CODEWITHSUNDEEP
javaregex
beronsus
beronsus

Reputation: 5

restrict number with decimals in between

I am trying to validate whether a number with decimals in between is within the range of 0-255 which allows leading zeroes.

So far I have come up with the regex

^0*([1-9][\.\d]|250)*

and the example that I have tried it on is 63.32.32.250 however it only grabs the 63, and not the rest of the string.

I thought [\.\d] would include all the periods, however it isn't the case.

What am I doing wrong here? Thanks

Upvotes: 0

Views: 87

Answers (4)

Lomas
Lomas

Reputation: 34

Federico Piazza's answer is better but if you want to do it manually I would think about using the split function and checking using ><, e.g...

String[] numbers = "63.32.32.250".split("\\.");
for(String number: numbers){
   -> parse number string to an int
   -> check its in right range just with ><=
}

Hope that helps

Upvotes: 1

Maurice Perry
Maurice Perry

Reputation: 9650

For one group of digits:

^0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])$

For four groups, repeat:

^0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])$

This will capture four groups.

Upvotes: 0

abc123
abc123

Reputation: 18773

Works w/ Flaw

To validate IPv4 addresses you would do something like

^((?:\d{1,3}\.){3}\d{1,3})$

Regular expression visualization

Debuggex Demo

But this has the vital flaw of not checking if the number is between 1-255

Works

^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

Regular expression visualization

Debuggex Demo

Upvotes: 0

Federico Piazza
Federico Piazza

Reputation: 30995

Using a regex for this is not a good idea, you can use InetAddressValidator like this:

InetAddressValidator.getInstance().isValid(YOUR_IP_HERE)

Btw, you can use isValidInet4Address method as well.

Upvotes: 2

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