copy() algorithm是很好用的algorithm，但偏偏就是沒有copy_if()，但透過remove_copy_if()則可達到相同的要求。
remove_copy_if()的思考方式和copy_if()相反，若UnaryPredicate為true，則不copy，若為false，則copy。
此範例demo若為remove_copy_if() algorithm，先輸出奇數，再輸出偶數。
1
/*
2
(C) OOMusou 2006 http://oomusou.cnblogs.com
3
4Filename : GenericAlgo_remove_copy_if.cpp
5Compiler : Visual C++ 8.0 / ISO C++
6Description : Demo how to use remove_copy_if() algorithm
7Release : 11/12/2006 1.0
8
*/
9
10#include <iostream>
11#include <algorithm>
12#include <vector>
13
14using namespace std;
15
16bool isOdd(int);
17bool isEven(int);
18
19int main() {
20 vector<int> ivec;
21 copy(istream_iterator<int>(cin), istream_iterator<int>(), back_inserter(ivec));
22
23 remove_copy_if(ivec.begin(), ivec.end(), ostream_iterator<int>(cout, " "), isEven);
24 cout << endl;
25 remove_copy_if(ivec.begin(), ivec.end(), ostream_iterator<int>(cout," "), isOdd);
26
27 return 0;
28}
29
30bool isOdd(int val) {
31 return val%2;
32}
33
34bool isEven(int val) {
35 return !(val%2);
36}
/* 
2
(C) OOMusou 2006 http://oomusou.cnblogs.com3
4
Filename : GenericAlgo_remove_copy_if.cpp5
Compiler : Visual C++ 8.0 / ISO C++6
Description : Demo how to use remove_copy_if() algorithm7
Release : 11/12/2006 1.08
*/9
10
#include <iostream>11
#include <algorithm>12
#include <vector>13
14
using namespace std;15
16
bool isOdd(int);17
bool isEven(int);18
19
int main() {
20
vector<int> ivec;21
copy(istream_iterator<int>(cin), istream_iterator<int>(), back_inserter(ivec));22
23
remove_copy_if(ivec.begin(), ivec.end(), ostream_iterator<int>(cout, " "), isEven);24
cout << endl;25
remove_copy_if(ivec.begin(), ivec.end(), ostream_iterator<int>(cout," "), isOdd);26
27
return 0;28
}29
30
bool isOdd(int val) {31
return val%2;32
}33
34
bool isEven(int val) {35
return !(val%2);36
}
執行結果
11 2 3 4 5 6
2^Z
31 3 5
42 4 6 請按任意鍵繼續 . . .
1 2 3 4 5 62
^Z3
1 3 54
2 4 6 請按任意鍵繼續 . . .