Unit 7

Question 1

What is a loop?

Answer 1

A loop is a way to perform a repeated action in your program. It allows us to simplify our code.

Question 2

What are the two different types of loops?

Answer 2

For-loops and while loops.

Question 3

print(“I love Python!”)
print(“I love Python!”)
print(“I love Python!”)
What is bad about writing this code?

Answer 3

It is frustrating to have to write the same code three times in order to get the desired result.
It also increases your chance of making an error when you’re writing your program and it makes it more difficult to follow the logic that you’re using when you’re writing your program.

Question 4

for count in range(0,3):

What are the words “for”, “count”, “in range” “(0,3)” for?

Answer 4

for is the command that we’re using.
“count” is the variable we’re using to keep track of how many times the loop will run.
“in range” tells Python that you want to run your loop in between a range of numbers which in this case is between 0 and 3.

The loop adds one to count each time it runs and the 0 to 3 means that count will start at 0. The loop won’t run anymore when count is equal to 3. It stops immediately.

Always remember to include the colon or your loop won’t work.

Question 5

What should you code to get this as the output?
I love Python! 0
I love Python! 1
I love Python! 2

Answer 5

for count in range(0,3):
print(“I love Python!” + str(count))

Question 6

We can use an integer _____ to replace the numbers in the ___ section of the for loop.

Answer 6

We can use an integer variable to replace the numbers in the range section of the for loop.
For example:
name = input(“Name:”)
times = int(input(“Number of Times: “))
for count in range (0, times):
print(name)

Question 7

How do you count by twos or by threes?

Answer 7

The range can take a third parameter called “step”. This is how much to add to the counting variable each time the loop runs.

Question 8

How do you get this as the output using the for loop?
0
2
4
6
8

Answer 8

for count in range(0,12,2):
print(count)

This is how much to add to the counting variable each time the loops runs.
Basically for the second number in the parameter, the programme would not print it out. So it will generate a sequence of numbers starting from 0 up to (but not including) 12.
This means it starts at 0 and adds 2 each time until it reaches or exceeds 10.

Question 9

Is it true that you can loop through words as well as numbers?

Answer 9

yes just that the structure is a little different.

Question 10

What will the output of these lines of code be?
word = input(“Enter a word:”)
for letter in word:
print (letter)

Answer 10

It will print out each character of a string on a separate line.

Let’s analyse these lines of code.
The first line of this code asks the user for a word.
The next part is our for statement that prints each letter separately. It tells us that for each character (which we’re temporarily storing in a variable called letter) in a string (which we stored in the variable word), do something.
In this case, the “do something” is print out the contents of the temporary variable letter.

the output will be
P
y
t
h
o
n

Question 11

Explain what this code does.

word = input(“Enter a word:”)
letter_to_find = input(“Enter a letter to find: “)
for letter in word:
if letter == letter_to_find:
print(“Found it!”)

Answer 11

The first two lines are getting the information from the user: the word to search and what letter to search for.
instead of printing out the letter, we added an if statement to compare the letter to the letter we’re trying to find. If they are the same (if we found the letter), it prints out the statement that “Found it!”

What do you think will happen if the letter we are trying to find appears more than once? It will print out the word Found it for each letter.
For example:
Enter a word: science
Enter a letter to find: c

Output:
Found it!
Found it!

Question 12

What would the output be for this?
for i in range(0,4):
print(i)

Answer 12

0
1
2
3

Question 13

What would the output be for this?
for i in range(1,5):
print(i)

Answer 13

1
2
3
4

Question 14

What would the output be for this?
for i in range(1,5):
print(i+1)

Answer 14

2
3
4
5

Question 15

When can the while loop be used?

Answer 15

It can be used until another piece of code tells it to stop.

Question 16

Typically, you want to use a _____ when there is a given start and a given end to your loop.

Answer 16

For loop

Question 17

_____ are best used when it will run until something happens inside the loop to tell it not to run anymore.
What do we use to help control that? (Tell it to run until something happens inside the loop to tell it not to run anymore)

Answer 17

While loops.

We use a Boolean variable to help control that. Boolean variables can either be “True” or “False”

Question 18

To generate random numbers, we first need to import Python’s random module. What is the code for that?

Then we call _________________ to produce random numbers for our needs

Answer 18

import random

Then we call different functions in that module to produce random numbers for our needs

Question 19

Is this statement true?
We can use while loops with variables that are not Boolean values as well.

