| [reply] |
# Using @x and @y in this.
sub check
{
my ($x, $y) = @_;
return 0 unless $#$x == $#$y;
for (0 .. $#$x)
{
return 0 if $x->[$_] ne $x->[$_] && $x->[$_] != $x->[$_];
}
return 1;
}
The reason for the two comparisons is to make sure that the string comparison doesn't fail with '0' vs '0.0'.
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We are the carpenters and bricklayers of the Information Age. Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement. | [reply]
[d/l] |
What is actually happening when you
if (@sort_savepids ne @sort_livepids )
is that the arrays are getting interpreted in scalar context, which gives you the number of elements in the array.
Any two arrays with a different amount of elements will pass this test.
#!/usr/local/bin/perl
use strict;
my @s1 = qw( a b c );
my @s2 = qw( a b c );
my @s3 = qw( x y z );
print qq{s1 and s2 are equal\n} if ( @s1 eq @s2 );
print qq{s1 and s3 are equal(not really)\n} if ( @s1 eq @s3 );
Both statements will print out.
Wonko
| [reply]
[d/l]
[select] |
As others have said, the test you're doing now only tells you whether the two arrays are the same length.
While not sufficient, it is certainly a good test to do, since if the two arrays are different lengths, they can't possibly be "equal". So in your array-comparing subroutine, that's the first thing you should do.
# pass it two arrays, by reference.
sub arrays_equal
{
my( $ar1, $ar2 ) = @_;
@$ar1 eq @$ar2 or return 0; # different lengths.
# now do member-wise comparison:
for my $i ( 0 .. $#{$ar1} )
{
$ar1->[$i] eq $ar2->[$i] or return 0; # short circuit
}
return 1; # all members compared equal.
}
# call it like so:
if ( ! arrays_equal( \@savedpids, \@livepids ) )
Note that I used string equality. If the arrays are going to contain only numbers, then you'd want to use numeric comparison (==) instead.
As an added syntactic nicety, you can write this subroutine with a prototype, so you don't have to pass the arrays explicitly as references:
sub arrays_equal(\@\@)
{
# everything else is the same
}
# then you can call it like so:
if ( ! arrays_equal( @savedpids, @livepids ) )
If you use the prototype, however, the declaration of the sub must come before the point of first use.
jdporter
The 6th Rule of Perl Club is -- There is no Rule #6. | [reply]
[d/l]
[select] |
If all you need to know is that the two arrays are the same or not, you can use the fairly quick and dirty trick of stringifying them.
my @a1 = (...);
my @a2 = (...);
if ( @a1 == @a2 and do{local $"="\cA"; "@a1"} eq do{local $"="\cA"; "@
+a2"} ) {
# They're the same
}
The caveat is that you must choose a delimiter ("\cA" above) that does not appear in your data. Cntrl-A is a fairly safe bet for either text or numeric data, but if your data could include binary data, there is a small chance of a false positive.
</code>
Examine what is said, not who speaks.
The 7th Rule of perl club is -- pearl clubs are easily damaged. Use a diamond club instead. | [reply]
[d/l] |
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[d/l] |
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