note 52969 added to function.str-replace

Why this example will output " b a " instead of " b b "? <?php $search = " a "; $replace = " b "; $subject = " a a "; echo str_replace($search, $replace, $subject); ?> ---- Manual Page -- http://www.php.net/manual/en/function.str-replace.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+52969 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+52969&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+52969&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+52969&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+52969&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+52969&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+52969&report=yes Search -- http://master.php.net/manage/user-notes.php