J3/05-218 Date: 22 July 2005 To: J3 From: Rob James Subject: Null input values and list-directed UDDTIO NUMBER: F03/0056 TITLE: Null input values and list-directed UDDTIO KEYWORDS: null value, UDDTIO DEFECT TYPE: Interpretation STATUS: J3 consideration in progress QUESTION: Consider the following program: MODULE m PRIVATE TYPE, PUBLIC :: t INTEGER i INTEGER j CONTAINS PROCEDURE, PRIVATE :: readFormatted => readFormattedT GENERIC :: READ(FORMATTED) => readFormatted END TYPE CONTAINS SUBROUTINE readformattedT(dtv, unit, iotype, v_list, iostat, iomsg) CLASS(t), INTENT(INOUT) :: dtv INTEGER, INTENT(IN) :: unit CHARACTER(*), INTENT(IN) :: iotype INTEGER, INTENT(IN) :: v_list(:) INTEGER, INTENT(OUT) :: iostat CHARACTER(*), INTENT(INOUT) :: iomsg READ (unit, *) dtv%i READ (unit, *) dtv%j END SUBROUTINE END MODULE PROGRAM p USE m INTEGER i TYPE(t) x, y, z x%i = 10 x%j = 15 y%i = 20 y%j = 25 z%i = 30 z%j = 35 i = 100 READ (*,*) x, y, z, i PRINT *, x, y, z, i END PROGRAM The following is given as input to this program: 1044 2167 3977 / 1 2 3 10.9.1.1 of Fortran 2003 (Null values) states: A slash encountered as a value separator during execution of a list-directed input statement causes termination of execution of that input statement after the assignment of the previous value. If a child data transfer statement encounters a slash as a value separator, it is unclear whether this statement applies to just the child statement, or to the parent data transfer statement as well. The significance for any subsequent child statement is also unclear. What is the behaviour of this program when it is given the specified input? ANSWER: When a child data transfer statement encounters a slash as a value separator, only that data transfer statement encounters the slash. None of its parent data transfer statements encounters the slash. Only the data transfer statement that encounters the slash is terminated. The program above should print the following: 1044.2167.3977.25.1.2.3 where "." represents a value separator. EDITS: None. SUBMITTED BY: Rob James HISTORY: 05-171 m172 Submitted 05-218 m173 Answer provided