1.\" Copyright (c) 1989, 1990 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)printf.1 5.8 (Berkeley) 07/24/90 7.\" 8.Dd 9.Dt PRINTF 1 10.AT 1 11.Sh NAME 12.Nm printf 13.Nd formatted output 14.Sh SYNOPSIS 15.Pp 16.Nm printf format 17.Op arguments ... 18.Sh DESCRIPTION 19.Nm Printf 20formats and prints its arguments, after the first, under control 21of the 22.Ar format . 23The 24.Ar format 25is a character string which contains three types of objects: plain characters, 26which are simply copied to standard output, character escape sequences which 27are converted and copied to the standard output, and format specifications, 28each of which causes printing of the next successive 29.Ar argument . 30.Pp 31The 32.Ar arguments 33after the first are treated as strings if the corresponding format is 34either 35.Cm c 36or 37.Cm s ; 38otherwise it is evaluated as a C constant, with the following extensions: 39.Pp 40.Df I 41A leading plus or minus sign is allowed. 42.br 43If the leading character is a single or double quote, or not a digit, 44plus, or minus sign, the value is the ASCII code of the next character. 45.De 46.Pp 47The format string is reused as often as necessary to satisfy the 48.Ar arguments . 49Any extra format specifications are evaluated with zero or the null 50string. 51.Pp 52Character escape sequences are in backslash notation as defined in the 53draft proposed ANSI C Standard X3J11. The characters and their meanings 54are as follows: 55.Tw Ds 56.Tp Cm \ea 57Write a <bell> character. 58.Tp Cm \eb 59Write a <backspace> character. 60.Tp Cm \ef 61Write a <form-feed> character. 62.Tp Cm \en 63Write a <new-line> character. 64.Tp Cm \er 65Write a <carriage return> character. 66.Tp Cm \et 67Write a <tab> character. 68.Tp Cm \ev 69Write a <vertical tab> character. 70.Tp Cm \e\' 71Write a <single quote> character. 72.Tp Cm \e\e 73Write a backslash character. 74.Tp Cx Cm \e 75.Ar num 76.Cx 77Write an 8-bit character whose ASCII value is the 1-, 2-, or 3-digit 78octal number 79.Ar num . 80.Tp 81.Pp 82Each format specification is introduced by the percent character 83(``%''). 84The remainder of the format specification includes, in the 85following order: 86.Pp 87Zero or more of the following flags: 88.Pp 89.Ds I 90.Tw Ds 91.Tp Cm # 92A `#' character 93specifying that the value should be printed in an ``alternate form''. 94For 95.Cm c , 96.Cm d , 97and 98.Cm s , 99formats, this option has no effect. For the 100.Cm o 101formats the precision of the number is increased to force the first 102character of the output string to a zero. For the 103.Cm x 104.Pq Cm X 105format, a non-zero result has the string 106.Li 0x 107.Pq Li 0X 108prepended to it. For 109.Cm e , 110.Cm E , 111.Cm f , 112.Cm g , 113and 114.Cm G , 115formats, the result will always contain a decimal point, even if no 116digits follow the point (normally, a decimal point only appears in the 117results of those formats if a digit follows the decimal point). For 118.Cm g 119and 120.Cm G 121formats, trailing zeros are not removed from the result as they 122would otherwise be; 123.Tp Cm \&\- 124A minus sign `\-' which specifies 125.Em left adjustment 126of the output in the indicated field; 127.Tp Cm \&+ 128A `+' character specifying that there should always be 129a sign placed before the number when using signed formats. 130.Tp Sq \&\ \& 131A space specifying that a blank should be left before a positive number 132for a signed format. A `+' overrides a space if both are used; 133.Tp Cm \&0 134A zero `0' character indicating that zero-padding should be used 135rather than blank-padding. A `\-' overrides a `0' if both are used; 136.Tp 137.De 138.Pp 139.Tw Ds 140.Tp Field Width: 141An optional digit string specifying a 142.Em field width ; 143if the output string has fewer characters than the field width it will 144be blank-padded on the left (or right, if the left-adjustment indicator 145has been given) to make up the field width (note that a leading zero 146is a flag, but an embedded zero is part of a field width); 147.Tp Precision: 148An optional period, 149.Sq Cm \&.\& , 150followed by an optional digit string giving a 151.Em precision 152which specifies the number of digits to appear after the decimal point, 153for 154.Cm e 155and 156.Cm f 157formats, or the maximum number of characters to be printed 158from a string; if the digit string is missing, the precision is treated 159as zero; 160.Tp Format: 161A character which indicates the type of format to use (one of 162.Cm diouxXfwEgGcs ) . 163.Tp 164.Pp 165A field width or precision may be 166.Sq Cm \&* 167instead of a digit string. 168In this case an 169.Ar argument 170supplies the field width or precision. 171.Pp 172The format characters and their meanings are: 173.Tw Fl 174.Tp Cm diouXx 175The 176.Ar argument 177is printed as a signed decimal (d or i), unsigned decimal, unsigned octal, 178or unsigned hexadecimal (X or x), respectively. 179.Tp Cm f 180The 181.Ar argument 182is printed in the style `[\-]ddd.ddd' where the number of d's 183after the decimal point is equal to the precision specification for 184the argument. 185If the precision is missing, 6 digits are given; if the precision 186is explicitly 0, no digits and no decimal point are printed. 187.Tp Cm eE 188The 189.Ar argument 190is printed in the style 191.Cx `[-]d.ddd 192.Cm e 193.Cx \(+-dd\' 194.Cx 195where there 196is one digit before the decimal point and the number after is equal to 197the precision specification for the argument; when the precision is 198missing, 6 digits are produced. 199An upper-case E is used for an `E' format. 200.Tp Cm gG 201The 202.Ar argument 203is printed in style 204.Cm f 205or in style 206.Cm e 207.Pq Cm E 208whichever gives full precision in minimum space. 209.Tp Cm c 210The first character of 211.Ar argument 212is printed. 213.Tp Cm s 214Characters from the string 215.Ar argument 216are printed until the end is reached or until the number of characters 217indicated by the precision specification is reached; however if the 218precision is 0 or missing, all characters in the string are printed. 219.Tp Cm \&% 220Print a `%'; no argument is used. 221.Tp 222.Pp 223In no case does a non-existent or small field width cause truncation of 224a field; padding takes place only if the specified field width exceeds 225the actual width. 226.Sh RETURN VALUE 227.Nm Printf 228exits 0 on success, 1 on failure. 229.Sh SEE ALSO 230.Xr printf 3 231.Sh HISTORY 232.Nm Printf 233as a command, appears in 4.3+Reno BSD. It is modeled 234after the standard library function, 235.Xr printf 3 . 236.Sh BUGS 237Since the number is translated from ASCII to floating-point, and 238then back again, floating-point precision may be lost. 239.Pp 240ANSI hexadecimal character constants were deliberately not provided. 241