STRPTR functionality wish

[Aldo Cavini]

Is it possible to make STRPTR work on string equates? Something like:

$a = "Aldo Cavini"
b  = STRPTR( $a )

This could be useful, for instance, on registering a Window Class. The only way I know to assign the lpszClassName value is via a string or asciiz variable. Am I wrong?

Aldo

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[Edwin Knoppert]

I think not but:

Control Add "" & $HELLO works fine..

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http://www.hellobasic.com

[Lance Edmonds]

It is not possible to obtain a VARPTR or a STRPTR to a String Equate. Think of them as mini-macro's - they are "used" during compile-time, not run-time.

However, depending on how the API you are calling is declared, you may be able to pass the string equate BYCOPY (which is what Edwin's example above is doing).

' These all pass bycopy:
CALL apifunction(BYCOPY $MyString) ' Explicit BYCOPY
CALL apifunction($MyString + "")   ' Expressions passed BYCOPY
CALL apifunction(($MyString))      ' Parentheses force evaluation as an expression, hence BYCOPY

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Aldo Cavini]

Edwin, Lance,

thanks for the replies. Of course I do know how to pass a string by value. What I would like do is the following:

LOCAL wc as WndClassEx 
  ...
  wc.lpszClassName = VARPTR( AsciizVariable )
  ...
  RegisterClassEx wc

or

  wc.lpszClassName = STRPTR( StringVariable )

without having to use a variable. I mean:

  wc.lpszClassName = VARPTR( $StringEquate )

I thought, since the string equate value is stored somewhere inside the executable file, its address could be retreived at run-time. Never mind...


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[Aldo Cavini]

posted http://www.powerbasic.com/support/pb...ad.php?t=23155

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[Lance Edmonds]

Cute... using a function means you can pass string equates BYCOPY/BYVAL and register your window.

I'm sure there are plenty of places this approach could be used, except when you want the code in line.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Peter P Stephensen]

Hi Aldo,

I use the following inc-file:

#if not %def(%TEXT_INC)
%TEXT_INC = 1
 
%TEXT = 1
%FreeTEXT = 2
 
global TEXTMemory() as string   ' Would be better as static inside MainTEXTfunc. Not safe in current version of PB.
function MainTEXTfunc(byval func_id as long, byval s as string) as dword
 
    static n as long
     
    select case func_id
    case %TEXT
        redim preserve TEXTMemory(n)
        TEXTMemory(n) = s
        incr n
        function = strptr(TEXTMemory(n-1)) : exit function
 
    case %FreeTEXT
        n = 0
        redim TEXTMemory(0)
     
    end select
 
end function
 
function TEXT(byval s as string) as dword
    function = MainTEXTfunc(%TEXT, s)
end function
 
sub FreeTEXT()
    MainTEXTfunc %FreeTEXT, ""
end sub
 
#endif '%TEXT_INC

If you use this as header-file, you can use any of the following
alternatives:

    wc.lpszClassName = TEXT( AsciizVariable )
    wc.lpszClassName = TEXT( StringVariable )
    wc.lpszClassName = TEXT( $StringEquate )
    wc.lpszClassName = TEXT( "MyClassName" )

Regards
Peter

P.S.

If you like you can free memory using FreeTEXT (you dont have to)

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[email protected]

[Aldo Cavini]

Peter,

good idea. I also had the idea to assign the string equate to a static/global string, but didn't thought about using an array

Aldo

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