1FPRINTF(P) POSIX Programmer's Manual FPRINTF(P)
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6 fprintf, printf, snprintf, sprintf - print formatted output
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9 #include <stdio.h>
10 int fprintf(FILE *restrict stream, const char *restrict format, ...);
12 int printf(const char *restrict format, ...);
13 int snprintf(char *restrict s, size_t n,
14 const char *restrict format, ...);
15 int sprintf(char *restrict s, const char *restrict format, ...);
16
19 The fprintf() function shall place output on the named output stream.
20 The printf() function shall place output on the standard output stream
21 stdout. The sprintf() function shall place output followed by the null
22 byte, '\0' , in consecutive bytes starting at *s; it is the user's
23 responsibility to ensure that enough space is available.
24 The snprintf() function shall be equivalent to sprintf(), with the
26 addition of the n argument which states the size of the buffer referred
27 to by s. If n is zero, nothing shall be written and s may be a null
28 pointer. Otherwise, output bytes beyond the n-1st shall be discarded
29 instead of being written to the array, and a null byte is written at
30 the end of the bytes actually written into the array.
31 If copying takes place between objects that overlap as a result of a
33 call to sprintf() or snprintf(), the results are undefined.
34 Each of these functions converts, formats, and prints its arguments
36 under control of the format. The format is a character string, begin‐
37 ning and ending in its initial shift state, if any. The format is com‐
38 posed of zero or more directives: ordinary characters, which are simply
39 copied to the output stream, and conversion specifications, each of
40 which shall result in the fetching of zero or more arguments. The
41 results are undefined if there are insufficient arguments for the for‐
42 mat. If the format is exhausted while arguments remain, the excess
43 arguments shall be evaluated but are otherwise ignored.
44 Conversions can be applied to the nth argument after the format in the
46 argument list, rather than to the next unused argument. In this case,
47 the conversion specifier character % (see below) is replaced by the
48 sequence "%n$", where n is a decimal integer in the range
49 [1,{NL_ARGMAX}], giving the position of the argument in the argument
50 list. This feature provides for the definition of format strings that
51 select arguments in an order appropriate to specific languages (see the
52 EXAMPLES section).
53 The format can contain either numbered argument conversion specifica‐
55 tions (that is, "%n$" and "*m$"), or unnumbered argument conversion
56 specifications (that is, % and * ), but not both. The only exception to
57 this is that %% can be mixed with the "%n$" form. The results of mixing
58 numbered and unnumbered argument specifications in a format string are
59 undefined. When numbered argument specifications are used, specifying
60 the Nth argument requires that all the leading arguments, from the
61 first to the (N-1)th, are specified in the format string.
62 In format strings containing the "%n$" form of conversion specifica‐
64 tion, numbered arguments in the argument list can be referenced from
65 the format string as many times as required.
66 In format strings containing the % form of conversion specification,
68 each conversion specification uses the first unused argument in the
69 argument list.
70 All forms of the fprintf() functions allow for the insertion of a lan‐
72 guage-dependent radix character in the output string. The radix charac‐
73 ter is defined in the program's locale (category LC_NUMERIC ). In the
74 POSIX locale, or in a locale where the radix character is not defined,
75 the radix character shall default to a period ( '.' ).
76 Each conversion specification is introduced by the '%' character or by
78 the character sequence "%n$", after which the following appear in
79 sequence:
80 * Zero or more flags (in any order), which modify the meaning of the
82 conversion specification.
83 * An optional minimum field width. If the converted value has fewer
85 bytes than the field width, it shall be padded with spaces by
86 default on the left; it shall be padded on the right if the left-
87 adjustment flag ( '-' ), described below, is given to the field
88 width. The field width takes the form of an asterisk ( '*' ),
89 described below, or a decimal integer.
90 * An optional precision that gives the minimum number of digits to
92 appear for the d , i , o , u , x , and X conversion specifiers; the
93 number of digits to appear after the radix character for the a , A ,
94 e , E , f , and F conversion specifiers; the maximum number of sig‐
95 nificant digits for the g and G conversion specifiers; or the maxi‐
96 mum number of bytes to be printed from a string in the s and S
97 conversion specifiers. The precision takes the form of a period (
98 '.' ) followed either by an asterisk ( '*' ), described below, or an
99 optional decimal digit string, where a null digit string is treated
100 as zero. If a precision appears with any other conversion specifier,
101 the behavior is undefined.
