Can't input value to the variable. Ifstream in win32 gui

[z214]

I am a student on a final project. I'm writing an apps that read from csv in win32 app. But I'm not using CStdioFile. I'm using ifstream. This is my code for reading

time_t long_time;
time(&long_time);
tm* st = localtime(&long_time);

string line;
char get;
int i;

fstream opn;
opn.open(path);
for(i = 1; i <= jumlahdata; i++)
{

getline(opn, line,'\n');
std::istringstream iss(line);

iss >> st->tm_mon >> get >> st->tm_mday >> get >> st->tm_year >>
st->tm_hour >> get >> st->tm_min >> get >> tinggi[i];
st->tm_sec=0;
st->tm_mon--;
st->tm_year-=1900;
waktu[i] = mktime(st);
}
opn.close()

This script work well in console app. But when I used it on the win32 app this script went error.

void CMainFrame::OnFileOpen40001()
{
// TODO: Add your command handler code here
CString str;
//CRect rc;
//string path;

//CFile ifp;
//fstream opn;
CFileDialog FileDlg(true, _T("*.csv"), NULL,NULL, _T("Comma Separated Value|*.csv"));
if (FileDlg.DoModal()==IDOK)
{
str=FileDlg.GetFolderPath();
str+='\\'+FileDlg.GetFileName();
//string path((LPCTSTR)str);
// Convert a TCHAR string to a LPCSTR
CT2CA pszConvertedAnsiString (str);
// construct a std::string using the LPCSTR input
//std::string path (pszConvertedAnsiString);
string path (pszConvertedAnsiString);
//opn.open(str);
//ifp=fopen((str),"r");
/*
CFileException e;
if(ifp.Open(str,CFile::modeRead))
e.ReportError();
*/
n = data::countdata(path);
CString a;
waktu = new int unsigned [n+1];
tinggi = new double [n+1];
data::readdata(path, waktu, tinggi, n);
CClientDC dc(this);
a.Format(_T(" Data tinggi = %d"),tinggi[1]);
dc.TextOutW(250,250,str);
dc.TextOutW(250,350,a);

}
}

Please help me. I can't figure the problem.

[Silvestar]

Tell us what's the error u get and on what line. Btw try using OPENFILENAME struct...