Translation Rules Query

control

Been looking at an article and have a query on the following...

rule 2 /^123/ /456/


rule 3 /^123$/ /456/

It says

rule 2 replaces any number starting with 123 with a 456
rule 3 replaces only the number 123 as the source number with 456

Aren't these both the same thing? I'm not sure on the difference between Rule 1 and Rule 2. Could someone provide an example of these rules being utilized, hopefully seeing it will make it clearer?

Thanks

networker050184

The '^' indicates the begining of the string and the '$' indicates the end. Without the '$' it matches the string and anythng following.

So for example the string '123' would match both, but '1234' would only match the first.