CODEWITHSUNDEEP
delphidelphi-2009
Emil_halim
Emil_halim

Reputation: 55

E2065: Unsatisfied forward or external declaration

i have a c function 'cGetLen' that i want to call it from delphi2009 but got the above titel Error.

any help please ?

here is the code

unit testpas;

interface

function dFunc():Integer ; stdcall; 


implementation


function cGetLen(str1, str2: PAnsiChar): Integer ; cdecl; external;


function dFunc():Integer ; stdcall; 
var
    fstr1: ANSIString;
    sstr2: ANSIString;
begin   
    fstr1 := 'hello';
    sstr2 := 'there';

    dFunc := cGetLen( PAnsiChar(fstr1), PAnsiChar(sstr2) );

end;

begin

end.

Upvotes: 0

Views: 1938

Answers (1)

David Heffernan
David Heffernan

Reputation: 612944

The first problem is that you are not linking an external object. You would need to include:

{$LINK cGetLen.obj} // or whatever the object file is called

somewhere in the unit.

Once you've done that you will probably face another problem because the C compiler will decorate the name of the function. Typically, for a cdecl function, by prefixing an underscore. So you would import the function like this:

function cGetLen(str1, str2: PAnsiChar): Integer ; cdecl; external name '_cGetLen';

or

function _cGetLen(str1, str2: PAnsiChar): Integer ; cdecl;

The other common problem you will face is that the C function calls other functions that cannot be resolved. They would need to be either implemented in separate object files that you linked, or implemented in your Pascal code.

Do bear in mind that I cannot see your C code, nor do I know how you compiled it. So, these problems may not afflict you, or indeed you may be facing other problems. An interop question like this really does demand full disclosure.

To be perfectly honest, you appear to be quite a long way from success here. I suggest you pause this task, and get a firm grasp of this subject matter. Start here: http://praxis-velthuis.de/rdc/articles/articles-cobjs.html

Upvotes: 4

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