Re: %DEC problems -- RPG400-L

Hello,

Trying to figure out why the following /free code is blowing raspberriesat me:


   cuPD   = %dec( %char( %date : *ISO0 )
                : %len( cuPD )
                : %decpos( cuPD )        );

cuPD is defined as P(8,0) in a database file defined for output.  The
compiler errors I'm getting are related to the 2nd & 3rd parameters of
the %dec BIF:

The %DEC() BIF can be used to control intermediate representations and hasa big impact on the way that the code gets compiled. Since that's thecase, the 2nd and 3rd parameters to this BIF need to be known at compiletime -- after all, how can it control the way that the code is compiled ifit doesn't know what the sizes of the fields are until the program isrunning?

However, the %len() BIF calcualtes the length at runtime instead ofcompile time. That obviously creates problems! So you can't use %len()in a parameter of %dec().

One simple solution is to FORCE %len() to be done at compile time by usingit as part of a constant. For example, the following code should work:


     D cuPDLen         c                   const(%len(cuPD))
     D cuPDDec         c                   const(%decpos(cuPD))

      /free

            cuPD = %dec( %char( %date: *ISO0 )
                       : cuPDLen
                       : cuPDDec );

The reason it solves the problem is that %len() is being used as part of aconstant. Constants are always defined at compile-time and can't bechanged during a program run. That way, RPG feels safe in using thevalues at compile-time.

However, in your particular situation, I wouldn't use %dec() at all, I'duse %int() because it makes the code easier to read. I don't understandwhy you're using %dec() here, since the result of the expression doesn'thave to be the exact same data type and size as the variable you'reassigning it to.

Just as you can assign a value from a packed field to a zoned field, orthe value of a literal to a packed field, you can assign the value of aninteger to a packed(8,0) field quite easily.

So I'd use %int(), and accomplish the same thing in 1 line of code thattook 5 lines, above. As follows:


           cuPD = %int( %char( %date: *ISO0) );

I think that code will be easier for the next guy to read, and thereforewill make program maintenace easier.