Delphi在创建和使用DLL的时候如果使用到string，请引入ShareMem单元

library Project2;{ Important note about DLL memory management: ShareMem must be the
first unit in your library's USES clause AND your project's (select
Project-View Source) USES clause if your DLL exports any procedures or
functions that pass strings as parameters or function results. This
applies to all strings passed to and from your DLL--even those that
are nested in records and classes. ShareMem is the interface unit to
the BORLNDMM.DLL shared memory manager, which must be deployed along
with your DLL. To avoid using BORLNDMM.DLL, pass string information
using PChar or ShortString parameters. }uses
ShareMem,
SysUtils,
Classes,
Unit1 in 'Unit1.pas';{$R *.res}
exports
test;beginend.

unit Unit1;interface
function test(const input: string): string; stdcall;implementation
function test(input: string): string; stdcall;
begin
Result:= '我是DLL中的test函数，输入是：' + input;
end;
end.

program Project1;uses
ShareMem,
Forms,
Unit1 in 'Unit1.pas' {Form1};{$R *.res}begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.

unit Unit1;interfaceuses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;type
TForm1 = class(TForm)
btn1: TButton;
procedure btn1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;var
Form1: TForm1;implementation{$R *.dfm}procedure TForm1.btn1Click(Sender: TObject);
type
TAddc= function(const input: string): string; stdcall;
var
hh: THandle;
addc: TAddc;
begin
hh:= LoadLibrary('Project2.dll');
try
if hh<>0 then
@addc:= GetProcAddress(hh, PChar('test'));
if not (@addc = nil) then
begin
ShowMessage(addc('lsls'));
end;
finally
FreeLibrary(hh);
end;end;end.