Thread: File I/O Question

I've read the tutorial on this site, but I am not quite sure what is means. Ex. Say if I make a Readme type file or help file in notepad, could I implement that into my program. Is that what file i/o is used for? Not sure what it means.

It means like instead of printing to cout (stdout, the screen) you can print to a file; and instead of using stdin (cin) you can read from a file.

OH, ok. I was way off. Thanks for the reply.

think of it this way: how does a store save information about their sales for the day when they shut the computers off? how does a game know where you left off when you exit?

basically, you can write information to a file to save it for later, or you can give it a file to parse data from, or a whole bunch of things... sure stores use databases, but it's (very) vaguely the same idea...

for example:

Code:

#include<iostream>
#include<fstream>

int main()
{
	int num;
	
	std::cout<<"What do you want to do:\n"
		<<" 1. Save a number\n"
		<<" 2. Retrieve the number\n";
	
	std::cin>>num;
	std::cin.ignore(1);

	if(num==1)
	{
		std::cout<<"Enter the number: ";
		std::cin>>num;
		std::cin.ignore(1);
		
		std::ofstream file("test.in",std::ios::trunc);
		file<<num;
		file.close();
	}
	else if(num==2)
	{
		std::ifstream file("test.in");
		
		if(!file)
		{
			std::cerr<<"File not available, exiting\n";
			exit(1);
		}
		
		file>>num;
		file.close();
		std::cout<<"The last number was: "<<num<<std::endl;
	}
	else
	{
		std::cerr<<"Invalid option, exiting\n";
		exit(2);
	}
}