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Diffstat (limited to 'fatfs/documents/doc/printf.html')
| -rw-r--r-- | fatfs/documents/doc/printf.html | 61 |
1 files changed, 39 insertions, 22 deletions
diff --git a/fatfs/documents/doc/printf.html b/fatfs/documents/doc/printf.html index 82be70c..eb64e8d 100644 --- a/fatfs/documents/doc/printf.html +++ b/fatfs/documents/doc/printf.html @@ -39,7 +39,7 @@ int f_printf ( <div class="para ret"> <h4>Return Values</h4> -<p>When the string was written successfuly, it returns number of character encoding units written to the file. When the function failed due to disk full or any error, an <tt>EOF (-1)</tt> will be returned.</p> +<p>When the string was written successfuly, it returns number of character encoding units written to the file. When the function failed due to disk full or an error, a negative value will be returned.</p> </div> @@ -47,14 +47,30 @@ int f_printf ( <h4>Description</h4> <p>The format control directive is a sub-set of standard library shown as follows:</p> <pre> - %[flag][width][type] + %[flag][width][precision][size]type </pre> <dl> -<dt>flag</dt><dd>Padding options. A <tt>-</tt> specifies left justified. A <tt>0</tt> specifies zero padded.</dd> -<dt>width</dt><dd>Minimum width of the field, <tt>1-99</tt> or <tt>*</tt>. If the width of generated string is less than the specified value, rest field is padded with white spaces or zeros. An <tt>*</tt> specifies the value comes from an argument in int type.</dd> -<dt>type</dt><dd><tt>c s d u o x b</tt> and prefix <tt>l</tt> specify type of the argument, character, string, signed integer in decimal, unsigned integer in decimal, unsigned integer in octal, unsigned integer in hexdecimal and unsigned integer in binary respectively. If <tt>sizeof (long)</tt> is greater than <tt>sizeof (int)</tt> (this is typical of 8/16-bit systems), a prefix <tt>l</tt> needs to be explicitly specified for long integer argument. These characters except for <tt>x</tt> are case insensitive.</dd> +<dt>flag</dt><dd>Padding option. A <tt>-</tt> specifies left-aligned. A <tt>0</tt> specifies zero padded. The default setting is in right-aligned and space padded.</dd> +<dt>width</dt><dd>Minimum width of the field, <tt>1-99</tt> or <tt>*</tt>. If the width of generated string is less than the minimum width, rest field is padded with spaces or zeros. An <tt>*</tt> specifies the value comes from an argument in int type. The default setting is zero.</dd> +<dt>precision</dt><dd>Specifies number of fractional digits or maximum width of string, <tt>.0-.99</tt> or <tt>.*</tt>. If the number is omitted, it is same as <tt>.0</tt>. Default setting is 6 for number and no limit for string.</dd> +<dt>size</dt><dd>Specifies size of integer argument, <tt>l</tt>(long) and <tt>ll</tt>(long long). If <tt>sizeof (long) == sizeof (int)</tt> is true (this is typical of 32-bit systems), prefix <tt>l</tt> can be omitted for long integer argument. The default size is int for integer argument and floating point argument is always assumed double as the default argument promotion.</dd> +<dt>type</dt><dd>Specifies type of the output format and the argument as shown below. The length of generated string is in assumtion of int is 32-bit. +<table class="lst1"> +<tr><th>Type</th><th>Format</th><th>Argument</th><th>Length</th></tr> +<tr><td><tt>c</tt></td><td>Character</td><td rowspan="6"><tt>int</tt>,<br><tt>long</tt>,<br><tt>long long</tt></td><td>1 character.</td></tr> +<tr><td><tt>d</tt></td><td>Signed decimal</td><td>1 to 11 (20 for ll) characters.</td></tr> +<tr><td><tt>u</tt></td><td>Unsigned decimal</td><td>1 to 10 (20 for ll) characters.</td></tr> +<tr><td><tt>o</tt></td><td>Unsigned octal</td><td>1 to 11 (22 for ll) characters.</td></tr> +<tr><td><tt>x X</tt></td><td>Unsigned hexdecimal</td><td>1 to 8 (16 for ll) characters.</td></tr> +<tr><td><tt>b</tt></td><td>Unsigned binary</td><td>1 to 32 characters. Limited to lower 32 digits when ll is specified.</td></tr> +<tr><td><tt>s</tt></td><td>String</td><td><tt>TCHAR*</tt></td><td>As input string. Null pointer generates a null string.