首先,这段代码编译得很好：

#include <vector>

typedef struct{
    int x1,x2,x3,x4;
}  ints;

typedef std::vector<ints> vec;

int main(){
    vec v;
    ints a = {0,1,2,3};
    v.push_back(a);
}

以下代码几乎相同：

#include <vector>

typedef std::vector<int[4]> vec;

int main(){
    vec v;
    int a[4] = {0,3};
    v.push_back(a);
}

但它会抛出我将在最后包含的极长的错误输出.为什么编译器对这两个程序的处理方式如此不同？这绝对不直观.

这是我的系统上使用g编译时抛出的编译器错误：

[mattg@pigott Test]$g++ test2.cpp -o test2
In file included from /usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/i586-redhat-linux/bits/c++allocator.h:34,from /usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/allocator.h:48,from /usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/vector:62,from test2.cpp:2:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Tp*,const _Tp&) [with _Tp = int [4]]’:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/stl_vector.h:737:   instantiated from ‘void std::vector<_Tp,_Alloc>::push_back(const _Tp&) [with _Tp = int [4],_Alloc = std::allocator<int [4]>]’
test2.cpp:9:   instantiated from here
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/ext/new_allocator.h:105: error: ISO C++ forbids initialization in array new
In file included from /usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/vector:69,from test2.cpp:2:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc: In member function ‘void std::vector<_Tp,_Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp,_Alloc>::_Tp_alloc_type::pointer,std::vector<_Tp,_Alloc> >,const _Tp&) [with _Tp = int [4],_Alloc = std::allocator<int [4]>]’:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/stl_vector.h:741:   instantiated from ‘void std::vector<_Tp,_Alloc = std::allocator<int [4]>]’
test2.cpp:9:   instantiated from here
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:306: error: array must be initialized with a brace-enclosed initializer
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/stl_vector.h:741:   instantiated from ‘void std::vector<_Tp,_Alloc = std::allocator<int [4]>]’
test2.cpp:9:   instantiated from here
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:312: error: invalid array assignment
In file included from /usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/i586-redhat-linux/bits/c++allocator.h:34,from test2.cpp:2:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::destroy(_Tp*) [with _Tp = int [4]]’:
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/vector.tcc:353:   instantiated from ‘void std::vector<_Tp,_Alloc = std::allocator<int [4]>]’
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/stl_vector.h:741:   instantiated from ‘void std::vector<_Tp,_Alloc = std::allocator<int [4]>]’
test2.cpp:9:   instantiated from here
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/ext/new_allocator.h:115: error: request for member ‘~int [4]’ in ‘* __p’,which is of non-class type ‘int [4]’