Scope of Variables

The scope of an entity is the part of the program where the entity is visible. The main program, a function or a procedure are scoping units; an entity declared inside a scoping unit is visible throughout the unit.

In particular, a variable declared in the main program or in a procedure has the body of the program/pocedure as its scope.

A variable is local (has local scope) if its scope is that of a scoping unit.

A variable whose scope is the entire program has global scope.

Some variables can be seen by multiple program units - by extension we will also talk about global scope. Global storage (global scope variables) can be implemented using modules or common blocks. This is discussed later in this chapter.