We have briefly touched on the concept of enumerations while discussing the layout of the Solidity file earlier in this chapter. Enums are value types comprising a pre-defined list of constant values. They are passed by values and each copy maintains its own value. Enums cannot be declared within functions and are declared within the global namespace of the contract.
Predefined constants are assigned consecutively, increasing integer values starting from zero.
The code illustration shown next declares an enum identified as a status consisting of five constant values—created, approved, provisioned, rejected, and deleted. They have integer values 0, 1, 2, 3, 4 assigned to them.
A instance of enum named myStatus is created with an initial value of provisioned.
The returnEnum function returns the status and it returns the integer value. It is to be noted that web3 and Decentralized Applications (DApp) do not understand an enum declared within a contract. They will get an integer value...