#! /bin/sh
# This is a shell archive, meaning:
# 1. Remove everything above the #! /bin/sh line.
# 2. Save the resulting text in a file.
# 3. Execute the file with /bin/sh (not csh) to create the files:
#	README
#	Makefile
#	date_calc.c
# This archive created: Mon May 14 22:26:17 2001
# By:	Daniel E. Singer (des@cs.duke.edu)
# 	Duke University CS Dept.
export PATH; PATH=/bin:$PATH
echo shar: extracting "'README'" '(3897 characters)'
if test -f 'README'
then
	echo shar: will not over-write existing file "'README'"
else
sed 's/^	X//' << \SHAR_EOF > 'README'
	X
	Xdate_calc: calculate date1 from date0 + number of days
	X	(ie, given a date and an offset in days, compute the second date)
	Xdays_calc: calculate number of days from date0 to date1
	X	(ie, compute the number of days between two dates)
	X
	XThis should be installed with links for both of these names.
	X
	XThis has been tested and used most recently with SunOS 4.1.3 and Solaris 2.5.
	X
	XFiles included with this distribution:
	X
	X.. README	- this file
	X.. Makefile	- the compile makefile
	X.. date_calc.c	- the source
	X
	X===============================================================================
	X% date_calc -h
	X
	Xdate_calc: reports the date of a given number of days from today or from a
	Xspecified date.
	X
	XUsage: date_calc [-ht] [-f fmt] [-s m d y] [+|-]num_days
	X        Options:
	X          -f 'fmt'   - use 'fmt' as the output format, where
	X                       'fmt' is a string of characters in which
	X                       "%n" is replaced by number of days,
	X                       "%y" is replaced by starting year,
	X                       "%m" is replaced by starting month,
	X                       "%d" is replaced by starting day,
	X                       "%Y" is replaced by ending year,
	X                       "%M" is replaced by ending month,
	X                       "%D" is replaced by ending day,
	X                       and "%N" is replaced by newline;
	X          -h         - help, print this message and exit.
	X          -s m d y   - use as the starting date (month, day, year),
	X                       the default is the current date;
	X          -t         - print only the number;
	X        Arguments:
	X          num_days   - a number of days, with optional sign.
	X        Where the year is specified:
	X            if (year >= 0 and year <= 49, 2000 is added;
	X            if (year >= 50 and year <= 99, 1900 is added.
	X        Examples:
	X            % date_calc 500
	X            07/04/1998 and 500 days arrives at 11/16/1999.
	X            % date_calc -s 7 4 50 -f "You will be %n days old on %M/%D/%Y.%N" 20000
	X            You will be 20000 days old on 4/6/2005.
	X
	XSee also: days_calc
	X===============================================================================
	X% days_calc -h
	X
	Xdays_calc: reports the number of days between two dates, starting from today
	Xor a specified date.
	X
	XUsage: days_calc [-ht] [-f fmt] [-s m d y] m d y
	X       days_calc [-ht] [-f fmt] -s m d y
	X        Options:
	X          -f 'fmt'   - use 'fmt' as the output format, where
	X                       'fmt' is a string of characters in which
	X                       "%n" is replaced by number of days,
	X                       "%y" is replaced by starting year,
	X                       "%m" is replaced by starting month,
	X                       "%d" is replaced by starting day,
	X                       "%Y" is replaced by ending year,
	X                       "%M" is replaced by ending month,
	X                       "%D" is replaced by ending day,
	X                       and "%N" is replaced by newline;
	X          -h         - help, print this message and exit.
	X          -s m d y   - use as the starting date (month, day, year),
	X                       the default is the current date;
	X          -t         - print only the number;
	X        Arguments:
	X          m d y      - the ending date (month, day, year); if -s is,
	X                       given, this will default to the current date;
	X            ( 1 <= m <= 12, 1 <= d <= (days in month), y >= 0).
	X        Where the year is specified:
	X            if (year >= 0 and year <= 49, 2000 is added;
	X            if (year >= 50 and year <= 99, 1900 is added.
	X        Examples:
	X            % days_calc 1 1 2000
	X            From 07/04/1998 to 01/01/2000 is 546 days.
	X            % days_calc -s 7 4 50 -f "You are %n days old.%N"
	X            You are 17532 days old.
