What are the advantages of phpfunction? Solution

What are the advantages of phpfunction? What are the advantages of PHP & nbsp; function & nbsp? & Nbsp; can the array be cleared automatically, variables be cleared, and MEMORY is cleared? $ Array & nbsp; array (www.google.com.hk, www.baidu.com, www.1.com, what are the advantages of php functions?
What are the advantages of PHP functions? Can the array be automatically cleared, variables cleared, and MEMORY cleared?

$array = array('http://www.google.com.hk','http://www.baidu.com','http://www.1.com/','http://www.yahoo.com.cn');
foreach($array as $url){
    $ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)');
$html = curl_exec($ch);
curl_close($ch);
echo $html.'
 ';
$html = NULL;
        unset($html);
}

function get_html($url){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)');
$html = curl_exec($ch);
curl_close($ch);
return $html;
}
$array = array('http://www.google.com.hk','http://www.baidu.com','http://www.1.com/','http://www.yahoo.com.cn');
foreach($array as $url){
    get_html($url);
}

If it is a function, do you also need an unset array?
Or is the array automatically cleared when the first function is executed as long as return?


------ Solution --------------------
I don't know what it means for the two questions that follow you.
In fact, you can use functions to encapsulate function implementation. isn't the code better?
------ Solution --------------------
Unset and unset methods do not matter... the function writing method makes it easier for you to call the code structure at any time...