c++ Windows forms, file reading (total noob)

[Migeria]

Few days ago I started my term paper and I want to do it in windows forms, but so far it's total headache ~_~

for starter, I want to read file on button click
top of Form header file

#pragma once
#include <iostream>
#include <fstream>
//#include <string> 

... lots of **** and then

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
				 using namespace std;
//			string line, tag;
//			size_t pos, pos2;
			fstream duomf("DB/tags.db",ios::in);
			if(duomf.open())
				label2->Text="FILE IS OPEN";
/*			while(getline(duomf, line))
			{
				pos = line.find("|");
				pos2 = line.find("\n");
				tag = line.substr(0, pos);
			} */
			duomf.close();
			 }

in console application that would be correct, but I get

c:\documents and settings\kyoshiro\desktop\folders\3semestras\c++\programavimas cpp\nd\tager\tager\tager\Form2.h(136): error C2661: 'std::basic_fstream<_Elem,_Traits>::open' : no overloaded function takes 0 arguments
          with
          [
              _Elem=char,
              _Traits=std::char_traits<char>
          ]

Build FAILED.

on Visual Studio 2010

well ok... I put in arguments, so it's if(duomf.open("DB/tags.db",ios::in)) on 6th line but now error is

c:\documents and settings\kyoshiro\desktop\folders\3semestras\c++\programavimas cpp\nd\tager\tager\tager\Form2.h(135): error C2451: conditional expression of type 'void' is illegal
          Expressions of type void cannot be converted to other types

Build FAILED.

So whats wrong with my head?
I know I could finish my term paper in few days if I did program as console application, but I don't want to do so.

[3hM2Nwbp]

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
using namespace std;
fstream duomf;
duomf.open("DB/tags.db",ios::in); //<-- Returns void
if(!duomf) //<-- operator!
{/*failed*/}
else
{/*Succeeded*/}

http://cplusplus.com/reference/iostream/ifstream/open/

http://cplusplus.com/reference/iostream/ios/operatornot/

[Migeria]

lol.. I tried that before, but I got dozens of errors :D
now I checked it again and noticed that I included Form2.h in wrong place.
Damn >.< VS with those stupid stdafx files and untrained users head

Anyways, thanks for helping me Luc Lieber o(^-^)o

[3hM2Nwbp]

You can switch off the use of precompiled headers in Visual Studio if you wish. It's in your project properties.