How to Get the Size (Number of Key-Value Pairs) of a Map in Ruby - Step by Step Examples

How to Get the Size (Number of Key-Value Pairs) of a Map in Ruby ?

Answer

To get the size (number of key-value pairs) of a hash in Ruby, you can use the size method. This method returns the number of elements in the hash.

✐ Examples

1 Getting the Size of a Hash Using size Method

We can get the size of a hash in Ruby using the size method, which provides the number of key-value pairs 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 size method to get the number of key-value pairs in the hash.
We store the size in a variable named map_size.
We print the size to the console using the puts function to verify the number of key-value pairs in the hash.

Ruby Program

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

# Get the size of the hash
map_size = my_map.size

# Print the size
puts "Size of the hash: #{map_size}"

Output

Size of the hash: 3

2 Getting the Size of an Empty Hash

We can also get the size of an empty hash in Ruby using the size method, which returns 0 when the hash is empty.

For example,

We start by declaring an empty hash named empty_map with string keys and integer values.
We use the size method to get the number of key-value pairs in the empty hash.
We store the size in a variable named empty_map_size.
We print the size to the console using the puts function to verify that the hash is empty.

Ruby Program

empty_map = {}

# Get the size of the empty hash
empty_map_size = empty_map.size

# Print the size
puts "Size of the empty hash: #{empty_map_size}"

Output

Size of the empty hash: 0

3 Getting the Size of a Hash After Adding Elements

We can get the size of a hash in Ruby after adding elements using the size method, which provides the updated number of key-value pairs in the hash.

For example,

We start by declaring an empty hash named dynamic_map with string keys and integer values.
We add some key-value pairs to the hash using the hash's index notation.
We use the size method to get the number of key-value pairs in the hash after adding elements.
We store the size in a variable named dynamic_map_size.
We print the size to the console using the puts function to verify the updated number of key-value pairs in the hash.

Ruby Program

dynamic_map = {}

# Add elements to the hash
dynamic_map['one'] = 1
dynamic_map['two'] = 2
dynamic_map['three'] = 3

# Get the size of the hash after adding elements
dynamic_map_size = dynamic_map.size

# Print the size
puts "Size of the hash after adding elements: #{dynamic_map_size}"

Output

Size of the hash after adding elements: 3

Summary

In this tutorial, we learned How to Get the Size (Number of Key-Value Pairs) of a Map in Ruby language with well detailed examples.

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How to Get the Size (Number of Key-Value Pairs) of a Map in Ruby - Step by Step Examples