issue in selecting value in pagination - php

Question

I think i am very near to my correct answer. I found one code on this forum like i wrote below.but it didn't work for me.Whats wrong with this code???
<?php
include("config.php");
$start = 0;
$per_page = 10;
$targetpage = "manual.php?id=$id"; // This is my target page
if(!isset($_GET['page'])){
$page = 1;
} else{
$page = $_GET['page'];
}
if($page<=1)
$start = 0;
else
$start = $page * $per_page - $per_page;
........................
.............................
.................?>
The answer which i saw contains id=42 in $targetpage = "manual.php?id=$id";But i don't understand why he used 42 there???
Then linking target page in next previous code as follows
<?php
if($page > 1){
$prev = $page - 1;
$prev = " <a href=\'$targetpage&page=$prev'>prev</a> ";
} else {
$prev = "";
}
if($page < $num_pages){
$next = $page + 1;
$next = " <a href=\'$targetpage&page=$next'>next</a> ";
}
else
{
$next = "";
}
echo $prev;
echo $next;
?>
But it gives me error like \'manual.php is not found..But i have this file.

Answer 1

just a guess, try to use:
$targetpage = "./manual.php?id=$id";
if it doesn't work then it means you are specifying the wrong URL to your manual.php page, try to find the correct URL
and id=42 it's an application specific parameter so it's related to that app so it's okay if you don't use it in your app.