How do I quickly switch between the current file and the last edited file?

Explanation

Pressing <C-^> (Ctrl-6 on most keyboards) instantly toggles between the current buffer and the alternate file — the last file you were editing. This is Vim's fastest file-switching mechanism, requiring zero thought about buffer numbers or file names.

How it works

• Vim tracks the "alternate file" in the # register — it's the buffer you were in immediately before the current one
• <C-^> swaps the current buffer with the alternate buffer
• Pressing it again swaps back, creating a rapid toggle between two files
• The Ex command equivalent is :e # or :b #

Example

You're editing main.go and you open utils.go with :e utils.go. Now:

• Current file: utils.go
• Alternate file: main.go

Press <C-^> to jump back to main.go. Press <C-^> again to return to utils.go. You can bounce between them endlessly.

This is shown in :ls output — the % marks the current buffer, # marks the alternate:

  1 #    "main.go"           line 42
  2 %a   "utils.go"          line 7

Tips

• Use {count}<C-^> to switch to a specific buffer number: 3<C-^> switches to buffer 3
• If you get E23: No alternate file, it means you haven't visited a second file yet in this session
• The alternate file is per-window, so each split maintains its own alternate
• Combine with splits: <C-w><C-^> opens the alternate file in a horizontal split
• This is especially powerful during development when you're bouncing between a source file and its test file, or between a header and implementation
• Map it to something easier if <C-^> feels awkward: nnoremap <leader><leader> <C-^>