	X
	XSee also: date_calc
	X===============================================================================
	X
	X-Daniel E. Singer, des@cs.duke.edu, 7/98
SHAR_EOF
if test 3897 -ne "`wc -c < 'README'`"
then
	echo shar: error transmitting "'README'" '(should have been 3897 characters)'
fi
fi # end of overwriting check
echo shar: extracting "'Makefile'" '(786 characters)'
if test -f 'Makefile'
then
	echo shar: will not over-write existing file "'Makefile'"
else
sed 's/^	X//' << \SHAR_EOF > 'Makefile'
	X##
	X## Makefile for 'date_calc'
	X## D.Singer, 9/91
	X##
	X## NOTE:  This code is tested on SunOS 4.1.3 and SunOS 5.x
	X##
	X
	XPROG = date_calc
	XHDRS = 
	XSRCS = ${PROG}.c
	XOBJS = ${PROG}.o
	X#LIBS = -lc
	XFILES = Makefile ${HDRS} ${SRCS}
	X#DEST = /us1/des/bin
	XDEST = /usr/local/bin
	X#CFLAGS = -g
	X
	XSHARE_FILE_NAME = ${PROG}.share
	XSHARE_FILE_NAME_ZIPPED = ${SHARE_FILE_NAME}.gz
	XSHARE_FILES = README Makefile ${PROG}.c 
	X
	X${PROG} : ${OBJS}
	X	cc -o ${PROG} ${OBJS} ${LIBS}
	X
	X${OBJS} : ${HDRS}
	X
	Xinstall :
	X	/usr/bin/cp ${PROG} ${DEST}
	X
	Xclean :
	X	rm -f ${PROG} ${OBJS} a.out core
	X
	Xshare:	${SHARE_FILE_NAME_ZIPPED}
	X
	X${SHARE_FILE_NAME_ZIPPED}: ${SHARE_FILES}
	X	/usr/bin/rm -f ${SHARE_FILE_NAME} ${SHARE_FILE_NAME_ZIPPED}
	X	/usr/local/bin/shar -a ${SHARE_FILES} > ${SHARE_FILE_NAME}
	X	/usr/local/bin/gzip ${SHARE_FILE_NAME}
SHAR_EOF
if test 786 -ne "`wc -c < 'Makefile'`"
then
	echo shar: error transmitting "'Makefile'" '(should have been 786 characters)'
fi
fi # end of overwriting check
echo shar: extracting "'date_calc.c'" '(18961 characters)'
if test -f 'date_calc.c'
then
	echo shar: will not over-write existing file "'date_calc.c'"
else
sed 's/^	X//' << \SHAR_EOF > 'date_calc.c'
	X/*
	X * @(#)  /u/des/src/date_calc/date_calc.c  1.6  01/05/14  22:26:01
	X *
	X * date_calc: calculate date1 from date0 + number of days
	X * days_calc: calculate number of days from date0 to date1
	X * (should install with links for both of these names)
	X *
	X * Copyright (c) 1989-2001 by Daniel E. Singer.  All rights reserved.
	X * Permission is granted to reproduce and distribute this program
	X * with the following conditions:
	X *   1) This copyright notice and the author identification below
	X *      must be left intact in the program and in any copies.
	X *   2) Any modifications to the program must be clearly identified
	X *      in the source file.
	X *
	X * written by Daniel E. Singer
	X * June 1989
	X *
	X * Note: Modified 10/91 for 4.3BSD (original was on PRIMOS)
	X *
	X * Note: until 7/98, this was called "days_old", and was tailored
	X * to calculate number of days from a past date to today.
