这个为什么会报错？(关于vector的问题)

arrary没有定义类型，
vector<double> arrary(4)这样写会不会更好一点

你把改完的代码贴上来看一下

1.a2没有申明
2.vector对象不能通过下标来添加元素必须要用push_back()

using namespace std;

int main()
{
    double a1[4] = {1.2, 2.4, 3.6, 4.8};
    double tmp[4] = {3.0 ,1.5 ,7.0 ,9.0};
    vector<double> a4(4);
    std::vector<double> a2;

    for (size_t index = 0 ; index <4; ++index){
        a2.push_back(1.0 /tmp[index]);
    }

/*
    a2[0] = 1.0/3.0;
    a2[1] = 1.0/1.5;
    a2[2] = 1.0/7.0;
    a2[3] = 1.0/9.0;
    */
    vector<double> a3 = {3.14, 2.72, 1.62, 1.41};
    a4 = a3;
    cout << "a1[2]" << a1[2]<<"at " << &a1[2] << endl;
    /*cout << "a1[2]：" << a1[2] << " at " << a1[2] << endl;
    cout << "a2[2]：" << a2[2] << " at " << &a2[2] << endl;
    cout << "a3[2]：" << a3[2] << " at " << &a3[3] << endl;
    cout << "a4[2]：" << a4[2] << " at " << &a4[4] << endl;
    a1[-2] = 20.2;
    cout << "a1[-2]： " << a1[-2] << " at " << &a1[-2] << endl;
    cout << "a3[2]：" << a3[2] << " at " << &a3[2] << endl;
    cout << "a4[2]：" << a4[2] << " at " << &a4[2] << endl;
    */
    return 0;
}

[此贴子已经被作者于2018-7-19 17:14编辑过]

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

int main()
{
    double a1[4] = { 1.2, 2.4, 3.6, 4.8 };
   
    vector<double> a2(4);
    a2[0] = 1.0/3.0;
    a2[1] = 1.0/1.5;
    a2[2] = 1.0/7.0;
    a2[3] = 1.0/9.0;
   
    array<double,4> a3 = { 3.14, 2.72, 1.62, 1.41 };
    array<double,4> a4 = a3;
   
    cout << "a1[2]：" << a1[2] << " at " << &a1[2] << endl;
    cout << "a2[2]：" << a2[2] << " at " << &a2[2] << endl;
    cout << "a3[2]：" << a3[2] << " at " << &a3[3] << endl;
    cout << "a4[2]：" << a4[2] << " at " << &a4[4] << endl;
   
    a1[2] = 20.2;
    cout << "a1[2]：" << a1[2] << " at " << &a1[2] << endl;
    cout << "a3[2]：" << a3[2] << " at " << &a3[2] << endl;
    cout << "a4[2]：" << a4[2] << " at " << &a4[2] << endl;
}