How can I get the list of files in a directory using C or C++?

user_39036 0
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How can I determine the list of files in a directory from inside my C or C++ code?

I'm not allowed to execute the ls command and parse the results from within my program.

directory c file c++
32 Answers

UPDATE 2017:

In C++17 there is now an official way to list files of your file system: std::filesystem. There is an excellent answer from Shreevardhan below with this source code:

#include <string>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;

int main()
{
    std::string path = "/path/to/directory";
    for (const auto & entry : fs::directory_iterator(path))
        std::cout << entry.path() << std::endl;
}

Old Answer:

In small and simple tasks I do not use boost, I use dirent.h. It is available as a standard header in UNIX, and also available for Windows via a compatibility layer created by Toni Ronkko.

DIR *dir;
struct dirent *ent;
if ((dir = opendir ("c:\\src\\")) != NULL) {
  /* print all the files and directories within directory */
  while ((ent = readdir (dir)) != NULL) {
    printf ("%s\n", ent->d_name);
  }
  closedir (dir);
} else {
  /* could not open directory */
  perror ("");
  return EXIT_FAILURE;
}

It is just a small header file and does most of the simple stuff you need without using a big template-based approach like boost (no offence, I like boost!).

Peter_Parker_232640

Unfortunately the C++ standard does not define a standard way of working with files and folders in this way.

Since there is no cross platform way, the best cross platform way is to use a library such as the boost filesystem module.

Cross platform boost method:

The following function, given a directory path and a file name, recursively searches the directory and its sub-directories for the file name, returning a bool, and if successful, the path to the file that was found. 

bool find_file(const path & dir_path,         // in this directory,
               const std::string & file_name, // search for this name,
               path & path_found)             // placing path here if found
{
    if (!exists(dir_path)) 
        return false;

    directory_iterator end_itr; // default construction yields past-the-end

    for (directory_iterator itr(dir_path); itr != end_itr; ++itr)
    {
        if (is_directory(itr->status()))
        {
            if (find_file(itr->path(), file_name, path_found)) 
                return true;
        }
        else if (itr->leaf() == file_name) // see below
        {
            path_found = itr->path();
            return true;
        }
    }
    return false;
}

Source from the boost page mentioned above.

For Unix/Linux based systems:

You can use opendir / readdir / closedir.

Sample code which searches a directory for entry ``name'' is:

len = strlen(name);
dirp = opendir(".");
while ((dp = readdir(dirp)) != NULL)
        if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
                (void)closedir(dirp);
                return FOUND;
        }
(void)closedir(dirp);
return NOT_FOUND;

Source code from the above man pages.

For a windows based systems:

You can use the Win32 API FindFirstFile / FindNextFile / FindClose functions.

The following C++ example shows you a minimal use of FindFirstFile.

#include <windows.h>
#include <tchar.h>
#include <stdio.h>

void _tmain(int argc, TCHAR *argv[])
{
   WIN32_FIND_DATA FindFileData;
   HANDLE hFind;

   if( argc != 2 )
   {
      _tprintf(TEXT("Usage: %s [target_file]\n"), argv[0]);
      return;
   }

   _tprintf (TEXT("Target file is %s\n"), argv[1]);
   hFind = FindFirstFile(argv[1], &FindFileData);
   if (hFind == INVALID_HANDLE_VALUE) 
   {
      printf ("FindFirstFile failed (%d)\n", GetLastError());
      return;
   } 
   else 
   {
      _tprintf (TEXT("The first file found is %s\n"), 
                FindFileData.cFileName);
      FindClose(hFind);
   }
}

Source code from the above msdn pages.

Brian_R_Bondy_31530
user_107550 
char **getKeys(char *data_dir, char* tablename, int *num_keys)
{
    char** arr = malloc(MAX_RECORDS_PER_TABLE*sizeof(char*));
int i = 0;
for (;i < MAX_RECORDS_PER_TABLE; i++)
    arr[i] = malloc( (MAX_KEY_LEN+1) * sizeof(char) );  


char *buf = (char *)malloc( (MAX_KEY_LEN+1)*sizeof(char) );
snprintf(buf, MAX_KEY_LEN+1, "%s/%s", data_dir, tablename);

DIR* tableDir = opendir(buf);
struct dirent* getInfo;

readdir(tableDir); // ignore '.'
readdir(tableDir); // ignore '..'

i = 0;
while(1)
{


    getInfo = readdir(tableDir);
    if (getInfo == 0)
        break;
    strcpy(arr[i++], getInfo->d_name);
}
*(num_keys) = i;
return arr;
}
user_13018980 
#include <string>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;

int main() {
    std::string path = "/path/to/directory";
    for (const auto & entry : fs::directory_iterator(path))
        std::cout << entry.path() << std::endl;
}
user_134191410

you can get all direct of files in your root directory by using std::experimental:: filesystem::directory_iterator(). Then, read the name of these pathfiles.

