Input (cin)

Overview

Taking input allows programs to be interactive. `std::cin` reads input from the standard input stream (keyboard) and uses the extraction operator `>>`.

Syntax

cpp

#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter your age: ";
    cin >> age; // Reads an integer
    return 0;
}

Common Pitfalls

Using `cin >> stringVar` to read a full sentence. It will only capture the first word.
Input stream failure: If you ask for an `int` and the user types `"abc"`, `cin` enters a fail state and stops reading future inputs until cleared.

Interview Tips

Explain how `cin` handles whitespace. It stops reading when it hits a space, tab, or newline.
Know how to use `getline(cin, stringVar)` to read an entire line of text including spaces.

Real-World Example

Taking multiple inputs at once.

example

cpp

#include <iostream>
#include <string>
using namespace std;

int main() {
    string first, last;
    cout << "Enter first and last name: ";
    cin >> first >> last; // Chains input
    
    cout << "Hello, " << first << " " << last << "!" << endl;
    return 0;
}

Take C++ Quiz