我不清楚以下内容。
首先,这段代码可以正常编译:
#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] = {0,1,2,3};
v.push_back(a);
}
但它会抛出我将在最后包含的超长错误输出。为什么编译器对待这两个程序如此不同?这绝对不直观。
这是在我使用 g++ 编译的系统上抛出的编译器错误:
[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>::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/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>::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/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 /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>::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>::_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>::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:115: error: request for member ‘~int [4]’ in ‘* __p’, which is of non-class type ‘int [4]’
最佳答案
error: ISO C++ forbids initialization in array new
error: array must be initialized with a brace-enclosed initializer
error: invalid array assignment
error: request for member ‘~int [4]’ in ‘* __p’, which is of non-class type ‘int [4]’
要理解其中一个错误,请想象以下情况:
void main() {
int a[4] = {0,1,2,3};
int b[4] = a;
}
相对于:
typedef struct{
int x1,x2,x3,x4;
} ints;
int main()
{
ints a;
ints b = a;
}
甚至:
typedef struct{
int x[4];
} ints;
int main()
{
ints a;
ints b = a;
}
无法通过赋值运算符复制 C/C++ 数组,但可以复制包含数组的 struct
。
所以一个简单的解决方法是:
typedef struct{
int x[4];
} ints;
typedef std::vector<ints> vec;
int main(){
vec v;
ints a = { {0,1,2,3} };
v.push_back(a);
}
关于c++ - 关于在 C++ 中将数组存储在 std::vector 中的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/1468058/