functional filter()

 1 #include "pch.h"
 2 #include <iostream>
 3 #include <deque>
 4 #include <string>
 5 #include <list>
 6 #include <algorithm>
 7 #include <vector>
 8 #include <functional>
 9 using namespace std;
10 
11 template<typename inputiterator, typename outputiterator,typename elemtype, typename comp>
12 outputiterator
13 filter(inputiterator first, inputiterator last, 
　　　　　　outputiterator at, const elemtype &val, comp pred)
14 {
15     while((first=find_if(first, last, bind2nd(pred, val)))!=last)
16     {
17         cout << "found value:" << *first << endl;
18         *at++ = *first++;
19     }
20     return at;
21 }
22 
23 int main()
24 {
25     const int elem_size = 8;
26     int ia[elem_size] = { 12,8,43,0,6,21,3,7 };
27     vector<int> ivec(ia,ia+elem_size);
28     int ia2[elem_size];
29     vector<int> ivec2(elem_size);
30     cout << "filtering integer array for values less than 8\n";
31     filter(ia, ia + elem_size, ia2, elem_size, less<int>());
32     cout << "filtering integer vector for values greater than 8\n";
33     filter(ivec.begin(), ivec.end(), ivec2.begin(), elem_size, greater<int>());
34     return 0;
35 }