102 * An optional length modifier that specifies the size of the argument.
104 * A conversion specifier character that indicates the type of conver‐
106 sion to be applied.
107 A field width, or precision, or both, may be indicated by an asterisk (
109 '*' ). In this case an argument of type int supplies the field width or
110 precision. Applications shall ensure that arguments specifying field
111 width, or precision, or both appear in that order before the argument,
112 if any, to be converted. A negative field width is taken as a '-' flag
113 followed by a positive field width. A negative precision is taken as if
114 the precision were omitted. In format strings containing the "%n$"
115 form of a conversion specification, a field width or precision may be
116 indicated by the sequence "*m$", where m is a decimal integer in the
117 range [1,{NL_ARGMAX}] giving the position in the argument list (after
118 the format argument) of an integer argument containing the field width
119 or precision, for example:
120 printf("%1$d:%2$.*3$d:%4$.*3$d\n", hour, min, precision, sec);
123 The flag characters and their meanings are:
125 ' The integer portion of the result of a decimal conversion ( %i ,
127 %d , %u , %f , %F , %g , or %G ) shall be formatted with thou‐
128 sands' grouping characters. For other conversions the behavior
129 is undefined. The non-monetary grouping character is used.
130 - The result of the conversion shall be left-justified within the
132 field. The conversion is right-justified if this flag is not
133 specified.
134 + The result of a signed conversion shall always begin with a sign
136 ( '+' or '-' ). The conversion shall begin with a sign only when
137 a negative value is converted if this flag is not specified.
138 <space>
140 If the first character of a signed conversion is not a sign or
141 if a signed conversion results in no characters, a <space> shall
142 be prefixed to the result. This means that if the <space> and
143 '+' flags both appear, the <space> flag shall be ignored.
144 # Specifies that the value is to be converted to an alternative
146 form. For o conversion, it increases the precision (if neces‐
147 sary) to force the first digit of the result to be zero. For x
148 or X conversion specifiers, a non-zero result shall have 0x (or
149 0X) prefixed to it. For a , A , e , E , f , F , g , and G con‐
150 version specifiers, the result shall always contain a radix
151 character, even if no digits follow the radix character. Without
152 this flag, a radix character appears in the result of these con‐
153 versions only if a digit follows it. For g and G conversion
154 specifiers, trailing zeros shall not be removed from the result
155 as they normally are. For other conversion specifiers, the
156 behavior is undefined.
157 0 For d , i , o , u , x , X , a , A , e , E , f , F , g , and G
159 conversion specifiers, leading zeros (following any indication
160 of sign or base) are used to pad to the field width; no space
161 padding is performed. If the '0' and '-' flags both appear, the
162 '0' flag is ignored. For d , i , o , u , x , and X conversion
163 specifiers, if a precision is specified, the '0' flag is
164 ignored. If the '0' and '" flags both appear, the grouping
165 characters are inserted before zero padding. For other conver‐
166 sions, the behavior is undefined.
167 The length modifiers and their meanings are:
170 hh Specifies that a following d , i , o , u , x , or X conversion
172 specifier applies to a signed char or unsigned char argument
173 (the argument will have been promoted according to the integer
174 promotions, but its value shall be converted to signed char or
175 unsigned char before printing); or that a following n conversion
176 specifier applies to a pointer to a signed char argument.
177 h Specifies that a following d , i , o , u , x , or X conversion
179 specifier applies to a short or unsigned short argument (the
180 argument will have been promoted according to the integer promo‐
181 tions, but its value shall be converted to short or unsigned
182 short before printing); or that a following n conversion speci‐
183 fier applies to a pointer to a short argument.
184 l (ell)
186 Specifies that a following d , i , o , u , x , or X conversion
187 specifier applies to a long or unsigned long argument; that a
188 following n conversion specifier applies to a pointer to a long
189 argument; that a following c conversion specifier applies to a
190 wint_t argument; that a following s conversion specifier applies
191 to a pointer to a wchar_t argument; or has no effect on a fol‐
192 lowing a , A , e , E , f , F , g , or G conversion specifier.
