Shortest string expressions stable under deleting quotes

Question

Forgetting quotes can lead to certain problems. For example, in Scala the two expressions:

"("+("+")+(")+(")+")" ("+("+")+(")+(")+")

differ only in starting and ending quotes, but they respectively yield the result:

(+)+() +()+()+

But this expression in scala almost has the desired property:

def m="+m+" ""+m+""

Your task is to write the shortest expression surrounded with quotes, such that if we remove the outer quotes, the expression still returns the same string.

Key points:

Your language must support "..." as string literals
The program has to contain at least three characters
You are not allowed to define a context outside of the quotes themselves (as I did for m)
You are not allowed to use other delimiters for strings, e.g. no """, no '.
Both expressions should return strings.
Shortest code wins (counting the quotes themselves)

return or output? can we do either? Also, how is "quine" related to this? — Justin
– Justin, Commented Jan 9, 2014 at 17:09
@Howard I changed only the title to reflect the content of the question. — boothby
– boothby, Commented Jan 9, 2014 at 19:08
@Quincunx: Both return or output, but it should be a string. I added a line to describe it. The relation with quines is that solutions somehow encode a part of the program in a string. Ok I agree it's more a far-distant cousin relationship. — Mikaël Mayer
– Mikaël Mayer, Commented Jan 10, 2014 at 6:47

MvG · Accepted Answer · 2014-01-09 18:00:31Z

C (4 chars)

The expression

""""

satisfies the minimal requirement of three characters. It encodes the empty string, no matter even if you omit one level of quotes:

""

If you want the resulting string to be at least three characters, here is an expression of length 10 which results in three characters of string, namely three spaces:

"" " " " "

If you don't like spaces either, here are four printable characters in a length 12 expression:

""/**/"/**/" "/**/"/**/

Putting these expressions into a small program:

#include <stdio.h> #define CASE(s) printf("'%s'\n", s) int main() { CASE(""""); CASE(""); CASE("" " "); CASE(" " ); CASE(""/**/"/**/"); CASE("/**/"/**/); }

Output:

'' '' ' ' ' ' '/**/' '/**/'

MvG · Accepted Answer · 2014-01-09 19:22:32Z

4

Shell (3 chars)

"w" w

Both execute the command w.

answered Jan 9, 2014 at 19:22

MvG

7965 silver badges13 bronze badges

3

\$\begingroup\$ Seriously?!? How many seconds of my life have been wasted typing who? \$\endgroup\$

boothby
– boothby

2014-01-10 06:49:57 +00:00
Commented Jan 10, 2014 at 6:49
1

\$\begingroup\$ The question doesn't ask you to execute a command, it asks you to return a string. \$\endgroup\$

Peter Taylor
– Peter Taylor

2014-01-10 10:47:51 +00:00
Commented Jan 10, 2014 at 10:47
1

\$\begingroup\$ @PeterTaylor: The way I read it, it asks for an expression which can be interpreted in two ways with the same meaning either way. So the expression above will do that. It is when you type that expression as the sole argument on an otherwise empty command line that the expression gets interpreted as a command name and executed. You could just as well use that expression as an argument to something else, e.g. to echo. \$\endgroup\$

MvG
– MvG

2014-01-10 11:00:03 +00:00
Commented Jan 10, 2014 at 11:00
\$\begingroup\$ @boothby: assuming your typing speed is the same as mine, about 0.15 seconds per invocation of w. \$\endgroup\$

Joe Z.
– Joe Z.

2014-01-10 16:49:30 +00:00
Commented Jan 10, 2014 at 16:49
\$\begingroup\$ I updated the question: "Both programs should return strings." \$\endgroup\$

Mikaël Mayer
– Mikaël Mayer

2014-01-11 12:02:57 +00:00
Commented Jan 11, 2014 at 12:02

Add a comment |

Doorknob · Accepted Answer · 2014-01-10 21:54:02Z

JavaScript, 28 27 15 12 (6 if result can be non-string (still works with output))

This one's pretty interesting.

"+"*1+"+"+""

The basic explanation is that "string" * 1 is NaN, and +"string" is also NaN. Therefore, it results in the string "NaN+" with or without the outside quotes.

For further explanation, it gets parsed as ("+" * 1) + ("+") + ("") with the outside quotes, and (+ "*1+") + "+" without.

