how to do a simple check

[JS]

I have a program called depstats.pl

which takes some files as input so I run it like:

../deptstats file1 file2 file3

and then loop through all those files using the construct:

while(<>)

How do I check if any files were supplied? Because if I just do :

../depstats.pl

the programs never ends until I CTRL-C it.

Thanks for the help.

JS.

[Bernard El-Hagin]

JS wrote:

> I have a program called depstats.pl
>
> which takes some files as input so I run it like:
>
> ./deptstats file1 file2 file3
>
> and then loop through all those files using the construct:
>
> while(<>)
>
> How do I check if any files were supplied? Because if I just do :
>
> ./depstats.pl

All of the script's arguments are stored in the special array @ARGV, so you
can simply make sure it's not empty. For more


perldoc perlvar

..


--
Cheers,
Bernard
--
echo 42|perl -pe '$#="Just another Perl hacker,"'

[Gunnar Hjalmarsson]

Bernard El-Hagin wrote:

> JS wrote:

>> I have a program called depstats.pl
>>
>> which takes some files as input so I run it like:
>>
>> ./deptstats file1 file2 file3
>>
>> and then loop through all those files using the construct:
>>
>> while(<>)
>>
>> How do I check if any files were supplied?

>
> All of the script's arguments are stored in the special array
> @ARGV, so you can simply make sure it's not empty.

Or maybe:

if (-e $ARGV[0])

--
Gunnar Hjalmarsson
Email: [url]http://www.gunnar.cc/cgi-bin/contact.pl[/url]

[JS]

Gunnar Hjalmarsson wrote:

> Bernard El-Hagin wrote:
>

>> JS wrote:
>>

>>> I have a program called depstats.pl
>>>
>>> which takes some files as input so I run it like:
>>>
>>> ./deptstats file1 file2 file3
>>>
>>> and then loop through all those files using the construct:
>>>
>>> while(<>)
>>>
>>> How do I check if any files were supplied?

>>
>>
>> All of the script's arguments are stored in the special array
>> @ARGV, so you can simply make sure it's not empty.

>
>
> Or maybe:
>
> if (-e $ARGV[0])
>

Thanks for your help,

This worked:

usage() if ! $ARGV[0] ;

[Bernard El-Hagin]

JS wrote:


[...]

> Thanks for your help,
>
> This worked:
>
> usage() if ! $ARGV[0] ;

Or


usage() unless @ARGV;


which seems a bit easier on the eye.


--
Cheers,
Bernard
--
echo 42|perl -pe '$#="Just another Perl hacker,"'

[Tore Aursand]

On Mon, 08 Sep 2003 12:41:04 +0100, JS wrote:

> This worked:
>
> usage() if ! $ARGV[0] ;

There's always more than one way to do it, but please write

usage() unless ( $ARGV[0] );

instead. That 'if !' is ugly, IMO.


--
Tore Aursand <tore@extend.no>

"Whenever I see an old lady slip and fall on a wet sidewalk, my first
instinct is to laugh. But then I think, what if I was an ant, and she
fell on me. Then it wouldn't seem quite so funny." -- Jack Handey

[Helgi Briem]

On Mon, 8 Sep 2003 12:03:21 +0000 (UTC), "Bernard El-Hagin"
<bernard.el-hagin@DODGE_THISlido-tech.net> wrote:

>> Thanks for your help,
>> This worked:
>> usage() if ! $ARGV[0] ;

>
>Or
>
> usage() unless @ARGV;
>
>which seems a bit easier on the eye.

I use:

die $usage if not @ARGV;

but in the end it's a matter of taste.

[Gunnar Hjalmarsson]

JS wrote:

> Gunnar Hjalmarsson wrote:

>>
>> if (-e $ARGV[0])

>
> Thanks for your help,
>
> This worked:
>
> usage() if ! $ARGV[0] ;

Okay. Note that my suggestion includes a check of the file path. Only
you know if such a check would be useful.

--
Gunnar Hjalmarsson
Email: [url]http://www.gunnar.cc/cgi-bin/contact.pl[/url]

[Tad McClellan]

JS <vervoom@hotmail.com> wrote:

> I have a program called depstats.pl
>
> which takes some files as input so I run it like:
>
> ./deptstats file1 file2 file3
>
> and then loop through all those files using the construct:
>
> while(<>)
>
> How do I check if any files were supplied?

die "USAGE: deptstats <files...>\n" unless @ARGV;

> Because if I just do :
>
> ./depstats.pl
>
> the programs never ends until I CTRL-C it.

That is what <> is _supposed_ to do.

It is waiting for you to provide the input via the keyboard (STDIN).

Try typing some input, then mark the end of input with
a CTRL-D (CTRL-Z on Windows).


--
Tad McClellan SGML consulting
[email]tadmc@augustmail.com[/email] Perl programming
Fort Worth, Texas

[Tina Mueller]

JS wrote:

> This worked:

> usage() if ! $ARGV[0] ;

only if the file isn't called "0"
=)

regards, tina
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