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Public domain. 0059 Originally written by Jim Hefferon and Karl Berry, 2018. */ 0060 0061 /* So you can style for yourself */ 0062 @import url("/css/latexreflocal.css"); 0063 0064 0065 0066 a.summary-letter {text-decoration: none} 0067 blockquote.indentedblock {margin-right: 0em} 0068 blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 0069 blockquote.smallquotation {font-size: smaller} 0070 div.display {margin-left: 3.2em} 0071 div.example {margin-left: 3.2em} 0072 div.lisp {margin-left: 3.2em} 0073 div.smalldisplay {margin-left: 3.2em} 0074 div.smallexample {margin-left: 3.2em} 0075 div.smalllisp {margin-left: 3.2em} 0076 kbd {font-style: oblique} 0077 pre.display {font-family: inherit} 0078 pre.format {font-family: inherit} 0079 pre.menu-comment {font-family: serif} 0080 pre.menu-preformatted {font-family: serif} 0081 pre.smalldisplay {font-family: inherit; font-size: smaller} 0082 pre.smallexample {font-size: smaller} 0083 pre.smallformat {font-family: inherit; font-size: smaller} 0084 pre.smalllisp {font-size: smaller} 0085 span.nolinebreak {white-space: nowrap} 0086 span.roman {font-family: initial; font-weight: normal} 0087 span.sansserif {font-family: sans-serif; font-weight: normal} 0088 ul.no-bullet {list-style: none} 0089 BODY { 0090 margin-top: 1em; 0091 margin-left: 1em; /* auto results in two-digit <ol> lost off left */ 0092 margin-right: 1em; 0093 margin-bottom: 1em; 0094 /* the idea is to use the whole window, unless it is ridiculously 0095 wide, probably with too-small fonts, too. */ 0096 max-width: 64em; 0097 } 0098 0099 /* Because we want @math{... @code ...} to be upright, not slanted, 0100 and Texinfo won't fix it. */ 0101 code {font-style:normal; font-family:monospace; } 0102 0103 /* We put a link to our own home page at the bottom. */ 0104 div.referenceinfo {font-size:small;} 0105 0106 --> 0107 </style> 0108 0109 0110 </head> 0111 0112 <body lang="en"> 0113 <a name="g_t_005copenin-_0026-_005copenout"></a> 0114 <div class="header"> 0115 <p> 0116 Next: <a href="_005cread.html#g_t_005cread" accesskey="n" rel="next">\read</a>, Up: <a href="Input_002foutput.html#Input_002foutput" accesskey="u" rel="up">Input/output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="IndexDocument.html#Index" title="Index" rel="index">Index</a>]</p> 0117 </div> 0118 <hr> 0119 <a name="g_t_005copenin-_0026-_005copenout-1"></a> 0120 <h3 class="section">27.1 <code>\openin</code> & <code>\openout</code></h3> 0121 0122 <a name="index-_005copenin"></a> 0123 <a name="index-_005copenout"></a> 0124 <a name="index-_005cclosein"></a> 0125 <a name="index-_005ccloseout"></a> 0126 <a name="index-file_002c-opening"></a> 0127 <a name="index-file_002c-closing"></a> 0128 <a name="index-open-a-file"></a> 0129 0130 <p>Synopsis: 0131 </p> 0132 <div class="example"> 0133 <pre class="example">\openin<var>number</var>=<var>filename</var> 0134 </pre></div> 0135 0136 <p>or: 0137 </p> 0138 <div class="example"> 0139 <pre class="example">\openout<var>number</var>=<var>filename</var> 0140 </pre></div> 0141 0142 <p>Open a file for reading material, or for writing it. The <var>number</var> 0143 must be between 0 and 15, as in <code>\openin3</code> (in LuaLaTeX 0144 <var>number</var> can be between 0 and 255). 0145 </p> 0146 <p>Here TeX opens the file <samp>presidents.tex</samp> for reading. 0147 </p> 0148 <div class="example"> 0149 <pre class="example">\newread\presidentsfile 0150 \openin\presidentsfile=presidents 0151 \typeout{presidentsfile is \the\presidentsfile} 0152 \read\presidentsfile to\presidentline 0153 \typeout{\presidentline} 0154 </pre></div> 0155 0156 <p>The <code>\newread</code> command allocates input stream numbers from 0 0157 to 15 (there is also a <code>\newwrite</code>). The 0158 <code>\presidentsfile</code> is more memorable but under the hood it is still 0159 a number; the first <code>\typeout</code> gives something like 0160 ‘<samp>presidentsfile is 1</samp>’. In addition, <code>\newread</code> keeps track of 0161 the allocation so that if you use too many then you get an error like 0162 ‘<samp>! No room for a new \read</samp>’. The second <code>\typeout</code> gives the 0163 first line of the file, something like ‘<samp>1 Washington, George</samp>’. 0164 </p> 0165 <p>Ordinarily TeX will not try to open the file until the next page 0166 shipout. To change this, use 0167 <code>\immediate\openin<var>number</var>=<var>filename</var></code> or 0168 <code>\immediate\openout<var>number</var>=<var>filename</var></code>. 0169 </p> 0170 <p>Close files with <code>\closein<var>number</var></code> and 0171 <code>\closeout<var>number</var></code>. 0172 </p> 0173 <p>How LaTeX handles filenames varies among distributions, and even can 0174 vary among versions of a distribution. If the file does not have an 0175 extension then TeX will add a <samp>.tex</samp>. This creates 0176 <samp>presidents.tex</samp>, writes one line to it, and closes it. 0177 </p> 0178 <div class="example"> 0179 <pre class="example">\newwrite\presidentsfile 0180 \openout\presidentsfile=presidents 0181 \write\presidentsfile{1 Washington, George} 0182 \closeout\presidentsfile 0183 </pre></div> 0184 0185 <p>But filenames with a period can cause trouble: if TeX finds a 0186 <var>filename</var> of <samp>presidents.dat</samp> it could look first for 0187 <samp>presidents.dat.tex</samp> and later for <samp>presidents.dat</samp>, or it 0188 could do the opposite. Your distribution’s documentation should say 0189 more, and if you find something that works for you then you are good, 0190 but to ensure complete portability the best thing is to use file names 0191 containing only the twenty six ASCII letters (not case-sensitive) and 0192 the ten digits, along with underscore and dash, and in particular with 0193 no dot or space. 0194 </p> 0195 <p>For <code>openin</code>, if TeX cannot find the file then it does not give 0196 an error. It just considers that the stream is not open (test for this 0197 with <code>\ifeof</code>; one recourse is the command 0198 <code>\InputIfFileExists</code>, see <a href="Class-and-package-commands.html#Class-and-package-commands">Class and package commands</a>). If you 0199 try to use the same number twice, LaTeX won’t give you an error. If 0200 you try to use a bad number then you get an error message like ‘<samp>! 0201 Bad number (16). <to be read again> = l.30 \openin16=test.jh</samp>’. 0202 </p> 0203 0204 0205 0206 <hr/><div class='referenceinfo'> <a href='https://latexref.xyz/'> <i>Unofficial LaTeX2e reference manual</i></a></div> 0207 </body> 0208 </html>