<!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="alternate" hreflang="ja" title="Japanese" href="../ja/write.html"> <link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default"> <title>FatFs - f_write</title> </head> <body> <div class="para func"> <h2>f_write</h2> <p>The f_write writes data to a file.</p> <pre> FRESULT f_write ( FIL* <span class="arg">fp</span>, <span class="c">/* [IN] Pointer to the file object structure */</span> const void* <span class="arg">buff</span>, <span class="c">/* [IN] Pointer to the data to be written */</span> UINT <span class="arg">btw</span>, <span class="c">/* [IN] Number of bytes to write */</span> UINT* <span class="arg">bw</span> <span class="c">/* [OUT] Pointer to the variable to return number of bytes written */</span> ); </pre> </div> <div class="para arg"> <h4>Parameters</h4> <dl class="par"> <dt>fp</dt> <dd>Pointer to the open file object structure.</dd> <dt>buff</dt> <dd>Pointer to the data to be written.</dd> <dt>btw</dt> <dd>Specifies number of bytes to write in range of <tt>UINT</tt> type.</dd> <dt>bw</dt> <dd>Pointer to the <tt>UINT</tt> variable to return the number of bytes written. The value is always valid after the function call regardless of the result code.</dd> </dl> </div> <div class="para ret"> <h4>Return Values</h4> <p> <a href="rc.html#ok">FR_OK</a>, <a href="rc.html#de">FR_DISK_ERR</a>, <a href="rc.html#ie">FR_INT_ERR</a>, <a href="rc.html#dn">FR_DENIED</a>, <a href="rc.html#io">FR_INVALID_OBJECT</a>, <a href="rc.html#tm">FR_TIMEOUT</a> </p> </div> <div class="para desc"> <h4>Description</h4> <p>The function starts to write data to the file at the position pointed by the read/write pointer. The read/write pointer advances as number of bytes written. After the function succeeded, <tt class="arg">*bw</tt> should be checked to detect the disk full. In case of <tt class="arg">*bw</tt> < <tt class="arg">btw</tt>, it means the volume got full during the write operation. The function can take a time when the volume is full or close to full.</p> </div> <div class="para comp"> <h4>QuickInfo</h4> <p>Available when <tt>_FS_READONLY == 0</tt>.</p> </div> <div class="para ref"> <h4>See Also</h4> <p><tt><a href="open.html">f_open</a>, <a href="read.html">f_read</a>, <a href="putc.html">fputc</a>, <a href="puts.html">fputs</a>, <a href="printf.html">fprintf</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>