Emacs: gethash does not see key in hashtable

Question

I appreciated the following elisp code in ielm:

(setq foo-hash (make-hash-table))

(puthash "location" "house" foo-hash)

(defun foo-start ()
  (interactive)
  (message (gethash "location" foo-hash)))

However, when I start (foo-start)or (gethash "location" foo-hash), I only get an nilecho. Entering foo-hashielm echoes only:#s(hash-table size 65 test eql rehash-size 1.5 rehash-threshold 0.8 data ("location" "house"))

Is this a mistake or am I doing something wrong?

Emacs Version: 24.0.95.1

Answer 1

Elisp hash tables are used eqlfor comparison by default. Lines will not be equal to c eqlif they are not the same object. You probably want to use equalone that compares the contents of strings. Create your hash table with this:

(make-hash-table :test 'equal)