PlexQ PlexQ - 1 month ago 6
Scala Question

How to check to see if a string is a decimal number in Scala

I'm still fairly new to Scala, and I'm discovering new and interesting ways for doing things on an almost daily basis, but they're not always sensible, and sometimes already exist within the language as a construct and I just don't know about them. So, with that preamble, I'm checking to see if a given string is comprised entirely of digits, so I'm doing:

def isAllDigits(x: String) = x.map(Character.isDigit(_)).reduce(_&&_)


is this sensible or just needlessly silly? It there a better way? Is it better just to call x.toInt and catch the exception, or is that less idiomatic? Is there a performance benefit/drawback to either?

Answer

Try this:

def isAllDigits(x: String) = x forall Character.isDigit

forall takes a function (in this case Character.isDigit) that takes an argument that is of the type of the elements of the collection and returns a Boolean; it returns true if the function returns true for all elements in the collection, and false otherwise.

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