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─────INCLUDE────────────────────────────────────────────────────────────────
 
     Action
 
     Inserts the contents of a specified text file at the location of
     the INCLUDE statement.
 
     Syntax
 
     INCLUDE 'filename'
 
     Parameter          Description
 
     filename           The name of the text file to include, surrounded
                        by apostrophes.
 
     Remarks
 
     The <filename> must be a valid text file specification.
 
     The compiler considers the contents of the include file to be
     part of the program file.
 
     Include files are primarily used for data or program units that
     appear in more than one program.
 
     FORTRAN allows nesting of up to 10 include files. The operating
     system may impose further restrictions.
 
     See Also: ◄/I►
               ◄$INCLUDE►
 
     Example
 
     C     This program implements a stack by declaring the common stack
     C     data in an include file. The contents of the file STKVARS.FOR
     C     (shown below in the following program) are inserted in the
     C     source code in place of every INCLUDE statement. This
     C     guarantees that all references to common storage for stack
     C     variables are consistent.
 
           INTEGER i
           REAL    x
           INCLUDE 'stkvars.for'
 
     C     read in five real numbers:
           DO 100 i = 1, 5
              READ (*, '(F10.5)') x
              CALL Push (x)
       100 CONTINUE
 
     C     write out the numbers in reverse order:
           WRITE (*, *) ' '
           DO 200 i = 1, 5
              CALL Pop (x)
              WRITE (*, *) x
       200 CONTINUE
           END
 
           SUBROUTINE Push (x)
     C     Pushes an element x onto the top of the stack.
 
           REAL x
           INCLUDE 'stkvars.for'
 
           top = top + 1
           IF (top .GT. stacksize)  STOP 'Stack overflow'
           stack(top) = x
           END
 
           SUBROUTINE pop(x)
     C     Pops an element from the top of the stack into x.
 
           REAL x
           INCLUDE 'stkvars.for'
 
           IF (top .LE. 0)  STOP 'Stack underflow'
              x   = stack(top)
              top = top - 1
           END
 
     The following is the text file STKVARS.FOR:
 
     C     This file contains the declaration of the common block
     C     for a stack implementation. Because this file contains an
     C     assignment statement, it must be included only after all
     C     other specification statements in each program unit.
 
           REAL     stack(500)
           INTEGER  top, stacksize
 
           COMMON  /stackbl/ stack, top
 
           stacksize = 500
                                    -♦-