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++]#