Re: Define field as an indicator in D-specs

On 12/6/2013 2:59 PM, Jon Paris wrote:

That is certainly the case in PHP for example, but if I recall correctly there are certainly situations in RPG where non '1' values will evaluate to false - but not a good idea to rely on it I'm sure but ... I just recall having to try to understand code where someone had set an indicator to either '1', 'A', or 'B' or some such.

Just ran a quick test and that appears to hold true for the current version of RPG IV - so in most cases at least RPG appears to be the reverse. i.e. True = 1 and False = not 'True.

RPG isn't consistent though. Both DSPLYs are done in this program, so it's both false and true.

D fld s 10a inz('a')
C move fld *in10
C 10'cond t' dsply
C N10'ncond t' dsply
C return

Many languages specifically define that 0 is false and anything else is true. But for RPG, it's undefined what will happen if an indicator doesn't have the value '0' or '1'.

With RPG, since it's undefined behaviour, the compiler is free to generate code to compare the indicator to either '0' or '1' depending on which makes more sense for that specific case.