SetWindowLong(hwnd,GWL_USERDATA,lParam); puser1=(PUserInfo)GetWindowLong(hwnd,GWL_USERDATA);

typedef struct _usersInfo
{
	char userName[256];
	char passWord[256];
}UserInfo,*PUserInfo;

void Main_OnCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
    switch(id)
    {
        case IDC_OK:
		{
			//MessageBox(hwnd,TEXT("欢迎访问如鹏网 www.RuPeng.com 大学生计算机学习社区"),TEXT("问好"),MB_OK);
			HINSTANCE hInstance;
			hInstance=(HINSTANCE)GetWindowLong(hwnd,GWL_HINSTANCE);
			//DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1), NULL, Dlg1_Proc);	
			UserInfo user1={"yzk","12345"};
			DialogBoxParam(hInstance,MAKEINTRESOURCE(IDD_DIALOG1),hwnd,Dlg1_Proc,(long)&user1);
			MessageBox(hwnd,user1.userName,user1.passWord,MB_OK);
		}
        break;
        default:
		break;
    }
}

//
BOOL Dlg1_OnInitDialog(HWND hwnd, HWND hwndFocus, LPARAM lParam)
{
//	char buf[256];
	//MessageBox(hwnd,itoa((int)lParam,buf,10),"",MB_OK);
	PUserInfo puser1;
	puser1=(PUserInfo)lParam;
	//MessageBox(hwnd,puser1->userName,puser1->passWord,MB_OK);
	SetDlgItemText(hwnd,IDC_USERNAME,puser1->userName);
	SetDlgItemText(hwnd,IDC_PASSWORD,puser1->passWord);
	SetWindowLong(hwnd,GWL_USERDATA,lParam);
    return TRUE;
}

void Dlg1_OnCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
    switch(id)
    {
	case IDOK:
		{
		PUserInfo puser1;
        puser1=(PUserInfo)GetWindowLong(hwnd,GWL_USERDATA);		
		/*
		char buf[256];
		wsprintf(buf,"%d,%d,%d",sizeof(puser1),sizeof(puser1->userName),sizeof(puser1->passWord));
		MessageBox(hwnd,buf,"",MB_OK);
		//*/
		GetDlgItemText(hwnd,IDC_USERNAME,puser1->userName,sizeof(puser1->userName));
		GetDlgItemText(hwnd,IDC_PASSWORD,puser1->passWord,sizeof(puser1->passWord));
		EndDialog(hwnd, 0);
		}
        break;
	default:
		break;
    }
}