Confused about Functions

Question

So I'm currently doing an assignment for my python coding class and I have to get the area of a cylinder and I'm supposed to be using functions so it looks cleaner, but I'm not so sure how to exactly do my assignment from scratch, I've watched a lot of videos but can't really seem to understand functions, my code looks like this currently, but whenever I run my code I can't get the "def calc():" part to run, could I get some pointers please?

def info():
    r = float(input("What is the radius of the cylinder? "))
    h = float(input("What is the height of the cylinder? "))
    print("The cylinders area is", area)

def calc():
    pi = 22/7
    area = ((2*pi*r) * h) + ((pi*r**2)*2)
    return pi, area

info()

Answer 1

Don't need so many funcatin.

def info():
    r = float(input("What is the radius of the cylinder? "))
    h = float(input("What is the height of the cylinder? "))
    calc(r,h)
    

def calc(r,h):
    pi = 22/7
    area = ((2*pi*r) * h) + ((pi*r**2)*2)
    print("The cylinders area is", area)
    

info()

Answer 2

in this case I put the radius as 3 and height as 6. You need to define you variables. Then it should work. in this case I used numpy to import an exact pi variable.

Answer 3

You have to put the calc() function above the info() function. You have to actually call the calc() function which will return the area of cylinder. I have provided the code below which should solve your problem. Hope you understand the code!

def calc(r, h): # Calculates the area of cylinder
    pi = 22/7
    area = ((2*pi*r) * h) + ((pi*r**2)*2)
    return area

def info(): # Takes the radius and height from user.
       r = float(input("What is the radius of the cylinder? "))
       h = float(input("What is the height of the cylinder? "))
       
       return f"The area is {calc(r, h)}"
 
# r = 5
# h = 10   
print(info())

# using parameters in functions instead of inputs:

def info2(r, h):
    return f"The area is {calc(r, h)}"

r = 5
h = 10 
print(info2(r, h))

# Comparing areas of cylinders

area1 = calc(5, 10)
area2 = calc(10, 15)

if area1>area2: #Area1 is greater than Area2
    print("Area1 is greater than Area2")
elif area2>area1: #Area2 is greater than Area1
    print("Area2 is greater than Area1")
else: #Both are equal
    print("Both are equal")

Answer 4

You mentioned in a comment that you wanted to input multiple cylinders and determine which was the larger one -- I think for that you want to have your function that inputs a cylinder return the cylinder itself so that it can be compared using the volume function.

from dataclasses import dataclass
from math import pi


@dataclass
class Cylinder:
    radius: float
    height: float
    name: str


def volume(c: Cylinder) -> float:
    return (2*pi*c.radius) * c.height + (pi*c.radius**2)*2


def input_cylinder(name: str) -> Cylinder:
    r = float(input(f"What is the radius of the {name} cylinder? "))
    h = float(input(f"What is the height of the {name} cylinder? "))
    return Cylinder(r, h, name)


if __name__ == '__main__':
    cylinders = [input_cylinder(name) for name in ('first', 'second')]
    for c in cylinders:
        print(f"The {c.name} cylinder's volume is {volume(c)}")
    print(f"The bigger cylinder is the {max(cylinders, key=volume).name} one.")