C++大学教程（第七版）Chapter22.5标准模板库-算法：Fig22_27.cpp

后面的几篇博客会讲STL的算法,本文主要讲：

        equal()函数用来比较两个序列的值是否相同？如果两个序列的长度不同，则equal（）返回false。==运算符用于进行比较操作。还有另外一个版本的equal，使用一个二元谓词函数作为第四个参数，估计是比较复杂，本例子并没有包含这个版本的equal（）。

        mismatch（）函数比较两个序列的值并返回一个pair对象，pair中的两个迭代器表明两个序列中不匹配的元素所在的位置。

        lexicographical_compare（）函数会检测第一个序列中的元素是否比第二个序列中的小？如果小，就返回true，如果大或者相等，就返回false。

代码如下：

// Fig22_27_STL_Algor_equal_mismatch_lexicographical_compare.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//Standard library functions equal, mismatch and lexicographical_compare

#include <iostream>
#include <algorithm>
#include <vector>
#include <iterator>
using namespace std;

int main()
{
   // std::cout << "Hello World!\n";
	const int SIZE = 10;
	int a1[SIZE] = {1,2,3,4,5,6,7,8,9,10};
	int a2[SIZE] = { 1,2,3,4,1000,6,7,8,9,10 };
	vector <int> v1(a1,a1 + SIZE);//copy of a1,通过数组地址初始化vector
	vector <int> v2(a1,a1 + SIZE);//copy of a1,通过数组地址初始化vector
	vector <int> v3(a2,a2 + SIZE);//copy of a2,通过数组地址初始化vector
	ostream_iterator<int> output(cout," ");

	cout << "Vector V1 contains: ";
	copy(v1.begin(),v1.end(),output);
	//cout <<"V1.capacity() is:"<< v1.capacity() << endl;

	cout << "\nVector V2 contains: ";
	copy(v2.begin(), v2.end(), output);

	cout << "\nVector V3 contains: ";
	copy(v3.begin(), v3.end(), output);
	//compare vectors v1 and v2 for equality
	bool result = std::equal(v1.begin(),v1.end(),v2.begin());
	cout << "\n\n Vector v1  " << (result ? "is" : "is not") << " equal to vector v2.\n";

	//compare vectors v1 and v3 for equality
	bool result2 = std::equal(v1.begin(), v1.end(), v3.begin());
	cout << "\n\n Vector v1  " << (result2 ? "is" : "is not") << " equal to vector v3.\n";

	//location represents pair of vector iterators
	pair <vector<int>::iterator, vector<int>::iterator> location;
	//check for mismatch between v1 and v3
	location = std::mismatch(v1.begin(),v1.end(),v3.begin());
	cout << "\nThere is a mismatch between v1 and v3 at location " << (location.first - v1.begin()) << "\nWhere v1 contains " << *location.first << " and v3 contains " << *location.second << "\n\n";

	char c1[SIZE] = "HELLO";
	char c2[SIZE] = "BYE BYE";

	//perform lexicographical comparision of c1 and c2
	bool result3 = lexicographical_compare(c1,c1+SIZE,c2,c2+SIZE);
	cout << c1 << (result3 ? " is less than " : " is greater than or equal to ") << c2 << endl;
}//end of main

运行结果：

Vector V1 contains: 1 2 3 4 5 6 7 8 9 10
Vector V2 contains: 1 2 3 4 5 6 7 8 9 10
Vector V3 contains: 1 2 3 4 1000 6 7 8 9 10

 Vector v1  is equal to vector v2.


 Vector v1  is not equal to vector v3.

There is a mismatch between v1 and v3 at location 4
Where v1 contains 5 and v3 contains 1000

HELLO is greater than or equal to BYE BYE

这个程序就是比较初级，需要进一步研究的需要再仔细研究研究了。