How do you iterate through every file directory recursively in standard C

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If you are on Windows  you can use the FindFirstFile together with FindNextFile API  You can use FindFileData dwFileAttributes to check if a given path is a file or a directory  If it s a directory  you can recursively repeat the algorithm   Here  I have put together some code that lists all the files on a Windows machine   http   dreams-soft com projects traverse-directory

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File tree walk ftw is a recursive way to wall the whole directory tree in the path  More details are here  NOTE   You can also use fts that can skip hidden files like   or    or  bashrc  include  lt ftw h gt   include  lt stdio h gt   include  lt sys stat h gt   include  lt string h gt     int list const char  name  const struct stat  status  int type         if  type    FTW NS                  return 0               if  type    FTW F                  printf  quot 0 3o t s n quot   status- gt st mode amp 0777  name                if  type    FTW D  amp  amp  strcmp  quot   quot   name     0                  printf  quot 0 3o t s  n quot   status- gt st mode amp 0777  name               return 0     int main int argc  char  argv           if argc    1                  ftw  quot   quot   list  1               else                 ftw argv 1   list  1                return 0     output looks like following  0755      Shivaji  0644      Shivaji 20200516 204454 png 0644      Shivaji 20200527 160408 png 0644      Shivaji 20200527 160352 png 0644      Shivaji 20200520 174754 png 0644      Shivaji 20200520 180103 png 0755      Saif  0644      Saif Snapchat-1751229005 jpg 0644      Saif Snapchat-1356123194 jpg 0644      Saif Snapchat-613911286 jpg 0644      Saif Snapchat-107742096 jpg 0755      Milind  0644      Milind IMG 1828 JPG 0644      Milind IMG 1839 JPG 0644      Milind IMG 1825 JPG 0644      Milind IMG 1831 JPG 0644      Milind IMG 1840 JPG  Let us say if you want to match a filename  example  searching for all the   jpg    jpeg    png files   for a specific needs  use fnmatch    include  lt ftw h gt    include  lt stdio h gt    include  lt sys stat h gt    include  lt iostream gt    include  lt fnmatch h gt    static const char  filters             quot   jpg quot    quot   jpeg quot    quot   png quot        int list const char  name  const struct stat  status  int type          if  type    FTW NS                  return 0               if  type    FTW F                  int i           for  i   0  i  lt  sizeof filters    sizeof filters 0    i                      if the filename matches the filter                  if  fnmatch filters i   name  FNM CASEFOLD     0                     printf  quot 0 3o t s n quot   status- gt st mode amp 0777  name                    break                                         if  type    FTW D  amp  amp  strcmp  quot   quot   name     0                    printf  quot 0 3o t s  n quot   status- gt st mode amp 0777  name               return 0       int main int argc  char  argv            if argc    1                  ftw  quot   quot   list  1               else                 ftw argv 1   list  1                return 0

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You need to call OS-specific functions for filesystem traversal  like open   and readdir    The C standard does not specify any filesystem-related functions

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We are in 2019  We have filesystem standard library in C    The Filesystem library provides facilities for performing operations on file systems and their components  such as paths  regular files  and directories   There is an important note on this link if you are considering portability issues  It says      The filesystem library facilities may be unavailable if a hierarchical file system is not accessible to the implementation  or if it does not provide the necessary capabilities  Some features may not be available if they are not supported by the underlying file system  e g  the FAT filesystem lacks symbolic links and forbids multiple hardlinks   In those cases  errors must be reported    The filesystem library was originally developed as boost filesystem  was published as the technical specification ISO IEC TS 18822 2015  and finally merged to ISO C   as of C  17  The boost implementation is currently available on more compilers and platforms than the C  17 library    adi-shavit has answered this question when it was part of std  experimental and he has updated this answer in 2017  I want to give more details about the library and show more detailed example   std  filesystem  recursive directory iterator is an LegacyInputIterator that iterates over the directory entry elements of a directory  and  recursively  over the entries of all subdirectories  The iteration order is unspecified  except that each directory entry is visited only once   If you don t want to recursively iterate over the entries of subdirectories  then directory iterator should be used   Both iterators returns an object of directory entry  directory entry has various useful member functions like is regular file  is directory  is socket  is symlink etc  The path   member function returns an object of std  filesystem  path and it can be used to get file extension  filename  root name   Consider the example below  I have been using Ubuntu and compiled it over the terminal using   g   example cpp --std c  17 -lstdc  fs -Wall    include  lt iostream gt   include  lt string gt   include  lt filesystem gt   void listFiles std  string path        for  auto amp  dirEntry  std  filesystem  recursive directory iterator path             if   dirEntry is regular file                  std  cout  lt  lt   Directory     lt  lt  dirEntry path    lt  lt  std  endl              continue                    std  filesystem  path file   dirEntry path            std  cout  lt  lt   Filename     lt  lt  file filename    lt  lt    extension     lt  lt  file extension    lt  lt  std  endl            int main         listFiles            return 0

