how to get plugin url in wordpress site

I am new in wordpress, doing a plug in for word press site. Here is a problem with me开发者_如何学JAVA, i want to get plug in url with my plug in name dynamically.That is url like "sitename/wp-content/plugins/plug in name".Here plugin name should be dynamic

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to get plugin base name plugin_basename(__FILE__)

refer here http://codex.wordpress.org/Function_Reference/plugin_basename