Looking on the Perl cookbook on page 152 there is a script that looks
like the one below. I am in need of something similar, however when I
try to even use the example given it errors on the while (<>). I have
4 perl boooks and I still can find out what is wrong w/ the syntax.
Hopefully this is a quickie. Anyone??

 
#!/usr/bin/perl -w


%father = (
Cain  => "Adam",
Abel  => "Adam",
Seth  => "Adam",
Enoch => "Cain",
Irad  => "Enoch",
Mahujael  => "Irad",
Methusael => "Mehujael",
Lamech    => "Methusael",
Jabal => "Lamech",
Jubal => "Lamech",
Tubalcain => "Lamech",
Enos  => "Seth" );


 while ( ($k,$v) = each %father) {
push( @{$children{$v} }, $k );
}

#$_ = ',';
while (<>) {
chomp;
if ($children{$_}) {
@children=@{$children{$_}};
} else {
@children = "nobody";
}
print "$_ begat @children.\n";
}

---

Request for Question Clarification by googleexpert-ga on 04 Mar 2003 07:31 PST

I have a problem with the while(<>) statement, I think that's used for
filehandling.  anyway, I modified two lines of code and received the
following output:

Lamech begat Tubalcain Jabal Jubal.
Methusael begat Lamech.
Seth begat Enos.
Adam begat Seth Cain Abel.
Cain begat Enoch.
Enoch begat Irad.
Irad begat Mahujael.
Mehujael begat Methusael.

I wanted to know if the output is what you are looking for.

---

Clarification of Question by derekwtp-ga on 04 Mar 2003 11:59 PST

I looked up while <> and I found that it is used for filehandleing,
but a) why would it be used in this example and b) how can you
traverse the hash using it?

---

Clarification of Question by derekwtp-ga on 04 Mar 2003 12:01 PST

yeah that is the output I was looking for. What did you modify?

Hi derekwtp, 
I have commented what I changed in the original code:

#!/usr/bin/perl -w 
   
   
  %father = ( 
  Cain  => "Adam", 
  Abel  => "Adam", 
  Seth  => "Adam", 
  Enoch => "Cain", 
  Irad  => "Enoch", 
  Mahujael  => "Irad", 
  Methusael => "Mehujael", 
  Lamech    => "Methusael", 
  Jabal => "Lamech", 
  Jubal => "Lamech", 
  Tubalcain => "Lamech", 
  Enos  => "Seth" ); 
   
   
   while ( ($k,$v) = each %father) { 
  push( @{$children{$v} }, $k ); 

#added -->
push(@justfathers,$k);
#<--
  } 
   
  #$_ = ','; 
  #while (<>) {   

#added -->
foreach(@justfathers) {
#<--

  chomp; 
  if ($children{$_}) { 
  @children=@{$children{$_}}; 
  } else { 
  @children = "nobody"; 
  } 
  print "$_ begat @children.\n"; 
  }

cool that works googexpert. Great response

Hi,

While(<>) syntax means it is expecting input from STDIN. When you run
the script, it stops and waits, you enter something and then it moves
further.
It is like @ARGS. 
This is the perl way of expecting input form STDIN.

yeah, but how to do traverse the hash using it?

hi derekwtp,
I appreciate your rating.
thanks.