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

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

#include <fstream>
#include <iostream>
#include <string>

int main() {
    std::ifstream infile("example.txt");

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

    std::string line;

    while (std::getline(infile, line)) {
        std::cout << line << std::endl;
    }

    infile.close();

    return 0;
}

In this example, we first create an ifstream object called infile 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 define a std::string called line and use the std::getline() function to read each line of the file into this string. The std::getline() function returns false when it reaches the end of the file, so we use it as the condition for a while loop to read all the lines of the file. Inside the loop, we simply output the line to the console using std::cout.

Finally, we close the file using the close() method.

When the program is run, it will open the file "example.txt" and read all the lines from it, outputting them to the console.

You can also use ifstream to read text from a file into a character array:

#include <fstream>
#include <iostream>

int main() {
    std::ifstream infile("example.txt");

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

    const int MAX_LENGTH = 1024;
    char buffer[MAX_LENGTH];

    while (infile.getline(buffer, MAX_LENGTH)) {
        std::cout << buffer << std::endl;
    }

    infile.close();

    return 0;
}

In this example, we define a character array called buffer with a maximum length of 1024 characters. We use the std::ifstream::getline() method to read each line of the file into this buffer, and output it to the console using std::cout.

Note that in this case, we're using the std::ifstream::getline() method, which reads the text up to a newline character and discards it, so we don't need to add a newline character when outputting the text to the console.

In summary, to read text from a file in C++:

1. Create an ifstream object and associate it with a file using the file name.
2. Check to make sure that the file was opened successfully.
3. Read text from the file using the std::getline() or std::ifstream::getline() function into a std::string or character array.
4. Close the file using the close() method when you're done reading from it.