1FWPRINTF(P) POSIX Programmer's Manual FWPRINTF(P)
2
6 fwprintf, swprintf, wprintf - print formatted wide-character output
7
9 #include <stdio.h>
10 #include <wchar.h>
11 int fwprintf(FILE *restrict stream, const wchar_t *restrict format,
13 ...);
14 int swprintf(wchar_t *restrict ws, size_t n,
15 const wchar_t *restrict format, ...);
16 int wprintf(const wchar_t *restrict format, ...);
17
20 The fwprintf() function shall place output on the named output stream.
21 The wprintf() function shall place output on the standard output stream
22 stdout. The swprintf() function shall place output followed by the null
23 wide character in consecutive wide characters starting at *ws; no more
24 than n wide characters shall be written, including a terminating null
25 wide character, which is always added (unless n is zero).
26 Each of these functions shall convert, format, and print its arguments
28 under control of the format wide-character string. The format is com‐
29 posed of zero or more directives: ordinary wide-characters, which are
30 simply copied to the output stream, and conversion specifications, each
31 of which results in the fetching of zero or more arguments. The results
32 are undefined if there are insufficient arguments for the format. If
33 the format is exhausted while arguments remain, the excess arguments
34 are evaluated but are otherwise ignored.
35 Conversions can be applied to the nth argument after the format in the
37 argument list, rather than to the next unused argument. In this case,
38 the conversion specifier wide character % (see below) is replaced by
39 the sequence "%n$" , where n is a decimal integer in the range
40 [1,{NL_ARGMAX}], giving the position of the argument in the argument
41 list. This feature provides for the definition of format wide-character
42 strings that select arguments in an order appropriate to specific lan‐
43 guages (see the EXAMPLES section).
44 The format can contain either numbered argument specifications (that
46 is, "%n$" and "*m$"), or unnumbered argument conversion specifications
47 (that is, % and * ), but not both. The only exception to this is that
48 %% can be mixed with the "%n$" form. The results of mixing numbered and
49 unnumbered argument specifications in a format wide-character string
50 are undefined. When numbered argument specifications are used, specify‐
51 ing the Nth argument requires that all the leading arguments, from the
52 first to the (N-1)th, are specified in the format wide-character
53 string.
54 In format wide-character strings containing the "%n$" form of conver‐
56 sion specification, numbered arguments in the argument list can be ref‐
57 erenced from the format wide-character string as many times as
58 required.
59 In format wide-character strings containing the % form of conversion
61 specification, each argument in the argument list shall be used exactly
62 once.
63 All forms of the fwprintf() function allow for the insertion of a
65 locale-dependent radix character in the output string, output as a
66 wide-character value. The radix character is defined in the program's
67 locale (category LC_NUMERIC ). In the POSIX locale, or in a locale
68 where the radix character is not defined, the radix character shall
69 default to a period ( '.' ).
70 Each conversion specification is introduced by the '%' wide character
72 or by the wide-character sequence "%n$", after which the following
73 appear in sequence:
74 * Zero or more flags (in any order), which modify the meaning of the
76 conversion specification.
77 * An optional minimum field width. If the converted value has fewer
79 wide characters than the field width, it shall be padded with spaces
80 by default on the left; it shall be padded on the right, if the
81 left-adjustment flag ( '-' ), described below, is given to the field
82 width. The field width takes the form of an asterisk ( '*' ),
83 described below, or a decimal integer.
84 * An optional precision that gives the minimum number of digits to
86 appear for the d , i , o , u , x , and X conversion specifiers; the
87 number of digits to appear after the radix character for the a , A ,
88 e , E , f , and F conversion specifiers; the maximum number of sig‐
89 nificant digits for the g and G conversion specifiers; or the maxi‐
90 mum number of wide characters to be printed from a string in the s
91 conversion specifiers. The precision takes the form of a period (
92 '.' ) followed either by an asterisk ( '*' ), described below, or an
93 optional decimal digit string, where a null digit string is treated
94 as 0. If a precision appears with any other conversion wide charac‐
95 ter, the behavior is undefined.
