Error in Listing File from Directory in C++ - c++

Question

I am having a problem with my code. Whenever i run the program, the last file search would return a zero value where in it shouldn't.
here is the code:
#include <vector>
#include <string>
#include <windows.h>
#include <stdio.h>
#include <iostream>
#include <conio.h>
using namespace std;
string GetPath(string path){
char directory[1024];
vector <string> filelist;
strcpy_s(directory,path.c_str());
BOOL checker;
WIN32_FIND_DATA findFileData;
HANDLE hFind = FindFirstFile((LPCSTR)directory, &findFileData);
cout <<"Files in:" <<"\n"<<directory<<"\n"<<endl;
checker = FindNextFile(hFind, &findFileData);
while(checker)
{
checker = FindNextFile(hFind, &findFileData);
filelist.push_back(findFileData.cFileName);//save file list in vector
cout << findFileData.cFileName << endl;
}
DWORD error = GetLastError();
if( error != ERROR_NO_MORE_FILES)
{
}
/*for (unsigned i=1;i<filelist.size();i++){
cout << filelist[i]<<endl;//print out the vector
}*/
return 0;
}
int main()
{
string path;
path="C:\\Program Files\\*.*";
vector <string> handler;
path = GetPath(path);
}

Answer 1

Try this as a sanity check:
#include <tchar.h>
#include <stdexcept>
#include <vector>
#include <string>
#include <iostream>
#include <windows.h>
#ifdef UNICODE
typedef std::wstring tstring;
static std::wostream& tcout = std::wcout;
#else
typedef std::string tstring;
static std::ostream& tcout = std::cout;
#endif
std::vector<tstring> GetPath(tstring const& path)
{
WIN32_FIND_DATA findFileData;
HANDLE const hFind = FindFirstFile(path.c_str(), &findFileData);
if (hFind == INVALID_HANDLE_VALUE)
throw std::runtime_error(""); // realistically, throw something useful
std::vector<tstring> filelist;
do filelist.push_back(findFileData.cFileName);
while (FindNextFile(hFind, &findFileData));
FindClose(hFind);
if (GetLastError() != ERROR_NO_MORE_FILES)
throw std::runtime_error(""); // realistically, throw something useful
return filelist;
}
int _tmain()
{
std::vector<tstring> files = GetPath(_T("C:\\Program Files\\*.*"));
for (std::vector<tstring>::const_iterator iter = files.begin(), iter_end = files.end(); iter != iter_end; ++iter)
tcout << *iter << _T('\n');
}
If it works, clean up the error handling logic and use it ;-]. If it doesn't, then #young was correct and you you have localization issues; change your project settings to use Unicode as the character set and it should work.

Answer 2

First, you need to check hFind returned from FindFirstFile() as it may return INVALID_HANDLE_VALUE.
Second, your while loop should look like this
while(FindNextFile(hFind, &findFileData)!= 0)
{
filelist.push_back(findFileData.cFileName);//save file list in vector
}
DWORD error = GetLastError();
if( error != ERROR_NO_MORE_FILES)
{
// You are not expecting this error so you might want to do something here.
}

Answer 3

It seems to me that you shouldn't be calling FindNextFile inside the loop: I imagine that if you look at you output carefully you will notice that every SECOND file is missing from your list.
This is because the call to FindNextFile in the while condition loads the next file detail into FindFileData. Then the next line of code (inside the while loop) does this process again overwriting the first match with the second. Thus you only get every second entry.
For even numbers of files you also get the difficulty you describe at the end.

