Rust, Software Development

Enum Variants And Match Expressions In Rust

There are a few ways to define an enum variant and, as a result, to use it when creating match expressions. We can define a variant in three ways –  one-word, Tuple-like, or Struct-like.

Match One-Word Enum Variants

Let’s say we want an enum based on the days of a week, as shown below. Each variant is case-sensitive and represents a day in a week.

To use the variants with the match keyword, we construct match expressions as follows. There are only six match expressions for seven days – one expression matches for Saturday or Sunday!

We don’t have many options for this type of variant. For each expression, we can only use the variant itself or the OR (|) operator to specify multiple variants.

The codes output the following.

Match Tuple-Like Enum Variants

We can also create enum variants like tuples and use them in match expressions differently from the previous examples.

The codes output the following.

Struct-like Enum Variants

Another way to create variants is by defining them like structs. How we use them with match expressions is somewhat similar to tuple-like variants.

Each struct-like variant can vary from the other variants.

The codes output the following.

Mixed-Style Variants

In Rust, we can use different styles of variant creation within the same enum. Consider the following codes.

Now we have a one-word January, the tuple-like October, and the rest of the variants are struct in form.

The codes output the following.

We tested the codes using Rust 1.42.0.

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