GetModuleHandle (BYVAL 0) vs. GetModuleHandle($NUL)

[Semen Matusovski]

Ralph --
I searched in POFFS2
No one GetModuleHandle($NUL) found.
BTW, it seems to me that I never used $NUL at all, not in GetModuleHandle only (%NULL - yes)



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[Ralph Berger]

Semen,

as i remember i found GetModuleHandle($NUL) in
your src postings too.

Ralph

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[Ralph Berger]

Thanks for the help. I'll use GetModuleHandle(BYVAL 0)
to get the current instance.
Just to be shure : Literals are STRPTR. Aren't they ?

rgds
Ralph



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[Semen Matusovski]

I think that $NUL = CHR$(0) instead of $NUL = "" and PB operates with it like with string with length = 1.
For example, Len("a" + $NUL + "a") = 3.

Imagine

Sub ab (s As Asciiz)

If to call ab "", PB will transfer 0& as address of s. That's why GetModuleHandle("") will work.

But in case

Dim a As Asciiz * 100
ab a

PB transfers a pointer to a byte with value 0.
It's not the same

PS. I saw Lance answer too late.

[This message has been edited by Semen Matusovski (edited May 20, 2001).]

[Lance Edmonds]

$NUL is a built-in string equate, %NULL is a user-defined equate (it is defined in WIN32API.INC for convenience).

To be clear, using $NUL is the same as using CHR$(0). That is, it specifies a 1 byte string containing one CHR$(0).

Therefore, your API call code could be rewritten to show the problem more clearly:

CALL GetModuleHandle(CHR$(0))

...which is clearly wrong. As Steve says, you need to pass the value zero to the API. If you tried BYCOPY $NUL, you'd be sending the address of a zero byte, which would be wrong for the API context.

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

[Steve Hutchesson]

Ralph,

%NULL should be a numeric value where your equate is a string
equate.

I usually use ByVal %NULL as the parameter.

Regards,

[email protected]

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[Ralph Berger]

Hi there,

this works fine :
hICONInfo = LoadIcon( GetModuleHandle(BYVAL 0), BYVAL MAKLNG(1003,0) )

but when i use $NUL hIconInfo is 0 :
hICONInfo = LoadIcon( GetModuleHandle($NUL), BYVAL MAKLNG(1003,0) )

What is $NUL ? A STRPTR, a VARPTR or simply 0 ?

Ralph

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