Home » Ruby programming

Hash.key?(obj) Method with Example in Ruby

Ruby Hash.key?(obj) Method: Here, we are going to learn about the Hash.key?(obj) Method with examples in Ruby programming language.
Submitted by Hrithik Chandra Prasad, on March 12, 2020

Hash.key?(obj) Method

In this article, we will study about Hash.key?(obj) Method. The working of the method can't be assumed because of it's quite a different name. Let us read its definition and understand its implementation with the help of syntax and program codes.

Method description:

This method is a Public instance method and belongs to the Hash class which lives inside the library of Ruby language. Hash.key?() method is used to check whether a key(key-value) is a part of the particular Hash instance or not and that Hash instance should be a normal Hash instance. It will search through the whole Hash and gives you the result according to its search. Let us go through the syntax and demonstrating the program codes of this method.

If you are thinking about what it will return then let me tell you, it will return a Boolean value. The returned value will be true if it finds the key inside the Hash and the return value will be false if it does not find the key to be the part of Hash instance.

Syntax:

    Hash_instance.key?(obj)

Argument(s) required:

This method only takes one parameter and that argument is nothing but the key whose presence we want to check.

Example 1:

=begin
  Ruby program to demonstrate Hash.key? method
=end	

hsh = {"colors"  => "red","letters" => "a", "Fruit" => "Grapes"}

puts "Hash.key? implementation:"

puts "Enter the Key you want to search: "
ky = gets.chomp

if (hsh.key?(ky))
	puts "Key found successfully"
else
	puts "Key not found!"
end

Output

Hash.key? implementation:
Enter the Key you want to search: 
 colors
Key found successfully

Explanation:

In the above code, you can observe that we are invoking the Hash.key?() method on the normal Hash instance. It has returned true when it found the presence of key in the Hash object which is entered by the user.

Example 2:

=begin
  Ruby program to demonstrate Hash.key? method
=end	

hsh = {"colors"  => "red","letters" => "a", "Fruit" => "Grapes"}
hsh1 = {"cars"  => "800","bike" => "pulsar", "phone" => "A50"}
hsh2 = {"one"=> hsh, "two" => hsh1}

puts "Hash.key? implementation:"

puts "Enter the Key you want to search: "
ky = gets.chomp

if (hsh2.key?(ky))
	puts "Key found successfully"
else
	puts "Key not found!"
end

Output

Hash.key? implementation:
Enter the Key you want to search: 
 colors
Key not found!

Explanation:

In the above code, you can verify that Hash.key?() method does not work upon Hash instance which is the collection of multiple Hash instances. It will return false even if the object is a part of the Hash instance.