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If using the Win32 API you can use the FindFirstFile and FindNextFile functions   http   msdn microsoft com en-us library aa365200 VS 85  aspx  For recursive traversal of directories you must inspect each WIN32 FIND DATA dwFileAttributes to check if the FILE ATTRIBUTE DIRECTORY bit is set  If the bit is set then you can recursively call the function with that directory  Alternatively you can use a stack for providing the same effect of a recursive call but avoiding stack overflow for very long path trees    include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     int main int argc  char  argv          vector lt wstring gt  files       if  ListFiles L F   cvsrepos   L     files             for  vector lt wstring gt   iterator it   files begin                  it    files end                    it                wcout  lt  lt  it- gt c str    lt  lt  endl                      return 0

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If using the Win32 API you can use the FindFirstFile and FindNextFile functions   http   msdn microsoft com en-us library aa365200 VS 85  aspx  For recursive traversal of directories you must inspect each WIN32 FIND DATA dwFileAttributes to check if the FILE ATTRIBUTE DIRECTORY bit is set  If the bit is set then you can recursively call the function with that directory  Alternatively you can use a stack for providing the same effect of a recursive call but avoiding stack overflow for very long path trees    include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     int main int argc  char  argv          vector lt wstring gt  files       if  ListFiles L F   cvsrepos   L     files             for  vector lt wstring gt   iterator it   files begin                  it    files end                    it                wcout  lt  lt  it- gt c str    lt  lt  endl                      return 0

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You can use ftw 3  or nftw 3  to walk a filesystem hierarchy in C or C   on POSIX systems

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A fast solution is using C s Dirent h library   Working code fragment from Wikipedia    include  lt stdio h gt   include  lt dirent h gt   int listdir const char  path        struct dirent  entry      DIR  dp       dp   opendir path       if  dp    NULL            perror  opendir  Path does not exist or could not be read             return -1             while   entry   readdir dp            puts entry- gt d name        closedir dp       return 0

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From C  17 onward  the  lt filesystem gt  header  and range-for  you can simply do this    include  lt filesystem gt   using recursive directory iterator   std  filesystem  recursive directory iterator      for  const auto amp  dirEntry   recursive directory iterator myPath        std  cout  lt  lt  dirEntry  lt  lt  std  endl    As of C  17  std  filesystem is part of the standard library and can be found in the  lt filesystem gt  header  no longer  experimental

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You don t  Standard C   doesn t expose to concept of a directory  Specifically it doesn t give any way to list all the files in a directory   A horrible hack would be to use system   calls and to parse the results  The most reasonable solution would be to use some kind of cross-platform library such as Qt or even POSIX

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Boost  filesystem provides recursive directory iterator  which is quite convenient for this task    include  boost filesystem hpp   include  lt iostream gt   using namespace boost  filesystem   recursive directory iterator end  for  recursive directory iterator it        it    end    it        std  cout  lt  lt   it  lt  lt  std  endl

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You don t  Standard C   doesn t expose to concept of a directory  Specifically it doesn t give any way to list all the files in a directory   A horrible hack would be to use system   calls and to parse the results  The most reasonable solution would be to use some kind of cross-platform library such as Qt or even POSIX

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You need to call OS-specific functions for filesystem traversal  like open   and readdir    The C standard does not specify any filesystem-related functions

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On C  17 you can by this way    include  lt filesystem gt   include  lt iostream gt   include  lt vector gt  namespace fs   std  filesystem   int main         std  ios base  sync with stdio false       for  const auto  amp entry   fs  recursive directory iterator  quot   quot              if  entry path   extension       quot  png quot                 std  cout  lt  lt  entry path   string    lt  lt  std  endl                                   return 0

