# dictionary

# A dictionalry is used to save unique key-value pairs. It uses curly brackets.

a = {}    # create an empty dictionary named a
b = {"state": "CA", "zip": 94301}    # create a dictionary named b that holds two key-value pairs "state": "CA"  and   "zip": 94301
print a    # prints {}
print b    # prints {"state": "CA", "zip": 94301}



# accessing the value of a key:

print b["state"]     # print out the value of the key "state".  It prints "CA"

# replace the value of a key:

b["state"] = "NY"    # replace the value of the key "state".  The new value should be "NY"
print b["state"]     # # prints out the new value of the key "state".  It prints "NY"



# add a new key-value pair at the beginning of the dictionary:
 
b["newkey"] = "new value"   # add a new key-value pair whereas the key should be named "newkey" and its value "new value"
print b["newkey"]      # It prints "new value"



# delete a key-value pair from a dictionary:

del b["state"] 
print b    # it prints {"newkey":"new value", "zip": 94301}



# looping through all keys and values in the dictionary:

for key, value in b.items(): 
	print "KEY: ", key, "VALUE: ", value      # prints out all keys and their values of the dictionary. # It prints  KEY: newkey VALUE: new value  and in next line  KEY: zip VALUE: 94301