Carriage return and Line feed are both single characters that can be represented as '\r' and '\n' respectively.
This works in a string constant ("Something\r\nNext line") or as a single character (assert(*strchr("abc\r\ndef", '\r') == '\r')).
On an entirely different note, I have found that it can make string constants with like breaks in them easier to read if you do something like this:
const char *message =
"First line ...\r\n"
"Second line ...\r\n"
"Third line.";
The compiler will concatenate these strings at compile time and this way is typically much more readable.
For your reference, the common available special characters are:
null byte: \0
bell character: \a
backspace: \b
horizontal tab: \t
formfeed: \f
newline: \n
carriage return: \r
Also note that since \ is used to denote these characters, to get an actual backslash in a string or as a single character, you have do use 2 (as in "\\" or '\\').
Hope this helps,
Alex