Re: How to count the number of occurrences of a character in a string?

[Eli Zaretskii <eliz@gnu.org>]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Tue, 13 Oct 2015 12:06:36 -0400
> Cc: Help Gnu Emacs mailing list <help-gnu-emacs@gnu.org>
> 
> (progn
>   (defun my/count-char-in-string (char str)
>     "Count the number of times CHAR character appears in STR string."
>     (message "\n==========\nstr = %0s" str)
>     (let* ((num-matches 0)
>            (ptr 0) ; initiate pointer for string match
>            match-pos)
>       (while (<= ptr (length str))
>         (message "ptr = %0d" ptr)
>         (setq match-pos (string-match-p
>                          (regexp-quote (char-to-string char)) str ptr))
>         (if match-pos
>             (progn
>               (setq ptr (1+ match-pos))
>               (message "match-pos = %0d ptr = %0d" match-pos ptr)
>               (setq num-matches (1+ num-matches)))
>           (progn
>             (setq ptr (1+ ptr)))))
>       (message "%0d occurrence%0s of `%c' char found in \"%s\"."
>                num-matches (if (/= 1 num-matches) "s" "") char str)
>       num-matches))

Isn't the following simpler?

  (let ((str-list (append str nil))
        (num-matches 0))
    (while str-list
      (if (= (car str-list) char)
          (setq num-matches (1+ num-matches)))
      (setq str-list (cdr str-list)))
      num-matches)