PHP powered banner rotator using the power of flat files (txt files).
This week we will build a simple banner/image rotator. We will be doing this using flat files (txt files) and a couple of file functions in php.
Here is what the banner txt file should look like, you simply just put one image/link pair per line. The "[$]" seperator is used to split apart the img/link pairs. We use this interesting seperator to ensure it is not going to be contained in the link or image reference.
google.gif[$]http://www.google.com
friendster.gif[$]http://www.friendster.com
yahoo.gif[$]http://www.yahoo.com
First off, define the variables for this project
//// Customizable Settings for banner script//$banner_txt_file = 'my_banners.txt'; // Our txt file of banner references$banner_links = true; // Show banner as just image or with link (href)Now lets set up a function to contain all of our banner code and make it easier to call in the future.
<?
function display_banner() {
// use 'global' to reference our preset variables
global $banner_txt_file, $banner_links ;
mt_srand((double)microtime() * 100000);
$banners = file($banner_txt_file);
$count = count($banners);
$random = rand(0, $count - 1);
$banner = $banners[$random];
$banner_parts = explode("[$]", $banner);
$banner_img = $banner_parts[0];
$banner_link = $banner_parts[1];
$banner_html = "<img src=\"" . $banner_img . "\" />";
// build img tag
if($banner_links)
{ $banner_html = "<a href=\"" . $banner_link . "\">" . $banner_html . "</a>";
}
return $banner_html;
// return the html code
}
?>Now let's take a moment to explain what is happening in those last few lines. First off we define a few global variables to gain access to them in the function (scope issue).
Then we use
mt_srand() to create a random seed, and ultimately allow us to pick a random banner image. Now we begin the file opening process and start reading in our banners and links. We then take these lines of link/img pairs and choose a random one to display. Finally we build our necessary html to display the banner and add the link info if
$banner_links is set to true.
Note: Make sure you "chmod" the banner txt file, so it can actually be read.
To display a random banner, you simply place this PHP code somewhere in your file
print display_banner();Thats it, you now have a working php banner script... next time we will create a feature packed version with MySQL, counters and all sorts of goodies.
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