Play with this: 
#!/perl/bin/perl -w

use strict;
use Tk;
use Tk::Button;
use Tk::Entry;

my $row = 0;
my $column = 0;
my $calc = "0.00";
my $buffer;
my %button;

my $mw = tkinit(-title, "Calc");
my $display = $mw->Entry(-width, 20, -justify, 'right', 
    -textvariable, \$calc )
->grid(-column, $column++, -row, $row++, 
       -columnspan, 3, -pady, 2);
$column = 0;

#how to Capture Key Strokes
$mw->bind("<KeyRelease>" , sub { &keypress } );

#use qw to arrange your key layout
for my $i (
qw / 
    7 8 9
    6 5 4
    3 2 1
    0 . C / ) 
{
 $button{$i} = $mw->Button(-text    => "$i", 
              -width   => '5', -height  => '1', 
              -command => sub { &numpress($i)} )
  ->grid(-row => $row,
         -column  => $column, -padx, 2, -pady, 2);

    $column++;
if($column > 2){$column = 0; $row++;}
}


MainLoop;

sub numpress{
    my $num = shift;
    if($num ne "C"){
    $buffer .= $num;
    $calc = sprintf "%0.2f", $buffer;
    }

   if($num eq "C"){  $calc = "0.00"; $buffer = 0.00; }
}

sub keypress{

    my $widget = shift;
    my $e = $widget->XEvent;    # get event object
    my $key = $e->K;
       $key=~s/period/\./ig;

    if( $key =~/c/ig ){ $key = uc $key; 
 
        $button{$key}->invoke; }
    
    if( $key =~/(\d)|\./){ &numpress($key); }

}

[download]

In addition to the other suggestions, here are a few other ideas you might play with... this will show you how to capture keystrokes, invoke the buttons from other subs and load your buttons in different method...

JamesNC

In reply to Re: Syntax error using Tk by JamesNC
in thread Syntax error using Tk by eoin

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