96 * An optional length modifier that specifies the size of the argument.
98 * A conversion specifier wide character that indicates the type of
100 conversion to be applied.
101 A field width, or precision, or both, may be indicated by an asterisk (
103 '*' ). In this case an argument of type int supplies the field width or
104 precision. Applications shall ensure that arguments specifying field
105 width, or precision, or both appear in that order before the argument,
106 if any, to be converted. A negative field width is taken as a '-' flag
107 followed by a positive field width. A negative precision is taken as if
108 the precision were omitted. In format wide-character strings con‐
109 taining the "%n$" form of a conversion specification, a field width or
110 precision may be indicated by the sequence "*m$", where m is a decimal
111 integer in the range [1,{NL_ARGMAX}] giving the position in the argu‐
112 ment list (after the format argument) of an integer argument containing
113 the field width or precision, for example:
114 wprintf(L"%1$d:%2$.*3$d:%4$.*3$d\n", hour, min, precision, sec);
117 The flag wide characters and their meanings are:
119 ' The integer portion of the result of a decimal conversion ( %i ,
121 %d , %u , %f , %F , %g , or %G ) shall be formatted with thou‐
122 sands' grouping wide characters. For other conversions, the
123 behavior is undefined. The numeric grouping wide character is
124 used.
125 - The result of the conversion shall be left-justified within the
127 field. The conversion shall be right-justified if this flag is
128 not specified.
129 + The result of a signed conversion shall always begin with a sign
131 ( '+' or '-' ). The conversion shall begin with a sign only when
132 a negative value is converted if this flag is not specified.
133 <space>
135 If the first wide character of a signed conversion is not a
136 sign, or if a signed conversion results in no wide characters, a
137 <space> shall be prefixed to the result. This means that if the
138 <space> and '+' flags both appear, the <space> flag shall be
139 ignored.
140 # Specifies that the value is to be converted to an alternative
142 form. For o conversion, it increases the precision (if neces‐
143 sary) to force the first digit of the result to be 0. For x or X
144 conversion specifiers, a non-zero result shall have 0x (or 0X)
145 prefixed to it. For a , A , e , E , f , F , g , and G conversion
146 specifiers, the result shall always contain a radix character,
147 even if no digits follow it. Without this flag, a radix charac‐
148 ter appears in the result of these conversions only if a digit
149 follows it. For g and G conversion specifiers, trailing zeros
150 shall not be removed from the result as they normally are. For
151 other conversion specifiers, the behavior is undefined.
152 0 For d , i , o , u , x , X , a , A , e , E , f , F , g , and G
154 conversion specifiers, leading zeros (following any indication
155 of sign or base) are used to pad to the field width; no space
156 padding is performed. If the '0' and '-' flags both appear, the
157 '0' flag shall be ignored. For d , i , o , u , x , and X conver‐
158 sion specifiers, if a precision is specified, the '0' flag shall
159 be ignored. If the '0' and '" flags both appear, the grouping
160 wide characters are inserted before zero padding. For other con‐
161 versions, the behavior is undefined.
162 The length modifiers and their meanings are:
165 hh Specifies that a following d , i , o , u , x , or X conversion
167 specifier applies to a signed char or unsigned char argument
168 (the argument will have been promoted according to the integer
169 promotions, but its value shall be converted to signed char or
170 unsigned char before printing); or that a following n conversion
171 specifier applies to a pointer to a signed char argument.
172 h Specifies that a following d , i , o , u , x , or X conversion
174 specifier applies to a short or unsigned short argument (the
175 argument will have been promoted according to the integer promo‐
176 tions, but its value shall be converted to short or unsigned
177 short before printing); or that a following n conversion speci‐
178 fier applies to a pointer to a short argument.
179 l (ell)
181 Specifies that a following d , i , o , u , x , or X conversion
182 specifier applies to a long or unsigned long argument; that a
183 following n conversion specifier applies to a pointer to a long
184 argument; that a following c conversion specifier applies to a
185 wint_t argument; that a following s conversion specifier applies
186 to a pointer to a wchar_t argument; or has no effect on a fol‐
187 lowing a , A , e , E , f , F , g , or G conversion specifier.