193 ll (ell-ell)
195 Specifies that a following d , i , o , u , x , or X conversion
197 specifier applies to a long long or unsigned long long argument;
198 or that a following n conversion specifier applies to a pointer
199 to a long long argument.
200 j Specifies that a following d , i , o , u , x , or X conversion
202 specifier applies to an intmax_t or uintmax_t argument; or that
203 a following n conversion specifier applies to a pointer to an
204 intmax_t argument.
205 z Specifies that a following d , i , o , u , x , or X conversion
207 specifier applies to a size_t or the corresponding signed inte‐
208 ger type argument; or that a following n conversion specifier
209 applies to a pointer to a signed integer type corresponding to a
210 size_t argument.
211 t Specifies that a following d , i , o , u , x , or X conversion
213 specifier applies to a ptrdiff_t or the corresponding unsigned
214 type argument; or that a following n conversion specifier
215 applies to a pointer to a ptrdiff_t argument.
216 L Specifies that a following a , A , e , E , f , F , g , or G con‐
218 version specifier applies to a long double argument.
219 If a length modifier appears with any conversion specifier other than
222 as specified above, the behavior is undefined.
223 The conversion specifiers and their meanings are:
225 d, i The int argument shall be converted to a signed decimal in the
227 style "[-]dddd". The precision specifies the minimum number of
228 digits to appear; if the value being converted can be repre‐
229 sented in fewer digits, it shall be expanded with leading zeros.
230 The default precision is 1. The result of converting zero with
231 an explicit precision of zero shall be no characters.
232 o The unsigned argument shall be converted to unsigned octal for‐
234 mat in the style "dddd". The precision specifies the minimum
235 number of digits to appear; if the value being converted can be
236 represented in fewer digits, it shall be expanded with leading
237 zeros. The default precision is 1. The result of converting
238 zero with an explicit precision of zero shall be no characters.
239 u The unsigned argument shall be converted to unsigned decimal
241 format in the style "dddd". The precision specifies the minimum
242 number of digits to appear; if the value being converted can be
243 represented in fewer digits, it shall be expanded with leading
244 zeros. The default precision is 1. The result of converting
245 zero with an explicit precision of zero shall be no characters.
246 x The unsigned argument shall be converted to unsigned hexadecimal
248 format in the style "dddd"; the letters "abcdef" are used. The
249 precision specifies the minimum number of digits to appear; if
250 the value being converted can be represented in fewer digits, it
251 shall be expanded with leading zeros. The default precision is
252 1. The result of converting zero with an explicit precision of
253 zero shall be no characters.
254 X Equivalent to the x conversion specifier, except that letters
256 "ABCDEF" are used instead of "abcdef" .
257 f, F The double argument shall be converted to decimal notation in
259 the style "[-]ddd.ddd", where the number of digits after the
260 radix character is equal to the precision specification. If the
261 precision is missing, it shall be taken as 6; if the precision
262 is explicitly zero and no '#' flag is present, no radix charac‐
263 ter shall appear. If a radix character appears, at least one
264 digit appears before it. The low-order digit shall be rounded
265 in an implementation-defined manner.
266 A double argument representing an infinity shall be converted in one of
268 the styles "[-]inf" or "[-]infinity" ; which style is implementation-
269 defined. A double argument representing a NaN shall be converted in one
270 of the styles "[-]nan(n-char-sequence)" or "[-]nan" ; which style, and
271 the meaning of any n-char-sequence, is implementation-defined. The F
272 conversion specifier produces "INF" , "INFINITY" , or "NAN" instead of
273 "inf" , "infinity" , or "nan" , respectively.
274 e, E The double argument shall be converted in the style
276 "[-]d.ddde±dd", where there is one digit before the radix char‐
277 acter (which is non-zero if the argument is non-zero) and the
278 number of digits after it is equal to the precision; if the pre‐
279 cision is missing, it shall be taken as 6; if the precision is
280 zero and no '#' flag is present, no radix character shall
281 appear. The low-order digit shall be rounded in an implementa‐
282 tion-defined manner. The E conversion specifier shall produce a
283 number with 'E' instead of 'e' introducing the exponent. The
284 exponent shall always contain at least two digits. If the value
285 is zero, the exponent shall be zero.
