GNU bug report logs - #59531
29.0.50: An alternative to `string-to-number` which throws an error (or returns a NIL value) when input is non-parseable as number

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From: Jean Louis <bugs <at> gnu.support>
To: Robert Pluim <rpluim <at> gmail.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>, 59531 <at> debbugs.gnu.org, Ramesh Nedunchezian <rameshnedunchezian <at> outlook.com>
Subject: bug#59531: 29.0.50: An alternative to `string-to-number` which throws an error (or returns a NIL value) when input is non-parseable as number
Date: Fri, 16 Dec 2022 09:28:14 +0300

(defun string-is-number-p (s)
  "Return number only if string is actual number, otherwise NIL."
  (let* ((s (string-trim s)))
    (cond ((seq-empty-p s) nil)
	  ((string-match "[^0123456789\\.-]" s) nil)
	  ((string-match "-" s 1) nil)
	  ((numberp (string-to-number s)) (string-to-number s)))))


I use this function to make sure string is number and it
returns either the number of nil, and function is not
exhaustive.


Jean

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