C++ User Input

cin — Reading Input

cin (pronounced "see-in") reads input from the keyboard. It uses the extraction operator >>.

#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter your age: ";
    cin >> age;
    cout << "You are " << age << " years old." << endl;
    return 0;
}

Sample Run:

Enter your age: 25
You are 25 years old.

getline — Reading a Full Line

cin >> stops reading at the first whitespace. To read a whole line including spaces, use getline():

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

int main() {
    string fullName;
    cout << "Enter your full name: ";
    getline(cin, fullName);
    cout << "Hello, " << fullName << "!" << endl;
    return 0;
}

Sample Run:

Enter your full name: John Smith
Hello, John Smith!

Reading Multiple Inputs

#include <iostream>
using namespace std;

int main() {
    string name;
    int age;
    double height;

    cout << "Name: ";   cin >> name;
    cout << "Age: ";    cin >> age;
    cout << "Height (m): "; cin >> height;

    cout << "\n--- Profile ---" << endl;
    cout << "Name: "   << name   << endl;
    cout << "Age: "    << age    << endl;
    cout << "Height: " << height << "m" << endl;
    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int a, b;
    cout << "Enter first number: ";  cin >> a;
    cout << "Enter second number: "; cin >> b;

    cout << "Sum: "        << a + b << endl;
    cout << "Difference: " << a - b << endl;
    cout << "Product: "    << a * b << endl;
    return 0;
}

Summary

• cin >> variable reads a single word or number from the keyboard.
• getline(cin, str) reads an entire line including spaces.
• Use cin.ignore() when switching between cin >> and getline().