11
是否有可能?用initializer_list初始化一个数组?
#include <array>
#include <initializer_list>
struct A
{
A (std::initializer_list<int> l)
: m_a (l)
{
}
std::array<int,2> m_a;
};
int main()
{
A a{ 1,2 };
}
但这会导致这个错误:
t.cpp: In constructor ‘A::A(std::initializer_list<int>)’:
t.cpp:7:19: error: no matching function for call to ‘std::array<int, 2ul>::array(std::initializer_list<int>&)’
: m_a (l)
^
t.cpp:7:19: note: candidates are:
In file included from t.cpp:1:0:
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: std::array<int, 2ul>::array()
struct array
^
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: candidate expects 0 arguments, 1 provided
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: constexpr std::array<int, 2ul>::array(const std::array<int, 2ul>&)
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: no known conversion for argument 1 from ‘std::initializer_list<int>’ to ‘const std::array<int, 2ul>&’
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: constexpr std::array<int, 2ul>::array(std::array<int, 2ul>&&)
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4/array:81:12: note: no known conversion for argument 1 from ‘std::initializer_list<int>’ to ‘std::array<int, 2ul>&&’
这是不可能的,作为一种解决方法,手动复制'initializer_list'的元素:'A(std :: initializer_list l)/ *不要初始化m_a */{std :: copy(l。 begin(),l.end(),m_a.begin());}' –
Mankarse
2015-03-19 11:38:50
请注意,这不是特殊的构造函数; 'std :: initializer_list x = {1,2}; std :: array m {?????? };'。您只能将这些东西放在聚合初始化的一部分,即每个元素的初始化符一个接一个。 –
2015-03-19 11:49:34
请参阅http://stackoverflow.com/q/5549524/1436796,它也提供了一种可能的解决方案,即使成员数组应该被限定为'const'(这会使得它不为空,然后再复制列表内容)。 – 2015-03-19 12:37:56