286 A double argument representing an infinity or NaN shall be converted in
288 the style of an f or F conversion specifier.
289 g, G The double argument shall be converted in the style f or e (or
291 in the style F or E in the case of a G conversion specifier),
292 with the precision specifying the number of significant digits.
293 If an explicit precision is zero, it shall be taken as 1. The
294 style used depends on the value converted; style e (or E ) shall
295 be used only if the exponent resulting from such a conversion is
296 less than -4 or greater than or equal to the precision. Trailing
297 zeros shall be removed from the fractional portion of the
298 result; a radix character shall appear only if it is followed by
299 a digit or a '#' flag is present.
300 A double argument representing an infinity or NaN shall be converted in
302 the style of an f or F conversion specifier.
303 a, A A double argument representing a floating-point number shall be
305 converted in the style "[-]0xh.hhhhp±d", where there is one
306 hexadecimal digit (which shall be non-zero if the argument is a
307 normalized floating-point number and is otherwise unspecified)
308 before the decimal-point character and the number of hexadecimal
309 digits after it is equal to the precision; if the precision is
310 missing and FLT_RADIX is a power of 2, then the precision shall
311 be sufficient for an exact representation of the value; if the
312 precision is missing and FLT_RADIX is not a power of 2, then the
313 precision shall be sufficient to distinguish values of type dou‐
314 ble, except that trailing zeros may be omitted; if the precision
315 is zero and the '#' flag is not specified, no decimal-point
316 character shall appear. The letters "abcdef" shall be used for a
317 conversion and the letters "ABCDEF" for A conversion. The A con‐
318 version specifier produces a number with 'X' and 'P' instead of
319 'x' and 'p' . The exponent shall always contain at least one
320 digit, and only as many more digits as necessary to represent
321 the decimal exponent of 2. If the value is zero, the exponent
322 shall be zero.
323 A double argument representing an infinity or NaN shall be converted in
325 the style of an f or F conversion specifier.
326 c The int argument shall be converted to an unsigned char, and the
328 resulting byte shall be written.
329 If an l (ell) qualifier is present, the wint_t argument shall be con‐
331 verted as if by an ls conversion specification with no precision and an
332 argument that points to a two-element array of type wchar_t, the first
333 element of which contains the wint_t argument to the ls conversion
334 specification and the second element contains a null wide character.
335 s The argument shall be a pointer to an array of char. Bytes from
337 the array shall be written up to (but not including) any termi‐
338 nating null byte. If the precision is specified, no more than
339 that many bytes shall be written. If the precision is not speci‐
340 fied or is greater than the size of the array, the application
341 shall ensure that the array contains a null byte.
342 If an l (ell) qualifier is present, the argument shall be a pointer to
344 an array of type wchar_t. Wide characters from the array shall be con‐
345 verted to characters (each as if by a call to the wcrtomb() function,
346 with the conversion state described by an mbstate_t object initialized
347 to zero before the first wide character is converted) up to and includ‐
348 ing a terminating null wide character. The resulting characters shall
349 be written up to (but not including) the terminating null character
350 (byte). If no precision is specified, the application shall ensure that
351 the array contains a null wide character. If a precision is specified,
352 no more than that many characters (bytes) shall be written (including
353 shift sequences, if any), and the array shall contain a null wide char‐
354 acter if, to equal the character sequence length given by the preci‐
355 sion, the function would need to access a wide character one past the
356 end of the array. In no case shall a partial character be written.
357 p The argument shall be a pointer to void. The value of the
359 pointer is converted to a sequence of printable characters, in
360 an implementation-defined manner.
361 n The argument shall be a pointer to an integer into which is
363 written the number of bytes written to the output so far by this
364 call to one of the fprintf() functions. No argument is con‐
365 verted.
366 C Equivalent to lc .
368 S Equivalent to ls .
370 % Print a '%' character; no argument is converted. The complete
372 conversion specification shall be %% .
373 If a conversion specification does not match one of the above forms,
376 the behavior is undefined. If any argument is not the correct type for
377 the corresponding conversion specification, the behavior is undefined.
