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35 .\" @(#)printf.1 8.1 (Berkeley) 6/6/93
46 .Ar format Op Ar arguments ...
50 utility formats and prints its arguments, after the first, under control
55 is a character string which contains three types of objects: plain characters,
56 which are simply copied to standard output, character escape sequences which
57 are converted and copied to the standard output, and format specifications,
58 each of which causes printing of the next successive
63 after the first are treated as strings if the corresponding format is
68 otherwise it is evaluated as a C constant, with the following extensions:
70 .Bl -bullet -offset indent -compact
72 A leading plus or minus sign is allowed.
74 If the leading character is a single or double quote, the value is the
76 code of the next character.
79 The format string is reused as often as necessary to satisfy the
81 Any extra format specifications are evaluated with zero or the null
84 Character escape sequences are in backslash notation as defined in the
87 The characters and their meanings
90 .Bl -tag -width Ds -offset indent -compact
92 Write a <bell> character.
94 Write a <backspace> character.
96 Ignore remaining characters in this string.
98 Write a <form-feed> character.
100 Write a <new-line> character.
102 Write a <carriage return> character.
104 Write a <tab> character.
106 Write a <vertical tab> character.
108 Write a <single quote> character.
110 Write a backslash character.
113 value is the 1-, 2-, or 3-digit
116 Multibyte characters can be constructed using multiple
121 Each format specification is introduced by the percent character
123 The remainder of the format specification includes,
124 in the following order:
126 .It "Zero or more of the following flags:"
130 specifying that the value should be printed in an ``alternate form''.
135 formats, this option has no effect.
138 formats the precision of the number is increased to force the first
139 character of the output string to a zero.
143 format, a non-zero result has the string
148 .Cm a , A , e , E , f , F , g
151 formats, the result will always contain a decimal point, even if no
152 digits follow the point (normally, a decimal point only appears in the
153 results of those formats if a digit follows the decimal point).
158 formats, trailing zeros are not removed from the result as they
161 A minus sign `\-' which specifies
163 of the output in the indicated field;
165 A `+' character specifying that there should always be
166 a sign placed before the number when using signed formats.
168 A space specifying that a blank should be left before a positive number
170 A `+' overrides a space if both are used;
172 A zero `0' character indicating that zero-padding should be used
173 rather than blank-padding.
174 A `\-' overrides a `0' if both are used;
177 An optional digit string specifying a
179 if the output string has fewer characters than the field width it will
180 be blank-padded on the left (or right, if the left-adjustment indicator
181 has been given) to make up the field width (note that a leading zero
182 is a flag, but an embedded zero is part of a field width);
186 followed by an optional digit string giving a
188 which specifies the number of digits to appear after the decimal point,
193 formats, or the maximum number of characters to be printed
194 from a string; if the digit string is missing, the precision is treated
197 A character which indicates the type of format to use (one of
198 .Cm diouxXfFeEgGaAcsb ) .
199 The uppercase formats differ from their lowercase counterparts only in
200 that the output of the former is entirely in uppercase.
201 The floating-point format specifiers
203 may be prefixed by an
205 to request that additional precision be used, if available.
208 A field width or precision may be
210 instead of a digit string.
213 supplies the field width or precision.
215 The format characters and their meanings are:
220 is printed as a signed decimal (d or i), unsigned octal, unsigned decimal,
221 or unsigned hexadecimal (X or x), respectively.
225 is printed in the style `[\-]ddd.ddd' where the number of d's
226 after the decimal point is equal to the precision specification for
228 If the precision is missing, 6 digits are given; if the precision
229 is explicitly 0, no digits and no decimal point are printed.
230 The values \*[If] and \*[Na] are printed as
238 is printed in the style
241 .Sq Op - Ar d.ddd No \(+- Ar dd
244 is one digit before the decimal point and the number after is equal to
245 the precision specification for the argument; when the precision is
246 missing, 6 digits are produced.
247 The values \*[If] and \*[Na] are printed as
261 whichever gives full precision in minimum space.
267 .Sq Op - Ar h.hhh No \(+- Li p Ar d
269 where there is one digit before the hexadecimal point and the number
270 after is equal to the precision specification for the argument;
271 when the precision is missing, enough digits are produced to convey
272 the argument's exact double-precision floating-point representation.
273 The values \*[If] and \*[Na] are printed as
279 The first character of
283 Characters from the string
285 are printed until the end is reached or until the number of characters
286 indicated by the precision specification is reached; however if the
287 precision is 0 or missing, all characters in the string are printed.
291 but interpret character escapes in backslash notation in the string
293 The permitted escape sequences are slightly different in that
299 Print a `%'; no argument is used.
303 character is defined in the program's locale (category
306 In no case does a non-existent or small field width cause truncation of
307 a field; padding takes place only if the specified field width exceeds
314 behavior of converting arguments of numeric formats not beginning
317 code of the first character is not supported.
324 command is expected to be compatible with the
333 after the standard library function,
337 hexadecimal character constants were deliberately not provided.
339 Trying to print a dash ("-") as the first character causes
341 to interpret the dash as a program argument.
346 Since the floating point numbers are translated from
348 to floating-point and
349 then back again, floating-point precision may be lost.
350 (By default, the number is translated to an IEEE-754 double-precision
351 value before being printed.
354 modifier may produce additional precision, depending on the hardware platform.)
356 The escape sequence \e000 is the string terminator.
357 When present in the argument for the
359 format, the argument will be truncated at the \e000 character.
361 Multibyte characters are not recognized in format strings (this is only
364 can appear inside a multibyte character).