This is a highlight plugin for the blogging platform WordPress.
Plugin archive: Highlight source package
The plugin code is saved in the examples subdirectory.
Paste the following in the code section of the blog editing form:
<pre lang="c">#include <stdio.h>
int main (void){
printf("This is some random code");
return 0;
}</pre>
Use the lang parameter to define the programming language (c, php, py, xml, etc). See the highlight documentation to learn all possible languages.
See the highlight.php file for some formatting options (line numbering, code indentation, line wrapping etc).