matching IP address string

[merc58]

I want to match an IP address in a string and store in a variable thus :-

$string = "192.168.2.1";

while (<STDIN>) {

$_ = /\d{1,3}\.{3}\d{1,3}/;
$ip = $1;

}
is this correct?

 

[travs69]

if ($_ =~ /\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}/) {
print "$1\n";
}


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those who say it cannot be done are usually interrupted by someone else doing it; Give the wrong symptoms, get the wrong solutions;

 

[prex1]

I would prefer

if(/\b(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\b/) {
  print "$1\n";
}

Franco

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[learingperl01]

One thing to keep in mind is that the regex above will also match non IP addresses, if you need to validate that the data you are working with is an valid IP you will need to modify your regex.

 

[rvBasic]

Matching an IP address is another good example of a trade-off between regex complexity and exactness. \b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b will match any IP address just fine, but will also match 999.999.999.999 as if it were a valid IP address. Whether this is a problem depends on the files or data you intend to apply the regex to. To restrict all 4 numbers in the IP address to 0..255, you can use this complex beast: \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 (everything on a single line). The long regex stores each of the 4 numbers of the IP address into a capturing group. You can use these groups to further process the IP number.

If you don't need access to the individual numbers, you can shorten the regex with a quantifier to: \b(??: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]?)\b . Similarly, you can shorten the quick regex to \b(?:\d{1,3}\.){3}\d{1,3}\b


From

http://www.regular-expressions.info/examples.html

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