Re^3: Using qw to check for balanced parentheses

Yes, that works a lot better. :-)

Of course, the subroutine could be reduced to just:

sub is_balanced { eval "qw($_[0])" }
[download]

And it will also work with qq as well as with qw.

$ perl -le'
sub is_balanced { eval qq($_[0]) }

my $balanced   = "(1 + 2 * (3 + (5/4) + 8) + 6)";
my $unbalanced1 = "(((1 + 2 * (3 + (5/4) + 8) + 6))";
my $unbalanced2 = "(((1 + 2 * (3 + (5/4) + 8) + 6))))";

print "Is $balanced balanced? ", is_balanced( $balanced ) ? "yes" : "n
+o";
print "Is $unbalanced1 balanced? ", is_balanced( $unbalanced1 ) ? "yes
+" : "no";
print "Is $unbalanced2 balanced? ", is_balanced( $unbalanced2 ) ? "yes
+" : "no";
'
Is (1 + 2 * (3 + (5/4) + 8) + 6) balanced? yes
Is (((1 + 2 * (3 + (5/4) + 8) + 6)) balanced? no
Is (((1 + 2 * (3 + (5/4) + 8) + 6)))) balanced? no
[download]

Comment on Re^3: Using qw to check for balanced parentheses Select or Download Code

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Re^4: Using qw to check for balanced parentheses by ikegami (Patriarch) on Feb 02, 2011 at 02:00 UTC
That won't handle `""` hand `"0"`, but that's easy to fix: `sub is_balanced { eval "qw($_[0]); 1" }` [download]	[reply] [d/l] [select]
Re^4: Using qw to check for balanced parentheses by Anonymous Monk on Feb 02, 2011 at 01:13 UTC
`sub is_balanced2 { not $_[0] =~ tr/)(// % 2; }`	[reply] [d/l]
Re^5: Using qw to check for balanced parentheses by Your Mother (Archbishop) on Feb 02, 2011 at 01:29 UTC
Update: nothing but down votes for this...? This is output from using the above snippet, not suggested results. `)( is balanced ))))(()((( is balanced` [download]	[reply] [d/l]
Re^6: Using qw to check for balanced parentheses by Anonymous Monk on Feb 02, 2011 at 01:46 UTC
balance is in the eye of the beholder	[reply]