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C++ I/O [C++ Reference]
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<h1><a name="c_io" id="c_io">C++ I/O</a></h1>
<div class="level1">
<p>
The <iostream> library automatically defines a few standard objects:
</p>
<ul>
<li class="level1"><div class="li"> cout, an object of the ostream class, which displays data to the standard output device.</div>
</li>
<li class="level1"><div class="li"> cerr, another object of the ostream class that writes unbuffered output to the standard error device.</div>
</li>
<li class="level1"><div class="li"> clog, like cerr, but uses buffered output.</div>
</li>
<li class="level1"><div class="li"> cin, an object of the istream class that reads data from the standard input device.</div>
</li>
</ul>
<p>
The <fstream> library allows programmers to do file input and output
with the ifstream and ofstream classes. C++ programmers can also do
input and output from strings by using the <a href="../io/sstream/start.html" class="wikilink1" title="io:sstream:start">stringstream</a> class.
</p>
<p>
Some of the behavior of the C++ I/O streams (precision, justification,
etc) may be modified by manipulating various <a href="../io/io_flags.html" class="wikilink1" title="io:io_flags">I/O stream
format flags</a>.
</p>
<table class="inline">
<tr class="row0">
<td class="col0"><a href="../io/constructors.html" class="wikilink1" title="io:constructors">I/O Constructors</a></td><td class="col1">constructors</td>
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<td class="col0"><a href="../io/bad.html" class="wikilink1" title="io:bad">bad</a></td><td class="col1">true if an error occurred</td>
</tr>
<tr class="row2">
<td class="col0"><a href="../io/clear.html" class="wikilink1" title="io:clear">clear</a></td><td class="col1">clear and set status flags</td>
</tr>
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<td class="col0"><a href="../io/close.html" class="wikilink1" title="io:close">close</a></td><td class="col1">close a stream</td>
</tr>
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<td class="col0"><a href="../io/eof.html" class="wikilink1" title="io:eof">eof</a></td><td class="col1">true if at the end-of-file</td>
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<td class="col0"><a href="../io/exceptions.html" class="wikilink1" title="io:exceptions">exceptions</a></td><td class="col1">set the stream to throw exceptions on errors</td>
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<td class="col0"><a href="../io/fail.html" class="wikilink1" title="io:fail">fail</a></td><td class="col1">true if an error occurred</td>
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<td class="col0"><a href="../io/fill.html" class="wikilink1" title="io:fill">fill</a></td><td class="col1">manipulate the default fill character</td>
</tr>
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<td class="col0"><a href="../io/flags.html" class="wikilink1" title="io:flags">flags</a></td><td class="col1">access or manipulate io_stream_format_flags</td>
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<td class="col0"><a href="../io/flush.html" class="wikilink1" title="io:flush">flush</a></td><td class="col1">empty the buffer</td>
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<td class="col0"><a href="../io/gcount.html" class="wikilink1" title="io:gcount">gcount</a></td><td class="col1">number of characters read during last input</td>
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<td class="col0"><a href="../io/get.html" class="wikilink1" title="io:get">get</a></td><td class="col1">read characters</td>
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<td class="col0"><a href="../io/getline.html" class="wikilink1" title="io:getline">getline</a></td><td class="col1">read a line of characters</td>
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<td class="col0"><a href="../io/good.html" class="wikilink1" title="io:good">good</a></td><td class="col1">true if no errors have occurred</td>
</tr>
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<td class="col0"><a href="../io/ignore.html" class="wikilink1" title="io:ignore">ignore</a></td><td class="col1">read and discard characters</td>
</tr>
<tr class="row15">
<td class="col0"><a href="../io/is_open.html" class="wikilink1" title="io:is_open">is_open</a></td><td class="col1">check if a file is open</td>
</tr>
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<td class="col0"><a href="../io/open.html" class="wikilink1" title="io:open">open</a></td><td class="col1">open a new stream</td>
</tr>
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<td class="col0"><a href="../io/peek.html" class="wikilink1" title="io:peek">peek</a></td><td class="col1">check the next input character</td>
</tr>
<tr class="row18">
<td class="col0"><a href="../io/precision.html" class="wikilink1" title="io:precision">precision</a></td><td class="col1">manipulate the precision of a stream</td>
</tr>
<tr class="row19">
<td class="col0"><a href="../io/put.html" class="wikilink1" title="io:put">put</a></td><td class="col1">write characters</td>
</tr>
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<td class="col0"><a href="../io/putback.html" class="wikilink1" title="io:putback">putback</a></td><td class="col1">return characters to a stream</td>
</tr>
<tr class="row21">
<td class="col0"><a href="../io/rdstate.html" class="wikilink1" title="io:rdstate">rdstate</a></td><td class="col1">returns the state flags of the stream</td>
</tr>
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<td class="col0"><a href="../io/read.html" class="wikilink1" title="io:read">read</a></td><td class="col1">read data into a buffer</td>
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<td class="col0"><a href="../io/seekg.html" class="wikilink1" title="io:seekg">seekg</a></td><td class="col1">perform random access on an input stream</td>
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<td class="col0"><a href="../io/seekp.html" class="wikilink1" title="io:seekp">seekp</a></td><td class="col1">perform random access on output streams</td>
</tr>
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<td class="col0"><a href="../io/setf.html" class="wikilink1" title="io:setf">setf</a></td><td class="col1">set format flags</td>
</tr>
<tr class="row26">
<td class="col0"><a href="../io/sync_with_stdio.html" class="wikilink1" title="io:sync_with_stdio">sync_with_stdio</a></td><td class="col1">synchronize with standard I/O</td>
</tr>
<tr class="row27">
<td class="col0"><a href="../io/tellg.html" class="wikilink1" title="io:tellg">tellg</a></td><td class="col1">read input stream pointers</td>
</tr>
<tr class="row28">
<td class="col0"><a href="../io/tellp.html" class="wikilink1" title="io:tellp">tellp</a></td><td class="col1">read output stream pointers</td>
</tr>
<tr class="row29">
<td class="col0"><a href="../io/unsetf.html" class="wikilink1" title="io:unsetf">unsetf</a></td><td class="col1">clear io_stream_format_flags</td>
</tr>
<tr class="row30">
<td class="col0"><a href="../io/width.html" class="wikilink1" title="io:width">width</a></td><td class="col1">access and manipulate the minimum field width</td>
</tr>
<tr class="row31">
<td class="col0"><a href="../io/write.html" class="wikilink1" title="io:write">write</a></td><td class="col1">write characters</td>
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