Re: Passing hash into sub routines (should i use reference?)
Michael Alipio wrote:
Hi,
Suppose I have this code:
#/usr/local/bin/perl use warnings; use strict; use subs 'verify';
my %where=( Gary = Dallas, Lucy = Exeter, Ian = Reading,
Samantha = Oregon );
# Then i open a logfile
open FH, '', $logfile or die Can't open $logfile!: $!;
# Now, for every line in the logfile, I will retrive a particular
string, let's say a person's name and verify if it exists in my hash
above:
while (FH){ (my $person) = $_ =~ /person=(\S+)/; my $personstatus =
verify(\%where,$person);
# And do anything if the personstatus is this and that.
# Now, on my sub verify, I would like to know if the person exists
in my hash.
sub verify { my $where = shift @_; my $person = shift @_; my
$personstatus;
if (exists $$where{$person}){
$personstatus =1; }else { $personstatus = 0; }
$personstatus; }
Am I thinking as this is how it should be done when passing hashes to
a subroutine? My program doesn't work and I know it has something to
do with the my $personstatus line as well as if (exists
$$where{$person} line. Can you show me the right way of passing
hashes to subroutines? Thanks.
I also tried declaring %where as 'our' so that I can use if (exists
%where{$person} instead of if(exists $$where{person}) but i still
can't make it work.
Do you know if I am making any sense here?
Thanks
Why pass a reference to the same hash for every line of the FH? You
have declared the %where hash at the top so it's already available to
the sub-routine. Much simpler:
while (FH) {
my ($person) = $_ =~ /person=(\S+)/; # are you sure this works?
my $personstatus = verify($person);
}
sub verify {
local $_ = shift; # $_ contains $person from while loop
return $where{$_} ? 1 : 0;
}
Or even simpler, dispose of verify() and just do:
while (FH){
my ($person) = $_ =~ /person=(\S+)/;
my $personstatus = $where{$person} ? 1 : 0;
}
The correct way to accept a hashref in a sub-routine is:
sub my_subroutine {
my $hashref = shift;
my $something_else = shift;
# OR:
my ($hashref, $something_else) = @_;
}
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Passing hash into sub routines (should i use reference?)
Hi,
Suppose I have this code:
#/usr/local/bin/perl
use warnings;
use strict;
use subs 'verify';
my %where=(
Gary = Dallas,
Lucy = Exeter,
Ian = Reading,
Samantha = Oregon
);
# Then i open a logfile
open FH, '', $logfile or die Can't open $logfile!: $!;
# Now, for every line in the logfile, I will retrive a particular string, let's
say a person's name and verify if it exists in my hash above:
while (FH){
(my $person) = $_ =~ /person=(\S+)/;
my $personstatus = verify(\%where,$person);
# And do anything if the personstatus is this and that.
# Now, on my sub verify, I would like to know if the person exists in my
hash.
sub verify {
my $where = shift @_;
my $person = shift @_;
my $personstatus;
if (exists $$where{$person}){
$personstatus =1;
}else {
$personstatus = 0;
}
$personstatus;
}
Am I thinking as this is how it should be done when passing hashes to a
subroutine? My program doesn't work and I know it has something to do with the
my $personstatus line as well as if (exists $$where{$person} line.
Can you show me the right way of passing hashes to subroutines? Thanks.
I also tried declaring %where as 'our' so that I can use if (exists
%where{$person} instead of if(exists $$where{person}) but i still can't make
it work.
Do you know if I am making any sense here?
Thanks
Don't pick lemons.
See all the new 2007 cars at Yahoo! Autos.
http://autos.yahoo.com/new_cars.html
Re: Passing hash into sub routines (should i use reference?)
