Displaying source code in your WordPress posts is extremely simple, you can add a <code> tag around your code and it will be displayed in your blog post.
The problem with the <code> tag in WordPress
As pointed out in Writing Code in Your Posts from the WordPress Codex, a few issues can arise from using this method if you are not careful. Using the <code> tag doesn’t tell WordPress to strip the HTML references from the post.
The Solution to displaying code in WordPress
Simply using the following shortcode structure, your code snippets can be displayed elegantly in your post.
You can see a better example SyntaxHighlighter Evolved plugin use on our post –