C++ File I/O

📁 C++ File I/O – Read and Write Files Easily

Want to save your data even after the program ends? That’s where File I/O comes in! 📄

Using <fstream>, C++ lets you read from and write to files using just a few lines of code. It’s like giving your program memory!

📚 Required Header

#include <fstream>

This header gives you access to three handy file stream classes:

• ofstream – for writing files
• ifstream – for reading files
• fstream – for both reading and writing

📝 Example: Writing to a File

#include <iostream>
#include <fstream>
using namespace std;

int main() {
    ofstream myFile("example.txt"); // Create and open file
    myFile << "Hello, file world!\n"; // Write to file
    myFile.close(); // Always close the file
    return 0;
}
  

📖 Example: Reading from a File

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main() {
    ifstream myFile("example.txt"); // Open file for reading
    string line;
    while (getline(myFile, line)) {
        cout << line << endl; // Print each line
    }
    myFile.close();
    return 0;
}
  

⚙️ File Modes

You can open files in different modes using fstream flags:

• ios::in – Read
• ios::out – Write
• ios::app – Append
• ios::binary – Binary mode

🔐 Always Close Files

Use myFile.close() to avoid memory leaks and ensure data is saved properly.

✅ Summary

• File I/O helps store data even after the program ends.
• Use ofstream to write and ifstream to read.
• Always close the file when you’re done!