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In standard C    technically there is no way to do this since standard C   has no conception of directories  If you want to expand your net a little bit  you might like to look at using Boost FileSystem  This has been accepted for inclusion in TR2  so this gives you the best chance of keeping your implementation as close as possible to the standard   An example  taken straight from the website   bool find file  const path  amp  dir path             in this directory                  const std  string  amp  file name     search for this name                  path  amp  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- gt status                  if   find file  itr- gt path    file name  path found     return true            else if   itr- gt leaf      file name      see below             path found   itr- gt path          return true              return false

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You don t  The C   standard has no concept of directories  It is up to the implementation to turn a string into a file handle  The contents of that string and what it maps to is OS dependent  Keep in mind that C   can be used to write that OS  so it gets used at a level where asking how to iterate through a directory is not yet defined  because you are writing the directory management code    Look at your OS API documentation for how to do this  If you need to be portable  you will have to have a bunch of  ifdefs for various OSes

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Answers of getting all file names recursively with C  11 for Windows and Linux with experimental filesystem   For Windows   include  lt io h gt   include  lt sys types h gt   include  lt sys stat h gt   include  lt windows h gt  void getFiles w string path  vector lt string gt  amp  files        intptr t hFile   0       struct  finddata t fileinfo        string p       if   hFile    findfirst p assign path  append  quot     quot   c str     amp fileinfo      -1            do               if   fileinfo attrib  amp   A SUBDIR                     if  strcmp fileinfo name   quot   quot      0  amp  amp  strcmp fileinfo name   quot    quot      0                      getFiles p assign path  append  quot   quot   append fileinfo name   files                             else                   files push back p assign path  append  quot   quot   append fileinfo name                            while   findnext hFile   amp fileinfo     0            For Linux   include  lt experimental filesystem gt  bool getFiles std  experimental  filesystem  path path  vector lt string gt  amp  filenames        namespace stdfs   std  experimental  filesystem         http   en cppreference com w cpp experimental fs directory iterator     const stdfs  directory iterator end              for  stdfs  directory iterator iter path   iter    end     iter               http   en cppreference com w cpp experimental fs is regular file          if   stdfs  is regular file  iter        comment out if all names  names of directories tc   are required              if  getFiles iter- gt path    filenames                    return true                    else               filenames push back iter- gt path   string                  cout  lt  lt  iter- gt path   string    lt  lt  endl                        return false     Just remember to link -lstdc  fs when you compile it with g   in Linux

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If using the Win32 API you can use the FindFirstFile and FindNextFile functions   http   msdn microsoft com en-us library aa365200 VS 85  aspx  For recursive traversal of directories you must inspect each WIN32 FIND DATA dwFileAttributes to check if the FILE ATTRIBUTE DIRECTORY bit is set  If the bit is set then you can recursively call the function with that directory  Alternatively you can use a stack for providing the same effect of a recursive call but avoiding stack overflow for very long path trees    include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     int main int argc  char  argv          vector lt wstring gt  files       if  ListFiles L F   cvsrepos   L     files             for  vector lt wstring gt   iterator it   files begin                  it    files end                    it                wcout  lt  lt  it- gt c str    lt  lt  endl                      return 0

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You don t  Standard C   doesn t expose to concept of a directory  Specifically it doesn t give any way to list all the files in a directory   A horrible hack would be to use system   calls and to parse the results  The most reasonable solution would be to use some kind of cross-platform library such as Qt or even POSIX

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Answers of getting all file names recursively with C  11 for Windows and Linux with experimental filesystem   For Windows   include  lt io h gt   include  lt sys types h gt   include  lt sys stat h gt   include  lt windows h gt  void getFiles w string path  vector lt string gt  amp  files        intptr t hFile   0       struct  finddata t fileinfo        string p       if   hFile    findfirst p assign path  append  quot     quot   c str     amp fileinfo      -1            do               if   fileinfo attrib  amp   A SUBDIR                     if  strcmp fileinfo name   quot   quot      0  amp  amp  strcmp fileinfo name   quot    quot      0                      getFiles p assign path  append  quot   quot   append fileinfo name   files                             else                   files push back p assign path  append  quot   quot   append fileinfo name                            while   findnext hFile   amp fileinfo     0            For Linux   include  lt experimental filesystem gt  bool getFiles std  experimental  filesystem  path path  vector lt string gt  amp  filenames        namespace stdfs   std  experimental  filesystem         http   en cppreference com w cpp experimental fs directory iterator     const stdfs  directory iterator end              for  stdfs  directory iterator iter path   iter    end     iter               http   en cppreference com w cpp experimental fs is regular file          if   stdfs  is regular file  iter        comment out if all names  names of directories tc   are required              if  getFiles iter- gt path    filenames                    return true                    else               filenames push back iter- gt path   string                  cout  lt  lt  iter- gt path   string    lt  lt  endl                        return false     Just remember to link -lstdc  fs when you compile it with g   in Linux

