?? read.html
字號:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta http-equiv="Content-Style-Type" content="text/css">
<link rel="up" title="FatFs" href="../00index_e.html">
<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
<title>FatFs - f_read</title>
</head>
<body>
<div class="para">
<h2>f_read</h2>
<p>The f_read function reads data from a file.</p>
<pre>
FRESULT f_read (
FIL* <em>FileObject</em>, /* Pointer to the file object structure */
void* <em>Buffer</em>, /* Pointer to the buffer to store read data */
UINT <em>ByteToRead</em>, /* Number of bytes to read */
UINT* <em>ByteRead</em> /* Pointer to the variable to return number of bytes read */
);
</pre>
</div>
<div class="para">
<h4>Parameters</h4>
<dl class="par">
<dt>FileObject</dt>
<dd>Pointer to the open file object.</dd>
<dt>Buffer</dt>
<dd>Pointer to the buffer to store read data</dd>
<dt>ByteToRead</dt>
<dd>Number of bytes to read in range of UINT.</dd>
<dt>ByteRead</dt>
<dd>Pointer to the UINT variable to return number of bytes read.</dd>
</dl>
</div>
<div class="para">
<h4>Return Values</h4>
<dl class="ret">
<dt>FR_OK (0)</dt>
<dd>The function succeeded.</dd>
<dt>FR_DENIED</dt>
<dd>The function denied due to the file has been opened in non-read mode.</dd>
<dt>FR_RW_ERROR</dt>
<dd>The function failed due to a disk error or an internal error.</dd>
<dt>FR_NOT_READY</dt>
<dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
<dt>FR_INVALID_OBJECT</dt>
<dd>The file object is invalid.</dd>
</dl>
</div>
<div class="para">
<h4>Description</h4>
<p>The file pointer of the file object increases in number of bytes read. After the function succeeded, <tt>*ByteRead</tt> should be checked to detect end of file. In case of <tt>*ByteRead < ByteToRead</tt>, it means the R/W pointer reached end of file during read operation.</p>
</div>
<div class="para">
<h4>References</h4>
<p><tt><a href="open.html">f_open</a>, <a href="gets.html">fgets</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a></tt></p>
</div>
<p class="foot"><a href="../00index_e.html">Return</a></p>
</body>
</html>
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -