<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Binary-safe file write</title>
</head>
<body><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="function.ftruncate.html">ftruncate</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.glob.html">glob</a></div>
<div class="up"><a href="ref.filesystem.html">Filesystem Functions</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="function.fwrite" class="refentry">
<div class="refnamediv">
<h1 class="refname">fwrite</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">fwrite</span> — <span class="dc-title">Binary-safe file write</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.fwrite-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">int</span> <span class="methodname"><strong>fwrite</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$handle</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$string</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code></span>
] )</div>
<p class="simpara">
<span class="function"><strong>fwrite()</strong></span> writes the contents of
<em><code class="parameter">string</code></em> to the file stream pointed to by
<em><code class="parameter">handle</code></em>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.fwrite-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">handle</code></em></span>
<dd>
<p class="para">A file system pointer <span class="type"><a href="language.types.resource.html" class="type resource">resource</a></span>
that is typically created using <span class="function"><a href="function.fopen.html" class="function">fopen()</a></span>.</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">string</code></em></span>
<dd>
<p class="para">
The string that is to be written.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">length</code></em></span>
<dd>
<p class="para">
If the <em><code class="parameter">length</code></em> argument is given, writing will
stop after <em><code class="parameter">length</code></em> bytes have been written or
the end of <em><code class="parameter">string</code></em> is reached, whichever comes
first.
</p>
<p class="para">
Note that if the <em><code class="parameter">length</code></em> argument is given,
then the <a href="info.configuration.html#ini.magic-quotes-runtime" class="link">magic_quotes_runtime</a>
configuration option will be ignored and no slashes will be
stripped from <em><code class="parameter">string</code></em>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.fwrite-returnvalues">
<h3 class="title">Return Values</h3>
<p class="simpara">
<span class="function"><strong>fwrite()</strong></span> returns the number of bytes
written, or <strong><code>FALSE</code></strong> on error.
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.fwrite-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Writing to a network stream may end before the whole string is written.
Return value of <span class="function"><strong>fwrite()</strong></span> may be checked:
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">fwrite_stream</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">$string</span><span style="color: #007700">) {<br /> for (</span><span style="color: #0000BB">$written </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">; </span><span style="color: #0000BB">$written </span><span style="color: #007700">< </span><span style="color: #0000BB">strlen</span><span style="color: #007700">(</span><span style="color: #0000BB">$string</span><span style="color: #007700">); </span><span style="color: #0000BB">$written </span><span style="color: #007700">+= </span><span style="color: #0000BB">$fwrite</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$fwrite </span><span style="color: #007700">= </span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">substr</span><span style="color: #007700">(</span><span style="color: #0000BB">$string</span><span style="color: #007700">, </span><span style="color: #0000BB">$written</span><span style="color: #007700">));<br /> if (</span><span style="color: #0000BB">$fwrite </span><span style="color: #007700">=== </span><span style="color: #0000BB">false</span><span style="color: #007700">) {<br /> return </span><span style="color: #0000BB">$written</span><span style="color: #007700">;<br /> }<br /> }<br /> return </span><span style="color: #0000BB">$written</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
On systems which differentiate between binary and text files
(i.e. Windows) the file must be opened with 'b' included in
<span class="function"><a href="function.fopen.html" class="function">fopen()</a></span> mode parameter.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
If <em><code class="parameter">handle</code></em> was <span class="function"><a href="function.fopen.html" class="function">fopen()</a></span>ed in
append mode, <span class="function"><strong>fwrite()</strong></span>s are atomic (unless the size of
<em><code class="parameter">string</code></em> exceeds the filesystem's block size, on some
platforms, and as long as the file is on a local filesystem). That is,
there is no need to <span class="function"><a href="function.flock.html" class="function">flock()</a></span> a resource before calling
<span class="function"><strong>fwrite()</strong></span>; all of the data will be written without
interruption.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
If writing twice to the file pointer, then the data will be appended to
the end of the file content:
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'data.txt'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'1'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'23'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// the content of 'data.txt' is now 123 and not 23!<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</p>
</p></blockquote>
</div>
<div class="refsect1 examples" id="refsect1-function.fwrite-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-2397">
<p><strong>Example #1 A simple <span class="function"><strong>fwrite()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$filename </span><span style="color: #007700">= </span><span style="color: #DD0000">'test.txt'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$somecontent </span><span style="color: #007700">= </span><span style="color: #DD0000">"Add this to the file\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// Let's make sure the file exists and is writable first.<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">is_writable</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">)) {<br /><br /> </span><span style="color: #FF8000">// In our example we're opening $filename in append mode.<br /> // The file pointer is at the bottom of the file hence<br /> // that's where $somecontent will go when we fwrite() it.<br /> </span><span style="color: #007700">if (!</span><span style="color: #0000BB">$handle </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">, </span><span style="color: #DD0000">'a'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Cannot open file (</span><span style="color: #0000BB">$filename</span><span style="color: #DD0000">)"</span><span style="color: #007700">;<br /> exit;<br /> }<br /><br /> </span><span style="color: #FF8000">// Write $somecontent to our opened file.<br /> </span><span style="color: #007700">if (</span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$handle</span><span style="color: #007700">, </span><span style="color: #0000BB">$somecontent</span><span style="color: #007700">) === </span><span style="color: #0000BB">FALSE</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Cannot write to file (</span><span style="color: #0000BB">$filename</span><span style="color: #DD0000">)"</span><span style="color: #007700">;<br /> exit;<br /> }<br /><br /> echo </span><span style="color: #DD0000">"Success, wrote (</span><span style="color: #0000BB">$somecontent</span><span style="color: #DD0000">) to file (</span><span style="color: #0000BB">$filename</span><span style="color: #DD0000">)"</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$handle</span><span style="color: #007700">);<br /><br />} else {<br /> echo </span><span style="color: #DD0000">"The file </span><span style="color: #0000BB">$filename</span><span style="color: #DD0000"> is not writable"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.fwrite-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.fread.html" class="function" rel="rdfs-seeAlso">fread()</a> - Binary-safe file read</span></li>
<li class="member"> <span class="function"><a href="function.fopen.html" class="function" rel="rdfs-seeAlso">fopen()</a> - Opens file or URL</span></li>
<li class="member"> <span class="function"><a href="function.fsockopen.html" class="function" rel="rdfs-seeAlso">fsockopen()</a> - Open Internet or Unix domain socket connection</span></li>
<li class="member"> <span class="function"><a href="function.popen.html" class="function" rel="rdfs-seeAlso">popen()</a> - Opens process file pointer</span></li>
<li class="member"> <span class="function"><a href="function.file-get-contents.html" class="function" rel="rdfs-seeAlso">file_get_contents()</a> - Reads entire file into a string</span></li>
</ul>
</p>
</div>
</div><hr /><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="function.ftruncate.html">ftruncate</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.glob.html">glob</a></div>
<div class="up"><a href="ref.filesystem.html">Filesystem Functions</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div></body></html>
