File Handling in C++ | Read and Write Text Files

📂 File Handling in C++

File handling in C++ is performed using streams from the <fstream> library. You can use it to read from or write to text files. Commonly used classes are ofstream for writing and ifstream for reading.

📘 Key File Stream Classes

• ifstream: Read from files
• ofstream: Write to files
• fstream: Read and write from/to files

📄 C++ Code: Write and Read a Text File

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

int main() {
    // Writing to a file
    ofstream writeFile("example.txt");
    if (writeFile.is_open()) {
        writeFile << "Hello, world!" << endl;
        writeFile << "This is a text file." << endl;
        writeFile.close();
    } else {
        cout << "Unable to open file for writing." << endl;
    }

    // Reading from the file
    ifstream readFile("example.txt");
    string line;
    cout << "Reading from file:" << endl;
    if (readFile.is_open()) {
        while (getline(readFile, line)) {
            cout << line << endl;
        }
        readFile.close();
    } else {
        cout << "Unable to open file for reading." << endl;
    }

    return 0;
}
    

📝 Sample Output

Reading from file:
Hello, world!
This is a text file.

🧠 Explanation

• ofstream creates or overwrites a file and writes text into it.
• ifstream reads the file line by line using getline().
• Always check if a file is open before reading or writing.
• Use close() to close the file after operations are done.

File I/O is essential for programs that need to save data persistently. It's used in databases, logging, configuration, and more.