[Note: parts of this message were removed to make it a legal post.]
On Tue, Mar 9, 2010 at 10:35 PM, Dhananjay Bhavsar <
Hello
the code is like this
hash_fruit = {}
hash_fruit ['mango']='orange'
hash_fruit ['banana']='yellow'
hash_fruit ['grapes']='green'
hash_fruit ['apple'] = 'red'
hash_fruit .each do |key , value |
puts key + ' '+value
end
and the answer is
apple red
banana yellow
mango orange
grapes green
why is it so?
Your question is ambiguous, but I'll assume it is in regards to the
ordering. A hash table is a data structure intended to give you fast (near
constant time) access to your elements. It is based off of key/value pairs.
So you put in a key/value pair, and later, you can get the value out by
submitting the key.
It does this by deriving a number from the object's state, to determine the
(probable) location of the object in an array that it keeps internally, then
looking ot see if it is there.
Because these numbers are not guaranteed to be in the same sequence you
submitted them, the ordering within the array is not guaranteed.
So when you say hash.each, it is more interested in making sure that you see
each of the elements in the hash, than it is in making sure you see them in
the same order you submitted them. In this way, it is more like a set than
an ordered list.
So you should think about the manner in which you are using the objects, and
decide if a hash is really the data structure you are wanting. Based on your
use, an array may better fit your needs.
array_fruit = Array.new
array_fruit << ['mango' ,'orange']
array_fruit << ['banana','yellow']
array_fruit << ['grapes','green' ]
array_fruit << ['apple' ,'red' ]
array_fruit.each do |key,value|
puts "#{key} #{value}"
end
or
array_fruit = [ ['mango','orange'] , ['banana','yellow'] ,
['grapes','green'] , ['apple','red'] ]
array_fruit.each do |key,value|
puts "#{key} #{value}"
end
or
array_fruit = [ %w(mango orange) , %w(banana yellow) , %w(grapes green) ,
%w(apple red) ]
array_fruit.each do |key,value|
puts "#{key} #{value}"
end
Also notice that if you switch to 1.9, then they will be ordered in the
manner in which they were added. Hashes in Ruby 1.9 preserve insertion
order. (
http://img163.imageshack.us/img163/1726/picture1hrm.png