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You need to call OS-specific functions for filesystem traversal  like open   and readdir    The C standard does not specify any filesystem-related functions

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You don t  The C   standard has no concept of directories  It is up to the implementation to turn a string into a file handle  The contents of that string and what it maps to is OS dependent  Keep in mind that C   can be used to write that OS  so it gets used at a level where asking how to iterate through a directory is not yet defined  because you are writing the directory management code    Look at your OS API documentation for how to do this  If you need to be portable  you will have to have a bunch of  ifdefs for various OSes

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You would probably be best with either boost or c  14 s experimental filesystem stuff  IF you are parsing an internal directory  ie  used for your program to store data after the program was closed   then make an index file that has an index of the file contents  By the way  you probably would need to use boost in the future  so if you don t have it installed  install it  Second of all  you could use a conditional compilation  e g     ifdef WINDOWS   define WINDOWS in your code to compile for windows  endif   The code for each case is taken from https   stackoverflow com a 67336 7077165   ifdef POSIX   unix  linux  etc   include  lt stdio h gt   include  lt dirent h gt   int listdir const char  path        struct dirent  entry      DIR  dp       dp   opendir path       if  dp    NULL            perror  opendir  Path does not exist or could not be read             return -1             while   entry   readdir dp            puts entry- gt d name        closedir dp       return 0     endif  ifdef WINDOWS  include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     endif   so on and so forth

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If using the Win32 API you can use the FindFirstFile and FindNextFile functions   http   msdn microsoft com en-us library aa365200 VS 85  aspx  For recursive traversal of directories you must inspect each WIN32 FIND DATA dwFileAttributes to check if the FILE ATTRIBUTE DIRECTORY bit is set  If the bit is set then you can recursively call the function with that directory  Alternatively you can use a stack for providing the same effect of a recursive call but avoiding stack overflow for very long path trees    include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     int main int argc  char  argv          vector lt wstring gt  files       if  ListFiles L F   cvsrepos   L     files             for  vector lt wstring gt   iterator it   files begin                  it    files end                    it                wcout  lt  lt  it- gt c str    lt  lt  endl                      return 0

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You would probably be best with either boost or c  14 s experimental filesystem stuff  IF you are parsing an internal directory  ie  used for your program to store data after the program was closed   then make an index file that has an index of the file contents  By the way  you probably would need to use boost in the future  so if you don t have it installed  install it  Second of all  you could use a conditional compilation  e g     ifdef WINDOWS   define WINDOWS in your code to compile for windows  endif   The code for each case is taken from https   stackoverflow com a 67336 7077165   ifdef POSIX   unix  linux  etc   include  lt stdio h gt   include  lt dirent h gt   int listdir const char  path        struct dirent  entry      DIR  dp       dp   opendir path       if  dp    NULL            perror  opendir  Path does not exist or could not be read             return -1             while   entry   readdir dp            puts entry- gt d name        closedir dp       return 0     endif  ifdef WINDOWS  include  lt windows h gt   include  lt string gt   include  lt vector gt   include  lt stack gt   include  lt iostream gt   using namespace std   bool ListFiles wstring path  wstring mask  vector lt wstring gt  amp  files        HANDLE hFind   INVALID HANDLE VALUE      WIN32 FIND DATA ffd      wstring spec      stack lt wstring gt  directories       directories push path       files clear         while   directories empty              path   directories top            spec   path   L       mask          directories pop             hFind   FindFirstFile spec c str     amp ffd           if  hFind    INVALID HANDLE VALUE                 return false                      do               if  wcscmp ffd cFileName  L        0  amp  amp                   wcscmp ffd cFileName  L         0                    if  ffd dwFileAttributes  amp  FILE ATTRIBUTE DIRECTORY                        directories push path   L       ffd cFileName                                     else                       files push back path   L       ffd cFileName                                             while  FindNextFile hFind   amp ffd     0            if  GetLastError      ERROR NO MORE FILES                FindClose hFind               return false                     FindClose hFind           hFind   INVALID HANDLE VALUE             return true     endif   so on and so forth

