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"DAYS-CALCULATOR"tm copyright 1991, BRIAN ALLEN KUEHN. This is a shareware product. If you find it to be of use to you, then you must pay for it. The cost of this software product is $12.00 postpaid. Please order from and make checks payable to: Brian Allen Kuehn 1524 Upper Spring Bay Road East Peoria, Illinois 61611 As an inducement (read coercion) to get you to pay for this program if it is useful to you, I have built in a time delay between the initial shareware announcement screen and the MAIN MENU screen. The delay increases each time you invoke the program until the delay becomes unbearable. At that point, having found the program to be so valuable, you break down and send me a check for $12.00. I then mail you a floppy with a "clean" copy of the program that does away both with the shareware announcement screen and all delays. When you invoke the "clean" copy of the program, you are instantly greeted with the MAIN MENU. THIS PROGRAM WAS CREATED BECAUSE... I created this program partially for my own use. I am an attorney. I concentrate my practice in the areas of worker's compensation and personal injury. As a part of my everyday work, I find it necessary to calculate periods of disability. For instance, one of my clients might be off work between 3/13/1987 and 11/26/1991. You could get out paper calendars and start writing down day totals from each month to add up. You could start reciting "30 days hath September, April, June and November..." to figure the number of days between these two dates. Neither way is particularly easy or enjoyable. Casio and Radio Shack used to make calculators which did date calculations. To the best of my knowledge there are no longer any hand-held calculators available which do date calculations. I have looked because for years I made use of these calculators. The way that disability periods are utilized in the legal profession makes it handy to express the result in terms of weeks and parts thereof. That is why I chose to output the two days-between-dates calculations as both total days and also as weeks and parts thereof. If anyone feels it would be beneficial to express the results in any further fashion, please let me know and I will consider making the necessary changes to the program. In addition to days between dates, I am constantly diarying my calendar for future deadlines. I may go into court on a given day and be given 90 days in which to file a brief on some issue. That is why I put the two routines in that add or subtract a number of days from today's date or from some other specified date to give you a resulting date. The last routine was added because people like to play with dates. You can check and see what day of the week you were born on or what day of the week some significant event occurred on. This routine also calculates the sequential day in the calendar year for the date which you have entered. USING THE PROGRAM When you start the program, by typing either "days" or "day m" at the DOS prompt (followed by a press of the return key), you will be greeted by the following screen: "DAYS-CALCULATOR"tm copyright 1991, BRIAN ALLEN KUEHN. MAIN MENU. 1. Number of days between two dates. 2. Number of days between today and any other date. 3. Today's date plus/minus 'X' number of days. 4. Any date plus/minus 'X' number of days. 5. Day of the week & of the year for a given date. 6. Exit. YOUR CHOICE PLEASE! _ Enter the number of your choice, between 1 and 6, and press 'RETURN'. 1. Main Menu choice number 1 prompts you to enter two dates. After you have done this, the number of days between those two dates will be shown as both days and also as weeks and parts thereof. Please note that in this as in all of the date entry routines, you must enter ALL of the digits for the year portion of the date. A representative screen from option number 1 is as follows: "DAYS-CALCULATOR"tm copyright 1991, BRIAN ALLEN KUEHN. Enter one or two digit month: 5 Enter one or two digit day: 11 Enter entire year (ALL DIGITS PLEASE!): 1987 First date = Monday, May 11, 1987. Enter one or two digit month: 12 Enter one or two digit day: 18 Enter entire year (ALL DIGITS PLEASE!): 1991 Second date = Wednesday, December 18, 1991. There are 1682 days between dates entered. There are 240 & 2/7ths weeks between dates entered. page 2 1. Run the same program again. 2. Return to MAIN MENU. 3. Send INPUT & RESULTS to printer. 