std::forward_list<T,Allocator>::sort

 

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std::forward_list

Member functions
forward_list::forward_list forward_list::~forward_list forward_list::operator= forward_list::assign forward_list::assign_range (C++23)   forward_list::get_allocator Element access forward_list::front Iterators forward_list::before_beginforward_list::cbefore_begin forward_list::beginforward_list::cbegin forward_list::endforward_list::cend Capacity forward_list::empty forward_list::max_size	Modifiers forward_list::clear forward_list::emplace_front forward_list::push_front forward_list::insert_after forward_list::emplace_after forward_list::erase_after forward_list::insert_range_after (C++23) forward_list::prepend_range (C++23) forward_list::pop_front forward_list::resize forward_list::swap Operations forward_list::merge forward_list::splice_after forward_list::removeforward_list::remove_if forward_list::reverse forward_list::unique forward_list::sort
Non-member functions
operator==operator<=> (C++20) swap(std::forward_list) erase(std::forward_list)erase_if(std::forward_list) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides (C++17)

 

void sort();	(1)	(since C++11)
template< class Compare > void sort( Compare comp );	(2)	(since C++11)

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 Compare) 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: bool cmp(const Type1& a, const Type2& 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 value category (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 forward_list<T,Allocator>::const_iterator can be dereferenced and then implicitly converted to both of them. ​
Type requirements
- Compare must meet the requirements of Compare.

Return value

(none)

Complexity

Given \(\scriptsize N\)N as std::distance(begin(), end()):

1) Approximately \(\scriptsize N \cdot log(N)\)N·log(N) comparisons using operator<.

2) Approximately \(\scriptsize N \cdot log(N)\)N·log(N) applications of the comparison function comp.

Notes

std::sort requires random access iterators and so cannot be used with forward_list. This function also differs from std::sort in that it does not require the element type of the forward_list to be swappable, preserves the values of all iterators, and performs a stable sort.

Example

Run this code

#include <functional>
#include <iostream>
#include <forward_list>
 
std::ostream& operator<<(std::ostream& ostr, const std::forward_list<int>& list)
{
    for (const int i : list)
        ostr << ' ' << i;
    return ostr;
}
 
int main()
{
    std::forward_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

See also

reverse

reverses the order of the elements (public member function)