The version that works if the output can be non-string:

"+"*""

Which does work when outputting (as JavaScript is weakly typed):

alert("+"*"") // NaN alert(+"*") // NaN

Old version:

"+".replace(/./,NaN)+"+"+""

With the quotes outside, it is parsed as

("+".replace(/./, NaN)) + ("+") + ("") "NaN" + "+" + "" "NaN+"

Without the quotes, it gets parsed as

(+".replace(/./,NaN)+") + ("+") // +"any string" evaluates to NaN NaN + "+" "NaN+"

primo · Accepted Answer · 2014-01-09 18:09:19Z

3

Perl - 4 bytes

"$~"

Test program:

print"$~"; print$~;

Ouput:

STDOUT STDOUT

answered Jan 9, 2014 at 18:09

primo

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1

\$\begingroup\$ Also works with many other single-character special variables in Perl. Notably,$0, $;, $/, $: and $^ also have a non-empty string as their default value. (So does $", but "$"" is a syntax error.) \$\endgroup\$

Ilmari Karonen
– Ilmari Karonen

2015-04-05 11:49:15 +00:00
Commented Apr 5, 2015 at 11:49

Add a comment |

Doorknob · Accepted Answer · 2014-01-10 13:47:15Z

3

JavaScript, 40

"(f=function (){return'(f='+f+')()'})()"

When you remove the quotes, it becomes an immediately invoked function expression, and this function happens to return '(f='+f+')()', which is the entirety of the string. (Absuing Function#toString. ;))

answered Jan 10, 2014 at 13:47

Doorknob

72.1k20 gold badges146 silver badges393 bronze badges

\$\begingroup\$ Nice usage of quine. Could you do the same without using secondary quotes? \$\endgroup\$

Mikaël Mayer
– Mikaël Mayer

2014-01-10 14:00:35 +00:00
Commented Jan 10, 2014 at 14:00
\$\begingroup\$ @Mikaël Probably not, since I can't have double quotes inside double quotes :-P \$\endgroup\$

Doorknob
– Doorknob

2014-01-10 14:01:55 +00:00
Commented Jan 10, 2014 at 14:01
\$\begingroup\$ @MikaëlMayer I made a version (completely different one) without secondary quotes! :D codegolf.stackexchange.com/a/18188/3808 \$\endgroup\$

Doorknob
– Doorknob

2014-01-10 14:14:57 +00:00
Commented Jan 10, 2014 at 14:14

Add a comment |

Timtech · Accepted Answer · 2014-01-12 16:40:39Z

huh?, 7

"Ouch!"

It works because both "Ouch!" and Ouch! are both invalid files, so the interpreter will return Ouch!

flonk · Accepted Answer · 2014-01-13 10:07:24Z

Update: Python (12 chars)

program

""+"+""+"+"" "+"+""+"+"

both giving

'++'

Python (28 chars)

program

"".__str__()+".__str__()+""" ".__str__()+".__str__()+""

both giving

'.__str__()+'

Python (38 chars)

program

"".replace("+","+")+".replace("+","")" ".replace("+","+")+".replace("+","")

both giving

'.replace(,)'

yes that was also new to me, it also allows for a more compact solution (see edit). — flonk
– flonk, Commented Jan 10, 2014 at 13:40

Community · Accepted Answer · 2020-06-17 09:04:33Z

Befunge 98 - 3, 4, 6, 17

In these programs, I'll assume you just want to get a string, but you don't care if the program terminates. In other words, you want a code snippet that can be placed in the code somewhere. (Note: in Befunge, whatever is on the stack is a string. It is also a number)

This code snippet must be placed on the first part of the first line.

"g"

When the quotes are removed, g acts like 00g, so it pushes a g. Either way, it pushes a g.

""""

Works in Befunge 93 as well; it always pushes nothing.

This one is more interesting

""z"z"

It will always push z. z is a no-op so although the IP executes the command, it does nothing (I could have used , but z is more interesting).

This one only has one set of ", and is quine-like:

">:0g\1+:f`1+jb<"

It always pushes the contents of the string, but when the quotes are removed, it does it in a quine-like way. This must be placed on the first part of the first line, but adjustments can be made to put it elsewhere

I updated the question so that it removes the first case: "Both programs should return strings." — Mikaël Mayer
– Mikaël Mayer, Commented Jan 11, 2014 at 12:03
@MikaëlMayer No, the first case is not removed. Both programs "g" and g return strings, one is g, and the other is g. — Justin
– Justin, Commented Jan 12, 2014 at 0:58

goric · Accepted Answer · 2014-01-10 20:29:42Z

PowerShell, 4 chars

"$?" $?

