file.html
来自「perl教程」· HTML 代码 · 共 189 行
HTML
189 行
<?xml version="1.0" ?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<!-- saved from url=(0017)http://localhost/ -->
<script language="JavaScript" src="../../displayToc.js"></script>
<script language="JavaScript" src="../../tocParas.js"></script>
<script language="JavaScript" src="../../tocTab.js"></script>
<link rel="stylesheet" type="text/css" href="../../scineplex.css">
<title>IO::File - supply object methods for filehandles</title>
<link rel="stylesheet" href="../../Active.css" type="text/css" />
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<link rev="made" href="mailto:" />
</head>
<body>
<script>writelinks('__top__',2);</script>
<h1><a>IO::File - supply object methods for filehandles</a></h1>
<p><a name="__index__"></a></p>
<!-- INDEX BEGIN -->
<ul>
<li><a href="#name">NAME</a></li>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#constructor">CONSTRUCTOR</a></li>
<li><a href="#methods">METHODS</a></li>
<li><a href="#note">NOTE</a></li>
<li><a href="#see_also">SEE ALSO</a></li>
<li><a href="#history">HISTORY</a></li>
</ul>
<!-- INDEX END -->
<hr />
<p>
</p>
<h1><a name="name">NAME</a></h1>
<p>IO::File - supply object methods for filehandles</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
<span class="keyword">use</span> <span class="variable">IO::File</span><span class="operator">;</span>
</pre>
<pre>
<span class="variable">$fh</span> <span class="operator">=</span> <span class="variable">new</span> <span class="variable">IO::File</span><span class="operator">;</span>
<span class="keyword">if</span> <span class="operator">(</span><span class="variable">$fh</span><span class="operator">-></span><span class="keyword">open</span><span class="operator">(</span><span class="string">"< file"</span><span class="operator">))</span> <span class="operator">{</span>
<span class="keyword">print</span> <span class="operator"><</span><span class="variable">$fh</span><span class="operator">>;</span>
<span class="variable">$fh</span><span class="operator">-></span><span class="keyword">close</span><span class="operator">;</span>
<span class="operator">}</span>
</pre>
<pre>
<span class="variable">$fh</span> <span class="operator">=</span> <span class="variable">new</span> <span class="variable">IO::File</span> <span class="string">"> file"</span><span class="operator">;</span>
<span class="keyword">if</span> <span class="operator">(</span><span class="keyword">defined</span> <span class="variable">$fh</span><span class="operator">)</span> <span class="operator">{</span>
<span class="keyword">print</span> <span class="variable">$fh</span> <span class="string">"bar\n"</span><span class="operator">;</span>
<span class="variable">$fh</span><span class="operator">-></span><span class="keyword">close</span><span class="operator">;</span>
<span class="operator">}</span>
</pre>
<pre>
<span class="variable">$fh</span> <span class="operator">=</span> <span class="variable">new</span> <span class="variable">IO::File</span> <span class="string">"file"</span><span class="operator">,</span> <span class="string">"r"</span><span class="operator">;</span>
<span class="keyword">if</span> <span class="operator">(</span><span class="keyword">defined</span> <span class="variable">$fh</span><span class="operator">)</span> <span class="operator">{</span>
<span class="keyword">print</span> <span class="operator"><</span><span class="variable">$fh</span><span class="operator">>;</span>
<span class="keyword">undef</span> <span class="variable">$fh</span><span class="operator">;</span> <span class="comment"># automatically closes the file</span>
<span class="operator">}</span>
</pre>
<pre>
<span class="variable">$fh</span> <span class="operator">=</span> <span class="variable">new</span> <span class="variable">IO::File</span> <span class="string">"file"</span><span class="operator">,</span> <span class="variable">O_WRONLY</span><span class="operator">|</span><span class="variable">O_APPEND</span><span class="operator">;</span>
<span class="keyword">if</span> <span class="operator">(</span><span class="keyword">defined</span> <span class="variable">$fh</span><span class="operator">)</span> <span class="operator">{</span>
<span class="keyword">print</span> <span class="variable">$fh</span> <span class="string">"corge\n"</span><span class="operator">;</span>
</pre>
<pre>
<span class="variable">$pos</span> <span class="operator">=</span> <span class="variable">$fh</span><span class="operator">-></span><span class="variable">getpos</span><span class="operator">;</span>
<span class="variable">$fh</span><span class="operator">-></span><span class="variable">setpos</span><span class="operator">(</span><span class="variable">$pos</span><span class="operator">);</span>
</pre>
<pre>
<span class="keyword">undef</span> <span class="variable">$fh</span><span class="operator">;</span> <span class="comment"># automatically closes the file</span>
<span class="operator">}</span>
</pre>
<pre>
<span class="variable">autoflush</span> <span class="variable">STDOUT</span> <span class="number">1</span><span class="operator">;</span>
</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p><code>IO::File</code> inherits from <code>IO::Handle</code> and <code>IO::Seekable</code>. It extends
these classes with methods that are specific to file handles.</p>
<p>
</p>
<hr />
<h1><a name="constructor">CONSTRUCTOR</a></h1>
<dl>
<dt><strong><a name="item_new">new ( FILENAME [,MODE [,PERMS]] )</a></strong>
<dd>
<p>Creates an <code>IO::File</code>. If it receives any parameters, they are passed to
the method <a href="#item_open"><code>open</code></a>; if the open fails, the object is destroyed. Otherwise,
it is returned to the caller.</p>
</dd>
</li>
<dt><strong><a name="item_new_tmpfile">new_tmpfile</a></strong>
<dd>
<p>Creates an <code>IO::File</code> opened for read/write on a newly created temporary
file. On systems where this is possible, the temporary file is anonymous
(i.e. it is unlinked after creation, but held open). If the temporary
file cannot be created or opened, the <code>IO::File</code> object is destroyed.
