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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head>  <meta name="generator" content=  "HTML Tidy for Linux/x86 (vers 1 September 2005), see www.w3.org">  <title>I/O Constructors</title>  <link href="../cppreference.css" rel="stylesheet" type="text/css"></head><body><table>  <tr>  <td>  <div class="body-content">  <div class="header-box">    <a href="../index.html">cppreference.com</a> &gt; <a href=    "index.html">C++ I/O</a> &gt; <a href="constructors.html">I/O    Constructors</a>  </div>  <div class="name-format">    I/O Constructors  </div>  <div class="syntax-name-format">    Syntax:  </div>  <pre class="syntax-box">  #include &lt;fstream&gt;  fstream( const char *filename, openmode mode );  ifstream( const char *filename, openmode mode );  ofstream( const char *filename, openmode mode );</pre>  <p>The fstream, ifstream, and ofstream objects are used to do file  I/O. The optional <em>mode</em> defines how the file is to be opened,  according to the <a href="../io_flags.html#mode_flags">io stream mode  flag</a>s. The optional <em>filename</em> specifies the file to be  opened and associated with the stream.</p>  <p>Input and output file streams can be used in a similar manner to  C++ predefined I/O streams, cin and cout.</p>  <div class="related-examples-format">    Example code:  </div>  <div class="related-examples">    <p>The following code reads input data and appends the result to an    output file.</p>    <pre class="example-code">  ifstream fin( &quot;/tmp/data.txt&quot; );  ofstream fout( &quot;/tmp/results.txt&quot;, ios::app );  while( fin &gt;&gt; temp )    fout &lt;&lt; temp + 2 &lt;&lt; endl;  fin.close();  fout.close();         </pre>  </div>  <div class="related-name-format">    Related topics:  </div>  <div class="related-content">    <a href="close.html">close</a><br>    <a href="open.html">open</a>  </div>  </div>  </td>    </tr>  </table></body></html>

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