How do I pass parameters to a subroutine?

Question

Hello friends,

I have encountered a difficulty in understanding the subroutine syntax.

using the following code:

sub build_dyne_file{
open(DYNAP, "+>$veri_dir/$dyna_para") or die $!;
    for (keys %hash){
     print DYNAP "#define ",$_," ",$hash{$_}->[$i],"\n";
    }
    close(DYNAP);
}

for (my $i = 0 ; $i <$TEST_QUOTA ; $i++){
    build_dyna_file($i);
}

In the 'build dyne file' subroutine, the 'for loop' iterates over the hash keys, while the $i parameter used inside the external 'for loop'.

I hope you understand the problem, If not - I'll try to explain it more properly.

thanks for any answer.

Answer 1

You need to get the $i parameter in your subroutine:

sub build_dyne_file
{
  open(DYNAP, "+>$veri_dir/$dyna_para") or die $!;

  # the crucial omission...
  my $i = shift;

    for (keys %hash){
        print DYNAP "#define ",$_," ",$hash{$_}->[$i],"\n";
    }
    close(DYNAP);
}

Answer 2

You have to receive the parameter.

sub build_dyne_file { 
    my $i = shift; # take it off the parameter queue
    ...

You declared it with a lexical scope in the lower for loop ( using my ), so therefore only that loop can "see" it. When you pass it to build_dyne_file, you need to receive the parameter.

Please see perlsub