Question

1. Create a Python class named Phonebook with a single attribute called entries. Begin by including a constructor that initializes entries to be an empty dictionary.

2. Next add a method called add_entry that takes a string representing a person’s name and an integer representing the person’s phone number and that adds an entry to the Phonebook object’s dictionary in which the key is the name and the value is the number. For example:

   >>> book = Phonebook()
   >>> book.add_entry('Turing', 6173538919)
   

3. Add a method named contains to your Phonebook class. It should take a parameter name and return True if name is present in the phonebook, and False otherwise. For example:

   >>> book = Phonebook()
   >>> book.contains('Turing')
   False
   >>> book.add_entry('Turing', 6173538919)
   >>> book.contains('Turing')
   True
   

4. Write another method for your Phonebook class called number_for that takes a parameter name and returns the phone number for name in the called Phonebook object. It should return -1 if name is not found. Here is an example:

   >>> book = Phonebook()
   >>> book.add_entry('Turing', 6173538919)
   >>> book.add_entry('Hopper', 6174951000)
   >>> book.number_for('Turing')
   6173538919
   >>> book.number_for('Hopper')
   6174951000
   >>> book.number_for('Codd')
   -1
   

Answer 1

Code:

Output:

Raw Code:

class Phonebook:
   def __init__(self): # Constructor
       self.entries = {} # Initializing entries with an empty dictionary
   def add_entry(self,name,number):
       self.entries[name] = number # adding new entry to entries dictionary
   def contains(self,name):
       if name in self.entries: # Checking if the name is in entries dictionary or not
           return True
       else:
           return False
   def number_for(self,name):
       if self.contains(name): # Checking if the name is in entries dictionary or not
           return self.entries[name] # If the given name is in entries dictionary then it return the phone number for that name.
       else:
           return -1
def main():
   book = Phonebook() # Creating the object for Phonebook class
   # Calling methods and printing the return values
   print(book.contains('Turing'))
   book.add_entry('Turing',6173538919) # Adding new entry
   print(book.contains('Turing'))
   book.add_entry('Hopper',6174951000) # Adding new entry
   print("Number for Turing: " + str(book.number_for('Turing')))
   print("Number for Hopper: " + str(book.number_for('Hopper')))
   print("Number for Codd : "+ str(book.number_for('Codd')))

main() # Calling main function.

If you have any doubts feel free to comment.