154 lines
6.0 KiB
HTML
154 lines
6.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>fgets</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="fgets"></a> <a name="tag_03_164"></a><!-- fgets -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_164_01"></a>NAME</h4>
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<blockquote>fgets - get a string from a stream</blockquote>
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<h4><a name="tag_03_164_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/stdio.h.html">stdio.h</a>><br>
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<br>
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char *fgets(char *restrict</tt> <i>s</i><tt>, int</tt> <i>n</i><tt>, FILE *restrict</tt> <i>stream</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_164_03"></a>DESCRIPTION</h4>
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<blockquote>
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<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
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border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
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requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
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the ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
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<p>The <i>fgets</i>() function shall read bytes from <i>stream</i> into the array pointed to by <i>s</i>, until <i>n</i>-1 bytes
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are read, or a <newline> is read and transferred to <i>s</i>, or an end-of-file condition is encountered. The string is then
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terminated with a null byte.</p>
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<p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> The
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<i>fgets</i>() function may mark the <i>st_atime</i> field of the file associated with <i>stream</i> for update. The
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<i>st_atime</i> field shall be marked for update by the first successful execution of <a href=
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"../functions/fgetc.html"><i>fgetc</i>()</a>, <i>fgets</i>(), <a href="../functions/fgetwc.html"><i>fgetwc</i>()</a>, <a href=
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"../functions/fgetws.html"><i>fgetws</i>()</a>, <a href="../functions/fread.html"><i>fread</i>()</a>, <a href=
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"../functions/fscanf.html"><i>fscanf</i>()</a>, <a href="../functions/getc.html"><i>getc</i>()</a>, <a href=
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"../functions/getchar.html"><i>getchar</i>()</a>, <a href="../functions/gets.html"><i>gets</i>()</a>, or <a href=
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"../functions/scanf.html"><i>scanf</i>()</a> using <i>stream</i> that returns data not supplied by a prior call to <a href=
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"../functions/ungetc.html"><i>ungetc</i>()</a> or <a href="../functions/ungetwc.html"><i>ungetwc</i>()</a>. <img src=
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"../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_164_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>fgets</i>() shall return <i>s</i>. If the stream is at end-of-file, the end-of-file indicator for
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the stream shall be set and <i>fgets</i>() shall return a null pointer. If a read error occurs, the error indicator for the stream
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shall be set, <i>fgets</i>() shall return a null pointer, <sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src=
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"../images/opt-start.gif" alt="[Option Start]" border="0"> and shall set <i>errno</i> to indicate the error. <img src=
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"../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_164_05"></a>ERRORS</h4>
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<blockquote>
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<p>Refer to <a href="fgetc.html"><i>fgetc</i>()</a> .</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_164_06"></a>EXAMPLES</h4>
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<blockquote>
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<h5><a name="tag_03_164_06_01"></a>Reading Input</h5>
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<p>The following example uses <i>fgets</i>() to read each line of input. {LINE_MAX}, which defines the maximum size of the input
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line, is defined in the <a href="../basedefs/limits.h.html"><i><limits.h></i></a> header.</p>
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<pre>
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<tt>#include <stdio.h>
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...
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char line[LINE_MAX];
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...
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while (fgets(line, LINE_MAX, fp) != NULL) {
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...
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}
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...
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_164_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_164_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_164_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_164_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="fopen.html"><i>fopen</i>()</a> , <a href="fread.html"><i>fread</i>()</a> , <a href="gets.html"><i>gets</i>()</a> , the
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Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_164_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_164_12"></a>Issue 6</h4>
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<blockquote>
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<p>Extensions beyond the ISO C standard are marked.</p>
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<p>The prototype for <i>fgets</i>() is changed for alignment with the ISO/IEC 9899:1999 standard.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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