Reputation:

Regex to match these number rules

In Java, I'm currently using

str.matches("\\d")

but its only matching a single number.

I need to match ints and doubles, e.g. :

"1"
"1337"
".1"
"13.7"

Any help would be awesome.

Upvotes: 3

Answers (6)

MahdeTo

Reputation: 11184

((\+|-)?(\d+(\.\d+)?|\.\d+))

This would match positive and negative ints, doubles that start with a digit, and doubles start with a dot

Upvotes: 2

rayfranco

Reputation: 3690

I think this regular expression can help you

\\d*\\.?\\d+

Upvotes: 5

tchrist

Reputation: 80384

This will match any real number that the Java compiler will recognize. To do this, it also handles things like signed numbers and exponentials. It’s in Pattern.COMMENTS mode because I think anything else is barbaric.

(?xi)                      # the /i is for the exponent
(?:[+-]?)                  # the sign is optional
(?:(?=[.]?[0123456789])
   (?:[0123456789]*)
   (?:(?:[.])
      (?:[0123456789]{0,})
   ) ?
)
# this is where the exponent starts, if you want it
(?:(?:[E])
   (?:(?:[+-]?)
      (?:[0123456789]+)
   ) 
   |
)

Upvotes: 1