	X *
	X * Usage:
	X *	date_calc [options] [+|-]num_days
	X *	days_calc [options] m d y
	X *	days_calc [options] -s m d y
	X *
	X * Options:
	X *	-h		: Help -- print help message and exit
	X *	-f format	: Format -- output format string
	X *	-s m d y	: Start -- use as the starting date
	X *	-t		: Terse -- just print the number
	X */
	X
	X#include <stdio.h>
	X#include <ctype.h>
	X#include <time.h>
	X
	X
	X/*
	X * names (links) for this program
	X */
	X#define DATE_CALC_NAME	"date_calc"
	X#define DAYS_CALC_NAME	"days_calc"
	X
	X#define LeapYear(yy)	((yy)%4==0 && ((yy)%100!=0 || (yy)%400==0))
	X#define DaysPerYear(yy)	(365 + LeapYear((yy)))
	X#define DaysPerMonth(yy,mm) ( (mm)==2 ? 28 + LeapYear((yy)) \
	X				: 30 + ((mm)+((mm)>=8))%2 )
	X#define CheckDate(yy,mm,dd) ( (yy)>=0 && (mm)>=1 && (mm)<=12 && \
	X				(dd)>=1 && (dd)<=DaysPerMonth((yy),(mm)) )
	X
	X#define DAYS_MODE	1	/* program called for days calc */
	X#define DATE_MODE	2	/* program called for date calc */
	X
	X#define OPT_CHAR	'-'	/* option indicator */
	X#define PATH_SEP	'/'	/* pathname component separater */
	X#define FMT_CHAR	'%'	/* format indicator */
	X#define DAYS_CHAR	'n'	/* day format */
	X#define NL_CHAR		'N'	/* newline format */
	X#define YEAR0_CHAR	'y'	/* year0 format */
	X#define MONTH0_CHAR	'm'	/* month0 format */
	X#define DAY0_CHAR	'd'	/* day0 format */
	X#define YEAR1_CHAR	'Y'	/* year1 format */
	X#define MONTH1_CHAR	'M'	/* month1 format */
	X#define DAY1_CHAR	'D'	/* day1 format */
	X#define BELL_CHAR	'\007'	/* terminal bell */
	X#define SPACES		" \t"	/* space chars in environment variable */
	X
	X  /* errors */
	X#define E_NONE		0	/* no error */
	X#define E_ARGS		1	/* arg syntax */
	X#define E_UNKNOWN	2	/* unknown arg */
	X#define E_RANGE		3	/* arg out of range */
	X#define E_ENVIRON	4	/* environ var bad format */
	X
	Xstatic char
	X	id[] = "by Daniel E. Singer, des@cs.duke.edu";
	Xchar
	X	*progname,		/* name of this program */
	X	*fmt_str = (char*)0;	/* the output format string */
	Xint
	X	year0, month0, day0,	/* starting date */
	X	year1, month1, day1,	/* ending date */
	X	terse = 0,		/* terse options given */
	X	start_date = 0,		/* start_date option given */
	X	format = 0,		/* format options given */
	X	help = 0,		/* help options given */
	X	mode = 0,		/* which program invocation */
	X	num_days = 0;		/* command line num-days argument
	X				 * or calculated num-days */
	X
	Xchar
	X	*file_name(),
	X	*skip_space(),
	X	*find_space(),
	X	*getenv(),
	X	*malloc();
	Xint
	X	is_integer(),
	X	get_cnum(),
	X	parse_date_str(),
	X	adjust_year(),
	X	get_environment(),
	X	strcmp();
	Xtime_t
	X	time();
	Xvoid
	X	do_args(),
	X	do_format(),
	X	get_todays_date(),
	X	calc_date();
	X
	X
	Xmain(argc,argv)
	Xint	argc;
	Xchar	*argv[];
	X{
	X	progname = file_name(argv[0]);
	X	--argc; ++argv;
	X
	X	if (strcmp(progname,DAYS_CALC_NAME) == 0)
	X		mode = DAYS_MODE;
	X	else if (strcmp(progname,DATE_CALC_NAME) == 0)
	X		mode = DATE_MODE;
	X	else {
	X		fprintf(stderr,"%s%c: who am I?\n",progname,BELL_CHAR);
	X		pr_usage();
	X		exit(1);
	X	}
	X
	X	  /* check for options, and get date args */
	X	do_args(&argc,&argv);
	X
	X	if (mode == DAYS_MODE) {
	X		num_days = date_diff(year0,month0,day0,year1,month1,day1);
	X
	X		if (terse)
	X			fprintf(stdout,"%d",num_days);
	X		else if (format)
	X			do_format(stdout,fmt_str,num_days,year0,month0,day0,year1,month1,day1);