378 In no case shall a nonexistent or small field width cause truncation of
380 a field; if the result of a conversion is wider than the field width,
381 the field shall be expanded to contain the conversion result. Charac‐
382 ters generated by fprintf() and printf() are printed as if fputc() had
383 been called.
384 For the a and A conversion specifiers, if FLT_RADIX is a power of 2,
386 the value shall be correctly rounded to a hexadecimal floating number
387 with the given precision.
388 For a and A conversions, if FLT_RADIX is not a power of 2 and the
390 result is not exactly representable in the given precision, the result
391 should be one of the two adjacent numbers in hexadecimal floating style
392 with the given precision, with the extra stipulation that the error
393 should have a correct sign for the current rounding direction.
394 For the e , E , f , F , g , and G conversion specifiers, if the number
396 of significant decimal digits is at most DECIMAL_DIG, then the result
397 should be correctly rounded. If the number of significant decimal dig‐
398 its is more than DECIMAL_DIG but the source value is exactly repre‐
399 sentable with DECIMAL_DIG digits, then the result should be an exact
400 representation with trailing zeros. Otherwise, the source value is
401 bounded by two adjacent decimal strings L < U, both having DECIMAL_DIG
402 significant digits; the value of the resultant decimal string D should
403 satisfy L <= D <= U, with the extra stipulation that the error should
404 have a correct sign for the current rounding direction.
405 The st_ctime and st_mtime fields of the file shall be marked for update
407 between the call to a successful execution of fprintf() or printf() and
408 the next successful completion of a call to fflush() or fclose() on the
409 same stream or a call to exit() or abort().
410
412 Upon successful completion, the fprintf() and printf() functions shall
413 return the number of bytes transmitted.
414 Upon successful completion, the sprintf() function shall return the
416 number of bytes written to s, excluding the terminating null byte.
417 Upon successful completion, the snprintf() function shall return the
419 number of bytes that would be written to s had n been sufficiently
420 large excluding the terminating null byte.
421 If an output error was encountered, these functions shall return a neg‐
423 ative value.
424 If the value of n is zero on a call to snprintf(), nothing shall be
426 written, the number of bytes that would have been written had n been
427 sufficiently large excluding the terminating null shall be returned,
428 and s may be a null pointer.
429
431 For the conditions under which fprintf() and printf() fail and may
432 fail, refer to fputc() or fputwc() .
433 In addition, all forms of fprintf() may fail if:
435 EILSEQ A wide-character code that does not correspond to a valid char‐
437 acter has been detected.
438 EINVAL There are insufficient arguments.
440 The printf() and fprintf() functions may fail if:
443 ENOMEM Insufficient storage space is available.
445 The snprintf() function shall fail if:
448 EOVERFLOW
450 The value of n is greater than {INT_MAX} or the number of bytes
451 needed to hold the output excluding the terminating null is
452 greater than {INT_MAX}.
453 The following sections are informative.
456
458 Printing Language-Independent Date and Time
459 The following statement can be used to print date and time using a lan‐
460 guage-independent format:
461 printf(format, weekday, month, day, hour, min);
464 For American usage, format could be a pointer to the following string:
466 "%s, %s %d, %d:%.2d\n"
469 This example would produce the following message:
471 Sunday, July 3, 10:02
474 For German usage, format could be a pointer to the following string:
476 "%1$s, %3$d. %2$s, %4$d:%5$.2d\n"
479 This definition of format would produce the following message:
481 Sonntag, 3. Juli, 10:02
484 Printing File Information
486 The following example prints information about the type, permissions,
487 and number of links of a specific file in a directory.
488 The first two calls to printf() use data decoded from a previous stat()
490 call. The user-defined strperm() function shall return a string simi‐
491 lar to the one at the beginning of the output for the following com‐
492 mand:
493 ls -l
496 The next call to printf() outputs the owner's name if it is found using
498 getpwuid(); the getpwuid() function shall return a passwd structure
499 from which the name of the user is extracted. If the user name is not
500 found, the program instead prints out the numeric value of the user ID.
501 The next call prints out the group name if it is found using get‐
503 grgid(); getgrgid() is very similar to getpwuid() except that it shall
504 return group information based on the group number. Once again, if the
505 group is not found, the program prints the numeric value of the group
506 for the entry.
