1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 2<html lang="en"> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 5<meta http-equiv="Content-Style-Type" content="text/css"> 6<link rel="up" title="FatFs" href="../00index_e.html"> 7<link rel="alternate" hreflang="ja" title="Japanese" href="../ja/read.html"> 8<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default"> 9<title>FatFs - f_read</title> 10</head> 11 12<body> 13 14<div class="para func"> 15<h2>f_read</h2> 16<p>The f_read function reads data from a file.</p> 17<pre> 18FRESULT f_read ( 19 FIL* <span class="arg">fp</span>, <span class="c">/* [IN] File object */</span> 20 void* <span class="arg">buff</span>, <span class="c">/* [OUT] Buffer to store read data */</span> 21 UINT <span class="arg">btr</span>, <span class="c">/* [IN] Number of bytes to read */</span> 22 UINT* <span class="arg">br</span> <span class="c">/* [OUT] Number of bytes read */</span> 23); 24</pre> 25</div> 26 27<div class="para arg"> 28<h4>Parameters</h4> 29<dl class="par"> 30<dt>fp</dt> 31<dd>Pointer to the open file object.</dd> 32<dt>buff</dt> 33<dd>Pointer to the buffer to store the read data.</dd> 34<dt>btr</dt> 35<dd>Number of bytes to read in range of <tt>UINT</tt> type.</dd> 36<dt>br</dt> 37<dd>Pointer to the <tt>UINT</tt> variable that receives number of bytes read. This value is always valid after the function call regardless of the function return code.</dd> 38</dl> 39</div> 40 41 42<div class="para ret"> 43<h4>Return Values</h4> 44<p> 45<a href="rc.html#ok">FR_OK</a>, 46<a href="rc.html#de">FR_DISK_ERR</a>, 47<a href="rc.html#ie">FR_INT_ERR</a>, 48<a href="rc.html#dn">FR_DENIED</a>, 49<a href="rc.html#io">FR_INVALID_OBJECT</a>, 50<a href="rc.html#tm">FR_TIMEOUT</a> 51</p> 52</div> 53 54 55<div class="para desc"> 56<h4>Description</h4> 57<p>The function starts to read data from the file at the position pointed by the read/write pointer. The read/write pointer advances as number of bytes read. After the function succeeded, <tt class="arg">*br</tt> should be checked to detect end of the file. In case of <tt class="arg">*br</tt> < <tt class="arg">btr</tt>, it means the read/write pointer reached end of the file during read operation.</p> 58</div> 59 60 61<div class="para comp"> 62<h4>QuickInfo</h4> 63<p>Always available.</p> 64</div> 65 66 67<div class="para ref"> 68<h4>See Also</h4> 69<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> 70</div> 71 72<p class="foot"><a href="../00index_e.html">Return</a></p> 73</body> 74</html> 75