9.3.118 PRESENT (A)

Description:  Returns whether or not an optional dummy argument is present (has an associated actual argument).  
Class:  Inquiry function; Generic 
Arguments:  A must be an optional argument of the current procedure. 
Results:  The result is a scalar of type default logical. The result is .TRUE. if A is present; otherwise, the result is .FALSE.. 

Examples

Consider the following:

SUBROUTINE CHECK (X, Y)
  REAL X, Z
  REAL, OPTIONAL :: Y
  ...
  IF (PRESENT (Y)) THEN
    Z = Y
  ELSE
     Z = X * 2
  END IF
END
...
CALL CHECK (15.0, 12.0)      ! Causes B to be set to 12.0
CALL CHECK (15.0)            ! Causes B to be set to 30.0


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