我正在尝试使用以下代码生成大小为 10 的随机 unordered_multimap
:
#include <algorithm>
#include <unordered_map>
#include <cstdlib>
int main()
{
auto m = std::unordered_multimap<int, int>(10);
std::generate(
m.begin(),
m.end(),
[](){return std::pair{std::rand(),std::rand()};}
);
}
但是编译不会报错
In file included from /usr/include/c++/7/algorithm:62:0,
from main.cpp:2:
/usr/include/c++/7/bits/stl_algo.h: In instantiation of ‘void std::generate(_FIter, _FIter, _Generator) [with _FIter = std::__detail::_Node_iterator<std::pair<const int, int>, false, false>; _Generator = main()::<lambda()>]’:
<span class="error_line" onclick="ide.gotoLine('main.cpp',11)">main.cpp:11:5</span>: required from here
/usr/include/c++/7/bits/stl_algo.h:4438:11: error: use of deleted function ‘std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(typename std::conditional, std::is_copy_assignable<_T2> > >::value, const std::pair<_T1, _T2>&, const std::__nonesuch_no_braces&>::type) [with _T1 = const int; _T2 = int; typename std::conditional, std::is_copy_assignable<_T2> > >::value, const std::pair<_T1, _T2>&, const std::__nonesuch_no_braces&>::type = const std::pair&]’
*__first = __gen();
~~~~~~~~~^~~~~~~~~
In file included from /usr/include/c++/7/utility:70:0,
from /usr/include/c++/7/unordered_map:38,
from main.cpp:1:
/usr/include/c++/7/bits/stl_pair.h:378:7: note: declared here
operator=(typename conditional<
^~~~~~~~
问:是否可以使用std::generate
生成随机unordered_multimap
?如果不是,最好的方法是什么?
PS:我知道我应该使用 std::default_random_engine
而不是 std::rand
,我在真实代码中这样做,这只是为了演示目的.
最佳答案
您可以使用 std::insert_iterator
类模板来实现你正在寻找的东西:
auto m = std::unordered_multimap<int, int>{};
std::generate_n(std::insert_iterator(m, m.begin()),
10, [](){ return std::pair{std::rand(),std::rand()}; });
关于c++ - 使用 std::generate 的随机 unordered_multimap,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54441262/