Chapter 4 Error Handling

Question 1

How would you write a code that attempts to work, but if it doesn’t it shows an all encompassing exception?

Answer 1

try:
print(str(8 / 0))
except Exception as e:
print(“sorry, an error occured”)

Question 2

Our code is crashing due to the following error:

ZeroDivisionError

How do we keep it from crashing and output a text explaining the error?

THIS WILL ONLY WORK FOR THIS SINGLE ERROR AND CRASH FOR EVERYTHING ELSE!

Answer 2

try:
print(str(8 \0))
except ZeroDivisionError as e:
print(“Error”)

remember that e is the variable here, we can also print that variable out to display what the error is at the bottom like this:
print(“Error Details: “ + str(e))

Question 3

Why must we turn our error variable into a string to print?

str(e)

Answer 3

This is due to it being an EXCEPTION, which is a class.

Question 4

This term follows exception and will print regardless if an exception happens to help clean up the code

Answer 4

try:
print(str(8 \0))
except ZeroDivisionError as e:
print(“Error”)
finally:
(“fixing the error”)

Question 5

Create a function and describe what it is doing

Answer 5

def ask(prompt):
return input(prompt + “ “)
print(ask(“How many dogs are there?”)

ask <- function name
prompt <- argument

Question 6

If we want more than one conditional statement to be needed to pass as true, what should we use?

Answer 6

And

Question 7

If we want at least on of the conditionals to be true in condistional statement, what do we use?

Answer 7

Or

Question 8

What does an f-string do? Create one

Answer 8

Turns everything into a string
Print(f”{num} is this)

Question 9

Create a function that you supplies a variable back to print that takes the input of year and pc/console and the variable tells you that you like pc/console games from that year

Answer 9

def nathan(type, year):
games = “You like “ + type + “ games from “ + year
return games
print(nathan(“pc”, “1990”))

Question 10

Create a default argument for if you don’t provide one for a defined function

Answer 10

def ask(prompt = “Default answer”):
return print(prompt + “ “)
ask()

Question 11

Define a function with a default argument.
Give the default argument a space at the end.
create an if statement that returns your input prompt as is if it contains a space.
create an else statement that gives your prompt a space if it doesn’t have one

Answer 11

def ask(prompt = “Please enter a value: “)
if prompt.endswith(“ “):
return input(prompt)
else
return input(prompt + “ “)

Question 12

Give a defined function that accepts first last and middle names and give them all a default

Answer 12

def ask(first = “first”, middle = “middle”, last = “last”):
name = first + “ “ + middle + “ “ + last
return name
print(ask(“Joshua”, “Nathan”, “Cahoe”))

Question 13

Can you give only partial default argument in a defined function?

Answer 13

Yes, but it has to be in a way that the interpreter can define it.
ex:
first, middle, last = “last”
first = “first”, middle, last = “last”
These would work because the interpreted can figure out where to put in the arguments you provided

Question 14

create a function that accepts your first middle and last name and puts them in that order to print
Use keyword arguments to supply the info in any order you want and it will still display in the correct order as specified in the function

Answer 14

def ask(first, middle, last):
name = first + “ “ + middle + “ “ + last
return name
print(ask(last = “Cahoe”, first = “Joshua”, middle = “Nathan”))

Question 15

print how many values are in a list
this works for strings too

Answer 15

list = [
“jason”,
“derrick”
]
print(len(list))

Question 16

Create an arbitrary argument for a defined function

Answer 16

def num(*add):
sum = 0
for i in add:
sum += i
return sum
print(num(2, 3, 8))

Question 17

Define scope

Answer 17

Place where data structures and functions are located

def ask(prompt)
the temp variable here is scoped for this ask function since it can only be used here

Question 18

yield vs return

Answer 18

return closes your function whenever it is reached whereas yield will remember the last number until it is called again, this happens each time it runs.
This is important because it will save you resources, for example, if you created

Question 19

Create a generator for the 99 bottles song where it will print on it’s own when using a for loop

Answer 19

def song(bottles = 99):
while bottles > 0:
print(str(bottles) + “ bottles of beer on the wall.”)
print(str(bottles) + “ bottles of beer”)
print(“take one down, pass it around”)
bottles -= 1
print(str(bottles) + “ bottles of beer on the wall”)
yield
return True
for i in song(3):
pass

This will print on its own because we have the print function inside. We use pass here to tell python to do nothing and wait for it to do it’s thing
We use return, since that tells our function to stop all together (remember, yield keeps going until it can’t anymore.

Question 20

Create a generator for the 99 bottles song where it stores the song lyrics in a “buffer”

Answer 20

def song(bottles = 99):
while bottles > 0:
verse = str(bottles) + “ bottles of beer on the wall. \n”
verse += str(bottles) + “ bottles of beer \n”
verse += “take one down, pass it around \n”
bottles -= 1
verse += str(bottles) + “ bottles of beer on the wall \n”
yield verse
return True
for i in song(3):
print(i)

Question 21

Strings are immutable in python. When we did the previous iterations, this caused the system to do a lot of work to change it. We can optimize our code by creating the bottle song into a list inside the generator, create that now

Answer 21

def song(bottles = 99):
while bottles > 0:
verse = []
verse.append(str(bottles) + “ bottles of beer on the wall. \n”)
verse.append(str(bottles) + “ bottles of beer \n”)
verse.append(“take one down, pass it around \n”)
bottles -= 1
verse.append(str(bottles) + “ bottles of beer on the wall \n”)
yield ““.join(verse)
return True
for i in song(3):
print(i)

”“.join(verse) combines the lyrics? More on this in chapter 6 I believe

Question 22

What do you call values in a list?

Answer 22

[“elements”, “elements”]

Question 23

how would you change “20” in this list to “17” using an index?
list = [1, 19, 20]

Answer 23

list[2] = 17

Question 24

add 23 to the end of
list = [1, 19, 20]

Answer 24

list.append(23)

Question 25

Add “this” to the beginning of the below list
list =[“donut”, “raisin”]

Answer 25

list.insert(0, “this”)

Question 26

Delete the second entry in the below list and then delete the last entry, but store the last entry in a variable to use later
list = [1, 19, 20]

Answer 26

list.pop(1)
thist = list.pop()