Date:    Fri, 17 Nov 1995 22:30:38 +1100
From:    Steve Clift <Steve.Clift@ml.csiro.au>
To:      python-list@cwi.nl
Subject: Python sscanf() look-alike.


If you miss having a fast and dirty way to scan stuff out of Python
strings, a-la C's sscanf() function, help may be at hand.  I've
uploaded a beta version of a sscanf() look-alike module to
ftp://ftp.python.org/incoming, from where it should soon emerge.

>From the comprehensive documentation at the beginning of the source
file :-):

/*
 * This is a simple C sscanf() analog.  sscanf(input, format) parses
 * the input string according to the format specification and returns
 * a list of the converted values.  The C sscanf() assignment
 * suppression and maximum field width syntax is supported.  An 'l'
 * size modifier causes integer conversions to return a Python
 * long rather than a Python integer; it has no effect for float
 * conversions.
 *
 * Conversion specification are of the form:
 *	%[*][<max_width>]['l']<type_character>.
 *
 * The following format conversions are supported:
 *
 *	%c		Fixed width character string.
 *	%d		Signed integer (leading 0 => octal, 0x => hex).
 *	%f, %g, %e	Python float (C double).
 *	%i		Same as '%d'.
 *	%l		Python long.
 *	%n		Number of characters parsed so far.
 *	%o		Octal integer.
 *	%s		String of non-whitespace characters with leading
 *			whitespace skipped.
 *	%u		Unsigned integer.
 *	%x		Hexadecimal integer.
 *	%[]		Character scan set.
 *
 * Parsing of the format string stops when the input string is exhausted,
 * so format conversion syntax errors will go undetected until there is
 * enough input to reveal them.
 *
 * There are some differences from C sscanf():
 *
 * 1) The %c conversion scans a fixed-width (default 1) character string
 *    rather than a single character, with no special interpretation of
 *    whitespace.  For example, '%5c' converts the next 5 characters or
 *    the remainder of the input string, whichever is the shorter, into
 *    a Python string.  Some C sscanf() implementations also work this
 *    way.
 *
 * 2) If a field width is specified, it sets the maximum number of
 *    characters, starting from the current position, that will be
 *    considered in the conversion.  C sscanf() conversions tend to
 *    skip white space before imposing the field width.  You can
 *    get the C sscanf() behaviour by inserting a space before the
 *    format specification.
 *
 * To install the module in Python, copy the source file into the
 * Modules directory, add the following line to the Modules/Setup
 * file:
 *	sscanf sscanfmodule.c
 * and do a make.
 *
 */

- ----------------------------------------------------------------------------
Steve Clift                                Email: clift@ml.csiro.au
CSIRO Division of Oceanography             Phone: +61-02-32-5243
Hobart, Tasmania, Australia                Fax:   +61-02-32-5000
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