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@(#)printf.3 8.1 (Berkeley) 6/4/93
FreeBSD: src/lib/libc/stdio/printf.3,v 1.47 2002/09/06 11:23:55 tjr Exp
$FreeBSD$
.Dd July 5, 2003 .Dt WPRINTF 3 .Os .Sh NAME .Nm wprintf , fwprintf , swprintf , .Nm vwprintf , vfwprintf , vswprintf .Nd formatted wide character output conversion .Sh LIBRARY .Lb libc .Sh SYNOPSIS n stdio.h n wchar.h .Ft int .Fn fwprintf "FILE * restrict stream" "const wchar_t * restrict format" ... .Ft int .Fn swprintf "wchar_t * restrict ws" "size_t n" "const wchar_t * restrict format" ... .Ft int .Fn wprintf "const wchar_t * restrict format" ... n stdarg.h .Ft int .Fn vfwprintf "FILE * restrict stream" "const wchar_t * restrict" "va_list ap" .Ft int .Fn vswprintf "wchar_t * restrict ws" "size_t n" "const wchar_t *restrict format" "va_list ap" .Ft int .Fn vwprintf "const wchar_t * restrict format" "va_list ap" .Sh DESCRIPTION The .Fn wprintf family of functions produces output according to a .Fa format as described below. The .Fn wprintf and .Fn vwprintf functions write output to .Dv stdout , the standard output stream; .Fn fwprintf and .Fn vfwprintf write output to the given output .Fa stream ; .Fn swprintf and .Fn vswprintf write to the wide character string .Fa ws .
p These functions write the output under the control of a .Fa format string that specifies how subsequent arguments (or arguments accessed via the variable-length argument facilities of .Xr stdarg 3 ) are converted for output.
p These functions return the number of characters printed (not including the trailing .Ql \e0 used to end output to strings).
p The .Fn swprintf and .Fn vswprintf functions will fail if .Fa n or more wide characters were requested to be written,
p The format string is composed of zero or more directives: ordinary characters (not .Cm % ) , which are copied unchanged to the output stream; and conversion specifications, each of which results in fetching zero or more subsequent arguments. Each conversion specification is introduced by the .Cm % character. The arguments must correspond properly (after type promotion) with the conversion specifier. After the .Cm % , the following appear in sequence: l -bullet t An optional field, consisting of a decimal digit string followed by a .Cm $ , specifying the next argument to access. If this field is not provided, the argument following the last argument accessed will be used. Arguments are numbered starting at .Cm 1 . If unaccessed arguments in the format string are interspersed with ones that are accessed the results will be indeterminate. t Zero or more of the following flags: l -tag -width ".So Sc (space)" t Sq Cm # The value should be converted to an .Dq alternate form . For .Cm c , d , i , n , p , s , and .Cm u conversions, this option has no effect. For .Cm o conversions, the precision of the number is increased to force the first character of the output string to a zero (except if a zero value is printed with an explicit precision of zero). For .Cm x and .Cm X conversions, a non-zero result has the string .Ql 0x (or .Ql 0X for .Cm X conversions) prepended to it. For .Cm a , A , e , E , f , F , g , and .Cm G conversions, the result will always contain a decimal point, even if no digits follow it (normally, a decimal point appears in the results of those conversions only if a digit follows). For .Cm g and .Cm G conversions, trailing zeros are not removed from the result as they would otherwise be. t So Cm 0 Sc (zero) Zero padding. For all conversions except .Cm n , the converted value is padded on the left with zeros rather than blanks. If a precision is given with a numeric conversion .Cm ( d , i , o , u , i , x , and .Cm X ) , the .Cm 0 flag is ignored. t Sq Cm - A negative field width flag; the converted value is to be left adjusted on the field boundary. Except for .Cm n conversions, the converted value is padded on the right with blanks, rather than on the left with blanks or zeros. A .Cm - overrides a .Cm 0 if both are given. t So " " Sc (space) A blank should be left before a positive number produced by a signed conversion .Cm ( a , A , d , e , E , f , F , g , G , or .Cm i ) . t Sq Cm + A sign must always be placed before a number produced by a signed conversion. A .Cm + overrides a space if both are used. t Sq Cm ' Decimal conversions .Cm ( d , u , or .Cm i ) or the integral portion of a floating point conversion .Cm ( f or .Cm F ) should be grouped and separated by thousands using the non-monetary separator returned