	X		else {
	X			char *tstr = num_days == 1 || num_days == -1 ? "" : "s";
	X
	X			fprintf(stdout,"From %02d/%02d/%04d to %02d/%02d/%04d is %d day%s.\n",
	X				month0,day0,year0,month1,day1,year1,
	X				num_days,tstr);
	X		}
	X	}
	X	else {
	X		calc_date(year0,month0,day0,num_days,&year1,&month1,&day1);
	X
	X		if (terse)
	X			fprintf(stdout,"%02d %02d %04d\n",month1,day1,year1);
	X		else if (format)
	X			do_format(stdout,fmt_str,num_days,year0,month0,day0,year1,month1,day1);
	X		else {
	X			char *tstr = num_days == 1 || num_days == -1 ? "" : "s";
	X
	X			fprintf(stdout,"%02d/%02d/%04d and %d day%s arrives at %02d/%02d/%04d.\n",
	X				month0,day0,year0,
	X				num_days,tstr,
	X				month1,day1,year1);
	X		}
	X	}
	X
	X	exit(0);
	X}
	X
	Xvoid
	Xdo_args(ac,av)
	Xregister int	*ac;
	Xregister char	*(*av[]);
	X{
	X	register char	*argp;
	X	register int	error = E_NONE;
	X	char	*evar;
	X	int	year,
	X		month,
	X		day;
	X
	X	  /* check for options */
	X	for ( ; *ac > 0 && (**av)[0] == OPT_CHAR; --*ac, ++*av) {
	X		argp = &((**av)[0]);
	X
	X		if (mode == DATE_MODE)
	X			  /* check for a negative num-days argument */
	X			if (*(argp+1) >= '0' && *(argp+1) <= '9')
	X				break;
	X
	X		  /* just "-" by itself is an error */
	X		if (*(argp+1) == '\0') {
	X			error = E_ARGS;
	X			break;
	X		}
	X
	X		  /* undocumented feature: "--" means stop processing opts */
	X		if (strcmp(argp,"--") == 0) {
	X			--*ac, ++*av;
	X			break;
	X		}
	X
	X		while (*++argp != '\0') {
	X			switch (*argp) {
	X			    /* help option */
	X			  case 'h':
	X				help = 1;
	X				break;
	X			    /* terse option */
	X			  case 't':
	X				terse = 1;
	X				continue;
	X			    /* format option */
	X			  case 'f':
	X				--*ac, ++*av;
	X				if (*ac < 1) {
	X					error = E_ARGS;
	X					break;
	X				}
	X				fmt_str = (*av)[0];
	X				format = 1;
	X				continue;
	X			    /* start_date (or, date math) option */
	X			  case 's':
	X				--*ac, ++*av;
	X				if (*ac < 1) {
	X					error = E_ARGS;
	X					break;
	X				}
	X				else if (parse_date_str((*av)[0],&month,&day,&year) == 1) {
	X					start_date = 1;
	X					continue;
	X				}
	X				else if (*ac >= 3 && is_integer((*av)[0]) &&
	X					  is_integer((*av)[1]) &&
	X					  is_integer((*av)[2])) {
	X					month = atoi((*av)[0]);
	X					day   = atoi((*av)[1]);
	X					year  = atoi((*av)[2]);
	X					year = adjust_year(year);
	X					*ac -= 2, *av +=2;
	X					start_date = 1;
	X					continue;
	X				}
	X				error = E_ARGS;
	X				break;
	X			  default:
	X				error = E_UNKNOWN;
	X				break;
	X			}
	X			break;
	X		}
	X		if (error != E_NONE)
	X			break;
	X	}
	X
	X	if (help) {
	X		pr_help();
	X		exit(0);
	X	}
	X
	X	  /* check for remaining DOB or NUM-DAYS arguments */
	X	if (error == E_NONE) {
	X		if (mode == DAYS_MODE) {
	X			if (start_date) {
	X				year0  = year;
	X				month0 = month;
	X				day0   = day;
	X			}
	X			else
	X				get_todays_date(&year0,&month0,&day0);
	X			switch (*ac) {
	X			  case 0:
	X				if (!start_date) {
	X					error = E_ARGS;
	X					break;
	X				}
	X				get_todays_date(&year1,&month1,&day1);
	X				break;
	X			  case 1:
	X				  /* get the month day year args from single arg */
	X				if (parse_date_str((*av)[0],&month0,&day0,&year0) == 0)
	X					error = E_ARGS;
	X				break;
	X			  case 3:
	X				  /* get the month day year args */
	X				if ( !is_integer((*av)[0])
