In Ruby, both << and push are methods used to add elements to an array. However, there is a subtle difference between them.
The << method is used to append an element to the end of an array. It modifies the original array and returns the modified array. For example:
arr = [1, 2, 3]
arr << 4
puts arr.inspect # [1, 2, 3, 4]
The push method, on the other hand, can be used to append one or more elements to the end of an array. It modifies the original array and returns the modified array. For example:
arr = [1, 2, 3]
arr.push(4)
puts arr.inspect # [1, 2, 3, 4]
push can also be used to append multiple elements at once, by passing them as arguments:
arr = [1, 2, 3]
arr.push(4, 5, 6)
puts arr.inspect # [1, 2, 3, 4, 5, 6]
In summary, both << and push methods can be used to append elements to an array, but << can only append one element at a time, while push can append one or more elements.