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Reference/es_date
The es_date interface provides date arithmetic functionality. This includes the ability to add or subtract days and months to a date, to take the difference in days between any two dates and to compute the day of the week that a particular date falls on.
The date calculator must be initialized with respect to a range of years via a call to es_date_init(). Only dates within this range are subsequently valid.
es_date can convert a date supplied in either composite (i.e. YYYYMMDD) or individual (seperate year, month and day) format to a date-id and back again. A date-id is an unsigned integer representing a date as the number of days from January 1st of the beginning year in the valid range.
Calendar days can be added to or subtracted from a date by simply adding to or subtracting from a date-id.
The interface functions are as follows:
| es_date_init | Initializes date calculator. |
|---|---|
| es_date_destroy | Destroys date calculator and cleans up resources. |
| es_date_getlowyear | Get lowest year in calculator range. |
| es_date_gethighyear | Get highest year in calculator range. |
| es_date_getid_c | Convert date in composite format (YYYYMMDD) to a date-id. |
| es_date_getid_i | Convert date in individual format (years, months and days) to a date-id. |
| es_date_addmonths | Add or subtract a number of months to a date-id. |
| es_date_getyear | Get year corresponding to a date-id. |
| es_date_getmonth | Get month corresponding to a date-id. |
| es_date_getday | Get day-of-month corresponding to a date-id. |
| es_date_getcomp | Convert date-id to a date in composite format (YYYYMMDD). |
| es_date_getdow | Get day-of-week corresponding to a date-id. |
| es_date_getmaxid | Get maximum valid date-id in calculator range. |