By default, source code of any programming language didn't highlight syntax in your post. Fortunately, so much plugin for wordpress could solve this issue.
1. Code markup: http://www.thunderguy.com/semicolon/wordpress/code-markup-wordpress-plugin/
2. WP Advanced Code Editor.: http://www.techlyzer.com/wp-advanced-code-editor/
3. Developer Formatter : http://wordpress.org/extend/plugins/devformatter/
4. File Inliner : http://www.idiap.ch/~pabbet/personal-projects/wordpress-file-inliner-plugin/
5. FV Code Highlighter: http://www.frank-verhoeven.com/wordpress-plugin-fv-code-highlighter/