Write a function called popStack in the programming language C,
which performs the popping operation of a stack. The stack is
represented by a one dimensional integer array of 100 elements called
stack, which must be passed to the function as a parameter. An integer
value called number, which identifies (the top number of elements) in
the stack must also be passed to the function as a parameter. In
popping the stack, the function should replace the emptied array
location with the value of “-99-” and return the value which was
popped.
