Symbol type and immutability in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Symbol in Ruby?

A Symbol is a lightweight, immutable identifier used mainly as names or keys. It is unique and stored only once in memory.

beginner

Why are Symbols considered immutable in Ruby?

Symbols cannot be changed after creation. This immutability means their value and identity stay constant throughout the program.

intermediate

How do Symbols differ from Strings in Ruby?

Symbols are immutable and stored once, making them memory-efficient for repeated use. Strings are mutable and can have many copies in memory.

intermediate

What happens if you create the same Symbol multiple times?

Ruby reuses the same Symbol object for identical names, so all references point to the same memory location.

beginner

Give an example of creating a Symbol in Ruby.

You create a Symbol by prefixing a name with a colon, like :example. This creates a Symbol named 'example'.

Which of the following is a Symbol in Ruby?

A 'my_symbol'

B "my_symbol"

C my_symbol

D :my_symbol

Symbols start with a colon, like :my_symbol.

What is true about Symbols in Ruby?

A They are immutable and unique.

B They are mutable and can be changed.

C They consume more memory than strings.

D They are only used for numbers.

Symbols are immutable and unique identifiers.

If you create :apple twice in Ruby, what happens?

A Two different Symbol objects are created.

B An error occurs.

C The same Symbol object is reused.

D A new String is created instead.

Ruby reuses the same Symbol object for identical names.

Which is a benefit of using Symbols over Strings as keys in hashes?

A Symbols use less memory and are faster.

B Symbols can be changed anytime.

C Symbols are mutable.

D Symbols are slower to compare.

Symbols are immutable and stored once, making them memory-efficient and faster for lookups.

How do you create a Symbol named 'status' in Ruby?

A "status"

B :status

C 'status'

D status

A Symbol is created by prefixing the name with a colon, like :status.

Explain what a Symbol is in Ruby and why it is immutable.

Think about how Symbols are used as names or keys.

Describe the difference between Symbols and Strings in Ruby.

Consider memory use and mutability.