not null cheking of an argument in perl

ammu · #1 (**permalink**) 06-05-2007

Hi,

I have to check whether an argument say $ARGV[1] is not null in an if operator. Please let me know the operator. It would be great if you write a psuedo code.

Thanks in advance
Ammu

vino · #2 (**permalink**) 06-05-2007

A couple of ways to do this.

Code:

VAR=
if [ -z "${VAR}" ] ; then
  echo "VAR contains nothing"
fi

or

Code:

VAR=
if [ x"${VAR}" = x ] ; then
  echo "VAR contains nothing"
fi

edit: My bad. I did not notice that you asked for it in perl

ammu · #3 (**permalink**) 06-05-2007

Hi Vino,

Thanks for replying. I just want to know whether -z will work in perl script.

if it works then the code should be something like

if ( -z "$ARGV[2]" ) then.....fi

Please correct me if I am wrong

Thanks
Ammu

aigles · #4 (**permalink**) 06-05-2007

Code:

if ($ARGV[1] eq "") { print "Empty\n";}

Jean-Pierre.

matrixmadhan · #5 (**permalink**) 06-05-2007

Quote:

Originally Posted by ammu

Hi Vino,

Thanks for replying. I just want to know whether -z will work in perl script.

if it works then the code should be something like

if ( -z "$ARGV[2]" ) then.....fi

Please correct me if I am wrong

Thanks
Ammu

for not null checking in perl,

how about using

Code:

if ( ! defined $var  ) {
  print "not defined\n";
}
else {
  print "defined\n";
}

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