C++ Day 19

 Today we’re going to talk about file handling in C++. You’ll learn how to read from and write to files using a special library called fstream.

To get started, you’ll need to include a header file at the beginning of your code.

#include

Next let’s talk about file streams. There are three main types you’ll work with:

• ofstream for writing to files

• ifstream for reading from them

• fstream, which allows you to do both reading and writing in one stream.

If you want to write something to a file, here’s a simple example:

#include
#include

int main() {
    std::ofstream fout("example.txt");
    fout << "Hello, this is Day 19!\n";
    fout.close();
    return 0;
}

And if you want to read from a file, you’d do it like this:

#include
#include
using namespace std;

int main() {
    std::ifstream fin("example.txt");
    string line;
    while (getline(fin, line)) {
        std::cout << line << endl;
    }
    fin.close();
    return 0;
}

There are also different opening modes you can use, such as ios::in for reading and ios::out for writing. Some others include ios::app for appending, ios::binary for binary files, and ios::trunc, which truncates files.

It’s also important to check if a file opened correctly. For instance:

std::ifstream fin_stream("data.txt");
if (!fin_stream) {
    std::cout << "File could not be opened!";
}

For practice, you could try creating a program that saves what the user types into a file, then reads that back and displays it on the screen. And remember, it’s a good habit to close your files using .close() when you’re done to avoid any issues. Happy coding!