9.219 PRESENT — Determine whether an optional dummy argument is specified

Description:

Determines whether an optional dummy argument is present.

Standard:

Fortran 90 and later

Class:

Inquiry function

Syntax:

RESULT = PRESENT(A)

Arguments:

A	May be of any type and may be a pointer, scalar or array value, or a dummy procedure. It shall be the name of an optional dummy argument accessible within the current subroutine or function.

Return value:

Returns either TRUE if the optional argument A is present, or FALSE otherwise.

Example:

PROGRAM test_present
  WRITE(*,*) f(), f(42)      ! "F T"
CONTAINS
  LOGICAL FUNCTION f(x)
    INTEGER, INTENT(IN), OPTIONAL :: x
    f = PRESENT(x)
  END FUNCTION
END PROGRAM