As in other programming languages, enumerations help us to define our own data type that consists of a list of named constants, to ease reading the code. Here, we define an enumeration representing the auction status, with two possible states: CANCELLED or STARTED.

First, we define our enumeration auction_state by using the enum keyword, as follows: enum auction_state { CANCELLED,STARTED }.

Then, we declare a variable of the auction_state type: auction_state public STATE;.

The enum values are converted into integers and numbered in the order that they are defined, starting at zero. If you want to get the value of your declared enum constants, use an explicit conversion uint(STATE). Instead of using the corresponding integer value, you can directly use the enum constants, as follows: auction_state.STARTED (equals 0) or auction_state.CANCELLED (equals 1).