Re^2: if/else syntax

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Re^3: if/else syntax by ikegami (Patriarch) on Jun 26, 2009 at 16:49 UTC
(a?b:c) also has those problems right ? No, because the "`:`" isn't optional like `else` is, and because people don't indent the conditional operator like they would an if/else. It has a different problem, though. A frequent mistake with the conditional operator is to use it as follows: `$c ? $x = $i : $y = $j;` [download] The above means `( $c ? $x = $i : $y ) = $j;` [download] but people expect it to mean `$c ? ($x = $i) : ($y = $j);` [download]	[reply] [d/l] [select]
Re^4: if/else syntax by Anonymous Monk on Jun 26, 2009 at 17:05 UTC
a thats true. indeed, the fact that ":" isn't optional changes everything, now it makes more sense. thanks.	[reply]
Re^3: if/else syntax by Crackers2 (Parson) on Jun 26, 2009 at 16:10 UTC
I don't think so. With if/else: `if a if b c else d` [download] could mean `if a { if b { c } else { d } } or if a { if b { c } } else { d }` [download] With the ternary operator that would be `a ? b ? c : d : () and a ? b ? c : () : d` [download] so there's no abmbiguity.	[reply] [d/l] [select]
Re^4: if/else syntax by gwadej (Chaplain) on Jun 26, 2009 at 16:44 UTC
There's actually no ambiguity in the C syntax for your example. The compiler understands it fine. The problem is that the programmer/reader of the code does not always read it the same way. `if(a) if(b) c(); else d();` [download] According to what I recall, the `else` matches with the nearest `if` in this case. Unfortunately, indentation gives humans fits on this. `if(a) if(b) c(); else d();` [download] This does the same thing (`else` goes with `if(b)`). As I said, there's nothing ambiguous about it. G. Wade	[reply] [d/l] [select]
Re^5: if/else syntax by Anonymous Monk on Jun 26, 2009 at 17:01 UTC
thanks, thats exactly what I'm trying to say, if the programmer knows how the compiler interprets the code he can use it in the right way.	[reply]
Re^5: if/else syntax by ikegami (Patriarch) on Jun 26, 2009 at 17:20 UTC
The compiler understands it fine. Not true. How can the compiler understand it fine when C doesn't define it `if(a) if(b) c(); else d();` [download] means `if(a) { if(b) c(); else d(); }` [download] or `if(a) { if(b) c(); } else d();` [download] Both are right. Neither is right. I don't know if that was fixed in recent versions of C. There's actually no ambiguity in the C syntax for your example. That's not true either. You contradict yourself in the next sentence. You write code for both people and for compilers to read. Ambiguity for either is still ambiguity. Anyway, the topic wasn't ambiguity but (the avoidance of) traps. C's if/else definitely has pitfalls.	[reply] [d/l] [select]
Re^6: if/else syntax by massa (Hermit) on Jun 26, 2009 at 17:33 UTC
Re^6: if/else syntax by gwadej (Chaplain) on Jun 29, 2009 at 13:34 UTC
Re^4: if/else syntax by Anonymous Monk on Jun 26, 2009 at 16:27 UTC
so why we can't have a if/else syntax without brackets that behaves just like the ternary operator ? `if a { if b { c } else { d } } or if a { if b { c } } else { d }` [download] Does not matter who the compiler will assume, since if it get implemented we would know it before hand	[reply] [d/l]
Re^5: if/else syntax by Transient (Hermit) on Jun 26, 2009 at 17:21 UTC
Perhaps this will add a bit of enlightenment as to the reasoning behind the exclusion: http://www.nntp.perl.org/group/perl.perl6.language/2004/05/msg17372.html `"We think that nowadays we can edge away from some of the less useful C heritage, as long as we stay close enough to our Perl heritage. (Some would say we've already blown it there... :-)"` [download]	[reply] [d/l]
Re^3: if/else syntax by dreadpiratepeter (Priest) on Jun 26, 2009 at 15:51 UTC
what you are looking for is: `if ($cond==1) { do_good(); } else { do_bad(); }` [download] -pete "Worry is like a rocking chair. It gives you something to do, but it doesn't get you anywhere."	[reply] [d/l]