Reverse a string "in place"

[Water Cooler v2]

I've asked myself this question in the past but couldn't afford more
time to it (I program other languages for my bread and butter), so I'll
ask now since it's never too late.

What does the qualifier "in place" mean here? Does that mean without
using additional memory?

[Richard Heathfield]

Re: Reverse a string "in place"

Water Cooler v2 said:
[color=blue]
> I've asked myself this question in the past but couldn't afford more
> time to it (I program other languages for my bread and butter), so I'll
> ask now since it's never too late.
>
> What does the qualifier "in place" mean here? Does that mean without
> using additional memory?[/color]

What does the qualifier "in place" mean here?
?hat does the qualifier "in place" mean hereW
?eat does the qualifier "in place" mean herhW
?ert does the qualifier "in place" mean heahW
?ere does the qualifier "in place" mean teahW
?ere does the qualifier "in place" mean teahW
?ere noes the qualifier "in place" mead teahW
?ere naes the qualifier "in place" meod teahW
?ere naes the qualifier "in place" meod teahW
?ere naem the qualifier "in place" seod teahW
?ere naem the qualifier "in place" seod teahW
?ere naem "he qualifier "in placet seod teahW

[Skarmander]

Re: Reverse a string "in place"

Richard Heathfield wrote:[color=blue]
> Water Cooler v2 said:
>
>[color=green]
>>I've asked myself this question in the past but couldn't afford more
>>time to it (I program other languages for my bread and butter), so I'll
>>ask now since it's never too late.
>>
>>What does the qualifier "in place" mean here? Does that mean without
>>using additional memory?[/color]
>
>
> What does the qualifier "in place" mean here?
> ?hat does the qualifier "in place" mean hereW
> ?eat does the qualifier "in place" mean herhW
> ?ert does the qualifier "in place" mean heahW
> ?ere does the qualifier "in place" mean teahW
> ?ere does the qualifier "in place" mean teahW
> ?ere noes the qualifier "in place" mead teahW
> ?ere naes the qualifier "in place" meod teahW
> ?ere naes the qualifier "in place" meod teahW
> ?ere naem the qualifier "in place" seod teahW
> ?ere naem the qualifier "in place" seod teahW
> ?ere naem "he qualifier "in placet seod teahW
> .
> .
> .
>
> I hope you can see how this is going.
>[/color]
Badly. Whaet? :-)

S.

[Richard Heathfield]

Re: Reverse a string "in place"

Skarmander said:
[color=blue]
> Richard Heathfield wrote:[color=green]
>> ?ere naem "he qualifier "in placet seod teahW
>> .
>> .
>> .
>>
>> I hope you can see how this is going.
>>[/color]
> Badly. Whaet? :-)[/color]

I *knew* I should have written code to do that. (sigh)

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

[Water Cooler v2]

Re: Reverse a string "in place"

Cool! Thanks a bunch, Richard.

[Richard Bos]

Re: Reverse a string "in place"

Richard Heathfield <invalid@invali d.invalid> wrote:
[color=blue]
> Skarmander said:
>[color=green]
> > Richard Heathfield wrote:[color=darkred]
> >> ?ere naem "he qualifier "in placet seod teahW
> >> .
> >> .
> >> .
> >>
> >> I hope you can see how this is going.
> >>[/color]
> > Badly. Whaet? :-)[/color]
>
> I *knew* I should have written code to do that. (sigh)[/color]

Yeah, every Anglo-Saxon fule noes that that should be "Hwaet!".

Richard

[Chuck F.]

Re: Reverse a string &quot;in place&quot;

Water Cooler v2 wrote:[color=blue]
>
> I've asked myself this question in the past but couldn't afford
> more time to it (I program other languages for my bread and
> butter), so I'll ask now since it's never too late.
>
> What does the qualifier "in place" mean here? Does that mean
> without using additional memory?[/color]

Almost. It means returning the result in the same storage in which
it arrived. This doesn't prevent using temporary auxiliary memory.

--
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[gooch]

Re: Reverse a string &quot;in place&quot;


Chuck F. wrote:[color=blue]
> Water Cooler v2 wrote:[color=green]
> >
> > I've asked myself this question in the past but couldn't afford
> > more time to it (I program other languages for my bread and
> > butter), so I'll ask now since it's never too late.
> >
> > What does the qualifier "in place" mean here? Does that mean
> > without using additional memory?[/color]
>
> Almost. It means returning the result in the same storage in which
> it arrived. This doesn't prevent using temporary auxiliary memory.[/color]

Is there even a way you could do it without temporary memory? I can't
think of one.

[Jordan Abel]

Re: Reverse a string &quot;in place&quot;

On 2005-12-23, gooch <gooch001@comca st.net> wrote:[color=blue]
>
> Chuck F. wrote:[color=green]
>> Water Cooler v2 wrote:[color=darkred]
>> >
>> > I've asked myself this question in the past but couldn't afford
>> > more time to it (I program other languages for my bread and
>> > butter), so I'll ask now since it's never too late.
>> >
>> > What does the qualifier "in place" mean here? Does that mean
>> > without using additional memory?[/color]
>>
>> Almost. It means returning the result in the same storage in which
>> it arrived. This doesn't prevent using temporary auxiliary memory.[/color]
>
> Is there even a way you could do it without temporary memory? I can't
> think of one.[/color]

You could use the xor trick.

[Alex Fraser]

Re: Reverse a string &quot;in place&quot;

"Chuck F. " <cbfalconer@yah oo.com> wrote in message
news:pY-dnTJJK5twWDbenZ 2dnUVZ_tudnZ2d@ maineline.net.. .[color=blue]
> Water Cooler v2 wrote:[color=green]
> > I've asked myself this question in the past but couldn't afford
> > more time to it (I program other languages for my bread and
> > butter), so I'll ask now since it's never too late.
> >
> > What does the qualifier "in place" mean here? Does that mean
> > without using additional memory?[/color]
>
> Almost. It means returning the result in the same storage in which
> it arrived. This doesn't prevent using temporary auxiliary memory.[/color]

But "in place" is usually taken to mean "with *constant* additional memory",
ie the amount of "temporary auxialliary memory" cannot depend on the length
of the string.

Alex

[Chuck F.]

Re: Reverse a string &quot;in place&quot;

gooch wrote:[color=blue]
> Chuck F. wrote:[color=green]
>> Water Cooler v2 wrote:[color=darkred]
>>>
>>> I've asked myself this question in the past but couldn't
>>> afford more time to it (I program other languages for my
>>> bread and butter), so I'll ask now since it's never too
>>> late.
>>>
>>> What does the qualifier "in place" mean here? Does that mean
>>> without using additional memory?[/color]
>>
>> Almost. It means returning the result in the same storage in
>> which it arrived. This doesn't prevent using temporary
>> auxiliary memory.[/color]
>
> Is there even a way you could do it without temporary memory? I
> can't think of one.[/color]

Yes. It depends on the fact that a C string cannot contain '\0'.
It is not recommended. The implementation is left as an exercise.

(BTW, this does not eliminate the need for counters, etc.)

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