String slicing and indexing in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does string indexing mean in Ruby?

String indexing means accessing a single character in a string by its position number, starting from 0 for the first character.

beginner

How do you get the first 5 characters of a string in Ruby?

You can use slicing like this: str[0, 5] which means start at index 0 and take 5 characters.

intermediate

What does negative indexing do in Ruby strings?

Negative indexing counts from the end of the string. For example, str[-1] gives the last character.

beginner

How to slice a string from index 2 to index 6 in Ruby?

Use str[2..6] which includes characters from index 2 up to 6, inclusive.

intermediate

What happens if you try to slice beyond the string length in Ruby?

Ruby returns as many characters as possible without error. For example, str[0, 100] returns the whole string if it is shorter than 100 characters.

What does str[3] return in Ruby?

A The first 3 characters

B The last 3 characters

C The character at index 3

D An error

str[3] returns the single character at position 3 (fourth character) in the string.

How do you get the last character of a string str in Ruby?

A str[-1]

B str[0]

C str[1]

D str[last]

Negative index -1 accesses the last character in Ruby strings.

What does str[1..4] return?

A An error

B Characters from index 1 to 3

C Characters from index 0 to 4

D Characters from index 1 to 4 inclusive

The range 1..4 includes both ends, so characters at indexes 1, 2, 3, and 4 are returned.

What happens if you do str[5, 10] but the string length is 8?

A Returns characters from index 5 to the end

B Returns an error

C Returns nil

D Returns the whole string

Ruby returns characters from index 5 to the end without error, even if 10 characters are requested.

Which of these is NOT a valid way to slice a string in Ruby?

A str[0, 3]

B str(1..4)

C str[-3..-1]

D str[2..5]

str(1..4) is not valid syntax for slicing strings in Ruby.

Explain how to access a single character and a substring in Ruby strings using indexing and slicing.

Think about how you get one letter vs. a group of letters.

Describe how negative indexing works in Ruby strings and give an example.

Negative numbers start counting backwards from the last character.