Blockchain Developer Certification Practice

Which function type in Solidity indicates the contract will not modify or read its data?

1. View

2. Constant

3. Pure

4. Payable

The correct answer is: Pure

In Solidity, the function type that indicates the contract will not modify or read its data is known as "pure." A pure function does not have access to the contract's state variables, meaning it cannot modify any state or read any data stored in the contract. Instead, it can only use the parameters passed to it for computations and return results based solely on those inputs. This characteristic makes pure functions useful for stateless computations and helps in optimizing gas costs when transactions are executed on the blockchain. By contrast, view functions are designed to read data from the contract’s state but not modify it. They can access state variables and return their values without changing the contract's state. Constant was a keyword used in earlier versions of Solidity before it was replaced by "pure" and "view," making it less relevant in current Solidity development. Payable functions, on the other hand, are specifically designed to accept Ether as part of the transaction and can modify the contract's state, which does not align with the characteristics of pure functions. Thus, "pure" is the correct function type that signifies no reading or modifying of contract data occurs.