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You don t  The C   standard has no concept of directories  It is up to the implementation to turn a string into a file handle  The contents of that string and what it maps to is OS dependent  Keep in mind that C   can be used to write that OS  so it gets used at a level where asking how to iterate through a directory is not yet defined  because you are writing the directory management code    Look at your OS API documentation for how to do this  If you need to be portable  you will have to have a bunch of  ifdefs for various OSes

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In standard C    technically there is no way to do this since standard C   has no conception of directories  If you want to expand your net a little bit  you might like to look at using Boost FileSystem  This has been accepted for inclusion in TR2  so this gives you the best chance of keeping your implementation as close as possible to the standard   An example  taken straight from the website   bool find file  const path  amp  dir path             in this directory                  const std  string  amp  file name     search for this name                  path  amp  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- gt status                  if   find file  itr- gt path    file name  path found     return true            else if   itr- gt leaf      file name      see below             path found   itr- gt path          return true              return false

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You can use ftw 3  or nftw 3  to walk a filesystem hierarchy in C or C   on POSIX systems

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You can use std  filesystem  recursive directory iterator  But beware  this includes symbolic  soft  links  If you want to avoid them you can use is symlink  Example usage  size t directory size const std  filesystem  path amp  directory        size t size  0        for  const auto amp  entry   std  filesystem  recursive directory iterator directory                 if  entry is regular file    amp  amp   entry is symlink                          size    entry file size                        return size

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You can make it even simpler with the new C  11 range based for and Boost    include  lt boost filesystem hpp gt   using namespace boost  filesystem      struct recursive directory range       typedef recursive directory iterator iterator      recursive directory range path p    p  p          iterator begin     return recursive directory iterator p          iterator end     return recursive directory iterator           path p       for  auto it   recursive directory range dir path         std  cout  lt  lt  it  lt  lt  std  endl

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From C  17 onward  the  lt filesystem gt  header  and range-for  you can simply do this    include  lt filesystem gt   using recursive directory iterator   std  filesystem  recursive directory iterator      for  const auto amp  dirEntry   recursive directory iterator myPath        std  cout  lt  lt  dirEntry  lt  lt  std  endl    As of C  17  std  filesystem is part of the standard library and can be found in the  lt filesystem gt  header  no longer  experimental

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You don t  Standard C   doesn t expose to concept of a directory  Specifically it doesn t give any way to list all the files in a directory   A horrible hack would be to use system   calls and to parse the results  The most reasonable solution would be to use some kind of cross-platform library such as Qt or even POSIX

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On C  17 you can by this way    include  lt filesystem gt   include  lt iostream gt   include  lt vector gt  namespace fs   std  filesystem   int main         std  ios base  sync with stdio false       for  const auto  amp entry   fs  recursive directory iterator  quot   quot              if  entry path   extension       quot  png quot                 std  cout  lt  lt  entry path   string    lt  lt  std  endl                                   return 0

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You can make it even simpler with the new C  11 range based for and Boost    include  lt boost filesystem hpp gt   using namespace boost  filesystem      struct recursive directory range       typedef recursive directory iterator iterator      recursive directory range path p    p  p          iterator begin     return recursive directory iterator p          iterator end     return recursive directory iterator           path p       for  auto it   recursive directory range dir path         std  cout  lt  lt  it  lt  lt  std  endl

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Boost  filesystem provides recursive directory iterator  which is quite convenient for this task    include  boost filesystem hpp   include  lt iostream gt   using namespace boost  filesystem   recursive directory iterator end  for  recursive directory iterator it        it    end    it        std  cout  lt  lt   it  lt  lt  std  endl

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In addition to the above mentioned boost  filesystem you may want to examine wxWidgets  wxDir and Qt  QDir   Both wxWidgets and Qt are open source  cross platform C   frameworks   wxDir provides a flexible way to traverse files recursively using Traverse   or a simpler GetAllFiles   function  As well you can implement the traversal with GetFirst   and GetNext   functions  I assume that Traverse   and GetAllFiles   are wrappers that eventually use GetFirst   and GetNext   functions    QDir provides access to directory structures and their contents  There are several ways to traverse directories with QDir  You can iterate over the directory contents  including sub-directories  with QDirIterator that was instantiated with QDirIterator  Subdirectories flag  Another way is to use QDir s GetEntryList   function and implement a recursive traversal   Here is sample code  taken from here   Example 8-5  that shows how to iterate over all sub directories    include  lt qapplication h gt   include  lt qdir h gt   include  lt iostream gt   int main  int argc  char   argv         QApplication a  argc  argv        QDir currentDir   QDir  current         currentDir setFilter  QDir  Dirs        QStringList entries   currentDir entryList        for  QStringList  ConstIterator entry entries begin    entry  entries end      entry                  std  cout  lt  lt   entry  lt  lt  std  endl            return 0