4. Copy INPUT & RESULTS to file. YOUR CHOICE PLEASE! _ 2. Main Menu choice number 2 is similar to choice number one, except that it reads the date from the clock in your computer and uses the date it finds there as the first of the two dates. If your computer doesn't have a correctly functioning clock, this routine will start you with a date that does not represent the current date. Please check the date given as "Today's date" when you use this menu option. You will then be prompted to enter a second date. After you have done this, the number of days between those two dates will be shown as both days and also as weeks and parts thereof. Please note that in this as in all of the date entry routines, you must enter ALL of the digits for the year portion of the date. 3. Main Menu choice number 3 checks the onboard clock on your computer for the current date, displays that date, and then permits you to specify a number of days to add to or subtract from the current date. It will then tell you what the resulting date is, after addition or subtraction of the specified number of days. If your computer doesn't have a correctly functioning clock, this routine will start you with a date that does not represent the current date. Please check the date given as "Today's date" when you use this menu option. A representative screen from option number 3 is as follows: "DAYS-CALCULATOR"tm copyright 1991, BRIAN ALLEN KUEHN. CAUTION: The date given below is the date your computer claims is today's date. If the date is not correct, then reset the date using the DOS 'date' command or use the manual version (option 4) of this program on the Main Menu. Today's date = Friday, December 20, 1991. Please enter the number of days which you would like to add to or subtract from today's date. Please precede a number to be subtracted with a 'minus' (-) sign. You do not need to enter a plus sign for a number to be added. ENTER NUMBER OF DAYS TO ADD/SUBTRACT: 120 Resulting date = Saturday, April 18, 1992. 1. Run the same program again. 2. Return to MAIN MENU. 3. Send INPUT & RESULTS to printer. 4. Copy INPUT & RESULTS to file. YOUR CHOICE PLEASE! _ page 3 4. Main Menu choice number 4 is similar to choice 3 except the beginning date is manually entered. After you enter the first date, you are prompted to enter a number of days to either add to or subtract from the beginning date. It will then tell you what the resulting date is, after addition or subtraction of the specified number of days. Please note that in this as in all of the date entry routines, you must enter ALL of the digits for the year portion of the date. 5. Main Menu choice number 5 prompts you to enter a date. It then tells you what day of the week that date falls on. It also tells you what the day number for the calendar year is. For instance, 12/31/1991 is day number 365 (the 365th day) in calendar year 1991. Please note that in this as in all of the date entry routines, you must enter ALL of the digits for the year portion of the date. Each of the first 5 menu choices, when invoked and completed, present you with the following submenu: 1. Run the same program again. 2. Return to MAIN MENU. 3. Send INPUT & RESULTS to printer. 4. Copy INPUT & RESULTS to file. YOUR CHOICE PLEASE! _ Option 1 allows you to run the same routine you just ran over again, inputting different dates or a different number of days to add or subtract. Option 2 sends you back to the main menu where you can chose a different routine to run or you can EXIT by choosing option 6 from the MAIN MENU. Option 3 copies the important information (the things shown in yellow in the color version of the program) to the printer. If the printer is not turned on, the program will not crash, but neither will it print anything. When using this option, you need to make sure that your printer has paper and that it is turned on. I assumed the use of LPT1 as the printer port when I wrote this; please let me know if there is a need to code the program for any other porting. Option 4 will copy important information (the things shown in yellow in the color version of the program) to a file which you will name. Any valid DOS filename is permissible from a single letter or number to a seven letter filename connected by a period to a three letter file extension. You must use a little care as any file name you chose will be used. If there already exists a file of the same name, it will be overwritten. page 4 EXITING FROM THE PROGRAM To exit from the program, return to the MAIN MENU and chose option 6. COLOR AND MONOCHROME VERSIONS The program can be loaded in either color or monochrome. To load the program in color, at the DOS prompt, type "days" and hit the enter or return key. To load the program in monochrome, at the DOS prompt, type "days m" and hit the enter or return key. Both versions are substantively identical, differing only in visual appearance. The monochrome version is simply the color version with the ANSI escape sequences turned off. COLOR VERSION OF "Days-Calculator". The color version of the program was done in a simple fashion by using ANSI escape sequences to change foreground and background colors and intensities. For these escape sequences to work, you must have the file "ansi.sys" loaded. If "ansi-sys" is not loaded, the screen attributes