How to remove a variable length of the word from the string?

[shalini jain]

Hi all,

I dont know much of PERL so i m facing a problem in trying to remove the variable length of word from the string. I have written a code for it. Please guide me whether i will get the desired results or not?
Let me make you all clear my taking following example:

$string='//abc1234/default/folder1/images';

Now i want to remove "//abc1234" from this string. The length of this part of the string may vary that is it may be "//abcd1234" or "abc".
The key in this string is "default" which will always be there.
and i also want both the variable part and non variable to be stored in some variable.

This is the code that i have written:

my $string = '//abc1234/default/folder1/images';
my $check = 'default/';
my $index = index $string, $check;
$index = $index - 1;
 
my $address = substr $string, 0, $index; 
my $fragment = substr $string, $index; 
 

(I am expecting that $address will give me "//abc1234", the variable part.
and $fragment will give me "/default/folder1/images").

Please review the above code and tell me if i m correct or not.
If i m wrong, then how can i get the desired output? Please help me.

[miller]

Greetings,

Your code is correct. However, making some slight modifications gives me this:

my $string = '//abc1234/default/folder1/images';
my $check = '/default';
my $index = index $string, $check;
 
my $address = substr $string, 0, $index;
my $fragment = substr $string, $index;
 
print "$address\n";
print "$fragment\n";
 

Output is:

>perl scratch.pl
//abc1234
/default/folder1/images
 

Also, if you want to use a regular expression, this would also work:

my $string = '//abc1234/default/folder1/images';
my $check = '/default';
 
$string =~ /(.*?)(\Q$check\E.*)/;
 
my $address = $1;
my $fragment = $2;
 

I would suggest that you add error checking to your logic though. It's pretty easy to do in both of these cases.

- Miller

[shalini jain]

Thanks a lot Miller for your reply.

But i was unable to understand your second point about adding error logic. Will you please elaborate more on this point by giving example?

I mean are you saying that: I check if I am getting "/default" in my string or not and then apply the above logic..

[miller]

What if there is no such match in your string? In the case of the index function, -1 will be returned. In the case of the regular expression, false will be returned.

I don't know what your data is like, but it's always safer to add error checking to your parsing just in case your data is not as you expect.

- Miller