Perl: What's this mean? (Code sample)

Benr · 10-20-2004, 03:42 PM

I got this example Perl code off of oopweb.com but when I try and run it I get an error:

"Number found where operator expected at ./testperl line 8, near "1"
(Missing semicolon on previous line?)
syntax error at ./testperl line 8, near "1"
Execution of ./testperl aborted due to compilation errors."

Here is the code.

Code:

print "Please enter your name:\n";
$name = <>;
chomp($name);
$fl = lc(substr($name
0
1));
if (($fl eq "a")||($fl eq "b")||($fl eq "c"))
{
    print "Your name starts with one of the " .
        "first three letters of the ABC.\n";
}
else
{
    print "Your name does not start with one of the " .
        "first three letters of the ABC.\n";
}

Also, I've been looking at the perldoc for lc and for subsrt but I don't quite understand what is going on with them. And I definitely don't understand what they are doing together in the above example.

dannyp · 10-20-2004, 04:27 PM

lc changes the letters to lowercase.

substr creates another substring of the $name variable with an offset and the length of characters from the offset.

so the substr expression used in this starts at offset 0 which is in front of the 1st letter and takes 1 which is the 1st letter.

Sorry if I confused you, in short the expression takes the first letter of the name that is typed in, turns it to lowercase and checks to see if it is a,b, or c.

Benr · 10-20-2004, 04:52 PM

Thanks for explaining it. heh Unfortunately it looks like it won't work for what I'm trying to do.

Basically I'm trying to search through an array using input from the user. So it would be like, take first search term, search array, store answer, take second term, search array, store answer, take third search term, search array, store answer, display matches.

I found this code that says it's for searching array's but I don't fully understand this one either

Code:

sub search {
  my ($foo, $test) = @_;
  for my $bar (@$foo) {
    if ($foo eq $test) {
      return 1;
    } 
  } 
  return 0;
} 

$found = search(\@array, $string);

Chrax · 10-20-2004, 09:14 PM

my suggestion:

Code:

@query;
@arraytosearch;
@matches;

foreach (<>){
    push @query, $_;
}
chomp @query;

for (@query){
    for (@arraytosearch){
        if ($_ eq $query){
            push @matches, $_;
}}}

print "@matches\n";

Edit this to suit your needs, but it's the jist of what you asked for

What that one will do is search @array for $string and just return a true/false (1 or 0). That seems like it would be slow (code-wise, I don't know about compiler) to check through many search terms. Personally, I tend to side for scalability over speed.

Benr · 10-21-2004, 09:54 PM

Hey, thanks for the reply. I've got my script to about where I want it, I can't seem to figure out how to make perl stop taking input though. heh

How can I tell perl that a blank return or something like it that that means stop and move on to the next part?

Cedrik · 10-23-2004, 07:20 AM

From the Chrax's code, try change :

Code:

foreach (<> ){
    push @query, $_;
}

to :

Code:

while (<> ) {
    last if /^$/;
    push @query, $_;
}

So input stop when it meet a blank line ( /^$/ )