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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>35.2. msvcrt — Useful routines from the MS VC++ runtime — Python 2.7.18 documentation</title> <link rel="stylesheet" href="../_static/classic.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 2.7.18 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="35.3. _winreg — Windows registry access" href="_winreg.html" /> <link rel="prev" title="35.1. msilib — Read and write Microsoft Installer files" href="msilib.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="file:///usr/share/doc/python2.7/html/library/msvcrt.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head><body> <div id="outdated-warning" style="padding: .5em; text-align: center; background-color: #FFBABA; color: #6A0E0E;"> This document is for an old version of Python that is <a href="https://devguide.python.org/devcycle/#end-of-life-branches">no longer supported</a>. 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MS Windows Specific Services</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-msvcrt"> <span id="msvcrt-useful-routines-from-the-ms-vc-runtime"></span><h1>35.2. <a class="reference internal" href="#module-msvcrt" title="msvcrt: Miscellaneous useful routines from the MS VC++ runtime. (Windows)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">msvcrt</span></code></a> — Useful routines from the MS VC++ runtime<a class="headerlink" href="#module-msvcrt" title="Permalink to this headline">¶</a></h1> <p>These functions provide access to some useful capabilities on Windows platforms. Some higher-level modules use these functions to build the Windows implementations of their services. For example, the <a class="reference internal" href="getpass.html#module-getpass" title="getpass: Portable reading of passwords and retrieval of the userid."><code class="xref py py-mod docutils literal notranslate"><span class="pre">getpass</span></code></a> module uses this in the implementation of the <a class="reference internal" href="getpass.html#module-getpass" title="getpass: Portable reading of passwords and retrieval of the userid."><code class="xref py py-func docutils literal notranslate"><span class="pre">getpass()</span></code></a> function.</p> <p>Further documentation on these functions can be found in the Platform API documentation.</p> <p>The module implements both the normal and wide char variants of the console I/O api. The normal API deals only with ASCII characters and is of limited use for internationalized applications. The wide char API should be used where ever possible.</p> <div class="section" id="file-operations"> <span id="msvcrt-files"></span><h2>35.2.1. File Operations<a class="headerlink" href="#file-operations" title="Permalink to this headline">¶</a></h2> <dl class="function"> <dt id="msvcrt.locking"> <code class="descclassname">msvcrt.</code><code class="descname">locking</code><span class="sig-paren">(</span><em>fd</em>, <em>mode</em>, <em>nbytes</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.locking" title="Permalink to this definition">¶</a></dt> <dd><p>Lock part of a file based on file descriptor <em>fd</em> from the C runtime. Raises <a class="reference internal" href="exceptions.html#exceptions.IOError" title="exceptions.IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a> on failure. The locked region of the file extends from the current file position for <em>nbytes</em> bytes, and may continue beyond the end of the file. <em>mode</em> must be one of the <code class="xref py py-const docutils literal notranslate"><span class="pre">LK_*</span></code> constants listed below. Multiple regions in a file may be locked at the same time, but may not overlap. Adjacent regions are not merged; they must be unlocked individually.</p> </dd></dl> <dl class="data"> <dt id="msvcrt.LK_LOCK"> <code class="descclassname">msvcrt.</code><code class="descname">LK_LOCK</code><a class="headerlink" href="#msvcrt.LK_LOCK" title="Permalink to this definition">¶</a></dt> <dt id="msvcrt.LK_RLCK"> <code class="descclassname">msvcrt.</code><code class="descname">LK_RLCK</code><a class="headerlink" href="#msvcrt.LK_RLCK" title="Permalink to this definition">¶</a></dt> <dd><p>Locks the specified bytes. If the bytes cannot be locked, the program immediately tries again after 1 second. If, after 10 attempts, the bytes cannot be locked, <a class="reference internal" href="exceptions.html#exceptions.IOError" title="exceptions.IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a> is raised.</p> </dd></dl> <dl class="data"> <dt id="msvcrt.LK_NBLCK"> <code class="descclassname">msvcrt.</code><code class="descname">LK_NBLCK</code><a class="headerlink" href="#msvcrt.LK_NBLCK" title="Permalink to this definition">¶</a></dt> <dt id="msvcrt.LK_NBRLCK"> <code class="descclassname">msvcrt.</code><code class="descname">LK_NBRLCK</code><a class="headerlink" href="#msvcrt.LK_NBRLCK" title="Permalink to this definition">¶</a></dt> <dd><p>Locks the specified bytes. If the bytes cannot be locked, <a class="reference internal" href="exceptions.html#exceptions.IOError" title="exceptions.IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a> is raised.</p> </dd></dl> <dl class="data"> <dt id="msvcrt.LK_UNLCK"> <code class="descclassname">msvcrt.