如何使用C ++列出Windows目录中的所有CSV文件？

Question

I'm a bit new to C++ and I've to list all CSV files in a Windows Directory, I've googled and I found a lot of ways to list all files in a directory and I came up with the following solution:

int listFiles(string addDir, vector<string> &list) {
    DIR *dir = 0;
    struct dirent *entrada = 0;
    int isFile = 32768;

    dir = opendir(addDir.c_str());

    if (dir == 0) {
        cerr << "Could not open the directory." << endl;
        exit(1);
    }

    while (entrada = readdir(dir))
        if (entrada->d_type == isFile)
        {
        list.push_back(entrada->d_name);
        cout << entrada->d_name << endl;
        }
    closedir(dir);

    return 0;
}

It is using the dirent.h for Windows (I'm using VS2013) but the problems are: - Is it correct to set isFile = 32768? Will it always work on Windows? - How to know if the file is a CSV file?

Another thing, I've tried to use windows.h / FindNextFile but it didn't work. Is it better to use FindNextFile or the above solution?

I guess FindNextFile would be easier to list only the CSV File, but I don't know how to do it.

My exit should be a string because it is an input of a function that reads the CSV Files.

Tks guys.

PS: I cant use boost...

Answer 1

int listFiles(const string& addDir, vector<string> &list, const std::string& _ext) {
    DIR *dir = 0;
    struct dirent *entrada = 0;
    int isFile = 32768;
    std::string ext("." + _ext);
    for (string::size_type i = 0; i < ext.length(); ++i)
        ext[i] = tolower(ext[i]);

    dir = opendir(addDir.c_str());

    if (dir == 0) {
        cerr << "Could not open the directory." << endl;
        exit(1);
    }

    while (entrada = readdir(dir))
    if (entrada->d_type == isFile)
    {
        const char *name = entrada->d_name;
        size_t len = strlen(entrada->d_name);
        if (len >= ext.length()) {
            std::string fext(name + len - ext.length());
            for (string::size_type i = 0; i < fext.length(); ++i)
                fext[i] = tolower(fext[i]);

            if (fext == ext) {
                list.push_back(entrada->d_name);
                cout << entrada->d_name << endl;
            }
        }
    }
    closedir(dir);

    return 0;
}
int main()
{

    vector<string> flist;
    listFiles("c:\\", flist, "csv");
    system("PAUSE");
}

If you want to use FindNextFile, msdn has an example for enumerating all fiels in a directory here which you can adapt.

---

EDIT: To expand on the windows API method:

argv is of type TCHAR* , meaning either char* or wchar_t* depending on #ifdef UNICODE . It's a type used by all Windows API calls which take a string parameter. To create a TCHAR literal you can use TEXT("text") . To create a wchar_t literal you can use L"text" . If you do not want to use TCHAR semantics you can redefine main to be of type int main(int argc, char* argv) , or int wmain(int argc, wchar_t* arv) . Converting between the two types involves dealing with unicode and code pages, which you should probably use a 3rd party library for.

Converting from ASCII ( std::string or char* with char points in 0-127) to unicode( std::wstring or wchar_t* is a simple matter of creating a std::wstring(std::string.cbegin(), std::string.cend()) .

Here is a code example demonstrating use of WinAPI functions to list files in a directory:

#include <windows.h>
#incldue <string>
#include <iostream>

#ifdef UNICODE
typedef std::wstring tstring;
#else
typedef std::string tstring;
#endif
#ifdef UNICODE
std::wostream& tcout = std::wcout;
std::wostream& tcerr = std::wcerr;
#else 
std::ostream& tcout = std::cout;
std::ostream& tcerr = std::cerr;
#endif

int listFiles(const tstring& directory, std::vector<tstring> &list, const tstring& extension)
{
    using std::endl;
    WIN32_FIND_DATA file;
    HANDLE hListing;
    int error;

    tstring query;
    if (directory.length() > MAX_PATH - 2 - extension.length())
        tcerr << "directory name too long" << endl;
    query = directory + TEXT("*.") + extension;

    hListing = FindFirstFile(query.c_str(), &file);
    if (hListing == INVALID_HANDLE_VALUE) {
        error = GetLastError();
        if (error == ERROR_FILE_NOT_FOUND)
            tcout << "no ." << extension << " files found in directory " << directory << endl;
        return error;
    }

    do
    {
        if ((file.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) == 0)
        {
            tcout << file.cFileName << endl;
            list.push_back(file.cFileName);
        }
    } while (FindNextFile(hListing, &file) != 0);

    error = GetLastError();
    if (error == ERROR_NO_MORE_FILES)
        error = 0;

    FindClose(hListing);
    return error;
}
int _tmain(int argc, TCHAR* argv[])
{
    std::vector<tstring> files;
    listFiles(TEXT("C:\\"), files, TEXT("sys"));
    if (argc > 1)
        listFiles(argv[1], files, TEXT("csv"));
}

If you want to simplify it, you can make your application either locked in unicode or completely ignorant of unicode by removing all T (TCHAR, TEXT(), the newly-defined tstring, tcout, tcerr) variants and using purely wide or non-wide types (ie. char*, string, simple literals, cout OR wchar_t*, wstring, L"" literals, wcout). If you do this, you need to use the specialied functions of WINAPI functions (ie FindFirstFileA for non-wide and FindFirstFileW for wide)