Stricter Conversions With Integer And Float

This is based on The Well Grounded Rubyist book, you should definitely buy it

As a ruby programmer you probably have experimented with converting strings to integers:

> "1".to_i
=> 1

Well Ruby has some secrets under their slive with this conversion:

> "hello".to_i
=> 0
> "123hello".to_i
=> 123

As you can see if your string has no reasonable integer equivalent (“hello”) ruby to_i method will always return 0. Otherwise if your string starts with digit but isn’t made up entirely of digits (“123hello”), the nondigit parts are ignored and the conversion is perfomed only on the leading digits. The same thing happen with to_f method:

"hello".to_f
=> 0.0
"1.23hello".to_f
=> 1.23

Sweet huh? But what about if the conversion methods are too flexible for your purposes? What about if you want to avoid those kind of things? Well lucky for you, Ruby has a couple of stricter conversion techniques: Integer and Float

"123abc".to_i
=> "123"
Integer("123abc")
=> ArgumentError: invalid value for Integer(): "123abc"
Float("3")
=> 3.0
Float("-3")
=> -3.0
Float("-3xyz")
ArgumentError: invalid value for Float(): "-3xyz"

So if you want to be strict about what gets converted and what gets rejected, Integer and Float can help you on :)