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[SIC\]IF Logical_Expression [THEN]
[SIC\]IF Logical_Expression Command [Arguments]
The first form starts a conditional IF block. The behaviour of IF blocks
is similar to structured Fortran. The THEN keyword is optional.
The second form defines a logical IF statement, i.e. it uses a single
line with no possibility of alternate execution (no ELSE choice). When
the argument following the logical expression is not THEN, it is assumed
to be a command which will be interpreted, together with the next argu-
ments, if the logical expression evaluates as true.
This command can only be used within a procedure: interactive users are
expected to be able to make their decisions themselves.
There must be no blanks within the logical expression, but composite ex-
pressions are allowed. Two special logical functions can also be used:
- EXIST(VarName) Returns .TRUE. if VarName is an existing variable
- FILE("String") Returns .TRUE. if String is an existing file. Double
quotes protect the case of the string. Syntax FILE("'VarName'")
allows to check the string contained in a character variable.