c – 模板化封闭的模板化结构的初始化列表
作者:互联网
#include <array>
#include <vector>
#include <cinttypes>
#include <iostream>
using namespace std;
template<size_t N>
struct item_t {
array<uint32_t, N> weight = {0};
};
int main(void) {
vector<item_t<3>> items;
items.emplace_back({{9,2,3}});
cout << items[0].weight[0] << endl;
return 0;
};
我在这里有点不知所措.错误在emplace_back行上,不知道如何解决它.任何帮助或提示将不胜感激,谢谢.
编辑
gcc版本4.8.2
$g++ -std=c++11 test.cpp
test.cpp: In function ‘int main()’:
test.cpp:16:30: error: no matching function for call to ‘std::vector<item_t<3ul> >::emplace_back(<brace-enclosed initializer list>)’
items.emplace_back({{9,2,3}});
^
test.cpp:16:30: note: candidate is:
In file included from /usr/include/c++/4.8/vector:69:0,
from test.cpp:2:
/usr/include/c++/4.8/bits/vector.tcc:91:7: note: void std::vector<_Tp, _Alloc>::emplace_back(_Args&& ...) [with _Args = {}; _Tp = item_t<3ul>; _Alloc = std::allocator<item_t<3ul> >]
vector<_Tp, _Alloc>::
^
/usr/include/c++/4.8/bits/vector.tcc:91:7: note: candidate expects 0 arguments, 1 provided
问题在于struct initialization = {0}和emplace_back.
解决方法:
emplace_back()使用模板参数推导来确定传递给函数的元素的类型.括号括起初始化列表不是表达式,也没有类型,因此模板无法推断.你必须在这里显式调用构造函数:
items.emplace_back(item_t<3>{{1,2,3}});
标签:list-initialization,c,c11,templates,struct 来源: https://codeday.me/bug/20190728/1562074.html