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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>13.1.4 Counting Positions, Lines, and Columns</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x"><span style="font-weight: bold">The Racket Reference</span></a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewselflink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">►</a></td><td>13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.1 </td><td><a href="ports.html" class="tocviewselflink" data-pltdoc="x">Ports</a></td></tr><tr><td align="right">13.2 </td><td><a href="Byte_and_String_Input.html" class="tocviewlink" data-pltdoc="x">Byte and String Input</a></td></tr><tr><td align="right">13.3 </td><td><a href="Byte_and_String_Output.html" class="tocviewlink" data-pltdoc="x">Byte and String Output</a></td></tr><tr><td align="right">13.4 </td><td><a href="Reading.html" class="tocviewlink" data-pltdoc="x">Reading</a></td></tr><tr><td align="right">13.5 </td><td><a href="Writing.html" class="tocviewlink" data-pltdoc="x">Writing</a></td></tr><tr><td align="right">13.6 </td><td><a href="pretty-print.html" class="tocviewlink" data-pltdoc="x">Pretty Printing</a></td></tr><tr><td align="right">13.7 </td><td><a href="Reader_Extension.html" class="tocviewlink" data-pltdoc="x">Reader Extension</a></td></tr><tr><td align="right">13.8 </td><td><a href="Printer_Extension.html" class="tocviewlink" data-pltdoc="x">Printer Extension</a></td></tr><tr><td align="right">13.9 </td><td><a href="serialization.html" class="tocviewlink" data-pltdoc="x">Serialization</a></td></tr><tr><td align="right">13.10 </td><td><a href="fasl.html" class="tocviewlink" data-pltdoc="x">Fast-<wbr></wbr>Load Serialization</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_2");">▼</a></td><td>13.1 </td><td><a href="ports.html" class="tocviewlink" data-pltdoc="x">Ports</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.1.1 </td><td><a href="encodings.html" class="tocviewlink" data-pltdoc="x">Encodings and Locales</a></td></tr><tr><td align="right">13.1.2 </td><td><a href="port-ops.html" class="tocviewlink" data-pltdoc="x">Managing Ports</a></td></tr><tr><td align="right">13.1.3 </td><td><a href="port-buffers.html" class="tocviewlink" data-pltdoc="x">Port Buffers and Positions</a></td></tr><tr><td align="right">13.1.4 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Counting Positions, Lines, and Columns</a></td></tr><tr><td align="right">13.1.5 </td><td><a href="file-ports.html" class="tocviewlink" data-pltdoc="x">File Ports</a></td></tr><tr><td align="right">13.1.6 </td><td><a href="stringport.html" class="tocviewlink" data-pltdoc="x">String Ports</a></td></tr><tr><td align="right">13.1.7 </td><td><a href="pipeports.html" class="tocviewlink" data-pltdoc="x">Pipes</a></td></tr><tr><td align="right">13.1.8 </td><td><a href="portstructs.html" class="tocviewlink" data-pltdoc="x">Structures as Ports</a></td></tr><tr><td align="right">13.1.9 </td><td><a href="customport.html" class="tocviewlink" data-pltdoc="x">Custom Ports</a></td></tr><tr><td align="right">13.1.10 </td><td><a href="port-lib.html" class="tocviewlink" data-pltdoc="x">More Port Constructors, Procedures, and Events</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>count-<wbr></wbr>lines!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._port-counts-lines~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>counts-<wbr></wbr>lines?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>next-<wbr></wbr>location</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._set-port-next-location%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">set-<wbr></wbr>port-<wbr></wbr>next-<wbr></wbr>location!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines-enabled%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">port-<wbr></wbr>count-<wbr></wbr>lines-<wbr></wbr>enabled</span></span></a></td></tr></table></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, "6.3", "../");" 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("6.3");">top</a></span><span class="navright"> <a href="port-buffers.html" title="backward to "13.1.3 Port Buffers and Positions"" data-pltdoc="x">← prev</a> <a href="ports.html" title="up to "13.1 Ports"" data-pltdoc="x">up</a> <a href="file-ports.html" title="forward to "13.1.5 File Ports"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""linecol"">13.1.4<tt> </tt><a name="(part._linecol)"></a><a name="(idx._(gentag._205._(lib._scribblings/reference/reference..scrbl)))"></a><a name="(idx._(gentag._206._(lib._scribblings/reference/reference..scrbl)))"></a><a name="(idx._(gentag._207._(lib._scribblings/reference/reference..scrbl)))"></a>Counting Positions, Lines, and Columns</h5><p>By default, Racket keeps track of the <a name="(tech._position)"></a><span style="font-style: italic">position</span> in a port as
the number of bytes that have been read from or written to any port
(independent of the read/write position, which is accessed or changed
with <span class="RktSym"><a href="port-buffers.html#%28def._%28%28quote._~23~25kernel%29._file-position%29%29" class="RktValLink" data-pltdoc="x">file-position</a></span>). Optionally, however, Racket can track
the position in terms of characters (after UTF-8 decoding), instead of
bytes, and it can track <a name="(tech._line._location)"></a><span style="font-style: italic">line locations</span> and <a name="(tech._column._location)"></a><span style="font-style: italic">column
locations</span>; this optional tracking must be specifically enabled for a
port via <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines%21%29%29" class="RktValLink" data-pltdoc="x">port-count-lines!</a></span> or the
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines-enabled%29%29" class="RktValLink" data-pltdoc="x">port-count-lines-enabled</a></span> parameter. Position, line, and
column locations for a port are used by <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%29%29" class="RktValLink" data-pltdoc="x">read-syntax</a></span>.
