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How do I find the length of a number?

4 posts · 4333 views

joeish80829

#1 Wed May 28, 2014 9:08 am

is there anyway to find the length of a number e.g.

 (length 1234567890)

would equal 10, or:

(length 5487)

would equal 4

Goheeca

#2 Wed May 28, 2014 9:33 am

Re: How do I find the length of a number?

Mathematical way:

(defun number-length (num)
  (if (zerop num)
      1
      (1+ (floor (log num 10)))))

or text-representation-way:

(defun number-length (num)
  (length (format nil "~s" num)))

cl-2dsyntax is my attempt to create a Python-like reader. My mirror of CLHS (and the dark themed version). Temporary mirrors of aferomentioned: CLHS and a dark version.

joeish80829

#3 Wed May 28, 2014 1:51 pm

Re: How do I find the length of a number?

Thanks a lot! That is just what I was looking for. I really do appreciate all these great answers you have given me.

marcoxa

#4 Fri May 30, 2014 12:51 pm

Re: How do I find the length of a number?

Define "length of a number". For INTEGERs it is one thing, for floating point numbers not so easy.

In any case, you have INTEGER-LENGTH in ANSI, which may or may not be of use.

Marco Antoniotti