In C++, you can write text files using the ofstream class, which provides a convenient way to write to a file as if it were a stream. To write text to a file, you first need to create an ofstream object and associate it with a file.

Here's an example of how to write text to a file:

#include <fstream>
#include <iostream>

int main() {
    std::ofstream outfile("example.txt");

    if (!outfile) {
        std::cerr << "Failed to open file for writing" << std::endl;
        return 1;
    }

    outfile << "Hello, world!" << std::endl;
    outfile << "This is a test" << std::endl;
    outfile.close();

    return 0;
}

In this example, we first create an ofstream object called outfile and associate it with the file "example.txt". We then check to make sure that the file was opened successfully, and if not, we print an error message and return from the program.

We then write two lines of text to the file using the stream insertion operator (<<) and the std::endl manipulator to add a newline character. Finally, we close the file using the close() method.

When the program is run, it will create a new file called "example.txt" in the current working directory, and write the two lines of text to it.

Note that when you write to a file using ofstream, the text is written to a buffer, which may not be immediately written to the file on disk. To ensure that the data is written to the file, you can either call the flush() method or close the file using the close() method, as shown in the example above.

You can also use ofstream to append text to an existing file by specifying the std::ios_base::app flag when opening the file:

std::ofstream outfile("example.txt", std::ios_base::app);

This will open the file in "append" mode, which means that any text written to the file will be added to the end of the file, rather than overwriting the existing contents.

In summary, to write text to a file in C++:

1. Create an ofstream object and associate it with a file using the file name.
2. Check to make sure that the file was opened successfully.
3. Write text to the file using the stream insertion operator (<<) and the std::endl manipulator to add a newline character.
4. Close the file using the close() method when you're done writing to it.