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Delphi ShareMem在dll中使用

千里之行_12 2017-05-06 22:42:06 浏览39 评论0

string dll delphi ShareMem在dll中使用

摘要： Delphi ShareMem在dll中使用

dll项目

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  System.ShareMem,  System.SysUtils,  System.Classes,  Winapi.Windows;//简繁体装换函数function Cn2Big(CnStr: string): string; stdcall ;var  Len: Integer;begin  Len := Length(CnStr);  SetLength(Result, Len);  LCMapString(GetUserDefaultLCID, LCMAP_TRADITIONAL_CHINESE, PChar(CnStr), Len, PChar(Result), Len);end;function Big2Cn(bigStr: string): string; stdcall ;var  Len: Integer;begin  Len := Length(bigStr);  SetLength(Result, Len);  LCMapString(GetUserDefaultLCID, LCMAP_SIMPLIFIED_CHINESE, PChar(bigStr), Len, PChar(Result), Len);end;{$R *.res}exports  Cn2Big,  Big2Cn;beginend.

在项目中第一种调用方式：

type  TForm4 = class(TForm)    Button1: TButton;    edt1: TEdit;    edt2: TEdit;    Button2: TButton;    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }  end;var  Form4: TForm4;function Cn2Big(CnStr: string): string; stdcall ; external 'Project2.dll';implementation{$R *.dfm}procedure TForm4.Button1Click(Sender: TObject);begin  edt2.Text :=  Cn2Big(edt1.Text);end;

这种调用方式在dll和项目中都不用shareMem，不爆异常。

第二种调用方式（动态加载dll）：

procedure TForm4.Button2Click(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('Cn2Big'));    if not (@addc = nil) then    begin      edt2.Text :=  addc(edt1.Text);    end;  finally    FreeLibrary(hh);  end;end;

在dll和项目中都不用shareMem，报异常。

在dll和项目中都用shareMem，不抛异常。