Methods with parameters and return values (Python)

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which method header correctly takes an amount to deposit?

A def deposit(self, amount):

B def deposit(amount, self):

2. A BankAccount has self.balance = 100. What does account.deposit(50) do if deposit is def deposit(self, amount): self.balance += amount?

A balance becomes 150

B balance stays 100

3. When you call account.deposit(50), how many arguments do you write inside the brackets?

A Two: account and 50

B One: 50 (Python passes self for you)

4. Which method sends a calculated value back to the code that called it?

A def get_double(self): return self.balance * 2

B def get_double(self): print(self.balance * 2)

5. Given def get_total(self): return self.price * self.qty, which line stores the result?

A total = item.get_total

B total = item.get_total()

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1def deposit(self, amount):		AA method that takes an extra parameter, amount, after self so the caller can pass in a value to use
2return self.balance * 0.05		BThe method is missing self as its first parameter, so it cannot access self.balance and the call will fail with a TypeError.
3A method changes an attribute using the value passed in as a parameter		CThe method uses print instead of return, so it only displays the value and the caller gets None back.
4A method checks a value with an if statement before it changes an attribute		Dself.balance += amount
5def deposit(amount): self.balance += amount		Eif amount > 0: self.balance += amount
6def get_interest(self): print(self.balance * 0.05)		FSends a calculated value back to the code that called the method

Definitions

def deposit(self, amount):

Fill in the Blanks

Complete each line of code by filling in the missing parts.

def deposit(self, ______): self.balance += amount

def deposit(self, amount): self.balance __ amount

def area(self): ______ self.width * self.height

def withdraw(self, amount): if amount __ self.balance: self.balance -= amount

acc = Account(100) acc._______(50) print(acc.balance)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A class Account:

B def deposit(self, amount):

C self.balance + amount

D return self.balance

Question 2

A class Account:

B def deposit(amount):

C self.balance += amount

Question 3

A class Wallet:

B def spend(self, amount)

C self.cash -= amount

D return self.cash

Question 4

A class Account:

B def withdraw(self, amount):

C if amount = self.bal:

D self.bal -= amount

Question 5

A class Item:

B def total(self, qty):

C sub = self.price * qty

D print(sub)

Answer Key

Methods with parameters and return values (Python)

Section A: Quick Questions

A — def deposit(self, amount):

A — balance becomes 150

B — One: 50 (Python passes self for you)

A — def get_double(self): return self.balance * 2

B — total = item.get_total()

Section B: Match the Pairs

def deposit(self, amount): → A method that takes an extra parameter, amount, after self so the caller can pass in a value to use

return self.balance * 0.05 → Sends a calculated value back to the code that called the method

A method changes an attribute using the value passed in as a parameter → self.balance += amount

A method checks a value with an if statement before it changes an attribute → if amount > 0: self.balance += amount

def deposit(amount): self.balance += amount → The method is missing self as its first parameter, so it cannot access self.balance and the call will fail with a TypeError.

def get_interest(self): print(self.balance * 0.05) → The method uses print instead of return, so it only displays the value and the caller gets None back.

Section C: Definitions

def deposit(self, amount): — A method can take extra parameters after self, like amount, and use return to send a value back to the code that called it.

Section D: Fill in the Blanks

    def deposit(self, amount):
        self.balance += amount

    def deposit(self, amount):
        self.balance += amount

def area(self):
    return self.width * self.height

    def withdraw(self, amount):
        if amount <= self.balance:
            self.balance -= amount

acc = Account(100)
acc.deposit(50)
print(acc.balance)

Section E: Spot the Error

C — This line only calculates a value and throws it away, so the attribute never changes. Use += (self.balance += amount) to update the balance.

B — Every method must list self as its first parameter before any extra parameters. It should be def deposit(self, amount):

B — A method definition must end with a colon. It should be def spend(self, amount):

C — A single = assigns a value, but a condition needs a comparison. To check the amount is not more than the balance, use if amount <= self.bal:

D — print() only shows the value on screen and the method returns None. To send the value back to the caller, use return sub.