StringCombine - Cookbook - s c h e m a t i c s : c o o k b o o k

Combining Strings

Problem

You need to combine several strings into a larger string.

Solution

The R5RS function string-append is the de-facto answer here:

> (string-append "Some " "text " "and" " stuff")
"Some text and stuff"

string-append will always allocate a new string. SRFI-13 defines string-append/shared which is allowed to share storage with its parameters. Also, if you have a list of strings you want to combine, SRFI-13 defines string-concatenate and string-concatenate/shared, which looks like this:

>(string-concatenate '("Some " "text " "and" " stuff"))
"Some text and stuff"

Discussion

The /shared variants bear some discussion. In the examples above, /shared will never reuse a buffer because we're using string literals. Well almost never. /shared may reuse a buffer in the case where you give it a single argument:

>(define t1 "Some String")
> (eq? (string-append/shared t1 ) t1)
#t
> (eq? (string-concatenate/shared (list t1) ) t1)
#t

(define t1 (make-string 0))

-- GordonWeakliem - 06 Apr 2004

CookbookForm
TopicType:	Recipe
ParentTopic:	StringRecipes
TopicOrder:	150

Current Rev: r1.4 - 09 Jun 2004 - 15:42 GMT - NoelWelsh, Revision History:Diffs | r1.4 | > | r1.3 | > | r1.2

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