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Strings are enclosed in double quotes $\rm \LQT ... \RQT$. Within a string, a sequence '\c' denotes the two characters '\' and 'c', with the exception of the following:

\t tab
\n newline

The two-character sequences $\rm \backslash n$ and $\rm \backslash t$ are called $\it escape\ sequences$. Other escape sequences like $\rm \backslash r$ (carriage return) are not part of Cool. These two special escape sequences should not be interpreted or transformed by the lexer; they are handled by the $\rm IO$ module and the run-time system.

A newline character may not appear in a string:

"This is not
OK"

A string may contain embedded double quotes, so long as they are escaped. The following is a valid Cool string:

"David St. Hubbins said, \"It's such a fine line between stupid, and clever.\""

Note that Cool's interpretation of $\rm \backslash "$ may not be what you are expecting. The two-character sequence $\rm \backslash "$ (which is not an escape sequence) does not become $\rm "$ in any sense. Instead, it stays $\rm \backslash "$. This is different from most other languages, but simplifies lexing and interpreting. Example:

class Main inherits IO {
	main() : Object {
		out_string("She said, \"Hello.\"\n")
	} ;
} ;

• Output: $\rm She\ said,\ \backslash \LQT Hello.\backslash \RQT$

A string may not contain EOF; strings cannot cross file boundaries. A string may not contain NUL, the character with ASCII value 0. The lexer must reject source text that contains malformed strings.

A string may contain the two-character sequence $\rm \backslash 0$ (backslash zero). However, that sequence does not have any special meaning -- it just yields a backslash followed by a zero inside the string.

The single character with converted integer value zero (the NUL) is not allowed. Any other character may be included in a string.

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