Checking if a variable is not nil and not zero in ruby

I am using the following code to check if a variable is not nil and not zero

if(discount != nil && discount != 0)
...
end

Is there a better way to do this?

You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized. That would remove one check I suppose, I can't think of anything else.

You could do this:

if (!discount.nil? && !discount.zero?)

The order is important here, because if `discount` is `nil`, then it will not have a `zero?` method. Ruby's short-circuit evaluation should prevent it from trying to evaluate `discount.zero?`, however, if `discount` is `nil`.

<pre><code>
unless [nil, 0].include?(discount)
# ...
end
<code></pre>

class Object
def nil_zero?
self.nil? || self == 0
end
end

# which lets you do
nil.nil_zero? # returns true
0.nil_zero? # returns true
1.nil_zero? # returns false
"a".nil_zero? # returns false

unless discount.nil_zero?
# do stuff...
end

Beware of the usual disclaimers... great power/responsibility, monkey patching leading to the dark side etc.

if (discount||0) != 0
#...
end

I believe the following is good enough for ruby code. I don't think I could write a unit test that shows any difference between this and the original.

if discount != 0
end

if discount and discount != 0
..
end

update, it will `false` for `discount = false`

<pre><code>
unless discount.nil? || discount == 0
# ...
end
<code></pre>

You can convert your empty row to integer value and check zero?.

"".to_i.zero? => true
nil.to_i.zero? => true