The Spaceship Operator and Expression Rewriting

# Using <=> for Sorting

## Can <=> be used for sorting algorithms in C++20?

Yes, the <=> (spaceship) operator can be used for sorting algorithms in C++20. The spaceship operator allows you to define a single comparison function that can be used by sorting algorithms to determine the order ofÂ elements.

## How It Works

When you define the <=> operator for your custom type, you provide a way to compare two instances of that type. Sorting algorithms, like std::sort(), can then use this comparison logic to sort a collection of your customÂ objects.

## Example

Letâ€™s consider a Player class where we want to sort players by their scores using the spaceshipÂ operator:

#include <iostream>
#include <vector>
#include <algorithm>
#include <compare>
#include <string>

class Player {
public:
Player(std::string name, int score)
: Name{name}, Score{score} {}

std::strong_ordering operator<=>(
const Player& Other) const {
return Score <=> Other.Score;
}

std::string Name;
int Score;
};

int main() {
std::vector<Player> players{
{"Alice", 20}, {"Bob", 15}, {"Charlie", 25}
};

std::sort(players.begin(), players.end());

for (const auto& player : players) {
std::cout << player.Name
<< " - " << player.Score << "\n";
}
}
Bob - 15
Alice - 20
Charlie - 25

### Explanation

In this example, we define the <=> operator for the Player class to compare players by their scores. When we call std::sort(), it uses this comparison logic to sort the players in ascending order of theirÂ scores.

### Benefits

• Consistency: Defining the <=> operator ensures that all comparisons are consistent across your program.
• Simplicity: You write less code, as you only need to define one comparison operator.
• Flexibility: The same comparison logic can be reused in different contexts, such as sorting, searching, and other algorithms.

## Conclusion

Using the <=> operator with sorting algorithms in C++20 simplifies your code and ensures consistency in how your custom types are compared. It leverages the power of the spaceship operator to provide a clear and concise way to define sortingÂ logic.

This Question is from the Lesson:

### The Spaceship Operator and Expression Rewriting

A guide to simplifying our comparison operators using C++20 features

Answers to questions are automatically generated and may not have been reviewed.

This Question is from the Lesson:

### The Spaceship Operator and Expression Rewriting

A guide to simplifying our comparison operators using C++20 features

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