Has anyone encountered a null pointer assertion when adding a subitem to cmfcpropertygridproperty

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Complicated C++ code, but the essence in pseudocode is:
I have a pGroup1 = CMFCPropertyGridProperty * with the following structure.
pGroup1
subGroup1ItemA("Numeric")
subGroup1ItemA_1("PI",(_variant_t) "3.14", "ratio" )
subGroup1ItemA_2("e",(_variant_t) "2.7182", "growth" )
subGroup1B("Text")
subGroup1C("Point")

This is established at runtime, works fine.
However, when I add, during subsequent user interaction:
subGroup1ItemA("Numeric").addSubItem("Phi",(_variant_t) "1.618", "gold" )
The program encounters a NULL pointer assertion in the DLL(mfc140ud.dll) when the mouse flies over the window containing these CMFCPropertyGridProperty objects.

What I have tried:

Swearing, hair-pulling.
Also, caught the exception but still have no idea which object's pointer in null.
Stepping through the code that adds this item works, and I can verify the added object is in the correct position of the altered node-header chain.

Posted 2-Nov-20 6:04am

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Updated 2-Nov-20 8:08am

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Shao Voon Wong 2-Nov-20 18:45pm

Can you upload to GitHub, a sample project that reproduces the problem? Because I cannot find an addSubItem method that matches your arguments. You are not supposed to cast string literal to _variant_t: those are 2 different types.

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KarstenK · Answer 1 · 2020-11-02T08:09:00

Solution 1

The NULL pointer assertion is the result, that you missed something. It sounds like you activated tooltips in some manner but dont provide them correctly. I would override the tooltip function to have full control about it or deactivate them.

Give that answer a shot.

Posted 2-Nov-20 8:09am

KarstenK