Using external functions
External functions are functions that are written in languages
other than PowerScript and stored in dynamic libraries. External functions are stored in
dynamic link libraries (DLLs).
You can use external functions written in any language that
supports the standard calling sequence for 32-bit platforms.
If you are calling functions in libraries that you have written
yourself, remember that you need to export the functions. Depending
on your compiler, you can do this in the function prototype or in
a linker definition (DEF) file.
Use _stdcall convention
C and C++ compilers typically support several
calling conventions, including _cdecl (the
default calling convention for C programs), _stdcall (the
standard convention for Windows API calls), _fastcall,
and thiscall. PowerBuilder, like many other Windows
development tools, requires external functions to be exported using
the WINAPI (_stdcall) format. Attempting
to use a different calling convention can cause an application crash.
When you create your own C or C++ DLLs containing
functions to be used in PowerBuilder, make sure that they use the
standard convention for Windows API calls. For example, if you are
using a DEF file to export function definitions, you can declare
the function like this:
|
1 |
LONG WINAPI myFunc()<br>{<br>...<br>}; |
Using PBNI
You can also call external functions in PowerBuilder extensions.
PowerBuilder extensions are built using the PowerBuilder Native
Interface (PBNI). For more information about building PowerBuilder
extensions, see the PowerBuilder Native Interface Programmers
Guide and Reference. For more information about using
PowerBuilder extensions, see the PowerBuilder Extension Reference.