The CASE construct is a replacement for the computed GOTO, but is better structured and does not require the use of statement labels:
SELECT CASE (number) ! NUMBER of type integer
CASE (:-1) ! all values below 0
n_sign = -1
CASE (0) ! only 0
n_sign = 0
CASE (1:) ! all values above 0
n_sign = 1
END SELECT
Each CASE selector list may contain a list
and/or range of integers, character
or logical constants, whose values may not overlap within or
between selectors:
CASE (1, 2, 7, 10:17, 23)
A default is available:
CASE DEFAULT
There is only one evaluation, and only one match.
A simplified but sufficient form of the DO construct is illustrated by
outer: DO
inner: DO i = j, k, l ! only integers
:
IF (...) CYCLE
:
IF (...) EXIT outer
END DO inner
END DO outer
where we note that loops may be named so that the EXIT and CYCLE
statements may specify which loop is meant.
Many, but not all, simple loops can be replaced by array expressions and assignments, or by new intrinsic functions. For instance
tot = 0.
DO i = m, n
tot = tot + a(i)
END DO
becomes simply
tot = SUM( a(m:n) )