C function returning an mxArray pointer

Hello!

I am trying to interface our software to Matlab using the functionality to call external, shared libraries from Matlab using loadlibrary and calllib.

My question is:

If I have a C function returning a mxArray pointer: mxArray* myCFunction(mxArray* args);

Will then Matlab be responsible for deleting the object? What If the function returns a null pointer or the input arguments, is this forbidden, e.g.: mxArray* myCFunction(mxArray* args){ return args; }

or

mxArray* myCFunction(mxArray* args){ return 0; }

Best, Joel

Answer 1

[Philip Borghesani]

The rules are the same as for outputs returned via plhs in a mex file.

In short:

• To return an input a copy must be made with mxDuplicateArray.
• MATLAB will delete the object when there are no longer any references to it in MATLAB.
• A null pointer should convert to an empty double array but test this if you depend on it.

[Joel Andersson]

Alright. Thank you for clarifying!