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class="tocviewlink" data-pltdoc="x">Characters</a></td></tr><tr><td align="right">3.4 </td><td><a href="strings.html" class="tocviewlink" data-pltdoc="x">Strings (Unicode)</a></td></tr><tr><td align="right">3.5 </td><td><a href="bytestrings.html" class="tocviewlink" data-pltdoc="x">Bytes and Byte Strings</a></td></tr><tr><td align="right">3.6 </td><td><a href="symbols.html" class="tocviewlink" data-pltdoc="x">Symbols</a></td></tr><tr><td align="right">3.7 </td><td><a href="keywords.html" class="tocviewlink" data-pltdoc="x">Keywords</a></td></tr><tr><td align="right">3.8 </td><td><a href="pairs.html" class="tocviewlink" data-pltdoc="x">Pairs and Lists</a></td></tr><tr><td align="right">3.9 </td><td><a href="vectors.html" class="tocviewlink" data-pltdoc="x">Vectors</a></td></tr><tr><td align="right">3.10 </td><td><a href="hash-tables.html" class="tocviewlink" data-pltdoc="x">Hash Tables</a></td></tr><tr><td align="right">3.11 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Boxes</a></td></tr><tr><td align="right">3.12 </td><td><a href="void_undefined.html" class="tocviewlink" data-pltdoc="x">Void and Undefined</a></td></tr></table></div></div></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="hash-tables.html" title="backward to "3.10 Hash Tables"" data-pltdoc="x">← prev</a> <a href="datatypes.html" title="up to "3 Built-In Datatypes"" data-pltdoc="x">up</a> <a href="void_undefined.html" title="forward to "3.12 Void and Undefined"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-part-tag=""boxes"">3.11<tt> </tt><a name="(part._boxes)"></a>Boxes</h4><p>A <a name="(tech._box)"></a><span style="font-style: italic">box</span> is like a single-element vector. It can print as a
quoted <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#&</span><span class="hspace"></span></span> followed by the printed form of the boxed value.
A <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#&</span><span class="hspace"></span></span> form can also be used as an expression, but since the
resulting box is constant, it has practically no use.</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">b</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=boxes.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._box%2529%2529&version=6.1" class="RktValLink Sq" data-pltdoc="x">box</a></span><span class="hspace"> </span><span class="RktVal">"apple"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktSym">b</span></td></tr><tr><td><p><span class="RktRes">'#&"apple"</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=boxes.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._unbox%2529%2529&version=6.1" class="RktValLink Sq" data-pltdoc="x">unbox</a></span><span class="hspace"> </span><span class="RktSym">b</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">"apple"</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=boxes.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._set-box%2521%2529%2529&version=6.1" class="RktValLink Sq" data-pltdoc="x">set-box!</a></span><span class="hspace"> </span><span class="RktSym">b</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">banana</span><span class="hspace"> </span><span class="RktVal">boat</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktSym">b</span></td></tr><tr><td><p><span class="RktRes">'#&(banana boat)</span></p></td></tr></table></blockquote></td></tr></table></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p><span class="imageleft"><img src="magnify.png" alt="+" width="24" height="24"/></span><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=boxes.html&version=6.1" class="Sq" data-pltdoc="x">Boxes</a> in <a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&rel=index.html&version=6.1" class="Sq" data-pltdoc="x"><span style="font-weight: bold">The Racket Reference</span></a> provides more on boxes and box procedures.</p></blockquote></blockquote></blockquote><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="hash-tables.html" title="backward to "3.10 Hash Tables"" data-pltdoc="x">← prev</a> <a href="datatypes.html" title="up to "3 Built-In Datatypes"" data-pltdoc="x">up</a> <a href="void_undefined.html" title="forward to "3.12 Void and Undefined"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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