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(g77-300.info)Alternate Returns

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Alternate Returns (SUBROUTINE and RETURN)
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   Subroutines with alternate returns (e.g. `SUBROUTINE X(*)' and `CALL
X(*50)') are implemented by `g77' as functions returning the C `int'
type.  The actual alternate-return arguments are omitted from the
calling sequence.  Instead, the caller uses the return value to do a
rough equivalent of the Fortran computed-`GOTO' statement, as in `GOTO
(50), X()' in the example above (where `X' is quietly declared as an
`INTEGER(KIND=1)' function), and the callee just returns whatever
integer is specified in the `RETURN' statement for the subroutine For
example, `RETURN 1' is implemented as `X = 1' followed by `RETURN' in
C, and `RETURN' by itself is `X = 0' and `RETURN').