The service class DateTime obtains the current date and time from the operating system
and converts them into a form that can be used for comparisons and arithmetic. In this
context date values are stored as Julian days since a specified start date, Dec 31,1967 by
default, and time values are stored as seconds since midnight. Note that since time is only
expressed in seconds no special operating system calls are needed to obtain it.
The DateTime_GetDateAndTime method obtains the current data and time from the
operating system and returns them in standard integer value form. The standard date value is
simply the number of days that have passed since a specified start date (see JulianZero). The
standard integer value form for time is simply the number of seconds since midnight. Its
parameters are as follows:
Parameter
Description
DateValue
returns the current date in standard form as described above.
TimeValue
returns the current local time in standard form as described above.
The DateTime_JulianToDate method converts a relative Julian value into its
corresponding date value -- day, month, year. The relative Julian value is simply the number
of days that have passed since a specified started date (see JulianZero). Its parameters are
as follows:
Parameter
Description
Julian
Specifies the relative Julian value for which the date value is desired.
Day
returns the day value, 1..31, of the decomposed date value.
Month
returns the month value, 1..12, of the decomposed date value.
Year
returns the year value of the decomposed date value.
The method DateTime_ToJulian
Prototype
int DateTime_ToJulian(int day,int month,int year);
The DateTime_ToJulian method converts a date value into its relative Julian
value. The relative Julian value is simply the number of days that have passed since a
specified started date (see JulianZero). Its parameters are as follows:
Parameter
Description
day
Specifies the day value of the date.
month
Specifies the month value of the date.
year
Specifies the year value of the date.
The method returns the number of days that have passed since the specified start date.