CareerCup

String ipAdd = "123.123.123.123";
sysout(verifyIpAddress(ipAdd))


boolean verifyIpAddress(String ipAdd) {

String regExp = "[0-2][0-5][0-5]\\.[0-2][0-5][0-5]\\.[0-2][0-5][0-5]\\.[0-2][0-5][0-5]";

return ipAdd.matches(regExp);
}

String regExp = "[0-2][0-5][0-5]\\.[0-2][0-5][0-5]\\.[0-2][0-5][0-5]\\.[0-2][0-5][0-5]";

return ipAdd.matche(regExp);

small correction

String regExp = "[0-2]?[0-5]?[0-5]?\\.[0-2]?[0-5]?[0-5]?\\.[0-2]?[0-5]?[0-5]?\\.[0-2]?[0-5]?[0-5]?";

return ipAdd.matche(regExp);

string pattern = @"\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b"

@"^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.
([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$"; this is a right answer.

the regex above will work for REAL IP addresses ( except for 0.*.*.*) but the question say that the IP is passed as String so 000.000.000.000 will not be matched.
by modifying the above regex you get this: ^([0-9]|0[0-9][0-9]|[0-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|0[0-9][0-9]|[0-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$ which should work for all IP formats (REAL and string ones).

By REAL I mean 000.000.000.000 -> 0.0.0.0