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这是我的 previous one 的后续问题关于 boost::spirit::x3
和 boost::string_view
.
虽然我可以解析成 std::vector<std::string>
( live example ),解析为 std::vector<boost::string_view>
失败并出现以下编译错误:
#include <iostream>
#include <string>
#include <boost/utility/string_view.hpp>
namespace boost {
namespace spirit { namespace x3 { namespace traits {
template <typename It>
void move_to(It b, It e, boost::string_view& v)
{
v = boost::string_view(b, std::size_t(std::distance(b,e)));
}
} } }
} // namespace boost
#include <boost/spirit/home/x3.hpp>
namespace parser
{
namespace x3 = boost::spirit::x3;
using x3::char_;
using x3::raw;
const auto str_vec = *(raw[ +~char_('_')] >> '_');
}
int main()
{
std::string input = "hello_world_";
std::vector<boost::string_view> strVec;
parse(input.data(), input.data()+input.size(), parser::str_vec, strVec);
for(auto& x : strVec) { std::cout << x << std::endl; }
}
In file included from /usr/local/include/c++/6.1.0/bits/stl_tempbuf.h:60:0,
from /usr/local/include/c++/6.1.0/bits/stl_algo.h:62,
from /usr/local/include/c++/6.1.0/algorithm:62,
from /usr/local/include/boost/utility/string_view.hpp:27,
from main.cpp:4:
/usr/local/include/c++/6.1.0/bits/stl_construct.h: In instantiation of 'void std::_Construct(_T1*, _Args&& ...) [with _T1 = boost::basic_string_view<char, std::char_traits<char> >; _Args = {const char&}]':
/usr/local/include/c++/6.1.0/bits/stl_uninitialized.h:75:18: required from 'static _ForwardIterator std::__uninitialized_copy<_TrivialValueTypes>::__uninit_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = const char*; _ForwardIterator = boost::basic_string_view<char, std::char_traits<char> >*; bool _TrivialValueTypes = false]'
/usr/local/include/c++/6.1.0/bits/stl_uninitialized.h:126:15: required from '_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = const char*; _ForwardIterator = boost::basic_string_view<char, std::char_traits<char> >*]'
/usr/local/include/c++/6.1.0/bits/stl_uninitialized.h:281:37: required from '_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>&) [with _InputIterator = const char*; _ForwardIterator = boost::basic_string_view<char, std::char_traits<char> >*; _Tp = boost::basic_string_view<char, std::char_traits<char> >]'
/usr/local/include/c++/6.1.0/bits/stl_vector.h:1288:33: required from 'void std::vector<_Tp, _Alloc>::_M_range_initialize(_ForwardIterator, _ForwardIterator, std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = boost::basic_string_view<char, std::char_traits<char> >; _Alloc = std::allocator<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/c++/6.1.0/bits/stl_vector.h:1261:4: required from 'void std::vector<_Tp, _Alloc>::_M_initialize_dispatch(_InputIterator, _InputIterator, std::__false_type) [with _InputIterator = const char*; _Tp = boost::basic_string_view<char, std::char_traits<char> >; _Alloc = std::allocator<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/c++/6.1.0/bits/stl_vector.h:406:11: [ skipping 9 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/local/include/boost/spirit/home/x3/operator/detail/sequence.hpp:496:24: required from 'static bool boost::spirit::x3::detail::parse_into_container_impl<boost::spirit::x3::sequence<L, R>, Context, RContext>::call(const parser_type&, Iterator&, const Iterator&, const Context&, RContext&, Attribute&) [with Iterator = const char*; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >; Left = boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >; Right = boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type>; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; boost::spirit::x3::detail::parse_into_container_impl<boost::spirit::x3::sequence<L, R>, Context, RContext>::parser_type = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >]'
