Re: MLLZO Usge

[Douglas Handy <dhandy1@xxxxxxxxxxxxx>]

A.,

>I am looking for more information MLLZO opcode. I would like to know (with
>example) under what circumstances this opcode needs to be used.

To a large extent, this opcode fell into disuse when people quit using punched
cards, but RPG has a (good) habit of always allowing existing code to get
recompiled with no changes, so the opcode will probably always remain available
-- at least in the fixed form layout version.

The only use I can see for it these days is to force a numeric variable's sign
to either positive or negative, or to force it to match another variable's sign.

Examples:

    MLLZO'0'       ABSVAL      will force a variable to absolute value
    MLLZO'J'       NEGVAL      will force a variable to negative
    MLLZOFOO       BAR        will force a BAR to the sign of FOO

all of these would be very quick opoerations relative to testing the variable
and using IF blocks.  However, unless the code was in an iterative loop not
interrupted by I/O operations, the performance difference would be like
Barbara's great comparison of standing on a chair to get closer to the moon.

For the next programmer who came along, the MLLZO would be less intuitive and
readable than just doing explicit tests.

Doug