Insert, delete

In Ruby, one string can be inserted into another. We use the insert() method and specify the index where to insert.

For insert, the original string is modified. Delete() just removes characters—to remove entire substrings, we use sub() and related methods.

Insert example

We can use the insert() method to place a substring inside an existing string. The original string is modified—no assignment is needed.

# Input string.
value = "socrates"

# Insert string into the input string.
value.insert(3, "k-")
puts value

# Now prepend two characters.
value.insert(0, "??")
puts value
sock-rates
??sock-rates

Delete

This method deletes individual characters, not entire substrings. So if we pass 2 chars like "ET" to it, all the uppercase "E" and "T" chars are erased.

animal = "ELEPHANT"
puts animal

# Delete these 2 characters.
animal.delete!("ET")
puts animal
ELEPHANT
LPHAN

Remove substring

To remove or delete an entire substring from a string, we can invoke the sub() method. Here we replace the substring "country" with an empty string—this removes it.

value = "old country home"
puts value

# Remove substring from string.
value.sub!("country ", "")
puts value
old country home
old home

We used insert and delete. It is important to understand that we can use the sub() method to remove substrings. We replace a substring with an empty string literal.