anshulzunke has asked for the wisdom of the Perl Monks concerning the following question:

Hi My program was to ask user a password which should be entered with '*' masking. And after user entered the password, user will be asked to enter another Input, text of which will be visible. For linux its ok. But for windows i am trying to use Windows::Console The code is 


use warnings;
use Win32::Console;

sub readPasswordWindows {
    my $pwdText = shift;
    my $inputValue = "";
    my $StdIn = Win32::Console->new(STD_INPUT_HANDLE);
    my $orig_mode = $StdIn->Mode();
    
       $StdIn->Mode(ENABLE_PROCESSED_INPUT);
       my $Password = promptPassword($StdIn, $pwdText, '*');
    print "\nPassword = $Password\n";
    $StdIn->Mode($orig_mode);
    
    return $Password;
}

sub promptPassword {
    my ($handle, $prompt, $mask) = @_;
    my ($Password);
    local $| = 1;
    print $prompt;
    $handle->Flush;
    while (my $Data = $handle->InputChar(1)) {
        last if "\r" eq $Data;

        if ("\ch" eq $Data ) {
            if ( "" ne chop( $Password )) {
                print "\ch \ch";
            }
            next;
        }
        $Password .= $Data;
        print $mask;
    }
    return $Password;
}

sub readInput(){
    my $ip  ="";
    print " \n Input : ";
    
    $ip = <STDIN>;
    print "\n input was = $ip";
return;
}
my $pw = readPasswordWindows("Enter password: ");
readInput();

[download]

......................................... This program gives me error in taking input and says: use of uninitialized value in print for $ip Now if i modify my program a bit by calling the readInput(); as last statement from function promptPassword() it all works fine. The code for which is 


use warnings;
use Win32::Console;

sub readPasswordWindows {
    my $pwdText = shift;
    my $inputValue = "";
    my $StdIn = Win32::Console->new(STD_INPUT_HANDLE);
        my $orig_mode = $StdIn->Mode();
    
       $StdIn->Mode(ENABLE_PROCESSED_INPUT);
       my $Password = promptPassword($StdIn, $pwdText, '*');
    print "\nPassword = $Password\n";
    $StdIn->Mode($orig_mode);
    readInput();
    return $Password;
}

sub promptPassword {
    my ($handle, $prompt, $mask) = @_;
    my ($Password);
    local $| = 1;
    print $prompt;
    $handle->Flush;
    while (my $Data = $handle->InputChar(1)) {
        last if "\r" eq $Data;

        if ("\ch" eq $Data ) {
            if ( "" ne chop( $Password )) {
                print "\ch \ch";
            }
            next;
        }
        $Password .= $Data;
        print $mask;
    }
    return $Password;
}

sub readInput(){
    my $ip  ="";
    print " \n Input : ";
    
    $ip = <STDIN>;
    print "\n input was = $ip";
return;
}
my $pw = readPasswordWindows("Enter password: ");

[download]

as far as i am concerned both the programs are same. But a tweaking in program gives problem with using stdin

Replies are listed 'Best First'.
Re: Problem with Windows Console input
by Athanasius (Archbishop) on Feb 21, 2014 at 16:58 UTC

    Hello anshulzunke, and welcome to the Monastery!

    It seems that when the Win32::Console object $StdIn is destroyed, it closes the STDIN filehandle. The solution would be to re-open STDIN in some way. Unfortunately, I don’t know how to do this.

    A possible workaround is to keep $StdIn in existence. For example:

    ...
use feature 'state';
...
sub readPasswordWindows {
    ...
    state $StdIn = Win32::Console->new(STD_INPUT_HANDLE);
    ...

    [download]

    This is a kludge, but it does keep STDIN open and so remove the error, allowing the script to run as intended.

    Hope that helps,

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

[reply]
[d/l]
[select]
      Thanks buddy it works. But yes there should be a way to re open the stdin handle.
[reply]
        But yes there should be a way to re open the stdin handle.

        There is: 

        #! perl -slw
use strict;

close STDIN;

readline(STDIN);

open *STDIN, '<', 'CON:' or die $!;

my $x = readline(STDIN);

print "Got: $x from reopened STDIN";

__END__
C:\test>junk84.pl
readline() on closed filehandle STDIN at C:\test\junk84.pl line 6.
fred
Got: fred
 from reopened STDIN

        [download]
        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]

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