Answer 4

Well one thing I notice is that your GetPath function returns a string. At the end you do: return 0; This will call the string constructor that takes a char* as parameter and will attempt to construct the string with a null pointer. I assume this will lead to a crash in most STl implementations :-).
Coming to your problem, you could try this:
#include <Strsafe.h>
//from MSDN
void
DisplayError(LPTSTR lpszFunction)
{
// Retrieve the system error message for the last-error code
LPVOID lpMsgBuf;
LPVOID lpDisplayBuf;
DWORD dw = GetLastError();
FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
dw,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR) &lpMsgBuf,
0,
NULL );
// Display the error message and exit the process
lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT,
(lstrlen((LPCTSTR)lpMsgBuf) + lstrlen((LPCTSTR)lpszFunction) + 40) * sizeof(TCHAR));
StringCchPrintf((LPTSTR)lpDisplayBuf,
LocalSize(lpDisplayBuf) / sizeof(TCHAR),
TEXT("%s failed with error %d: %s"),
lpszFunction, dw, lpMsgBuf);
MessageBox(NULL, (LPCTSTR)lpDisplayBuf, TEXT("Error"), MB_OK);
LocalFree(lpMsgBuf);
LocalFree(lpDisplayBuf);
}
void
GetPath(string path)
{
vector <string> filelist;
WIN32_FIND_DATA findFileData;
HANDLE hFind = FindFirstFile(path.c_str(), &findFileData);
if (hFind == INVALID_HANDLE_VALUE)
{
DisplayError("FindFirstFile");
return;
}
cout <<"Enumerating files in: " <<"\n"<< path << "\n" << endl;
while( FindNextFile(hFind, &findFileData) != 0 )
{
filelist.push_back( findFileData.cFileName );//save file list in vector
}
if ( ERROR_NO_MORE_FILES != GetLastError() )
{
DisplayError("FindFirstFile");
}
FindClose(hFind);
unsigned int listSize = filelist.size();
cout << "List Count: " << listSize << "\n";
for (unsigned i=0; i < listSize; ++i)
{
cout << filelist[i] << "\n";//print out the vector
}
cout << "\nListing complete\n" << endl;
}
int main()
{
string path;
path="C:\\Program Files\\*.*";
GetPath(path);
}
And tell us what error code do you receive after the while loop completes.

Answer 5

This is my answer
#include <vector>
#include <string>
#include <windows.h>
#include <stdio.h>
#include <iostream>
#include <conio.h>
#include <sys\types.h>
#include <sys\stat.h>
#include <time.h>
#include <exception>
#include <WinBase.h>
#include <tchar.h>
#include <strsafe.h>
#include <algorithm>
using namespace std;
int ifException(string directory) throw()
{
DWORD returnvalue;
returnvalue = GetFileAttributes(directory.c_str());
if(returnvalue == ((DWORD)-1))
{
return 0;
}
else
{
return 1;
}
}
string FileTime(string filename, string path){
char timeStr[ 100 ] = "";
char fpath[9999];
string buffer;
replace (path.begin(),path.end(),'*','\0');
replace (path.begin(),path.end(),'.','\0');
strcpy_s(fpath,path.c_str());
path = filename;
struct stat buf;
string filepath;
filepath = fpath;
filepath += filename;
//cout << filepath << endl;
strcpy_s(fpath,filepath.c_str());
if (!stat(fpath, &buf))
{
strftime(timeStr, 100, "%d-%m-%Y %H:%M:%S", localtime(&buf.st_mtime));
}
buffer = filename;
buffer += "\t\t";
buffer +=timeStr;
return buffer;
}
vector <string> GetPath(string path)
{
char directory[9999];
vector <string> filelist;
string buffer;
strcpy_s(directory,path.c_str());
BOOL checker;
WIN32_FIND_DATA findFileData;
HANDLE hFind = FindFirstFile((LPCSTR)directory, &findFileData);
try
{
ifException(directory);
}catch(int i)
{
if (i==0)
{
_getch();
exit(1);
}
}
buffer = findFileData.cFileName;
filelist.push_back(buffer);
checker = FindNextFile(hFind, &findFileData);
while(checker)
{
checker = FindNextFile(hFind, &findFileData);
buffer = findFileData.cFileName;
buffer = FileTime(buffer,path);
filelist.push_back(buffer);//save file list in vector
if(checker == 0)
{
filelist.resize(filelist.size());
return filelist;
}
}
return filelist;
}
int main()
{
string path;
path="C:\\Documents and Settings\\OJT\\My Documents\\*.*";// the directory
vector <string> handler;
handler = GetPath(path);
for (unsigned i=1;i<handler.size()-1;i++)
{
cout << handler[i]<<endl;//print out the vector
}
_getch();
}