gtk:text-iter-offset (iter)

iter -- a gtk:text-iter instance
offset -- an integer with a character offset

The gtk:text-iter-offset function returns the character offset of an iterator. The (setf gtk:text-iter-offset) function sets the iterator to point to the given character offset.

Each character in a text buffer has an offset, starting with 0 for the first character in the text buffer. Use the gtk:text-buffer-iter-at-offset function to convert an character offset back into an iterator.