Regular expressions

[Anonymous Monk]

Hi monks

I have another question regarding pattern matching.

I have a piece of html that I need to search through. The html looks like this:

<!-- Start_of_revision-->
revision1
<!-- End_of_revision-->
 
<!-- Start_of_revision-->
revision2
<!-- End_of_revision-->

<!-- Start_of_revision-->
revision3
<!-- End_of_revision-->

What I need to do is find the three revisions between <!-- Start_of_revision--> and <!-- End_of_revision-->.

I am using the following bit of code to do this, but I am only printing "revision1" and not the second two:

my $file = $foo_bar_file;
    open (FILE,"<$file") || die $!;
    read FILE, my $text, -s $file;
    close(FILE);
    if($text =~ /<!--Start_of_revision-->(.*?)<!-- End_of_revision-->/
+sg)
    {
    print $1;
    }

I am slurping in the whole file, I am using .*? (i.e. non greedy), and I'm using the s and g modifiers. I thought that this would be enough to find all three occurrences of anything between <!-- Start_of_revision--> and <!-- End_of_revision-->, so what am I doing wrong??

Thanks in advance,

C J

[rev_1318]

if will only look for the first occurrence. You're looking for while...

[Anonymous Monk]

<sheepish>
Of course. Thanks!
</sheepish>
C J

[GrandFather]

Two problems:

• Missing space in <!--Start_of_revision-->
• if rather than while

  A working version of your code in a form that is better for stand alone testing is:

  Read more... The code (683 Bytes)
  Read more... Output (239 Bytes)

[ikegami]

That's an aweful way of reading a file. It means every line must be pushed onto the stack. The OP's method was better, and the following is even better because it avoids a call to stat and works will all kinds of IO handles:

my $text; { local $/; $text = <DATA>; }

Visually, I prefer
my $text = do { local $/; <DATA> };
but I think I determined the above is equivalent to
my $text; { local $/; my $temp = <DATA>; $text = $temp; }

[GrandFather]

The reason I am a monk is to learn from the masters. I keep forgetting about $/! I hope I have learned :). Thank you.

[tphyahoo]

You could also use File::Slurp. Not sure if it's advantageous speed or algorithmwise; the documentation claims it does. But I just like it for readability.