Select Code to Download

s/\.\K[^.]*$/txt/;

Compiling REx "(?<=[.])[^.]*$"
Final program:
...
   7 <xyz.foo> <>            | 19:  EOL(20)
   7 <xyz.foo> <>            | 20:  END(0)
Match successful!

Compiling REx "\.\K[^.]*$"
Final program:
...
   7 <xyz.foo> <>            | 16:    EOL(17)
   7 <xyz.foo> <>            | 17:    END(0)
Match successful!