/usr/local/include/boost/spirit/home/x3/core/detail/parse_into_container.hpp:287:74: required from 'bool boost::spirit::x3::detail::parse_into_container(const Parser&, Iterator&, const Iterator&, const Context&, RContext&, Attribute&) [with Parser = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >; Iterator = const char*; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/boost/spirit/home/x3/operator/kleene.hpp:32:48: required from 'bool boost::spirit::x3::kleene<Subject>::parse(Iterator&, const Iterator&, const Context&, RContext&, Attribute&) const [with Iterator = const char*; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >; Subject = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >]'
/usr/local/include/boost/spirit/home/x3/core/parse.hpp:35:68: required from 'bool boost::spirit::x3::parse_main(Iterator&, Iterator, const Parser&, Attribute&) [with Iterator = const char*; Parser = boost::spirit::x3::kleene<boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> > >; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/boost/spirit/home/x3/core/parse.hpp:60:26: required from 'bool boost::spirit::x3::parse(const Iterator&, Iterator, const Parser&, Attribute&) [with Iterator = const char*; Parser = boost::spirit::x3::kleene<boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> > >; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
main.cpp:36:75: required from here
/usr/local/include/c++/6.1.0/bits/stl_construct.h:75:7: error: no matching function for call to 'boost::basic_string_view<char, std::char_traits<char> >::basic_string_view(const char&)'
{ ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
/usr/local/include/boost/utility/string_view.hpp:82:23: note: candidate: constexpr boost::basic_string_view<charT, traits>::basic_string_view(const charT*) [with charT = char; traits = std::char_traits<char>] <near match>
BOOST_CONSTEXPR basic_string_view(const charT* str)
^~~~~~~~~~~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:82:23: note: conversion of argument 1 would be ill-formed:
In file included from /usr/local/include/c++/6.1.0/bits/stl_tempbuf.h:60:0,
from /usr/local/include/c++/6.1.0/bits/stl_algo.h:62,
from /usr/local/include/c++/6.1.0/algorithm:62,
from /usr/local/include/boost/utility/string_view.hpp:27,
from main.cpp:4:
/usr/local/include/c++/6.1.0/bits/stl_construct.h:75:7: error: invalid conversion from 'char' to 'const char*' [-fpermissive]
{ ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
/usr/local/include/boost/utility/string_view.hpp:85:23: note: candidate: constexpr boost::basic_string_view<charT, traits>::basic_string_view(const charT*, boost::basic_string_view<charT, traits>::size_type) [with charT = char; traits = std::char_traits<char>; boost::basic_string_view<charT, traits>::size_type = long unsigned int]
BOOST_CONSTEXPR basic_string_view(const charT* str, size_type len)
^~~~~~~~~~~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:85:23: note: candidate expects 2 arguments, 1 provided
/usr/local/include/boost/utility/string_view.hpp:78:9: note: candidate: template<class Allocator> boost::basic_string_view<charT, traits>::basic_string_view(const std::__cxx11::basic_string<charT, traits, Allocator>&)
basic_string_view(const std::basic_string<charT, traits,
^~~~~~~~~~~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:78:9: note: template argument deduction/substitution failed:
In file included from /usr/local/include/c++/6.1.0/bits/stl_tempbuf.h:60:0,
from /usr/local/include/c++/6.1.0/bits/stl_algo.h:62,
from /usr/local/include/c++/6.1.0/algorithm:62,
from /usr/local/include/boost/utility/string_view.hpp:27,
from main.cpp:4:
/usr/local/include/c++/6.1.0/bits/stl_construct.h:75:7: note: mismatched types 'const std::__cxx11::basic_string<char, std::char_traits<char>, Allocator>' and 'const char'
{ ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from main.cpp:4:0:
/usr/local/include/boost/utility/string_view.hpp:68:23: note: candidate: constexpr boost::basic_string_view<charT, traits>::basic_string_view(const boost::basic_string_view<charT, traits>&) [with charT = char; traits = std::char_traits<char>]
BOOST_CONSTEXPR basic_string_view(const basic_string_view &rhs) BOOST_NOEXCEPT
^~~~~~~~~~~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:68:23: note: no known conversion for argument 1 from 'const char' to 'const boost::basic_string_view<char, std::char_traits<char> >&'
/usr/local/include/boost/utility/string_view.hpp:65:23: note: candidate: constexpr boost::basic_string_view<charT, traits>::basic_string_view() [with charT = char; traits = std::char_traits<char>]
BOOST_CONSTEXPR basic_string_view() BOOST_NOEXCEPT
^~~~~~~~~~~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:65:23: note: candidate expects 0 arguments, 1 provided
In file included from /usr/local/include/c++/6.1.0/bits/char_traits.h:39:0,
from /usr/local/include/c++/6.1.0/ios:40,
from /usr/local/include/c++/6.1.0/ostream:38,
from /usr/local/include/c++/6.1.0/iostream:39,
from main.cpp:1:
/usr/local/include/c++/6.1.0/bits/stl_algobase.h: In instantiation of 'static _OI std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m(_II, _II, _OI) [with _II = const char*; _OI = boost::basic_string_view<char, std::char_traits<char> >*]':
/usr/local/include/c++/6.1.0/bits/stl_algobase.h:386:44: required from '_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = boost::basic_string_view<char, std::char_traits<char> >*]'
/usr/local/include/c++/6.1.0/bits/stl_algobase.h:422:45: required from '_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = const char*; _OI = __gnu_cxx::__normal_iterator<boost::basic_string_view<char, std::char_traits<char> >*, std::vector<boost::basic_string_view<char, std::char_traits<char> > > >]'
/usr/local/include/c++/6.1.0/bits/stl_algobase.h:455:8: required from '_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI = __gnu_cxx::__normal_iterator<boost::basic_string_view<char, std::char_traits<char> >*, std::vector<boost::basic_string_view<char, std::char_traits<char> > > >]'
/usr/local/include/c++/6.1.0/bits/vector.tcc:637:16: required from 'void std::vector<_Tp, _Alloc>::_M_range_insert(std::vector<_Tp, _Alloc>::iterator, _ForwardIterator, _ForwardIterator, std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = boost::basic_string_view<char, std::char_traits<char> >; _Alloc = std::allocator<boost::basic_string_view<char, std::char_traits<char> > >; std::vector<_Tp, _Alloc>::iterator = __gnu_cxx::__normal_iterator<boost::basic_string_view<char, std::char_traits<char> >*, std::vector<boost::basic_string_view<char, std::char_traits<char> > > >; typename std::_Vector_base<_Tp, _Alloc>::pointer = boost::basic_string_view<char, std::char_traits<char> >*]'
/usr/local/include/c++/6.1.0/bits/stl_vector.h:1375:4: required from 'void std::vector<_Tp, _Alloc>::_M_insert_dispatch(std::vector<_Tp, _Alloc>::iterator, _InputIterator, _InputIterator, std::__false_type) [with _InputIterator = const char*; _Tp = boost::basic_string_view<char, std::char_traits<char> >; _Alloc = std::allocator<boost::basic_string_view<char, std::char_traits<char> > >; std::vector<_Tp, _Alloc>::iterator = __gnu_cxx::__normal_iterator<boost::basic_string_view<char, std::char_traits<char> >*, std::vector<boost::basic_string_view<char, std::char_traits<char> > > >; typename std::_Vector_base<_Tp, _Alloc>::pointer = boost::basic_string_view<char, std::char_traits<char> >*]'
