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

heap or stack

Answer

local or global

Answer

mutable or immutable

Question 2

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

Accepted Answer

storage

Answer

memory

Answer

calldata

Answer

stack

Question 3

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

Accepted Answer

uint256[] public myArray;

Answer

uint256[dynamic] public myArray;

Answer

array<uint256> public myArray;

Answer

dynamic uint256[] public myArray;

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

An error is thrown

Answer

null

Answer

undefined

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 only contain value types

Answer

Structs cannot be used as mapping values

Answer

Structs are always stored in memory

Question 6

What is the key difference between a fixed-size array and a dynamic array in Solidity?

Accepted Answer

Fixed-size arrays have their length set at compile time while dynamic arrays can grow

Answer

Fixed-size arrays can only hold value types

Answer

Dynamic arrays are always cheaper to use

Answer

Fixed-size arrays are stored in memory while dynamic arrays go to storage

Question 7

Which built-in array operations are available for a dynamic storage array in Solidity?

Accepted Answer

push(value) and pop()

Answer

remove(index) and insert(index, value)

Answer

splice(start, count) and concat(array)

Answer

append(value) and trim()