Open Watcom FORTRAN 77 Language Reference

Language Reference
2.80 UNION Statement
UNION
The UNION statement is used in conjunction with the END UNION declarative statement. The UNION
statement marks the start of a series of MAP structures. A UNION block must contain at least two MAP
structures. A UNION block permits the mapping of the same storage in several different ways.
The following example maps out a 4-byte integer on an Intel 80x86-based processor.
Example:
STRUCTURE /MAPINT/
UNION
MAP
INTEGER*4 LONG
END MAP
MAP
INTEGER*2 LO_WORD
INTEGER*2 HI_WORD
END MAP
MAP
INTEGER*1 BYTE_0
INTEGER*1 BYTE_1
INTEGER*1 BYTE_2
INTEGER*1 BYTE_3
END MAP
END UNION
END STRUCTURE
RECORD /MAPINT/ I
I%LONG = ’01020304’x
PRINT ’(2Z4)’, I%LO_WORD, I%HI_WORD
END
For more information, see the chapter entitled "Structures, Unions and Records" on page 167.
142 UNION Statement