Why use endl when I can use a newline character?

c++ string-formatting iostream buffering
Moshe picture Moshe · Sep 6, 2011 · Viewed 93.9k times · Source

Is there a reason to use endl with cout when I can just use \n? My C++ book says to use endl, but I don't see why. Is \n not supported as widely as endl, or am I missing something?

Answer

Armen Tsirunyan picture Armen Tsirunyan · Sep 6, 2011

endl appends '\n' to the stream and calls flush() on the stream. So

cout << x << endl;

is equivalent to 

cout << x << '\n';
cout.flush();

A stream may use an internal buffer which gets actually streamed when the stream is flushed. In case of cout you may not notice the difference since it's somehow synchronized (tied) with cin, but for an arbitrary stream, such as file stream, you'll notice a difference in a multithreaded program, for example.

Here's an interesting discussion on why flushing may be necessary.

Related questions

How to format a QString?

I'd like to format a string for Qt label, I'm programming in C++ on Qt. In ObjC I would write something like: NSString *format=[NSString stringWithFormat: ... ]; How to do something like that in Qt?

Read More
Format a Number to a specific QString format

I have a question about formatting a decimal number to a certain QString format. Basically, I have an input box in my program that can take any values. I want it to translate the value in this box to the …

Read More
how to format hex numbers using stringstream

I am trying to convert an unsigned short to its hexadecimal representation in uppercase and prefixed with 0's using stringstream. I can't seem to get the uppercase and 0's correct. here is what I have now: USHORT id = 1127; std::stringstream …

Read More