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 5.9 (Berkeley) 03/14/91 7.\" 8.Vx 9.Vx 10.Dd 11.Dt PRINTF 1 12.AT 1 13.Sh NAME 14.Nm printf 15.Nd formatted output 16.Sh SYNOPSIS 17.Pp 18.Nm printf format 19.Op arguments ... 20.Sh DESCRIPTION 21.Nm Printf 22formats and prints its arguments, after the first, under control 23of the 24.Ar format . 25The 26.Ar format 27is a character string which contains three types of objects: plain characters, 28which are simply copied to standard output, character escape sequences which 29are converted and copied to the standard output, and format specifications, 30each of which causes printing of the next successive 31.Ar argument . 32.Pp 33The 34.Ar arguments 35after the first are treated as strings if the corresponding format is 36either 37.Cm c 38or 39.Cm s ; 40otherwise it is evaluated as a C constant, with the following extensions: 41.Pp 42.Df I 43A leading plus or minus sign is allowed. 44.br 45If the leading character is a single or double quote, or not a digit, 46plus, or minus sign, the value is the ASCII code of the next character. 47.De 48.Pp 49The format string is reused as often as necessary to satisfy the 50.Ar arguments . 51Any extra format specifications are evaluated with zero or the null 52string. 53.Pp 54Character escape sequences are in backslash notation as defined in the 55draft proposed ANSI C Standard X3J11. The characters and their meanings 56are as follows: 57.Tw Ds 58.Tp Cm \ea 59Write a <bell> character. 60.Tp Cm \eb 61Write a <backspace> character. 62.Tp Cm \ef 63Write a <form-feed> character. 64.Tp Cm \en 65Write a <new-line> character. 66.Tp Cm \er 67Write a <carriage return> character. 68.Tp Cm \et 69Write a <tab> character. 70.Tp Cm \ev 71Write a <vertical tab> character. 72.Tp Cm \e\' 73Write a <single quote> character. 74.Tp Cm \e\e 75Write a backslash character. 76.Tp Cx Cm \e 77.Ar num 78.Cx 79Write an 8-bit character whose ASCII value is the 1-, 2-, or 3-digit 80octal number 81.Ar num . 82.Tp 83.Pp 84Each format specification is introduced by the percent character 85(``%''). 86The remainder of the format specification includes, in the 87following order: 88.Pp 89Zero or more of the following flags: 90.Pp 91.Ds I 92.Tw Ds 93.Tp Cm # 94A `#' character 95specifying that the value should be printed in an ``alternate form''. 96For 97.Cm c , 98.Cm d , 99and 100.Cm s , 101formats, this option has no effect. For the 102.Cm o 103formats the precision of the number is increased to force the first 104character of the output string to a zero. For the 105.Cm x 106.Pq Cm X 107format, a non-zero result has the string 108.Li 0x 109.Pq Li 0X 110prepended to it. For 111.Cm e , 112.Cm E , 113.Cm f , 114.Cm g , 115and 116.Cm G , 117formats, the result will always contain a decimal point, even if no 118digits follow the point (normally, a decimal point only appears in the 119results of those formats if a digit follows the decimal point). For 120.Cm g 121and 122.Cm G 123formats, trailing zeros are not removed from the result as they 124would otherwise be; 125.Tp Cm \&\- 126A minus sign `\-' which specifies 127.Em left adjustment 128of the output in the indicated field; 129.Tp Cm \&+ 130A `+' character specifying that there should always be 131a sign placed before the number when using signed formats. 132.Tp Sq \&\ \& 133A space specifying that a blank should be left before a positive number 134for a signed format. A `+' overrides a space if both are used; 135.Tp Cm \&0 136A zero `0' character indicating that zero-padding should be used 137rather than blank-padding. A `\-' overrides a `0' if both are used; 138.Tp 139.De 140.Pp 141.Tw Ds 142.Tp Field Width: 143An optional digit string specifying a 144.Em field width ; 145if the output string has fewer characters than the field width it will 146be blank-padded on the left (or right, if the left-adjustment indicator 147has been given) to make up the field width (note that a leading zero 148is a flag, but an embedded zero is part of a field width); 149.Tp Precision: 150An optional period, 151.Sq Cm \&.\& , 152followed by an optional digit string giving a 153.Em precision 154which specifies the number of digits to appear after the decimal point, 155for 156.Cm e 157and 158.Cm f 159formats, or the maximum number of characters to be printed 160from a string; if the digit string is missing, the precision is treated 161as zero; 162.Tp Format: 163A character which indicates the type of format to use (one of 164.Cm diouxXfwEgGcs ) . 165.Tp 166.Pp 167A field width or precision may be 168.Sq Cm \&* 169instead of a digit string. 170In this case an 171.Ar argument 172supplies the field width or precision. 173.Pp 174The format characters and their meanings are: 175.Tw Fl 176.Tp Cm diouXx 177The 178.Ar argument 179is printed as a signed decimal (d or i), unsigned decimal, unsigned octal, 180or unsigned hexadecimal (X or x), respectively. 181.Tp Cm f 182The 183.Ar argument 184is printed in the style `[\-]ddd.ddd' where the number of d's 185after the decimal point is equal to the precision specification for 186the argument. 187If the precision is missing, 6 digits are given; if the precision 188is explicitly 0, no digits and no decimal point are printed. 189.Tp Cm eE 190The 191.Ar argument 192is printed in the style 193.Cx `[-]d.ddd 194.Cm e 195.Cx \(+-dd\' 196.Cx 197where there 198is one digit before the decimal point and the number after is equal to 199the precision specification for the argument; when the precision is 200missing, 6 digits are produced. 201An upper-case E is used for an `E' format. 202.Tp Cm gG 203The 204.Ar argument 205is printed in style 206.Cm f 207or in style 208.Cm e 209.Pq Cm E 210whichever gives full precision in minimum space. 211.Tp Cm c 212The first character of 213.Ar argument 214is printed. 215.Tp Cm s 216Characters from the string 217.Ar argument 218are printed until the end is reached or until the number of characters 219indicated by the precision specification is reached; however if the 220precision is 0 or missing, all characters in the string are printed. 221.Tp Cm \&% 222Print a `%'; no argument is used. 223.Tp 224.Pp 225In no case does a non-existent or small field width cause truncation of 226a field; padding takes place only if the specified field width exceeds 227the actual width. 228.Sh RETURN VALUE 229.Nm Printf 230exits 0 on success, 1 on failure. 231.Sh SEE ALSO 232.Xr printf 3 233.Sh HISTORY 234.Nm Printf 235as a command, appears in 4.3+Reno BSD. It is modeled 236after the standard library function, 237.Xr printf 3 . 238.Sh BUGS 239Since the number is translated from ASCII to floating-point, and 240then back again, floating-point precision may be lost. 241.Pp 242ANSI hexadecimal character constants were deliberately not provided. 243