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RE: Array Question
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From:
Anthony Beaman
Date:
June 25, 2003 11:16
Subject:
RE: Array Question
Message ID:
B46773BE879E6D449E7AA93BEC10A44701E83C79@exchange1.trghd.com
Here's what I got when I ran it:
C:\>perl hello2.pl
Name your friends: Joe Sam Sally
I know .
(good news is that ctrl-z appears to be working again)
When I ran it a second time and skipped a line, it when to the print message after I skipped a line after Sam.
C:\>perl hello2.pl
Name your friends: Joe
Sam
I know .
This is driving me crazy! I can't sleep at night! I need to solve this problem!! I need help!! ARGH!!!!
-----Original Message-----
From: Perry, Alan [mailto:aperry@loislaw.com]
Sent: Wednesday, June 25, 2003 1:38 PM
To: 'beginners@perl.org'
Cc: Anthony Beaman
Subject: RE: Array Question
Oops, the second batch of code has a problem... It should read:
print "Name your friends: ";
$friends = <STDIN>;
chomp($friends);
@names = split(/ +/, <STDIN>);
print "I know $names[1].\n";
Sorry about that...
- Alan
-----Original Message-----
From: Perry, Alan [mailto:aperry@loislaw.com]
Sent: Wednesday, June 25, 2003 12:34
To: 'Anthony Beaman'; beginners@perl.org
Subject: RE: Array Question
Unlike others that are suggesting that you forget about user input, I
thought you might want to see how it can work on Windows. I know that it
would bug me as to how to do this if I were in your position...
print "Name your friends: ";
@names = split(/[ \n]+/, <STDIN>);
print "I know $names[1].\n";
The second line is the "magic". The "split" function takes a string and
splits it up into pieces (a list) which you can put into an array.
The first parameter is a regular expression to search for. Assuming you
have not gotten to regular expressions yet, the parameter I used, "/[
\n]+/", say to the split function to search for one or more spaces or
end-of-line characters and that is what I want to split on.
The second parameter is the string you want to search, in this case, the
input you typed in.
The only problem with the above approach is that you will wind up with an
extra item. Using your names, the array would contain:
$names[0] = "Sam"
$names[1] = "Joe"
$names[2] = "Sally"
$names[3] = ""
The extra null-string at the end is because of the end-of-line character at
the end of the string you typed in. If you wanted to not have that at the
end, you could change your code to something like this:
print "Name your friends: ";
$friends = <STDIN>;
chomp($friends);
@names = split(/[ +/, <STDIN>);
print "I know $names[1].\n";
The "chomp" line above removes the end-of-line character, so you will only
have three elements in your array.
There are a lot of other tricks you can do, but I have probably confused you
enough for now... :)
- Alan
-----Original Message-----
From: Anthony Beaman [mailto:AnthonyBeaman@trginc.com]
Sent: Wednesday, June 25, 2003 11:01
To: beginners@perl.org
Subject: RE: Array Question
The plot thickens! I can get it to work if I have a data in the array, such
as my script below:
print "Here are your friends: ";
@friends = qw (Sam Joe Sally);
print "@friends\n";
print "I know $friends[1]";
I still can't grab the element of an array that requests user input though.
-----Original Message-----
From: Derek Byrne [mailto:Derek.Byrne@meteor.ie]
Sent: Wednesday, June 25, 2003 8:33 AM
To: beginners@perl.org
Subject: RE: Array Question
Hi Anthony,
grabbed this from O'Reilly's Learning Perl :
@rocks = qw/ bedrock slate lava /;
foreach $rock (@rocks) {
$rock = "\t$rock"; # put a tab in front of
each element of
@rocks
$rock .= "\n"; # put a newline on the end
of each
}
print "The rocks are:\n", @rocks; # Each one is indented, on
its own line
Still learning how to grab input from user via chomp, but
this should help
you work out how to print out all entries in an array using
the foreach
thingy :o)
DerekB
-----Original Message-----
From: Anthony Beaman [mailto:AnthonyBeaman@trginc.com]
Sent: 25 June 2003 13:24
To: beginners@perl.org
Subject: Array Question
Hi! I'm still wallowing in Chapter 3 (Arrays. Why can't I
get it?!?!?!?
ARGH!!!!!) of Learning Perl on Win32 Systems. I'm trying to
create an
exercise but I'm not getting the results that I want. Here's
what I'm trying
to do:
I'm asking for a list of names:
print "Name your friends: ";
@names = <STDIN>;
Then I want to pretend that I know the one of the friends.
In this case,
I'll choose the 2nd one and here's where I'm not getting
what I want:
print "I know $names[1].\n";
The output shows "I know ."
Isn't "$names[whatever]" what I'm supposed to use to get an
element of the
array? I've tried this with numbers and have gotten the same
results. What
am I doing wrong? Thanks! :-)
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