How to Iterate Over Keys in a Map in Ruby - Step by Step Examples

How to Iterate Over Keys in a Map in Ruby ?

Answer

To iterate over keys in a hash in Ruby, you can use the each_key method or a for loop. This allows you to access each key in the hash.

✐ Examples

1 Iterating Over Keys Using each_key Method

We can iterate over keys in a hash in Ruby using the each_key method, which provides a convenient syntax for iterating over all keys in the hash.

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 each_key method to iterate over the keys in the hash.
In the block passed to each_key, we access each key.
We print each key to the console using the puts function to verify that we are iterating over all keys.

Ruby Program

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

# Iterate over keys using each_key method
my_map.each_key do |key|
  puts key
end

Output

one
two
three

2 Iterating Over Keys Using for Loop

We can iterate over keys in a hash in Ruby using a for loop with the keys method, which provides a flexible way to access each key in the hash.

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 keys method to get an array of the keys in the hash.
We iterate over the keys using a for loop, accessing each key directly from the array.
We print each key to the console using the puts function to verify that we are iterating over all keys.

Ruby Program

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

# Iterate over keys using for loop
for key in my_map.keys do
  puts key
end

Output

one
two
three

3 Storing and Iterating Over Keys Separately

We can store keys in a separate array and then iterate over the array in Ruby, which provides a way to work with keys independently of their values.

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 declare an array named keys to store the keys from the hash.
We use the keys method to get an array of the keys in the hash and store it in the keys array.
We use a for loop to iterate over the keys array and print each key to the console using the puts function to verify that we have stored all keys separately.

Ruby Program

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

# Store keys in a separate array
keys = my_map.keys

# Iterate over the keys array
for key in keys do
  puts key
end

Output

one
two
three

Summary

In this tutorial, we learned How to Iterate Over Keys in a Map in Ruby language with well detailed examples.

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