Question

what is wrong with the following line of code:
v->size-1+v->myarray=&number;

Answer 1

Are you sure you want to store the address of number? Also, I think you need to derefernce that pointer.
*(v->size-1+v->myarray)=number;

Here's the more sensible way of writing that line:
v->myarray[v->size - 1] = number;
assuming you want to actually use the value of number.

Answer 2

Maybe you need to reverse it and say... &number = v->size blah blah blah