File.cpp

#include <iostream>
#include <string>
#include <fstream>							//allows use of file stream
#include <sstream>

int main()
{
														//	constructor for file streams implements the open() function
														//	example		-> ifs.open("foo.txt") = ifs("foo.txt")
														//std::ios::app means write data from the end of the file

	std::ofstream	ofs("foo.txt", std::ios::app);		//	ofstream		-> write only	->	creates file if file does not exist
	std::ifstream	ifs("foo.txt");						        //	ifstream		-> read only	->	reads from file if it exists

	std::ostringstream oss;
	std::string str;

	//if file is empty write to it
	if (ofs.is_open() && (ifs.peek() == std::ifstream::traits_type::eof())){
		std::cout << "File was written to" << "\n";
		ofs << "Yay... Files!!!!" << std::endl;
	}
	//if file has already been written to, don't write to it
	else if (ofs.is_open()){
		std::cout << "File has already been written to" << std::endl;
	}
	//something bad happened
	else {
		std::cout << "Error occured while outputting to file" << std::endl;
	}

	//close to prevent further access
	ofs.close();
	//sets position to beginning of "foo.txt" and
	//also calls std::ifstream::clear()
	//which resets eof bit
	ifs.seekg(0, std::ios::beg);

	std::cout << "\nReading from file\n";
	std::cout << "-------------------" << std::endl;

	//if the file isn't empty then print it
	if (ifs.peek() != std::ifstream::traits_type::eof())
	{
		//using ostringstream because we are only outputting to a string
		while (std::getline(ifs, str))
		{
			oss << str << "\n";
		}

		std::cout << oss.str() << std::endl;
	}
	else
	{
		//should never run
		std::cout << "File was empty" << std::endl;
	}

	std::cin.get();
}