The not Keyword in Ruby

We will introduce the not keyword in Ruby with examples.

the not Keyword in Ruby

If we want to get an expression and then switch its boolean value, we use the not keyword. If we want to get the expression that is normally returning a true as a result and we want it to return a false, we can use the not keyword before the expression.

The syntax of the not keyword is shown below.

# ruby
a = 5;
if not a < 7
    puts "False"
end

The not keyword works like Ruby’s ! operator. The only difference between them is that the ! operator has the most elevated importance of all operators, and the not operator has the most down.

Now, let’s take different examples and see how to use the not keyword in Ruby. Here is an example.

# Ruby
username = "admin"

if not(username == "Admin" )
puts "Incorrect username!"
else
puts "Welcome, Admin!"
end

Output:

Testing Not Keyword With if-else Statement in Ruby

As we can see from the above example, the above code has returned the incorrect password because it is case-sensitive. Now, let’s take a little more complicated code of the not operator in Ruby.

Consider the code as shown below.

# Ruby
user1 = "admin"
pass = 12345

if not(user1 == "admin" && pass == 12345)
   puts "User and Pass doesn't match!"
else
   puts "Successful Login"
end

On execution, it will produce the following output:

Testing Not Keyword With Complex if-else Statement in Ruby

As we can see from the above example, the statement returned true, and then the not keyword flipped the result. The output was printed from the else statement.

In this way, we can use the not keyword in our code in Ruby for multiple tasks where we want to flip the returned value from true to false or false to true.

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