S2I/S2R

How do these work?

I'm not sure what exactly your asking but:

S2I takes a string and converts it into an integer. So "123" converts to 123.

Same should work with S2R and that a string without a decimal would still work.
So "12" converts to 12.0, "143.4" to 143.4.

I doubt that would suffice I know not what else to say.

Note...

If any invalid chars present 0 (0.0) will return.

no if first char is invalid it will return 0 otherwise it will convert it to the inval char =)

S2I("534z5g4") = 534
(same for S2R)