by .Xr localeconv 3 . .El t An optional decimal digit string specifying a minimum field width. If the converted value has fewer characters than the field width, it will be padded with spaces on the left (or right, if the left-adjustment flag has been given) to fill out the field width. t An optional precision, in the form of a period .Cm . followed by an optional digit string. If the digit string is omitted, the precision is taken as zero. This gives the minimum number of digits to appear for .Cm d , i , o , u , x , and .Cm X conversions, the number of digits to appear after the decimal-point for .Cm a , A , e , E , f , and .Cm F conversions, the maximum number of significant digits for .Cm g and .Cm G conversions, or the maximum number of characters to be printed from a string for .Cm s conversions. t An optional length modifier, that specifies the size of the argument. The following length modifiers are valid for the .Cm d , i , n , o , u , x , or .Cm X conversion: l -column ".Cm q Em (deprecated)" ".Vt signed char" ".Vt unsigned long long" ".Vt long long *" t Sy Modifier Ta Cm d , i Ta Cm o , u , x , X Ta Cm n t Cm hh Ta Vt "signed char" Ta Vt "unsigned char" Ta Vt "signed char *" t Cm h Ta Vt short Ta Vt "unsigned short" Ta Vt "short *" t Cm l No (ell) Ta Vt long Ta Vt "unsigned long" Ta Vt "long *" t Cm ll No (ell ell) Ta Vt "long long" Ta Vt "unsigned long long" Ta Vt "long long *" t Cm j Ta Vt intmax_t Ta Vt uintmax_t Ta Vt "intmax_t *" t Cm t Ta Vt ptrdiff_t Ta (see note) Ta Vt "ptrdiff_t *" t Cm z Ta (see note) Ta Vt size_t Ta (see note) t Cm q Em (deprecated) Ta Vt quad_t Ta Vt u_quad_t Ta Vt "quad_t *" .El
p Note: the .Cm t modifier, when applied to a .Cm o , u , x , or .Cm X conversion, indicates that the argument is of an unsigned type equivalent in size to a .Vt ptrdiff_t . The .Cm z modifier, when applied to a .Cm d or .Cm i conversion, indicates that the argument is of a signed type equivalent in size to a .Vt size_t . Similarly, when applied to an .Cm n conversion, it indicates that the argument is a pointer to a signed type equivalent in size to a .Vt size_t .
p The following length modifier is valid for the .Cm a , A , e , E , f , F , g , or .Cm G conversion: l -column ".Sy Modifier" ".Cm a , A , e , E , f , F , g , G" t Sy Modifier Ta Cm a , A , e , E , f , F , g , G t Cm L Ta Vt "long double" .El
p The following length modifier is valid for the .Cm c or .Cm s conversion: l -column ".Sy Modifier" ".Vt wint_t" ".Vt wchar_t *" t Sy Modifier Ta Cm c Ta Cm s t Cm l No (ell) Ta Vt wint_t Ta Vt "wchar_t *" .El t A character that specifies the type of conversion to be applied. .El
p A field width or precision, or both, may be indicated by an asterisk .Ql * or an asterisk followed by one or more decimal digits and a .Ql $ instead of a digit string. In this case, an .Vt int argument supplies the field width or precision. A negative field width is treated as a left adjustment flag followed by a positive field width; a negative precision is treated as though it were missing. If a single format directive mixes positional
q Li nn$ and non-positional arguments, the results are undefined.
p The conversion specifiers and their meanings are: l -tag -width ".Cm diouxX" t Cm diouxX The .Vt int (or appropriate variant) argument is converted to signed decimal .Cm ( d and .Cm i ) , unsigned octal
q Cm o , unsigned decimal
q Cm u , or unsigned hexadecimal .Cm ( x and .Cm X ) notation. The letters .Dq Li abcdef are used for .Cm x conversions; the letters .Dq Li ABCDEF are used for .Cm X conversions. The precision, if any, gives the minimum number of digits that must appear; if the converted value requires fewer digits, it is padded on the left with zeros. t Cm DOU The .Vt "long int" argument is converted to signed decimal, unsigned octal, or unsigned decimal, as if the format had been .Cm ld , lo , or .Cm lu respectively. These conversion characters are deprecated, and will eventually disappear. t Cm eE The .Vt double argument is rounded and converted in the style .Sm off .Oo - Oc Ar d Li . Ar ddd Li e \(+- Ar dd .Sm on where there is one digit before the decimal-point character and the number of digits after it is equal to the precision; if the precision is missing, it is taken as 6; if the precision is zero, no decimal-point character appears. An .Cm E conversion uses the letter .Ql E (rather than .Ql e ) to introduce the exponent. The exponent always contains at least two digits; if the value is zero, the exponent is 00.
