a.h
 1 template <class T>
 2 void printInterval(T first,T last)
 3 {
 4     for (;first!=last;first++)
 5         cout<<*first<<" ";
 6 }
 7 
 8 
 9 int sumSquares(int total,int value)
10 {
11     return total+value*value;
12 }
13 
14 
15 template<typename T>
16 class sumPowers
17 {
18 private:
19     int power;
20 public:
21     sumPowers(int p):power(p){}
22     const T operator()(const T& total,const T& value)
23     {
24         T v = value;
25         for (int i=0;i<power-1;i++)
26             v = v*value;
27         return total+v;
28     }
29 };
View Code
test.cpp
 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <functional>
 5 #include <numeric>
 6 #include "a.h"
 7 
 8 #define SIZE 10
 9 
10 using namespace std;
11 
12 int main()
13 {
14 
15     int a[SIZE]={1,2,3,4,5,6,7,8,9,10};
16     vector<int> v(a,a+SIZE);
17     cout<<"1) ";printInterval(v.begin(),v.end());cout<<endl;
18 
19     int result = -1;
20 
21     result = accumulate(v.begin(),v.end(),0);
22     cout<<"2)累加和: "<<result<<endl;
23 
24     result = accumulate(v.begin(),v.end(),0,sumSquares);
25     cout<<"3)平方和："<<result<<endl;
26 
27     result = accumulate(v.begin(),v.end(),0,sumPowers<int>(3));
28     cout<<"4)立方和： "<<result<<endl;
29 
30     getchar();
31     return 0;
32 }
View Code

 numeric

 1 template<class _InIt,
 2     class _Ty> inline
 3     _Ty _Accumulate(_InIt _First, _InIt _Last, _Ty _Val)
 4     {    // return sum of _Val and all in [_First, _Last)
 5     for (; _First != _Last; ++_First)
 6         _Val = (_Ty)(_Val + *_First);
 7     return (_Val);
 8     }
 9 
10 template<class _InIt,
11     class _Ty> inline
12     _Ty accumulate(_InIt _First, _InIt _Last, _Ty _Val)
13     {    // return sum of _Val and all in [_First, _Last)
14     _DEBUG_RANGE(_First, _Last);
15     return (_Accumulate(_Unchecked(_First), _Unchecked(_Last), _Val));
16     }
View Code
 1 template<class _InIt,
 2     class _Ty,
 3     class _Fn2> inline
 4     _Ty _Accumulate(_InIt _First, _InIt _Last, _Ty _Val, _Fn2 _Func)
 5     {    // return sum of _Val and all in [_First, _Last), using _Func
 6     for (; _First != _Last; ++_First)
 7         _Val = _Func(_Val, *_First);
 8     return (_Val);
 9     }
10 
11 template<class _InIt,
12     class _Ty,
13     class _Fn2> inline
14     _Ty accumulate(_InIt _First, _InIt _Last, _Ty _Val, _Fn2 _Func)
15     {    // return sum of _Val and all in [_First, _Last), using _Func
16     _DEBUG_RANGE(_First, _Last);
17     _DEBUG_POINTER(_Func);
18     return (_Accumulate(_Unchecked(_First), _Unchecked(_Last), _Val, _Func));
19     }
View Code

若一个类重载了运算符“（）”，则该类的对象就称为函数对象。