fatfs/doc/en/printf.html

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   9 <title>FatFs - f_printf</title>
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  12 <body>
  13
  14 <div class="para func">
  15 <h2>f_printf</h2>
  16 <p>The f_printf function writes formatted string to the file.</p>
  17 <pre>
  18 int f_printf (
  19   FIL* <span class="arg">fp</span>,          <span class="c">/* [IN] File object */</span>
  20   const TCHAR* <span class="arg">fmt</span>, <span class="c">/* [IN] Format stirng */</span>
  21   ...
  22 );
  23 </pre>
  24 </div>
  25
  26 <div class="para arg">
  27 <h4>Parameters</h4>
  28 <dl class="par">
  29 <dt>fp</dt>
  30 <dd>Pointer to the open file object structure.</dd>
  31 <dt>fmt</dt>
  32 <dd>Pointer to the null terminated format string. The terminator charactor will not be written.</dd>
  33 <dt>...</dt>
  34 <dd>Optional arguments...</dd>
  35
  36 </dl>
  37 </div>
  38
  39
  40 <div class="para ret">
  41 <h4>Return Values</h4>
  42 <p>When the function succeeded, it returns number of characters written. If the function could not write the generated string to the file due to disk full or an error, <tt>EOF (-1)</tt> will be returned.</p>
  43 </div>
  44
  45
  46 <div class="para desc">
  47 <h4>Description</h4>
  48 <p>The format control directive is a sub-set of standard library shown as follos:</p>
  49 <ul>
  50 <li>Type: <tt>c C s S d D u U x X b B</tt></li>
  51 <li>Size: <tt>l L</tt></li>
  52 <li>Flag: <tt>0 -</tt></li>
  53 </ul>
  54 </div>
  55
  56
  57 <div class="para comp">
  58 <h4>QuickInfo</h4>
  59 <p>This is a wrapper function of <a href="write.html"><tt>f_write</tt></a> function. Available when <tt>_FS_READONLY == 0</tt> and <tt>_USE_STRFUNC</tt> is 1 or 2. When it is set to 2, <tt>'\n'</tt>s contained in the output are converted to <tt>'\r'+'\n'</tt>.</p>
  60 <p>When FatFs is configured to Unicode API (<tt>_LFN_UNICODE == 1</tt>), data types on the srting fuctions, <tt>f_putc</tt>, <tt>f_puts</tt>, <tt>f_printf</tt> and <tt>f_gets</tt> function, is also switched to Unicode. The character encoding on the file to be read/written via those functions is selected by <tt>_STRF_ENCODE</tt> option.</p>
  61 </div>
  62
  63
  64 <div class="para use">
  65 <h4>Example</h4>
  66 <pre>
  67     f_printf(&amp;fil, "%d", 1234);            <span class="c">/* "1234" */</span>
  68     f_printf(&amp;fil, "%6d,%3d%%", -200, 5);  <span class="c">/* "  -200,  5%" */</span>
  69     f_printf(&amp;fil, "%ld", 12345L);         <span class="c">/* "12345" */</span>
  70     f_printf(&amp;fil, "%06d", 25);            <span class="c">/* "000025" */</span>
  71     f_printf(&amp;fil, "%06d", -25);           <span class="c">/* "000-25" */</span>
  72     f_printf(&amp;fil, "%-6d", 25);            <span class="c">/* "25    " */</span>
  73     f_printf(&amp;fil, "%u", -1);              <span class="c">/* "65535" or "4294967295" */</span>
  74     f_printf(&amp;fil, "%04x", 0xAB3);         <span class="c">/* "0ab3" */</span>
  75     f_printf(&amp;fil, "%08LX", 0x123ABCL);    <span class="c">/* "00123ABC" */</span>
  76     f_printf(&amp;fil, "%016b", 0x550F);       <span class="c">/* "0101010100001111" */</span>
  77     f_printf(&amp;fil, "%s", "String");        <span class="c">/* "String" */</span>
  78     f_printf(&amp;fil, "%8s", "abc");          <span class="c">/* "     abc" */</span>
  79     f_printf(&amp;fil, "%-8s", "abc");         <span class="c">/* "abc     " */</span>
  80     f_printf(&amp;fil, "%c", 'a');             <span class="c">/* "a" */</span>
  81     f_printf(&amp;fil, "%f", 10.0);            <span class="c">/* f_printf lacks floating point support */</span>
  82 </pre>
  83 </div>
  84
  85
  86 <div class="para ref">
  87 <h4>See Also</h4>
  88 <p><tt><a href="open.html">f_open</a>, <a href="putc.html">f_putc</a>, <a href="puts.html">f_puts</a>, <a href="gets.html">f_gets</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a></tt></p>
  89 </div>
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