Can You Echo A $Var That Is Defined Later On In The Script?

icthos · November 9, 2012

Can you echo a $var that is defined later on in the script?

Ive got a good grasp of PHP basics but Im struggling in building a control structure that addresses this problem. I am making a web application that can be simplified to this:

<?php

include('functions.php');

include('head.php');

include('body.php');

?>

functions.php connects to the database etc, but for ease of explanation it is just this:

<?php $pageNumber = 6; ?>

head.php contains basic HTML head code with a dynamic stylesheet loader

<!doctype html>

<html>

<head>

</head>

body.php contains basic body template code, and gets its actual contents from another file

<body>

<?php include($pageNumber.".php"); ?>

</div>

</body>

</html>

And then as we are on page 6, page 6 contains:

<?php

$stylesheet = "yellow";

?>

<p>This is page six! You will notice that page six is coloured yellow, unlike any of the other pages</p>

I need to be able to control which stylesheet loads at the level of this page. I could put the stylesheet inclusion code after the include($pageNumber) part but then it wouldnt validate. Is there any way I can make it look futher on in the code for the value of $stylesheet if it isnt defined yet? Or is there a better control structure?

MDCode · November 9, 2012

Php goes line by line so no, why not just put the variable at the top?

Andy123 · November 10, 2012

No, you cannot do that. It's like you trying to predict what's on the next page of a book without reading it. You would have to come up with a different structure. Off the top of my head, you would either have to store this information in a file/database so that you can read it at the top, or you would probably have to use classes. For instance, many frameworks allow you to add items to the head of the rendered HTML from the view class. I haven't exactly done anything like this myself, though. The first option is by far the easiest, but also the less flexible one.

floridaflatlander · November 10, 2012

Off the top of my head, you would either have to store this information in a file/database so that you can read it at the top, or you would probably have to use classes.

Also you could try a cookie or session

MDCode · November 10, 2012

Ok, your organization made it hard to read first but I believe you said you get the page number from functions.php? If so you can do a simple check after you include it and before you include head.php:

if($pageNumber == "6") {
$stylesheet = yellow;
}

Andy-H · November 10, 2012

// styles.php
$stylesheets = array(1 => 'red', 'green', 'blue', 'black', 'purple', 'yellow');

<?php
include('functions.php');
include('styles.php');
include('head.php');
include('body.php');
?>

<?php $pageNumber = 6; ?>

<!doctype html>
<html>
<head>
<link rel="stylesheet" href="<?php echo $stylesheets[$pageNumber]; ?>.css" type="text/css">
</head>

<p>This is page six! You will notice that page six is coloured yellow, unlike any of the other pages</p>

Andy123 · November 10, 2012

Also you could try a cookie or session

That's true, and we can add globals to the list as well. However, those are poor solutions. For a small project, I would store an array in a file like Andy-H does in his example. For bigger projects, I would store it in a database and cache it on the web server. For large projects, I would do neither and look into using a framework.

AyKay47 · November 10, 2012

That's true, and we can add globals to the list as well. However, those are poor solutions. For a small project, I would store an array in a file like Andy-H does in his example. For bigger projects, I would store it in a database and cache it on the web server. For large projects, I would do neither and look into using a framework.

Using global is never a valid solution.

Edited November 10, 2012 by AyKay47

Andy123 · November 10, 2012

Using global is never a valid solution.

Using sessions or cookies for this problem is also not a valid solution, hence why I wrote that they are all poor solutions. They can, however, solve the problem - just in a very bad way.

Pikachu2000 · November 10, 2012

icthos, you're already querying the database in functions.php. Is there a reason you wouldn't just store the stylesheet info and query for it at the same time?

PFMaBiSmAd · November 10, 2012

Short answer - programming does not involve magic or the ability to go back in time. You cannot use a variable until after it has been assigned a value.

You are trying to paste together a html document using php include statements for the various sections. That method is inflexible and limited in what it can do.

