How do I write this in pointer notation?

[Angela]

//array notation works********** *
char temp[]

for(int x=0; x<strlen(temp) ; x++)
{ temp[x]=(temp[x]*2); } //simple char encoding

//how do I do the same thing with pointer notation******* ***
char* temp

while( *temp )
{ *temp++= (*temp)*2; } //simple char encoding

I have played around with this and usually it just erases the first
few letters. If I wanted to do something like this with a C++ string,
is this possible?

[lilburne]

Re: How do I write this in pointer notation?

Angela wrote:
[color=blue]
> //array notation works********** *
> char temp[]
>
> for(int x=0; x<strlen(temp) ; x++)
> { temp[x]=(temp[x]*2); } //simple char encoding
>
> //how do I do the same thing with pointer notation******* ***
> char* temp
>
> while( *temp )
> { *temp++= (*temp)*2; } //simple char encoding
>
> I have played around with this and usually it just erases the first
> few letters. If I wanted to do something like this with a C++ string,
> is this possible?[/color]


{ *temp++= (*temp)*2; } //simple char encoding

The *temp++ has the side effect of incrementing temp, so the
temp on the left is not the same as the temp on the right.

*temp++ *= 2;

[Artie Gold]

Re: How do I write this in pointer notation?

Angela wrote:[color=blue]
> //array notation works********** *
> char temp[]
>
> for(int x=0; x<strlen(temp) ; x++)
> { temp[x]=(temp[x]*2); } //simple char encoding
>
> //how do I do the same thing with pointer notation******* ***
> char* temp
>
> while( *temp )
> { *temp++= (*temp)*2; } //simple char encoding[/color]

You cannot do it this way; the value of `temp' is being altered
without an intervening sequence point causing undefined behavior.

One correct option would be to mimic the array form, as in:

for (; *temp; temp++)
*temp = *temp * 2;
[color=blue]
>
> I have played around with this and usually it just erases the first
> few letters.[/color]

Yes, due to the invocation of undefined behavior noted above.
[color=blue]
> If I wanted to do something like this with a C++ string,
> is this possible?[/color]

Yes. Certainly. (Look up `iterator' and `transform', for example)

HTH,
--ag

--
Artie Gold -- Austin, Texas
Oh, for the good old days of regular old SPAM.

[Artie Gold]

Re: How do I write this in pointer notation?

lilburne wrote:

[snip][color=blue]
>
>
> { *temp++= (*temp)*2; } //simple char encoding
>
> The *temp++ has the side effect of incrementing temp, so the temp on the
> left is not the same as the temp on the right.
>
> *temp++ *= 2;[/color]

Better than my original reply! (on this point)
[color=blue]
>
>[/color]
--ag


--
Artie Gold -- Austin, Texas
Oh, for the good old days of regular old SPAM.