How to set the default indentation width globally?

Question

By default Emacs uses tab instead of spaces for indentation, so I changed these 2 variables to change this behavior,

  (setq-default indent-tabs-mode nil)        ;; Disable indent with tabs
  (setq default-tab-width 4)                 ;; Set default indent width

It did change the indent mode from tab to space, but if I press RET, when I am in a programming buffer C++ for example, to enter a new line, I get 2 spaces of indentation instead of 4. How do I set this indentation level to 4 be default globally.

Also when when I am editing a line for example, it auto shift the line back to 2 space of indentation, for some reason, and also re-formats how I wrote the code, for example, I usually write like this,

if (true)
{
    // 4 spaces for indentation.
}

If I try to edit or add something, it pushes the lines back to 2 spaces of indentation and also sometimes re-formats the brackets position,

if (true) {
  // 2 spaces for indentation.
}

I am constantly fighting with this thing, and it gets annoying very quickly sometimes. As far as I know, I did not install any formatting package.

Answer 1

There is no global setting for the indentation width. Instead, each mode has it’s own setting. In c-mode it is called c-basic-offset. In js2-mode it is js2-basic-offset. For lisp-mode there are two: lisp-body-indent and lisp-indent-offset.

You’re probably using c-mode for editing your C++ files, so you should customize the c-basic-offset variable. Run M-x customize-variable then enter the variable name that you would like to change.