First, I am flattered for all the "elegant" comments. Honestly, this is PHP 102 level stuff, so I don't see all the fuss. Yes it is the ternary operator -- I'm a big fan of that one. (http://us.php.net/manual/en/language.expressions.php) In the below example, (while sloppy on my part), by NOT initializing the $r, it defaults to Boolean 'false' (not true as in the example), therefore !$r will be Boolean true. So this just keeps bouncing between the two each time. http://us.php.net/manual/en/language.variables.php "It is not necessary to initialize variables in PHP however it is a very good practice. Uninitialized variables have a default value of their type - FALSE, zero, empty string or an empty array." <?php echo ($unset_bool ? "true" : "false"); // false $unset_int += 25; // 0 + 25 => 25 echo $unset_string . "abc"; // "" . "abc" => "abc" $unset_array[3] = "def"; // array() + array(3 => "def") => array(3 => "def") ?> Anyways, I think everyone has analyzed this to death, and it's time for ya'll to get back to work! :) Just add it to your arsenal of 'snippets' and move on with your lives. HAHAH. Peace out yo. D.Vin http://daevid.com > -----Original Message----- > From: Jay Blanchard [mailto:jblanchard@xxxxxxxxxx] > Sent: Friday, October 05, 2007 11:39 AM > To: Robert Cummings; Jeff Cohan > Cc: php-general@xxxxxxxxxxxxx > Subject: RE: Alternate Colors in Rows ($r=!$r) > > [snip] > > > > But why does the ($r=!$r) ternary condition work?. (I understand > > that it DOES but not WHY.) > > Because he's rotating between boolean values. > > $r = true; > $r = !$r; // Now $r is false; > $r = !$r; // Now $r is true; > $r = !$r; // Now $r is false; > $r = !$r; // Now $r is true; > $r = !$r; // Now $r is false; > $r = !$r; // Now $r is true; > $r = !$r; // Now $r is false; > $r = !$r; // Now $r is true; > ... > [/snip] > > We just did that proof in the office as well. With a little > echoing you > will see that when $r is TRUE it is set to 1, when it is > false it is set > to NULL. > > But it still should not work logically because you are performing an > assignment in the IF (it doesn't have to be ternary to work, that is > just elegant). > > <?php > echo "<pre>"; > echo ($r = !$r)?"Yes\n":"No\n"; > echo $r."\n"; > echo ($r = !$r)?"Yes":"No"; > echo $r."\n"; > > if($r = !$r){ > echo "Yes\n"; > }else{ > echo "No\n"; > } > echo $r."\n"; > > > if($r = !$r){ > echo "Yes\n"; > }else{ > echo "No\n"; > } > echo $r."\n"; > echo "</pre>"; > ?> > > Returns > Yes > 1 > No > Yes > 1 > No > Yes > 1 > No > Yes > 1 > No > > It looks like PHP has an "unintentional feature". Doing this; if($r = > !$r) should always return TRUE because it is an assignment. I > don't know > if I would rely on this. > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
