Functions

Question

Hi Guys,

Quick question. what is the difference between a function with and without a parameter? I Made this code here that keeps asking the user to input a city name. when the user inputs an empty string, it returns the cities in a list. But i didnt use a parameter in the function, but it still worked, not so sure why.

def cities():
lst=[]

while True:
city = input(‘Enter city’)
if city == ‘ ‘:
return lst
lst.append(city)
print(cities())

Answer 1

If you define a parameter like

def f(x):
...

you MUST call the function with an argument.

If you define it without, like

def f():
...

you MUST NOT give an argument when you call it.

However, if you give your parameter a default value, like

def f(x=1):
...

Then you CAN give an argument, but don't need to - if you don't, then the argument will be 1.