about XLL memory management

Hi guys, I have problem to deal with XLL memory management. Firstly, have a look at the following code please. (plainxll.cpp). This XLL registered 2 UDFs: test and testd. Both return an LPXLOPER12 ...

excel

yushang

Brass Contributor

Mar 29, 2023

Rodrigo_ Thanks for reply. I would like to summarize the usage of xlbitDLLFree as follow

1. xlbitDLLFree is used only in scenario when UDF return a dynamic allocated XLOPER12

2. For the returned XLOPER12, if xlbitDLLFree is set, Excel will pass it back to xlAutoFree12. if not set there will be a memory leak.

there leaves a question, what will happen if XLL did not export xlAutoFree12?

In parallel, can I summarize the usage of xlbitXLFree as follow?

1. xlbitXLFree is used only in scenario when UDF return a dynamic allocated XLOPER12

2. For the returned XLOPER12, if xlbitXLFree is set, Excel will free it including the XLOPER12 itself (I'm especially caring about this, from the official https://learn.microsoft.com/en-us/office/client-developer/excel/memory-management-in-excel#example, it seems there is little chance I'm right), if not set, there will be a memory leak.

(all the dynamic allocated XLOPER12 mentioned above does not contain static allocated memory, for example, val.str is not static allocated).