Learning php paging code instances

When learning PHP, you will surely encounter the problem of operating the MYSQL database and displaying the data in the database by page. Below is a small example to learn the PHP paging method. PHP paging has many methods. today we will use a small example to demonstrate this function.
The code is as follows:
$ Result ="

";

// Previous Page
If ($ offset> 0 ){
$ Result. ="
• 
  Prev
  
";
}

$ Pages = $ allPageNums; // total number of pages
$ Page = $ curPage; // Current page number
$ Page_len = 9;
$ Page_len = ($ page_len % 2 )? $ Page_len: $ pagelen + 1; // Number of page numbers
$ Pageoffset = ($ page_len-1)/2; // page number offset between left and right
If ($ pages> $ page_len ){
// If the current page is less than or equal to the left offset
If ($ page <= $ pageoffset ){
$ Init = 1;
$ Max_p = $ page_len;
} Else {// if the current page is greater than the left offset
// If the right offset of the current page number exceeds the maximum page number
If ($ page + $ pageoffset >=$ pages + 1 ){
$ Init = $ pages-$ page_len + 1;
$ Max_p = $ pages;
} Else {
// Calculation when both the left and right offsets exist
$ Init = $ page-$ pageoffset;
$ Max_p = $ page + $ pageoffset;
}
}
} Else {
　　
$ Init = 1;
$ Max_p = $ pages;
}

For ($ I = $ init; $ I <= $ max_p; $ I ++ ){

If ($ I ==$ curPage ){
$ Result. ="

• $ I
";
Continue;
}

$ Result. ="
• $ I
";

}

// Print the next page
If ($ allnums> ($ offset + $ maxrow )){
$ Result. ="
• 
  Next
  
";
}