Beautiful paging method implemented in php_PHP tutorial

/**
* Get paginated HTML content
* @param integer $page current page
* @param integer $pages total number of pages
* @param string $url jump url address The last page number starts with '&page=x' appended to the end of the url
*
* @return string HTML content;
*/
public static function getPageHtml($page , $pages, $url){
//The maximum number of page numbers to display
$_pageNum = 5;
//If the current page is less than 1, it is 1
$page = $page<1?1 :$page;
//If the current page is greater than the total number of pages, the total number of pages is
$page = $page > $pages ? $pages : $page;
//If the number of pages is less than the current page For the current page
$pages = $pages < $page ? $page : $pages;

//Calculate the start page
$_start = $page - floor($_pageNum/2);
$_start = $_start<1 ? 1 : $_start;
//Calculate the end page
$_end = $page + floor($_pageNum/2);
$_end = $_end> $pages? $pages : $_end;

//The number of pages currently displayed is not enough for the maximum number of pages. Adjust left and right
$_curPageNum = $_end-$_start+1;
/ /Left adjustment
if($_curPageNum<$_pageNum && $_start>1){
$_start = $_start - ($_pageNum-$_curPageNum);
$_start = $_start<1 ? 1 : $_start;
$_curPageNum = $_end-$_start+1;
}
//Adjust right
if($_curPageNum<$_pageNum && $_end<$pages){
$ _end = $_end + ($_pageNum-$_curPageNum);
$_end = $_end>$pages? $pages : $_end;
}

$_pageHtml = '

';
/*if($_start == 1){
$_pageHtml .= '
• «';
  }else{
  $_pageHtml .= '
';
}*/
if($page>1){
$_pageHtml .= '
• «
';
}
for ($ i = $_start; $i <= $_end; $i++) {
if($i == $page){
$_pageHtml .= '
• < a>'.$i.'
';
}else{
  $_pageHtml .= '
• '.$i.'
';
}
}
/*if($_end == $pages ){
$_pageHtml .= '
• »
';
}else{
$_pageHtml .= '
• »
';
}*/
if($page<$_end){
$_pageHtml .= '
• »
';
}
$_pageHtml .= '

';
echo $_pageHtml;
}