/usr/local/include/c++/6.1.0/bits/stl_vector.h:1100:4: [ skipping 12 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/local/include/boost/spirit/home/x3/operator/detail/sequence.hpp:496:24: required from 'static bool boost::spirit::x3::detail::parse_into_container_impl<boost::spirit::x3::sequence<L, R>, Context, RContext>::call(const parser_type&, Iterator&, const Iterator&, const Context&, RContext&, Attribute&) [with Iterator = const char*; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >; Left = boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >; Right = boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type>; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; boost::spirit::x3::detail::parse_into_container_impl<boost::spirit::x3::sequence<L, R>, Context, RContext>::parser_type = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >]'
/usr/local/include/boost/spirit/home/x3/core/detail/parse_into_container.hpp:287:74: required from 'bool boost::spirit::x3::detail::parse_into_container(const Parser&, Iterator&, const Iterator&, const Context&, RContext&, Attribute&) [with Parser = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >; Iterator = const char*; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/boost/spirit/home/x3/operator/kleene.hpp:32:48: required from 'bool boost::spirit::x3::kleene<Subject>::parse(Iterator&, const Iterator&, const Context&, RContext&, Attribute&) const [with Iterator = const char*; Context = boost::spirit::x3::unused_type; RContext = const boost::spirit::x3::unused_type; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >; Subject = boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> >]'
/usr/local/include/boost/spirit/home/x3/core/parse.hpp:35:68: required from 'bool boost::spirit::x3::parse_main(Iterator&, Iterator, const Parser&, Attribute&) [with Iterator = const char*; Parser = boost::spirit::x3::kleene<boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> > >; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
/usr/local/include/boost/spirit/home/x3/core/parse.hpp:60:26: required from 'bool boost::spirit::x3::parse(const Iterator&, Iterator, const Parser&, Attribute&) [with Iterator = const char*; Parser = boost::spirit::x3::kleene<boost::spirit::x3::sequence<boost::spirit::x3::raw_directive<boost::spirit::x3::plus<boost::spirit::x3::negated_char_parser<boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, char> > > >, boost::spirit::x3::literal_char<boost::spirit::char_encoding::standard, boost::spirit::x3::unused_type> > >; Attribute = std::vector<boost::basic_string_view<char, std::char_traits<char> > >]'
main.cpp:36:75: required from here
/usr/local/include/c++/6.1.0/bits/stl_algobase.h:324:18: error: no match for 'operator=' (operand types are 'boost::basic_string_view<char, std::char_traits<char> >' and 'const char')
*__result = *__first;
~~~~~~~~~~^~~~~~~~~~
In file included from main.cpp:4:0:
/usr/local/include/boost/utility/string_view.hpp:71:26: note: candidate: boost::basic_string_view<charT, traits>& boost::basic_string_view<charT, traits>::operator=(const boost::basic_string_view<charT, traits>&) [with charT = char; traits = std::char_traits<char>]
basic_string_view& operator=(const basic_string_view &rhs) BOOST_NOEXCEPT {
^~~~~~~~
/usr/local/include/boost/utility/string_view.hpp:71:26: note: no known conversion for argument 1 from 'const char' to 'const boost::basic_string_view<char, std::char_traits<char> >&'
我在这里错过了什么?
最佳答案
通过重载/特化 move_to
您基本上是在告诉 X3 如何从 boost::iterator_range
进行转换(实际上只是一对迭代器)到 boost::string_view
.不幸的是,它不知道两者是“等价的”(一个是 substitute
,另一个似乎是 Spirit 中使用的术语)。因此您的原始示例有效,因为您明确请求从迭代器转换为 string_view
但是这个失败了,因为 X3 缺少推断适当属性类型所需的信息。
具体问题似乎是here ,其中测试解析器的属性(在本例中为 raw_attribute_type
)是否与预期属性(boost::string_view
)的值类型兼容。此测试失败,然后选择了属性未“按原样传递”的代码路径,导致出现错误。
考虑到所有这些,似乎有两种可能的方法:明确请求转换或向 Spirit 提供有关属性兼容性的信息。
缺少我们在 Qi 中的一些助手(attr_cast
,as[]
),似乎在 X3 中强制进行属性转换的方法是创建一个具有您想要的实际类型的额外规则:
x3::rule<class str,boost::string_view> str= x3::raw[ +~char_('_')] >> '_';
auto const str_vec = *str;
您也可以(特别是如果您需要在多个规则中执行此操作)使用我见过 sehe 多次使用的方法(如 here )创建一个变量模板 lambda,可以像 as<T>(parser)
一样使用隐藏额外规则的创建并强制 parser
的属性转换成T
.
