Input and Output

There is one last topic to discuss before moving onto the C++ Object Oriented Programming Lesson.

You have already seen how to call a function and then output the results to the terminal using cout. As an example:

std::cout << distance(3, 4, 5);

But how do you get user input from the terminal? Or how do you input data from a file into your program or write out your results to a file?

cin

Much like the Standard Library provides a function for outputting to the terminal, the library also provides a function for reading in data from the terminal.

This code demonstrates how to use cin:

#include <iostream>
#include <vector>

using namespace std;

int main() {

    int integerone; 
    int integertwo;

    // declare array and assign values
    cout << "Enter an integer between 1 and 100" << endl;
    cin >> integerone;

    cout << "Enter another integer between 1 and 100" << endl;
    cin >> integertwo;

    // output the difference
    cout << "The difference between your two numbers is: ";
    cout << integerone - integertwo << endl;


    return 0;
}

To see how this code works, you will need to put the code into a .cpp file and run the program locally. The classroom playground does not allow for user input.

Next, you will learn how to input data from an external file.