Re: What is the difference?

You'll get different counts on lines that have leading white space. The second program will count an empty field at the beginning of the line. The correct way to do this program is:

#!/bin/perl -w
my $line = 0
while (<>) {
        chomp;
        $line += tr/ \t/./c;
}

print $line, "\n";
[download]

#!/bin/perl -w
my $line = 0
while (<>) {
        $line += tr/ \t\r\n/c;
}

print $line, "\n";
[download]

Comment on Re: What is the difference? Select or Download Code

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Re: Re: What is the difference? by YAFZ (Pilgrim) on Apr 08, 2003 at 15:05 UTC
Thanks for enlightening me! ;-) I prefer your second example. The only problem with that example is that you've forgotten one single slash character at the end of tr: `$line += tr/ \t\r\n/c;` [download] which must be: `$line += tr/ \t\r\n//c;` [download] After fixing that, the sript works cool ;-) I also realized that I can handle the situation using the command line: `$ tr [:space:] -d <ccount.pl \| wc 0 1 69` [download] Now I think that tr (in Perl or in shell) is a better way to get rid of unwanted characters, am I wrong? P.S.: If Thelonious S. Monk programmed (in any language) woe to the ones who could maintain his code ;-)	[reply] [d/l] [select]
Re: Re: Re: What is the difference? by dakkar (Hermit) on Apr 08, 2003 at 18:02 UTC
Your `tr` (the program) example does, indeed, get rid of non-whitespace. The Perl program, howver, does not. What it does is: take all characters but some whitespace (those with ASCII codings 32, 9, 13, 10, in order), changing them with themselves, and returning how many have been (non) changed. The `/c` option complements the first list of `tr///`, while leaving the second list empty makes it equal to the first (in this case, the complemented first). `tr///` in any case returns the number of characters interested by the transliteration. -- dakkar - Mobilis in mobile Most of my code is tested...	[reply]


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