#include <iostream>
#include <filesystem>
#include <string>
#include <direct.h>
using namespace std;
namespace fs = std::experimental::filesystem;
void ShowListFile(string path)
{
for(auto &p: fs::directory_iterator(path))  /*get directory */
     cout<<p.path().filename()<<endl;   // get file name
}

int main() {

ShowListFile("C:/Users/dell/Pictures/Camera Roll/");
getchar();
return 0;
}
user_96761140

This answer should work for Windows users that have had trouble getting this working with Visual Studio with any of the other answers.

  1. Download the dirent.h file from the github page. But is better to just use the Raw dirent.h file and follow my steps below (it is how I got it to work).

    Github page for dirent.h for Windows: Github page for dirent.h

    Raw Dirent File: Raw dirent.h File

  2. Go to your project and Add a new Item (Ctrl+Shift+A). Add a header file (.h) and name it dirent.h.

  3. Paste the Raw dirent.h File code into your header.

  4. Include "dirent.h" in your code.

  5. Put the below void filefinder() method in your code and call it from your main function or edit the function how you want to use it.

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

string path = "C:/folder"; //Put a valid path here for folder

void filefinder()
{
    DIR *directory = opendir(path.c_str());
    struct dirent *direntStruct;

    if (directory != NULL) {
        while (direntStruct = readdir(directory)) {
            printf("File Name: %s\n", direntStruct->d_name); //If you are using <stdio.h>
            //std::cout << direntStruct->d_name << std::endl; //If you are using <iostream>
        }
    }
    closedir(directory);
}
user_100925470

I tried to follow the example given in both answers and it might be worth noting that it appears as though std::filesystem::directory_entry has been changed to not have an overload of the << operator. Instead of std::cout << p << std::endl; I had to use the following to be able to compile and get it working:

#include <iostream>
#include <filesystem>
#include <string>
namespace fs = std::filesystem;

int main() {
    std::string path = "/path/to/directory";
    for(const auto& p : fs::directory_iterator(path))
        std::cout << p.path() << std::endl;
}

trying to pass p on its own to std::cout << resulted in a missing overload error.

user_53735090

Building on what herohuyongtao posted and a few other posts:

http://www.cplusplus.com/forum/general/39766/

What is the expected input type of FindFirstFile?

How to convert wstring into string?

This is a Windows solution.

Since I wanted to pass in std::string and return a vector of strings I had to make a couple conversions.

#include <string>
#include <Windows.h>
#include <vector>
#include <locale>
#include <codecvt>

std::vector<std::string> listFilesInDir(std::string path)
{
    std::vector<std::string> names;
    //Convert string to wstring
    std::wstring search_path = std::wstring_convert<std::codecvt_utf8<wchar_t>>().from_bytes(path);
    WIN32_FIND_DATA fd;
    HANDLE hFind = FindFirstFile(search_path.c_str(), &fd);
    if (hFind != INVALID_HANDLE_VALUE) 
    {
        do 
        {
            // read all (real) files in current folder
            // , delete '!' read other 2 default folder . and ..
            if (!(fd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) 
            {
                //convert from wide char to narrow char array
                char ch[260];
                char DefChar = ' ';
                WideCharToMultiByte(CP_ACP, 0, fd.cFileName, -1, ch, 260, &DefChar, NULL);
                names.push_back(ch);
            }
        } 
        while (::FindNextFile(hFind, &fd));
        ::FindClose(hFind);
    }
    return names;
}
user_15412690

Simply in Linux use following ASCI C style code

#include <bits/stdc++.h>
#include <dirent.h>
using namespace std;

int main(){
    DIR *dpdf;
    struct dirent *epdf;
    dpdf = opendir("./");
    
    if (dpdf != NULL){
    while (epdf = readdir(dpdf)){
        cout << epdf->d_name << std::endl;
    }
    }
    closedir(dpdf);
    return 0;
}

Hope this helps!

user_125464750

Just something that I want to share and thank you for the reading material. Play around with the function for a bit to understand it. You may like it. e stood for extension, p is for path, and s is for path separator.

If the path is passed without ending separator, a separator will be appended to the path. For the extension, if an empty string is inputted then the function will return any file that does not have an extension in its name. If a single star was inputted than all files in the directory will be returned. If e length is greater than 0 but is not a single * then a dot will be prepended to e if e had not contained a dot at the zero position.

For a returning value. If a zero-length map is returned then nothing was found but the directory was open okay. If index 999 is available from the return value but the map size is only 1 then that meant there was a problem with opening the directory path.

Note that for efficiency, this function can be split into 3 smaller functions. On top of that, you can create a caller function that will detect which function it is going to call based on the input. Why is that more efficient? Said if you are going to grab everything that is a file, doing that method the subfunction that built for grabbing all the files will just grab all that are files and does not need to evaluate any other unnecessary condition everytime it found a file.

That would also apply to when you grab files that do not have an extension. A specific built function for that purpose would only evaluate for weather if the object found is a file and then whether or not if the name of the file has a dot in it.

The saving may not be much if you only read directories with not so much files. But if you are reading a mass amount of directory or if the directory has couple hundred thousands of files, it could be a huge saving.

