std::cout

Learn to print text and variables with std::cout.

std::cout

std::cout is the standard output stream; it prints text to the screen. The << operator sends data to the output stream. Multiple values can be chained together.

For example, std::cout << "Score: " << 95 << std::endl; prints Score: 95 and ends the line. std::endl both adds a newline and flushes the buffer.

The std:: prefix in std::cout marks the standard namespace; it is defined in the iostream header.

std::endl and \n

There are two ways to move to a new line: std::endl and "\n". Both move the cursor to the next line.

std::endl additionally flushes the buffer: it writes the output to the screen immediately. "\n" only adds a newline character and is faster.

When printing many lines, "\n" is preferred for performance; use std::endl when output must appear immediately. You can mix both in the same program.

Exercise Print two lines

Add two std::cout lines inside main. The first line should print Welcome, the second Learning C++. End each line with std::endl.

Show example solution

#include <iostream>

int main() {
    // Print two lines
    std::cout << "Welcome" << std::endl;
    std::cout << "Learning C++" << std::endl;
    return 0;
}

Test yourself

Output stream operator

std::cout ____ "Hello" << std::endl;

Show answer

std::cout << "Hello" << std::endl;

What does std::endl do?
```
std::cout << "Line 1" << std::endl;
```
- It only adds a blank line
- It terminates the program
- It adds a newline and flushes the buffer
- It changes the output color
Show answer

It adds a newline and flushes the buffer — std::endl adds a newline and flushes the buffer.
Match the output concepts

std::cout

Output stream
<<

Output operator
std::endl

Newline and flush
std::

Standard namespace

Next lesson: std::cin

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