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You can use std  filesystem  recursive directory iterator  But beware  this includes symbolic  soft  links  If you want to avoid them you can use is symlink  Example usage  size t directory size const std  filesystem  path amp  directory        size t size  0        for  const auto amp  entry   std  filesystem  recursive directory iterator directory                 if  entry is regular file    amp  amp   entry is symlink                          size    entry file size                        return size

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If you are on Windows  you can use the FindFirstFile together with FindNextFile API  You can use FindFileData dwFileAttributes to check if a given path is a file or a directory  If it s a directory  you can recursively repeat the algorithm   Here  I have put together some code that lists all the files on a Windows machine   http   dreams-soft com projects traverse-directory

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You need to call OS-specific functions for filesystem traversal  like open   and readdir    The C standard does not specify any filesystem-related functions

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File tree walk ftw is a recursive way to wall the whole directory tree in the path  More details are here  NOTE   You can also use fts that can skip hidden files like   or    or  bashrc  include  lt ftw h gt   include  lt stdio h gt   include  lt sys stat h gt   include  lt string h gt     int list const char  name  const struct stat  status  int type         if  type    FTW NS                  return 0               if  type    FTW F                  printf  quot 0 3o t s n quot   status- gt st mode amp 0777  name                if  type    FTW D  amp  amp  strcmp  quot   quot   name     0                  printf  quot 0 3o t s  n quot   status- gt st mode amp 0777  name               return 0     int main int argc  char  argv           if argc    1                  ftw  quot   quot   list  1               else                 ftw argv 1   list  1                return 0     output looks like following  0755      Shivaji  0644      Shivaji 20200516 204454 png 0644      Shivaji 20200527 160408 png 0644      Shivaji 20200527 160352 png 0644      Shivaji 20200520 174754 png 0644      Shivaji 20200520 180103 png 0755      Saif  0644      Saif Snapchat-1751229005 jpg 0644      Saif Snapchat-1356123194 jpg 0644      Saif Snapchat-613911286 jpg 0644      Saif Snapchat-107742096 jpg 0755      Milind  0644      Milind IMG 1828 JPG 0644      Milind IMG 1839 JPG 0644      Milind IMG 1825 JPG 0644      Milind IMG 1831 JPG 0644      Milind IMG 1840 JPG  Let us say if you want to match a filename  example  searching for all the   jpg    jpeg    png files   for a specific needs  use fnmatch    include  lt ftw h gt    include  lt stdio h gt    include  lt sys stat h gt    include  lt iostream gt    include  lt fnmatch h gt    static const char  filters             quot   jpg quot    quot   jpeg quot    quot   png quot        int list const char  name  const struct stat  status  int type          if  type    FTW NS                  return 0               if  type    FTW F                  int i           for  i   0  i  lt  sizeof filters    sizeof filters 0    i                      if the filename matches the filter                  if  fnmatch filters i   name  FNM CASEFOLD     0                     printf  quot 0 3o t s n quot   status- gt st mode amp 0777  name                    break                                         if  type    FTW D  amp  amp  strcmp  quot   quot   name     0                    printf  quot 0 3o t s  n quot   status- gt st mode amp 0777  name               return 0       int main int argc  char  argv            if argc    1                  ftw  quot   quot   list  1               else                 ftw argv 1   list  1                return 0

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A fast solution is using C s Dirent h library   Working code fragment from Wikipedia    include  lt stdio h gt   include  lt dirent h gt   int listdir const char  path        struct dirent  entry      DIR  dp       dp   opendir path       if  dp    NULL            perror  opendir  Path does not exist or could not be read             return -1             while   entry   readdir dp            puts entry- gt d name        closedir dp       return 0

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In standard C    technically there is no way to do this since standard C   has no conception of directories  If you want to expand your net a little bit  you might like to look at using Boost FileSystem  This has been accepted for inclusion in TR2  so this gives you the best chance of keeping your implementation as close as possible to the standard   An example  taken straight from the website   bool find file  const path  amp  dir path             in this directory                  const std  string  amp  file name     search for this name                  path  amp  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- gt status                  if   find file  itr- gt path    file name  path found     return true            else if   itr- gt leaf      file name      see below             path found   itr- gt path          return true              return false

