Input & Output

Input and output are how your program talks to the world. In C++, you use cout to send text to the console and cin to read input from the user. You also have endl to insert a new line and flush the output buffer.

cout and cin

cout uses the << operator — think of it as an arrow pointing toward cout, meaning data flows to the console. cin uses the >> operator — data flows from the keyboard into your variable.

The endl (end line) moves the cursor to the next line. You can also use \n inside a string to do the same thing, but endl also flushes the output, which can be helpful.

#include <iostream>
using namespace std;

int main() {
  string name;
  int age;

  cout << "Enter your name: ";
  cin >> name;

  cout << "Enter your age: ";
  cin >> age;

  cout << "Hello, " << name << "!" << endl;
  cout << "You are " << age << " years old." << endl;
  cout << "Nice to meet you!";
  return 0;
}

There is a catch with cin — it stops reading at whitespace. So if you type "Bilal Mubarak" and press enter, only "Bilal" will be stored in the string. To read a whole line including spaces, use getline(cin, variable) instead. We will cover that in a later lesson.