大大们好,小弟我的问题真多,又要麻烦您们了 让程式只执行一次,站内有很多的内容: class="code"> unit Unit2; interface uses Windows, SysUtils, TlHelp32; function MapGlobalData(const MapName: string; Size: Integer; var Ptr: Pointer): THandle; procedure ReleaseGlobalData(var Handle: THandle; var Ptr: Pointer); function IsGlobalDataExistent(const MapName: string): Boolean; implementation function MapGlobalData(const MapName: string; Size: Integer; var Ptr: Pointer): THandle; begin Result := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, Size, PChar(MapName)); if Result = 0 then if GetLastError = ERROR_ALREADY_EXISTS then begin Result := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, PChar(MapName)); if Result = 0 then Exit; end else Exit; Ptr := MapViewOfFile(Result, FILE_MAP_ALL_ACCESS, 0, 0, 0); if Ptr = nil then begin CloseHandle(Result); Result := 0; end; end; procedure ReleaseGlobalData(var Handle: THandle; var Ptr: Pointer); begin if Assigned(Ptr) then begin UnmapViewOfFile(Ptr); Ptr := nil; end; if Handle <> 0 then begin CloseHandle(Handle); Handle := 0; end; end; function IsGlobalDataExistent(const MapName: string): Boolean; var hMap: THandle; begin hMap := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, PChar(MapName)); Result := hMap <> 0; if Result then CloseHandle(hMap); end; 然后在BCB中把这个单元文件添加到工程中去(Project--->Add to Project),然后把该单元编译一下.在BCB的工程中修改为:

//---------------------------------------------------------------------------    #include 
#pragma hdrstop
USERES("Project1.res");
USEFORM("Unit1.cpp", Form1);
USEUNIT("Unit2.pas");
//---------------------------------------------------------------------------
#include "Unit2.hpp"
WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
{
        typedef struct{
          HWND AppWnd;
        } TSharedStruct, *PSharedStruct;            const char* MapName = "TestMap";            PSharedStruct GlobalPointer;
        THandle hMap;            if(IsGlobalDataExistent(MapName))
        {
            hMap = MapGlobalData(MapName,sizeof(TSharedStruct),Pointer(GlobalPointer));                if(IsIconic(GlobalPointer->AppWnd))
                ShowWindow(GlobalPointer->AppWnd,SW_RESTORE);
            else
                SetForegroundWindow(GlobalPointer->AppWnd);                ReleaseGlobalData(hMap,Pointer(GlobalPointer));                return 0;
        }            hMap = MapGlobalData(MapName,sizeof(TSharedStruct),Pointer(GlobalPointer));
        GlobalPointer->AppWnd = Application->Handle;            try
        {
                 Application->Initialize();
                 Application->CreateForm(__classid(TForm1), &Form1);
                 Application->Run();
        }
        catch (Exception &exception)
        {
                 Application->ShowException(&exception);
        }            ReleaseGlobalData(hMap,Pointer(GlobalPointer));
        return 0;
}
//---------------------------------------------------------------------------
用这样的方法很好的实现了只让程序执行一次,而且如果前一个程序副本是最小化时还能将其带到前面来.
但是我在把Unit2.pas转化为BCB单元文件时就出问题了
[code]
//---------------------------------------------------------------------------    #include 
#pragma hdrstop    #include "Unit3.h"    //---------------------------------------------------------------------------
HANDLE __fastcall MapGlobalData(AnsiString MapName,int Size,void * &Ptr)
{
        HANDLE hMapFile;
        char *szBuf;
        lstrcpy(szBuf,MapName.c_str());            hMapFile = CreateFileMapping(0xFFFFFFFF,NULL,PAGE_READWRITE,0,Size,szBuf);  //这有错误,我不知道该怎样改            if(hMapFile == 0)
        {
            if(GetLastError = ERROR_ALREADY_EXISTS)
            {
                hMapFile = OpenFileMapping(FILE_MAP_ALL_ACCESS,False,szBuf);    //同样的这也有错误
                if(hMapFile == 0)
                {
                    exit(EXIT_FAILURE);
                }
            }
            else exit(EXIT_FAILURE);
        }            Ptr = MapViewOfFile(hMapFile,FILE_MAP_ALL_ACCESS,0,0,0);
        if(Ptr == NULL)
        {
            CloseHandle(hMapFile);
            hMapFile = 0;
        }            return hMapFile;
}
void __fastcall ReleaseGlobalData(unsigned &Handle, void * &Ptr)
{
        //不知道C  中该怎样判断指针是否为空        
        >
不看不知道,一编译就有 >    人生在勤，不索何获？
        

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人生在勤，不索何获？