Define static, stack-dynamic, explicit heap-dynamic, and implicit heap-dynamic variables. What are their advantages and disadvantages?
= Static: bound to memory cells before execution begins and remains bound to the same memory cell throughout the execution.
Stack-dynamic: storage bindings are created for variables when their declaration statements are elaborated.
Explicit heap-dynamic: allocated and deallocated by explicit directives, specified by the programmer, which take effect during execution.
Implicit heap-dynamic variables: Allocation and deallocation caused by assignment statements.