	X				     || !is_integer((*av)[1])
	X				     || !is_integer((*av)[2]) )
	X					error = E_ARGS;
	X				else {
	X					  /* get date args */
	X					month1 = atoi((*av)[0]);
	X					day1   = atoi((*av)[1]);
	X					year1  = atoi((*av)[2]);
	X					year1 = adjust_year(year1);
	X				}
	X				break;
	X			  default:
	X				error = E_ARGS;
	X			}
	X		}
	X		else {
	X			if (start_date) {
	X				year0  = year;
	X				month0 = month;
	X				day0   = day;
	X			}
	X			else
	X				get_todays_date(&year0,&month0,&day0);
	X
	X			switch (*ac) {
	X			  case 1:
	X				  /* get the number of days */
	X				if (!get_cnum((*av)[0],&num_days))
	X					error = E_ARGS;
	X				break;
	X			  default:
	X				error = E_ARGS;
	X				break;
	X			}
	X		}
	X	}
	X
	X	if (error == E_NONE) {
	X		  /* check date ranges */
	X		if (mode == DAYS_MODE) {
	X			if ( (start_date && !CheckDate(year0,month0,day0)) ||
	X				  !CheckDate(year1,month1,day1) )
	X				error = E_RANGE;
	X		}
	X		else {
	X			if (start_date && !CheckDate(year0,month0,day0))
	X				error = E_RANGE;
	X		}
	X	}
	X
	X	if (error != E_NONE) {
	X		fprintf(stderr,"%s: ",progname);
	X		switch (error) {
	X		  case E_ARGS:
	X			fprintf(stderr,"syntax error.\n");
	X			break;
	X		  case E_UNKNOWN:
	X			fprintf(stderr,"unknown option '%c'.\n",*argp);
	X			break;
	X		  case E_RANGE:
	X			fprintf(stderr,"an argument is out of range.\n");
	X			break;
	X		  case E_ENVIRON:
	X			fprintf(stderr,"environment variable bad format.\n");
	X			break;
	X		}
	X		putc(BELL_CHAR,stderr);
	X		pr_usage();
	X		exit(error);
	X	}
	X}
	X
	Xpr_usage()
	X{
	X	if (mode == DAYS_MODE) {
	X		fprintf(stderr,"\
	XUsage: %s [-ht] [-f fmt] [-s m d y] m d y\n\
	X       %s [-ht] [-f fmt] -s m d y\n",progname,progname);
	X	}
	X	else {
	X		fprintf(stderr,"\
	XUsage: %s [-ht] [-f fmt] [-s m d y] [+|-]num_days\n",progname);
	X	}
	X}
	X
	Xpr_help()
	X{
	X	if (mode == DAYS_MODE) {
	X		fprintf(stdout,"\
	X\n\
	X%s: reports the number of days between two dates, starting from today\n\
	Xor a specified date.\n\
	X\n\
	XUsage: %s [-ht] [-f fmt] [-s m d y] m d y\n\
	X       %s [-ht] [-f fmt] -s m d y\n\
	X        Options:\n\
	X          -f 'fmt'   - use 'fmt' as the output format, where\n\
	X                       'fmt' is a string of characters in which\n\
	X                       \"%%%c\" is replaced by number of days,\n\
	X                       \"%%%c\" is replaced by starting year,\n\
	X                       \"%%%c\" is replaced by starting month,\n\
	X                       \"%%%c\" is replaced by starting day,\n\
	X                       \"%%%c\" is replaced by ending year,\n\
	X                       \"%%%c\" is replaced by ending month,\n\
	X                       \"%%%c\" is replaced by ending day,\n\
	X                       and \"%%%c\" is replaced by newline;\n\
	X          -h         - help, print this message and exit.\n\
	X          -s m d y   - use as the starting date (month, day, year),\n\
	X                       the default is the current date;\n\
	X          -t         - print only the number;\n\
	X        Arguments:\n\
	X          m d y      - the ending date (month, day, year); if -s is,\n\
	X                       given, this will default to the current date;\n\
	X            ( 1 <= m <= 12, 1 <= d <= (days in month), y >= 0).\n\
	X        Where the year is specified:\n\
