Programs often require values to be provided while they are running. In C++, the standard input stream is represented by std::cin, which reads data entered through the keyboard.

This example demonstrates how to read an integer from the user and display the entered value using the standard output stream.

Source Code #

#include <iostream>

int main()
{
    int number;

    std::cout << "Enter a number: ";
    std::cin >> number;

    std::cout << "You entered: " << number << '\n';

    return 0;
}

Output #

Enter a number: 25
You entered: 25

Explanation #

• int number; declares an integer variable that stores the value entered by the user.
• std::cout << "Enter a number: "; displays a prompt before waiting for input.
• std::cin is the standard input stream object used to read data from the keyboard.
• The extraction operator (>>) reads characters from the input stream, converts them to the required data type, and stores the result in number.
• std::cout << "You entered: " << number << '\n'; displays the value stored in the variable.
• return 0; terminates the program and returns a success status to the operating system.