List all text files in directory in C++ - c++

Question

I am trying to store the name of all txt files in a directory in a string and print them out. I need to count the number of txt files in the directory and then print the names. The part of counting is working, but I can't seem to get the name working. I have found some examples but they don't work in visual studio which is what I'm using.
Here is my code.
int main() {
bool x = true;
int i = 0;
wchar_t* file = L"../Menu/Circuitos/*.txt";
WIN32_FIND_DATA FindFileData;
HANDLE hFind;
hFind = FindFirstFile(file, &FindFileData);
if (hFind != INVALID_HANDLE_VALUE) {
i++;
while ((x = FindNextFile(hFind, &FindFileData)) == TRUE) {
i++;
}
}
cout << "number of files " << i << endl;
return 0;
}

Answer 1

FindFirstFile already has the first valid handle. If you immediately call FindNextFile then the first handle is lost. The file count in your example would be wrong.
Use do-while loop istead.
Also, the handle obtained from FindFirstFile must be closed with FindClose
HANDLE hFind;
hFind = FindFirstFile(file, &FindFileData);
if (hFind != INVALID_HANDLE_VALUE)
{
do {
wcout << FindFileData.cFileName << "\n";
i++;
} while (FindNextFile(hFind, &FindFileData));
FindClose(hFind);
}
cout << "number of files " << i << endl;
Use std::vector and std::wstring to store the items
#include <string>
#include <vector>
...
std::vector<std::wstring> vs;
HANDLE hFind;
hFind = FindFirstFile(file, &FindFileData);
if (hFind != INVALID_HANDLE_VALUE)
{
do {
vs.push_back(FindFileData.cFileName);
} while (FindNextFile(hFind, &FindFileData));
FindClose(hFind);
}
std::cout << "count:" << vs.size() << "\n";
for (auto item : vs)
std::wcout << item << "\n";
For some older compilers auto may not be available, use this instead
for (int i = 0; i < vs.size(); i++)
std::wcout << vs[i] << "\n";
Note, Windows API works with c-strings. In many cases you have to use .c_str() to obtain character array. For example:
if (vs.size())
{
std::wstring str = vs[0];
MessageBox(0, str.c_str(), 0, 0);
}

Answer 2

Here is a portable version using the new ISO Standard Filesystem Library TS (technical specification) for those with compilers that support it:
#include <vector>
#include <iostream>
#include <algorithm>
#include <experimental/filesystem>
// for readability
namespace fs = std::experimental::filesystem;
/**
* Function object to test directory entries
* for a specific file extension.
*/
struct file_extension_is
{
std::string ext;
file_extension_is(std::string const& ext): ext(ext) {}
bool operator()(fs::directory_entry const& entry) const
{
return entry.path().extension() == ext;
}
};
int main(int, char* argv[])
{
try
{
// directory supplied on the command line if present
// else current directory
fs::path dir = argv[1] ? argv[1] : ".";
// place to store the results
std::vector<fs::directory_entry> entries;
// copy directory entries that have file extension ".txt"
// to the results
fs::directory_iterator di(dir);
fs::directory_iterator end;
std::copy_if(di, end, std::back_inserter(entries),
file_extension_is(".txt"));
// print it all out
std::cout << "Number of files: " << entries.size() << '\n';
for(auto const& entry: entries)
std::cout << entry.path().string() << '\n';
}
catch(std::exception const& e)
{
std::cerr << e.what() << '\n';
}
catch(...)
{
std::cerr << "Unknown exception." << '\n';
}
}