188 ll (ell-ell)
190 Specifies that a following d , i , o , u , x , or X conversion
192 specifier applies to a long long or unsigned long long argument;
193 or that a following n conversion specifier applies to a pointer
194 to a long long argument.
195 j Specifies that a following d , i , o , u , x , or X conversion
197 specifier applies to an intmax_t or uintmax_t argument; or that
198 a following n conversion specifier applies to a pointer to an
199 intmax_t argument.
200 z Specifies that a following d , i , o , u , x , or X conversion
202 specifier applies to a size_t or the corresponding signed inte‐
203 ger type argument; or that a following n conversion specifier
204 applies to a pointer to a signed integer type corresponding to a
205 size_t argument.
206 t Specifies that a following d , i , o , u , x , or X conversion
208 specifier applies to a ptrdiff_t or the corresponding unsigned
209 type argument; or that a following n conversion specifier
210 applies to a pointer to a ptrdiff_t argument.
211 L Specifies that a following a , A , e , E , f , F , g , or G con‐
213 version specifier applies to a long double argument.
214 If a length modifier appears with any conversion specifier other than
217 as specified above, the behavior is undefined.
218 The conversion specifiers and their meanings are:
220 d, i The int argument shall be converted to a signed decimal in the
222 style "[-]dddd". The precision specifies the minimum number of
223 digits to appear; if the value being converted can be repre‐
224 sented in fewer digits, it shall be expanded with leading zeros.
225 The default precision shall be 1. The result of converting zero
226 with an explicit precision of zero shall be no wide characters.
227 o The unsigned argument shall be converted to unsigned octal for‐
229 mat in the style "dddd" . The precision specifies the minimum
230 number of digits to appear; if the value being converted can be
231 represented in fewer digits, it shall be expanded with leading
232 zeros. The default precision shall be 1. The result of convert‐
233 ing zero with an explicit precision of zero shall be no wide
234 characters.
235 u The unsigned argument shall be converted to unsigned decimal
237 format in the style "dddd" . The precision specifies the minimum
238 number of digits to appear; if the value being converted can be
239 represented in fewer digits, it shall be expanded with leading
240 zeros. The default precision shall be 1. The result of convert‐
241 ing zero with an explicit precision of zero shall be no wide
242 characters.
243 x The unsigned argument shall be converted to unsigned hexadecimal
245 format in the style "dddd" ; the letters "abcdef" are used. The
246 precision specifies the minimum number of digits to appear; if
247 the value being converted can be represented in fewer digits, it
248 shall be expanded with leading zeros. The default precision
249 shall be 1. The result of converting zero with an explicit pre‐
250 cision of zero shall be no wide characters.
251 X Equivalent to the x conversion specifier, except that letters
253 "ABCDEF" are used instead of "abcdef" .
254 f, F The double argument shall be converted to decimal notation in
256 the style "[-]ddd.ddd", where the number of digits after the
257 radix character shall be equal to the precision specification.
258 If the precision is missing, it shall be taken as 6; if the pre‐
259 cision is explicitly zero and no '#' flag is present, no radix
260 character shall appear. If a radix character appears, at least
261 one digit shall appear before it. The value shall be rounded in
262 an implementation-defined manner to the appropriate number of
263 digits.
264 A double argument representing an infinity shall be converted in one of
266 the styles "[-]inf" or "[-]infinity" ; which style is implementation-
267 defined. A double argument representing a NaN shall be converted in one
268 of the styles "[-]nan" or "[-]nan(n-char-sequence)"; which style, and
269 the meaning of any n-char-sequence, is implementation-defined. The F
270 conversion specifier produces "INF" , "INFINITY" , or "NAN" instead of
271 "inf" , "infinity" , or "nan" , respectively.
