passing ifstream and ofstream types in functions

[pfjf2]

Hello, I am new to C++ and trying to get to grips with it. Particularly I am having difficulty using both header files and passing ifstream and ofstream types into a function ( i am attempting to kill two birds with one stone). I am getting numerous errors. Any help would be greatly appreciated.

My codes and errors are listed below

Header.h

#pragma once
#ifndef HEADERCODE_h
#define HEADERCODE_H

int factorial(int number);

void write_in_file(ifstream& instream, ofstream& outstream,int& user_integer);

#endif

Header.cpp

#include "stdafx.h"
#include <iostream>
#include <cmath>
#include <fstream>
#include "Header.h"
using namespace std;

int factorial(int number)
{

int product = 1;
for (int i = 1; i <= number; i++) {
product = product*i;
}

return product;
}

void write_in_file(ifstream& instream, ofstream& outstream, int& user_integer) {

outstream << "The sqare root of " << user_integer << " is " << sqrt(user_integer) << " and the factorial is " << factorial(user_integer);

}

main.cpp


#include "stdafx.h"
#include <iostream>
#include <cmath>
#include <fstream>
#include "Header.h"
using namespace std;

int main() {

ifstream in_stream;
ofstream out_stream;
int user_integer;

in_stream.open("file");
out_stream.open("file");

cout << " Enter a positive integer \n";
cin >> user_integer;
write_in_file(in_stream, out_stream,user_integer);

in_stream.close();
out_stream.close();
return 0;
}


errors:


Error C2065 'ifstream': undeclared identifier
Error C2065 'instream': undeclared identifier
Error C2065 'ofstream': undeclared identifier
Error C2065 'outstream': undeclared identifier
Error C2062 type 'int' unexpected
Error identifier "ifstream" is undefined
Error identifier "instream" is undefined
Error (active) expression preceding parentheses of apparent call must have (pointer-to-) function type ( this is when I call the function write_in_file)

[leourb]

I guess you have made a bit of confusion with what you wrote. Code is a bit messy. I am not an experienced programmer but, according Stroustrup's way, he says it is better if you keep ifs/ofs separated.

You can set up two functions that compile a vector to import and another one to export or simply prints results out.

[MiiNiPaa]

Where are those errors are? Where they are refer to?

[Duthomhas]

It is complaining because your header file is not properly structured -- meaning that the compiler does not know what a ifstream is when it first encounters it.

It would work if you were to swap a couple of lines in your .cpp files:

using namespace std;
#include "Header.h" 

Rather than do that, though, you should correct your header:

header.h

#pragma once
#ifndef HEADERCODE_H
#define HEADERCODE_H

#include <fstream>

int factorial(int number);

void write_in_file(std::ifstream& instream, std::ofstream& outstream,int& user_integer);

#endif 

You need to #include the headers required for the function prototypes in header.h.
You need to use std:: namespace prefix for C++ library stuff used in header.h.
(Notice also I fixed line 2.)

Hope this helps.

[pfjf2]

Duoas, I love you. Now I can finally move on and learn some interesting stuff.