example_13_5.cpp

data+structures+using+c的源码

//Function Objects

#include <iostream>
#include <string>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <vector>
#include <functional>

using namespace std;

int funcAdd(plus<int>, int, int);

int main()
{
   plus<int> addNum;                                 //Line 1
   int num = addNum(34, 56);                         //Line 2

   cout<<"Line 3: num = "<<num<<endl;                //Line 3

   plus<string> joinString;                          //Line 4

   string str1 = "Hello ";                           //Line 5
   string str2 = "There";                            //Line 6

   string str = joinString(str1, str2);              //Line 7
 
   cout<<"Line 8: str = "<<str<<endl;                //Line 8

   cout<<"Line 9: Sum of 34 and 26 = "
       <<funcAdd(addNum, 34, 26)<<endl;              //Line 9


   int list[8] = {1, 2, 3, 4, 5, 6, 7, 8};           //Line 10

   vector<int> intList(list, list + 8);              //Line 11
   ostream_iterator<int> screenOut(cout, " ");       //Line 12

   cout<<"Line 13: intList: ";                       //Line 13
   copy(intList.begin(), intList.end(), screenOut);  //Line 14
   cout<<endl;                                       //Line 15

        //accumulate
   int sum = accumulate(intList.begin(), 
                        intList.end(), 0);           //Line 16

   cout<<"Line 17: Sum of the elements of intList = "
       <<sum<<endl;                                   //Line 17

   int product = accumulate(intList.begin(), 
                            intList.end(), 
                            1, multiplies<int>());   //Line 18

   cout<<"Line 19: Product of the elements of intList = "
       <<product<<endl;                              //Line 19

   return 0;
}

int funcAdd(plus<int> sum, int x, int y)
{
    return sum(x,y);
}