Christophe Herreman

No Responses to “i += i++ + ++i;”

1. Philippe Says:
   May 27th, 2006 at 12:02 pm

   Haha, nice!
   I guessed the correct result.

2. Kristof Says:
   May 27th, 2006 at 4:42 pm

   In actionscript, javascript, java and vbscript it is 5

   var i:Number;
   i = 1;
   i += i++ + ++i;
   trace(”i = “+i);

   i = 1;
   i = i+i+(i+1);
   i++;
   trace(”i = “+i);

   i = 1;
   i = 3*i+2;
   trace(”i = “+i);

   In php and c++ however this would be 7 …

   ‘;

   $i = 1;
   $i++;
   $i = $i + $i + $i;
   $i++;
   echo ‘i = ‘, $i, ”;

   $i = 1;
   $i = (3 * ($i + 1)) + 1;
   echo ‘i = ‘, $i, ”;
   ?>

   And in ruby it would be 3.

   i = 1
   i += i++ + ++i
   puts ‘i = ‘ + i.to_s

   i = 1
   i = 3 * i
   puts ‘i = ‘ + i.to_s

   My head hurts.

3. caprica Says:
   May 27th, 2006 at 5:49 pm

   It seems that only actionscript, javascript, java and vbscript does this right ?

   i = 1
   i += i++ + ++i

   first operate on the right side :

   1st operation i++ => right_ans = 2
   2nd operation + (i is still 1) => right_ans = 2 + 1 = 3
   3rd operation ++i => right_ans = 3 + 1 = 4

   then operate on the left side :

   i = i + right_ans = 1 + 4 = 5

4. Kristof Says:
   May 29th, 2006 at 1:48 am

   @ caprica: Depends on your definition of right.

   Actionscript:
   var i = 1;
   i += ++i;
   trace(i); // traces 3
   //is equivalent to
   var i = 1;
   var oldi = i;
   var x = ++i;
   i = oldi + x;
   trace(i); //traces 3

   Php:
   $i = 1;
   $i += ++$i;
   echo ‘i = ‘, $i, ‘<br>’; // echos 4
   //is equivalent to
   $i = 1;
   $x = ++$i;
   $i = $i + $x;
   echo ‘i = ‘, $i, ‘<br>’; // echos 4

   Ruby:
   Ruby doesn’t support the increment operator.
   So you can write ++ all you want, it will just ignore you.

   Each of these approaches makes sense, they just happen to differ.

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