```
In response to mathiasrav at gmail dot com:
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The reason for that behavior is the parentheses. From the description:

"Parentheses may be used to force precedence, if necessary. For instance: (1 + 5) * 3 evaluates to 18."

So the order of operations says that even though the equality operator has higher precedence, the parentheses in your statement force the assignment operator to a higher precedence than the equality operator.

That said, it still doesn't work the way you expect it to. Neither way works, for these reasons:

<?php

if ( $a != ($a = $b) )

?>

Order of operations says to do the parentheses first. So you end up with:

<?php

$a = $b;

if ( $a != $a )

?>

Which is obviously going to be false. Without the parentheses:

<?php

if ( $a != $a = $b )

?>

Order of operations says to do the inequality first, then the assignment, so you have:

<?php

if ( $a != $a );

$a = $b;

?>

Which again is not what you expected, and again will always be false. But because you are only working with values of 0 and 1, you can make use of the XOR operator:

<?php

if ( $a ^= $b )

?>

This will only be true if 1) $a is 0 and $b is 1, or 2) $a is 1 and $b is 0. That is precisely what you wanted, and it even does the assignment the way you expected it to.

<?php

foreach ($ourstring as $c) {

if ($bold ^= $c['bold']) $resstring .= bold;

if ($underline ^= $c['underline']) $resstring .= underline;

$resstring .= $c[0];

}

?>

That code now works and produces the output you expected.