LOOP

LOOP allows the programmer to specify loops with multiple exit conditions.

COMMAND SYNTAX

    LOOP statements1 WHILE | UNTIL expression DO statements2 REPEAT

SYNTAX ELEMENTS

statements1 and statements2 consist of any number of standard statements include the LOOP statement itself, thus allowing nested loops.

statements1 will always be executed at least once, after which the WHILE or UNTIL clause is evaluated.

expression is tested for Boolean TRUE/FALSE by either the WHILE clause or the UNTIL clause. When tested by the WHILE clause statements2 will only be executed if expression is Boolean TRUE. When tested by the UNTIL clause, statements2 will only be executed if the expression evaluates to Boolean FALSE.

REPEAT causes the loop to start again with the first statement following the LOOP statement.

NOTES

See also: BREAK, CONTINUE

EXAMPLE

      IF NOT( GETENV('TAFC_HOME', V.HOME) ) THEN
          CRT 'TAFC_HOME not defined'
          STOP
       END
      EXECUTE 'SELECT ' : V.HOME : '/jbcmessages SAMPLE 10' RTNLIST V.MSG.L
    * Retrieve @IDs one by one
       LOOP
          REMOVE V.ID FROM V.MSG.L SETTING V.STATUS
          CRT V.ID
          IF V.STATUS EQ 0 THEN BREAK   ;* end of list reached
       REPEAT

Output looks like: 

     INV_FILE_TYPE
     DEVICE_QUIT
     RTN_NOGOSUB
     ARRAY_ILLEGAL_SIZE
     DIFF_COMMON
     QLNOVERB
     QLPARAMERR
     SP-HoldCount
     603
     1134

The loop used in this example can also be defined this way: 

       LOOP
          REMOVE V.ID FROM V.MSG.L SETTING V.STATUS
          CRT V.ID
       UNTIL V.STATUS EQ 0
       REPEAT
Last update: Sat, 16 Jul 2022 15:34