#include <sys/stat.h>
#include <sys/types.h>

int mkdir(const char *pathname, mode_t mode);

//rmdir 删除文件夹

#include <unistd.h>
int rmdir(const char *pathname);

//dopendir/fdopendir  //打开文件夹

DIR是一个结构体，是一个内部结构，用来存储读取文件夹的相关信息。

DIR *opendir(const char *name);
DIR *fdopendir(int fd);

#include <dirent.h>
struct dirent *readdir(DIR *dirp);

struct dirent {
    ino_t d_ino; /* inode number */
    off_t d_off; /* offset to the next dirent */
    unsigned short d_reclen; /* length of this record */
    unsigned char d_type; /* type of file; not supportedby all file system types */
    char d_name[256]; /* filename */
};

readdir 每次返回一条记录项。。DIR*指针指向下一条记录项。

#include <sys/types.h>
#include <dirent.h>

void rewinddir(DIR *dirp);

把文件夹指针恢复到文件夹的起始位置。

//telldir函数

 #include <dirent.h>

 long telldir(DIR *dirp);

函数返回值是为文件夹流的当前位置，表示文件夹文件距开头的偏移量。

//seekdir

#include <dirent.h>
void seekdir(DIR *dirp, long offset);

//closedir 关闭文件夹流

 #include <sys/types.h>
 #include <dirent.h>

 int closedir(DIR *dirp);

使用递归来遍历文件夹下的文件

#include<stdio.h>
#include <errno.h>
#include<stdlib.h>
#include<string.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#define MAX_PATH 512

void print_file_info(char *pathname);
void dir_order(char *pathname);

void dir_order(char *pathname)
{
	DIR *dfd;
	char name[MAX_PATH];
	struct dirent *dp;
	if ((dfd = opendir(pathname)) == NULL)
	{
		printf("dir_order: can‘t open %s\n %s", pathname,strerror(errno));
		return;
	}
	while ((dp = readdir(dfd)) != NULL)
	{
		if (strncmp(dp->d_name, ".", 1) == 0)
			continue; /* 跳过当前文件夹和上一层文件夹以及隐藏文件*/
		if (strlen(pathname) + strlen(dp->d_name) + 2 > sizeof(name))
		{
			printf("dir_order: name %s %s too long\n", pathname, dp->d_name);
		} else
		{
			memset(name, 0, sizeof(name));
			sprintf(name, "%s/%s", pathname, dp->d_name);
			print_file_info(name);
		}
	}
	closedir(dfd);

}
void print_file_info(char *pathname)
{
	struct stat filestat;
	if (stat(pathname, &filestat) == -1)
	{
		printf("cannot access the file %s", pathname);
		return;
	}
	if ((filestat.st_mode & S_IFMT) == S_IFDIR)
	{
		dir_order(pathname);
	}
	printf("%s %8ld\n", pathname, filestat.st_size);
}
int main(int argc, char *argv[])
{
	if (argc == 1)
	{
		dir_order(".");
	} else
	{
		dir_order(argv[1]);
	}
	return 0;
}