这个为什么会报错?(关于vector的问题)
#include <iostream>#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;
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;
return 0;
}