C++ - User Input

Overview

Estimated time: 25–35 minutes

Read input from the terminal with std::cin and std::getline. Handle whitespace and type parsing.

Learning Objectives

• Use std::cin to read numbers and words.
• Use std::getline to read entire lines.
• Handle leftover newlines and input validation basics.

Prerequisites

• C++ - Comments

Reading numbers and words

#include <iostream>
#include <string>
int main(){
  int age; std::string name;
  std::cout << "Age: "; std::cin >> age;
  std::cout << "Name: "; std::cin >> name; // reads up to whitespace
  std::cout << name << " " << age << "\n";
}

Reading whole lines

#include <iostream>
#include <string>
int main(){
  std::string line;
  std::getline(std::cin, line);
}

Common Pitfalls

• Mixing operator>> with getline leaves a trailing newline in the buffer; consume it before getline.

Checks for Understanding

1. How do you read a full line with spaces?

Exercises

1. Prompt for first and last name separately using >> and then print the full name.
2. Prompt for a line of input and count the number of words.