std::ranges::sort
| Defined in header <algorithm>
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| Call signature |
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| template< std::random_access_iterator I, std::sentinel_for<I> S, class Comp = ranges::less, class Proj = std::identity > |
(1) | (since C++20) |
| template< std::random_access_range R, class Comp = ranges::less, class Proj = std::identity > |
(2) | (since C++20) |
Sorts the elements in the range [first, last) in non-descending order. The order of equivalent elements is not guaranteed to be preserved.
A sequence is sorted with respect to a comparator comp if for any iterator it pointing to the sequence and any non-negative integer n such that it + n is a valid iterator pointing to an element of the sequence, std::invoke(comp, std::invoke(proj, *(it + n)), std::invoke(proj, *it)) evaluates to false.
comp.r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.The function-like entities described on this page are niebloids, that is:
- Explicit template argument lists may not be specified when calling any of them.
- None of them is visible to argument-dependent lookup.
- When one of them is found by normal unqualified lookup for the name to the left of the function-call operator, it inhibits argument-dependent lookup.
In practice, they may be implemented as function objects, or with special compiler extensions.
Parameters
| first, last | - | iterator-sentinel defining the range to sort |
| r | - | the range to sort |
| comp | - | comparison to apply to the projected elements |
| proj | - | projection to apply to the elements |
Return value
An iterator equal to last.
Complexity
O(N·log(N)) comparisons and projections, where N = ranges::distance(first, last).
Possible implementation
| This section is incomplete Reason: Can we just use heap sort ( make_heap and sort_heap) for short? |
Example
#include <algorithm> #include <array> #include <functional> #include <iomanip> #include <iostream> void print(auto const& seq) { for (auto const& elem : seq) { std::cout << elem << ' '; } std::cout << '\n'; } struct Particle { std::string name; double mass; // MeV template<class Os> friend Os& operator<< (Os& os, Particle const& p) { return os << "\n" << std::left << std::setw(8) << p.name << " : " << p.mass; } }; int main() { std::array s = {5, 7, 4, 2, 8, 6, 1, 9, 0, 3}; namespace ranges = std::ranges; // sort using the default operator< ranges::sort(s); print(s); // sort using a standard library compare function object ranges::sort(s, ranges::greater()); print(s); // sort using a custom function object struct { bool operator()(int a, int b) const { return a < b; } } customLess; ranges::sort(s.begin(), s.end(), customLess); print(s); // sort using a lambda expression ranges::sort(s, [](int a, int b) { return a > b; }); print(s); // sort with projection Particle particles[] { {"Electron", 0.511}, {"Muon", 105.66}, {"Tau", 1776.86}, {"Positron", 0.511}, {"Proton", 938.27}, {"Neutron", 939.57}, }; ranges::sort(particles, {}, &Particle::name); //< sort by name print(particles); ranges::sort(particles, {}, &Particle::mass); //< sort by mass print(particles); }
Output:
0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0 Electron : 0.511 Muon : 105.66 Neutron : 939.57 Positron : 0.511 Proton : 938.27 Tau : 1776.86 Electron : 0.511 Positron : 0.511 Muon : 105.66 Proton : 938.27 Neutron : 939.57 Tau : 1776.86
See also
| (C++20) |
sorts the first N elements of a range (niebloid) |
| (C++20) |
sorts a range of elements while preserving order between equal elements (niebloid) |
| sorts a range into ascending order (function template) |