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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
69 otherwise it is evaluated as a C constant, with the following extensions:
71 .Bl -bullet -offset indent -compact
73 A leading plus or minus sign is allowed.
75 If the leading character is a single or double quote the value is the ASCII
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 Write an 8-bit character whose
115 value is the 1-, 2-, or 3-digit
120 Each format specification is introduced by the percent character
122 The remainder of the format specification includes,
123 in the following order:
125 .It "Zero or more of the following flags:"
129 specifying that the value should be printed in an ``alternate form''.
135 formats, this option has no effect. For the
137 formats the precision of the number is increased to force the first
138 character of the output string to a zero. For the
141 format, a non-zero result has the string
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). For
157 formats, trailing zeros are not removed from the result as they
160 A minus sign `\-' which specifies
162 of the output in the indicated field;
164 A `+' character specifying that there should always be
165 a sign placed before the number when using signed formats.
167 A space specifying that a blank should be left before a positive number
168 for a signed format. A `+' overrides a space if both are used;
170 A zero `0' character indicating that zero-padding should be used
171 rather than blank-padding. A `\-' overrides a `0' if both are used;
174 An optional digit string specifying a
176 if the output string has fewer characters than the field width it will
177 be blank-padded on the left (or right, if the left-adjustment indicator
178 has been given) to make up the field width (note that a leading zero
179 is a flag, but an embedded zero is part of a field width);
183 followed by an optional digit string giving a
185 which specifies the number of digits to appear after the decimal point,
190 formats, or the maximum number of characters to be printed
191 from a string; if the digit string is missing, the precision is treated
194 A character which indicates the type of format to use (one of
195 .Cm diouxXfwEgGcsb ) .
198 A field width or precision may be
200 instead of a digit string.
203 supplies the field width or precision.
205 The format characters and their meanings are:
210 is printed as a signed decimal (d or i), unsigned octal, unsigned decimal,
211 or unsigned hexadecimal (X or x), respectively.
215 is printed in the style `[\-]ddd.ddd' where the number of d's
216 after the decimal point is equal to the precision specification for
218 If the precision is missing, 6 digits are given; if the precision
219 is explicitly 0, no digits and no decimal point are printed.
223 is printed in the style
226 .Sq Op - Ar d.ddd No \(+- Ar dd
229 is one digit before the decimal point and the number after is equal to
230 the precision specification for the argument; when the precision is
231 missing, 6 digits are produced.
232 An upper-case E is used for an `E' format.
241 whichever gives full precision in minimum space.
243 The first character of
247 Characters from the string
249 are printed until the end is reached or until the number of characters
250 indicated by the precision specification is reached; however if the
251 precision is 0 or missing, all characters in the string are printed.
255 but interpret character escapes in backslash notation in the string
258 Print a `%'; no argument is used.
262 character is defined in the program's locale (category
265 In no case does a non-existent or small field width cause truncation of
266 a field; padding takes place only if the specified field width exceeds
273 behavior of converting arguments of numeric formats not beginning
274 with a digit to the ASCII code of the first characer is not supported.
281 command is expected to be compatible with the
290 after the standard library function,
293 Since the floating point numbers are translated from
295 to floating-point and
296 then back again, floating-point precision may be lost.
299 hexadecimal character constants were deliberately not provided.
301 The escape sequence \e000 is the string terminator. When present in the
305 will be truncated at the \e000 character.