Get the amount of indent for line {lnum} according the C indenting rules, as with 'cindent'. The indent is counted in spaces, the value of 'tabstop' is relevant. {lnum} is used just like in |getline()|. When {lnum} is invalid or Vim was not compiled the |+cindent| feature, -1 is returned. See |C-indenting|. Can also be used as a |method|: GetLnum()->cindent()