Answer 19

Yes. These can make while loops look like for loops and, sometimes, you can use them interchangeably. It takes practice to learn about the best place to use a for loop and the best place to use a while loop. Remember, a for loop steps through a set number of things whereas a while loop runs until something tells it not to do that.

Question 20

When do we use a for loop and when do we use a while loop?

Answer 20

Remember, a for loop steps through a set number of things whereas a while loop runs until something tells it not to do that.

Question 21

What is the output for this?
i=0
while i<4:
print(i)
i = i +1

Answer 21

0
1
2
3

Question 22

What is the output for this?
i = 0
while i<4:
i = i + 1
print(i)

Answer 22

1
2
3
4

Question 23

What is the output for this?
i = 1
while i<5:
i = i + 1
print(i)

Answer 23

2
3
4
5

Question 24

What is the command that stop a program from running?

Answer 24

The break command
One particularly useful programming technique with while loops is the break command.

Question 25

Is it true that: instead of using a variable containing true or False, you can set your while loop up to run indefinitely.

Answer 25

Yes. Furthermore, when you want to stop the while command from running, you can use the “break” command to exit out of it.

Question 26

What would happen if you did not include the “break” statement in a while loop?

Answer 26

The while loop would run forever. This is called an infinite loop and it’s a common programming error.

Question 27

How do you get out of an infinite loop if you find yourself in one?

Answer 27

A quick way to get out of it is to press Ctrl and C together. That will force your python program to end.

Question 28

For this program how do we add the break command here?

password = “giggles”
no_password = True
while (no_password):
guess = input(“Password:”)
if (guess == password):
print(“You got it!”)
no_password = false
else:
print(“Try again!”)

Answer 28

password = “giggles”
while(True):
guess = input(“Password:”)
if (guess == password):
print(“You got it!”)
break
else:
print(“Try again!”)

Question 29

Code a program that does the following:

Prints out the numbers from 1 to 10.
The program pauses mid-way through and asks the user if they want to continue printing.
If the user answers no, the program quits the loop.

Answer 29

Loop to print out numbers
for i in range(0,10):
# Check mid-way through
if i == 5:
response = input(“Do you want to continue?(yes/no) “)
if response == ‘no’:
break
# Print out number
print(i+1)

Question 30

What is the meaning of nesting loops?

Answer 30

This means you can place a loop inside of a loop to give you greater control over your programs.

Question 31

Is it true that you can nest a for loop inside a while loop, a for loop inside a for loop or even a while loop inside a while loop?

Answer 31

Yes. Just like we put an if statement inside (or nested) our while loop in a previous lecture, you can nest a for loop inside a while loop, a for loop inside a for loop or even a while loop inside a while loop.

Question 32

Analyse this code
factor1 = 5
for factor2 in range (1,13):
print(str(factor1) + “ + “ + str(factor2) + “ = “ +
str(factor1 + factor2) + “\t” + str(factor1) + “ x “ +
str(factor2) + “ = “ + str(factor1 * factor2))

Answer 32

The first thing we do is set the first factor to 5, since that’s number we’re doing the addition and multiplication table for. (First line)

Then, we have our for loop that takes turns setting the second factor to the numbers between 1 and 12. (Second line) The range is set from 1 to 13 because remember that it will stop when it hits 13 and not run the loop (but we want it to run the loop for 12).

Then, we have our print statement printing out the addition and multiplication problem.
The “\t” is a tab character. It inserts white space to make our print out look attractive and readable.

Question 33

Unpredictability can be simulated in computer programming using __________. _________ have applications in computer game programming, computer simulations and other areas where producing an unpredictable result is useful.

Answer 33

Unpredictability can be stimulated in computer programming using random numbers.

Random number generators have applications in computer game programming, computer simulations and other areas where producing an unpredictable result is useful.

Question 34

What are the three different functions for Functions for Random Integers?

Answer 34

1st type

random.randint(a,b) - Returns a random integer in the range of number a to number b.

Random integer from 1 to 10
»>random.randint(1,10)
10

2nd type
random.randrange(stop) - Returns a random integer in the range of 0 to the number given.

Random integer from 0 to 9
»>random.randrange(10)
7

Third type
random.randrange(start,stop,[step]) - Returns a random integer between start (including) and stop (excluding) counting by an optional interval [step].

