Figure out function argument from custom struct?

I have a function which takes a custom struct as the argument. how can I figure out what the argument should be? I know it is a date format of sorts... (C library imported to Objective-C...)

Struct:

typedef struct
{
    /** The number of day in the hebrew month (1..31). */
    int hd_day;
    /** The number of the hebrew month 1..14 (1 - tishre, 13 - adar 1, 14 - adar 2). */
    int hd_mon;
    /** The number of the hebrew year. */
    int hd_year;
    /** The number of the day in the month. (1..31) */
    int gd_day;
    /** The number of the month 1..12 (1 - jan). */
    int gd_mon;
    /** The number of 开发者_开发百科the year. */
    int gd_year;
    /** The day of the week 1..7 (1 - sunday). */
    int hd_dw;
    /** The length of the year in days. */
    int hd_size_of_year;
    /** The week day of Hebrew new year. */
    int hd_new_year_dw;
    /** The number type of year. */
    int hd_year_type;
    /** The Julian day number */
    int hd_jd;
    /** The number of days passed since 1 tishrey */
    int hd_days;
    /** The number of weeks passed since 1 tishrey */
    int hd_weeks;
} hdate_struct;

Function:

int
hdate_get_omer_day(hdate_struct const * h)
{
    int omer_day;
    hdate_struct sixteen_nissan;

    hdate_set_hdate(&sixteen_nissan, 16, 7, h->hd_year);
    omer_day = h->hd_jd - sixteen_nissan.hd_jd + 1;

    if ((omer_day > 49) || (omer_day < 0)) 
        omer_day = 0;

    return omer_day;
}

Trying to call this function, not sure what goes into the date. There are functions for converting Julian to Hebrew too, all taking or returning the the same struct.

What do i do to get the function's return value?

It looks like you want to input a Hebrew date. So, you have to figure our how to create one. Try googling for "hdate_struct" or "convert to hdate_struct" or the like.

Otoh, code rading the function Counting of the Omer, Jewish ritual during the function hdate_get_omer_day() it looks like it returns zeor if not during Omer and 1 to 49 if one of the 49 days of Omer (See wikipedia "forty-nine days between Passover and the Feast of Weeks").

You could try googling for code to calculate the Omer day (e.g "How To: Make Your Own Omer Counte" http://www.google.com.sg/url?sa=t&source=web&ct=res&cd=5&ved=0CBcQFjAE&url=http%3A%2F%2Fwww.myjewishlearning.com%2Fblog%2Fholidays%2Fhow-to-make-your-own-omer-counter%2F&rct=j&q=get+omer+Day&ei=awOvS5TvHIjGrAe_3vGmAQ&usg=AFQjCNGJh7Ydy-VkfwlyzTL_ELIkiqP25w)

"The remainder is left as an exercise for the reader".