樓主用的是支援c++11的編譯器吧，

C++11新增了模板類array
{}初始化的方法，僅被最新的C++11標準支持，有個專門的術語：initializer-list

在不支援c++11的編譯器上會報錯， 例如在我的機器上報錯如下：

   #include <array>
   #include <iostream>
   using namespace std;
   
   int main()
   {
       array<int, 3> a;
       a = {0, 1, 2}; 
       cout<<a[1]<<endl;
       return 0;
   }

In file included from /usr/include/c++/4.9/array:35:0,

from huakuohao.cpp:1:
/usr/include/c++/4.9/bits/c++0x_warning.h:32:2: error: #error This file requires     
compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
 #error This file requires compiler and library support for the \
  ^
huakuohao.cpp: In function ‘int main()’:
huakuohao.cpp:7:5: error: ‘array’ was not declared in this scope
huakuohao.cpp:8:17: warning: extended initializer lists only available with -std=c++11 or -std=gnu++11