Auto-Completion in Unix VI editor

After using graphical IDE's like Visual Studio, I'm used to pressing CTRL+Space to auto-complete a variable or function name. Now, I开发者_StackOverflow社区 know such a thing isn't completely possible in VI, but I heard there was a list of commands that could be mapped that allowed automatic completion of variables and functions in the current file opened. Does anyone know what this sequence is?

Just noticed that you said "vi"; I hope that "vim" is also okay.

It depends on the particular programming language, but in general, the magic word is Omnicomplete.

Put this into .vimrc:

filetype plugin on
set ofu=syntaxcomplete#Complete

Press Ctrl+N or Ctrl+P to trigger the completion. This is insanely customizable; you might like the tips here that make it work more like other IDEs.