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Methods for Accessing Nonlocals

• FORTRAN COMMON
  • The only way in pre-90 FORTRANs to access nonlocal variables
  • Can be used to share data or share storage

• Static scoping--discussed in Chapter 4

• External declarations: C
  • Subprograms are not nested
  • Globals are created by external declarations (they are simply defined outside any function)
  • Access is by either implicit or explicit declaration
  • Declarations (not definitions) give types to externally defined variables (and say they are defined elsewhere)

• External modules: Ada and Modula-2: Sec Ch. 10

• Dynamic Scope: discussed in Ch. 4