</td></tr> +<tr><td><tt>f</tt></td><td>Floating point<br>(decimal)</td><td rowspan="2"><tt>double</tt></td><td>1 to 31 characters. If the number of characters exceeds 31, it writes <tt>"±OV"</tt>. Not a number and infinite write <tt>"NaN"</tt> and <tt>"±INF"</tt>.</td></tr> +<tr><td><tt>e E</tt></td><td>Floating point<br>(e notation)</td><td>4 to 31 characters. If the number of characters exceeds 31 or exponent exceeds +99, it writes <tt>"±OV"</tt>.</td></tr> +</table> +</dd> </dl> <p>When FatFs is configured for Unicode API (<tt><a href="config.html#lfn_unicode">FF_LFN_UNICODE</a> >= 1</tt>), character encoding on the string 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 Unicode characters in multiple encoding unit, such as surrogate pair and multi-byte sequence, should not be divided into two function calls, or the character will be lost. The character encoding <em>on the file</em> to be written via this function is selected by <tt><a href="config.html#strf_encode">FF_STRF_ENCODE</a></tt>. The characters with wrong encoding or invalid for the output encoding will be lost.</p> +<p>If <tt>sprintf</tt> is used in the project and code conversion is not needed, <tt>f_write</tt> with <tt>sprintf</tt> will be efficient in code size and performance rather than <tt>f_printf</tt>.</p> </div> @@ -67,23 +83,24 @@ int f_printf ( <div class="para use"> <h4>Example</h4> <pre> - <em>f_printf</em>(&fil, "%d", 1234); <span class="c">/* "1234" */</span> - <em>f_printf</em>(&fil, "%6d,%3d%%", -200, 5); <span class="c">/* " -200, 5%" */</span> - <em>f_printf</em>(&fil, "%ld", 12345L); <span class="c">/* "12345" */</span> - <em>f_printf</em>(&fil, "%06d", 25); <span class="c">/* "000025" */</span> - <em>f_printf</em>(&fil, "%06d", -25); <span class="c">/* "000-25" */</span> - <em>f_printf</em>(&fil, "%*d", 5, 100); <span class="c">/* " 100" */</span> - <em>f_printf</em>(&fil, "%-6d", 25); <span class="c">/* "25 " */</span> - <em>f_printf</em>(&fil, "%u", -1); <span class="c">/* "65535" or "4294967295" */</span> - <em>f_printf</em>(&fil, "%04x", 0xAB3); <span class="c">/* "0ab3" */</span> - <em>f_printf</em>(&fil, "%08lX", 0x123ABCL); <span class="c">/* "00123ABC" */</span> - <em>f_printf</em>(&fil, "%04o", 255); <span class="c">/* "0377" */</span> - <em>f_printf</em>(&fil, "%016b", 0x550F); <span class="c">/* "0101010100001111" */</span> - <em>f_printf</em>(&fil, "%s", "String"); <span class="c">/* "String" */</span> - <em>f_printf</em>(&fil, "%8s", "abc"); <span class="c">/* " abc" */</span> - <em>f_printf</em>(&fil, "%-8s", "abc"); <span class="c">/* "abc " */</span> - <em>f_printf</em>(&fil, "%c", 'a'); <span class="c">/* "a" */</span> - <em>f_printf</em>(&fil, "%f", 10.0); <span class="c">/* f_printf lacks floating point support */</span> + <em>f_printf</em>(fp, "%d", 1234); <span class="c">/* "1234" */</span> + <em>f_printf</em>(fp, "%6d,%3d%%", -200, 5); <span class="c">/* " -200, 5%" */</span> + <em>f_printf</em>(fp, "%-6u", 100); <span class="c">/* "100 " */</span> + <em>f_printf</em>(fp, "%ld", 12345678); <span class="c">/* "12345678" */</span> + <em>f_printf</em>(fp, "%llu", 0x100000000); <span class="c">/* "4294967296" (<a href="config.html#print_lli">FF_PRINT_LLI</a>) */</span> + <em>f_printf</em>(fp, "%lld", -1LL); <span class="c">/* "-1" (FF_PRINT_LLI) */</span> + <em>f_printf</em>(fp, "%04x", 0xA3); <span class="c">/* "00a3" */</span> + <em>f_printf</em>(fp, "%08lX", 0x123ABC); <span class="c">/* "00123ABC" */</span> + <em>f_printf</em>(fp, "%016b", 0x550F); <span class="c">/* "0101010100001111" */</span> + <em>f_printf</em>(fp, "%*d", 6, 100); <span class="c">/* " 100" */</span> + <em>f_printf</em>(fp, "%s", "abcdefg"); <span class="c">/* "abcdefg" */</span> + <em>f_printf</em>(fp, "%5s", "abc"); <span class="c">/* " abc" */</span> + <em>f_printf</em>(fp, "%-5s", "abc"); <span class="c">/* "abc " */</span> + <em>f_printf</em>(fp, "%.5s", "abcdefg"); <span class="c">/* "abcde" */</span> + <em>f_printf</em>(fp, "%-5.2s", "abcdefg"); <span class="c">/* "ab " */</span> + <em>f_printf</em>(fp, "%c", 'a'); <span class="c">/* "a" */</span> + <em>f_printf</em>(fp, "%12f", 10.0); <span class="c">/* " 10.000000" (<a href="config.html#print_fp">FF_PRINT_FLOAT</a>) */</span> + <em>f_printf</em>(fp, "%.4E", 123.45678); <span class="c">/* "1.2346E+02" (FF_PRINT_FLOAT) */</span> </pre> </div> |