.local offset :180
d_name : rc.sysinit offset :4096
头文件:#include <dirent.h>
定义函数:void seekdir(DIR * dir, off_t offset);
函数说明:seekdir()用来设置参数dir 目录流目前的读取位置, 在调用readdir()时便从此新位置开始读取. 参数offset 代表距离目录文件开头的偏移量。
错误代码:EBADF 参数dir 为无效的目录流。
范例
#include <sys/types.h>
#include <dirent.h>
#include <unistd.h>
main()
{
DIR * dir;
struct dirent * ptr;
int offset, offset_5, i = 0;
dir = opendir("/etc/rc.d");
while((ptr = readdir(dir)) != NULL)
{
offset = telldir(dir);
if(++i == 5)
offset_5 = offset;
printf("d_name : %s offset :%d \n", ptr->d_name, offset);
}
seekdir(dir offset_5);
printf("Readdir again!\n");
while((ptr = readdir(dir)) != NULL)
{
offset = telldir(dir);
printf("d_name : %s offset :%d\n", ptr->d_name, offset);
}
closedir(dir);
}
执行:
d_name : . offset :12
d_name : .. offset :24
d_name : init.d offset 40
d_name : rc0.d offset :56
d_name : rc1.d offset :72
d_name : rc2.d offset :88
d_name : rc3.d offset :104
d_name : rc4.d offset :120
d_name : rc5.d offset :136
d_name : rc6.d offset :152
d_name : rc offset :164
d_name : rc.local offset :180
d_name : rc.sysinit offset :4096 readdir again!
d_name : rc2.d offset :88
d_name : rc3.d offset :104
d_name : rc4.d offset :120
d_name : rc5.d offset :136
d_name : rc6.d offset :152
d_name : rc offset :164
d_name : rc.local offset :180
d_name : rc.sysinit offset :4096