	X            if (year >= 0 and year <= 49, 2000 is added;\n\
	X            if (year >= 50 and year <= 99, 1900 is added.\n\
	X        Examples:\n\
	X            %% %s 1 1 2000\n\
	X            From 07/04/1998 to 01/01/2000 is 546 days.\n\
	X            %% %s -s 7 4 50 -f \"You are %%n days old.%%N\"\n\
	X            You are 17532 days old.\n\
	X\n\
	XSee also: %s\n\
	X",
	X		  progname,progname,progname,DAYS_CHAR,
	X		  YEAR0_CHAR,MONTH0_CHAR,DAY0_CHAR,
	X		  YEAR1_CHAR,MONTH1_CHAR,DAY1_CHAR,
	X		  NL_CHAR,progname,progname,DATE_CALC_NAME);
	X	}
	X	else {
	X		fprintf(stdout,"\
	X\n\
	X%s: reports the date of a given number of days from today or from a\n\
	Xspecified date.\n\
	X\n\
	XUsage: %s [-ht] [-f fmt] [-s m d y] [+|-]num_days\n\
	X        Options:\n\
	X          -f 'fmt'   - use 'fmt' as the output format, where\n\
	X                       'fmt' is a string of characters in which\n\
	X                       \"%%%c\" is replaced by number of days,\n\
	X                       \"%%%c\" is replaced by starting year,\n\
	X                       \"%%%c\" is replaced by starting month,\n\
	X                       \"%%%c\" is replaced by starting day,\n\
	X                       \"%%%c\" is replaced by ending year,\n\
	X                       \"%%%c\" is replaced by ending month,\n\
	X                       \"%%%c\" is replaced by ending day,\n\
	X                       and \"%%%c\" is replaced by newline;\n\
	X          -h         - help, print this message and exit.\n\
	X          -s m d y   - use as the starting date (month, day, year),\n\
	X                       the default is the current date;\n\
	X          -t         - print only the number;\n\
	X        Arguments:\n\
	X          num_days   - a number of days, with optional sign.\n\
	X        Where the year is specified:\n\
	X            if (year >= 0 and year <= 49, 2000 is added;\n\
	X            if (year >= 50 and year <= 99, 1900 is added.\n\
	X        Examples:\n\
	X            %% %s 500\n\
	X            07/04/1998 and 500 days arrives at 11/16/1999.\n\
	X            %% %s -s 7 4 50 -f \"You will be %%n days old on %%M/%%D/%%Y.%%N\" 20000\n\
	X            You will be 20000 days old on 4/6/2005.\n\
	X\n\
	XSee also: %s\n\
	X",
	X		  progname,progname,DAYS_CHAR,
	X		  YEAR0_CHAR,MONTH0_CHAR,DAY0_CHAR,
	X		  YEAR1_CHAR,MONTH1_CHAR,DAY1_CHAR,
	X		  NL_CHAR,progname,progname,DAYS_CALC_NAME);
	X	}
	X}
	X
	Xparse_date_str(date_str,month,day,year)
	X/*
	X * parse a numeric date string into month, day, year
	X */
	Xchar
	X	*date_str;	/* format: "mm dd yy" */
	Xint
	X	*month,
	X	*day,
	X	*year;
	X{
	X	char	*m,
	X		*d,
	X		*y,
	X		*junk,
	X		*tstr;
	X
	X	if ((tstr = malloc(strlen(date_str)+1)) == (char*)0) {
	X		putc(BELL_CHAR,stderr);
	X		fprintf(stderr,"%s: problem with malloc().\n",progname);
	X		exit(1);
	X	}
	X	strcpy(tstr,date_str);
	X	m = skip_space(tstr);
	X	d = skip_space(find_space(m));
	X	y = skip_space(find_space(d));
	X	junk = skip_space(find_space(y));
	X
	X	*find_space(m) = '\0';
	X	*find_space(d) = '\0';
	X	*find_space(y) = '\0';
	X
	X	if ( *junk != '\0'
	X	     || !is_integer(m)
	X	     || !is_integer(d)
	X	     || !is_integer(y) ) {
	X		return(0);
	X	}
	X
	X	*month = atoi(m);
	X	*day   = atoi(d);
	X	*year  = atoi(y);
	X	*year = adjust_year(*year);
	X	free(tstr);
	X	return(1);
	X}
	X
	Xint
	Xadjust_year(year)
	X/*
	X * do the Y2K thang
