Q: how to convert a String to PChar?
Arjan
Hi,
Can anyone tell me how I convert a string to PChar?
I need the PChar to call the function CopyFile.
C-ya!
Arjan
Alexander Apostolovski
> Can anyone tell me how I convert a string to PChar?
> I need the PChar to call the function CopyFile.
StrPCopy or StrCopy (I always mix these two)
Alexander
------------------------------
Luis Mourao
avd...@worldaccess.nl (Arjan) wrote:
>Hi,
>Can anyone tell me how I convert a string to PChar?
>I need the PChar to call the function CopyFile.
>C-ya!
> Arjan
Hi Arjan,
Like Alexander says..., StrPCopy. Here's an example:
uses SysUtils;
var
A: array[0..79] of Char;
S: String;
begin
S := 'Honk if you know Blaise.';
StrPCopy(A, S);
Canvas.TextOut(10, 10, StrPas(A));
end;
I hope this helps,
--
Luis Mourao
http://www.intelitech.com
in...@intelitech.com
Ray Lischner
On Thu, 23 Jan 1997 09:09:03 GMT, avd...@worldaccess.nl (Arjan)
wrote:
>Can anyone tell me how I convert a string to PChar?
>I need the PChar to call the function CopyFile.
D2 handles this for you. Just cast the string to PChar. In D1, it's
harder because you have no guarantee that the string has a zero byte
at its end, so you might need to make a copy of the string.
Secrets of Delphi 2 has a StrToPChar function that takes care of these
details for you. In D2, it simply uses a type cast, PChar(str). In D1,
it checks to see if the string already has a zero byte at its end, in
which case, it returns a pointer to the first character in the string.
Otherwise, it dynamically allocates a character array and copies the
Pascal string. It remembers several old strings, and automatically
frees the strings after a certain number of allocations. This achieves
a nice balance between having too many strings lying around, wasting
memory, and being able to use several PChar strings simultaneously in
a Windows API call.
--
Ray Lischner, Tempest Software, Inc., Corvallis, Oregon, USA
Author of Secrets of Delphi 2 (http://www.tempest-sw.com/secrets/)
Ray Lischner
>> Can anyone tell me how I convert a string to PChar?
>> I need the PChar to call the function CopyFile.
>
>StrPCopy or StrCopy (I always mix these two)
As a general rule, I prefer StrPLCopy to StrPCopy. If the source
string is longer than the destination character array, StrPLCopy does
not run off the end of the array. StrPCopy overwrites memory and
causes your program to misbehave.
Jason Wallace
Arjan wrote:
>
> Hi,
> Can anyone tell me how I convert a string to PChar?
> I need the PChar to call the function CopyFile.
It's really easy. Use 'Pchar(myString)' instead of using just
'myString' in the function...
--
Jason
E...@DarkElf.reno.nv.us
Mark Bracey
Arjan wrote:
>
> Hi,
>
> Can anyone tell me how I convert a string to PChar?
>
> I need the PChar to call the function CopyFile.
>
>
> Arjan
If you have Dog which is a String;
then Dog := Dog + #0;
Addr(Dog[1]) is a Pchar
CopyFile(Addr(Dog[1]));
Ralf Steinhaeusser
In article <32efa451...@news.proaxis.com>, li...@tempest-sw.com wrote:
>>> Can anyone tell me how I convert a string to PChar?
>>> I need the PChar to call the function CopyFile.
It might be crap but I think I somewhen read something about
converting Stings using PChar(s).
As I said - It might be $ง&!X#1&ง.
bye, ralf.
Andrew Hollands
Arjan wrote:
> Can anyone tell me how I convert a string to PChar?
StrPCopy(PCharString, AnsiString);
--
-------------------------------------------------------
"I never gave anybody Hell. I just told them the truth
and they thought it was Hell..." -Harry S. Truman
Mark Bracey
Jason Wallace wrote:
>
> Arjan wrote:
> >
> > Hi,
> > Can anyone tell me how I convert a string to PChar?
>
> 'myString' in the function...
>
> --
> Jason
> E...@DarkElf.reno.nv.us
This won't work for AnsiString because it is implemented like an Object.
Antonio Linares
> >> Can anyone tell me how I convert a string to PChar?
This works for me:
@str[ 1 ]
regards,
Jesper Frank Nemholt
This works for me :
My_PChar := PChar('name_of_string');
l8r/Jspr
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------------------
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Svante Granqvist
Jesper Frank Nemholt wrote:
>
> Antonio Linares wrote:
> >
> > > >> Can anyone tell me how I convert a string to PChar?
> >
> > This works for me:
> >
> > @str[ 1 ]
> >
> > regards,
>
> This works for me :
>
> My_PChar := PChar('name_of_string');
>
@str[1] works if there is a #0 at the end, which you might have to put
there manually if it is a shortstring.
PChar(str) does not work for a shortstring.
The preferable way must be strpcopy or strplcopy since there is
compatibility between ansistring and shortstring.
