c++ - vector 比较失败

Question

我正在尝试比较两个 vector ，据我所知， vector 支持关系运算符并且它以这种方式工作:将 v1 中的第一个元素与 v2 中的第一个元素进行比较，依此类推......

为什么以下代码的结果是 (true) where the last element in v1 > v2 ?!

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

void main()
{

    vector <int> V1 = { 2,1,0,3 };
    vector <int> V2 = { 3,4,2,2 };

    cout << (V1 <= V2);  //print true !!


    system("pause");
}

Answer 1

operator==,!=,<,<=,>,>=比较两个 vector lexicographicall 的内容。来自 http://en.cppreference.com/w/cpp/algorithm/lexicographical_compare :

Lexicographical comparison is a operation with the following properties:

• Two ranges are compared element by element.
• The first mismatching element defines which range is lexicographically less or greater than the other.

这就是为什么字符串“abcdx”小于“abced”和[2,1,0, 3] 小于 [3,4,2,2]。