sprint.3

牛顿插值方法求解多项式的系数

.\"(c) Copyright 1992, 1993 by Panagiotis Tsirigotis
.\"All rights reserved.  The file named COPYRIGHT specifies the terms 
.\"and conditions for redistribution.
.\"
.\" $Id: Sprint.3,v 1.1.1.1 2003/02/19 17:29:27 bbraun Exp $
.TH Sprint 3X "29 May 1992"
.SH NAME
Sprint -- formatted stream output
.SH SYNOPSIS
.LP
.nf
.ft B
int Sprint( fd, format [ , ... ] )
int fd ;
char *format ;
.SH DESCRIPTION
\fBSprint()\fR provides formatted output conversion. The formatting is
controlled by the \fIformat\fR argument. All characters in
\fIformat\fR that do not specify a conversion are printed. A conversion
is specified by a '%' followed by a string that ends with a
conversion type character. The string may contain flags, a field width,
a precision, and a modifier.
.LP
Possible flags (more that one can be specified and they can be in any order)
include:
.TP 10
.B \'-'
specifies left adjustment of the converted argument. The default
is right adjustment. This flag is meaningful only if a field width
is specified.
.TP
.B \'+'
specifies that a number will always have a sign as a prefix (this
forces a '+' sign to appear if the number is positive).
.TP
.B \' '
prefixes a \fIspace\fR to the number if the number has not a sign
(therefore the '+' flag overrides this flag).
.TP
.B \'#'
The meaning of '#' depends on the conversion type character: for \fBo\fR 
conversions the first digit will be 0; for \fBx\fR or \fBX\fR conversions
\fB0x\fR or \fB0X\fR respectively will be prefixed to the number (if it
is not zero); for \fBe\fR, \fBE\fR, \fBf\fR, \fBg\fR, and \fBG\fR conversions
the number will always have a decimal point.
.TP
.B \'0'
specifies padding with zeros instead of spaces.
.LP
The field width is specified by a number. This number indicates the
\fIminimum\fR width for the field. A '*' may be used instead of the number.
In that case the width is the value of the next argument which should
be an \fBint\fR. 
A negative width value specifies left adjustment with a width equal
to the absolute width value.
.LP
A precision is specified by a '.' followed by a number. The meaning of
the precision depends on the type conversion character. For a string
conversion, precision determines how many characters are printed from
the string. For integer conversions, precision determines the 
number of digits used to print the number (zero padding is done if
the precision exceeds the length of the number). For floating point
conversions, precision determines the number of digits after the
decimal point (\fBe\fR, \fBE\fR, \fBf\fR) or the number of
significant digits (\fBg\fR, \fBG\fR).
A '*' may be used instead of a number to specify the precision. In that
case the precision is the value of the next argument which should
be an \fBint\fR.
The behavior of \fBSprint()\fR is undefined if the precision is negative.
.LP
The length modifier is \fBl\fR and indicates that the argument is
a \fBlong\fR integer.
.LP
The type conversion characters are:
\fBd, i, o, x, X, u, c, s, f, e, E, g, G, p, n, %\fR.
For floating point conversions the argument should be of type \fIdouble\fR.
.TP 10
.B d,i
specify signed decimal conversion.
.TP
.B u
specifies unsigned decimal conversion.
.TP
.B o
specifies octal conversion.
.TP
.B x,X
specify hexadecimal conversion. For 
.B x
the hex digits used are 0123456789abcdef. For
.B X
the hex digits used are 0123456789ABCDEF.
There is no leading
.B 0x
or
.B 0X
(use the '#' flag for that).
.TP
.B c
specifies character conversion; the argument should be of type
\fIchar\fR.
.TP
.B s
specifies string conversion; the argument should be of type
\fIchar *\fR.
.TP
.B f
specifies conversion to the form [-]ddd.dddd. The number
of digits after the decimal point depends on precision; the default is 6.
If the precision is 0, the decimal point is not printed (this can
be overriden with the '#' flag).
.B e,E
specify conversion to the form [-]ddd.dddd[eE][+-]ddd.
The number of digits after the decimal point depends on precision;
the default is 6. If the precision is 0, the decimal point is not printed
(this can be overriden with the '#' flag).
The exponent is at least 2 digit wide.
.TP
.B g,G
specify a conversion using the
.B e,E
format respectively if the
exponent is less than -4 or greater than or equal to the precision;
otherwise the 
.B f
format is used.
.TP
.B p
is used to print pointers (type \fIvoid *\fR,
or \fIchar *\fR if the compiler does not support the former).
.TP
.B n
expects a \fIint *\fR argument and puts in that integer 
the number of characters already printed by this call.
.TP
.B %
is used to print a \fI%\fR.
.LP
If an unknown conversion character is specified, the percent sign
followed by that character will be printed.
.SH RETURN VALUE
.LP
If no error occured, \fBSprint()\fR returns the number of characters
printed. In case of error, it returns \fBSIO_ERR\fR.
.SH BUGS
.LP
This is a list of differences between \fBSprint()\fR and the ANSI C Standard
\fBprintf()\fR:
.LP
\fBSprint()\fR does not support non-removal of trailing zeroes for
\fBg\fR and \fBG\fR conversions when the '#' flag is used.
.LP
\fBSprint()\fR does not support the h and L modifiers.
.LP
The current implementation assumes that \fIsizeof(int)==sizeof(long)\fR.
.LP
\fBSprint()\fR supports "%p" only if \fIsizeof(pointer)<=sizeof(int)\fR.