Ruby Hash Tutorial

1. Introduction

In Ruby, a Hash is a collection of key-value pairs where each unique key maps to a value. Hashes are similar to dictionaries in other languages and provide an efficient way to store and look up data.

Common Methods:

1. []: Retrieve value by key.

2. []=: Set value by key.

3. keys: Retrieve all keys.

4. values: Retrieve all values.

5. each: Iterates over key-value pairs.

6. delete: Removes a key-value pair by key.

7. has_key?: Check if a key exists.

8. has_value?: Check if a value exists.

9. fetch: Get a value by key, with an optional default.

10. merge: Combines two hashes.

11. length: Returns the number of key-value pairs.

12. clear: Removes all key-value pairs.

2. Program Steps

1. Initialize a sample hash.

2. Apply and demonstrate the common methods on the initialized hash.

3. Code Program

# Initialize a sample hash sample_hash = { "name" => "John", "age" => 30, "city" => "New York" } puts "Original Hash: #{sample_hash}" # 1. Retrieve the value for "name" name = sample_hash["name"] # 2. Set a value for "profession" sample_hash["profession"] = "Engineer" # 3. Get all keys all_keys = sample_hash.keys # 4. Get all values all_values = sample_hash.values # 5. Iterate over key-value pairs sample_hash.each do |key, value| puts "Key: #{key}, Value: #{value}" end # 6. Remove key "city" sample_hash.delete("city") # 7. Check if "age" key exists has_age = sample_hash.has_key?("age") # 8. Check if value "John" exists has_john = sample_hash.has_value?("John") # 9. Fetch value for "country" with a default country = sample_hash.fetch("country", "Unknown") # 10. Merge two hashes additional_info = { "gender" => "Male", "hobbies" => "Reading" } merged_hash = sample_hash.merge(additional_info) # 11. Get number of key-value pairs num_of_pairs = sample_hash.length # 12. Clear the hash sample_hash.clear puts "\nTransformed Hash:" puts "Name Value: #{name}" puts "All Keys: #{all_keys}" puts "All Values: #{all_values}" puts "Has Key 'age': #{has_age}" puts "Has Value 'John': #{has_john}" puts "Country (with default): #{country}" puts "Merged Hash: #{merged_hash}" puts "Number of Key-Value Pairs: #{num_of_pairs}" puts "Cleared Hash: #{sample_hash}"

Output:

Original Hash: {"name"=>"John", "age"=>30, "city"=>"New York"} Key: name, Value: John Key: age, Value: 30 Key: city, Value: New York Transformed Hash: Name Value: John All Keys: ["name", "age", "profession"] All Values: ["John", 30, "Engineer"] Has Key 'age': true Has Value 'John': true Country (with default): Unknown Merged Hash: {"name"=>"John", "age"=>30, "profession"=>"Engineer", "gender"=>"Male", "hobbies"=>"Reading"} Number of Key-Value Pairs: 3 Cleared Hash: {}

Explanation:

1. The [] method retrieves the value associated with a given key.

2. The []= method assigns a value to a specified key.

3. keys returns all the keys in the hash.

4. values returns all the values in the hash.

5. each allows you to iterate through each key-value pair.

6. delete removes the key-value pair for the given key.

7. has_key? checks if a key exists in the hash.

8. has_value? checks if a certain value exists in the hash.

9. fetch retrieves a value for a given key, but allows for a default value if the key isn't found.

10. merge combines two hashes together.

11. length returns the number of key-value pairs.

12. clear removes all key-value pairs from the hash.


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Ruby Tutorials

Ruby Hash Tutorial Ruby String Tutorial Ruby Array Tutorial Ruby - Match a Pattern in a String Ruby - map Function Example Ruby - reduce Function Example Ruby - select Function Example Ruby - Date and Time Example Ruby - Create and Execute a Basic Thread Ruby - Main Thread and Sub-threads Ruby - Pause Execution of Thread Using sleep Ruby - Terminate a Thread Using Thread.kill Ruby - Check Status of a Thread Using alive? Ruby - Thread Priority Example Ruby - Use Thread.pass for Thread Scheduling Ruby - Thread Local Variables Ruby Convert String to Hash Ruby Convert String to JSON Ruby Convert String to Integer Ruby Convert String to Array Ruby Convert String to Date Ruby Convert String to CamelCase Ruby Convert String to Boolean Ruby Convert String to Float Ruby Convert String to DateTime Ruby Convert Number to String Ruby Convert Number to Binary Ruby Convert Number to Boolean Ruby Convert List to Set Ruby Convert List to String Ruby Convert List to Hash Ruby Convert List to Map Ruby Convert Array to List Ruby Convert Array to Hash Ruby Convert Array to Hash With Index as Key Ruby Convert Array to Set Ruby Convert Array to String Comma Separated Ruby Convert Array of Strings to Integers Ruby Convert Array to JSON Ruby Convert Array of Hashes to JSON Ruby Convert Hash to JSON Ruby Convert Hash to String Ruby Convert Hash to Array Convert Hash Keys to Strings Ruby Convert Date to DateTime Ruby Convert Date to Epoch Ruby Convert Date to TimeStamp Ruby Convert Date to Milliseconds

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