递归读取文件夹下所有文件

有时候需要获取一个文件夹下的所有文件，甚至需要获取特定类型的文件。下面介绍两种分别在 Linux 和 Windows下可以运行的程序实现。

---

Linux C

在 Linux 中可以使用 opendir，readdir，closedir 来实现.

函数原型：

int            alphasort(const struct dirent **, const struct dirent **);
int            closedir(DIR *);
int            dirfd(DIR *);
DIR           *fdopendir(int);
DIR           *opendir(const char *);
struct dirent *readdir(DIR *);
int            readdir_r(DIR *restrict, struct dirent *restrict,
                   struct dirent **restrict);
void           rewinddir(DIR *);
int            scandir(const char *, struct dirent ***,
                   int (*)(const struct dirent *),
                   int (*)(const struct dirent **,
                   const struct dirent **));

这些函数都在 dirent.h 头文件中，为了使用这些函数，还需要一个特别重要的结构体 dirent：

struct dirent {
  ino_t  d_ino;  /* Inode number */
  off_t  d_off;  /* Not an offset; see below */
  unsigned short  d_reclen;  /* Length of this record */
  unsigned char  d_type; /* Type of file; not supported by all filesystem types */
  char  d_name[256];  /* Null-terminated filename */
};

主要会用到 d_type 和 d_name，分别表示文件的类型和文件名。

d_type 有这几种可能的值：

DT_BLK      This is a block device.
DT_CHR      This is a character device.
DT_DIR      This is a directory.
DT_FIFO     This is a named pipe (FIFO).
DT_LNK      This is a symbolic link.
DT_REG      This is a regular file.
DT_SOCK     This is a UNIX domain socket.
DT_UNKNOWN  The file type could not be determined.

DIR应该和FILE类似。就不多说了。我们只需要知道opendir失败时会返回NULL就够了。

code

#include <stdio.h>
#include <dirent.h>
#include <string.h>

void findDir(char* path){
    DIR *dir = opendir(path);

    if(dir == NULL){
        printf("open path fail: %s \n", path);
        return;
    }

    struct dirent* ent = NULL;
    while (NULL != (ent = readdir(dir)))
    {        
        if (ent->d_type == DT_REG)
        {
            printf("normal: %s \n", ent->d_name);
        }
        else if(ent->d_type == DT_DIR)
        {
            printf("subdir: %s \n", ent->d_name);
            if( 0!=strcmp(ent->d_name, ".") && 0!=strcmp(ent->d_name, "..") ){
                findDir(ent->d_name);
                printf("end %s \n", ent->d_name);
            }
        }
    }
}

int main(int argc, char * argv[])
{
   char* path = ".";
   findDir(path); 
   return 0;
}

---

Windows C++

code

#include<iostream>
#include<io.h>
#include<string>

using namespace std;

string respath = "*.*";

void displayFile(string path) {
  string st{path + respath};
  std::cout << path << std::endl;
  _finddata_t file;
  intptr_t lf;
  if ((lf = _findfirst(st.c_str(), &file)) == -1)
    cout << "can not find any file!" << std::endl;
  else {
    cout << "file lists:" << std::endl;
    do {
      string str{file.name};
      std::cout << file.name << std::endl;
      if (file.attrib == _A_NORMAL)cout << "  normal  " << std::endl;
      else if (file.attrib == _A_RDONLY)cout << "  read only  " << std::endl;
      else if (file.attrib == _A_HIDDEN)cout << "  hidden  " << std::endl;
      else if (file.attrib == _A_SYSTEM)cout << "  system  " << std::endl;
      else if (file.attrib == _A_SUBDIR) {
        if (strcmp(file.name, ".") == 0 ||
            strcmp(file.name, "..") == 0 || 
            strcmp(file.name, ".svn") == 0 || 
            strcmp(file.name, ".git") == 0) {
          std::cout << "ignore " << file.name << std::endl;
        } else {
          cout << "  subdir  " << file.name << endl;
          string temp{path + file.name + "/"};
          // recursion
          displayFile(temp);
          temp = path;
        }
      } 
    } while (_findnext(lf, &file) == 0);
  }
  _findclose(lf);
}

int main() {
  string path = "D:/images/desk/";

  //_finddata_t file;
  displayFile(path);

  return 0;
}