How to replace the last occurrence of a substring in ruby?

Question

I want to replace the last occurrence of a substring in Ruby. What\'s the easiest way? For example, in abc123abc123, I want to replace the last abc

Answer 1

"abc123abc123".gsub(/(.*(abc.*)*)(abc)(.*)/, '\1ABC\4')
#=> "abc123ABC123"

But probably there is a better way...

Edit:

...which Chris kindly provided in the comment below.

So, as * is a greedy operator, the following is enough:

"abc123abc123".gsub(/(.*)(abc)(.*)/, '\1ABC\3')
#=> "abc123ABC123"

Edit2:

There is also a solution which neatly illustrates parallel array assignment in Ruby:

*a, b = "abc123abc123".split('abc', -1)
a.join('abc')+'ABC'+b
#=> "abc123ABC123"