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1.1 root 1: .TH PRINTF 3S "1 April 1981"
2: .SH NAME
3: printf, fprintf, sprintf \- formatted output conversion
4: .SH SYNOPSIS
5: .B #include <stdio.h>
6: .PP
7: .B printf(format
8: .RB [ ,
9: arg ] ...
10: .B )
11: .br
12: .B char *format;
13: .PP
14: .B fprintf(stream, format
15: .RB [ ,
16: arg ] ...
17: .B )
18: .br
19: .SM
20: .B FILE
21: .B *stream;
22: .br
23: .B char *format;
24: .PP
25: .B sprintf(s, format
26: .RB [ ,
27: arg ] ...
28: .B )
29: .br
30: .B char *s, format;
31: .PP
32: .B #include <varargs.h>
33: .br
34: .B _doprnt(format, args, stream)
35: .br
36: .B char *format;
37: .br
38: .B va_list *args;
39: .br
40: .B FILE *stream;
41: .SH DESCRIPTION
42: .I Printf
43: places output on the standard output stream
44: .BR stdout .
45: .I Fprintf
46: places output on the named output
47: .IR stream .
48: .I Sprintf
49: places `output' in the string
50: .IR s ,
51: followed by the character `\\0'.
52: All of these routines work by calling the internal
53: routine
54: .B _doprnt,
55: using the variable-length argument facilities of
56: .IR varargs (3).
57: .PP
58: Each of these functions converts, formats, and prints its arguments after
59: the first under control of the first argument.
60: The first argument is a character string which contains two types of objects:
61: plain characters, which are simply copied to the output stream,
62: and conversion specifications, each of which causes conversion and printing
63: of the next successive
64: .I arg
65: .IR printf .
66: .PP
67: Each conversion specification is introduced by the character
68: .BR % .
69: Following the
70: .BR % ,
71: there may be
72: .TP
73: .B \(bu
74: an optional minus sign `\-' which specifies
75: .I "left adjustment"
76: of the converted value in the indicated field;
77: .TP
78: .B \(bu
79: an optional digit string specifying a
80: .I "field width;"
81: if the converted value has fewer characters than the field width
82: it will be blank-padded on the left (or right,
83: if the left-adjustment indicator has been given) to make up the field width;
84: if the field width begins with a zero,
85: zero-padding will be done instead of blank-padding;
86: .TP
87: .B \(bu
88: an optional period
89: .RB ` . '
90: which serves to separate the field width from the next digit string;
91: .TP
92: .B \(bu
93: an optional digit string specifying a
94: .I precision
95: which specifies the number of digits to appear after the
96: decimal point, for e- and f-conversion, or the maximum number of characters
97: to be printed from a string;
98: .TP
99: .B \(bu
100: the character
101: .B l
102: specifying that a following
103: .BR d ,
104: .BR o ,
105: .BR x ,
106: or
107: .B u
108: corresponds to a long integer
109: .IR arg .
110: .TP
111: .B \(bu
112: a character which indicates the type of
113: conversion to be applied.
114: .PP
115: A field width or precision may be `*' instead of a digit string.
116: In this case an integer
117: .I arg
118: supplies
119: the field width or precision.
120: .PP
121: The conversion characters
122: and their meanings are
123: .TP
124: .B dox
125: The integer
126: .I arg
127: is converted to decimal, octal, or
128: hexadecimal notation respectively.
129: .TP
130: .B f
131: The float or double
132: .I arg
133: is converted to decimal notation
134: in the style `[\fB\-\fR]ddd.ddd'
135: where the number of d's after the decimal point
136: is equal to the precision specification
137: for the argument.
138: If the precision
139: is missing,
140: 6 digits are given;
141: if the precision is explicitly 0, no digits and
142: no decimal point are printed.
143: .TP
144: .B e
145: The float or double
146: .I arg
147: is converted in the style
148: `[\fB\-\fR]d\fB.\fRddd\fBe\fR\(+-dd'
149: where there is one digit before the decimal point and
150: the number after is equal to the
151: precision specification for the argument;
152: when the precision is missing,
153: 6 digits are produced.
154: .TP
155: .B g
156: The float or double
157: .I arg
158: is printed in style
159: .BR d ,
160: in style
161: .BR f ,
162: or in
163: style
164: .BR e ,
165: whichever gives full precision in minimum space.
166: .TP
167: .B c
168: The character
169: .I arg
170: is printed.
171: .TP
172: .B s
173: .I Arg
174: is taken to be a string (character pointer)
175: and characters from the string are printed until
176: a null character or until
177: the number of characters indicated by the precision
178: specification is reached;
179: however if the precision is 0 or missing
180: all characters up to a null are printed.
181: .TP
182: .B u
183: The unsigned integer
184: .I arg
185: is converted to decimal
186: and printed (the result will be in the
187: range 0 through MAXUINT, where MAXUINT equals 4294967295 on a Power 6/32).
188: .TP
189: .B %
190: Print a `%'; no argument is converted.
191: .PP
192: In no case does a non-existent or small field width
193: cause truncation of a field;
194: padding takes place only if the specified field
195: width exceeds the actual width.
196: Characters generated by
197: .I printf
198: are printed by
199: .IR putc (3S).
200: .PP
201: .B Examples
202: .br
203: To print a date and time in the form `Sunday, July 3, 10:02',
204: where
205: .I weekday
206: and
207: .I month
208: are pointers to null-terminated strings:
209: .RS
210: .HP
211: .nh
212: printf("%s, %s %d, %02d:%02d", weekday, month, day, hour, min);
213: .RE
214: .hy
215: .PP
216: To print
217: .if n pi
218: .if t \(*p
219: to 5 decimals:
220: .IP
221: printf("pi = %.5f", 4*atan(1.0));
222: .SH "SEE ALSO"
223: putc(3S),
224: scanf(3S),
225: ecvt(3)
226: .SH BUGS
227: Very wide fields (>128 characters) fail.
228: .br
229: Due to the large size of the floating-point emulating package,
230: the `e', `f' and `g' formats are only available
231: with the `-lf' loader flag; otherwise a `?' is printed.
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