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Folding functions with the prototype included

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created August 2, 2003 · complexity intermediate · author Matt Perry · version 6.0

The built-in syntax based folding of C/C++ files is good enough for most users, but it will only fold functions from the "{" to the "}". A user may want to fold the prototype as well. Using foldexpr allows this.

function FoldBrace()
  if getline(v:lnum+1)[0] == '{'
    return '>1'
  if getline(v:lnum)[0] == '}'
    return '<1'
  return foldlevel(v:lnum-1)
set foldexpr=FoldBrace()
set foldmethod=expr

Note that this will only work if you put the braces on lines by themselves in the very first column, for example:

  void func()



  • Merge in comments below, it looks like there's an improved version of the script, should test
  • Address some shortcomings? This is actually a very difficult problem, Perl syntax tries to do it and fails.
  • Maybe use the syntax items in the fold expression for help

Johannes Zellner started to define a fold(ing?) plugin for C and C++. I've tried to enhanced it a little, but unfortunately, it is still imperfect.


--Luc Hermitte 13:39, 7 June 2007 (UTC), August 2, 2003 18:34

That certainly is more featureful than my version. But I prefer to use foldnestmax=1 - I find it annoying to have more than 1 fold level.

I've modified my fold function to work if the { is on the same line as the function, ie:

void bla() {

I'd like to be able to use v:foldstart in my fold function so I can check that the } has the same indent as the line containing the {. That way I could match braces that aren't in the first column. But this is good enough for my purposes.

function FoldBrace()
  if getline(v:lnum+1)[0] == '{'
    return 1
  if getline(v:lnum) =~ '{'
    return 1
  if getline(v:lnum)[0] =~ '}'
    return '<1'
  return -1

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