VMS Help Lexicals, F$ELEMENT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Extracts one element from a string of elements.

    Format

      F$ELEMENT(element-number, delimiter, string)

1 - Return Value

    A character string containing the specified element.

2 - Arguments

 element-number

    Specifies the number of the element to extract (numbering begins
    with zero). Specify the element-number argument as an integer
    expression. If the element-number argument exceeds the number of
    elements in the string, F$ELEMENT returns the delimiter.

 delimiter

    Specifies a character used to separate the elements in the
    string. Specify the delimiter as a character string expression.

 string

    Specifies a string containing a delimited list of elements.
    Specify the string as a character string expression.

3 - Examples

    1.$ DAY_LIST = "MON/TUE/WED/THU/FRI/SAT/SUN"
      $ INQUIRE DAY "ENTER DAY (MON TUE WED THU FRI SAT SUN)"
      $ NUM = 0
      $ LOOP:
      $       LABEL = F$ELEMENT(NUM,"/",DAY_LIST)
      $       IF LABEL .EQS. "/" THEN GOTO END
      $       IF DAY .EQS. LABEL THEN GOTO 'LABEL'
      $       NUM = NUM +1
      $       GOTO LOOP
      $
      $ MON:
         .
         .
         .

      This example sets up a loop to test an input value against the
      elements in a list of values. If the value for DAY matches
      one of the elements in DAY_LIST, control is passed to the
      corresponding label. If the value returned by the F$ELEMENT
      function matches the delimiter, the value DAY was not present
      in the DAY_LIST, and control is passed to the label END.

    2.$ ! INDEX.COM
      $ !
      $ CHAPTERS = "0,1,2,3,4,5,6,A,B,C"
      $ NEXT = 0
      $ LOOP:
      $   NEXT = NEXT + 1
      $   NUM = F$ELEMENT(NEXT,",",CHAPTERS)
      $   IF (NUM .NES. ",")
      $   THEN
      $      RUN INDEX CHAP'NUM'
      $      GOTO LOOP
      $   ENDIF

      This example processes files named CHAP1, CHAP2, ... CHAP6,
      CHAPA, CHAPB, and CHAPC, in that order. (Zero is included in
      the CHAPTERS string to initialize the procedure logic.) NEXT
      is initialized to zero. The procedure enters the loop. In the
      first iteration, NEXT is incremented to 1 and the result of the
      F$ELEMENT call is the string "1". The procedure runs the index,
      chapter 1. In the second iteration, NEXT is incremented to 2
      and the result of the F$ELEMENT call is the string "1". The
      procedure runs the index, chapter 2. Processing continues until
      the result of the F$ELEMENT call is the delimiter specified in
      the call.