Lesson 14 +10 XP

iostream: cout, cin, and endl

C++ talks to the outside world through streams. The header iostream gives us the most famous ones: cout, cin, and their helper endl.

The header

#include <iostream>
using namespace std;

iostream stands for "input/output stream" - one library, both directions.

cout: text going out

cout sends characters out to the console. It uses the insertion operator <<:

cout << "Hello world!";

The arrow points toward the screen: data flows out.

cin: input coming in

cin reads characters from the console. It uses the extraction operator >>:

int age;
cin >> age;

The arrow points from the keyboard into a variable: data flows in.

endl: end the line

endl writes a newline to the console (and flushes the output):

cout << "Done!" << endl;

The two streams together

#include <iostream>
using namespace std;

int main() {
    int number;
    cout << "Type a number: ";
    cin >> number;
    cout << "I got " << number << endl;
    return 0;
}

cin >> pulls the typed value in.
cout << pushes results back out.
Nothing gets lost along the way.

TL;DR

iostream is the header with the console streams.
cout << inserts data going out to the screen.
cin >> extracts data coming in from the keyboard.
endl moves to a new line and flushes.

iostream: cout, cin, and endl