#include <stdio.h>
#include <sys/stat.h>
#include <iostream>
#include <dirent.h>
#include <map>

std::map<int, std::string> getFile(std::string p, std::string e = "", unsigned char s = '/'){
    if ( p.size() > 0 ){
        if (p.back() != s) p += s;
    }
    if ( e.size() > 0 ){
        if ( e.at(0) != '.' && !(e.size() == 1 && e.at(0) == '*') ) e = "." + e;
    }

    DIR *dir;
    struct dirent *ent;
    struct stat sb;
    std::map<int, std::string> r = {{999, "FAILED"}};
    std::string temp;
    int f = 0;
    bool fd;

    if ( (dir = opendir(p.c_str())) != NULL ){
        r.erase (999);
        while ((ent = readdir (dir)) != NULL){
            temp = ent->d_name;
            fd = temp.find(".") != std::string::npos? true : false;
            temp = p + temp;

            if (stat(temp.c_str(), &sb) == 0 && S_ISREG(sb.st_mode)){
                if ( e.size() == 1 && e.at(0) == '*' ){
                    r[f] = temp;
                    f++;
                } else {
                    if (e.size() == 0){
                        if ( fd == false ){
                            r[f] = temp;
                            f++;
                        }
                        continue;
                    }

                    if (e.size() > temp.size()) continue;

                    if ( temp.substr(temp.size() - e.size()) == e ){
                        r[f] = temp;
                        f++;
                    }
                }
            }
        }

        closedir(dir);
        return r;
    } else {
        return r;
    }
}

void printMap(auto &m){
    for (const auto &p : m) {
        std::cout << "m[" << p.first << "] = " << p.second << std::endl;
    }
}

int main(){
    std::map<int, std::string> k = getFile("./", "");
    printMap(k);
    return 0;
}
user_74497060 
#include<iostream>
#include <dirent.h>
using namespace std;
char ROOT[]={'.'};

void listfiles(char* path){
    DIR * dirp = opendir(path);
    dirent * dp;
    while ( (dp = readdir(dirp)) !=NULL ) {
         cout << dp->d_name << " size " << dp->d_reclen<<std::endl;
    }
    (void)closedir(dirp);
}

int main(int argc, char **argv)
{
    char* path;
    if (argc>1) path=argv[1]; else path=ROOT;

    cout<<"list files in ["<<path<<"]"<<std::endl;
    listfiles(path);

    return 0;
}
user_16107780
user_143479800

Based on the answers above

#include <vector>
#include <string>
#include <algorithm>

#ifdef _WIN32
#include <windows.h>
std::vector<std::string> files_in_directory(std::string path)
{
    std::vector<std::string> files;

    // check directory exists
    char fullpath[MAX_PATH];
    GetFullPathName(path.c_str(), MAX_PATH, fullpath, 0);
    std::string fp(fullpath);
    if (GetFileAttributes(fp.c_str()) != FILE_ATTRIBUTE_DIRECTORY)
        return files;

    // get file names
    WIN32_FIND_DATA findfiledata;
    HANDLE hFind = FindFirstFile((LPCSTR)(fp + "\\*").c_str(), &findfiledata);
    if (hFind != INVALID_HANDLE_VALUE)
    {
        do 
        {
            files.push_back(findfiledata.cFileName);
        } 
        while (FindNextFile(hFind, &findfiledata));
        FindClose(hFind);
    }

    // delete current and parent directories
    files.erase(std::find(files.begin(), files.end(), "."));
    files.erase(std::find(files.begin(), files.end(), ".."));

    // sort in alphabetical order
    std::sort(files.begin(), files.end());

    return files;
}
#else
#include <dirent.h>
std::vector<std::string> files_in_directory(std::string directory)
{
    std::vector<std::string> files;

    // open directory
    DIR *dir;
    dir = opendir(directory.c_str());
    if (dir == NULL)
        return files;

    // get file names
    struct dirent *ent;
    while ((ent = readdir(dir)) != NULL)
        files.push_back(ent->d_name);
    closedir(dir);

    // delete current and parent directories
    files.erase(std::find(files.begin(), files.end(), "."));
    files.erase(std::find(files.begin(), files.end(), ".."));

    // sort in alphabetical order
    std::sort(files.begin(), files.end());

    return files;
}
#endif  // _WIN32
user_124477660

Shreevardhan's design also works great for traversing subdirectories:

#include <string>
#include <iostream>
#include <filesystem>

using namespace std;
namespace fs = filesystem;
int main()
{
    string path = "\\path\\to\\directory";
    // string path = "/path/to/directory";
    for (auto & p : fs::recursive_directory_iterator(path))
        cout << p.path() << endl;
}

Compilation: cl /EHsc /W4 /WX /std:c++17 ListFiles.cpp

user_174301450

Contribution to Cesar Alejandro Montero Orozco answer.

There is beauty in simplicity, and by adding the /s key, we also go through subdirectories.

system("dir /n /b /s * > file_names.txt");
user_174301450
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