	X */
	Xregister int
	X	year;
	X{
	X	if (year >= 0 && year <= 49)
	X		return(year + 2000);
	X	if (year >= 50 && year <= 99)
	X		return(year + 1900);
	X	return(year);
	X}
	X
	Xvoid
	Xget_todays_date(year,month,day)
	X/*
	X * get the current date
	X */
	Xregister int
	X	*year,
	X	*month,
	X	*day;
	X{
	X	register struct tm
	X		*tmp;
	X	int
	X		the_time;
	X
	X	the_time = time((int*)0);
	X	tmp = localtime(&the_time);
	X
	X	*year  = tmp->tm_year;	/* 0-???: years since 1900 */
	X	*month = tmp->tm_mon;	/* 0-11 */
	X	*day   = tmp->tm_mday;	/* 1-31 */
	X
	X	*year  += 1900;
	X	*month += 1;
	X}
	X
	Xint
	Xdate_diff(year0,month0,day0,year1,month1,day1)
	X/*
	X * compute the difference in days between two dates;
	X * y1, etc, are the later date (otherwise, return negative);
	X * dates are assumed to already be checked for valid range;
	X */
	Xint	year0, month0, day0,	/* earlier date */
	X	year1, month1, day1;	/* later date */
	X{
	X	register int
	X		yy,
	X		mm,
	X		num_days = 0,
	X		reverse,
	X		t;
	X
	X	if (reverse = year0 > year1
	X		|| (year0 == year1
	X			&& (month0 > month1
	X				|| (month0 == month1
	X					&& day0 > day1)))) {
	X		t = year0;  year0  = year1;  year1  = t;
	X		t = month0; month0 = month1; month1 = t;
	X		t = day0;   day0   = day1;   day1   = t;
	X	}
	X
	X	  /* do a gross total of the span of years, then adjust */
	X	for (yy=year0; yy <= year1; ++yy)
	X		num_days += DaysPerYear(yy);
	X
	X	  /* adjust first year */
	X	for (mm=1; mm < month0; ++mm)
	X		num_days -= DaysPerMonth(year0,mm);
	X
	X	  /* adjust last year */
	X	for (mm=month1; mm <= 12; ++mm)
	X		num_days -= DaysPerMonth(year1,mm);
	X
	X	num_days += day1 - day0;
	X
	X	return( reverse ? -num_days : num_days );
	X}
	X
	Xvoid
	Xcalc_date(year0,month0,day0,num_days,year1,month1,day1)
	X/*
	X * compute a new date, based on a starting date and an offset in days;
	X * y0, etc, are the base date; y1, etc, are the calculated date;
	X * num_days is the offset
	X */
	Xint	year0, month0, day0,	/* base date */
	X	num_days,		/* date offset */
	X	*year1, *month1, *day1;	/* calculated date */
	X{
	X	register int
	X		nd = num_days,
	X		yy,
	X		mm,
	X		neg = 0,
	X		t;
	X
	X	if (nd == 0) {
	X		*year1  = year0;
	X		*month1 = month0;
	X		*day1   = day0;
	X		return;
	X	}
	X	if (nd < 0) {
	X		nd = -nd;
	X
	X		/* go to the end of the year, and work backward */
	X		nd += DaysPerMonth(year0,month0) - day0;
	X		while (month0 < 12) {
	X			++month0;
	X			nd += DaysPerMonth(year0,month0);
	X		}
	X
	X		for ( ; ; --year0) {
	X			yy = DaysPerYear(year0);
	X			if (yy > nd)
	X				break;
	X			nd -= yy;
	X		}
	X
	X		for ( ; ; --month0) {
	X			mm = DaysPerMonth(year0,month0);
	X			if (mm > nd)
	X				break;
	X			nd -= mm;
	X		}
	X
	X		day0 = mm - nd;
	X	}
	X	else {
	X		/* go to the beginning of the year, and work forward */
	X		nd += day0 - 1;
	X		while (month0 > 1) {
	X			--month0;
	X			nd += DaysPerMonth(year0,month0);
	X		}
	X
	X		for ( ; ; ++year0) {
	X			yy = DaysPerYear(year0);
	X			if (yy > nd)
	X				break;
	X			nd -= yy;
	X		}
	X
	X		for ( ; ; ++month0) {
	X			mm = DaysPerMonth(year0,month0);
	X			if (mm > nd)
	X				break;
	X			nd -= mm;
	X		}
	X
	X		day0 = nd + 1;
	X	}
	X
	X	*year1 = year0;
	X	*month1 = month0;
	X	*day1 = day0;
	X}
	X
	Xvoid
	Xdo_format(fp,fmt,num)
	X/*
	X * process command line format option, similar to printf();
