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Mark Day 09-28-2004 07:56 AM

printing array problem
 
Any tips on what I'm doing wrong here appreciated.

I'm using perl version 5.6.1 on Win98,

and this test script i've written, I was hoping would print each element
of this array, on a new line, then print the array again in reverse order.

What actually output's is the same array twice with all elements printed
on the same line.

What is wrong with my attempt to reverse the array, adn why does each
scalar not print on a new line?

thanks.

--code snippet---

#!C:\perl\bin\perl

@array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

foreach (@array)

{

print $_;

print "\n";

}

@array = reverse @array;

foreach (@array) {

print $_;

print "\n";

}


Mark Clements 09-28-2004 08:06 AM

Re: printing array problem
 
Mark Day wrote:
> Any tips on what I'm doing wrong here appreciated.
>
> I'm using perl version 5.6.1 on Win98,
>
> and this test script i've written, I was hoping would print each element
> of this array, on a new line, then print the array again in reverse order.
>
> What actually output's is the same array twice with all elements printed
> on the same line.
>
> What is wrong with my attempt to reverse the array, adn why does each
> scalar not print on a new line?
>
> thanks.
>
> --code snippet---
>
> #!C:\perl\bin\perl
>
> @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);


qq() gives you an interpolated string - man perlop. what you are
effectively doing here is

@array = "1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen";

which will set $array[0] to "1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen"
and leave the rest of the array empty.

you probably mean

my @array = qw(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

though that will give you "baker's" and "dozen" as separate array elements.

You can also skip the

@array = reverse @array

step

ie

foreach( reverse @array){

....

Mark

Mark Day 09-28-2004 08:09 AM

Re: printing array problem
 


Mark Clements wrote:

> qq() gives you an interpolated string - man perlop. what you are
> effectively doing here is
>
> @array = "1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen";
>
> which will set $array[0] to "1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen"
> and leave the rest of the array empty.
>
> you probably mean
>
> my @array = qw(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);
> though that will give you "baker's" and "dozen" as separate array elements.
>
> You can also skip the
>
> @array = reverse @array
>
> step
>
> ie
>
> foreach( reverse @array){
>
> ...
>
> Mark



Great! thanks.


Anno Siegel 09-28-2004 08:09 AM

Re: printing array problem
 
Mark Day <soundz@techie.com> wrote in comp.lang.perl.misc:
> Any tips on what I'm doing wrong here appreciated.
>
> I'm using perl version 5.6.1 on Win98,
>
> and this test script i've written, I was hoping would print each element
> of this array, on a new line, then print the array again in reverse order.
>
> What actually output's is the same array twice with all elements printed
> on the same line.
>
> What is wrong with my attempt to reverse the array, adn why does each
> scalar not print on a new line?
>
> thanks.
>
> --code snippet---
>
> #!C:\perl\bin\perl
>
> @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);


[snip]

Look up what qq() does. I guess you meant to say qw() instead.

Anno

Graham Wood 09-28-2004 08:11 AM

Re: printing array problem
 
Mark Day wrote:
>
> hoping would print each element
> of this array, on a new line, then print the array again in reverse order.
>
> What is wrong with my attempt to reverse the array, adn why does each
> scalar not print on a new line?
>
>
> #!C:\perl\bin\perl
>
> @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);


Your problem is that you're using qq which will surround the contents of
the parenthesis with double quotes rather than qw which will surround
each word in the parenthesis with double quotes. You are basically
creating and array with one element in it: "1 2 3 4 5 6 7 8 9 10 11 12
baker's dozen" and reversing this then gives you the same single element
in reverse order.

Replace qq with qw and see what happens.

Graham

>
> foreach (@array)
>
> {
>
> print $_;
>
> print "\n";
>
> }
>
> @array = reverse @array;
>
> foreach (@array) {
>
> print $_;
>
> print "\n";
>
> }


Anno Siegel 09-28-2004 08:25 AM

Re: printing array problem
 
Graham Wood <Graham.T.Wood@oracle.com> wrote in comp.lang.perl.misc:
> Mark Day wrote:


[...]

> > @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

>
> Your problem is that you're using qq which will surround the contents of
> the parenthesis with double quotes rather than qw which will surround
> each word in the parenthesis with double quotes.


That is wrong. "qw()" surrounds the whole string with single quotes,
then splits the result on whitespace.

Anno

Anno Siegel 09-28-2004 08:37 AM

Re: printing array problem
 
Anno Siegel <anno4000@lublin.zrz.tu-berlin.de> wrote in comp.lang.perl.misc:
> Graham Wood <Graham.T.Wood@oracle.com> wrote in comp.lang.perl.misc:
> > Mark Day wrote:

>
> [...]
>
> > > @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

> >
> > Your problem is that you're using qq which will surround the contents of
> > the parenthesis with double quotes rather than qw which will surround
> > each word in the parenthesis with double quotes.

>
> That is wrong. "qw()" interprets the whole string in single-quote
> style, then splits the result on whitespace.
>
> Anno




Anno Siegel 09-28-2004 08:47 AM

Re: printing array problem
 
Graham Wood <Graham.T.Wood@oracle.com> wrote in comp.lang.perl.misc:
> Mark Day wrote:


[...]

> > @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

>
> Your problem is that you're using qq which will surround the contents of
> the parenthesis with double quotes rather than qw which will surround
> each word in the parenthesis with double quotes.


That is wrong. "qw()" treats the whole string as single quoted,
then splits the result on whitespace.

Anno


Graham Wood 09-28-2004 10:32 AM

Re: printing array problem
 
Anno Siegel wrote:
>
> Graham Wood <Graham.T.Wood@oracle.com> wrote in comp.lang.perl.misc:
> > Mark Day wrote:

>
> [...]
>
> > > @array = qq(1 2 3 4 5 6 7 8 9 10 11 12 baker's dozen);

> >
> > Your problem is that you're using qq which will surround the contents of
> > the parenthesis with double quotes rather than qw which will surround
> > each word in the parenthesis with double quotes.

>
> That is wrong. "qw()" treats the whole string as single quoted,
> then splits the result on whitespace.



Oh. Thanks

Graham

>
> Anno



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