一个有关dll的问题!(100分)

hfjacklee · 2002-03-29

[

]这是我生成的dll的源程序: library P_smalltobig; { 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   SysUtils,   Classes; {$R *.RES} function SmallTOBig(small:real):string;stdcall; var SmallMonth,BigMonth:string;     wei1,qianwei1:string[2];     //wei,     qianwei,dianweizhi,qian:integer; begin     {------- 修改参数令值更精确 -------}     {小数点后的位数，需要的话也可以改动该值}     qianwei:=-2;     {转换成货币形式，需要的话小数点后加多几个零}     Smallmonth:=formatfloat('0.00',small);     {---------------------------------}     dianweizhi :=pos('.',Smallmonth);{小数点的位置}     {循环小写货币的每一位，从小写的右边位置到左边}     for qian:=length(Smallmonth) downto 1 do     begin       {如果读到的不是小数点就继续}       if qian<>dianweizhi then       begin         {位置上的数转换成大写}         case strtoint(copy(Smallmonth,qian,1)) of         1:wei1:='壹'; 2:wei1:='贰';         3:wei1:='叁'; 4:wei1:='肆';         5:wei1:='伍'; 6:wei1:='陆';         7:wei1:='柒'; 8:wei1:='捌';         9:wei1:='玖'; 0:wei1:='零';         end;         {判断大写位置，可以继续增大到real类型的最大值，可是谁有那么多钱}         case qianwei of         -3:qianwei1:='厘';         -2:qianwei1:='分';         -1:qianwei1:='角';         0 :qianwei1:='元';         1 :qianwei1:='拾';         2 :qianwei1:='佰';         3 :qianwei1:='千';         4 :qianwei1:='万';         5 :qianwei1:='拾';         6 :qianwei1:='佰';         7 :qianwei1:='千';         8 :qianwei1:='亿';         9 :qianwei1:='十';         10:qianwei1:='佰';         11:qianwei1:='千';         end;       inc(qianwei);       BigMonth :=wei1+qianwei1+BigMonth;{组合成大写金额}     end;     end;    //SmallTOBig:=BigMonth;    result:=bigmonth; end; exports   SmallTOBig index 0; begin end. 问题是这样的,在程序中调用此段dll时运行一切正常函数也正确执行,但是就会在执行完毕后报"invalid pointer operation"的错误.但是我把这段函数直接写在程序里调用就没有问题.不知错在哪里,望高手赐教!!谢了 [

]

delphi · 2002-03-29

呵呵，看看你Unit前面的注释。 { 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. } 如果你使用String作为参数或返回值的话，一定要用ShareMem作为第一个单元。

最好还是用PChar，ShortString传递参数吧。

yansh · 2002-03-29

delphi的 string类型是delphi独有的，与微软的开发工具的string类型不同，建议 用PChar类型回传参数，Pchar类似C里的LPSTR。这样可以把你的dll用于VB,VC,等其他 开发工具，通用性较强。 给你一个例子 DLL部分 Function GetIdeDiskSerialNumber(Ret_Number: pChar):Boolean;export;stdcall; begin    ........ end; exports     GetIdeDiskSerialNumber; 调用部分： procedure TForm1.Button1Click(Sender: TObject); var     ss:string;     ssss:boolean; begin     setlength(ss,200);     ssss:=GetIdeDiskSerialNumber(pchar(ss));     if ssss then        label1.Caption :=ss     else         showmessage('error'); end;

hfjacklee · 2002-03-29

library P_smalltobig; { 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   SysUtils,   Classes; {$R *.RES} function SmallTOBig(small:real)

