$i = 0;
where 12 is the size of my array. and i is an index, or is there an al
+ternative?
while($i != 12){
    if($month = $array[i]){
         print "yes it's a month\n";
}
}
[download]

If this is what you want to do then you could do any of these:

for my $i ( 0..11 ) {
   print "yes it's a month\n" if $month eq $monthnames[$i];
}

for my $valid_months ( @monthnames ) {
   print "yes it's a month\n" if $month eq $valid_months;
}

print "Yes it's a month\n" if grep { $_ eq $month } @monthnames;
[download]

You would be better to use a hash as a lookup table like this:

my @months = qw( jan feb mar apr may jun jul aug sep oct nov dec);
my %monthnames;
# create lookup table
$monthnames{$_}++ for @months;
print "Yes it's a month!" if exists $monthnames{$month};
[download]

Warning

In your if($month = $array[i]){ statement you have used = which is the assignment operator when what you really wanted was eq the string equality operator. In perl we have:

$a = 1;      # set $a to 1
$a == 1;     # returns a true value if $a is numerically equal to 1
$a eq 'foo'  # returns a true value if $a is equal to the string value
+ 'foo'
[download]

Using = when you mean == or eq can be very confusing. The assignmet will always succeed so the conditional statement is generally also always true so you have a nasty bug that not only fails to work as expected but also modifies your data. You also need to make sure you use eq rather than == when you want a string comparison:

print "What, a string is numerically == 0?" if 'foo' == 0;
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

Using = when you mean == or eq can be very confusing.

Which is why it is a good idea to put the the constant on left-hand side of a numerical comparison

0 == $foo; # GOOD
0 =  $foo; # BAD

__output__

Can't modify constant item in scalar assignment at - line 2, near "$fo
+o;"
Execution of - aborted due to compilation errors.
[download]

So we get a nice compile-time error if we ever slip up with our numerical comparisons, hurrah!
HTH

_________
broquaint

See perldoc -f grep... My guess is that you want to compare the value in $month to a set of pre-defined values in your array.

my @months=qw(jan feb mar);
my $month="jan";
print "Found" if grep{$month eq $_}@months;
[download]

You could also do:

foreach $month (@array) {
   print "$month\n";
}
[download]

print "yes it's a month\n"
   if grep ($_ eq $month, @array);
[download]

The built-in grep function will return all the matches, and you care if the list is not empty.

More generally, you could use a foreach loop to look at each element in turn.

Use eq for string comparisons. = is assignment, == is numeric comparison.

—John

$i = 0;
where 12 is the size of my array. and i is an index, or is there an al
+ternative?
while($i != 12){
    if($month = $array[i]){
         print "yes it's a month\n";
}
}
[download]

Well first I'll assume the $array[i] is a typo. second you don't seem to be reading through the array. $i is set to 0 and thats not 12 of course so you will loop through the while forever and depending on wether $month contains jan, since $i is the first element in the array it will print "yes it's a month\n" again,and again, and again......etc

you could do it this way though

foreach my $item ($array) {
   print "its the month of $month\n" if ($month eq $array[$i];
}
[download]

I'm not sure if you're trying to find out if each element is a month or looking for one particular month. I just assumned you where looking for a particular month

Update: replaced '=' with correct eq in if statement

jjdraco
learning Perl one statement at a time.

ok.. that's great. one more small question. to read through that array after. can i do:

$i = 0;
where 12 is the size of my array. and i is an index, or is there an al
+ternative?
while($i != 12){
    if($month = $array[i]){
         print "yes it's a month\n";
}
}
[download]

Well there's one immediate error here, which is that you actually mean $montheq $array[i] as firstly these are strings and secondly you don't want to assign to $month!!

However you would do better with code like this:

for $i (0..$#array) { # just in case they change the number of months 
+:)
  next unless ($month eq $array[$i]); # skip if not equal
  print "Yes its a month\n";
  last; # no need to check other months so exit loop
}
[download]

Dingus

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