will not be changed, and you will get what look like garbage characters (the literal output of the ansi escape sequences) littering the screen and upsetting the otherwise neat spacing of the menus, input, and output. The program will still work but it will look funny. To remedy this, and to make the program work in color, you need to install the "ansi.sys" file. The "ansi.sys" file is one of the several DOS files and is either located on your hard drive already or can be copied from your original DOS disks. You should copy "ansi.sys" to the ROOT directory of your hard disk (or to your BOOT disk if you are working from a floppy disk system). In the alternative, you could have a path set up from your ROOT directory to the directory containing "ansi.sys". Once "ansi.sys" is in the ROOT directory, or is available to the ROOT directory via a path command, it can then be loaded by means of your "config.sys" file. "Config.sys", or system configuration, configures or sets up your system every time your computer is started. You will be either modifying your existing "config.sys" file or creating one. Go to your ROOT directory and type "DIR CONFIG.SYS" (RETURN) to see if you have a "config.sys" file already. If you do, you can see what is in it with the following command: "TYPE CONFIG.SYS" (RETURN). You will need to add the following line to the "config.sys" file to make "ansi.sys" work: "DEVICE = ANSI.SYS". You can use any ASCII based word processor or text editor to modify the file and add the line given above. You can also create or modify the file directly from the keyboard by using the "COPY CON:(FILENAME)" command. COPY CON stands for copy console. The console is the keyboard. What you are literally telling the computer to do is to copy what you are typing from the keyboard directly to a file. You start with the page 5 "COPY CON:(FILENAME)" command (which includes the name of the file which you are creating. You then type the body of the file, line by line, and conclude on a new line by typing "CONTROL-Z, RETURN". "CONTROL-Z" causes the lines you have typed on the screen to be written to the file you have designated. For example, to create a new config.sys file, including "ansi.sys", you could type the following: copy con:config.sys files = 20 buffers = 20 device = ansi.sys CTRL-Z (RETURN) This would create a new "config.sys" file. You would have to restart your computer to have the new "config.sys" take effect. If you already have a config.sys file, you could use the TYPE command as describe above to show what is already in it, or you could use the follow command to copy your existing "config.sys" file to the printer: COPY CONFIG.SYS PRN (RETURN). This would print out a copy of your existing "config.sys" file. You could then use COPY CON:CONFIG.SYS to retype what was already in your "config.sys" file and to add the line "device = ansi.sys". Remember, anytime you change your "config.sys" file, you have to reboot your computer for the changes to take effect. MONOCHROME VERSION OF "Days-Calculator". In case you prefer monochrome, or for some reason you are unable to install "ansi.sys" on your computer, you can always run the program in the monochrome mode at the DOS prompt by typing "days m" (return). This runs the program but turns off the ANSI escape sequences that manipulate the color and intensity changes. DATE ENTRY VALIDATION The program has been written to prevent entry of an invalid date. When an entire date has been entered (month, day, and year) the date is checked for validity. If you have entered an invalid date (4/31/1991 for instance - remember, April only has 30 days!) you will be presented with an error message advising you what it was that you did wrong. You will then be kicked back to the MAIN MENU where you can begin again. I learned something that I didn't know while building this program. Only certain centennial years are leap years. If you think about it, every centennial year 1900, 2000, 2100, etc., falls within the normal four year leap year progression. However only every fourth centennial year, those evenly divisible by 400, are leap years. The reason for this is basically the same reason that we have leap years. The reason that we have leap years is because the earth takes a little more than 365 days to make a complete circle around the sun. In rough terms, it takes 365 and 1/4 days to page 6 make a complete circuit about the sun. If corrections were not made for that roughly 1/4 day per year, the seasons would slowly shift as the Calendar got out of sync with the earth's rotation. The key to the handling of Centennial leap years is due to the fact that the 1/4 day is rough and not exact. It actually takes slightly less than 365 and 1/4 days for the earth to make its complete circuit of the sun. The Centennial year leap years (and Centennial year non-leap years) are a further means of adjusting