數組作為函數參數c到c＃的混淆

Question

我試圖用C＃編寫一個類，以使用dll的導出功能，但是我遇到了很多函數，這些函數具有數組作為函數參數，我不確定該如何處理。 下面是一個例子。

我將如何在C＃函數中使用它？ 具體如何處理iymdf []？

調用函數時會發生什么？

這看起來正確嗎？

[DllImport("libsofa.dll")]
public static extern int iauJdcalf(int ndp, double dj1, double dj2, ref int[] iymdf =       new int[4]);

例：

int __stdcall iauJdcalf(int ndp, double dj1, double dj2, int iymdf[4])
{
    int j, js;
    double denom, d1, d2, f1, f2, f;

    /* Denominator of fraction (e.g. 100 for 2 decimal places). */
    if ((ndp >= 0) && (ndp <= 9)) {
        j = 0;
        denom = pow(10.0, ndp);
    } else {
        j = 1;
        denom = 1.0;
    }

    /* Copy the date, big then small, and realign to midnight. */
    if (dj1 >= dj2) {
        d1 = dj1;
        d2 = dj2;
    } else {
        d1 = dj2;
        d2 = dj1;
    }
    d2 -= 0.5;

    /* Separate days and fractions. */
    f1 = fmod(d1, 1.0);
    f2 = fmod(d2, 1.0);
    d1 = floor(d1 - f1);
    d2 = floor(d2 - f2);

    /* Round the total fraction to the specified number of places. */
    f = floor((f1+f2)*denom + 0.5) / denom;

    /* Re-assemble the rounded date and re-align to noon. */
    d2 += f + 0.5;

    /* Convert to Gregorian calendar. */
    js = iauJd2cal(d1, d2, &iymdf[0], &iymdf[1], &iymdf[2], &f);
    if (js == 0) {
        iymdf[3] = (int) (f * denom);
    } else {
        j = js;
    }

    /* Return the status. */
    return j;
} 

功能文檔：

/*
**  - - - - - - - - - -
**   i a u J d c a l f
**  - - - - - - - - - -
**
**  Julian Date to Gregorian Calendar, expressed in a form convenient
**  for formatting messages:  rounded to a specified precision.
**
**  This function is part of the International Astronomical Union's
**  SOFA (Standards Of Fundamental Astronomy) software collection.
**
**  Status:  support function.
**
**  Given:
**     ndp       int      number of decimal places of days in fraction 
**     dj1,dj2   double   dj1+dj2 = Julian Date (Note 1)
**
**  Returned:
**     iymdf     int[4]   year, month, day, fraction in Gregorian
**                        calendar
**
**  Returned (function value):
**               int      status:
**                          -1 = date out of range
**                           0 = OK
**                          +1 = NDP not 0-9 (interpreted as 0)
**
**  Notes:
**
**  1) The Julian Date is apportioned in any convenient way between
**     the arguments dj1 and dj2.  For example, JD=2450123.7 could
**     be expressed in any of these ways, among others:
**
**             dj1            dj2
**
**         2450123.7           0.0       (JD method)
**         2451545.0       -1421.3       (J2000 method)
**         2400000.5       50123.2       (MJD method)
**         2450123.5           0.2       (date & time method)
**
**  2) In early eras the conversion is from the "Proleptic Gregorian
**     Calendar";  no account is taken of the date(s) of adoption of
**     the Gregorian Calendar, nor is the AD/BC numbering convention
**     observed.
**
**  3) Refer to the function iauJd2cal.
**
**  4) NDP should be 4 or less if internal overflows are to be
**     avoided on machines which use 16-bit integers.
**
**  Called:
**     iauJd2cal    JD to Gregorian calendar
**
**  Reference:
** 
**     Explanatory Supplement to the Astronomical Almanac,
**     P. Kenneth Seidelmann (ed), University Science Books (1992),
**     Section 12.92 (p604).
**
**  This revision:  2010 July 27
**
**  SOFA release 2010-12-01
**
**  Copyright (C) 2010 IAU SOFA Board.  See notes at end.
*/

Answer 1

從C＃聲明中刪除ref關鍵字，這是不正確的。 您還需要丟失聲明中的初始化，這是不支持的語法。 在進行調用之前初始化數組。

[DllImport("libsofa.dll")]
public static extern int iauJdcalf(int ndp, double dj1, double dj2, int[] iymdf);
...
    int[] arr = new int[] { 1, 2, 3, 4 };
    int retval = iauJdcalf(1, 2, 3, arr);

Answer 2

您將要進行標准的函數調用，具體取決於您在做什么。 函數定義僅聲明“這些是我的輸入”，然后在調用它時，必須提供實際值。 您無需重新創建函數def。

[DllImport("libsofa.dll")]
myReturn = iauJdcalf(1, 2.0, 2.0, [1,2,3,4]);

您的函數定義為返回一個int，因此我們使用myReturn變量捕獲它，您當然需要首先對其進行聲明。 然后，我們提供一個int，兩個double和一個數組。 您還可以傳遞這些類型的變量，請注意確保數組的大小與所需大小相同。

另外，注意指針！ 如果將變量傳遞給c，它將復制到函數中定義的局部變量。 如果給它一個指針，則需要在函數定義中聲明它，並意識到我們正在玩指針游戲。

Answer 3

太回答我自己的問題了，我認為會涉及到更多的Marshaling東西，但是下面的代碼給出了一個合理的輸出。

    [DllImport("libsofa.dll")]
    public static extern int iauJdcalf(int ndp, double dj1, double dj2,    [MarshalAs(UnmanagedType.LPArray, SizeConst = 4)] int[] iymdf);

以及這個：

    [DllImport("libsofa.dll")]
    public static extern int iauJdcalf(int ndp, double dj1, double dj2, int[] iymdf);