std::cout
- C++ course
- Beginner
- Lesson 3/116
- 4 min
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.
Practice 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.
Starter code
#include <iostream>
int main() {
// Print two lines
return 0;
}Sample solution
#include <iostream>
int main() {
// Print two lines
std::cout << "Welcome" << std::endl;
std::cout << "Learning C++" << std::endl;
return 0;
}Expected output
Welcome Learning C++
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Output stream operator
std::cout ____ "Hello" << std::endl;std::cout << "Hello" << std::endl;Explanation: The << operator sends data to the output stream.
2 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 Correct answer
- It changes the output color
Explanation: std::endl adds a newline and flushes the buffer.
3 Match the output concepts
| Term | Meaning |
|---|---|
std::cout |
Output stream |
<< |
Output operator |
std::endl |
Newline and flush |
std:: |
Standard namespace |