remove_copy/remove_copy_if詳解

remove_copy:移除值為value的元素,并将處理後在容器複制到另一容器裡.

源碼:

                   // TEMPLATE FUNCTION remove_copy

template<class _InIt,

         class _OutIt,

         class _Ty> inline

         _OutIt _Remove_copy(_InIt _First, _InIt _Last,

                   _OutIt _Dest, const _Ty& _Val)

         {       // copy omitting each matching _Val

         for (; _First != _Last; ++_First)

                   if (!(*_First == _Val))

                            *_Dest++ = *_First;

         return (_Dest);

         }

有了remove這個函數,加上copy就完全搞定.

remove_copy_if:

                   // TEMPLATE FUNCTION remove_copy_if

template<class _InIt,

         class _OutIt,

         class _Pr> inline

         _OutIt _Remove_copy_if(_InIt _First, _InIt _Last,

                   _OutIt _Dest, _Pr _Pred)

         {       // copy omitting each element satisfying _Pred

         for (; _First != _Last; ++_First)

                   if (!_Pred(*_First))

                            *_Dest++ = *_First;

         return (_Dest);

         }

有了remove_copy這個函數,這個自然就是小菜一碟.

還是來看例子吧!

舉例:

template<typename T>

bool isTrue( T _val )

{

         return ( _val % 2 ) == 0;

}

int main()

{

         vector<int> vecInt;

         for ( int i = 0;i < 10;++ i)

         {

                   vecInt.push_back( i );

                   vecInt.push_back( 10 - i );

         }

         vector<int> vecNew;

         cout<<"vecInt value:\n";

         remove_copy( vecInt.begin(),vecInt.end(),ostream_iterator<int>( cout," ") ,2 );

         cout<<"\nvecInt remove value:\n";

         remove_copy_if( vecInt.begin(),vecInt.end(),ostream_iterator<int>( cout," ") ,isTrue<int> );

         system( "pause" );

         return 0;

}