I changed my Emacs configuration including indentation settings -now when I open an old C++ file I can write code and it looks like this:

int x(int z){
    return z;

However, the old code in this file looks like this:

int x(int z){
        return z;

In other words its indentation is doubled. How can I reformat the old code so that it's appropriately indented?

1 Answer 1


In short: C-x h and then TAB

It changes formatting for whole buffer.


  • C-x h - marks whole buffer
  • TAB - indent marked region

So, effectively we mark all, then indent ;-)

  • Could you please edit your post to describe what command C-x h TAB runs, and how it resolves OP's problem? It's for the benefit of future readers who may have the same problem.
    – Dan
    Apr 11, 2017 at 23:42
  • C-x h marks whole buffer and TAB runs c-indent-line-or-region for me.
    – Alex
    Apr 12, 2017 at 9:37

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