272 e, E The double argument shall be converted in the style
274 "[-]d.ddde±dd", where there shall be one digit before the radix
275 character (which is non-zero if the argument is non-zero) and
276 the number of digits after it shall be equal to the precision;
277 if the precision is missing, it shall be taken as 6; if the pre‐
278 cision is zero and no '#' flag is present, no radix character
279 shall appear. The value shall be rounded in an implementation-
280 defined manner to the appropriate number of digits. The E con‐
281 version wide character shall produce a number with 'E' instead
282 of 'e' introducing the exponent. The exponent shall always con‐
283 tain at least two digits. If the value is zero, the exponent
284 shall be zero.
285 A double argument representing an infinity or NaN shall be converted in
287 the style of an f or F conversion specifier.
288 g, G The double argument shall be converted in the style f or e (or
290 in the style F or E in the case of a G conversion specifier),
291 with the precision specifying the number of significant digits.
292 If an explicit precision is zero, it shall be taken as 1. The
293 style used depends on the value converted; style e (or E ) shall
294 be used only if the exponent resulting from such a conversion is
295 less than -4 or greater than or equal to the precision. Trailing
296 zeros shall be removed from the fractional portion of the
297 result; a radix character shall appear only if it is followed by
298 a digit.
299 A double argument representing an infinity or NaN shall be converted in
301 the style of an f or F conversion specifier.
302 a, A A double argument representing a floating-point number shall be
304 converted in the style "[-]0xh.hhhhp±d", where there shall be
305 one hexadecimal digit (which is non-zero if the argument is a
306 normalized floating-point number and is otherwise unspecified)
307 before the decimal-point wide character and the number of hexa‐
308 decimal digits after it shall be equal to the precision; if the
309 precision is missing and FLT_RADIX is a power of 2, then the
310 precision shall be sufficient for an exact representation of the
311 value; if the precision is missing and FLT_RADIX is not a power
312 of 2, then the precision shall be sufficient to distinguish val‐
313 ues of type double, except that trailing zeros may be omitted;
314 if the precision is zero and the '#' flag is not specified, no
315 decimal-point wide character shall appear. The letters "abcdef"
316 are used for a conversion and the letters "ABCDEF" for A conver‐
317 sion. The A conversion specifier produces a number with 'X' and
318 'P' instead of 'x' and 'p' . The exponent shall always contain
319 at least one digit, and only as many more digits as necessary to
320 represent the decimal exponent of 2. If the value is zero, the
321 exponent shall be zero.
322 A double argument representing an infinity or NaN shall be converted in
324 the style of an f or F conversion specifier.
325 c If no l (ell) qualifier is present, the int argument shall be
327 converted to a wide character as if by calling the btowc() func‐
328 tion and the resulting wide character shall be written. Other‐
329 wise, the wint_t argument shall be converted to wchar_t, and
330 written.
331 s If no l (ell) qualifier is present, the application shall ensure
333 that the argument is a pointer to a character array containing a
334 character sequence beginning in the initial shift state. Char‐
335 acters from the array shall be converted as if by repeated calls
336 to the mbrtowc() function, with the conversion state described
337 by an mbstate_t object initialized to zero before the first
338 character is converted, and written up to (but not including)
339 the terminating null wide character. If the precision is speci‐
340 fied, no more than that many wide characters shall be written.
341 If the precision is not specified, or is greater than the size
342 of the array, the application shall ensure that the array con‐
343 tains a null wide character.
344 If an l (ell) qualifier is present, the application shall ensure that
346 the argument is a pointer to an array of type wchar_t. Wide characters
347 from the array shall be written up to (but not including) a terminating
348 null wide character. If no precision is specified, or is greater than
349 the size of the array, the application shall ensure that the array con‐
350 tains a null wide character. If a precision is specified, no more than
351 that many wide characters shall be written.
352 p The application shall ensure that the argument is a pointer to
354 void. The value of the pointer shall be converted to a sequence
355 of printable wide characters in an implementation-defined man‐
356 ner.
