Keith Devens .com - Weblog: String escaping behavior

Friday, November 4, 2005

String escaping behavior

Which do you think is the more appropriate behavior for escapes that aren't escapes in your programming language: Say you have an escape that doesn't mean anything, like "\g". Should your programming language turn that into "g" or leave it as just "\g"?

$>python -c "print \"\g\""

\g



$>perl -e "print \"\g\""

g



$>ruby -e "print \"\g\""

g



$>php -r "print \"\g\";"

\g



$>lua -e "print \"\g\""

g



$>cat test.c

#include<stdio.h>

int main(){printf("\g");}



$>gcc test.c

test.c:2:19: warning: unknown escape sequence '\g'



$>a

g



$>MzScheme -e "(display \"\g\")"

Welcome to MzScheme version 299.400...

#f::9: read: unknown escape sequence \g in string

> ^Z

Anyone want to test C# and Java for me (since I don't have the interpreters on my system)? More importantly, want to tell me which you prefer? What does JSON do? (Update: it's not defined in JSON, but an alert("\g") in Firefox's JS console gives 'g').

Permalink | 4 Comments | Tags: Programming | id 7536

02:39 (utc-5)
edited: 02:45 (utc-5)

Comments

DJ Hannibal wrote:

C# exhibits the same behaviour as C/C++, which you can generally count on. Java should throw a compiler error, but who knows with that obtuse, daft, and inane language.

∴ DJ Hannibal | 4-Nov-2005 9:15am est | #8606

Anonymous wrote:

My copy of C# from VS2005:
Program.cs(11,31): error CS1009: Unrecognized escape sequence
No runtime behavior since the build fails

∴ Anonymous | 4-Nov-2005 9:51am est | #8608

Davd wrote:

Wow, I'm really upset at Python. I love Python, but clearly an escaped character that doesn't need to be escaped is just a regular character. You should be able to escape every character in a string and just get that string back.

What is "escaping" if not "take the next character literally".

Consider it this way... how to you get a "" in the result string. Shouldn't you only get a "" from "\". The first "" in any situation is a control character and should get eaten.

Wow... this is a very crushing revelation. As my regexps get more complex, I'm going to have to watch out for this.

∴ Davd | 4-Nov-2005 11:43am est | #8609

What is "escaping" if not "take the next character literally".

It doesn't mean that at all. "\n" means "newline", "\b" means "Bell", "\uEF29" means Unicode character... and so on.

You should be able to escape every character in a string and just get that string back.

Huh? No, you'd wind up with a string full of newlines and tabs and such.

∴ Keith | 5-Nov-2005 1:17pm est | http://keithdevens.com/ | #8618

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