Re: %LEN and *ZERO

[boldt@xxxxxxxxxx]

Simon wrote:
>Why does the RPG IV compiler reject the following line with RNF7563?
>  C         EVAL %LEN(cmdString) = *ZERO
>when cmdString is defined as:
>  D cmdString       S         5768    VARYING
> ...

then Barbara wrote:
>The obvious circumvention is to use 0, but a better one is to assign
>the null literal '' to cmdString.

Well, assigning '' to the string may involve typing fewer characters
in the RPG program, but setting the length directly generates a lot
fewer W-Code instructions.  At no optimization, this means that
assigning '' to the string is substantially slower.   (It's hard to
compare performance with any optimization due to the aggressiveness
of the optimizer.)

I really have no opinion on which is better programming style.
Another alternative is "CLEAR cmdString;", which generates the same
code as setting %LEN to 0.

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com

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