507 The final call to printf() prints the size of the file.
509 #include <stdio.h>
512 #include <sys/types.h>
513 #include <pwd.h>
514 #include <grp.h>
515 char *strperm (mode_t);
518 ...
519 struct stat statbuf;
520 struct passwd *pwd;
521 struct group *grp;
522 ...
523 printf("%10.10s", strperm (statbuf.st_mode));
524 printf("%4d", statbuf.st_nlink);
525 if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
528 printf(" %-8.8s", pwd->pw_name);
529 else
530 printf(" %-8ld", (long) statbuf.st_uid);
531 if ((grp = getgrgid(statbuf.st_gid)) != NULL)
534 printf(" %-8.8s", grp->gr_name);
535 else
536 printf(" %-8ld", (long) statbuf.st_gid);
537 printf("%9jd", (intmax_t) statbuf.st_size);
540 ...
541 Printing a Localized Date String
543 The following example gets a localized date string. The nl_langinfo()
544 function shall return the localized date string, which specifies the
545 order and layout of the date. The strftime() function takes this infor‐
546 mation and, using the tm structure for values, places the date and time
547 information into datestring. The printf() function then outputs dat‐
548 estring and the name of the entry.
549 #include <stdio.h>
552 #include <time.h>
553 #include <langinfo.h>
554 ...
555 struct dirent *dp;
556 struct tm *tm;
557 char datestring[256];
558 ...
559 strftime(datestring, sizeof(datestring), nl_langinfo (D_T_FMT), tm);
560 printf(" %s %s\n", datestring, dp->d_name);
563 ...
564 Printing Error Information
566 The following example uses fprintf() to write error information to
567 standard error.
568 In the first group of calls, the program tries to open the password
570 lock file named LOCKFILE. If the file already exists, this is an error,
571 as indicated by the O_EXCL flag on the open() function. If the call
572 fails, the program assumes that someone else is updating the password
573 file, and the program exits.
574 The next group of calls saves a new password file as the current pass‐
576 word file by creating a link between LOCKFILE and the new password file
577 PASSWDFILE.
578 #include <sys/types.h>
581 #include <sys/stat.h>
582 #include <fcntl.h>
583 #include <stdio.h>
584 #include <stdlib.h>
585 #include <unistd.h>
586 #include <string.h>
587 #include <errno.h>
588 #define LOCKFILE "/etc/ptmp"
591 #define PASSWDFILE "/etc/passwd"
592 ...
593 int pfd;
594 ...
595 if ((pfd = open(LOCKFILE, O_WRONLY | O_CREAT | O_EXCL,
596 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1)
597 {
598 fprintf(stderr, "Cannot open /etc/ptmp. Try again later.\n");
599 exit(1);
600 }
601 ...
602 if (link(LOCKFILE,PASSWDFILE) == -1) {
603 fprintf(stderr, "Link error: %s\n", strerror(errno));
604 exit(1);
605 }
606 ...
607 Printing Usage Information
609 The following example checks to make sure the program has the necessary
610 arguments, and uses fprintf() to print usage information if the
611 expected number of arguments is not present.
612 #include <stdio.h>
615 #include <stdlib.h>
616 ...
617 char *Options = "hdbtl";
618 ...
619 if (argc < 2) {
620 fprintf(stderr, "Usage: %s -%s <file\n", argv[0], Options); exit(1);
621 }
622 ...
623 Formatting a Decimal String
625 The following example prints a key and data pair on stdout. Note use
626 of the '*' (asterisk) in the format string; this ensures the correct
627 number of decimal places for the element based on the number of ele‐
628 ments requested.
629 #include <stdio.h>
632 ...
633 long i;
634 char *keystr;
635 int elementlen, len;
636 ...
637 while (len < elementlen) {
638 ...
639 printf("%s Element%0*ld\n", keystr, elementlen, i);
640 ...
641 }
642 Creating a Filename
644 The following example creates a filename using information from a pre‐
645 vious getpwnam() function that returned the HOME directory of the user.
646 #include <stdio.h>
649 #include <sys/types.h>
650 #include <unistd.h>
651 ...
