Blockchain Developer Certification Practice

What type of array in Solidity allows its size to change dynamically?

1. Fixed array

2. Dynamic array

3. Mapping

4. Struct

The correct answer is: Dynamic array

In Solidity, a dynamic array is a type of array that can change its size during execution. This flexibility is a key feature of dynamic arrays, allowing developers to add or remove elements without needing to define a fixed size at the outset. Unlike fixed arrays, where the size must be set upon creation and cannot be altered, dynamic arrays can grow or shrink, making them more versatile for various applications in smart contract development. Dynamic arrays are particularly useful when the number of elements cannot be anticipated ahead of time or when working with collections of data that may change over the lifecycle of a smart contract. Developers can use methods such as `.push()` to add elements or `.pop()` to remove elements from a dynamic array, effectively changing its size as needed. While mappings in Solidity allow for dynamic key-value associations, they do not function as arrays and do not have the concept of size like arrays do. Structs are used for grouping different types of data together, and fixed arrays have a static size that cannot be changed after declaration. Therefore, in terms of functionality related to size adjustment, dynamic arrays are the correct answer.