Random even integer from 0 to 8
»>random.randrange(0,10,2)
6

Question 35

What is the function for random sequence?

Answer 35

random.choice(seq) - Returns a random item from a sequential list

> > > random.choice([‘red’,’green’,’yellow’,’pink’])
‘yellow’

Question 36

What are the two different functions for random floats?

Answer 36

1st type
random.random() - Returns the next random floating point number in the range of 0 to less than 1.

> > > random.random()
0.42229449745952374

2nd type
random.uniform(a,b) - Returns a random floating point number in the range of number a to number b.

> > > random.uniform(1,10)
6.090785644490166

Question 37

What will be the output of the following code snippet?

def fun():
    print('Python is fun')
    
def learn():
    print('Learning Python')
        
more = True
i = 1
while(more):
    i = i + 1
    if i == 4:
        fun()
    elif i == 7:
        more = False
    else:
        learn() Question 1Select one:

a.
Learning Python
Python is fun
Learning Python
Learning Python
Learning Python

b.
Learning Python
Learning Python
Python is fun
Learning Python
Learning Python

c.
Learning Python
Learning Python
Learning Python
Python is fun
Learning Python

d.
Learning Python
Learning Python
Learning Python
Learning Python
Python is fun

Answer 37

b

this is because when i is 2 and then 3, Learning python will be printed twice. Then when i ==4, Python is fun will be printed.
When i == 6 and then i ==7, learning python is again printed twice. Finally, the while loop ends when i == 7

Question 38

When we know the number of times we need to run the loop, the preferred choice of loop construct is the for loop.

Question 2Select one:
True
False

Answer 38

True

Question 39

What will be the output after the loops end?

i = 1
j = 1
amount = 0

while i < 4:
    while j < 4:
        amount = amount + 1
        j = j + 1
    i = i + 1

print(amount) Question 3Select one:

a.
This is an infinite loop.

b.
1

c.
3

d.
9

Answer 39

c

First round of while loop: i =1, j =1 , amount = 1, j =2 , i =2

Second round of while loop: i =2, j= 2, amount = 2, j = 3 i = 3

Third round of while loop:
i = 3, j =3, amount = 3, j =4 , i =4

While loop stops as i is not smaller than 4

print(amount) = 3

Question 40

How many times will “I love Python!” be printed in the code below?

for count in range(150, 200):
    print("I love Python!") Question 4Select one:

a.
49 times

b.
50 times

c.
51 times

d.
It displays an error message.

Answer 40

so for count in range, let’s say for count in range (1, 10)
the for loop will print that statement 1,2,3,4,5,6,7,8,9 which is a total of 9 times (excluding the second number in the parameter)

since 10-1 = 9 (is the number of times it is printed,

then 200-150 = 50 (answer)

Question 41

What will be the output of the code snippet?

for count in range(0,2):
for counter in range(1,3):
print(“Nested Loop”)
Question 5Select one:

a.
Nested Loop
Nested Loop

b.
Nested Loop
Nested Loop
Nested Loop

c.
Nested Loop
Nested Loop
Nested Loop
Nested Loop

d.
Nested Loop
Nested Loop
Nested Loop
Nested Loop
Nested Loop

Answer 41

the first for loop shows that it will only loop twice

the second for loop show that it will loop twice.

so for the first time when the for loop runs, it will be loop two times by the second for loop thus nested loop will be printed twice.

Then for the second time the for loop runs, it will again be loop twice by the second for loop and thus nested loop will be printed twice.

So in total nested loop will be printed four times.

Ans: c

Question 42

Fill in the blank to ensure the program ends correctly.

x = 0
while True:
    x = x + 2
    print(x)
    add_more = input("Add more? (Yes or No): ")
    if add_more == "No":
        print("Goodbye!")
        \_\_\_\_\_\_\_\_\_\_ Question 6Select one:

a.
break

b.
stop

c.
continue

d.
exit

Answer 42

a

Question 43

Which of the following is true about for loops?

Question 7Select one:

a.
for loops must always use the range() function.

b.
for loops cannot be nested.

c.
for loops are ideal if you know ahead of time how many times you want to execute your code.

d.
for loops are controlled using a True/False (Boolean) condition.

Answer 43

Answer: c

a is not true because you can ay something like
for letters in flashcard():
print(letters)

Output:
f
l
a
s
h
c
a
r
d

For option c, it is not true that for loops cannot be nested.

