PHP Smilies System Tutorial

We'll now start creating the function that converts a plain text into a html text with smiley images in it ( replacing the smilies in the text by their images ). The function will need 2 arguments: the text (string) to replace smilies into and an array of all smilies and corresponding image files. Then all the function has to do is use str_replace to replace the smilies by their images. The array of all smilies to replace will be set up like this:

$smilies = array("smiley" => "image_file");

The keys of the array containing all smilies and the values of the array containing all filenames of the corresponding smiley images. So all our function needs to do is replace the array keys (=smiley text icons) by the html image created out of the array values (=smiley images). However there should be given a directory for all smilies ( which we'll set inside our config file (later) as $smilies_directory ). The path to the image for a smiley will be the smilies_directory / array values of $smilies (=filenames of images). But we don't want the smilies to be replaced by the paths of the images, but by the actual images. So we'll use the html img tag to do so, we do need to use the function array_map to convert each value of the array of images to the format <img src="smilies_directory/array value" /> where array value will be each value of the array ( all filenames of the smilies that need to be replaced ) and smilies_directory is the config variable $smilies_directory. To do this for each value of the array of smilies, we use the array_map function and create_function function to make a function that does this for all values of the array.

function replaceSmilies($str, $smilies) {

//make the config variable $smilies_directory global so that we can use it within this function even though it's defined outside of it
global $smilies_directory;

$icons = array_keys($smilies);
$images = array_map(create_function('$filename', 'global $smilies_directory; return "<img src=\"{$smilies_directory}/{$filename}\" />";'), array_values($smilies));

$new_str = str_replace($icons, $images, $str);

return($new_str);
}

We'll also create a standard array of smilies that will be automaticly used within the function when no other array ($smilies) is provided:

<?php

function replaceSmilies($str, $smilies = NULL) {

global $smilies_directory;

if(is_null($smilies)) {
global $default_smilies;
$smilies = $default_smilies;
}

$icons = array_keys($smilies);
$images = array_map(create_function('$filename', 'global $smilies_directory; return "<img src="\"{$smilies_directory}/{$filename}\"" />";'), array_values($smilies));

$new_str = str_replace($icons, $images, $str);

return($new_str);

}

?>

This way it will automaticly use the default smilies set/array ( which we'll create in a config file next) when no alternative smilies set is provided to the function.

Save the function inside of a file functions.php.

The config file is pretty simple: it basicly needs one array of smilies ( the default smilies set to use ) and the directory of the smilies images. For example:

config.php

<?php

$default_smilies = array(
":)" => "smile.gif",
":(" => "mad.gif",
":P" => "tongue.gif",
";)" => "wink.gif",
":D" => "biggrin.gif",
":/" => "frown.gif",
"o.O" => "eek.gif",
":?" => "confused.gif",
":cool:" => "cool.gif",
":rolleyes:" => "rolleyes.gif",
":redface:" => "redface.gif"
);

$smilies_directory = "images/smilies"; //the directory in which the images of the smilies are put

?>

Note: the smiley set used can be found here.

To use our script we need to include the config file and the functions file into our PHP webpage and then we can simply call our function to replace smilies in any string.

<?php

include_once("config.php");
include_once("functions.php");

$string = "Hey there :D This is an example text :) Only a few smilies in this text but just an example ;).";

echo replaceSmilies($string);

?>