Code completion for gedit

Is there any code completion plugin for gedit which supports all common programming lanuages (especially C and HTML/CSS)?

Snippets plug-in for gedit

gedit has more plug-ins than I can remember but one of them is called snippets and it is very popular.

Supported languages

I do most of my coding in bash but c is also supported along with dozens of other languages including HTML and CSS which are also on your shopping list.

Installation of gedit plug-ins and the snippets one in particular is straight forward.

Review the default auto-completion options from the top menu by selecting Tools -> Manage Snippets...:

You can add many more auto-complete options and even assign them shortcut keys.

Auto-completion using Tab key

When using bash I almost always forget the syntax for certain commands. One of them is the for loop with C-like syntax option. In this GIF animation why type the letters for followed by the Tab key for auto complete:

There are other gedit plug-ins active in the GIF animation above. The bottom of the screen is the external terminal interface where you can type shell commands. The right hand slide is the thumbnail slider. The grey area in between warns you when your typing is longer than 80 characters, or whatever size you choose.

Tool Output at the very bottom means external tools is enabled. This allows you to launch commands via hot keys and see the output. Handy if for example you want to pass your file to a LINT checker or compiler.