Input and Output

NOTE: This article is part of a C++ guide, therefore only C++ code will be displayed.

Standard Input / Output

To interact with the user through the console we need to include a library. The library we will use in this case is <iostream>. This means that from now on the structure of a program should look like this:

#include <iostream>
using namespace std;

int main(){
    // our code goes here
}

Output

When outputing some text to the standard out(also known as stdout) we can use the following syntax:

cout << thing << endl;

here thing represents any data we want to output (be it a string, variable, number, etc.) here endl represents the new line character "\n", meaning the following line is equivalent:

cout << thing << "\n";

We can output multiple things by adding more << operators:

cout << thing1 << thing2 << thing3 << "\n";

These can also be separated into multiple lines like this:

cout << thing1;
cout << thing2; 
cout << thing3;
cout << "\n";

or any combination:

cout << thing1 
cout << thing2 << thing3;
cout << "\n";

Input

Input is similar in syntax to cout, but the operators go in reverse(i.e. cout has <<, cin has >>). Example:

int num;
int x;
cin >> num;
cin >> x;

int num;
int x;
cin >> num >> x;

The values gotten from stdin have to be separated by white space. This means that the following inputs would be valid for the shown example:

1 2

1          2

1
2

Example program

#include <iostream>
using namespace std;

int main() {
    int a,b;
    int c;

    cin >> a;
    cin >> b >> c;
    cout << "The sum of these three numbers is " << a + b + c << endl;
    int multiplied_numbers = a * b * c;
    cout << "The multiplication of these three numbers is ";
    cout << multiplied_numbers << "\n";
}