三种定义数组的方式：分别是C语言的定义方式、STL vector和C++11的array对象。

附源代码：

#include <iostream>
#include <vector> // STL C++98
#include <array> // C++11
int main()
{
 using namespace std;
// C, original C++
 double a1[4] = {1.2, 2.4, 3.6, 4.8};
// C++98 STL
 vector<double> a2(4); // create vector with 4 elements
// no simple way to initialize in C98
 a2[0] = 1.0/3.0;
 a2[1] = 1.0/5.0;
 a2[2] = 1.0/7.0;
 a2[3] = 1.0/9.0;
// C++11 -- create and initialize array object
 array<double, 4> a3 = {3.14, 2.72, 1.62, 1.41}; 
 array<double, 4> a4;
 a4 = a3; // valid for array objects of same size
// use array notation
 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[2] << endl;
 cout << "a4[2]: " << a4[2] << " at " << &a4[2] << endl;
// misdeed
 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;
 cin.get();
 return 0;
}

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