confused - if function - PERL Beginners

[Mike]

I am getting a bit confused here, if I uncomment out the print statement
within the if block $date1 prints, however the $date1 after the if block
doesn't

if ($date eq ''){
my $date1=localtime;
#print $date1;
}
else {
my $date1=~$date;
};
print $date1;

any ideas

[James]

On Apr 27, 2004, at 5:39 AM, mike wrote:
 

my(...) scopes a variable locally, which usually means it ceases to
exist at the next }, or end of the block. If you need the same
variable through and outside a block, you have to declare it outside:

my $date1;
if ($date eq '') { $date1 = localtime; }
else { $date1 = $date; } # not what you had, but I bet it's what you
meant
print "$date1\n";

While we're talking, you should look into adding the following two
lines to the top of all your code:

use strict;
use warnings;

This would have kept the code you posted from compiling and it would
have told you why. Build good habits.

Good luck.

James

[William]

It works, but it prints nothing. You are basically dealing with 3 variable
here. the first 2 $date1 goes out of scope outside if {} else {}.

Simply move your declaration out of the if statement. That is:


my $date1 = "";


if ( your condition){
$date1=localtime;
}
else {
..
..

};

print $date1;


__________________

William Ampeh (x3939)
Federal Reserve Board



mike
<mikebristolrec To: org
cc.co.uk> cc:
Subject: confused - if function
04/27/2004 06:39
AM






I am getting a bit confused here, if I uncomment out the print statement
within the if block $date1 prints, however the $date1 after the if block
doesn't

if ($date eq ''){
my $date1=localtime;
#print $date1;
}
else {
my $date1=~$date;
};
print $date1;

any ideas

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[Jeff]

You are absolutely correct, that the my is included inside the { } block. But that is exactly where the confusion sets in, having had this problem when I started coding in perl. The { } are required when using an if/else construct -- part of the syntax to perform this function. Whereas a block is *optional*, like in C/C++.

So yes, technically, any code inside a { } will be a block and the 'my' looses scope. But I totally understand the original poster's confusion!


-JW



James Edward Gray II <net> wrote:
On Apr 27, 2004, at 5:39 AM, mike wrote:
 

my(...) scopes a variable locally, which usually means it ceases to
exist at the next }, or end of the block. If you need the same
variable through and outside a block, you have to declare it outside:

my $date1;
if ($date eq '') { $date1 = localtime; }
else { $date1 = $date; } # not what you had, but I bet it's what you
meant
print "$date1\n";

While we're talking, you should look into adding the following two
lines to the top of all your code:

use strict;
use warnings;

This would have kept the code you posted from compiling and it would
have told you why. Build good habits.

Good luck.

James


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For additional commands, e-mail: org




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