Programming interface to the Swiss Ephemeris - programmiastral.com

Swiss Ephemeris 40
19. Using the DLL with Borland Delphi and C++ Builder
19.1 Delphi 2.0 and higher (32-bit)
The information in this section was contributed by Markus Fabian, Bern, Switzerland.
In Delphi 2.0 the declaration of the function swe_calc() looks like this:
xx : Array[0..5] of double;
function swe_calc (tjd : double; // Julian day number
ipl : Integer; // planet number
iflag : Longint; // flag bits
var xx[0] : double;
sErr : PChar // Error-String;
) : Longint; stdcall; far; external 'swedll32.dll' Name '_swe_calc@24';
A nearly complete set of declarations is in file \sweph\delphi2\swe_d32.pas.
A small sample project for Delphi 2.0 is also included in the same directory (starting with release 1.25 from June
1998). This sample requires the DLL to exist in the same directory as the sample.
19.2 Delphi 1.0 (16-bit)
The 16-bit Delphi compiler belongs to the class of compilers we call ‘brain damaged’. There is a problem with
functions returning a double as the function value, e.g. swe_julday(). These functions do not work. There are
twin functions provided in the DLL which use an additional paramater to return the double, like
swe_julday_d(). These twin functions use also always pointers to double instead of double for all double
parameters.
In the directory sweph\src\delphi1 a complete small sample program written with Delphi 1.0 is provided. It
demonstrates the correct declaration and use of the most important SwissEph functions.
Besides, there is a file swe_de16.pas, which contains all function declarations for Delphi 1.0 and the Swisseph
constants such as flag bits and planet indices. You can copy them into your Pascal code.
Here are a few sample declarations:
Var xx
: Array[0..5] of double; serr : Array[0..255] of Char;
function swe_deltat_d(var tjd: double; var deltat: double): integer; far; external 'swedll16';
function swe_calc(
tjd: double; {Julian day number }
ipl: Integer; {planet number }
iflag: Longint; {flag bits }
var xx: double; {address of first array element}
sErr: Pchar {Error-String; }
): Longint; far; external 'swedll16';
function swe_julday_d(
year: Integer;
month: Integer;
day: Integer;
var hour: double;
gregflag: Integer;
var tjd: double
) : Integer; far; external 'swedll16';
Remember: With Delphi 1, do not use functions which have a double function value. Also note that, in Pascal,
double pointer parameters need to be defined as ‘var’(by reference, not by value).
19.3 Borland C++ Builder
Borland C++ Builder (BCB) does not understand the Microsoft format in the library file SWEDLL32.LIB; it
reports an OMF error when this file is used in a BCB project. The user must create his/her own LIB file for BCB
with the utility IMPLIB which is part of BCB.