I can't find a way to check if a Str is a number or digit. For example, let's say I wanted to know if "23" is a number, How would I do that? Or if "abc" was a number.

Strange, there is Str.isAlpha() and Str.isAlphaNum() but no Str.isNum().

So it seems there's no direct method but you could use:

"abc".all { it.isDigit }  // --> false
"123".all { it.isDigit }  // --> true

Thanks, that solved my problem.

Yes, that might solve the problem, but it's not a general solution. Consider this:

"123".all { it.isDigit }  // --> true
"123.4".all { it.isDigit }  // --> false

This can be solved like this:

"123.4q".toDecimal(false) != null ? true : false // returns false
"123.4".toDecimal(false) != null ? true : false // returns true

or if you want return value immediately, use this:

"123.4q".toDecimal(false) ?: -1 // returns -1
"123.4".toDecimal(false) ?: -1 // returns 123.4

That will not work for negative numbers, or numbers with a decimal point:

"abc".toDecimal(false) != null // -->true

"-22".toDecimal(false) != null // -->false

"1.12".toDecimal(false) != null // --> true

EDIT - rasa - you got there before me!

One change, I don't think you need the ternary conditional operator - != returns true or false as needed.

Tom

Yes. Ternary operator is not needed. But, you are wrong about negative numbers and numbers with decimal point. It will work for them either:

"abc".toDecimal(false) != null  // --> false
"-22".toDecimal(false) != null  // --> true
"1.12".toDecimal(false) != null // --> true

or this may be easier to read:

"abc".toDecimal(false) == null  // --> true
"-22".toDecimal(false) == null  // --> false
"1.12".toDecimal(false) == null // --> false

Agreed - I meant the OTHER method does not work for these!