strparse.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: strparse.3,v 1.1.1.1 2003/02/19 17:29:27 bbraun Exp $
.TH STRPARSE 3X "30 September 1992"
.SH NAME
str_parse, str_endparse, str_component, str_separator, str_nextpos
.SH SYNOPSIS
.LP
.nf
.ft B
#include "str.h"
.LP
.ft B
str_h str_parse( str, separ, flags, errnop )
char *str ;
char *separ ;
int flags ;
int *errnop ;
.LP
.ft B
void str_endparse( handle )
str_h handle ;
.LP
.ft B
char *str_component( handle )
str_h handle ;
.LP
.ft B
int str_setstr( handle, newstr )
str_h handle ;
char *newstr ;
.LP
.ft B
int str_separator( handle, separ )
str_h handle ;
char *separ ;
.LP
.ft B
char *str_nextpos( handle )
str_h handle ;
.LP
extern int str_errno ;
.SH DESCRIPTION
.LP
These functions are useful for parsing strings.  In this context
parsing means breaking the string into substrings. The substrings are
separated by a list of possible separator characters.
.LP
.B str_component()
returns successive substrings of the string.
.B str_parse()
creates and initializes a string parser with the string
that will be processed, \fIstr\fR, the list of possible separator
characters, \fIsepar\fR, and flags that control how the parser
works. The \fIflags\fR argument is formed by ORing one or more of
the following constants:
.TP 20
.SB STR_RETURN_ERROR
If something goes wrong return a value that indicates that an error occured
(e.g. out of memory). The default is for the program to be terminated
with an appropriate error message.
.TP
.SB STR_NULL_START
If \fIstr\fR starts with a separator then a zero-length string will be returned
the first time \fBstr_component()\fR is called.
.TP
.SB STR_NULL_END
If \fIstr\fR ends with a separator then a zero-length string will be returned
by \fBstr_component()\fR when the substrings of \fIstr\fR are exhausted.
.TP
.SB STR_MALLOC
The strings returned by \fBstr_component()\fR will be in malloc'ed memory.
By default the substrings are part of \fIstr\fR.
If this option is not used \fIstr\fR will be modified
by \fBstr_component()\fR.
.LP
Finally, \fBSTR_NOFLAGS\fR may be used to specify no flags.
The \fIerrnop\fR argument points to an integer where the string processing
functions will deposit an error code if an error occurs.
If \fIerrnop\fR
is
.SM NULL
the error codes will be placed in \fIstr_errno\fR.
This is useful only if \fBSTR_RETURN_ERROR\fR is used in \fIflags\fR.
It is possible that \fIstr\fP is 
.SM NULL.
In this case, a subsequent
.B str_setstr()
should be used to specify the string to be processed.
.LP
.B str_component()
returns successive substrings from the string associated with the
parser specified by \fIhandle\fR.
.LP
.B str_endparse()
destroys the parser specified by \fIhandle\fR.
.LP
.B str_setstr()
changes the processed string to \fInewstr\fP.
.LP
.B str_separator()
replaces the list of separator characters with \fIsepar\fR.
Processing continues from the current position.
.LP
.B str_nextpos()
returns a pointer to the rest of the string. The previous character
is a separator character (if \fBSTR_MALLOC\fR is not set, then the
previous character is
.SM NUL
).
.SH "RETURN VALUES"
.LP
.B str_parse()
returns a parser handle or
.SM NULL
if something goes wrong and \fIflags\fR & \fBSTR_RETURN_ERROR\fR is true.
Possible \fIstr_errno\fR values:
.RS
.TP 20
.SB STR_ENULLSEPAR
\fIsepar\fR is
.SM NULL
.TP
.SB STR_ENOMEM
the program ran out of memory
.RE
.LP
.B str_component()
returns a pointer to the next substring or
.SM NULL
if something goes wrong and \fIflags\fR & \fBSTR_RETURN_ERROR\fR is true.
.LP
.B str_setstr()
returns 
.SB STR_OK
on success or
.SB STR_ERR
on failure.
.LP
.B str_separator()
returns 
.SB STR_OK
on success or
.SB STR_ERR
on failure.
.LP
.B str_nextpos()
returns a pointer or
.SM NULL
if the end of string has been reached.
.SH BUGS
.B str_component()
modifies the string unless \fBSTR_MALLOC\fR is
set in the parser.
.LP
There should be only one parser active on a specific string. If there
is more than
one, they all must use the \fBSTR_MALLOC\fR option.