How to expand tab into spaces in vi / vim
It is always good to use spaces instead of tab when editing program's source code.
In you ~/.vimrc, add the following lines
: set expandtab
: set shiftwidth=4
: set softtabstop=4
: set tabstop=4
Only expandtab is needed in fact, but most opensource projects tend to maintain a consistency of 4-spaces-indent, follow it anyway.