how to make a matlab structure into a pointer

I have a structure that I need to pass as a c type pointer to a library function, but when following the example from this help page https://uk.mathworks.com/help/matlab/ref/libstruct.html it comes up with an error Undefined function or variable 'lib.c_struct'.

So how would I go about creating the pointer I need?

This is the code I've been trying;

if ~libisloaded('shrlibsample')

addpath(fullfile(matlabroot,'extern','examples','shrlib'))

loadlibrary('shrlibsample')

end

sm.p1 = 0;

sm.p2 = 0;

sm.p3 = 0;

sm.p4 = 0;

sm.p5 = 0;

sm.p6 = 0;

sm.p7 = 0;

sc = libstruct('c_struct')