Using std::endl vs \n

In C++, std::endl and \n are both used to insert a newline character in the output stream, but they behave differently in terms of performance and functionality.

\n

The \n character is a newline character that is used to move the cursor to the next line. It is simple and efficient:

1#include <iostream>
2
3int main() {
4  std::cout << "Hello\nWorld"; 
5}

1Hello
2World

When you use \n, it just inserts a newline character into the stream without any additional operations.

std::endl

On the other hand, std::endl not only inserts a newline character but also flushes the output buffer. Flushing the buffer forces the output to be written to the terminal immediately, which can be useful for ensuring that all output is displayed, especially in debugging scenarios:

1#include <iostream>
2
3int main() {
4  std::cout << "Hello" << std::endl; 
5  std::cout << "World";
6}

1Hello
2World

The additional flush operation can slow down performance if used frequently in loops or high-performance applications. For example:

1#include <iostream>
2
3int main() {
4  for (int i = 0; i < 1000; ++i) {
5    std::cout << i << '\n'; 
6  }
7}

This loop will run faster than:

1#include <iostream>
2
3int main() {
4  for (int i = 0; i < 1000; ++i) {
5    std::cout << i << std::endl; 
6  }
7}

When to Use Each

• Use \n for most purposes where you just need a newline.
• Use std::endl when you specifically need to flush the output buffer.

Flushing can be important in situations where you need to ensure that the output is immediately visible, such as logging error messages or debugging.

By understanding the difference between \n and std::endl, you can write more efficient and effective C++ code.