What is the shortest way to insert 2 dashes into this string with ruby?

Question

Here's the string: 04046955104021109

I need it to be formatted like so: 040469551-0402-1109

What's the shortest/most efficient way to do that with ruby?

Answer 1

Two simple inserts will work just fine:

example_string.insert(-9, '-').insert(-5, '-')

The negative numbers mean that you are counting from the end of the string. You could also count from the beginning if you'd like:

example_string.insert(9, '-').insert(14, '-')