What data types in programming can be mutable during runtime?

In programming, the following data types can be mutable:

• Arrays and collections: for example, arrays, lists, dictionaries, sets — their contents can be changed after creation.
• Class and struct objects: object fields can be modified if they are not declared as constants.
• Variables of basic types: such as int, float, bool — their values can be changed.
• In iOS (Swift/Objective-C):
  • In Swift — variables declared with var are mutable, while those with let are not.
  • Arrays, dictionaries, and sets declared with var can be modified (adding, removing elements).

Example in Swift:

var numbers = [1, 2, 3]
numbers.append(4) // mutable array

let constantNumbers = [1, 2, 3]
// constantNumbers.append(4) // error, as the array is declared with let