357 n The application shall ensure that the argument is a pointer to
359 an integer into which is written the number of wide characters
360 written to the output so far by this call to one of the
361 fwprintf() functions. No argument shall be converted, but one
362 shall be consumed. If the conversion specification includes any
363 flags, a field width, or a precision, the behavior is undefined.
364 C Equivalent to lc .
366 S Equivalent to ls .
368 % Output a '%' wide character; no argument shall be converted.
370 The entire conversion specification shall be %% .
371 If a conversion specification does not match one of the above forms,
374 the behavior is undefined.
375 In no case does a nonexistent or small field width cause truncation of
377 a field; if the result of a conversion is wider than the field width,
378 the field shall be expanded to contain the conversion result. Charac‐
379 ters generated by fwprintf() and wprintf() shall be printed as if
380 fputwc() had been called.
381 For a and A conversions, if FLT_RADIX is not a power of 2 and the
383 result is not exactly representable in the given precision, the result
384 should be one of the two adjacent numbers in hexadecimal floating style
385 with the given precision, with the extra stipulation that the error
386 should have a correct sign for the current rounding direction.
387 For e , E , f , F , g , and G conversion specifiers, if the number of
389 significant decimal digits is at most DECIMAL_DIG, then the result
390 should be correctly rounded. If the number of significant decimal dig‐
391 its is more than DECIMAL_DIG but the source value is exactly repre‐
392 sentable with DECIMAL_DIG digits, then the result should be an exact
393 representation with trailing zeros. Otherwise, the source value is
394 bounded by two adjacent decimal strings L < U, both having DECIMAL_DIG
395 significant digits; the value of the resultant decimal string D should
396 satisfy L <= D <= U, with the extra stipulation that the error should
397 have a correct sign for the current rounding direction.
398 The st_ctime and st_mtime fields of the file shall be marked for update
400 between the call to a successful execution of fwprintf() or wprintf()
401 and the next successful completion of a call to fflush() or fclose() on
402 the same stream, or a call to exit() or abort().
403
405 Upon successful completion, these functions shall return the number of
406 wide characters transmitted, excluding the terminating null wide char‐
407 acter in the case of swprintf(), or a negative value if an output error
408 was encountered, and set errno to indicate the error.
409 If n or more wide characters were requested to be written, swprintf()
411 shall return a negative value, and set errno to indicate the error.
412
414 For the conditions under which fwprintf() and wprintf() fail and may
415 fail, refer to fputwc() .
416 In addition, all forms of fwprintf() may fail if:
418 EILSEQ A wide-character code that does not correspond to a valid char‐
420 acter has been detected.
421 EINVAL There are insufficient arguments.
423 In addition, wprintf() and fwprintf() may fail if:
426 ENOMEM Insufficient storage space is available.
428 The following sections are informative.
431
433 To print the language-independent date and time format, the following
434 statement could be used:
435 wprintf(format, weekday, month, day, hour, min);
438 For American usage, format could be a pointer to the wide-character
440 string:
441 L"%s, %s %d, %d:%.2d\n"
444 producing the message:
446 Sunday, July 3, 10:02
449 whereas for German usage, format could be a pointer to the wide-charac‐
451 ter string:
452 L"%1$s, %3$d. %2$s, %4$d:%5$.2d\n"
455 producing the message:
457 Sonntag, 3. Juli, 10:02
460
462 None.
463
465 None.
466
468 None.
469
471 btowc() , fputwc() , fwscanf() , mbrtowc() , setlocale() , the Base
472 Definitions volume of IEEE Std 1003.1-2001, Chapter 7, Locale,
473 <stdio.h>, <wchar.h>
474
476 Portions of this text are reprinted and reproduced in electronic form
477 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
478 -- Portable Operating System Interface (POSIX), The Open Group Base
479 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
480 Electrical and Electronics Engineers, Inc and The Open Group. In the
481 event of any discrepancy between this version and the original IEEE and
482 The Open Group Standard, the original IEEE and The Open Group Standard
483 is the referee document. The original Standard can be obtained online
484 at http://www.opengroup.org/unix/online.html .
485IEEE/The Open Group 2003 FWPRINTF(P)