output results

[oysters2000]

I don’t understand how they get their answer as the code is not that clear.
Could some one could explain line by line how they get their answer, I would really appreciate it.




sub returnValues {
my($target, @values) = @_;
my(@results);
foreach(@values) {
$_ > $target ? push(@results, “$_\n”) : “”;
}
return @results;
}

using this subroutine, what is the output of the following perl statements?

@myNumList = (33, 35, 67, 11, 78, 99, 23, 55);
print returnValues(50, @myNumList);

 

[ishnid]

Which bit don't you understand?

 

[rharsh]

Here's a quick and dirty explanation. Like ishnid said, which bit don't you understand?

I rewrote the '$_ ? stuff : ""' statement for clarity. Essentially all it does is checks whether the current $_ is greater than $target and, if yes, (does whatever is after the [red]?[/red]) adds it to the @results, if not (and this part is unnecessary because it does nothing - but it's the code after the [red]:[/red]) does nothing. (In fact you'll get a warning similar to "useless use of constant in void context." if you run the code you posted.)

sub returnValues {
    my($target, @values) = @_;  # Declares $target and @values. Copies first
                                # argument into $target, remaining go to @values
    my(@results);               # Declares @results
    foreach(@values) {          # foreach item in @values (assigned to $_)
        #$_ > $target ? push(@results, "$_\n") : "";    # Rewritten below
        if ($_ > $target) {
            push(@results, "$_\n"); # Adds current value of $_ and a new line
                                    # character to @results
        }
    }
    return @results;            # Returns contents of @results;
}

my @myNumList = (33, 35, 67, 11, 78, 99, 23, 55);   # Creates @myNumList and
                                                    # populates it with values
print returnValues(50, @myNumList);                 # prints results of &returnValues

 

[mikevh]

rharsh's explanation is fine, but the wrapping of the commented line-ends make it a little hard to read, for me at least. Thought you might find the following a little more readable:

[b]Code:[/b]
 1. sub returnValues {
 2.     my($target, @values) = @_;
 3.     my(@results);
 4.     foreach(@values) {
 5.         if ($_ > $target) {
 6.             push(@results, "$_\n");
 7.         }
 8.     }
 9.     return @results;
10. }
11. my @myNumList = (33, 35, 67, 11, 78, 99, 23, 55);
12. print returnValues(50, @myNumList);

[b]Comments:[/b]
 2. Declares $target and @values. Copies first argument
    into $target, remaining go to @values
 3. Declares @results
 4. foreach item in @values (assigned to $_)
 6. Adds current value of $_ and a new line character to
    @results
 9. Returns contents of @results;
11. Creates @myNumList and populates it with values
12. prints results of &returnValues

I produced the above output from rharsh's post with the following script. (Okay, I did edit a little bit.):

#!perl
use strict;
use warnings;

my (@code, @comments);
my $lineno = 0;
my $cstr = '';

while (<>) {
   chomp;
   /^\s*$/ && next;
   my ($code, $comment) = map {s/\s+$//; $_} split /#\s*/;
   if ($code) {
       if ($cstr) {
           push(@comments, [$lineno, $cstr]);
           $cstr = '';
       }
       $lineno++;
       push(@code, [$lineno, $code]);
   } 
   if ($comment) {
       $cstr .= $cstr? ' ' . $comment: $comment;
   }
}
push(@comments, [$lineno, $cstr]) if $cstr;

my $str = "Code";
for (\@code, \@comments) {
    printem($str, $_);
    print "\n";
    $str = "Comments"
}

sub printem {
    my ($str, $arr) = @_;
    print "$str:\n";
    printf "%2d. %s\n", @$_ for @$arr;
}

rharsh, thanks for pointing out that
$_ > $target ? push(@results, “$_\n”) : “”;
is a terrible way to write that.

HTH

 

[mikevh]

I think this is a little bit too much like asking us to do your homework for you. Why don't you tell us what you think the answers are?

 

[mikevh]

OP posted same question in this thread: thread219-1007681.
Don't waste your time with this one.