to keep the Calendar in sync with the seasons. Since it is a much smaller variance than 1/4 day, this adjustment needs to be made far less often than the four year leap year adjustment. HOW THE PROGRAM WORKS What we use as a daily calendar is a Gregorian calendar (see historical notes below). Due to the way that Gregorian dates are expressed, and due to the differing number of days in given months and in given years, it is not a simple matter to add or subtract dates or to calculate the number of days between two Gregorian dates. Fortunately it is possible to convert a Gregorian date to a Julian date. Julian dates are sequential day numbers that are incremented by 1 each day, based upon a starting date centuries ago. A Julian date can also be converted back to a Gregorian date. Once you have converted two Gregorian dates to Julian dates, it is a simple matter to subtract one number from the other to come up with an integer difference in days between the two dates. In a similar fashion, once you convert a Gregorian date to a Julian date, you can easily add or subtract any number of days to come up with another Julian date which can then be converted back to a Gregorian date. Because Gregorian dates are converted to Julian dates, it is absolutely necessary to include all digits of the Gregorian calendar year when inputting a date. It would be possible to write the program to require entry of only the last two digits of the year (assuming the first two digits to be 19__). This would however limit the utility of the program to a single century. By requiring entry of all digits for the year, it makes the program's scope almost limitless. It will go almost forever into the future (until you exceed the ability of the "C" language in its ability to handle a long integer value which might well take us past the end of mankind). It can only go back in time to the year A.D. (Anno Domini) zero as it has not been programmed to deal with negative year numbers. This could be done but I didn't see any practical application for it. If someone can suggest a practical application, I would consider adding in the capability to deal with negative Gregorian year numbers. page 7 HISTORICAL NOTES ON CALENDARS (from Grolier's Electronic Encyclopedia) Ancient Calendars The earliest complete calendars were probably based on lunar observations. The Moon's phases occur over an easily observed interval, the month; religious authorities declared a month to have begun when they first saw the new crescent Moon. During cloudy weather, when it was impossible to see the Moon, the beginning of the month was determined by calculation. The interval from new moon to new moon, called a synodic month, is about 29.53 days. Hence, calendar months contained either 29 or 30 days. Twelve lunar months, which total 354.36 days, form a lunar year, almost 11 days shorter than a tropical year. A lunar year is not suitable for agricultural purposes. To keep in step with the Sun, lunar-solar calendars were formed by adding an additional (leap) month when the observation of crops made it seem necessary. Hundreds of such calendars, with variations, were formed at various times in such different areas as Mesopotamia, Greece, Rome, India, and China. The month was not always based on the phases of the Moon; the Mayan calendar divided the year into 18 20-day months, with a 5-day period at the end. Romans, during the late republic, used various lunar-solar calendars. These calendars were supposedly based only on observation, but in fact they were influenced by political considerations. The Roman calendar was in error by several months during the reign of Julius Caesar, who recognized the need for a stable, predictable calendar and formed one with the help of an astronomer, Sosigenes. The year 46 BC was given 445 days, to compensate for past errors, and every common year thereafter was to have 365 days. Every fourth year, starting with 45 BC, was to be designated a leap year of 366 days, during which February, which commonly had 28 days, was extended by one day. The rule was not correctly applied, but the calendar was corrected by Augustus Caesar by AD 8. Gregorian Calendar The Julian leap-year rule created 3 leap years too many in every period of 385 years. As a result, the actual occurrence of the equinoxes and solstices drifted away from their assigned calendar dates. As the date of the spring equinox determines that of Easter, the church was concerned, and Pope Gregory XIII, with the help of an astronomer, Christopher Clavius (1537-1612), introduced what is now called the Gregorian calendar. Wednesday, Oct. 4, 1582 (Julian), was followed by Thursday, Oct. 15, 1582 (Gregorian); leap years occur in years exactly divisible by four, except that years ending in 00 must be divisible by 400 to be leap years. Thus, 1600, 1984, and 2000 are leap years, but 1800 and 1900 are