char;stdcall; var SmallMonth,BigMonth:string;     wei1,qianwei1:string[2];     //wei,     qianwei,dianweizhi,qian:integer; begin     {------- 修改参数令值更精确 -------}     {小数点后的位数，需要的话也可以改动该值}     qianwei:=-2;     {转换成货币形式，需要的话小数点后加多几个零}     Smallmonth:=formatfloat('0.00',small);     {---------------------------------}     dianweizhi :=pos('.',Smallmonth);{小数点的位置}     {循环小写货币的每一位，从小写的右边位置到左边}     for qian:=length(Smallmonth) downto 1 do     begin       {如果读到的不是小数点就继续}       if qian<>dianweizhi then       begin         {位置上的数转换成大写}         case strtoint(copy(Smallmonth,qian,1)) of         1:wei1:='壹'; 2:wei1:='贰';         3:wei1:='叁'; 4:wei1:='肆';         5:wei1:='伍'; 6:wei1:='陆';         7:wei1:='柒'; 8:wei1:='捌';         9:wei1:='玖'; 0:wei1:='零';         end;         {判断大写位置，可以继续增大到real类型的最大值，可是谁有那么多钱}         case qianwei of         -3:qianwei1:='厘';         -2:qianwei1:='分';         -1:qianwei1:='角';         0 :qianwei1:='元';         1 :qianwei1:='拾';         2 :qianwei1:='佰';         3 :qianwei1:='千';         4 :qianwei1:='万';         5 :qianwei1:='拾';         6 :qianwei1:='佰';         7 :qianwei1:='千';         8 :qianwei1:='亿';         9 :qianwei1:='十';         10:qianwei1:='佰';         11:qianwei1:='千';         end;       inc(qianwei);       BigMonth :=wei1+qianwei1+BigMonth;{组合成大写金额}     end;     end;    //SmallTOBig:=BigMonth;    result:=pchar(bigmonth); end; exports   SmallTOBig index 0; begin end. 我将程序做了修改,将返回值变为pchar但是,更严重,无发运行了!

delphi · 2002-03-29

PChar要申请空间的啊，将DLL函数改成： procedure SmallTOBig(small:real; Result: PChar);stdcall; 主程序中： procedure Test; var   Result: array [0..200] of char; begin   SmallToBig(10, Result); end; 这样写才行。

hfjacklee · 2002-03-29

还是不行,越改越乱!按你所说该后竟然编译都报错"identifier redeclared:'result'[

] 怎么办?我还是要函数不要过程!难道dfw们没有办法?我已经写的很清楚了!请把我的程序拷贝后试运行!