</code><code class="descname">LK_UNLCK</code><a class="headerlink" href="#msvcrt.LK_UNLCK" title="Permalink to this definition">¶</a></dt> <dd><p>Unlocks the specified bytes, which must have been previously locked.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.setmode"> <code class="descclassname">msvcrt.</code><code class="descname">setmode</code><span class="sig-paren">(</span><em>fd</em>, <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.setmode" title="Permalink to this definition">¶</a></dt> <dd><p>Set the line-end translation mode for the file descriptor <em>fd</em>. To set it to text mode, <em>flags</em> should be <a class="reference internal" href="os.html#os.O_TEXT" title="os.O_TEXT"><code class="xref py py-const docutils literal notranslate"><span class="pre">os.O_TEXT</span></code></a>; for binary, it should be <a class="reference internal" href="os.html#os.O_BINARY" title="os.O_BINARY"><code class="xref py py-const docutils literal notranslate"><span class="pre">os.O_BINARY</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.open_osfhandle"> <code class="descclassname">msvcrt.</code><code class="descname">open_osfhandle</code><span class="sig-paren">(</span><em>handle</em>, <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.open_osfhandle" title="Permalink to this definition">¶</a></dt> <dd><p>Create a C runtime file descriptor from the file handle <em>handle</em>. The <em>flags</em> parameter should be a bitwise OR of <a class="reference internal" href="os.html#os.O_APPEND" title="os.O_APPEND"><code class="xref py py-const docutils literal notranslate"><span class="pre">os.O_APPEND</span></code></a>, <a class="reference internal" href="os.html#os.O_RDONLY" title="os.O_RDONLY"><code class="xref py py-const docutils literal notranslate"><span class="pre">os.O_RDONLY</span></code></a>, and <a class="reference internal" href="os.html#os.O_TEXT" title="os.O_TEXT"><code class="xref py py-const docutils literal notranslate"><span class="pre">os.O_TEXT</span></code></a>. The returned file descriptor may be used as a parameter to <a class="reference internal" href="os.html#os.fdopen" title="os.fdopen"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.fdopen()</span></code></a> to create a file object.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.get_osfhandle"> <code class="descclassname">msvcrt.</code><code class="descname">get_osfhandle</code><span class="sig-paren">(</span><em>fd</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.get_osfhandle" title="Permalink to this definition">¶</a></dt> <dd><p>Return the file handle for the file descriptor <em>fd</em>. Raises <a class="reference internal" href="exceptions.html#exceptions.IOError" title="exceptions.IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a> if <em>fd</em> is not recognized.</p> </dd></dl> </div> <div class="section" id="console-i-o"> <span id="msvcrt-console"></span><h2>35.2.2. Console I/O<a class="headerlink" href="#console-i-o" title="Permalink to this headline">¶</a></h2> <dl class="function"> <dt id="msvcrt.kbhit"> <code class="descclassname">msvcrt.</code><code class="descname">kbhit</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.kbhit" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if a keypress is waiting to be read.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.getch"> <code class="descclassname">msvcrt.</code><code class="descname">getch</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.getch" title="Permalink to this definition">¶</a></dt> <dd><p>Read a keypress and return the resulting character. Nothing is echoed to the console. This call will block if a keypress is not already available, but will not wait for <kbd class="kbd docutils literal notranslate">Enter</kbd> to be pressed. If the pressed key was a special function key, this will return <code class="docutils literal notranslate"><span class="pre">'\000'</span></code> or <code class="docutils literal notranslate"><span class="pre">'\xe0'</span></code>; the next call will return the keycode. The <kbd class="kbd docutils literal notranslate">Control-C</kbd> keypress cannot be read with this function.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.getwch"> <code class="descclassname">msvcrt.</code><code class="descname">getwch</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.getwch" title="Permalink to this definition">¶</a></dt> <dd><p>Wide char variant of <a class="reference internal" href="#msvcrt.getch" title="msvcrt.getch"><code class="xref py py-func docutils literal notranslate"><span class="pre">getch()</span></code></a>, returning a Unicode value.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 2.6.</span></p> </div> </dd></dl> <dl class="function"> <dt id="msvcrt.getche"> <code class="descclassname">msvcrt.</code><code class="descname">getche</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.getche" title="Permalink to this definition">¶</a></dt> <dd><p>Similar to <a class="reference internal" href="#msvcrt.getch" title="msvcrt.getch"><code class="xref py py-func docutils literal notranslate"><span class="pre">getch()</span></code></a>, but the keypress will be echoed if it represents a printable character.