I'm new to coding and I want to understand nested IF statements. I don't know what I'm doing wrong, the # total amount is what I am struggling with since I am not getting an answer from PyCharm. Much appreciated for those who could help me.

# Dogfood bags in 3 pack sizes and their cost
l = 100
m = 70
s = 40

# Basic questions
size = input("Bag size 20kg(L), 15kg(M), 5kg(S): ")
type = input("For adult dog or puppy dog (A/P): ")

if size.lower() in "l":
    q = input("How many bags of Large size bags? ")
elif size.lower() in "m":
    q = input("How many bags of Medium size bags? ")
elif size.lower() in "s":
    q = input("How many bags of Small size bags? ")

print("*************")

# Finalize output
if type.lower() in "a":
    print(f"Food Type: Adult")
elif type.lower() in "p":
    print(f"Food Type: Puppy")

if size.lower() in "l":
    print(f"Bag size: Large")
elif size.lower() in "m":
    print(f"Bag size: Medium")
elif size.lower() in "s":
    print(f"Bag size: Small")

print(f"Number of bags: {q}")
print()

# Total amount cost

if size.lower() == "l":
    if type.lower() == "a":
        print(f"Total amount with delivery ${q * l}")
    elif type.lower() == "p":
        print(f"Total amount with delivery ${int(q * l) - 5}")

elif size.lower() == "m":
    if type.lower() == "a":
        print(f"Total amount with delivery ${q * l}")
    elif type.lower() == "p":
        print(f"Total amount with delivery ${int(q * l) - 5}")

elif size.lower() == "s":
    if type.lower() == "a":
        print(f"Total amount with delivery ${q * l}")
    elif type.lower() == "p":
        print(f"Total amount with delivery ${int(q * l) - 5}")

CodePudding user response：

Hey it might help people answer your question if you could be more specific with the trouble you are running into. I ran your code and figured out pretty quickly what the problem is. Your IF statements all seemed to work as intended, I found that the only thing that seemed to be wrong with the code is that the total amounts would be way off what I would imagine they should be. In python when you multiply a string by an integer Ex:

> value = "1" * 5

The output is the string repeated the integer amount of times, the in the case above value would be equal to "11111". The problem with your program is that the input() function only returns strings, even if all the characters are numbers. In your case, the q variable is a string all the way until the end of the code. A simple fix to this would be using the int() function, casting the variable to be type integer instead of string.

size = "Small"
q = input(f"How many bags of {size} size bags? ")
q = int(q)

Now if you were to do that same thing as done above with the value variable, the output would be:

> size = "Small"
> q = input(f"How many bags of {size} size bags? ")
How many bags of Small size bags? 2
> q = int(q)
> print(q * 5)
10

Also something to keep in mind is that using the variable name type is very bad practice as it is also the name of a function that tells you the data type of a variable.

CodePudding user response：

Instead of solving the bug for you, I'll try and cover a valuable lesson for life.

Instead of doing multiple conditions to change a single word (Large, Medium, Small) in a question, just store the right word once in a variable and reuse it unconditionally. The code will become much much simpler:

sizes = {
  'l': ('Large', 100)
  'm': ('Medium', 70)
  's': ('Small', 40)
}
size = input("Bag size 20kg(L), 15kg(M), 5kg(S): ")
size = size.lower()
if size not in sizes.keys():
  print('Wrong bag size')
  return
size_description, size_price = sizes[size]
print(f"Bag size: {size_description}")

types = {
  'a': 'Adult',
  'p': 'Puppy'
}
type = input("For adult dog or puppy dog (A/P): ")
type = type.lower()
if size not in types.keys():
  print('Wrong type')
  return
type_description = types[size]
print(f"Food type: {type_description}")

quantity = input(f"How many bags of {size_description} size? ")
quantity = int(quantity)
print(f"Number of bags: {quantity}")

total_price = quantity * size_price
if type == 'a':
  total_price -= 5

Now, let's discuss the changes:

• You never check for the same condition twice, which makes the code much much simpler to understand and maintain
• I added some checks, because your code would fail if the users specifies something other than l/m/s or a/p
• Instead of repeating conditions over and over again, we use a dictionary to map user inputs to expected values without using conditions
• Rearranged prints to be next to the value they depend on. That's a styling decision, but I would advise on taking
• As some1and2 correctly pointed out, you have to cast quantity to get it to work correctly

Hope that helps.