--
Svante Granqvist Speech, Music and Hearing
Phone +46-8-790 7561 Box 700 14
Fax +46-8-790 7854 S-100 44 Stockholm
mailto:sva...@speech.kth.se http://www.speech.kth.se/~svante
Andre L. Bazan
Ray Lischner <li...@tempest-sw.com> wrote in article
<32efa451...@news.proaxis.com>...
> On Thu, 23 Jan 1997 11:24:51 +0100, Alexander Apostolovski
> <apos...@cs.utwente.nl> wrote:
>
> >> Can anyone tell me how I convert a string to PChar?
> >> I need the PChar to call the function CopyFile.
> >
> >StrPCopy or StrCopy (I always mix these two)
>
> As a general rule, I prefer StrPLCopy to StrPCopy. If the source
> string is longer than the destination character array, StrPLCopy does
> not run off the end of the array. StrPCopy overwrites memory and
> causes your program to misbehave.
>
> --
> Ray Lischner, Tempest Software, Inc., Corvallis, Oregon, USA
> Author of Secrets of Delphi 2 (http://www.tempest-sw.com/secrets/)
>
It seems as if Ray Hit the Nail on the Head...
The simplest way to convert a string to a PChar is to typecast it as a
PChar in the following manner (a very simple example but the method works
with everything from simple text assignment to the Windows API):
procedure TForm1.Button1Click(Sender: TObject);
var
MyString: String;
begin
// Typecast the AnsiString as a PChar like this --> PChar(MyString) as
shown // below
MessageBox(Handle, PChar(MyString), nil, mb_OK);
end;
Good Luck,
Andre
Michael Lee
Maybe I'm missing something, but if Borland created a specialised
StrPCopy operation, then doesn't it seem like a good idea to use it.
Its like incrementing values; just as easy to do I := I + 1 as Inc(I),
but you'd have to assume that the compiler generates better code (ie
uses the inc assembler command) using the Delphi preferred method.
Why the hell else would they have a StrPCopy operation?
Michael.
Delphi Developer's Jrnl
Mark Bracey wrote:
> Jason Wallace wrote:
> > It's really easy. Use 'Pchar(myString)' instead of using just
> > 'myString' in the function...
In fact, it will work, but only with Delphi 2.0. If you modify the PChar
while in the function, you need to perform a redundant cast:
myString := PChar(WhateverThePCharNameIs);
This will reset the length info in the AnsiString.
If you don't believe me, place a Button and three (3) Label components
on a form. Double-click the button and add the following:
procedure TForm1.Button1Click(Sender: TObject);
var
name : AnsiString;
TempName :PChar;
begin
name := 'Dummy Text';
Label3.Caption := IntToSTr(Length(name)) + ' ' + name;
TempName := PChar(name);
GetWindowText(Handle, TempName, Length(name));
Label1.Caption := IntToStr(Length(name)) + ' ' + name;
name := PChar(TempName);
Label2.Caption := IntToStr(Length(name)) + ' ' + name;
end;
Run, click the Button, and see the lengths and the captions.
Hope this helps,
--
Tim Gooch
Editor-in-Chief, Moderator,
Delphi Developer's Journal DDJ-THREAD - Delphi Discussion List
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Svante Granqvist
Michael Lee wrote:
>
> Maybe I'm missing something, but if Borland created a specialised
> StrPCopy operation, then doesn't it seem like a good idea to use it.
>
>
Because strpcopy is needed for the old (delphi 1 & BP7) type of strings
which are known as shortstring in delphi 2. Strpcopy was introduced
to convert (old style) strings to the C-ish windows environment, long
before huge strings were invented.
pchar(ansistring) works fine, though, and I'd guess that it is the
most efficient for ansistrings (but not sure, the compiler IS smart)
David Ullrich
Michael Lee wrote:
>
> Maybe I'm missing something, but if Borland created a specialised
> StrPCopy operation, then doesn't it seem like a good idea to use it.
>
> but you'd have to assume that the compiler generates better code (ie
> uses the inc assembler command) using the Delphi preferred method.
It depends on what you're doing. StrPCopy makes a copy of the
string, while simply typecasting the string to a PChar doesn't copy
anything, it just gives a pointer to the first character. If you're
going to be modifying the contents of the string probably it should
be StrPCopy - the new strings are smart enough to get very confused
if you start manipulating them other than via Delphi string functions.
Otoh if, say, you have a string and you just want to pass it to an
API function (a function which will not change the "string") then
I don't see what's wrong with the typecast (unless compatibility
with D1 is an issue).
--
David Ullrich
?his ?s ?avid ?llrich's ?ig ?ile
(Someone undeleted it for me...)
Ulrich Kroener
On 24 Jan 1997 08:50:43 GMT, "Willo van der Merwe"
<wil...@infoview.co.za> wrote:
>> I need the PChar to call the function CopyFile.
>In Delphi 2.0 you can just typecast:
> P := pChar( S );
In Delphi 1 and 2 you can use:
StrPCopy(PCharPath, Path);
-- Ulrich Kroener