Solidity Solidity Data Types and Storage 2

Question 1

What data location must be explicitly specified for reference type parameters in Solidity functions?

Accepted Answer

memory, storage, or calldata

Answer

Reference type parameters must declare a data location — memory, storage, or calldata — so the compiler knows where the data resides.

Question 2

What is the default data location for state variables in a Solidity contract?

Accepted Answer

storage

Answer

State variables are always stored in storage (on-chain persistent storage) by default, which is why they persist between function calls.

Question 3

Which of the following correctly declares a dynamic array of uint256 as a state variable?

Accepted Answer

uint256[] public myArray;

Answer

Dynamic arrays in Solidity are declared with empty square brackets [], omitting a size to allow the array to grow at runtime.

Question 4

What does a Solidity mapping return for a key that has never been set?

Accepted Answer

The default zero value for the value type

Answer

Mappings return the default zero value of their value type (e.g., 0 for uint, false for bool) for any key that has not been explicitly set.

Question 5

Which statement about structs in Solidity is correct?

Accepted Answer

Structs can contain other structs but not directly recursive self-references

Answer

Structs can nest other struct types but cannot contain a direct recursive reference to themselves, as that would create an infinitely-sized type.

Solidity Practice Test