On Tue, 15 Feb 2005, John W. Krahn wrote:
> Oliver Fuchs wrote:
> >Hi,
>
> Hello,
>
> >I am a very beginner to perl so may be this question is stupid or too low
> >leveled then please ignore.
> >
> >I tried to wright a little calculator in perl - nothing difficult - very
> >simple:
> >
> >#!/usr/bin/perl -w
> >
> >print "First value: ";
> >chomp ($value1=<STDIN>);
> >print "Second value: ";
> >chomp ($value2=<STDIN>);
> >print "What operator (+ - * /)? ";
> >chomp ($operator=<STDIN>);
> >if ($operator eq "+") {
> > print ($value1 + $value2, "\n");
> > } elsif ($operator eq "-") {
> > print ($value1 - $value2, "\n");
> > } elsif ($operator eq "*") {
> > print ($value1 * $value2, "\n");
> > } elsif ($operator eq "/") {
> > print ($value1 / $value2, "\n");
> > } else {
> > print "Keep it simple \n";
> > }
>
> You could do something like this:
>
>
> #!/usr/bin/perl -w
> use strict;
>
> my %calc = (
> '+' => sub { return $_[0] + $_[1] },
> '-' => sub { return $_[0] - $_[1] },
> '*' => sub { return $_[0] * $_[1] },
> '/' => sub { return $_[0] / $_[1] },
> );
>
> print 'First value: ';
> chomp( my $value1 = <STDIN> );
> print 'Second value: ';
> chomp( my $value2 = <STDIN> );
> print 'What operator (+ - * /)? ';
> chomp( my $operator = <STDIN> );
>
> if ( exists $calc{ $operator } ) {
> print $calc{ $operator }->( $value1, $value2 ), "\n";
> }
> else {
> print "The operator '$operator' does not exist.\n";
> }
>
>
Hi,
thanks for that (looks better than mine).
> >Originell I tried to put the operator from <STDIN> directly to print like
> >this:
> >
> >[...]
> >print "First value: ";
> >chomp ($value1=<STDIN>;
> >print "Second Value: ";
> >chomp ($value2=<STDIN>;
> >print "Operator: ";
> >chomp ($value3=<STDIN>;
> >
> >print ($value1 $value3 $value2, "\n");
> >
> >But that was malfaunctioning. Is there a way to put the STDIN for the
> >operator directly in the print line or do I always have to keep it that
> >long
> >winded?
>
> You could always use the eval() function:
>
> perldoc -f eval
Thanks again. It worked for me with:
#!/usr/bin/perl -w
print "Enter a expression to calculate:\n";
chomp($expression=<STDIN>);
print eval($expression), "\n";
Oliver
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