+
+(defun concatenate-two (string1 string2)
+ (let* ((len1 (length string1))
+ (len2 (length string2))
+ (string (make-array (+ len1 len2) :element-type 'character))
+ (i 0))
+ (dotimes (j len1)
+ (aset string i (char string1 j))
+ (incf i))
+ (dotimes (j len2)
+ (aset string i (char string2 j))
+ (incf i))
+ string))