$file=<STDIN>;

my $file = $ARGV[0];

This looks pretty confused to me. You read the filename from STDIN into a package variable called $file (incidently, you don't chomp that value so it still has a newline character on the end). You then ignore that value and create a new, lexical, variable also called $file and into that you copy the value of the first command line argument. You don't say how you call the program, but if you don't give it any command line arguments then that will be 'undef'. You then ignore the package variable (which has the correct value - albeit with an extra newline) and continue to use the lexical value which (probably) contains 'undef'.

So, no, it almost certainly won't do what you want :)

This is a good example of why you should always have use strict in your programs.

You probably want to write that code something like this (untested):

# check to see if you have a command line argument
my $file = $ARGV[0];

# if not, or if it's not an HTML file, then prompt for one
until ($file && ($file =~ /\.html?$/i)) {
  print('Enter an html file (with either a .html or .htm extension): '
+);
  $file=<STDIN>;
  chomp $file;
}

[download]
--
<http://dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

In reply to Re^3: Converting HTML tags into uppercase using Perl by davorg
in thread Converting HTML tags into uppercase using Perl by steve_g50

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.