delphi · 2002-03-29

晕，为什么一定要函数？ 下面这个程序，多线程环境下会有问题： DLL: ----------------- library P_smalltobig; { 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   SysUtils,   Classes; {$R *.RES} var   OutString: array[0..255] of Char; function SmallTOBig(small:real): PChar; stdcall; var SmallMonth,BigMonth:string;     wei1,qianwei1:string[2];     //wei,     qianwei,dianweizhi,qian:integer; begin     {------- 修改参数令值更精确 -------}     {小数点后的位数，需要的话也可以改动该值}     qianwei:=-2;     {转换成货币形式，需要的话小数点后加多几个零}     Smallmonth:=formatfloat('0.00',small);     {---------------------------------}     dianweizhi :=pos('.',Smallmonth);{小数点的位置}     {循环小写货币的每一位，从小写的右边位置到左边}     for qian:=length(Smallmonth) downto 1 do     begin       {如果读到的不是小数点就继续}       if qian<>dianweizhi then       begin         {位置上的数转换成大写}         case strtoint(copy(Smallmonth,qian,1)) of         1:wei1:='壹'; 2:wei1:='贰';         3:wei1:='叁'; 4:wei1:='肆';         5:wei1:='伍'; 6:wei1:='陆';         7:wei1:='柒'; 8:wei1:='捌';         9:wei1:='玖'; 0:wei1:='零';         end;         {判断大写位置，可以继续增大到real类型的最大值，可是谁有那么多钱}         case qianwei of         -3:qianwei1:='厘';         -2:qianwei1:='分';         -1:qianwei1:='角';         0 :qianwei1:='元';         1 :qianwei1:='拾';         2 :qianwei1:='佰';         3 :qianwei1:='千';         4 :qianwei1:='万';         5 :qianwei1:='拾';         6 :qianwei1:='佰';         7 :qianwei1:='千';         8 :qianwei1:='亿';         9 :qianwei1:='十';         10:qianwei1:='佰';         11:qianwei1:='千';         end;       inc(qianwei);       BigMonth :=wei1+qianwei1+BigMonth;{组合成大写金额}     end;     end;    //SmallTOBig:=BigMonth;    //result := bigmonth;    StrPCopy(OutString, Bigmonth);    Result := @OutString[0]; end; exports   SmallTOBig index 0; begin end. 主程序： ------------ unit testunit; interface uses   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,   Dialogs, StdCtrls; type   TForm1 = class(TForm)     Button1: TButton;     procedure Button1Click(Sender: TObject);   private     { Private declarations }   public     { Public declarations }   end; var   Form1: TForm1; implementation {$R *.dfm} type   Tsmalltobig = function (small:real): PChar; stdcall; procedure TForm1.Button1Click(Sender: TObject); var   handle: THandle;   proc: Tsmalltobig; begin   handle := loadlibrary('P_smalltobig');   proc := getprocaddress(handle, 'SmallTOBig');   showmessage(strpas(Proc(13230.23))); end; end. 用短字符串也可以，不过只能用Delphi调用。 DLL ---------- library P_smalltobig; { 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   SysUtils,   Classes; {$R *.RES} type   CString = String[255]; function SmallTOBig(small:real): CString; stdcall; var SmallMonth,BigMonth:string;     wei1,qianwei1:string[2];     //wei,     qianwei,dianweizhi,qian:integer; begin     {------- 修改参数令值更精确 -------}     {小数点后的位数，需要的话也可以改动该值}     qianwei:=-2;     {转换成货币形式，需要的话小数点后加多几个零}     Smallmonth:=formatfloat('0.00',small);     {---------------------------------}     dianweizhi :=pos('.',Smallmonth);{小数点的位置}     {循环小写货币的每一位，从小写的右边位置到左边}     for qian:=length(Smallmonth) downto 1 do     begin       {如果读到的不是小数点就继续}       if qian<>dianweizhi then       begin         {位置上的数转换成大写}         case strtoint(copy(Smallmonth,qian,1)) of         1:wei1:='壹'; 2:wei1:='贰';         3:wei1:='叁'; 4:wei1:='肆';         5:wei1:='伍'; 6:wei1:='陆';         7:wei1:='柒'; 8:wei1:='捌';         9:wei1:='玖'; 0:wei1:='零';         end;         {判断大写位置，可以继续增大到real类型的最大值，可是谁有那么多钱}         case qianwei of         -3:qianwei1:='厘';         -2:qianwei1:='分';         -1:qianwei1:='角';         0 :qianwei1:='元';         1 :qianwei1:='拾';         2 :qianwei1:='佰';         3 :qianwei1:='千';         4 :qianwei1:='万';         5 :qianwei1:='拾';         6 :qianwei1:='佰';         7 :qianwei1:='千';         8 :qianwei1:='亿';         9 :qianwei1:='十';         10:qianwei1:='佰';         11:qianwei1:='千';         end;       inc(qianwei);       BigMonth :=wei1+qianwei1+BigMonth;{组合成大写金额}     end;     end;    //SmallTOBig:=BigMonth;    result := bigmonth; end; exports   SmallTOBig index 0; begin end. 主程序： ------------- unit testunit; interface uses   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,   Dialogs, StdCtrls; type   TForm1 = class(TForm)     Button1: TButton;     procedure Button1Click(Sender: TObject);   private     { Private declarations }   public     { Public declarations }   end; var   Form1: TForm1; implementation {$R *.dfm} type   CString = String[255];   Tsmalltobig = function (small:real): CString; stdcall; procedure TForm1.Button1Click(Sender: TObject); var   handle: THandle;   proc: Tsmalltobig; begin   handle := loadlibrary('P_smalltobig');   proc := getprocaddress(handle, 'SmallTOBig');   showmessage(Proc(13230.23)); end; end.

hfjacklee · 2002-04-16

^_^，这个问题的正确答案我总算找到了！就是在调用此dll的应用程序中的dpr的uses段的首位加入sharemem就可以了！啊哈哈哈哈哈

hfjacklee · 2002-04-16

散分啦，二位高手请接招！！多谢了！

一个有关dll的问题!(100分)

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