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.getwche"> <code class="descclassname">msvcrt.</code><code class="descname">getwche</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.getwche" title="Permalink to this definition">¶</a></dt> <dd><p>Wide char variant of <a class="reference internal" href="#msvcrt.getche" title="msvcrt.getche"><code class="xref py py-func docutils literal notranslate"><span class="pre">getche()</span></code></a>, returning a Unicode value.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 2.6.</span></p> </div> </dd></dl> <dl class="function"> <dt id="msvcrt.putch"> <code class="descclassname">msvcrt.</code><code class="descname">putch</code><span class="sig-paren">(</span><em>char</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.putch" title="Permalink to this definition">¶</a></dt> <dd><p>Print the character <em>char</em> to the console without buffering.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.putwch"> <code class="descclassname">msvcrt.</code><code class="descname">putwch</code><span class="sig-paren">(</span><em>unicode_char</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.putwch" title="Permalink to this definition">¶</a></dt> <dd><p>Wide char variant of <a class="reference internal" href="#msvcrt.putch" title="msvcrt.putch"><code class="xref py py-func docutils literal notranslate"><span class="pre">putch()</span></code></a>, accepting a Unicode value.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 2.6.</span></p> </div> </dd></dl> <dl class="function"> <dt id="msvcrt.ungetch"> <code class="descclassname">msvcrt.</code><code class="descname">ungetch</code><span class="sig-paren">(</span><em>char</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.ungetch" title="Permalink to this definition">¶</a></dt> <dd><p>Cause the character <em>char</em> to be “pushed back” into the console buffer; it will be the next character read by <a class="reference internal" href="#msvcrt.getch" title="msvcrt.getch"><code class="xref py py-func docutils literal notranslate"><span class="pre">getch()</span></code></a> or <a class="reference internal" href="#msvcrt.getche" title="msvcrt.getche"><code class="xref py py-func docutils literal notranslate"><span class="pre">getche()</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="msvcrt.ungetwch"> <code class="descclassname">msvcrt.</code><code class="descname">ungetwch</code><span class="sig-paren">(</span><em>unicode_char</em><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.ungetwch" title="Permalink to this definition">¶</a></dt> <dd><p>Wide char variant of <a class="reference internal" href="#msvcrt.ungetch" title="msvcrt.ungetch"><code class="xref py py-func docutils literal notranslate"><span class="pre">ungetch()</span></code></a>, accepting a Unicode value.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 2.6.</span></p> </div> </dd></dl> </div> <div class="section" id="other-functions"> <span id="msvcrt-other"></span><h2>35.2.3. Other Functions<a class="headerlink" href="#other-functions" title="Permalink to this headline">¶</a></h2> <dl class="function"> <dt id="msvcrt.heapmin"> <code class="descclassname">msvcrt.</code><code class="descname">heapmin</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#msvcrt.heapmin" title="Permalink to this definition">¶</a></dt> <dd><p>Force the <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code> heap to clean itself up and return unused blocks to the operating system. On failure, this raises <a class="reference internal" href="exceptions.html#exceptions.IOError" title="exceptions.IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a>.</p> </dd></dl> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table of Contents</a></h3> <ul> <li><a class="reference internal" href="#">35.2. <code class="docutils literal notranslate"><span class="pre">msvcrt</span></code> — Useful routines from the MS VC++ runtime</a><ul> <li><a class="reference internal" href="#file-operations">35.2.1. File Operations</a></li> <li><a class="reference internal" href="#console-i-o">35.2.2. Console I/O</a></li> <li><a class="reference internal" href="#other-functions">35.2.3. Other Functions</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="msilib.html" title="previous chapter">35.1. <code class="docutils literal notranslate"><span class="pre">msilib</span></code> — Read and write Microsoft Installer files</a></p> <h4>Next topic</h4> <p class="topless"><a href="_winreg.html" title="next chapter">35.3. <code class="docutils literal notranslate"><span class="pre">_winreg</span></code> — Windows registry access</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../_sources/library/msvcrt.rst.txt" rel="nofollow">Show Source</a></li> </ul> </div> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <div class="searchformwrapper"> <form class="search" action="../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="_winreg.html" title="35.3. _winreg — Windows registry access" >next</a> |</li> <li class="right" > <a href="msilib.html" title="35.1. msilib — Read and write Microsoft Installer files" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.18 documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="windows.html" >35. 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