Hi,
I've copied your codes and format them on my editor and it seems run well for
me.
use warnings;
use strict;
my %where=(
Gary = Dallas,
Lucy = Exeter,
Ian = Reading,
Samantha = Oregon
);
my $logfile = 'foo.txt';
open FH, '', $logfile or die Can't open $logfile!: $!;
while (FH){
my ($person) = /person=(\S+)/;
my $personstatus = verify(\%where,$person);
if ($personstatus) {
print $person exist\n;
}
}
close FH;
sub verify {
my $where = shift @_;
my $person = shift @_;
my $personstatus;
if (exists $where-{$person}){ # use '-' operator for hash's reference
#if (exists $$where{$person}){ # this line also can work
$personstatus =1;
}else {
$personstatus = 0;
}
$personstatus;
}
Jeff Pang
2007-01-18
发件人： Michael Alipio
发送时间： 2007-01-18 14:26:00
收件人： begginers perl.org
抄送：
主题： Passing hash into sub routines (should i use reference?)
Hi,
Suppose I have this code:
#/usr/local/bin/perl
use warnings;
use strict;
use subs 'verify';
my %where=(
Gary = Dallas,
Lucy = Exeter,
Ian = Reading,
Samantha = Oregon
);
# Then i open a logfile
open FH, ' ', $logfile or die Can't open $logfile!: $!;
# Now, for every line in the logfile, I will retrive a particular string, let's
say a person's name and verify if it exists in my hash above:
while ( FH ){
(my $person) = $_ =~ /person=(\S+)/;
my $personstatus = verify(\%where,$person);
# And do anything if the personstatus is this and that.
# Now, on my sub verify, I would like to know if the person exists in my
hash.
sub verify {
my $where = shift @_;
my $person = shift @_;
my $personstatus;
if (exists $$where{$person}){
$personstatus =1;
}else {
$personstatus = 0;
}
$personstatus;
}
Am I thinking as this is how it should be done when passing hashes to a
subroutine? My program doesn't work and I know it has something to do with the
my $personstatus line as well as if (exists $$where{$person} line.
Can you show me the right way of passing hashes to subroutines? Thanks.
I also tried declaring %where as 'our' so that I can use if (exists
%where{$person} instead of if(exists $$where{person}) but i still can't make
it work.
Do you know if I am making any sense here?
Thanks
Don't pick lemons.
See all the new 2007 cars at Yahoo! Autos.
http://autos.yahoo.com/new_cars.html
Re: Passing hash into sub routines (should i use reference?)
Hi,
Suppose I have this code:
#/usr/local/bin/perl
use warnings;
use strict;
use subs 'verify';
my %where=(
Gary = Dallas,
Lucy = Exeter,
Ian = Reading,
Samantha = Oregon
);
# Then i open a logfile
open FH, '', $logfile or die Can't open $logfile!: $!;
# Now, for every line in the logfile, I will retrive a particular string,
let's say a person's name and verify if it exists in my hash above:
while (FH){
(my $person) = $_ =~ /person=(\S+)/;
my $personstatus = verify(\%where,$person);
# And do anything if the personstatus is this and that.
# Now, on my sub verify, I would like to know if the person exists in my
hash.
sub verify {
my $where = shift @_;
my $person = shift @_;
my $personstatus;
if (exists $$where{$person}){
$personstatus =1;
}else {
$personstatus = 0;
}
$personstatus;
}
Am I thinking as this is how it should be done when passing hashes to a
subroutine? My program doesn't work and I know it has something to do with
the my $personstatus line as well as if (exists $$where{$person} line.
Can you show me the right way of passing hashes to subroutines? Thanks.
I also tried declaring %where as 'our' so that I can use if (exists
%where{$person} instead of if(exists $$where{person}) but i still can't
make it work.
Do you know if I am making any sense here?
Thanks
Try the following code:
while (FH)
{
(my $person) = $_ =~ /person=(\S+)/;
}
# i am passing just the $person
if (($personstatus = verify($person)==1))
{
print Found $person in hash;
}
else
{
printsorry;
}
sub verify
{
(my $per) = @_;
foreach $temp(sort keys %where)
{
if ($temp eq $per)
{
$found =1 ;
goto xxx;
}
}
xxx:
return $found;
}
Don't pick lemons.
See all the new 2007 cars at Yahoo! Autos.
http://autos.yahoo.com/new_cars.html
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