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run code in 300+ PHP versions simultaneously
<?php $body = <<<HTML <body class="old_attr"> <div>(content)</div> </body> HTML; $new_class = "new_class_attr"; $body = preg_replace('~<body[^>]*class *= *["\']\K~', "$new_class ", $body, 1, $count); if (!$count) { $body = preg_replace('~<body\K~', " class=\"$new_class\"", $body, 1); } echo $body;

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