RE: [PHP] A really wacky design decision

And then you discover === $i = 0; $j = count ($names); while ($i < $j) { if ($names[$i] === $target) { break; } ++$i; } ... regards > To: php-general@lists.php.net > From: clancy_1@cybec.com.au > Date: Sat, 3 Oct 2009 21:21:00 +1000 > Subject: [PHP] A really wacky design decision > > Daevid Vincent is surprised that: > > $num = 123; > $num = $num++; > print $num; //this prints 123 and not 124 ?!! > > To me this is relatively logical. As I understand it, the post-increment operator says "do > something with the variable, and then increment it. The trouble in this case is that we > are doing something irrational; we are copying the number back to itself, and to me it is > reasonably logical (or at least no less illogical than the alternative) to assume that if > we copy it to itself, then increment the original version, the copy will not be > incremented. > > However there is one feature of PHP which, to my mind, is really bad design. How many of > you can see anything wrong with the following procedure to search a list of names for a > particular name? > > $i = 0; $j = count ($names); while ($i < $j) > { if ($names[$i] == $target) { break; } > ++$i; > } > > As long as the names are conventional names, this procedure is probably safe to use. > However if you allow the names to be general alphanumeric strings, it is not reliable. One > of my programs recently broke down in one particular case, and when I eventually isolated > the bug I discovered that it was matching '2260' to '226E1'. (The logic of > this is: 226E1 > = 226*10^1 = 2260). > > I agree that I was well aware of this trap, and that I should not have used a simple > comparison, but it seems to me to be a bizarre design decision to assume that anything > which can be converted to an integer, using any of the available notations, is in fact an > integer, rather than making the default to simply treat it as a string. It is also a trap > that it is very easy to fall into if you start off thinking about simple names, and then > extend (or borrow) the procedure to use more general strings. > > And can anyone tell me whether, in the above case, it is sufficient to write simply: > if ((string) $names[$i] == $target), > > or should I write: > if ((string) $names[$i] == (string) $target)? > > (I decided to play safe and use strcmp ().) > > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > _________________________________________________________________ Windows Live: Keep your friends up to date with what you do online. http://www.microsoft.com/middleeast/windows/windowslive/see-it-in-action/social-network-basics.aspx?ocid=PID23461::T:WLMTAGL:ON:WL:en-xm:SI_SB_1:092010