String append: Difference between revisions

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 =={{header|Emacs Lisp}}==
-===version 1===
+While strings in Emacs Lisp are mutable, they're fixed size. Therefore the <code>concat</code> function creates a new string and the existing string must be referenced twice:
-<lang Emacs Lisp>
-(defun glue (str1 str2)
+<lang Lisp>(defvar str "foo")
-  (concat str1 str2) )
+(setq str (concat str "bar"))
-</lang>
+str ;=> "foobar"</lang>
-===version 2===
-<lang Emacs Lisp>
+Buffers can be thought of as expandable strings:
-(defun glue (str1 str2)
-  (format "%s%s" str1 str2) )
+<lang Lisp>(let ((buf (get-buffer-create "*foo*")))
-</lang>
+  (with-current-buffer buf
-<b>Eval:</b>
+    (insert "foo"))
-<lang Emacs Lisp>
+  (with-current-buffer buf
-(setq str "Hello, ")
+    (goto-char (point-max))
-(setq str (glue str "World!") )
-(insert str)
+    (insert "bar")
+    (buffer-string)))
-</lang>
+;; => "foobar"</lisp>
-<b>Output:</b>
-<pre>
-Hello, World!
-</pre>
 =={{header|Erlang}}==