Как проверить, есть файл в папке или нет?

FILE * pFile;
 
if(pFile != NULL)
    pFile = fopen("C:\\Users\\admin\\Documents\\Visual Studio 2010\\Projects\\Store1\\Store1\\test.txt", "r+");
else 
        pFile = fopen("C:\\Users\\admin\\Documents\\Visual Studio 2010\\Projects\\Store1\\Store1\\test.txt", "w");

 
   fstream f("C:\\Users\\admin\\Documents\\Visual Studio 2010\\Projects\\Store1\\Store1\\test.txt", ios::in);
   if (!f.is_open())
       f.open("C:\\Users\\admin\\Documents\\Visual Studio 2010\\Projects\\Store1\\Store1\\test.txt", ios::out);

// Valid file path name (file is there).
    char buffer_1[ ] = "C:\\TEST\\file.txt"; 
    char *lpStr1;
    lpStr1 = buffer_1;
    
    // Invalid file path name (file is not there).
    char buffer_2[ ] = "C:\\TEST\\file.doc"; 
    char *lpStr2;
    lpStr2 = buffer_2;
    
    // Return value from "PathFileExists".
    int retval;
    
    // Search for the presence of a file with a true result.
    retval = PathFileExists(lpStr1);
    if(retval == 1)
    {
        cout << "Search for the file path of : " << lpStr1 << endl;
        cout << "The file requested \"" << lpStr1 << "\" is a valid file" << endl;
        cout << "The return from function is : " << retval << endl;
    }
    
    else
    {
        cout << "\nThe file requested " << lpStr1 << " is not a valid file" << endl;
        cout << "The return from function is : " << retval << endl;
    }
    
    // Search for the presence of a file with a false result.
    retval = PathFileExists(lpStr2);
    
    if(retval == 1)
    {
        cout << "\nThe file requested " << lpStr2 << "is a valid file" << endl;
        cout << "Search for the file path of : " << lpStr2 << endl;
        cout << "The return from function is : " << retval << endl;
    }
    else
    {
        cout << "\nThe file requested \"" << lpStr2 << "\" is not a valid file" << endl;
        cout << "The return from function is : " << retval << endl;
    }

retval = PathFileExists((LPCTSTR)lpStr1);

pc_str1 = reinterpret_cast<LPCTSTR>(c_buf1);

FILE *f = fopen(имя файла, "a");