For option d, it is incorrect. while loops are controlled using Boolean conditions. for loops, on the other hand, iterate over a sequence or range of values.

Question 44

What is the output of the following code snippet?

for x in range(1, 2):
    for y in range(1, 9):
        if (x * y % 4 == 0):
            print(x * y) Question 8Select one:

a.
2
6
10
14
18

b.
4
8
12
16

c.
2
4
6
8

d.
4
8

Answer 44

The correct answer is:

d. 4 8

Explanation:
Outer Loop:

for x in range(1, 2) means x will only take the value 1 because range(1, 2) generates values starting from 1 up to (but not including) 2.
Inner Loop:

for y in range(1, 9) means y will take values from 1 to 8 (inclusive).
Condition:

The condition if (x * y % 4 == 0) checks if the product of x and y is divisible by 4.
Analysis of Iterations:

For x = 1:
When y = 1, x * y = 1 * 1 = 1, not divisible by 4.
When y = 2, x * y = 1 * 2 = 2, not divisible by 4.
When y = 3, x * y = 1 * 3 = 3, not divisible by 4.
When y = 4, x * y = 1 * 4 = 4, divisible by 4 → Print 4.
When y = 5, x * y = 1 * 5 = 5, not divisible by 4.
When y = 6, x * y = 1 * 6 = 6, not divisible by 4.
When y = 7, x * y = 1 * 7 = 7, not divisible by 4.
When y = 8, x * y = 1 * 8 = 8, divisible by 4 → Print 8.
Output:
The numbers printed are 4 and 8. Hence, the correct answer is:

d.
4
8

Question 45

Which of the following is true about loops?

*Choose all that apply.

Question 9Select one or more:

a.
You can loop through a string like “banana”.

b.
There is only one way to loop in Python.

c.
Loops help us simplify our programs.

d.
Whitespace is not meaningful in loops.

e.
You can program a loop to go on forever.

f.
Loops cannot be nested.

Answer 45

The correct answers are:

a. You can loop through a string like “banana”.

Explanation: Yes, you can loop through a string like “banana” in Python. For example, you can iterate over each character in the string using a for loop.
python
Copy code
for char in “banana”:
print(char)
c. Loops help us simplify our programs.

Explanation: Loops help us simplify our programs by automating repetitive tasks, reducing the amount of code we need to write, and making the code more readable and efficient.
e. You can program a loop to go on forever.

Explanation: Yes, a loop can run indefinitely if the condition in a while loop is always True, or if there is no exit condition in a for loop. This is called an infinite loop.
python
Copy code
while True:
print(“This will run forever”)
Incorrect Answers:

b. There is only one way to loop in Python.

Explanation: This is false. Python supports multiple ways to loop, such as for loops and while loops.
d. Whitespace is not meaningful in loops.

Explanation: This is false. In Python, whitespace (indentation) is very important, as it defines blocks of code. Improper indentation will result in errors.
f. Loops cannot be nested.

Explanation: This is false. In Python, loops can be nested, meaning you can have one loop inside another loop.
So, the correct answers are:

a, c, e.

Question 46

What is the output of this code snippet?

i = 1

while i > 0:
    i = i + 1
    while i == 10:
        i = i - 10

print(i) Question 10Select one:

a.
1

b.
10

c.
0

d.
This is an infinite loop.

Answer 46

Let’s break down the code step by step:

python
Copy code
i = 1

while i > 0: # The condition i > 0 is True, so the loop will run.
i = i + 1 # i will be incremented by 1 in each iteration.
while i == 10: # When i equals 10, this nested loop will run.
i = i - 10 # This will decrease i by 10.

print(i) # After exiting the loops, print the final value of i.
Analysis:
Initial value of i: i = 1
First iteration of the outer while i > 0:
i = i + 1 → i becomes 2.
The condition i == 10 is False, so the inner loop does not run.
Second iteration of the outer while i > 0:
i = i + 1 → i becomes 3.
The condition i == 10 is False, so the inner loop does not run.
This process continues, incrementing i by 1 until i becomes 10.
When i == 10, the inner loop starts to execute:
i = i - 10 → i becomes 0.
Now i = 0, and since the outer loop’s condition is i > 0, the outer loop terminates.
Final value of i: 0
Thus, the correct answer is:

c. 0