The TAB key in emacs is bound to indent-for-tab-command, but the indent itself converts all the tabs into spaces, which I didn't like because it's harder to locate character in the code and the code gets bigger.
I tried to use (setq-default indent-tabs-mode t), (setq tab-width 4) or (setq default-tab-width 4), none of the above works. Neither the width of \t character changes, nor the indent uses tabs instead of spaces. And 'M-x tabify' does not work either.
I searched for a long time but got nearly nothing. Any ideas?