11.2.1 find_first_of函数

find_first_of的参数：
这个算法带有两对迭代器参数来标记两段元素范围，
在第一个范围内查找与第二段范围中任意元素匹配的元素，然后返回一个迭代器，指向第一个匹配的元素。

如果找不到匹配的元素，则返回第一个范围内的end迭代器。

[root@localhost testc++]# vi find_first_of.cpp
1 #include <iostream>
2 #include <algorithm>
3 #include <numeric>
4 #include <list>
5 #include <string>
6 using namespace std;
7
8 int main()
9 {
10     // program for illustration purposes only:
11     // there are much faster ways to solve this problem
12     size_t cnt = 0;
13     string sval;
14     list<string> roster1;
15     list<string> roster2;
16     cout << "Enter roster1 : " << endl;
17     while( cin >> sval)
18         roster1.push_back(sval);
19     cin.clear();//能够进行两个cin输入
20     cout << "Enter roster2 : " << endl;
21     while( cin >> sval)
22         roster2.push_back(sval);
23     list<string>::iterator it = roster1.begin();
24     // look in roster1 for any name also in roster2
25     while ((it = find_first_of(it,roster1.end(),
26                  roster2.begin(),roster2.end()))
27                        != roster1.end()) {
28          ++cnt;
29          // we got a match ,increment it to look in the rest of roster1
30          ++it;
31      }
32      cout << "Found " << cnt
33           << " names on both roster2" << endl;
34      return 0;
35 }
[root@localhost testc++]# g++ find_first_of.cpp
[root@localhost testc++]# ./a.out
Enter roster1 :
aa
bb
Enter roster2 :
bb
cc
Found 1 names on both roster2
[root@localhost testc++]#