Renaming variables

Question

What is the simplest way to rename variables in Vim, without adding any new packages? Is there a way without using regexps, too?

Answer 1

Place cursor at name to rename and type

gd (or gD if you're renaming a global variable).

gd         Goto local Declaration.  When the cursor is on a local
            variable, this command will jump to its declaration.
            First Vim searches for the start of the current
            function, just like "[[".  If it is not found the
            search stops in line 1.  If it is found, Vim goes back
            until a blank line is found.  From this position Vim
            searches for the keyword under the cursor, like with
            "*", but lines that look like a comment are ignored
            (see 'comments' option).
            Note that this is not guaranteed to work, Vim does not
            really check the syntax, it only searches for a match
            with the keyword.  If included files also need to be
            searched use the commands listed in |include-search|.
            After this command |n| searches forward for the next
            match (not backward).
            {not in Vi}

gD          Goto global Declaration.  When the cursor is on a
            global variable that is defined in the file, this
            command will jump to its declaration.  This works just
            like "gd", except that the search for the keyword
            always starts in line 1.  {not in Vi}

Then

c (change) + gn new_name esc

gn         Search forward for the last used search pattern, like
            with `n`, and start Visual mode to select the match.
            If the cursor is on the match, visually selects it.
            If an operator is pending, operates on the match.
            E.g., "dgn" deletes the text of the next match.
            If Visual mode is active, extends the selection
            until the end of the next match.

and

. (repeat) one or more times to rename next occurrence(s)

or

:%norm . to rename all occurrences in the buffer at once.