C++ provides facilities for accepting input from a user. We can think of the standard input as our keyboard. A simple example accepting one integer number and printing it out is:
#include <iostream>
int main()
{
std::cout << "Please enter a number and press enter: ";
int x = 0;
std::cin >> x;
std::cout << "You entered: " << x;
}
The std::cin is the standard input stream, and it uses the >> operator to extract what has been read into our variable. The std::cin >> x; statement means: read from a standard input into a x variable. The cin object resides inside the std namespace. So, std::cout << is used for outputting data (to a screen) and std::cin >> is used for inputting the data (from the keyboard).
We can accept multiple values from the standard input by separating them with multiple >> operators:
#include <iostream>
int main()
{
std::cout << "Please enter two numbers separated by a space and press enter: ";
int x = 0;
int y = 0;
std::cin >> x >> y;
std::cout << "You entered: " << x << " and " << y;
}
We can accept values of different types:
#include <iostream>
int main()
{
std::cout << "Please enter a character, an integer and a double: ";
char c = 0;
int x = 0;
double d = 0.0;
std::cin >> c >> x >> d;
std::cout << "You entered: " << c << ", " << x << " and " << d;
}