DATE$()

Description

This function returns today's date as a string or returns a numeric value of the number of days passed since Jan 1, 1901. The numeric value allows using date$() for math operations.

Additionally, one form of date$() returns a string value of any date given.

Syntax

Today's date

These forms return a STRING with today's date formatted as shown.

date$()	spaces	Sep 21, 2010
date$("mm/dd/yyyy")		09/21/2010
date$("mm/dd/yy")		09/21/10
date$("yyyy/mm/dd")		2010/09/21

The last form is often used for sorting.

Days passed

These forms return the NUMBER of days passed from Jan 1, 1901 until today, or until the date given.

date$("days")	spaces	40075
date$("09/11/2001")		36778

Any date

This form returns a string representation of any date, given the number of days since 1/1/1901.

date$(40075)

spaces

09/21/2010

Additional formats for Run BASIC

date$("dd")	spaces	return day of month padded to 2 digits with leading zeros (eg. 07)
date$("ddd")		return abbreviated day of the week (eg. Wed)
date$("dddd")		return full day of the week (eg. Wednesday)
date$("mm")		return month number padded to 2 digits with leading zeros (eg. 03)
date$("mmm")		return abbreviated month name (eg. Mar)
date$("mmmm")		return full month name (eg. March)
date$("yy")		return last two digits of the year (eg. 07)
date$("yyyy")		return year and century (eg. 2007)

Hints

The result of date$() can be assigned to a variable. e.g. d$ = date$()

For database use, store dates in numeric format to save space and to make the dates immediately available for math operations. e.g. Searching records to find the newest or oldest date.

When using date$() with an included date, the date can take any of these formats:

date$("4/1/02")
date$("1/1/1901")
date$("April 1, 2002")
date$("Apr 1, 2002")

If only the last 2 digits of year are given, the first digits are assumed to be 20. e.g. "4/1/02" = "4/1/2002"

You can use date$ to easily check if entered date is valid:

print date$("09/31/2010")<> 0 '0 means invalid date

print date$("09/29/2010")<> 0 '1 means valid date

See Useful Functions

Example

Getting today's date

    print date$()
    print date$("mm/dd/yyyy")

    ' The date$() result can be assigned to a variable.
    d$ = date$("mm/dd/yyyy")
    print d$

Date$() math

' A simple use of math with date$(), and showing use of
' numeric variables holding the result of date$().
    input "Please enter your birthday as mm/dd/yyyy: ";bd$
    born = date$(bd$)      ' returns numeric format of birthday
    today = date$("days")  ' returns numeric form of today
    ' Do the math...
    daysOld = today - born
    print "Today, you are "; daysOld; " days old!"
    ' Check if correct result
    print "That is "; daysOld/365; " years."
    end

Useful Procedures

Check for Leap Year

Function IsLeapYear(year)
    ' returns 1, if the specified year is a leap year,
    ' 0 otherwise. year must include the century as in 1980

    IsLeapYear = date$("2/29/"; year) <> 0
End Function

Check for Valid Date

Function IsValidDate(d$)
    ' returns 1, if the date represented by d$ is valid, 0 if not

    IsValidDate = date$(d$) <> 0
End Function

Day of Week from Days

This takes the day as the number of days since Jan 1st, 1901

'examples of usage
print weekDayFrDay$(date$("days"))      'now
print weekDayFrDay$(date$("days")+1)    'tomorrow
print weekDayFrDay$(date$("days")-7)    'week ago
print date$(40000), weekDayFrDay$(40000)    'some random date

function weekDayFrDay$(d)
    w = (d + 2) mod 7
    weekDayFrDay$ = word$("Sunday Monday Tuesday Wednesday Thursday Friday Saturday", w+1)
end function

Day of Week from Date

This takes the day as a date.

'examples of usage
print weekDayfrString$("09/32/2010")    'invalid date
print weekDayfrString$("09/29/2010")    'valid date

function weekDayfrString$(d$)
    d = date$(d$)
    if d = 0 then
         weekDayfrString$ = "Invalid date ";d$
    else
        w = (d + 2) mod 7
        weekDayfrString$ = word$("Sunday Monday Tuesday Wednesday Thursday Friday Saturday", w+1)
    end if
end function