How can I use C++ to sort an array alphabetically into a new array?

Question

I have an array called g_Parameters that I am looking to sort alphabetically in a new array called g_SortedParameters.

I have provided the code for the array. I need to sort it alphabetically to use in a log, but without g_Parameters itself being sorted alphabetically as other code relies on the indexing as it stands.

const unsigned long ParamsCount = 6;
const TCHAR * const g_Parameters[ParamsCount] =
{ TEXT("AllowFatal"), TEXT("Variant"), TEXT("EnableLogs"),
  TEXT("AllowRescan"), TEXT("Path"), TEXT("Filter"),
};

I would appreciate any help with sorting this array into a new array. I'm happy to provide more information if it is required.

The cleanest would be to copy the content of array with std::copy and sort the copy with std::sort, but I'm not sure how well is that working with winapi. — Yksisarvinen
– Yksisarvinen, Commented Sep 4, 2019 at 12:48
std::partial_sort_copy() can be used to copy and sort at the same time without modifying the original. — Shawn
– Shawn, Commented Sep 4, 2019 at 12:52
ParamsCount = 3? I would count 6 elements in array. but missing {. — Jarod42
– Jarod42, Commented Sep 4, 2019 at 12:52
Whenever you have a problem like this, your first step should be to browse through the list of algorithms provided by the standard library. — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Sep 4, 2019 at 13:07

Shawn · Accepted Answer · 2019-09-04 13:04:47Z

3

One way is to use std::partial_sort_copy() which, despite the name, can be used to sort a copy of an entire array without modifying the order of the original.

Demonstration:

#include <algorithm>
#include <array>
#include <iostream>

template<class T, std::size_t N>
void print_array(const std::array<T, N> &ar) {
  for (const auto &elem : ar) {
    std::cout << elem << ' ';
  }
  std::cout << '\n';
}

int main() {
  std::array<int, 5> orig = { 10, 8, 1, 4, 3 }, sorted;
  std::partial_sort_copy(orig.begin(), orig.end(), sorted.begin(), sorted.end());
  print_array(orig);
  print_array(sorted);
}

when compiled and run will print out

10 8 1 4 3 
1 3 4 8 10

edited Sep 4, 2019 at 13:04

answered Sep 4, 2019 at 12:59

Shawn

53.9k3 gold badges29 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Lightness Races in Orbit Over a year ago

However, you'll also need to teach predicates since the array contains C-strings.

Shawn Over a year ago

@LightnessRacesinOrbit Or just tell OP to use std::string instead of whatever TCHAR * and TEXT() are. This is just to give him an idea of how to use the function. Adding a custom comparison function is left as an exercise for the reader.

Lightness Races in Orbit Over a year ago

Perhaps as a bonus, but as it currently stands this answer is insufficient for the question posed. When they apply this solution, they will get the wrong answer. You could leave the predicate as an exercise to the reader, but you should at least mention that the exercise exists.

Steven Over a year ago

@Shawn - "Or just tell OP to use std::string instead of whatever TCHAR * and TEXT() are." No. These can't be changed like that and must remain as they are.

Collectives™ on Stack Overflow

How can I use C++ to sort an array alphabetically into a new array?

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related