Output:

TRUE TRUE

This uses the automatic variable $?, which is a Boolean containing the execution status of the last run command. The only effect of wrapping it in quotes is that it is converted to a string prior to being printed, which is a transparent operation.

I updated the question: "Both programs should return strings." — Mikaël Mayer
– Mikaël Mayer, Commented Jan 11, 2014 at 12:03

Ilmari Karonen · Accepted Answer · 2014-01-11 14:25:08Z

GolfScript: 16 chars

OK, since my 3-char solution "1" has been disqualified by a rules change, here's the straightforward solution in GolfScript:

"{`[46 126]+}.~"

With the quotes, this is just a double-quoted string literal. Without the quotes, it's a quine. The only slightly trickly part is that, to literally comply with the rule prohibiting alternative string delimiters, I have to encode the string '.~' as an array of ASCII codes [46 126] instead.

I updated the question: "Both programs should return strings." — Mikaël Mayer
– Mikaël Mayer, Commented Jan 11, 2014 at 12:03

Community · Accepted Answer · 2020-06-17 09:04:33Z

Scala REPL (10 chars)

"0+"++"+0" 0+"++"+0

are both returning:

0++0 0++0

Explanation: In the first case ++ treats the left string as a sequence of chars and concatenates the next sequence of chars and rebuilds a string. In the second case, + converts the first and last 0 to strings.

Note that everything is even a palindrom.

Python 3.8 (pre-release), 11 9 7 bytes

""#"*0"

Try it online!

The expression with quotes is ""#"*0" which is just "" as the comment is ignored. The expression without quotes is "#"*0 which is the empty string by product.

Community · Accepted Answer · 2020-06-17 09:04:33Z

0

Python (8 characters)

""""""""

and

""""""

both return empty string
Is based on idea of MvG

edited Jun 17, 2020 at 9:04

CommunityBot

1

answered Jan 19, 2014 at 17:54

AMK

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Add a comment |

sergiol · Accepted Answer · 2017-11-17 00:10:08Z

0

Tcl, 1, 3

1 "1"

Try it online!

Explanation: In Tcl, "quoting is a tool, not a rule"

answered Nov 17, 2017 at 0:10

sergiol

4,1551 gold badge17 silver badges37 bronze badges

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Khuldraeseth na'Barya · Accepted Answer · 2017-11-17 01:53:19Z

TI-BASIC, 6 bytes

""→Str1:" "→Str1:

Both of these end up storing an empty string to Ans (and to Str1). The second works because storing to a variable also stores to Ans.

I also found another 6-byter:

"":":" ":":

Both of these will return ":".

I have checked every shorter chain matching "[":]{0-3}", and none meet the specifications.

Stack Exchange Network

Shortest string expressions stable under deleting quotes

15 Answers 15

C (4 chars)

Shell (3 chars)

JavaScript, 28 27 15 12 (6 if result can be non-string (still works with output))

Perl - 4 bytes

JavaScript, 40

huh?, 7

Update: Python (12 chars)

Python (28 chars)

Python (38 chars)

Befunge 98 - 3, 4, 6, 17

PowerShell, 4 chars

GolfScript: 16 chars

Scala REPL (10 chars)

Other interesting solution using blocks (55 chars)

Python 3.8 (pre-release), 11 9 7 bytes

Python (8 characters)

Tcl, 1, 3

TI-BASIC, 6 bytes

Hot Network Questions

Shortest string expressions stable under deleting quotes

15 Answers 15

C (4 chars)

Shell (3 chars)

JavaScript, 28 27 15 12 (6 if result can be non-string (still works with output))

Perl - 4 bytes

JavaScript, 40

huh?, 7

Update: Python (12 chars)

Python (28 chars)

Python (38 chars)

Befunge 98 - 3, 4, 6, 17

PowerShell, 4 chars

GolfScript: 16 chars

Scala REPL (10 chars)

Other interesting solution using blocks (55 chars)

Python 3.8 (pre-release), 11 9 7 bytes

Python (8 characters)

Tcl, 1, 3

TI-BASIC, 6 bytes

Related

Hot Network Questions