give a c++ example using ofstream

Here is an example that uses ofstream to write data to a file:

#include <iostream>
#include <fstream>

using namespace std;

int main() {
    ofstream outputFile("output.txt"); // create an output stream to write to output.txt
    
    if (outputFile.is_open()) { // check if the file was successfully opened
        outputFile << "Hello, world!" << endl; // write data to the file
        outputFile << "This is a test." << endl;
        outputFile.close(); // close the file
        cout << "Data written to output.txt." << endl;
    } else {
        cout << "Error opening output.txt." << endl;
    }
    
    return 0;
}

This program creates an output stream to write data to a file called "output.txt". It then checks if the file was successfully opened, and if so, writes two lines of text to the file. Finally, it closes the file and prints a message indicating whether the data was successfully written.