Modules - Global Data

Fortran 90 implements a new mechanism to implement global data:

• declare the required objects within a module;
• give them the SAVE attribute;
• USE the module when global data is needed.

For example, to declare pi as a global constant

  MODULE  Pye
   REAL, SAVE :: pi = 3.142
  END MODULE Pye

  PROGRAM Area
   USE Pye
   IMPLICIT NONE
   REAL :: r
    READ*, r
    PRINT*, "Area= ",pi*r*r
  END PROGRAM Area

MODULE s should be placed before the program.

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