如何使用Getopt :: Std设置默认值？

I am trying to collect the values from command line using Getopt::Std in my Perl script.

我试图在我的Perl脚本中使用Getopt :: Std从命令行收集值。

use Getopt::Std;
$Getopt::Std::STANDARD_HELP_VERSION = 1;
getopts('i:o:p:');
my $inputfile = our $opt_i;
my $outputfile = our $opt_o;
my $parameter_value = our $opt_p;

Here the first two variables ($inputfile,$outputfile) are mandatory but the last variable ($parameter_value) is optional and can be ignored.

这里前两个变量（$ inputfile，$ outputfile）是必需的，但最后一个变量（$ parameter_value）是可选的，可以忽略。

I am trying to set some value by default to the last variable ($parameter_value) when the -p flag is ignored at the command line.

我试图在命令行忽略-p标志时默认将一些值设置为最后一个变量（$ parameter_value）。

I tried using this:

我试过用这个：

my $parameter_value = our $opt_p || "20";

Here its passes the correct value when -p flag is ignored at command line. But the problem is when I am providing some value from the command line (for instance -p 58), the same value 20 is passed to the program instead of 58 which I passed from command line.

这里在命令行忽略-p标志时传递正确的值。但问题是当我从命令行提供一些值时（例如-p 58），相同的值20被传递给程序而不是我从命令行传递的58。

Can you please help me out by pointing the mistakes I am making here?

能否指出我在这里犯的错误，请你帮帮我吧？

Thank you.

谢谢。

4 个解决方案

#1

#/usr/bin/perl

use strict;
use warnings;

use Getopt::Std;

getopts('i:o:p:');
our($opt_i, $opt_o, $opt_p);

my $inputfile = $opt_i;
my $outputfile = $opt_o;
my $parameter_value = $opt_p || "20";

print "$_\n" for $inputfile, $outputfile, $parameter_value;

C:\Temp> ks -iinput -ooutput -p55
input
output
55

C:\Temp> ks -iinput -ooutput
input
output
20

#2

The best thing is to use GetOpt::Long and use a hash instead of individual variables. Then you can pass default values by pre-populating the array

最好的方法是使用GetOpt :: Long并使用哈希而不是单个变量。然后，您可以通过预填充数组来传递默认值

    use Getopt::Long;
    my %opts = (parameter => 20);
    GetOptions( \%opts, 
            'p|parameter=i', 
            'o|outputfile=s',
            'i|inputfile=s'
    ) or die "Invalid parameters!";

    # I didn't bother cloning STANDARD_HELP_VERSION = 1;

#3

I suggest setting the opt variables to defaults prior to calling getopts. Additionally, you can then use the $opt_ variables in your usage message to show the default values.

我建议在调用getopts之前将opt变量设置为默认值。此外，您可以在使用消息中使用$ opt_变量来显示默认值。

use Getopt::Std;
$Getopt::Std::STANDARD_HELP_VERSION = 1;
our $opt_p = 20;
sub HELP_MESSAGE { print " -p  parameter value (default $opt_p)\n"; }
getopts('i:o:p:');
my $inputfile = our $opt_i;
my $outputfile = our $opt_o;
my $parameter_value = our $opt_p;

#4

#/usr/bin/perl
use strict;
use warnings;
use Getopt::Std;

$Getopt::Std::STANDARD_HELP_VERSION = 1;

my %opts = ();
getopts('i:o:p:', \%opts);
my $inputfile = $opts{i};
my $outputfile = $opts{o};
my $parameter_value = $opts{p} || "20";
print "$inputfile, $outputfile, $parameter_value\n";