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Python Python Basics (Retired) Shopping List Shopping List Project

Posted by Jake Nisenboim
Jake Nisenboim
3,374 Points

Understanding Greater than symbol Python "> "

My code is as follows:

shopping_list = list()

print("What should we pick up at the store?")
print("Enter 'DONE' to stop adding items.")

while True:
  new_item = input("> ")

  if new_item == 'DONE':
    break

  shopping_list.append(new_item)
  print("Added! List has {} items.".format(len(shopping_list)))
  continue 

print("Here's your list:")

for item in shopping_list:
  print(item)

I don't understand what the 

while True:
  new_item = input("> ")

means?

while the input of new_item is (What?)

Can someone help me understand what this means ("> ") and why it is being used?

I assume it must mean anything? Because it would be = anything - 'DONE' can be an input for new_item.

Thanks.

1 Answer

Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

Hi Jake

The input method take an argument which is displayed just before the user input. So "> " just resembels a symbol to prompt the user that he need to enter somthing. you then store the user input in a variable called new_item.

 # you could have also written it like so

   new_item = input("Ok so what do you want to pick up ?    " )
Jake Nisenboim
Jake Nisenboim
3,374 Points

Ohh wow makes sense thank you !

Jake Nisenboim
Jake Nisenboim
3,374 Points

One other question -- what does list() represent / mean ?

Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

Hi Jake

a list in python is similar to an array in other languages. you can declare a variable as list like above shopping_list = list() or you could use the shorthand notation of a list which is [], so you could also have declared shopping_list = [] which would be the same thing.

hope that makes sence.

Jake Nisenboim
Jake Nisenboim
3,374 Points

Sorry, I understand what a list is however, not what list() (the open and closing brackets with nothing in it), nor what [] would mean otherwise.

Thanks.

Jake Nisenboim
Jake Nisenboim
3,374 Points

Wait, it just means we are starting an empty list...?

Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

the opening and closing parenthesis means you are creating an object of the built in list class i.e your creating an empty list

so if i have a class called Cat for example and i wanted to create an object of this cat class i would do it like so 

mycat = Cat()

# then if the class Cat has any methods i could access them like so

mycat.weight()