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FutureBasic 5 |
begin union | statement | |
|
begin record
recordName
dim
statements
...
begin union
dim
statements
end union
dim
statements
...
end record
begin record RecordWithUnion
dim as long beforeUnion
begin union
dim as UInt8 inUnion1
dim as Str255 inUnion2
end union
end record
dim as RecordWithUnion myTest
myTest.inUnion2 = "COW"
print myTest.inUnion1
The variable myTest.inUnion1
is a single byte which occupies the same space as the first byte in the string myTest.inUnion2
. In this case, myTest.inUnion1
happens to be the length byte of the string and the print
statement will produce "3". Such an overlap is not necessary and the two values may have no relation to one another except that they start at the same location in memory.
When FutureBasic encounters a begin union
statement, all dim
statements up to the end union
statement are examined and the largest item in the union determines the amount of space set aside by the compiler. In the example above, the union would occupy 256 bytes since the largest element in the union is a 256 byte Pascal string.
See Also:
dim; begin record