1 opendir所需的头文件
#include<sys/types.h>
#include<dirent.h>
2函数声明
DIR *opendir(const char *name);
DIR *fdopendir(int fd);
通过opendir来打开一个文件夹
3readdir依赖的头文件
#include<dirent.h>
4函数声明
struct dirent *readdir(DIR *dirp);
int readdir_r(DIR *dirp, struct dirent*entry, struct dirent **result);
函数说明
通过这两个函数实现读取目录
关于struct dirent，定义如下：
struct dirent {
ino_t d_ino; /* inode number */
off_t d_off; /* not an offset; see NOTES */
unsignedshort d_reclen; /* length of this record*/
unsigned char d_type; /* typeof file; not supported
by all filesystem 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
6.rewinddir
#include <sys/types.h>
#include <dirent.h>
void rewinddir(DIR *dirp);
把目录指针恢复到目录的起始位置。
7.telldir/seekdir
#include <dirent.h>
long telldir(DIR *dirp);
#include <dirent.h>
void seekdir(DIR *dirp, long offset);
函数描述
telldir - return current location indirectory stream
The telldir() function returns the current location associated with
the directory stream dirp.
8.closedir
#include<sys/types.h>
#include<dirent.h>
int closedir(DIR*dirp);
函数描述
The closedir() function closes the directory stream associated with
dirp. A successful call to closedir() also closes the underlying
file descriptor associated with dirp. The directory stream descrip‐
tor dirp is not available after thiscall.
9.通过递归的方式遍历目录
#include<sys/types.h>
#include<sys/stat.h>
#include<unistd.h>
#include<dirent.h>
#include<stdio.h>
#include<string.h>
#define MAX_PATH1024
/* dirwalk: applyfcn to all files in dir */
void dirwalk(char*dir, void (*fcn)(char *))
{
char name[MAX_PATH];
struct dirent *dp;
DIR *dfd;
if ((dfd = opendir(dir)) == NULL) {
fprintf(stderr, "dirwalk: can't open%s\n", dir);
return;
}
while ((dp = readdir(dfd)) != NULL) {
if (strcmp(dp->d_name, ".") ==0
|| strcmp(dp->d_name, "..") ==0)
continue; /* skip self and parent */
if (strlen(dir)+strlen(dp->d_name)+2> sizeof(name))
fprintf(stderr, "dirwalk: name %s %stoo long\n",
dir, dp->d_name);
else {
sprintf(name, "%s/%s", dir,dp->d_name);
(*fcn)(name);
}
}
closedir(dfd);
}
/* fsize: printthe size and name of file "name" */
void fsize(char*name)
{
struct stat stbuf;
if (stat(name, &stbuf) == -1) {
fprintf(stderr, "fsize: can't access%s\n", name);
return;
}
if ((stbuf.st_mode & S_IFMT) ==S_IFDIR)
dirwalk(name, fsize);
printf("%8ld %s\n",stbuf.st_size, name);
}
int main(intargc, char **argv)
{
if (argc == 1) /* default: currentdirectory */
fsize(".");
else
while (--argc > 0)
fsize(*++argv);
return 0;
}
这个程序还是不如ls -R健壮，它有可能死循环，思考一下什么情况会导致死循
环。
