递归在C++应用中的利与弊

序号

英文名

中文名

类型

说明

1

Id

权限ＩＤ

Int

2

ParentId

父权限ＩＤ

Int

用于指定父结点

3

Name

权限名称

Varchar(32)

4

IdCode

菜单项ＩＤ

int

权限与菜单项关联

     DWORD dwFunction = 0;       //功能ID

     HTREEITEM hItemLayer[5][2]; //用于保存当前正在操作的结点，用于回溯

     int nIdCollection[5][2];    //保留父层结点的ＩＤ，用于识别下一个结点的父层所属

     // 设置树根

     hItemLayer[0][0] = m_treeOperatorPermission.InsertItem(_T("权限设置"),3,3);

     m_treeOperatorPermission.SetItemData (hItemLayer[0][0] , dwFunction);

     hItemLayer[0][1] = hItemLayer[0][0];

     nIdCollection[0][0] = 0;    //父层ID

     nIdCollection[0][1] = 0;    //当前层ID

     int nCurParentLay = 0;

     CADORecordset collection(&m_conn);        //ADO对象，用于从数据库取出记录集

     CString strSQLString("select id ,ParentId , Name , IdCode from tbl_function order by id , parentid");

     if(collection.Open (strSQLString))

     {

         int nCount = collection.GetRecordCount ();

         CString strFunctionName;

         for(int i = 0;i <nCount;i ++)

         {

              //从数据库中取出结点数据

              collection.GetFieldValue ("Name" , strFunctionName);

              int nId;

              int nParentId;

              collection.GetFieldValue ("Id" , nId);

              collection.GetFieldValue ("ParentId" , nParentId);

              do

              {

                   //判断其保留的父结点是否一致，用于判断是否从当前插入子结点，还是从父结点插入子结点

                   if(nParentId == nIdCollection[nCurParentLay][0])

                   {

                       //向父层插入子结点，并保留当前结点数据，用于回溯

                       hItemLayer[nCurParentLay][1] = m_treeOperatorPermission.InsertItem ((LPCTSTR)strFunctionName , 0 , 1 , hItemLayer[nCurParentLay][0]);

                       nIdCollection[nCurParentLay][1] = nId;

                       m_treeOperatorPermission.SetHalfChecked (hItemLayer[nCurParentLay][1]);

                        dwFunction = nId;

                       m_treeOperatorPermission.SetItemData (hItemLayer[nCurParentLay][1] , dwFunction);

                   }

                   else if(nParentId == nIdCollection[nCurParentLay][1])

                   {

                       //在当前层建立子层

                       hItemLayer[nCurParentLay + 1][1] = m_treeOperatorPermission.InsertItem ((LPCTSTR)strFunctionName , 0 , 1 , hItemLayer[nCurParentLay][1]);

                       hItemLayer[nCurParentLay + 1][0] = hItemLayer[nCurParentLay][1];

                       nIdCollection[nCurParentLay + 1][0] = nParentId;

                       nIdCollection[nCurParentLay + 1][1] = nId;

                       m_treeOperatorPermission.SetChecked (hItemLayer[nCurParentLay + 1][1] , FALSE);

                       dwFunction = nId;

                       m_treeOperatorPermission.SetItemData (hItemLayer[nCurParentLay + 1][1] , dwFunction);

                       nCurParentLay ++;

                   }

                   else

                   {

                       //回溯，用于找到相匹配的父结点，便于插入结点

                       nCurParentLay --;

                       continue;

                   }

                   break;

              }while(true);

              collection.MoveNext ();

         }

         m_treeOperatorPermission.Expand (hItemLayer[0][0] , TVE_EXPAND);

     }

     collection.Close ();

     m_treeOperatorPermission.ClearALLCheck ();

     return 0;

long InitDefaultPermissionTree(int nParentId ,HTREEITEM hItem)

{

     CString strSQLString;

     strSQLString.Format ("select id , name from tbl_function where parentid = %d" , nParentId);

     CADORecordset collection(&m_conn);

     if(collection.Open (strSQLString))

     {

         //将所有数据取出

         CArray <int  , int >        nIdArray;

         CArray <CString , CString>  strNameArray;

         int nCount = collection.GetRecordCount ();

         for(int i = 0;i < nCount ;i ++)

         {

              int nId;

              CString strName;

              collection.GetFieldValue ("id" , nId);

              collection.GetFieldValue ("name" , strName);

              collection.MoveNext ();

              nIdArray.Add (nId);

              strNameArray.Add (strName);

         }

         collection.Close ();

          //将从数据库中取出的数据插入到树图上

         for(i = 0;i < nCount;i ++)

         {

              int nId = nIdArray.GetAt (i);

              HTREEITEM hSonItem = m_treeOperatorPermission.InsertItem (strNameArray.GetAt (i) , 0 , 0 , hItem);

              m_treeOperatorPermission.SetItemData (hSonItem , nId);

               //后面讲述采用m_TreeDataMap(CMap<int , int &  ,HTREEITEM, HTREEITEM&>)的目的

              m_TreeDataMap.SetAt(nId , hSonItem);

               //对当前结点进行递归插入子结点数据

              InitDefaultPermissionTree(nIdArray.GetAt (i) , hSonItem);

         }

     }

     return 0;

}

正常算法

Int Sum(int nMax)

{

       int nSum = 0;

       for(int I = 1;I <= nMax;I ++)

       {

              nSum += I;

       }

       return nSum;

}

递归算法

Int Sum(int nMax)

{

       if(nMax > 0)

       {

              return Sum(nMax – 1) + nMax;

       }

       else

       {

              return 0;