std::string的Copy-on-Write:不如想象中美好 通过查看 gcc 源代码 gcc-12.2.0 <string.h> 可以发现 string 实际上是 basic_string 模板的 char 版本特化。 namespace pmr { template<typename _Tp> class polymorphic_allocator; template<typename _CharT,...
(long double val); namespace pmr { template <class charT, class traits = char_traits<charT>> using basic_string = std::basic_string<charT, traits, polymorphic_allocator<charT>>; using string = basic_string<char>; using u8string = basic_string<char8_t>; using u16string = basic_string<...
namespacepmr{ template<classCharT,classTraits=std::char_traits<CharT>> usingbasic_string=std::basic_string<CharT, Traits, std::polymorphic_allocator<CharT>> } (C++17 起) 类模板basic_string存储并操纵作为非数组平凡标准布局类型的仿char对象序列。该类既不依赖字符类型,亦不依赖该类型上的原生操作。操...
pmr::basic_string::reserve保留了一个以上的需求。在本例中，它保留了96个字节，比您拥有的80个字节...
#include <iostream> #include <string> #include <string_view> #include <functional> #include <memory_resource> using namespace std::literals; int main() { auto sv = "Stand back! I've got jimmies!"sv; std::string s(sv); std::pmr::string pmrs(sv); // 使用默认分配器 std::cout <...
std::basic_string - std::basic_string Synopsis Defined in header <string> template< class CharT, class Traits = std::char_traits<CharT>,(1) class Allocator = std::allocator<CharT> > class basic_string; namespace pmr { template <class CharT, class Traits = std::char_traits<CharT>> ...
(long double val); namespace pmr { template<class CharT, class Traits = char_traits<CharT>> using basic_string = std::basic_string<CharT, Traits, polymorphic_allocator<CharT>>; using string = basic_string<char>; using u8string = basic_string<char8_t>; using u16string = basic_string<...
#include <functional> #include <iostream> #include <memory_resource> #include <string> #include <string_view> using namespace std::literals; int main() { auto sv = "Stand back! I've got jimmies!"sv; std::string s(sv); std::pmr::string pmrs(sv); // 使用默认分配器 std::cout <...
(long double val); namespace pmr { template<class CharT, class Traits = char_traits<CharT>> using basic_string = std::basic_string<CharT, Traits, polymorphic_allocator<CharT>>; using string = basic_string<char>; using u8string = basic_string<char8_t>; using u16string = basic_string<...
classAllocator=std::allocator<CharT> >classbasic_string; (1) namespace { template< classCharT, classTraits=std::char_traits<CharT> >usingbasic_string= std::basic_string<CharT, Traits,std::pmr::polymorphic_allocator<CharT>>; } (2)