<?php

$variavel='123';

$heredoc = <<<CODE
rand@#¨4key"'?></ <\\\\ $variavel \0
CODE;

$nowdoc = <<<'CODE'
rand@#¨4key"'?></ <\\\\ $variavel \0
CODE;


echo $heredoc . PHP_EOL;

echo $nowdoc . PHP_EOL;