The test for a loop with an incrementing counter can be an expression
such as (< count desired-number) which returns t for
true if the value of count is less than the
desired-number of repetitions and nil for false if the
value of count is equal to or is greater than the
desired-number. The expression that increments the count can
be a simple setq such as (setq count (1+ count)), where
1+ is a built-in function in Emacs Lisp that adds 1 to its
argument. (The expression (1+ count) has the same result
as (+ count 1), but is easier for a human to read.)
The template for a while loop controlled by an incrementing
counter looks like this:
set-count-to-initial-value (while (< count desired-number) ; true-or-false-test body… (setq count (1+ count))) ; incrementer
Note that you need to set the initial value of count; usually it
is set to 1.