Benefits of the Spaceship Operator

The spaceship operator <=> introduced in C++20 offers several benefits over traditional comparison operators:

Simplified Code

The <=> operator consolidates the functionality of multiple comparison operators into one. This means you only need to define one operator instead of six (<, <=, >, >=, ==, !=).

This reduces boilerplate code and minimizes the chances of inconsistencies or errors.

Automatic Generation of Comparison Operators

When you define the <=> operator, the compiler can automatically generate the traditional comparison operators.

This ensures consistency and correctness in comparisons, as all operators are based on the same logic.

Clear Semantics

The spaceship operator provides a clear and unified way to compare objects. It explicitly returns whether one object is less than, equal to, or greater than another, encapsulating all comparison outcomes in a single operation.

This can make your code more readable and maintainable.

Performance Optimization

In many cases, using the <=> operator can be more efficient because the compiler can optimize the comparison logic.

For example, when comparing complex objects, the spaceship operator allows the compiler to generate more efficient code by avoiding redundant checks.

Example

Here’s an example demonstrating the benefits of the <=> operator:

1#include <compare>
2#include <iostream>
3
4class Number {
5 public:
6  std::strong_ordering operator<=>(
7    const Number& Other) const {
8    return Value <=> Other.Value;
9  }
10
11  bool operator==(const Number& Other) const {
12    return Value == Other.Value;
13  }
14
15  int Value;
16};
17
18int main() {
19  Number A{1};
20  Number B{2};
21
22  if (A < B) {
23    std::cout << "A is less than B\n";
24  }
25  if (A <= B) {
26    std::cout << "A is less than or equal to B\n";
27  }
28  if (A > B) {
29    std::cout << "A is greater than B\n";
30  }
31  if (A >= B) {
32    std::cout << "A is greater than or equal to B\n";
33  }
34  if (A == B) {
35    std::cout << "A is equal to B\n";
36  }
37  if (A != B) {
38    std::cout << "A is not equal to B\n";
39  }
40}

1A is less than B
2A is less than or equal to B
3A is not equal to B

In this example, we only defined the <=> operator for the Number class, yet we can use all traditional comparison operators. This demonstrates how the spaceship operator simplifies our code while maintaining clarity and performance.