	X */
	Xregister FILE
	X	*fp;
	Xregister char
	X	*fmt;
	Xint
	X	num;
	X{
	X	register char
	X		*p = fmt;
	X
	X	for ( ; *p != '\0'; ++p) {
	X		if (*p == FMT_CHAR) {
	X			switch (*(p+1)) {
	X			  case FMT_CHAR:
	X				putc(FMT_CHAR,fp);
	X				++p;
	X				continue;
	X			  case DAYS_CHAR:
	X				fprintf(fp,"%d",num);
	X				++p;
	X				continue;
	X			  case NL_CHAR:
	X				putc('\n',fp);
	X				++p;
	X				continue;
	X			  case YEAR0_CHAR:
	X				fprintf(fp,"%d",year0);
	X				++p;
	X				continue;
	X			  case MONTH0_CHAR:
	X				fprintf(fp,"%d",month0);
	X				++p;
	X				continue;
	X			  case DAY0_CHAR:
	X				fprintf(fp,"%d",day0);
	X				++p;
	X				continue;
	X			  case YEAR1_CHAR:
	X				fprintf(fp,"%d",year1);
	X				++p;
	X				continue;
	X			  case MONTH1_CHAR:
	X				fprintf(fp,"%d",month1);
	X				++p;
	X				continue;
	X			  case DAY1_CHAR:
	X				fprintf(fp,"%d",day1);
	X				++p;
	X				continue;
	X			}
	X		}
	X		putc(*p,fp);
	X	}
	X}
	X
	X#if 0
	Xvoid
	Xdo_cformat(fp,fmt,num,year0,month0,day0,year1,month1,day1);
	X/*
	X * process command line format option, similar to printf();
	X */
	Xregister FILE
	X	*fp;
	Xregister char
	X	*fmt;
	Xint
	X	num,
	X	year0,
	X	month0,
	X	day0,
	X	year1,
	X	month1,
	X	day1;
	X{
	X	register char
	X		*p = fmt;
	X
	X	for ( ; *p != '\0'; ++p) {
	X		if (*p == FMT_CHAR) {
	X			switch (*(p+1)) {
	X			  case FMT_CHAR:
	X				putc(FMT_CHAR,fp);
	X				++p;
	X				continue;
	X			  case DAYS_CHAR:
	X				fprintf(fp,"%d",num);
	X				++p;
	X				continue;
	X			  case NL_CHAR:
	X				putc('\n',fp);
	X				++p;
	X				continue;
	X			}
	X		}
	X		putc(*p,fp);
	X	}
	X}
	X#endif
	X
	Xchar*
	Xfile_name(path)
	X/*
	X * return a ptr to the filename part of a pathname;
	X */
	Xregister char
	X	*path;
	X{
	X	register char
	X		*p = path,
	X		*hold = p;
	X
	X	for ( ; *p != '\0'; ++p)
	X		if (*p == PATH_SEP)
	X			hold = p + 1;
	X
	X	return(hold);
	X}
	X
	Xchar*
	Xskip_space(str)
	X/*
	X * return a ptr to the character after space;
	X */
	Xregister char
	X	*str;
	X{
	X	register char
	X		*space = SPACES,
	X		*p;
	X
	X	for ( ; *str != '\0'; ++str) {
	X		for (p=space; *p != '\0' && *p != *str; ++p) ;
	X		if (*p == '\0')
	X			break;
	X	}
	X	return(str);
	X}
	X
	Xchar*
	Xfind_space(str)
	X/*
	X * return a ptr to the first space character, or end of string;
	X */
	Xregister char
	X	*str;
	X{
	X	register char
	X		*space = SPACES,
	X		*p;
	X
	X	for ( ; *str != '\0'; ++str) {
	X		for (p=space; *p != '\0' && *p != *str; ++p) ;
	X		if (*p != '\0')
	X			break;
	X	}
	X	return(str);
	X}
	X
	Xint
	Xget_cnum(str,num)
	Xchar	*str;
	Xint	*num;
	X{
	X	register
	X	char	*p = str;
	X	register
	X	int	sign = 1;
	X
	X	if (*p == '+')
	X		++p;
	X	else if (*p == '-') {
	X		sign = -1;
	X		++p;
	X	}
	X	if (!is_integer(p))
	X		return(0);
	X
	X	*num = sign * atoi(p);
	X	return(1);
	X}
	X
	Xint
	Xis_integer(str)
	X/*
	X * see if this string is exactly an integer;
	X */
	Xregister char	*str;
	X{
	X	char	int_buf[21];
	X
	X	int	len = strlen(str);
	X
	X	if (len > 20)
	X		len = 20;
	X
	X	sprintf(int_buf,"%0*d",len,atoi(str));
	X	/*printf("is_integer: %s -> %s\n", str, int_buf);*/
	X
	X	return( strcmp(int_buf,str) == 0 );
	X}
SHAR_EOF
if test 18961 -ne "`wc -c < 'date_calc.c'`"
then
	echo shar: error transmitting "'date_calc.c'" '(should have been 18961 characters)'
fi
fi # end of overwriting check
#	End of shell archive
exit 0