write.html
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/write.html"> 8 <link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default"> 9 <title>FatFs - f_write</title> 10 </head> 11 12 <body> 13 14 <div class="para func"> 15 <h2>f_write</h2> 16 <p>The f_write writes data to a file.</p> 17 <pre> 18 FRESULT f_write ( 19 FIL* <span class="arg">fp</span>, <span class="c">/* [IN] Pointer to the file object structure */</span> 20 const void* <span class="arg">buff</span>, <span class="c">/* [IN] Pointer to the data to be written */</span> 21 UINT <span class="arg">btw</span>, <span class="c">/* [IN] Number of bytes to write */</span> 22 UINT* <span class="arg">bw</span> <span class="c">/* [OUT] Pointer to the variable to return number of bytes written */</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 structure.</dd> 32 <dt>buff</dt> 33 <dd>Pointer to the data to be written.</dd> 34 <dt>btw</dt> 35 <dd>Specifies number of bytes to write in range of <tt>UINT</tt> type.</dd> 36 <dt>bw</dt> 37 <dd>Pointer to the <tt>UINT</tt> variable that receives the number of bytes written. This value is always valid after the function call regardless of the function return code. If the return value is equal to <tt class="arg">btw</tt>, the function return code should be <tt>FR_OK</tt>.</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 write data to the file at the file offset pointed by 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> 58 </div> 59 60 61 <div class="para comp"> 62 <h4>QuickInfo</h4> 63 <p>Available when <tt><a href="config.html#fs_readonly">FF_FS_READONLY</a> == 0</tt>.</p> 64 </div> 65 66 67 <div class="para use"> 68 <h4>Example</h4> 69 <p>Refer to the example in <tt>f_open</tt>.</p> 70 </div> 71 72 73 <div class="para ref"> 74 <h4>See Also</h4> 75 <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> 76 </div> 77 78 <p class="foot"><a href="../00index_e.html">Return</a></p> 79 </body> 80 </html>