not. page 8 The Gregorian civil calendar is a solar calendar, calculated without reference to the Moon. However, the Gregorian calendar also includes rules for determining the date of Easter and other religious holidays, which are based on both the Sun and the Moon. The Gregorian calendar was quickly adopted by Roman Catholic countries. Other countries adopted it later, sometimes choosing only the civil part. It was not adopted by the Soviet Union until 1918; Turkey did not adopt it until 1927. Year Beginning The year used to begin at different times in different localities. The Roman year began in March; December, whose name is derived from the Latin word for "ten," was the tenth month of the year. In 153 BC, Roman consuls began taking office on January 1, which became the beginning of the year. This practice was retained in the Julian and Gregorian calendars, although other starting dates continued to be used; England and its colonies, for example, used March 25 and the Julian reckoning until 1752. Thus, George Washington was officially born on Feb. 11, 1731, Old Style (O.S.); this is Feb. 22, 1732, Gregorian, or New Style (N.S.). Week The Babylonians used a nonastronomical, 7-day interval, the week, which was adopted by the Jews. The seventh day, the Sabbath, was given a religious significance. Independently, the Romans associated a cycle of 7 days with the Sun, the Moon, and the five known planets. Their names became attached to the days of the week: Sunday (dies solis, "Sun's day"), Monday (dies lunae, " Moon's day"), and Saturday (dies Saturni, "Saturn's day") retain their names derived directly from the Roman culture, and Tuesday ("Tiw's day"), Wednesday ("Woden's day"), Thursday ("Thor's day"), and Friday ("Frigg's day") are derived from the Germanic equivalents of Mars, Mercury, Jupiter, and Venus, respectively. Year In ancient calendars, years were generally numbered according to the year of a ruler's reign. About AD 525, a monk named Dionysius Exiguus suggested that years be counted from the birth of Christ, which was designated AD (anno Domini, "the year of the Lord") 1. This proposal came to be adopted throughout Christendom during the next 500 years.^ The year before AD 1 is designated 1 BC (before Christ). Dionysius had referred the year of Christ's birth to other eras. Modern chronology, however, places the event at about 4 BC. The 1st century of the Christian Era began in AD 1, the 2d in AD 101; the 21st will begin in 2001. page 9 THE NAMES OF THE MONTHS January: named for Janus, protector of doorways. February: named for Februalia, a time period when sacrifices were made to atone for sins. March: named for Mars, the god of war, presumably signifying that the campaigns interrupted by the winter could be resumed. April: from aperire, Latin for "to open" (buds). May: named for Maia, the goddess of growth of plants. June: from juvenis, Latin for "youth". July: named for Julius Caesar. August: named for Augustus, the first Roman emperor. September: from septem, Latin for "seven". October: from octo, Latin for "eight". November: from novem, Latin for "nine". December: from decem, Latin for "ten". NOTE: The earliest Latin calendar was a 10-month one; thus September was the seventh month, October, the eighth, etc. July was originally called Quintilis, as the fifth month; August was originally called Sextilis, as the sixth month. Bibliography: Archer, Peter, The Christian Calendar and the Gregorian Reform (1941); Asimov, Isaac, The Clock We Live On (1963); Keane, Jerryl, Book of Calendars (1981); Philips, Alexander, The Calendar: Its History, Structure, and Improvement (1921); Watkins, Harold, Time Counts: The Story of the Calendar (1954); Wilson, P. W., The Romance of the Calendar (1937). COMMENTS, SUGGESTIONS, AND COMPLAINTS I have been teaching myself the "C" programming language and this program is my first attempt to use "C". It is more compact and elegant than QuickBasic which is what I have primarily used in the past. Please address any comments, suggestions, or complaints to the program author at the following address: Brian Allen Kuehn 1524 Upper Spring Bay Road East Peoria, Illinois 61611 page 10 ORDER FORM Brian Allen Kuehn 1524 Upper Spring Bay Road East Peoria, Illinois 61611 I enclose my personal check, cashiers check, or money order for $12.00, made payable to Brian Allen Kuehn. Please send my registered copy of "DAYS-CALCULATOR"tm to: _____________________________________ Name _____________________________________ Street Address _____________________________________ City, State, Zip _____________________________________ Phone (optional) I understand that I will receive a 5.25" disk with a clean copy of the program. My name will be added to the customer list for notification regarding any updates to "DAYS-CALCULATOR"tm. I will be assigned my own unique serial number: example - #27135008713.