Difference between \n and \r?

carriage-return, newline

Solution

In terms of ascii code, it's 3 -- since they're 10 and 13 respectively;-).

But seriously, there are many:

- in Unix and all Unix-like systems, `\n` is the code for end-of-line, `\r` means nothing special

- as a consequence, in C and most languages that somehow copy it (even remotely), `\n` is the standard escape sequence for end of line (translated to/from OS-specific sequences as needed)

- in old Mac systems (pre-OS X), `\r` was the code for end-of-line instead

- in Windows (and many old OSs), the code for end of line is 2 characters, `\r\n`, in this order

- as a (surprising;-) consequence (harking back to OSs much older than Windows), `\r\n` is the standard line-termination for text formats on the Internet

- for electromechanical teletype-like "terminals", `\r` commands the carriage to go back leftwards until it hits the leftmost stop (a slow operation), `\n` commands the roller to roll up one line (a much faster operation) -- that's the reason you always have `\r` before `\n`, so that the roller can move while the carriage is still going leftwards!-) Wikipedia has a more detailed explanation.

- for character-mode terminals (typically emulating even-older printing ones as above), in raw mode, `\r` and `\n` act similarly (except both in terms of the cursor, as there is no carriage or roller;-)

In practice, in the modern context of writing to a text file, you should always use `\n` (the underlying runtime will translate that if you're on a weird OS, e.g., Windows;-). The only reason to use `\r` is if you're writing to a character terminal (or more likely a "console window" emulating it) and want the next line you write to overwrite the last one you just wrote (sometimes used for goofy "ascii animation" effects of e.g. progress bars) -- this is getting pretty obsolete in a world of GUIs, though;-).

Problem

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