equal和mismatch算法的功能是比较容器中的两个区间内的元素。这两个算法各有3个参数first1,last1和first2.如果对于区间[first1,last1)内所有的first1+i,first1+i和first2所在位置处的元素都相等，则equal算法返回真，否则返回假。mismatch算法的返回值是由两个迭代器first1+i和first2+i组成的一个pair,表示第1对不相等的元素的位置。如果没有找到不相等的元素，则返回last1和first2+(last1-first1)。因此，语句
equal(first1,last1,first2)和mismatch(first1,last1,first2).first==last1是等价的
1 // Illustrating the generic equal and mismatch algorithms
2 #include <iostream>
3 #include <cassert>
4 #include <algorithm>
5 #include <string>
6 #include <list>
7 #include <deque>
8 #include <vector>
9 using namespace std;
10
11 int main()
12 {
13 cout << "Illustrating the generic equal "
14 << "and mismatch algorithms." << endl;
15 list<string> driver_list;
16 vector<string> vec;
17 deque<string> deq;
18
19 driver_list.insert(driver_list.end(), "Clark");
20 driver_list.insert(driver_list.end(), "Rindt");
21 driver_list.insert(driver_list.end(), "Senna");
22
23 vec.insert(vec.end(), "Clark");
24 vec.insert(vec.end(), "Rindt");
25 vec.insert(vec.end(), "Senna");
26 vec.insert(vec.end(), "Berger");
27
28 deq.insert(deq.end(), "Clark");
29 deq.insert(deq.end(), "Berger");
30
31 // Show that driver_list and the first 3 elements of
32 // vec are equal in all corresponding positions:
33 assert (equal(driver_list.begin(), driver_list.end(),
34 vec.begin()));
35
36 // Show that deq and the first 2 elements of driver_list
37 // are not equal in all corresponding positions:
38 assert (!equal(deq.begin(), deq.end(),
39 driver_list.begin()));
40
41 // Find the corresponding positions in deq and driver_list
42 // at which unequal elements first occur:
43 pair<deque<string>::iterator, list<string>::iterator>
44 pair1 = mismatch(deq.begin(), deq.end(),
45 driver_list.begin());
46
47 if (pair1.first != deq.end())
48 cout << "First disagreement in deq and driver_list:\n "
49 << *(pair1.first) << " and " << *(pair1.second)
50 << endl;
51 return 0;
52 }
