Hi, most of you People would have learned about Perl from Books and PDFs. So here we directly dive into the world of programming. Lets start with a very easy task.
if ($ip =~ m/^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})$/)
Try giving IP as 320.1.256.700
if ($ip =~ m/^((\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3}))$/)
How to Validate an IP address?
I am sure that most of you people would have got this as your assignement or as a question in your Interview.
We can give a simple regular expression as solution for this.
my $ip; #ip address
$ip = <STDIN>;
chomp($ip);
if ($ip =~ m/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/)
{
print "Valid IP\n";
}
else
{
print "Invalid IP\n";
}
Try this code for various possible value. It will work for most of the cases.
Give this as input - 1.2.3.4.5
Is this valid IP? - No!!!
But the script will an output "Valid IP".
Now lets modify the code.
my $ip; #ip address
$ip = <STDIN>;
chomp($ip);
{
print "Valid IP\n";
}
else
{
print "Invalid IP\n";
}
Now give input as 1.2.3.4.5
The output must be Invalid IP
Try giving IP as 320.1.256.700
What is the output?
Valid IP right!!! But this is not a valid IP. We need to put one more check. Because each node in IP will be from 0 to 255.
my $ip; #ip address
$ip = <STDIN>;
chomp($ip);
{
if ((($1 > -1) && ($1 < 256)) && (($2 > -1) && ($2 < 256)) && ( ($3 > -1) && ($3 < 256)) && (($4 > -1) && ($4 < 256)))
{
print "Valid IP\n";
}
else
{
print "Invalid IP\n";
}
}
else
{
print "Invalid IP\n";
}
Now every cases will be working fine. Try yourself now. :)
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