From cppreference.com
voidsort(); (1) template<classCompare>voidsort(Comparecomp); (2) Sorts the elements and preserves the order of equivalent elements. No references or iterators become invalidated.
1) Elements are compared using operator<.
2) Elements are compared using comp.
If an exception is thrown, the order of elements in *this is unspecified.
Parameters
comp - comparison function object (i.e. an object that satisfies the requirements of
) which returns true if the first argument is less than (i.e. is ordered before) the second. The signature of the comparison function should be equivalent to the following:
boolcmp(constType1&a,constType2&b);
While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) Type1 and Type2 regardless of
(thus, Type1& is not allowed, nor is Type1 unless for Type1 a move is equivalent to a copy(since C++11)).
The types Type1 and Type2 must be such that an object of type list<T,Allocator>::const_iterator can be dereferenced and then implicitly converted to both of them.
Type requirements -Compare must meet the requirements of
. Complexity
Given N as
:
1) Approximately N·log(N) comparisons using operator<.
2) Approximately N·log(N) applications of the comparison function comp.
Notes
requires random access iterators and so cannot be used with list. This function also differs from
in that it does not require the element type of the list to be swappable, preserves the values of all iterators, and performs a stable sort.
Example
Run this code
#include<functional>#include<iostream>#include<list>std::ostream&operator<<(std::ostream&ostr,conststd::list<int>&list){for(constinti:list)ostr<<' '<<i;returnostr;}intmain(){std::list<int>list{8,7,5,9,0,1,3,2,6,4};std::cout<<"initially: "<<list<<'\n';list.sort();std::cout<<"ascending: "<<list<<'\n';list.sort(std::greater<int>());std::cout<<"descending:"<<list<<'\n';}Output:
initially: 8 7 5 9 0 1 3 2 6 4 ascending: 0 1 2 3 4 5 6 7 8 9 descending: 9 8 7 6 5 4 3 2 1 0 Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++98 it was unclear whether iterators and/or references will be invalidated keep valid See also
reverses the order of the elements
(public member function)