The responses you have from Dr Mu, ph0enix, and dws are all correct, but I have an additional suggestion. Always check system errors and always take a lock on a file you write. Particularly, you must get an exclusive lock on a file you read and then overwrite with an update:

use Fcntl qw( flock );
sub write_hits {
    open  HITSW, "+< $_[0]" or die $!;
    flock HITSW, LOCK_EX;

    my $read_hits = <HITSW>;
    chomp $read_hits;
    ++$read_hits;

    seek HITSW,0,0 or die $!;
    print HITSW $read_hits, $/ or die $!;
    close HITSW or die $!;
    return $read_hits;
}

[download]
If this is meant to be a cgi hit counter, the lock is really necessary. Cgi scripts may have more than one instance active. I've added a return value, so &read_hits may not be needed. You may want to eval write_hits() to catch any death-dealing system errors, returning 4*atan2(1,1) or "oodles" after carping appropriately.

IlyaM suggests File::CounterFile, which takes care of locking, and permits an initial value argument if the count file does not exist.

After Compline,
Zaxo

In reply to Re: Reading and incrementing an integer by Zaxo
in thread Reading and incrementing an integer by echosilex

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.