PHP 문자열의 표현 방법은 무엇입니까?

<?php
$name = &#39;php&#39;;
@header("Content-type: text/html; charset=utf-8"); 
echo &#39;最简单的字符串表达形式&#39;."\n";
 
echo &#39;可以是
多行的&#39;."\n";
 
echo &#39;单引号"\&#39;"和反斜杠"\\"需要使用"\"转义&#39;."\n";
 
echo &#39;"\\"与"\"是一样的&#39;."\n";
 
echo &#39;其他特殊字符如\n、\r和变量$name是不会转换的&#39;."\n";
?>

<?php
$name = &#39;php&#39;;
@header("Content-type: text/html; charset=utf-8"); 
 
echo "双引号中单引号&#39;不需要转义反斜杠\也不需要转义双引号\"需要转义\n";
 
echo "双引号也可以是
		多行的\n";
 
echo "\"\\\\\"与\"\\\"是一样的，但是如果想要表示两个反斜杠则需要使用四个反斜杠\n";
 
echo "还可以转义其他一些特殊字符，如：\\\$转义为\$，\\x41转义为\x41\n";
 
echo "还可以解析变量，如：\\\$name解析为$name\n";
?>

<?php
@header("Content-type: text/html; charset=utf-8"); 
 
$name = &#39;php&#39;;
function foo(){
	static $str = <<<EOS
\n
\r
\t
\v
\e
\f
\
\\
\\\\\
\$name
\"
\&#39;
\x41
\072
EOS;
echo $str;
}
foo();
 
/* 含有变量的更复杂示例 */
class foo
{
    
	const cons= <<<"EOD"
cons
EOD;
	var $test= <<<EOD
"test"
EOD;
	var $bar;
    function foo()
    {
        $this->bar = array(&#39;Bar1&#39;, &#39;Bar2&#39;, &#39;Bar3&#39;);
    }
}
 
$foo = new foo();
echo foo::cons."\n";
echo <<<EOT
heredoc中支持更复杂的格式如：
\$foo->test=> $foo->test.
{\$foo->bar[1]}=>{$foo->bar[1]}.
EOT;
?>

<?php
@header("Content-type: text/html; charset=utf-8"); 
 
$name = &#39;php&#39;;
function foo(){
	static $str = <<<&#39;EOS&#39;
$name
\n
\r
\t
\v
\e
\f
\
\\
\\\\\
\$name
\"
\&#39;
\x41
\072
EOS;
echo $str;
}
foo();
 
/* 含有变量的更复杂示例 */
class foo
{
    
	const cons= <<<&#39;EOD&#39;
cons
EOD;
	var $test= <<<&#39;EOD&#39;
"test"
EOD;
	var $bar;
    function foo()
    {
        $this->bar = array(&#39;Bar1&#39;, &#39;Bar2&#39;, &#39;Bar3&#39;);
    }
}
 
$foo = new foo();
echo foo::cons."\n";
echo <<<&#39;EOT&#39;
nowdoc中不支持复杂的格式如：
\$foo->test=> $foo->test.
{\$foo->bar[1]}=>{$foo->bar[1]}.
EOT;
?>