How to Check if a Key Exists in a Map in Ruby - Step by Step Examples

How to Check if a Key Exists in a Map in Ruby ?

Answer

To check if a key exists in a hash in Ruby, you can use the key? method. This method returns a boolean value indicating whether the hash contains the specified key.

✐ Examples

1 Checking if a Key Exists Using key? Method

We can check if a key exists in a hash in Ruby using the key? method, which returns true if the hash contains the specified key and false otherwise.

For example,

We start by declaring and initializing a hash named my_map with some key-value pairs. In this example, the hash has string keys and integer values.
We use the key? method to check for a specific key in the hash. The key? method returns a boolean value indicating whether the hash contains the specified key.
We print the result to the console using the puts function.

Ruby Program

my_map = {
    'one' => 1,
    'two' => 2,
    'three' => 3
}

# Check if a key exists using key? method
key_exists = my_map.key?('two')

# Print the result
puts "Does key 'two' exist? #{key_exists}"

Output

Does key 'two' exist? true

2 Checking if a Key Does Not Exist Using key? Method

We can check if a key does not exist in a hash in Ruby using the key? method, which returns false if the hash does not contain the specified key.

For example,

We start by declaring and initializing a hash named my_map with some key-value pairs. In this example, the hash has string keys and integer values.
We use the key? method to check for a specific key in the hash. The key? method returns a boolean value indicating whether the hash contains the specified key.
We print the result to the console using the puts function.

Ruby Program

my_map = {
    'one' => 1,
    'two' => 2,
    'three' => 3
}

# Check if a key does not exist using key? method
key_exists = my_map.key?('four')

# Print the result
puts "Does key 'four' exist? #{key_exists}"

Output

Does key 'four' exist? false

3 Checking Multiple Keys Using key? Method

We can check if multiple keys exist in a hash in Ruby using the key? method, which returns true if the hash contains the specified key and false otherwise.

For example,

We start by declaring and initializing a hash named my_map with some key-value pairs. In this example, the hash has string keys and integer values.
We use the key? method to check for multiple keys in the hash. The key? method returns a boolean value indicating whether the hash contains the specified key.
We print the results to the console using the puts function.

Ruby Program

my_map = {
    'one' => 1,
    'two' => 2,
    'three' => 3
}

# Check if multiple keys exist using key? method
key_exists_one = my_map.key?('one')
key_exists_four = my_map.key?('four')

# Print the results
puts "Does key 'one' exist? #{key_exists_one}"
puts "Does key 'four' exist? #{key_exists_four}"

Output

Does key 'one' exist? true
Does key 'four' exist? false

Summary

In this tutorial, we learned How to Check if a Key Exists in a Map in Ruby language with well detailed examples.

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