Question

I’m trying to insert in a buffer the length of a lisp list as follows:

(insert "The list has " (length my-list) " elements")

However this produces a strange not printable character instead of the number of elements, so the result is something like

The list has ^A elements

Do I have to convert the return value? The list is not empty.

Answer 1

You need the format function.

(insert (format "The list has %d elements" (length my-list)))

Alternatively, in this case, you can convert the integer to a string:

(insert "The list has " (number-to-string (length my-list)) " elements")

Control-A is ASCII code 1. Apparently your list had one element when you tried.