template<typename T>
auto as = [](auto p) { return rule<struct _, T>{} = as_parser(p); };
auto const str_vec = *as<boost::string_view>(x3::raw[ +~char_('_')] >> '_');
向Spirit 提供有关属性兼容性信息的方法似乎是专门化x3::traits::is_substitute
:
namespace boost {
namespace spirit { namespace x3 { namespace traits {
template <>
struct is_substitute<raw_attribute_type,boost::string_view> : boost::mpl::true_
{};
}}}
}
但是正如您在评论中提到的那样,这似乎不是记录在案的自定义点,因此我不确定使用它是否是个好主意。理想情况下,这将默认在 X3 中专门化,但正如 sehe 在 previous question 中评论的那样,迭代器引用的存储必须是连续的这一事实使情况复杂化。
关于c++ - 使用 boost::spirit::x3 解析为 vector<boost::string_view>,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39230186/
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这个问题在这里已经有了答案: What is the idiomatic Rust way to copy/clone a vector in a parameterized function? (
在我的程序中,我有一个整数 vector 的 vector 。现在我想从 vector 的 vector 中取出一个 vector 并在另一个 vector 容器中对其进行操作,但是我得到了错误...
我得到一个vector>数据由 OpenCV 提供。由于某些原因(例如偏移/缩放),我需要转换数据 Point至Point2f 。我怎样才能做到这一点? 例如: std::vector > conto
我有一个函数,该函数应使用来自字符串类型的给定 vector vector 中的某些元素初始化来自字符串类型的空 vector vector 。我的语法看起来像这样 std::vector> extr
我得到一个vector>数据由 OpenCV 提供。由于某些原因(例如偏移/缩放),我需要转换数据 Point至Point2f 。我怎样才能做到这一点? 例如: std::vector > conto
这里有很多类似的问题,但我没有真正找到任何可以特别回答我的问题的问题。 我有一个 vector 的 vector 作为类的属性。另一个属性是 bucket_count。我想将 vector 的 vec
如果我像这样创建一个 vector 的 vector : std::vector> myVectorOfVectors; 然后用一些东西填充它: std::vector myVector1; myVe
我正在用 C++ 编写自定义 vector 类。我对这样的代码有疑问: vector vec; vec.push_back(one); vec.push_back(two);
这是我发布的问题 c++ program for reading an unknown size csv file (filled only with floats) with constant (b
vector> a; for (int i=0;i v(i+1); iota(v.begin(),v.end(),1); a.push_back(v); } a.erase(a.beg
也许已经晚了,但我不明白为什么我会得到一个超出此代码范围的 vector 下标: int m = 3; int n = 2; std::vector> path(m, std::vector(n, 0
这个问题真的很奇怪,我似乎找不到任何导致它的原因。 所以这里有一个赋值运算符重载函数,鸟类和哺乳动物都是 vector 。 (下面是类) const Register& Register::opera
我怎么去 std::vector> 只是 std::vector> ?有真正有效的方法吗? 最佳答案 我会做这样的事情: #include #include int main() { //
我正在尝试将这些 vector 中的一些数据写入文本文件。当我运行代码时,它返回运行时错误。 Category、Product、Cart、Customer和Address都是struct 包含每个 g
显然它会因您使用的编译器而异,但我很好奇执行 vector> 时的性能问题与 vector*> ,尤其是在 C++ 中。具体来说: 假设您的外部 vector 已满,您想要开始将元素插入到第一个内部
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