Normally, as MidLifeXis states, @_ is the argument list for a sub and @ARGV is the argument list for a script, altho' you could, if you were sufficiently perverse, do this (without affecting @ARGV in the calling context)... 
sub foo {
    local @ARGV = @_;
    .
    .
    .
}

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Note, also, that the context of the my $argument_size = scalar(@ARGV); statement is unclear (the closing brace for either sub doesn't appear to be present), but 
sub verify_function_params
{
 
   my $num = $_[0];
   my $function_name = $_[1];
   my $input =  $_[2];
   my $type = $_[3];
 
 
   my $argument_size = scalar(@_);
 
   print "argument_size is $argument_size\n";
   .
   .

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may well produce the results you (seem to have) expected.

Now, understanding the above, you will probably be able to see why... 

sub verify_function_params
{
 
   my $num = $_[0];
   my $function_name = $_[1];
   my $input =  $_[2];
   my $type = $_[3];
   .
   .

[download]
is usually written as... 
sub verify_function_params
{
   my ($num, $function_name, $input, $type) = @_;
   .
   .

[download]

A user level that continues to overstate my experience :-))

In reply to Re: Can @ARGV work within Perl functions or is it just for script input? by Bloodnok
in thread Can @ARGV work within Perl functions or is it just for script input? by Amphiaraus

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