p For .Cm a , A , e , E , f , F , g , and .Cm G conversions, positive and negative infinity are represented as .Li inf and .Li -inf respectively when using the lowercase conversion character, and .Li INF and .Li -INF respectively when using the uppercase conversion character. Similarly, NaN is represented as .Li nan when using the lowercase conversion, and .Li NAN when using the uppercase conversion. t Cm fF The .Vt double argument is rounded and converted to decimal notation in the style .Sm off .Oo - Oc Ar ddd Li . Ar ddd , .Sm on where the number of digits after the decimal-point character is equal to the precision specification. If the precision is missing, it is taken as 6; if the precision is explicitly zero, no decimal-point character appears. If a decimal point appears, at least one digit appears before it. t Cm gG The .Vt double argument is converted in style .Cm f or .Cm e (or .Cm F or .Cm E for .Cm G conversions). The precision specifies the number of significant digits. If the precision is missing, 6 digits are given; if the precision is zero, it is treated as 1. Style .Cm e is used if the exponent from its conversion is less than -4 or greater than or equal to the precision. Trailing zeros are removed from the fractional part of the result; a decimal point appears only if it is followed by at least one digit. t Cm aA The .Vt double argument is converted to hexadecimal notation in the style .Sm off .Oo - Oc Li 0x Ar h Li . Ar hhhp Oo \(+- Oc Ar d , .Sm on where the number of digits after the hexadecimal-point character is equal to the precision specification. If the precision is missing, it is taken as enough to exactly represent the floating-point number; if the precision is explicitly zero, no hexadecimal-point character appears. This is an exact conversion of the mantissa+exponent internal floating point representation; the .Sm off .Oo - Oc Li 0x Ar h Li . Ar hhh .Sm on portion represents exactly the mantissa; only denormalized mantissas have a zero value to the left of the hexadecimal point. The .Cm p is a literal character .Ql p ; the exponent is preceded by a positive or negative sign and is represented in decimal, using only enough characters to represent the exponent. The .Cm A conversion uses the prefix .Dq Li 0X (rather than .Dq Li 0x ) , the letters .Dq Li ABCDEF (rather than .Dq Li abcdef ) to represent the hex digits, and the letter .Ql P (rather than .Ql p ) to separate the mantissa and exponent. t Cm C Treated as .Cm c with the .Cm l (ell) modifier. t Cm c The .Vt int argument is converted to an .Vt "unsigned char" , then to a .Vt wchar_t as if by .Xr btowc 3 , and the resulting character is written.
p If the .Cm l (ell) modifier is used, the .Vt wint_t argument is converted to a .Vt wchar_t and written. t Cm S Treated as .Cm s with the .Cm l (ell) modifier. t Cm s The .Vt "char *" argument is expected to be a pointer to an array of character type (pointer to a string) containing a multibyte sequence. Characters from the array are converted to wide characters and written up to (but not including) a terminating .Dv NUL character; if a precision is specified, no more than the number specified are written. If a precision is given, no null character need be present; if the precision is not specified, or is greater than the size of the array, the array must contain a terminating .Dv NUL character.
p If the .Cm l (ell) modifier is used, the .Vt "wchar_t *" argument is expected to be a pointer to an array of wide characters (pointer to a wide string). Each wide character in the string is written. Wide characters from the array are written up to (but not including) a terminating wide .Dv NUL character; if a precision is specified, no more than the number specified are written (including shift sequences). If a precision is given, no null character need be present; if the precision is not specified, or is greater than the number of characters in the string, the array must contain a terminating wide .Dv NUL character. t Cm p The .Vt "void *" pointer argument is printed in hexadecimal (as if by .Ql %#x or .Ql %#lx ) . t Cm n The number of characters written so far is stored into the integer indicated by the .Vt "int *" (or variant) pointer argument. No argument is converted. t Cm % A .Ql % is written. No argument is converted. The complete conversion specification is .Ql %% . .El
p The decimal point character is defined in the program's locale (category .Dv LC_NUMERIC ) .
p In no case does a non-existent or small field width cause truncation of a numeric field; if the result of a conversion is wider than the field width, the field is expanded to contain the conversion result. .Sh SEE ALSO .Xr btowc 3 , .Xr fputws 3 , .Xr printf 3 , .Xr putwc 3 , .Xr setlocale 3 , .Xr wcsrtombs 3 , .Xr wscanf 3 .Sh STANDARDS Subject to the caveats noted in the .Sx BUGS section of .Xr printf 3 , the .Fn wprintf , .Fn fwprintf , .Fn swprintf , .Fn vwprintf , .Fn vfwprintf and .Fn vswprintf functions conform to .St -isoC-99 . .Sh SECURITY CONSIDERATIONS Refer to .Xr printf 3 .