commonlisp | Functions | with-output-to-string

with-output-to-string

External Link: Macro WITH-OUTPUT-TO-STRING.

The macro WITH-OUTPUT-TO-STRING can be used to create a string output stream, and return the resulting string at the end.

with-output-to-string (var &optional string-form &key element-type)
declaration* form*

=> result*

element-type specifier is defaulted to character.
form* is implicit progn

with-output-to-string creates a character output stream and performs a series of operation that output to the result. automatically closed on exit side effect: the string is modified

(with-output-to-string (str)
  (write-line "Foobar!" str)
  (write-string "Barfoo!" str))
;=> "Foobar!
;   Barfoo!"

(let ((str (make-string-output-stream)))
  (write-line "Foobar!" str)
  (write-string "Barfoo!" str)
  (get-output-stream-string str))