Otherwise, it is returned to the caller.</p>
</dd>
</li>
</dl>
<p>
</p>
<hr />
<h1><a name="methods">METHODS</a></h1>
<dl>
<dt><strong><a name="item_open">open( FILENAME [,MODE [,PERMS]] )</a></strong>
<dt><strong>open( FILENAME, IOLAYERS )</strong>
<dd>
<p><a href="#item_open"><code>open</code></a> accepts one, two or three parameters. With one parameter,
it is just a front end for the built-in <a href="#item_open"><code>open</code></a> function. With two or three
parameters, the first parameter is a filename that may include
whitespace or other special characters, and the second parameter is
the open mode, optionally followed by a file permission value.</p>
</dd>
<dd>
<p>If <code>IO::File::open</code> receives a Perl mode string (">", "+<", etc.)
or an ANSI C <code>fopen()</code> mode string ("w", "r+", etc.), it uses the basic
Perl <a href="#item_open"><code>open</code></a> operator (but protects any special characters).</p>
</dd>
<dd>
<p>If <code>IO::File::open</code> is given a numeric mode, it passes that mode
and the optional permissions value to the Perl <a href="../../lib/Pod/perlfunc.html#item_sysopen"><code>sysopen</code></a> operator.
The permissions default to 0666.</p>
</dd>
<dd>
<p>If <code>IO::File::open</code> is given a mode that includes the <code>:</code> character,
it passes all the three arguments to the three-argument <a href="#item_open"><code>open</code></a> operator.</p>
</dd>
<dd>
<p>For convenience, <code>IO::File</code> exports the O_XXX constants from the
Fcntl module, if this module is available.</p>
</dd>
</li>
<dt><strong><a name="item_binmode">binmode( [LAYER] )</a></strong>
<dd>
<p><a href="#item_binmode"><code>binmode</code></a> sets <a href="#item_binmode"><code>binmode</code></a> on the underlying <code>IO</code> object, as documented
in <code>perldoc -f binmode</code>.</p>
</dd>
<dd>
<p><a href="#item_binmode"><code>binmode</code></a> accepts one optional parameter, which is the layer to be
passed on to the <a href="#item_binmode"><code>binmode</code></a> call.</p>
</dd>
</li>
</dl>
<p>
</p>
<hr />
<h1><a name="note">NOTE</a></h1>
<p>Some operating systems may perform <a href="#item_new"><code>IO::File::new()</code></a> or <a href="#item_open"><code>IO::File::open()</code></a>
on a directory without errors. This behavior is not portable and not
suggested for use. Using <a href="../../lib/Pod/perlfunc.html#item_opendir"><code>opendir()</code></a> and <a href="../../lib/Pod/perlfunc.html#item_readdir"><code>readdir()</code></a> or <code>IO::Dir</code> are
suggested instead.</p>
<p>
</p>
<hr />
<h1><a name="see_also">SEE ALSO</a></h1>
<p><a href="../../lib/Pod/perlfunc.html">the perlfunc manpage</a>,
<a href="../../lib/Pod/perlop.html#i_o_operators">I/O Operators in the perlop manpage</a>,
<a href="../../lib/IO/Handle.html">the IO::Handle manpage</a>,
<a href="../../lib/IO/Seekable.html">the IO::Seekable manpage</a>,
<a href="../../lib/IO/Dir.html">the IO::Dir manpage</a></p>
<p>
</p>
<hr />
<h1><a name="history">HISTORY</a></h1>
<p>Derived from FileHandle.pm by Graham Barr <<em><a href="mailto:gbarr@pobox.com">gbarr@pobox.com</a></em>>.</p>
</body>
</html>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?