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<!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. The value is always valid after the function call regardless of the result.</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_DISK_ERR</dt> <dd>The function failed due to an error in the disk function.</dd> <dt>FR_INT_ERR</dt> <dd>The function failed due to a wrong FAT structure 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 the end of file. In case of <tt>*ByteRead < ByteToRead</tt>, it means the R/W pointer reached end of the file during read operation.</p> </div> <div class="para"> <h4>QuickInfo</h4> <p>Always available.</p> </div> <div class="para"> <h4>See Also</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>