linux 目录操作函数opendir readdir closedir，文件stat

#include <sys/types.h>

#include <dirent.h>

DIR *opendir(const char *p a t h n a m e ) ;

返回：若成功则为指针，若出错则为N U L L

struct dirent *readdir(DIR *d p ) ;

返回：若成功则为指针，若在目录尾或出错则为N ULL

int closedir(DIR *d p ) ;

返回：若成功则为0，若出错则为-1

D I R结构是一个内部结构，它由这四个函数用来保存正被读的目录的有关信息。其作用类

似于F I L E结构。由o p e n d i r返回的指向D I R结构的指针由另外三个函数使用。o p e n d i r执行初始化操作，使第

一个r e a d d i r读目录中的第一个目录项。目录中各目录项的顺序与实现有关。它们通常并不按字

母顺序排列。

程序：

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <dirent.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <iostream>

using namespace std;

int main(int argc ,char **argv)

{

DIR *pDir = NULL;

struct dirent *pDirent = NULL;

if((pDir = opendir("./")) == NULL) //读取目录

{

switch (errno)

{

case EACCES:

cout << "Permission denied." << endl;

break;

case EMFILE:

cout << " Too many file descriptors in use by process." << endl;

break;

case ENFILE:

cout << " Too many files are currently open in the system." << endl;

break;

case ENOENT:

cout << " Directory does not exist, or name is an empty string." << endl;

break;

case ENOMEM:

cout << " Insufficient memory to complete the operation." << endl;

break;

case ENOTDIR:

cout << " name is not a directory." << endl;

break;

default:

cout << "unknow error" << endl;

}

return -1;

}

int i = 0;

while(true)

{

i++;

pDirent = readdir(pDir) ; //读取单一文件

if(pDirent == NULL)

{

cout<<i<<"====pdirent is null"<<endl;

break;

}

if ((strcmp((const char *)pDirent->d_name, ".") == 0) ||(strcmp((const char *)pDirent->d_name, "..") == 0))

{

continue;

}

printf("file name:%s\n",pDirent->d_name);

char cNewDir[1024];

memset(cNewDir, 0, sizeof(cNewDir));

sprintf(cNewDir, "%s/%s", "./", (char *)pDirent->d_name);

struct stat mstat;

memset(&mstat,0,sizeof(mstat));

if(lstat(cNewDir,&mstat) == -1) //获取文件属性结构 ，此处需要使用lstat，如使用stat，则不能判断链接文件的信息

{

perror("stat:");

continue;

}

if(S_ISDIR(mstat.st_mode)) //判断是否是目录

{

printf("file:%s is a directory\n",pDirent->d_name);

}

else if(S_ISREG(mstat.st_mode))

{

printf("file:%s is a regular file.\n",pDirent->d_name);

}

else if(S_ISCHR(mstat.st_mode))

{

printf("file:%s is a character special file.\n",pDirent->d_name);

}

else if(S_ISBLK(mstat.st_mode))

{

printf("file:%s is a block file.\n",pDirent->d_name);

}

else if(S_ISFIFO(mstat.st_mode))

{

printf("file:%s is a fifo file.\n",pDirent->d_name);

}

else if(S_ISLNK(mstat.st_mode))

{

printf("file:%s is a symbolic link file.\n",pDirent->d_name);

}

else if(S_ISSOCK(mstat.st_mode))

{

printf("file:%s is a socket file.\n",pDirent->d_name);

}

else

{

printf("file:%s is an unknown type file.\n",pDirent->d_name);

}

}

closedir(pDir);

return 0;

}