operator==,!=,<,<=,>,>=,<=>(std::basic_string)
定义于头文件 <string>
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比较二个 basic_string 对象 |
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(1) | ||
template< class CharT, class Traits, class Alloc > bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
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template< class CharT, class Traits, class Alloc > constexpr bool |
(C++20 起) | |
(2) | ||
template< class CharT, class Traits, class Alloc > bool operator!=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator!=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
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(3) | ||
template< class CharT, class Traits, class Alloc > bool operator<( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator<( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
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(4) | ||
template< class CharT, class Traits, class Alloc > bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
|
(5) | ||
template< class CharT, class Traits, class Alloc > bool operator>( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator>( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
|
(6) | ||
template< class CharT, class Traits, class Alloc > bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 前) | |
template< class CharT, class Traits, class Alloc > bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++14 起) (C++20 前) |
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template< class CharT, class Traits, class Alloc > constexpr /*comp-cat*/ |
(7) | (C++20 起) |
比较一个 basic_string 与 T 的空终止数组 |
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(8) | ||
template< class CharT, class Traits, class Alloc > bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > constexpr bool operator==( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 起) | |
template< class CharT, class Traits, class Alloc > bool operator==( const CharT* lhs, |
(C++20 前) | |
(9) | ||
template< class CharT, class Traits, class Alloc > bool operator!=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > bool operator!=( const CharT* lhs, |
(C++20 前) | |
(10) | ||
template< class CharT, class Traits, class Alloc > bool operator<( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > bool operator<( const CharT* lhs, |
(C++20 前) | |
(11) | ||
template< class CharT, class Traits, class Alloc > bool operator<=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > bool operator<=( const CharT* lhs, |
(C++20 前) | |
(12) | ||
template< class CharT, class Traits, class Alloc > bool operator>( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > bool operator>( const CharT* lhs, |
(C++20 前) | |
(13) | ||
template< class CharT, class Traits, class Alloc > bool operator>=( const std::basic_string<CharT,Traits,Alloc>& lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > bool operator>=( const CharT* lhs, |
(C++20 前) | |
template< class CharT, class Traits, class Alloc > constexpr /*comp-cat*/ |
(14) | (C++20 起) |
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 或 std::lexicographical_compare_three_way (C++20 起)的函数进行比较。
三路比较运算符的返回类型( /*comp-cat*/ )为 Traits::comparison_category ,若它存在,否则为 std::weak_ordering 。 |
(C++20 起) |
basic_string
对象。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
复杂度
与字符串大小成线性。
注解
若至少一个参数拥有类型 std::string 、 std::wstring 、 std::u8string 、 std::u16string 或 std::u32string ,则 |
(C++20 起) |