Blockchain Developer Certification Practice

Is the concept of null or undefined present in Solidity?

1. True

2. False

3. It may exist under certain conditions

4. Only for local variables

The correct answer is: False

In Solidity, the concept of null or undefined as it exists in other programming languages does not apply. Solidity, which is primarily used for writing smart contracts on the Ethereum blockchain, employs types and initialization behaviors that eliminate the notions of null or undefined. If a variable is uninitialized, it will have a default value based on its type – for example, integer types default to zero, boolean types default to false, and addresses default to the zero address. This design choice ensures type safety and reduces the risk of errors that can arise from nil values that might be exploited in other programming environments. Since uninitialized variables can't be null or undefined, the assertion that such concepts exist in Solidity is fundamentally incorrect.