Trailing \ in %q[\a\b\c\] not treated as literal?

Richard_Lionheart · 20 November 2005 00:47

Hi,

I ran the following on a WinXP/SP2 machine:

F:\>ruby --version
ruby 1.8.2 (2004-12-25) [i386-mswin32]

F:\>ruby -e "puts %q[\a\b\c]"
\a\b\c

F:\>ruby -e "puts %q[\a\b\c\]"
-e:1: unterminated string meets end of file

F:\>

It seems to me the last \ shouldn't need to be escaped as \\, though that
does work. What's up?

···

--
TIA,
Richard

Mark_Hubbart1 · 20 November 2005 01:48

%q[foo] is equivalent to the single-quoted string literal 'foo'. In
the same way, the only escapable characters are backslash and the
character that ends the literal:

'Mark\'s string'
%q[square (\]) bracket]

A literal backslash in a single quoted string only needs to be escaped
where it might be confused as escaping the final quoting character,
like in your example.

HTH,
Mark

···

On 11/19/05, Richard Lionheart <NoOne@nowhere.net> wrote:

Hi,

I ran the following on a WinXP/SP2 machine:

F:\>ruby --version
ruby 1.8.2 (2004-12-25) [i386-mswin32]

F:\>ruby -e "puts %q[\a\b\c]"
\a\b\c

F:\>ruby -e "puts %q[\a\b\c\]"
-e:1: unterminated string meets end of file

F:\>

It seems to me the last \ shouldn't need to be escaped as \\, though that
does work. What's up?

Kevin_Olbrich · 20 November 2005 02:03

In a quoted string, a \cx is an escape for ctrl-x, so the \c\] is
interpreted as ctrl-] as the \] is an escape for the bracket in the quoted
string. Since there is no close bracket you get an error.

Try this...

puts %q[\a\b\\c\\]

And you get

\a\b\c\

_Kevin

···

-----Original Message-----
From: Richard Lionheart [mailto:NoOne@Nowhere.net]
Sent: Saturday, November 19, 2005 07:47 PM
To: ruby-talk ML
Subject: Trailing \ in %q[\a\b\c\] not treated as literal???

Hi,