A solution would be to form your dynamic output in php variables, then at the end of your code, produce the actual html document and echo the various php variables at the appropriate place in the html document. The following is an example of a pagination script that shows this method -

<?php
$title = "Pagination w/css links";
// settings used by this code -
$rows_per_page = 20; // how many rows to display per logical page
$pagination_name = 'pageno'; // the $_GET[xxxxx] index name to use for pagination
$pagination_range = 3; //  maximum number of pagination links to show either side of the currently selected page

// connect to your database server and select your database here...

// assuming this is being used for a search script, output a simple search form and produce a $where_clause to match the rows you are interested in
$search_form = "<form method='get' action=''>Search: <input type='text' name='search'><input type='submit'></form>";

// get and condition any search term
$search = isset($_GET['search']) ? trim($_GET['search']) : '';
$where_clause = '';
if($search != ''){
   // form a simple LIKE '%search term%' comparison
   $where_clause = sprintf("WHERE name LIKE '%s%%'",mysql_real_escape_string($search));
}

// define the main and count queries
$main_query = "SELECT * FROM collages $where_clause";
$count_query = "SELECT COUNT(*) FROM collages $where_clause";

// find the total number of matching rows
$result = mysql_query($count_query) or die("Query failed: $count_query<br />Error: " . mysql_error());
list($total_rows) = mysql_fetch_row($result);

// calculate the total number of logical pages
$total_pages = ceil($total_rows/$rows_per_page);

// get and condition or set a default for the requested page
$requested_page = isset($_GET[$pagination_name]) ? intval($_GET[$pagination_name]) : 1;

// set max/min limits for the requested page. max first, then min so if the total is zero (no matching data), the requested page is 1
if($requested_page > $total_pages){
  $requested_page = $total_pages;
}
if($requested_page < 1){
  $requested_page = 1;
}

// calculate the starting row number for the requested logical page
$offset = ($requested_page - 1) * $rows_per_page;

// form the actual query to retrieve the matching data for the requested logical page
$query = "$main_query LIMIT $offset, $rows_per_page";

// query for the actual data
$result = mysql_query($query) or die("Query failed: $query<br />Error: " . mysql_error());

// get number of rows returned by the query for the logical page
$num_rows = mysql_num_rows($result);
$main_content = '';
if($num_rows == 0){
   // query matched no rows
   $main_content .= "There are no matching records to display on this page.";
} else {
   $main_content .= "Your query matched $total_rows record" .($total_rows > 1 ? 's' : '').". ";
   $main_content .= "Displaying records: ".($offset+1)." - " . ($offset+$num_rows) . ".<br />";
   // loop over the matching rows and output the data the way you want on your page
   while($row = mysql_fetch_assoc($result)){
       $main_content .= $row['name'] . '<br />';
   }
}

// build pagination navigation links (if there's more than one page)
// this code uses http_build_query to build the query string on the end of the URL so that any existing get parameters, such as a search term, are not modified. This code only modifies the pagination get parameter and leaves all other get parameters as is.
$pagination_links = ''; // build pagination links in a string (output it later in your actual content on the page)
if($total_pages > 1){
   // produce 'first' and 'prev' links
   // <li><a href="#" class="prevnext disablelink">« previous</a></li>
   // <li><a href="#" class="prevnext">« previous</a></li>
   if($requested_page > 1){
       // 'first' page link
       $_GET[$pagination_name] = 1; // set/replace the pagination GET parameter (all other GET parameters unchanged)
       $pagination_links .= "<li><a class='prevnext' href='?" . http_build_query($_GET, '', '&') . "'><<</a></li> ";
       // 'prev' page link
       $_GET[$pagination_name] = $requested_page - 1; // set/replace the pagination GET parameter (all other GET parameters unchanged)
       $pagination_links .= "<li><a class='prevnext' href='?" . http_build_query($_GET, '', '&') . "'><</a></li> ";
   } else {
       // text only place holders
       $pagination_links .= "<li><a href='#' class='prevnext disablelink'><<</a></li> ";
       $pagination_links .= "<li><a href='#' class='prevnext disablelink'><</a></li> ";
   }

