Compare
C++概念：比较
概念Compare是用户提供的函数对象类型中的一些标准库工具所期望的一组需求。
应用于类型对象的函数调用操作的返回值。Compare，何时上下文转换到bool，产量true如果调用的第一个参数出现在严格弱序关系由此引发Compare类型，以及false否则。
就像任何BinaryPredicate，该表达式的求值不允许调用取消引用的迭代器的非Const成员函数。
所需
类型T满足Compare如果。
- 类型
T满足BinaryPredicate，和给予。
comp，类型的对象Compare
equiv(a, b)，相当于!comp(a, b) && !comp(b, a)
下列表达式必须有效并具有指定的效果。
| Expression | Return type | Requirements |
|---|---|---|
| comp(a, b) | implicitly convertible to bool | Establishes strict weak ordering relation with the following properties For all a, comp(a,a)==false If comp(a,b)==true then comp(b,a)==false if comp(a,b)==true and comp(b,c)==true then comp(a,c)==true |
| equiv(a, b) | bool | Establishes equivalence relationship with the following properties For all a, equiv(a,a)==true If equiv(a,b)==true, then equiv(b,a)==true If equiv(a,b)==true and equiv(b,c)==true, then equiv(a,c)==true |
- 为所有人
a，，，comp(a,a)==false
- 如果
comp(a,b)==true然后comp(b,a)==false
- 如果
comp(a,b)==true和comp(b,c)==true然后comp(a,c)==true
`equiv(a, b)` `bool` Establishes equivalence relationship with the following properties
- 为所有人
a，，，equiv(a,a)==true
- 如果
equiv(a,b)==true，然后equiv(b,a)==true
- 如果
equiv(a,b)==true和equiv(b,c)==true，然后equiv(a,c)==true
注：comp诱导严格全序关于由equiv...
标准库
以下标准库设施期望Compare类型。
| set | collection of unique keys, sorted by keys (class template) |
|---|---|
| map | collection of key-value pairs, sorted by keys, keys are unique (class template) |
| multiset | collection of keys, sorted by keys (class template) |
| multimap | collection of key-value pairs, sorted by keys (class template) |
| priority_queue | adapts a container to provide priority queue (class template) |
| sort | sorts a range into ascending order (function template) |
| sort | sorts the elements (public member function of std::forward_list) |
| sort | sorts the elements (public member function of std::list) |
| stable_sort | sorts a range of elements while preserving order between equal elements (function template) |
| partial_sort | sorts the first N elements of a range (function template) |
| partial_sort_copy | copies and partially sorts a range of elements (function template) |
| is_sorted (C++11) | checks whether a range is sorted into ascending order (function template) |
| is_sorted_until (C++11) | finds the largest sorted subrange (function template) |
| nth_element | partially sorts the given range making sure that it is partitioned by the given element (function template) |
| lower_bound | returns an iterator to the first element not less than the given value (function template) |
| upper_bound | returns an iterator to the first element greater than a certain value (function template) |
| binary_search | determines if an element exists in a certain range (function template) |
| equal_range | returns range of elements matching a specific key (function template) |
| merge | merges two sorted ranges (function template) |
| merge | merges two sorted lists (public member function of std::forward_list) |
| merge | merges two sorted lists (public member function of std::list) |
| inplace_merge | merges two ordered ranges in-place (function template) |
| includes | returns true if one set is a subset of another (function template) |
| set_difference | computes the difference between two sets (function template) |
| set_intersection | computes the intersection of two sets (function template) |
| set_symmetric_difference | computes the symmetric difference between two sets (function template) |
| set_union | computes the union of two sets (function template) |
| push_heap | adds an element to a max heap (function template) |
| pop_heap | removes the largest element from a max heap (function template) |
| make_heap | creates a max heap out of a range of elements (function template) |
| sort_heap | turns a max heap into a range of elements sorted in ascending order (function template) |
| is_heap (C++11) | checks if the given range is a max heap (function template) |
| is_heap_until (C++11) | finds the largest subrange that is a max heap (function template) |
| max | returns the greater of the given values (function template) |
| max_element | returns the largest element in a range (function template) |
| min | returns the smaller of the given values (function template) |
| min_element | returns the smallest element in a range (function template) |
| minmax (C++11) | returns the smaller and larger of two elements (function template) |
| minmax_element (C++11) | returns the smallest and the largest elements in a range (function template) |
| lexicographical_compare | returns true if one range is lexicographically less than another (function template) |
| next_permutation | generates the next greater lexicographic permutation of a range of elements (function template) |
| prev_permutation | generates the next smaller lexicographic permutation of a range of elements (function template) |
© cppreference.com
在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。
