使用initializer_list初始化数组

Initializing an array with a initializer_list?

本文关键字：初始化 数组 list initializer 使用      更新时间：2023-10-16

这可能吗？

#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 };
}

但这导致了这个错误：

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>&&’

在这种情况下不是。您可以使用列表初始化器初始化array

std::array<int, 2> a{1,2};

但是不能用initializer_list初始化array，因为array只是一个只有默认构造函数和复制构造函数的聚合类型。

您可以将数组留空，然后将initializer_list的内容复制到其中。

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