How Do I Color-Highlight PHP Source Codes

If you’ve been a regular reader of this blog you might have wondered
how I highlight PHP code using different colors. Your prompt answer would be,
using some software. Well not exactly as PHP has built-in feature for highlighting
source code. And of course I use that.

Here are some of the different methods that you can use to highlight PHP source
code, you may use any one of them depending upon what your intended purpose
is.

1. If have set-up PHP as explained in Configuring
Apache Web Server and PHP then you can just name your PHP files like
“filename.phps” to tell PHP to highlight and show the file upon
request and not execute it. You can use this method when you want to link the
highlighted source from some web page. You cannot, however, embed source code
into web pages using this method.

PHP Source Code Highlighting - Using .phps Files

2. You can use the following function to highlight any
PHP (.php) script file:

highlight_file('filename.php');

You just have to pass the filename to this function and PHP will highlight
and output the code to the browser.

Main benefit with this is you can embed source code into your web pages wherever
you want.

e.g.:

<?php echo "<h1>Blah Blah Blog</h1>"; echo "<h2>Highlighting PHP Source Code</h2>"; echo "<p>blah blah blah!!</p>"; echo "<p>Write anything you want and embed source code (highlighted)</p>"; echo "<p>Embedded source code is listed below:</p>"; highlight_file('highlight_file.php'); ?>

PHP Source Code Highlighting - Using highlight_file() Function

3. There are times when you just want to highlight a
single line of code which can be done using:

highlight_file('string here');

It could be used when you have lost of unrelated lines of code to highlight.
In other words, when the codes are not together but are sprinkled throughout
the page. For this you don’t have to create any files to be highlighted,
just use this function with thee source code string.

e.g.:


<?php



echo "<h1>Blah Blah Blog</h1>";

echo "<h2>Highlighting PHP Source Code</h2>";



echo "<p>First String: <br />";

highlight_string("<?php echo \"<h1>Blah Blah Blog</h1>\"; ?>");



echo "<br />Second String: <br />";

highlight_string("<?php foreach($keywords as $keyword) ?>");



echo "</p><p>blah blah blah blah <br />blah blah blah</p>";

echo "<p>Third highlighted String: <br />";

highlight_string("<?php if(isset($s)) ?>");



echo "<p>Notice how many unrelated code strings are here. The best way to format them in this condition is to use ";

highlight_string("<?php highlight_string(\"string\"); ?>");

echo "function </p>";



?>

Which would show up like below:

PHP Source Code Highlighting - Using highlight_string() Function

One interesting thing that you can play with, regarding syntax highlighting
is the “php.ini” file. Look for these lines in that file:

; Colors for Syntax Highlighting mode. Anything that's acceptable in ; <span style="color: ???????"> would work. highlight.string = #DD0000 highlight.comment = #FF9900 highlight.keyword = #007700 highlight.bg = #FFFFFF highlight.default = #0000BB highlight.html = #000000

Here, as you can see, the colors for highlighting different parts of the code
are defined. You can change these to alter the colors that are use for highlighting.
Colors are in HEX RGB format (same as HTML color code).

NOTE: If you don’t seem to be able to see the source
code highlighted you might need remove the ";" (semi-colons) from
the starting of each of the "highlight." line so it looks like the
above code:

; Colors for Syntax Highlighting mode. Anything that's acceptable in ; <span style="color: ???????"> would work. ;highlight.string = #DD0000 ;highlight.comment = #FF9900 ;highlight.keyword = #007700 ;highlight.bg = #FFFFFF ;highlight.default = #0000BB ;highlight.html = #000000