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What is an indexer, and how does it let a custom class support square-bracket syntax like an array? How do you overload the '+' operator to support adding two custom objects together? Which operators can be overloaded in C#, and which ones (like && and ||) generally CANNOT be overloaded directly? How do you define a custom implicit or explicit conversion operator between your type and another type? How would you implement a multi-dimensional indexer, like a Matrix class supporting matrix[row, col] syntax? How do you overload the true/false operators to make a custom type usable directly in an 'if' statement or as a boolean condition? How would you implement a fluent, chainable custom '+' operator overload for building an immutable Vector3 math library, and what performance consideration applies for structs? How do you implement the 'checked' operator overload variant (introduced in C# 11) to provide overflow-checking behavior for a custom numeric type? How would you use an indexer together with a custom enumerator (implementing IEnumerable) to build a fully iterable, indexable custom collection class?
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C# › Indexers & Operator Overloading

How do you overload comparison operators like < and >, and what consistency rule must they maintain relative to Equals()?

Intermediate

Answer

Overload '<' and '>' as static operator methods, and their logic must be CONSISTENT with any overloaded '==' and Equals() — specifically, if a.Equals(b) is true, then neither a < b nor a > b should also be true, maintaining a coherent total ordering that doesn't contradict equality.
public struct Money : IComparable<Money> {
  public decimal Amount;
  public static bool operator <(Money a, Money b) => a.Amount < b.Amount;
  public static bool operator >(Money a, Money b) => a.Amount > b.Amount;
  public int CompareTo(Money other) => Amount.CompareTo(other.Amount); // must agree with < and >
}
Real-world example Allowing natural comparison syntax (a < b) for a Money or custom numeric type used in sorting and range checks.

Common follow-ups: If you overload '<', does C# require you to also overload '>' — and what other operator pairing rules exist?

Equality: Equals GetHashCode & IEquatable
All 10 Indexers & Operator Overloading questions