Vim tab and 4 spaces

After adding the following code to the. VIMRC, restart Vim to create 4 spaces by pressing TAB:
Set ts=4 (Note: TS is the abbreviation for TabStop, set tab width 4 spaces)
Set Expandtab

For a saved file, you can use the following method to replace the Space and tab:
tab is replaced with a space:
: Set ts=4
: Set Expandtab
:%retab!

Space is replaced with tab:
: Set ts=4
: Set Noexpandtab
:%retab!

Add! is the tab that is used to process non-whitespace characters, that is, all tabs, if not added, only the tab at the beginning of the line is processed.

Vim tab and 4 spaces