How to Get the Value Associated with a Key in a Map in Ruby

How to Get the Value Associated with a Key in a Map in Ruby ?

Answer

To get the value associated with a key in a hash in Ruby, you can use the square bracket notation or the fetch method. These methods allow you to access the value directly using the key.

✐ Examples

1 Getting the Value Associated with a Key Using Square Bracket Notation

We can get the value associated with a key in a hash in Ruby using the square bracket notation, which returns the value associated with 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 square bracket notation to access the value associated with the key 'two'. The square bracket notation returns the value associated with the specified key.
We store the value in a variable named value.
We print the value to the console using the puts function.

Ruby Program

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

# Get the value associated with a key using square bracket notation
value = my_map['two']

# Print the value
puts "The value associated with key 'two' is: #{value}"

Output

The value associated with key 'two' is: 2

2 Getting the Value Associated with a Key Using fetch Method

We can get the value associated with a key in a hash in Ruby using the fetch method, which returns the value associated with 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 fetch method to access the value associated with the key 'three'. The fetch method returns the value associated with the specified key.
We store the value in a variable named value.
We print the value to the console using the puts function.

Ruby Program

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

# Get the value associated with a key using fetch method
value = my_map.fetch('three')

# Print the value
puts "The value associated with key 'three' is: #{value}"

Output

The value associated with key 'three' is: 3

3 Handling Key Not Found Using fetch Method

We can handle the case where a key is not found in a hash in Ruby using the fetch method, which raises a KeyError if the key is not present.

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 a begin-rescue block to handle the case where the key is not found. Inside the begin block, we use the fetch method to attempt to access the value associated with the key 'four'.
If the key is not found, the fetch method raises a KeyError, which is caught by the rescue block. We print an error message to the console using the puts function.

Ruby Program

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

begin
    # Attempt to get the value associated with a non-existent key using fetch method
    value = my_map.fetch('four')
    puts "The value associated with key 'four' is: #{value}"
rescue KeyError
    # Handle the case where the key is not found
    puts "Key 'four' not found in the hash."
end

Output

Key 'four' not found in the hash.

Summary

In this tutorial, we learned How to Get the Value Associated with a Key in a Map in Ruby language with well detailed examples.

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