Highlight PHP Codes with Line Numbers Using highlight_file () Function

PHP has an awesome function that highlights its own code, means you can highlight PHP codes using a function which is the PHP highlight_string () for string and highlight_file () for a PHP file.

On using this function, the highlighted code never come with line numbers but in this post I’ll show you how I tweak up the function to have line numbers for it. I don’t like code copiers like just copy the codes and get what you want, I will show you step by step on how I achieved this. 🙂

Now in the case am using the highlight_file () function, and also am using the help of the client side to beautify the highlighter and the line numbers. I guess you’ve already added the <html><head>… elements, for the server side comments are in the code below which should be self explanatory 🙂

<title>Syntax Highlighter</title>
<style type="text/css">
.syntax-highlight-line {
color: #000000;
font-size: 12px;
float: left;
font-family: 'Source Code Pro';
padding-right: 5px;
.syntax-highlight-code {
padding-left: 30px;
font-family: 'Source Code Pro';
border-bottom: 1px solid #EEEEEE;

//highlighting file and second argument set to true for this function to return the value instead of echoing it
$file = highlight_file ( 'shit.php', true );

//does the file really exist?
if ( !$file ) {
die ( 'Empty file to highlight' );
//Oh ye, it does
else {

//since the output is returned as html and new lines are broken with the <br /> tag, let's explode each line to array using <br /> to recognise a new line
$file = explode ( '<br />', $file );

//first line number should be 1 right?
$i = 1;

//Now for each line we are gonna add line number to it and wrap it up with their divs
foreach ( $file as $line ) {
echo '<div class="syntax-highlight-line">' . $i . '. </div> <div class="syntax-highlight-code">' . $line . '</div><br/>';

//Oh, line number should keep incrementing as long as new line of code still exists

//that's it

The above should output something like the picture below, goodluck 🙂