operator==,!=,<,<=,>,>=(std::basic_string)

 

C++

语言

头文件

库概念

语言支持库

诊断库

工具库

字符串库

容器库

算法库

迭代器库

数值库

输入/输出库

本地化库

正则表达式库 (C++11)

原子操作库 (C++11)

线程支持库 (C++11)

文件系统库 (C++17)

技术规范

 

字符串库

空终止字符串

字节字符串

多字节字符串

宽字符串

类

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

成员函数 basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator 元素访问 basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str basic_string::operator basic_string_view (C++17) 迭代器 basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) 容量 basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)

操作 basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::swap 查找 basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of 常量 basic_string::npos

非成员函数 operator+ operator==operator!=operator<operator>operator<=operator>= swap(std::basic_string) operator<<operator>> getline stoistolstoll (C++11) (C++11) (C++11) stoulstoull (C++11) (C++11) stofstodstold (C++11) (C++11) (C++11) to_string (C++11) to_wstring (C++11) operator""s (C++14) 辅助类 hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string> (C++11) (C++11) (C++11) (C++11) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string> (C++20) (C++20) (C++20) (C++20) 推导指引(C++17)

 

比较二个 basic_string 对象
template< class CharT, class Traits, class Alloc > bool operator==( const basic_string<CharT,Traits,Alloc>& lhs,                  const basic_string<CharT,Traits,Alloc>& rhs );	(1)
template< class CharT, class Traits, class Alloc > bool operator!=( const basic_string<CharT,Traits,Alloc>& lhs,                  const basic_string<CharT,Traits,Alloc>& rhs );	(2)
template< class CharT, class Traits, class Alloc > bool operator<( const basic_string<CharT,Traits,Alloc>& lhs,                 const basic_string<CharT,Traits,Alloc>& rhs );	(3)
template< class CharT, class Traits, class Alloc > bool operator<=( const basic_string<CharT,Traits,Alloc>& lhs,                  const basic_string<CharT,Traits,Alloc>& rhs );	(4)
template< class CharT, class Traits, class Alloc > bool operator>( const basic_string<CharT,Traits,Alloc>& lhs,                 const basic_string<CharT,Traits,Alloc>& rhs );	(5)
template< class CharT, class Traits, class Alloc > bool operator>=( const basic_string<CharT,Traits,Alloc>& lhs,                  const basic_string<CharT,Traits,Alloc>& rhs );	(6)
比较 basic_string 对象和 T 的空终止数组
template< class CharT, class Traits, class Alloc > bool operator==( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(7)
template< class CharT, class Traits, class Alloc > bool operator==( const basic_string<CharT,Traits,Alloc>& lhs, const CharT* rhs );	(7)
template< class CharT, class Traits, class Alloc > bool operator!=( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(8)
template< class CharT, class Traits, class Alloc > bool operator!=( const basic_string<CharT,Traits,Alloc>& lhs, const CharT* rhs );	(8)
template< class CharT, class Traits, class Alloc > bool operator<( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(9)
template< class CharT, class Traits, class Alloc > bool operator<( const basic_string<CharT,Traits,Alloc>& lhs,  const CharT* rhs );	(9)
template< class CharT, class Traits, class Alloc > bool operator<=( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(10)
template< class CharT, class Traits, class Alloc > bool operator<=( const basic_string<CharT,Traits,Alloc>& lhs, const CharT* rhs );	(10)
template< class CharT, class Traits, class Alloc > bool operator>( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(11)
template< class CharT, class Traits, class Alloc > bool operator>( const basic_string<CharT,Traits,Alloc>& lhs, const CharT* rhs );	(11)
template< class CharT, class Traits, class Alloc > bool operator>=( const CharT* lhs, const basic_string<CharT,Traits,Alloc>& rhs );	(12)
template< class CharT, class Traits, class Alloc > bool operator>=( const basic_string<CharT,Traits,Alloc>& lhs, const CharT* rhs );	(12)

比较 string 与另一 string 或 CharT 的空终止数组的内容。

所有比较通过 compare() 成员函数进行（它自身以 Traits::compare() 定义）：

• 若 lhs 与 rhs 的大小相等，且 lhs 中的每个字符有在 rhs 中在同一位置的等价字符，则二个字符串相等。

• 顺序比较按字典序——以等价于 std::lexicographical_compare 的函数进行比较。

1-6) 比较二个 basic_string 对象。

7-12) 比较 basic_string 对象和 CharT 的空终止数组。

参数

lhs, rhs

-

要比较内容的字符串

返回值

若对应比较关系成立则为 true ，否则为 false 。

异常

1-6)

（无）	(C++14 前)
noexcept 规定：   noexcept	(C++14 起)

7-12) （无）

复杂度

与字符串大小成线性。