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In standard C    technically there is no way to do this since standard C   has no conception of directories  If you want to expand your net a little bit  you might like to look at using Boost FileSystem  This has been accepted for inclusion in TR2  so this gives you the best chance of keeping your implementation as close as possible to the standard   An example  taken straight from the website   bool find file  const path  amp  dir path             in this directory                  const std  string  amp  file name     search for this name                  path  amp  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- gt status                  if   find file  itr- gt path    file name  path found     return true            else if   itr- gt leaf      file name      see below             path found   itr- gt path          return true              return false

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You don t  The C   standard has no concept of directories  It is up to the implementation to turn a string into a file handle  The contents of that string and what it maps to is OS dependent  Keep in mind that C   can be used to write that OS  so it gets used at a level where asking how to iterate through a directory is not yet defined  because you are writing the directory management code    Look at your OS API documentation for how to do this  If you need to be portable  you will have to have a bunch of  ifdefs for various OSes

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We are in 2019  We have filesystem standard library in C    The Filesystem library provides facilities for performing operations on file systems and their components  such as paths  regular files  and directories   There is an important note on this link if you are considering portability issues  It says      The filesystem library facilities may be unavailable if a hierarchical file system is not accessible to the implementation  or if it does not provide the necessary capabilities  Some features may not be available if they are not supported by the underlying file system  e g  the FAT filesystem lacks symbolic links and forbids multiple hardlinks   In those cases  errors must be reported    The filesystem library was originally developed as boost filesystem  was published as the technical specification ISO IEC TS 18822 2015  and finally merged to ISO C   as of C  17  The boost implementation is currently available on more compilers and platforms than the C  17 library    adi-shavit has answered this question when it was part of std  experimental and he has updated this answer in 2017  I want to give more details about the library and show more detailed example   std  filesystem  recursive directory iterator is an LegacyInputIterator that iterates over the directory entry elements of a directory  and  recursively  over the entries of all subdirectories  The iteration order is unspecified  except that each directory entry is visited only once   If you don t want to recursively iterate over the entries of subdirectories  then directory iterator should be used   Both iterators returns an object of directory entry  directory entry has various useful member functions like is regular file  is directory  is socket  is symlink etc  The path   member function returns an object of std  filesystem  path and it can be used to get file extension  filename  root name   Consider the example below  I have been using Ubuntu and compiled it over the terminal using   g   example cpp --std c  17 -lstdc  fs -Wall    include  lt iostream gt   include  lt string gt   include  lt filesystem gt   void listFiles std  string path        for  auto amp  dirEntry  std  filesystem  recursive directory iterator path             if   dirEntry is regular file                  std  cout  lt  lt   Directory     lt  lt  dirEntry path    lt  lt  std  endl              continue                    std  filesystem  path file   dirEntry path            std  cout  lt  lt   Filename     lt  lt  file filename    lt  lt    extension     lt  lt  file extension    lt  lt  std  endl            int main         listFiles            return 0

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In addition to the above mentioned boost  filesystem you may want to examine wxWidgets  wxDir and Qt  QDir   Both wxWidgets and Qt are open source  cross platform C   frameworks   wxDir provides a flexible way to traverse files recursively using Traverse   or a simpler GetAllFiles   function  As well you can implement the traversal with GetFirst   and GetNext   functions  I assume that Traverse   and GetAllFiles   are wrappers that eventually use GetFirst   and GetNext   functions    QDir provides access to directory structures and their contents  There are several ways to traverse directories with QDir  You can iterate over the directory contents  including sub-directories  with QDirIterator that was instantiated with QDirIterator  Subdirectories flag  Another way is to use QDir s GetEntryList   function and implement a recursive traversal   Here is sample code  taken from here   Example 8-5  that shows how to iterate over all sub directories    include  lt qapplication h gt   include  lt qdir h gt   include  lt iostream gt   int main  int argc  char   argv         QApplication a  argc  argv        QDir currentDir   QDir  current         currentDir setFilter  QDir  Dirs        QStringList entries   currentDir entryList        for  QStringList  ConstIterator entry entries begin    entry  entries end      entry                  std  cout  lt  lt   entry  lt  lt  std  endl            return 0

[c++] How do you iterate through every file/directory recursively in standard C++?

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