   // loop to produce links for a range of pages around the currently selected page
   for($x = $requested_page - $pagination_range; $x < $requested_page + $pagination_range + 1; $x++){
       // if between min and max page number
       if($x > 0 && $x <= $total_pages){
           // if currently requested page, output text only place holder
           if($x == $requested_page){
               //<li><a href="#" class="currentpage">1</a></li>
               $pagination_links .= "<li><a href='#' class='currentpage'>$x</a></li> ";
           } else {
               // output page link
               $_GET[$pagination_name] = $x; // set/replace the pagination GET parameter (all other GET parameters unchanged)
               $pagination_links .= "<li><a href='?" . http_build_query($_GET, '', '&') . "'>$x</a></li> ";
           }
       }
   }

   // produce 'next' and 'last' links
   if($requested_page != $total_pages){
       // 'next' page link
       $_GET[$pagination_name] = $requested_page + 1; // set/replace the pagination GET parameter (all other GET parameters unchanged)
       $pagination_links .= "<li><a class='prevnext' href='?" . http_build_query($_GET, '', '&') . "'>></a></li> ";
       // 'last' page link
       $_GET[$pagination_name] = $total_pages; // set/replace the pagination GET parameter (all other GET parameters unchanged)
       $pagination_links .= "<li><a class='prevnext' href='?" . http_build_query($_GET, '', '&') . "'>>></a></li>";
   } else {
       // text only place holders
       $pagination_links .= "<li><a href='#' class='prevnext disablelink'>></a></li> ";
       $pagination_links .= "<li><a href='#' class='prevnext disablelink'>>></a></li>";
   }
}
?>
<html>
<head>
<title><?php echo $title; ?></title>
<style type="text/css">

.pagination{
padding: 2px;
}

.pagination ul{
margin: 0;
padding: 0;
text-align: left; /*Set to "right" to right align pagination */
font-size: 16px;
}

.pagination li{
list-style-type: none;
display: inline;
padding-bottom: 1px;
}

.pagination a, .pagination a:visited{
padding: 0 5px;
border: 1px solid #9aafe5;
text-decoration: none;
color: #2e6ab1;
}

.pagination a:hover, .pagination a:active{
border: 1px solid #2b66a5;
color: #000;
background-color: #FFFF80;
}

.pagination a.currentpage{
background-color: #2e6ab1;
color: #FFF !important;
border-color: #2b66a5;
font-weight: bold;
cursor: default;
}

.pagination a.disablelink, .pagination a.disablelink:hover{
background-color: white;
cursor: default;
color: #929292;
border-color: #929292;
font-weight: normal !important;
}

.pagination a.prevnext{
font-weight: bold;
}

</style>
<body>
<div><?php echo $search_form; ?></div>
<div class="pagination">
   <ul>
       <?php echo $pagination_links; // echo the links wherever you want in the content on your page ?>
   </ul>
</div>
<div><?php echo $main_content; ?></div>
</body>
</html>

Sign In

Can You Echo A $Var That Is Defined Later On In The Script?

Recommended Posts

icthos

Link to comment

Share on other sites

MDCode

Link to comment

Share on other sites

Andy123

Link to comment

Share on other sites

floridaflatlander

Link to comment

Share on other sites

MDCode

Link to comment

Share on other sites

Andy-H

Link to comment

Share on other sites

Andy123

Link to comment

Share on other sites

AyKay47

Link to comment

Share on other sites

Andy123

Link to comment

Share on other sites

Pikachu2000

Link to comment

Share on other sites

PFMaBiSmAd

Link to comment

Share on other sites

Join the conversation

Browse

Activity

Important Information