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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Binary-safe file write</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div 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"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>fwrite</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$handle</tt></span> , <span class="methodparam"><span class="type">string</span> <tt class="parameter">$string</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$length</tt></span> ] )</div> <p class="simpara"> <b>fwrite()</b> writes the contents of <i><tt class="parameter">string</tt></i> to the file stream pointed to by <i><tt class="parameter">handle</tt></i>. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">handle</tt></i></span> <dd> <p class="para">A file system pointer <a href="language.types.resource.html" class="type resource">resource</a>that is typically created using <a href="function.fopen.html" class="function">fopen()</a>.</p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">string</tt></i></span> <dd> <p class="para"> The string that is to be written. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">length</tt></i></span> <dd> <p class="para"> If the <i><tt class="parameter">length</tt></i> argument is given, writing will stop after <i><tt class="parameter">length</tt></i> bytes have been written or the end of <i><tt class="parameter">string</tt></i> is reached, whichever comes first. </p> <p class="para"> Note that if the <i><tt class="parameter">length</tt></i> 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 <i><tt class="parameter">string</tt></i>. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="simpara"> <b>fwrite()</b> returns the number of bytes written, or <b><tt>FALSE</tt></b> on error. </p> </div> <div class="refsect1 notes"> <h3 class="title">Notes</h3> <blockquote><p><b class="note">Note</b>: On systems which differentiate between binary and text files (i.e. Windows) the file must be opened with 'b' included in <a href="function.fopen.html" class="function">fopen()</a> mode parameter. <br /> </p></blockquote> <blockquote><p><b class="note">Note</b>: If <i><tt class="parameter">handle</tt></i> was <a href="function.fopen.html" class="function">fopen()</a>ed in append mode, <b>fwrite()</b>s are atomic (unless the size of <i><tt class="parameter">string</tt></i> 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 <a href="function.flock.html" class="function">flock()</a> a resource before calling <b>fwrite()</b>; all of the data will be written without interruption. <br /> </p></blockquote> <blockquote><p><b class="note">Note</b>: If writing twice to the file pointer, then the data will be appended to the end of the file content, meaning that the example below wouldn't work as expected: <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">$fp</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// the content of 'data.txt' is now 123 and not 23!<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <br /> </p></blockquote> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 A simple <b>fwrite()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$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">$filename</span><span style="color: #007700">, </span><span style="color: #DD0000">'a'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Cannot open file ($filename)"</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">$somecontent</span><span style="color: #007700">) === </span><span style="color: #0000BB">FALSE</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Cannot write to file ($filename)"</span><span style="color: #007700">;<br /> exit;<br /> }<br /><br /> echo </span><span style="color: #DD0000">"Success, wrote ($somecontent) to file ($filename)"</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 $filename 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"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.fread.html" class="function" rel="rdfs-seeAlso">fread()</a></li> <li class="member"><a href="function.fopen.html" class="function" rel="rdfs-seeAlso">fopen()</a></li> <li class="member"><a href="function.fsockopen.html" class="function" rel="rdfs-seeAlso">fsockopen()</a></li> <li class="member"><a href="function.popen.html" class="function" rel="rdfs-seeAlso">popen()</a></li> <li class="member"><a href="function.file-get-contents.html" class="function" rel="rdfs-seeAlso">file_get_contents()</a></li> </ul> </p> </div></div><hr /><div 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>⌨️ 快捷键说明
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