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Some help with a dylib, please
Posted: Tue Jun 12, 2018 12:38 pm
by simberr
I have been successful in creating a dylib which takes input parameters and exports numeric data (all types well).
However, I am having great difficulties in exporting (Returning from procedure) a string.
A code snippet is as follows:
Code: Select all
Global ReturnString.s
ProcedureDLL.s GetString() ;Create unicode executable gives only first character
ReturnString = "More then H"
ProcedureReturn ReturnString
EndProcedure
This compiles correctly into a dylib.
The declaration in my source code (Xojo) is:
Code: Select all
Declare Function GetString Lib libname As CString
The returned value that I get from the procedure is just the first character - "M".
Can anybody help me?
Re: Some help with a dylib, please
Posted: Tue Jun 12, 2018 1:30 pm
by mk-soft
Purebasic v5.6x is Unicode
Code: Select all
Threaded ReturnString.s
ProcedureDLL.i GetString()
ReturnString = "More then H"
ProcedureReturn @ReturnString
EndProcedure
I don´t know this right "WString as Result
Declare Function GetString Lib libname As WString
Re: Some help with a dylib, please
Posted: Wed Jun 13, 2018 12:52 am
by simberr
Thank you, I will try that.
Re: Some help with a dylib, please
Posted: Wed Jun 13, 2018 9:22 am
by simberr
The code that you posted works inasmuch as I now get a string returned from my dylib.
Unfortunately, this string is a 4 byte string rather than a two byte string so I get every other byte as a zero. This, of course, is not readable when displayed as the string
"More then H"
is returned as
"M*o*r*e* *t*h*e*n* *H*" (asterisks are Chr(0)).
This is because MacOS sees a String as 4 bytes. I tried using CString in my declare but this did not work, only String works (as you suggested).
Any further advice?
Re: Some help with a dylib, please
Posted: Wed Jun 13, 2018 9:31 am
by mk-soft
I think go back to CString...
Edit
Code: Select all
;-TOP
CompilerIf #PB_Compiler_Version < 550
Procedure Ascii(string.s)
Protected *result
*result = AllocateMemory(Len(String) + 1)
If *result
PokeS(*result, String, -1, #PB_Ascii)
EndIf
ProcedureReturn *result
EndProcedure
Procedure UTF8(string.s)
Protected *result
*result = AllocateMemory(StringByteLength(String, #PB_UTF8) + 1)
If *result
PokeS(*result, String, -1, #PB_UTF8)
EndIf
ProcedureReturn *result
EndProcedure
CompilerEndIf
Threaded *ReturnString
ProcedureDLL.i GetString()
If *ReturnString
FreeMemory(*ReturnString)
EndIf
*ReturnString = Ascii("Hello World")
ProcedureReturn *ReturnString
EndProcedure
Re: Some help with a dylib, please
Posted: Wed Jun 13, 2018 3:17 pm
by simberr
Absolutely perfect.
Thank you so much, I have been agonising over this for four whole days.
You are a star.