[fpc-pascal] Re: How to build .so with FPC and use it in C program?

[Seth Grover]

I do it all the time. It works fine in Linux as of 2.2.2. There was a
problem in 2.2.0 where initialization and finalization code of units
in your uses section wouldn't get called, but they do now.

------- test.lpr -------------------------------
library test;

{$mode objfpc}{$H+}

uses
  Classes, SysUtils;

  function SquareNumber(const input : integer) : integer; cdecl;
  begin
    writeln('libtest.so SquareNumber');
    result := input * input;
  end;

exports
  SquareNumber name 'SquareNumber';

begin
  writeln('libtest.so initialization');

end.
------------------------------------------------

------- ctest.c -------------------------------
#include <stdio.h>

int SquareNumber(const int input);

main()
{
  int input;
  int output;

  input = 4;
  output = SquareNumber(4);

  printf("%i squared is %i\n", input, output);
}
-----------------------------------------------

To build the .so:

fpc -Sgi -CX -Xs -XX -vewnhi -l -Fu. -olibtest.so test.lpr

To build the c program (make sure the .so is in your link path)

gcc -o ctest -ltest ctest.c

Then run it:

libtest.so initialization
libtest.so SquareNumber
4 squared is 16

-SG

========================
Computer over. Virus = very yes.

Seth Grover
sethdgrover[at]gmail[dot]com