Open Watcom FORTRAN 77 Language Reference

Language Reference
If there is a LOCATION= specifier, the expression in the specification is evaluated and that value is used as
the address of the array or character variable. This permits the programmer to specify a substitute memory
allocator or to map the array or character variable onto a fixed memory location.
Example:
DIMENSION A(:), B(:,:)
.
.
.
ALLOCATE( A(N) )
ALLOCATE( B(0:4,5) )
More than one allocatable array or character variable may appear in an ALLOCATE statement, separated by
commas.
Example:
DIMENSION A(:), B(:,:)
.
.
.
ALLOCATE( A(N), B(0:4,5) )
If the allocation fails and the STAT= specifier was not used, an execution-time error occurs. If the STAT=
specifier is used, the specified variable returns a zero value if the allocation succeeded, and a non-zero
value if the allocation failed.
Example:
DIMENSION A(:), B(:,:)
.
.
.
ALLOCATE( A(N), B(0:4,5), STAT=IALLOC )
IF( IALLOC .NE. 0 ) PRINT *, ’Allocation failure’
An attempt to allocate a previously allocated array or character variable results in an execution-time error.
If the LOCATION= specifier was not used, the array or character variable must be deallocated first before it
can be allocated a second time (see the DEALLOCATE statement).
An absolute memory location may be specified using the LOCATION= specifier.
Example:
CHARACTER*1 SCREEN(:,:)
N = 80*25
*$IFDEF __386__
ALLOCATE( SCREEN(0:1,0:N-1), LOCATION=’B8000’x )
*$ELSE
ALLOCATE( SCREEN(0:1,0:N-1), LOCATION=’B8000000’x )
*$ENDIF
DO I = 0, N-1
SCREEN(0,I) = ’*’
ENDDO
END
The above example maps the array SCREEN onto the IBM PC colour monitor screen memory and then fills
the screen with asterisks (16-bit real-mode only). The character is stored in SCREEN(0,I) and the
14 ALLOCATE Statement