652 char filename[PATH_MAX+1];
653 struct passwd *pw;
654 ...
655 sprintf(filename, "%s/%d.out", pw->pw_dir, getpid());
656 ...
657 Reporting an Event
659 The following example loops until an event has timed out. The pause()
660 function waits forever unless it receives a signal. The fprintf()
661 statement should never occur due to the possible return values of
662 pause().
663 #include <stdio.h>
666 #include <unistd.h>
667 #include <string.h>
668 #include <errno.h>
669 ...
670 while (!event_complete) {
671 ...
672 if (pause() != -1 || errno != EINTR)
673 fprintf(stderr, "pause: unknown error: %s\n", strerror(errno));
674 }
675 ...
676 Printing Monetary Information
678 The following example uses strfmon() to convert a number and store it
679 as a formatted monetary string named convbuf. If the first number is
680 printed, the program prints the format and the description; otherwise,
681 it just prints the number.
682 #include <monetary.h>
685 #include <stdio.h>
686 ...
687 struct tblfmt {
688 char *format;
689 char *description;
690 };
691 struct tblfmt table[] = {
694 { "%n", "default formatting" },
695 { "%11n", "right align within an 11 character field" },
696 { "%#5n", "aligned columns for values up to 99999" },
697 { "%=*#5n", "specify a fill character" },
698 { "%=0#5n", "fill characters do not use grouping" },
699 { "%^#5n", "disable the grouping separator" },
700 { "%^#5.0n", "round off to whole units" },
701 { "%^#5.4n", "increase the precision" },
702 { "%(#5n", "use an alternative pos/neg style" },
703 { "%!(#5n", "disable the currency symbol" },
704 };
705 ...
706 float input[3];
707 int i, j;
708 char convbuf[100];
709 ...
710 strfmon(convbuf, sizeof(convbuf), table[i].format, input[j]);
711 if (j == 0) {
714 printf("%s %s %s\n", table[i].format,
715 convbuf, table[i].description);
716 }
717 else {
718 printf(" %s\n", convbuf);
719 }
720 ...
721 Printing Wide Characters
723 The following example prints a series of wide characters. Suppose that
724 "L`@`" expands to three bytes:
725 wchar_t wz [3] = L"@@"; // Zero-terminated
728 wchar_t wn [3] = L"@@@"; // Unterminated
729 fprintf (stdout,"%ls", wz); // Outputs 6 bytes
732 fprintf (stdout,"%ls", wn); // Undefined because wn has no terminator
733 fprintf (stdout,"%4ls", wz); // Outputs 3 bytes
734 fprintf (stdout,"%4ls", wn); // Outputs 3 bytes; no terminator needed
735 fprintf (stdout,"%9ls", wz); // Outputs 6 bytes
736 fprintf (stdout,"%9ls", wn); // Outputs 9 bytes; no terminator needed
737 fprintf (stdout,"%10ls", wz); // Outputs 6 bytes
738 fprintf (stdout,"%10ls", wn); // Undefined because wn has no terminator
739 In the last line of the example, after processing three characters,
741 nine bytes have been output. The fourth character must then be examined
742 to determine whether it converts to one byte or more. If it converts
743 to more than one byte, the output is only nine bytes. Since there is no
744 fourth character in the array, the behavior is undefined.
745
747 If the application calling fprintf() has any objects of type wint_t or
748 wchar_t, it must also include the <wchar.h> header to have these
749 objects defined.
750
752 None.
753
755 None.
756
758 fputc() , fscanf() , setlocale() , strfmon() , wcrtomb() , the Base
759 Definitions volume of IEEE Std 1003.1-2001, Chapter 7, Locale,
760 <stdio.h>, <wchar.h>
761
763 Portions of this text are reprinted and reproduced in electronic form
764 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
765 -- Portable Operating System Interface (POSIX), The Open Group Base
766 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
767 Electrical and Electronics Engineers, Inc and The Open Group. In the
768 event of any discrepancy between this version and the original IEEE and
769 The Open Group Standard, the original IEEE and The Open Group Standard
770 is the referee document. The original Standard can be obtained online
771 at http://www.opengroup.org/unix/online.html .
772IEEE/The Open Group 2003 FPRINTF(P)