replace/replace_if详解

replace:替换指定值的元素

                   //TEMPLATE FUNCTION replace

template<class _FwdIt,

         class_Ty> inline

         void_Replace(_FwdIt _First, _FwdIt _Last,

                   const_Ty& _Oldval,const _Ty& _Newval)

         {       // replace each matching _Oldval with _Newval

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

                   if(*_First == _Oldval)

                            *_First = _Newval;

         }

 

template<class _FwdIt,

         class_Ty> inline

         voidreplace(_FwdIt _First, _FwdIt _Last,

                   const_Ty& _Oldval,const _Ty& _Newval)

         {       // replace each matching _Oldval with _Newval

         _DEBUG_RANGE(_First, _Last);

         _Replace(_Unchecked(_First),_Unchecked(_Last),

                   _Oldval, _Newval);

         }

replace_if和前面的_if系列函数一样,提供返回值为bool的但参数函数.如果返回值为true,则替换.

         // TEMPLATEFUNCTION replace_if

template<class _FwdIt,

         class_Pr,

         class_Ty> inline

         void_Replace_if(_FwdIt _First, _FwdIt _Last, _Pr _Pred,const_Ty& _Val)

         {       // replace each satisfying _Pred with _Val

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

                   if(_Pred(*_First))

                            *_First = _Val;

         }

 

template<class _FwdIt,

         class_Pr,

         class_Ty> inline

         voidreplace_if(_FwdIt _First, _FwdIt _Last, _Pr _Pred,const_Ty& _Val)

         {       // replace each satisfying _Pred with _Val

         _DEBUG_RANGE(_First, _Last);

         _DEBUG_POINTER(_Pred);

         _Replace_if(_Unchecked(_First),_Unchecked(_Last),

                   _Pred, _Val);

         }

这两个函数的实现码很简单.这里不过多说明.

举例:

template<typenameT>

bool  isTrue( T _val )

{

         return( _val % 2 ) == 0;

}

int main()

{

         vector<int>vecInt;

         for ( int i = 0;i < 10;++ i)

         {

                   vecInt.push_back( i );

         }

         cout<<"vecIntsource:\n";

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

         replace(vecInt.begin(),vecInt.end(),2,1 );

         cout<<"\nvecIntreplace:\n";

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

 

         replace_if(vecInt.begin(),vecInt.end(),isTrue<int>,10);

         cout<<"\nvecIntreplace:\n";

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

         system( "pause");

         return0;

}