来自所有关联的值的Ruby方法

hash = { name: 'John', age: 25, city: 'New York' }
values = hash.values
puts values
# 输出：['John', 25, 'New York']

hash = { name: 'John', age: 25, city: 'New York' }
values = hash.values_at(:name, :age)
puts values
# 输出：['John', 25]

hash = { name: 'John', age: 25, city: 'New York' }
value = hash.fetch(:name)
puts value
# 输出：'John'

value = hash.fetch(:gender, 'Unknown')
puts value
# 输出：'Unknown'

value = hash.fetch(:gender) { |key| "Unknown key: #{key}" }
puts value
# 输出：'Unknown key: gender'

hash = { name: 'John', age: 25, city: 'New York' }
selected_hash = hash.select { |key, value| value.is_a?(String) }
puts selected_hash
# 输出：{ name: 'John', city: 'New York' }

hash = { name: 'John', age: 25, city: 'New York' }
hash.each { |key, value| puts "#{key}: #{value}" }
# 输出：
# name: John
# age: 25
# city: New York