Reading and writing to files: Debrief Question v2

Merlyn, your code truely is beautiful. It is very simple, and effective.

I am stepping through it to make sure I understand everything. Are the text files read into the arrays in the second and third lines:

my @daily = do { local @ARGV = "daily.txt"; <> };
my @monthly = do { local @ARGV = "monthly.txt"; <> };
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In the fourth line, you don't have to use #@daily (or whatever that operator is that returns the index of the last element)?

Again, wow!

v2: Thank you, Christian. Wow, very beautiful.

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RE: Reading and writing to files: Debrief Question by cmburns (Acolyte) on Aug 09, 2000 at 17:10 UTC
Hi! I'll just answer that question, since merlyn has stated often enough that he doesn't have the time to answer all the "easy" questions. Lines 2 and 3 put those filenames into the `@ARGV` array, which has the same effect as putting those filenames in the commandline (`@ARGV` contains all words in the commandline after the name of the called script.) The operator `<>` reads from all the filenames on the commandline, or from STDIN if there are no filenames on the commandline. So line 2 and 3 actually do read those files into those arrays without needing an `open` statement. Beautiful! In line 4, the array `@daily` is used in a scaler context, since it is compared with a scalar (3). In a scalar context an array returns its length, in this case the number of lines in the file. So you don't need that # operator, although you could use it. I hope I got that all right, I'm pretty new to perl myself. My compliments to merlyn, that is very short yet very readable code. Perl is beautiful! Christian	[reply] [d/l] [select]

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RE: Reading and writing to files: Debrief Question
by cmburns (Acolyte) on Aug 09, 2000 at 17:10 UTC

I'll just answer that question, since merlyn has stated often enough that he doesn't have the time to answer all the "easy" questions.

Lines 2 and 3 put those filenames into the @ARGV array, which has the same effect as putting those filenames in the commandline (@ARGV contains all words in the commandline after the name of the called script.) The operator <> reads from all the filenames on the commandline, or from STDIN if there are no filenames on the commandline. So line 2 and 3 actually do read those files into those arrays without needing an open statement. Beautiful!

In line 4, the array @daily is used in a scaler context, since it is compared with a scalar (3). In a scalar context an array returns its length, in this case the number of lines in the file. So you don't need that # operator, although you could use it.

I hope I got that all right, I'm pretty new to perl myself. My compliments to merlyn, that is very short yet very readable code. Perl is beautiful!

Christian

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