Help with my first DLL :)

[Neil Hosgood Member Find all posts View Profile Close Neil Hosgood]

Hi all.
After telling my employer that I refuse to learn Delphi I
now have to write a DLL in PB that he can use with Delphi.
Problem is that haven written many EXE's I have never written
a DLL, let alone called a PB DLL from Delphi.
Question is... most of the functions in my DLL require a string
to be passed, an asciiZ to be extact, so in my DLL do I set up
the parameters as Function ... (string1 as asciiZ * 255) as Long
OR Function ... (String1 as Long) as Long ?
You will have to excuse my ignorance, I am used to just throwing
dynamic strings around my own EXE in windows



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[Lance Edmonds Member Find all posts View Profile Close Lance Edmonds]

If you are passing the ASCIIZ string (byref) from Delphi, then it should be passing a pointer to the ASCIIZ string data, hence you would construct the function prototype something like this:

FUNCTION DllFunc ALIAS "DllFunc" (mystr AS ASCIIZ) EXPORT AS LONG

I have left off the "length" qualifier which is acceptable, provided you do not attempt to access memory beyond the length of the passed string. With the length qualifier, PowerBASIC will protect you from this to some degree, but only if the length of the passed ASCIIZ string is equal to or greater than the length specified in the PB code Function prototype. (Clear as mud? )

Also, you need to include the keyword EXPORT, or the function will not be "visible" to the Delphi app.

Finally, I added an ALIAS clause to specify the exported Function name specifically... exported Sub/Function names are case-sensitive in 32-bit Windows.


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

[Neil Hosgood Member Find all posts View Profile Close Neil Hosgood]

Thanx Lance, thats the answer I needed.
you're a god.

PS. on my journey through the PB6 help file on the topic of
creating a DLL I was disturbed to find it telling me to
start up the PB5 editor. (hmmm if I bought a new car would I
expect it to come with a manual for last years model?)
Just my little bleat for the day.
have Fun.
N.

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