Position and line locations are numbered
from <span style="font-style: italic"></span>1<span style="font-style: italic"></span>; column locations are numbered from <span style="font-style: italic"></span>0<span style="font-style: italic"></span>.</p><p>When counting lines, Racket treats linefeed, return, and
return-linefeed combinations as a line terminator and as a single
position (on all platforms). Each tab advances the column count to one
before the next multiple of <span style="font-style: italic"></span>8<span style="font-style: italic"></span>. When a sequence of bytes in the
range 128 to 253 forms a UTF-8 encoding of a character, the
position/column is incremented once for each byte, and
then decremented appropriately when a complete encoding sequence is
discovered. See also <a href="ports.html" data-pltdoc="x">Ports</a> for more information on UTF-8
decoding for ports.</p><p>A position is known for any port as long as its value can be expressed
as a fixnum (which is more than enough tracking for realistic
applications in, say, syntax-error reporting). If the position for a
port exceeds the value of the largest fixnum, then the position for
the port becomes unknown, and line and column tacking is disabled.
Return-linefeed combinations are treated as a single character
position only when line and column counting is enabled.</p><p><a href="customport.html#%28tech._custom._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">Custom ports</span></a> can define their own counting functions, which are
not subject to the rules above, except that the counting functions are
invoked only when tracking is specifically enabled with
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines%21%29%29" class="RktValLink" data-pltdoc="x">port-count-lines!</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._port-count-lines!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-count-lines!</a></span></span><span class="hspace"> </span><span class="RktVar">port</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Turns on <a href="#%28tech._line._location%29" class="techoutside" data-pltdoc="x"><span class="techinside">line location</span></a> and <a href="#%28tech._column._location%29" class="techoutside" data-pltdoc="x"><span class="techinside">column location</span></a> counting
for a port. Counting can be turned
on at any time, though generally it is turned on before any data is
read from or written to a port. At the point that line counting is
turned on, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="RktValLink" data-pltdoc="x">port-next-location</a></span> typically starts reporting as
its last result (one more than) the number of characters read since
line counting was enabled, instead of (one more than) bytes read since
the port was opened.</div></p><p>When a port is created, if the value of the
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines-enabled%29%29" class="RktValLink" data-pltdoc="x">port-count-lines-enabled</a></span> parameter is true, then line
counting is automatically enabled for the port. Line counting cannot
be disabled for a port after it is enabled.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._port-counts-lines~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-counts-lines~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-counts-lines?</a></span></span><span class="hspace"> </span><span class="RktVar">port</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <a href="#%28tech._line._location%29" class="techoutside" data-pltdoc="x"><span class="techinside">line location</span></a> and <a href="#%28tech._column._location%29" class="techoutside" data-pltdoc="x"><span class="techinside">column location</span></a>
counting has been enabled for
<span class="RktVar">port</span>, <span class="RktVal">#f</span> otherwise.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._port-next-location))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-next-location</a></span></span><span class="hspace"> </span><span class="RktVar">port</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-positive-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-positive-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-positive-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-positive-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns three values: an integer or <span class="RktVal">#f</span> for the line number of
the next read/written item, an integer or <span class="RktVal">#f</span> for the next
item’s column, and an integer or <span class="RktVal">#f</span> for the next item’s
position. The next column and position normally increase as bytes are
read from or written to the port, but if line/character counting is
enabled for <span class="RktVar">port</span>, the column and position results can
decrease after reading or writing a byte that ends a UTF-8 encoding
sequence.</div></p><p>If line counting is not enabled for a port, than the first two results
are <span class="RktVal">#f</span>, and the last result is one more than the number of
bytes read so far. At the point when line counting is enabled, the
first two results typically become non-<span class="RktVal">#f</span>, and last result
starts reporting characters instead of bytes, typically starting from
the point when line counting is enabled.</p><p>Even with line counting enabled, a port may return <span class="RktVal">#f</span> values
if it somehow cannot keep track of lines, columns, or positions.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._set-port-next-location!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._set-port-next-location%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">set-port-next-location!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">port</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">line</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">column</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">position</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">port</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._port~3f%29%29" class="RktValLink" data-pltdoc="x">port?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">line</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-positive-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-positive-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">column</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">position</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-positive-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-positive-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Sets the next line, column, and position for <span class="RktVar">port</span>. If line
counting has not been enabled for <span class="RktVar">port</span> or if <span class="RktVar">port</span> is
a <a href="customport.html#%28tech._custom._port%29" class="techoutside" data-pltdoc="x"><span class="techinside">custom port</span></a> that defines its own counting function, then
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._set-port-next-location%21%29%29" class="RktValLink" data-pltdoc="x">set-port-next-location!</a></span> has no effect.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._port-count-lines-enabled))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines-enabled%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-count-lines-enabled</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._port-count-lines-enabled%29%29" class="RktValDef RktValLink" data-pltdoc="x">port-count-lines-enabled</a></span></span><span class="hspace"> </span><span class="RktVar">on?</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">on?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameter</span></a> that determines whether line counting is enabled
automatically for newly created ports. The default value is
<span class="RktVal">#f</span>.</div></p><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, "6.3", "../");" 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("6.3");">top</a></span><span class="navright"> <a href="port-buffers.html" title="backward to "13.1.3 Port Buffers and Positions"" data-pltdoc="x">← prev</a> <a href="ports.html" title="up to "13.1 Ports"" data-pltdoc="x">up</a> <a href="file-ports.html" title="forward to "13.1.5 File Ports"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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