adjacen_find详解

adjacen_find:搜索给定区间中两个连续相等的元素

这个函数也以重载的形式给出了这两个函数.一个是默认的关系运算(==),一个是仿函数

//TEMPLATE FUNCTION adjacent_find

template<class_FwdIt>inline

         _FwdIt _Adjacent_find(_FwdIt _First,_FwdIt _Last)

         {       // find first matching successor

         if(_First != _Last)

                   for(_FwdIt _Firstb; (_Firstb = _First), ++_First != _Last; )//首先保存起始元素.然后和下一个                                                                                                         //元素进行比较.如果相等则返回之前保

                                                                                                                //存的那个元素,否则进行下次比较.

         //需要注意的是,这里用了一些技巧,首先是使用了逗号表达式,其次是使用++_First == _Last.

                            if (*_Firstb == *_First)

                                     return (_Firstb);

         return(_Last);

         }

 

template<class_FwdIt>inline

         _FwdIt adjacent_find(_FwdIt _First,_FwdIt _Last)

         {       // find first matching successor

         _DEBUG_RANGE(_First, _Last);

         return(_Rechecked(_First,

                   _Adjacent_find(_Unchecked(_First),_Unchecked(_Last))));

         }

adjacen_find:搜索给定区间中连续使得_Pred为真的元素位置.

//TEMPLATE FUNCTION adjacent_find WITH PRED

template<class _FwdIt,

         class_Pr> inline

         _FwdIt _Adjacent_find(_FwdIt _First,_FwdIt _Last, _Pr _Pred)

         {       // find first satisfying _Pred with successor

         if(_First != _Last)

                   for(_FwdIt _Firstb; (_Firstb = _First), ++_First != _Last; )

                            if (_Pred(*_Firstb, *_First))

                                     return (_Firstb);

         return(_Last);

         }

 

template<class _FwdIt,

         class_Pr> inline

         _FwdIt adjacent_find(_FwdIt _First,_FwdIt _Last, _Pr _Pred)

         {       // find first satisfying _Pred with successor

         _DEBUG_RANGE(_First, _Last);

         _DEBUG_POINTER(_Pred);

         return(_Rechecked(_First,

                   _Adjacent_find(_Unchecked(_First),_Unchecked(_Last), _Pred)));

         }

照样还是举例说明吧!

举例:

template<typenameT>

bool equal_three( T _value1,T _value2 )

{

         return_value1 == ++ _value2;

}

int main()

{

         vector<int>vecInt;

         vecInt.push_back( 5 );

         vecInt.push_back( 2 );

         vecInt.push_back( 3 );

         vecInt.push_back( 2 );

         vecInt.push_back( 9 );

         vecInt.push_back( 9 );

         vecInt.push_back( 5 );

         vecInt.push_back( 4 );

         vecInt.push_back( 3 );

 

         vector<int>::iteratoriterFind = adjacent_find( vecInt.begin(),vecInt.end() );

         if (iterFind != vecInt.end() )

         {

                   cout<<*(--iterFind)<<"\n";

         }

         iterFind = adjacent_find(vecInt.begin(),vecInt.end(),equal_three<int>);

         if (iterFind != vecInt.end() )

         {

                   cout<<distance(vecInt.begin(),iterFind ) + 1<<"\n";

         }

         system( "pause");

         return0;

}

程序输出:

2

3

需要注意的是前一个2是vecInt的第3个元素.仿函数那个例子需要注意是*_First== ++ *_First来比较