WHILE


WHILE

     WHILE causes the commands within a WHILE block to be executed
repetitively as long as a specified condition is true. A WHILE
block consists of all the commands between the WHILE and ENDWHILE commands.

SYNTAX

     WHILE expression [DO]


PARAMETERS

expression          Logical expression, consisting of operands and
relational operators. The DO keyword is optional.
It may be used or omitted and has no affect on the results.

The WHILE command evaluates expression and displays
the result (TRUE or FALSE) to $STDLIST. If
expression does not resolve to a boolean result,
an error is reported.

OPERATION

     This command begins a looping construct that consists of
all the commands lying between WHILE and the next ENDWHILE
statement. The ENDWHILE must have the same nesting level
as the WHILE statement. The ENDWHILE statement ends the
WHILE block.

Expression is evaluated and as long as expression
evaluates to TRUE, the WHILE block is executed.

You may not write a WHILE construct in such a way that a WHILE
begins in one User Command (UDCs or command files) and its
corresponding ENDWHILE concludes the loop in another User Command.

o To see a list of expression evaluator functions, type
FUNCTIONS at the HELP prompt. Or, you may enter an
individual function name for more specific information.

o To see a list of FINFO options, type FINFO at the HELP prompt.

o To see a list of predefined MPE/iX variables, type VARIABLES
at the HELP prompt. Or, you may enter an individual variable
name for more specific information.

This command may be issued from a session, job, in BREAK, or
from a program. Pressing [Break] aborts the execution of this command.

EXAMPLE(S)

The following is an example of the WHILE command:

WHILE SETVAR (filename, input("Enter the next filename &
to purge: ")) <> "" DO
CONTINUE
PURGE !filename
ECHO ![ups(filename)] has been purged.
ENDWHILE

This section of code will continue to ask for and purge files until the
user enters a [Return] or the name of a file that does not exist.

ADDITIONAL INFORMATION

Commands:   DELETEVAR, ELSE, ELSEIF, ENDWHILE, IF, RETURN,
SETJCW, SHOWJCW, SETVAR, SHOWVAR; see also FUNCTIONS
and VARIABLES

Manuals : Appendix B, "Expression Evaluator Functions," in the
MPE/iX Commands Reference Manual (32650-90003)