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r6rs-lib
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<a name="node_chap_18"></a>
<h1 class=chapter>
<div class=chapterheading><a href="r6rs-lib-Z-H-1.html#node_toc_node_chap_18">Chapter 18</a></div><br>
<a href="r6rs-lib-Z-H-1.html#node_toc_node_chap_18">Mutable strings</a></h1>
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<p>
The <tt>string-set!</tt> procedure provided by the <tt>(rnrs mutable-strings (6))</tt><a name="node_idx_1278"></a>library allows mutating the characters of a string in-place.</p>
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<div align=left><tt>(<a name="node_idx_1280"></a>string-set!<i> string k char</i>)</tt> procedure </div>
<p>
</p>
<p class=noindent><em>K</em> must be a valid index of <i>string</i>.
The <tt>string-set!</tt> procedure stores <i>char</i> in element </p>
<p class=noindent><em>k</em> of <i>string</i>
and returns unspecified values. </p>
<p>
Passing an immutable string to <tt>string-set!</tt> should cause an exception
with condition type <tt>&assertion</tt> to be raised.
</p>
<tt>(define (f) (make-string 3 <tt>#</tt><tt>\</tt>*))<br>
(define (g) "***")<br>
(string-set! (f) 0 <tt>#</tt><tt>\</tt>?) ⇒ <em>unspecified</em><br>
(string-set! (g) 0 <tt>#</tt><tt>\</tt>?) ⇒ <i>unspecified</i><br>
; should raise <tt> &assertion</tt> <i>exception</i><br>
(string-set! (symbol->string ’immutable)<br>
0<br>
<tt>#</tt><tt>\</tt>?) ⇒ <i>unspecified</i><br>
; should raise <tt> &assertion</tt> <i>exception</i><p></tt></p>
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</p>
<blockquote><em>Note: </em>
Implementors should make <tt>string-set!</tt> run in constant
time.
</blockquote>
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<div align=left><tt>(<a name="node_idx_1282"></a>string-fill!<i> string char</i>)</tt> procedure </div>
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Stores <i>char</i> in every element of the given <i>string</i> and returns unspecified values. </p>
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