Week 6: Simple Loops

Question 1

How to search through a specific range of index numbers?

Answer 1

for x in range(1,11)
print(x)

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Question 2

How to search for a specific variable in a list?

Answer 2

for num in nums:
if nums == 3:
print(“found 3!”)
break
print(num)

1, 2, found 3!

Question 3

What is a Nested Loop?

Answer 3

When a loop is inside another loop.

Question 4

What type of loop is this and what might the output be:
for num in nums:
for letter in ‘abc’:
print(num, letter)

Answer 4

Nested.
1 a
1 b
1 c
2 a
2 b
2 c

Question 5

How does an infinite loop happen?

Answer 5

When a while condition becomes False, there is no stoppage of a code.

Question 6

What structure are Loops?

Answer 6

Repetition

Question 7

How can you stop loops?

Answer 7

break

Question 8

Define Iteration.

Answer 8

Path through a lap (#)

Question 9

Define Loop.

Answer 9

Blocks of code that repeat. Can be while, for, or until statements.

Question 10

Define Termination Condition.

Answer 10

What condition ends the loop.

Question 11

Define Block.

Answer 11

Code that is the loop. Contains code that repeats and the code that ends the loop.

Question 12

What is the body of the code?

Answer 12

Code that needs to repeat.

Question 13

What are the 2 types of loop codes and how do they differ?

Answer 13

Pre-Test and Post-Test. In Pre, the condition terminating the code is at the beginning and Python only accepts this type.
Post has the condition terminating the loop at the end and always runs at least once.

Question 14

What would an example of each look like?
a. Pre-Test
b. Post-Test

Answer 14

a.
condition code
—-repeating code
—-termination code
b.
—-repeating code
—-termination code
condition code

Question 15

Give an example of a Test condition.

Answer 15

Until answer_by_user == “no”
or
While user_continue != “Q”

Question 16

What is a Counter/Do Loop?

Answer 16

Easiest to write as its not up to the user, rather we configure how many times this code needs to loop (executes a set # of times).

Question 17

In Do Loops, does the counter need to be declared? And if so, how might you do this?

Answer 17

Yes. Will need to be incrememented (Example: counter += counter).
counter = 0

Question 18

What does the syntax of a Do Loop look like?

Answer 18

counter = int
counter = 1
while counter <= 5:
—-print(counter)
—-counter =+ 1
end loop

Question 19

Tips to debug a loop?

Answer 19

1. If it is an infinite, check to what can make it False.
2. Check if loops are missing a line that implements the counter (counter = counter + 1)
3. End prompt (exit strategy) is missing
4. Syntax error / capitalization errors

Question 20

What does “…step 1” tell the computer to do?

Answer 20

To increment the counter by 1 with each pass or iteration through the loop.

Question 21

Which is it–While/Until or For Loop?
a. Runs a predetermined amount of times?
b. Counting variable is automatically declared?
c. Counting variable must be incremented?

Answer 21

a. For Loop
b. For Loop
c. While/Until

Question 22

What is a Nested Loop? Give an example.

Answer 22

Loop within a Loop.
for noun in nouns:
—-for adj in adjs:
——–print(noun, adj)

Question 23

How many times will Hello print and why:
Counter = 0
while Counter < 3:
—-print(“Hello”)
—-counter = counter + 2

Answer 23

Hello
Hello
1st iteration: because 0 < 3 is True. Prints once.
2nd: because now counter = 2 which is still < 3, True. Prints again.
3rd: Counter gets changes from 2 to 4 and is now False, as it is not < 3.

Question 24

How many times will this print and why:
for i in range(0,5,1):
—-print(“Hello”)

Answer 24

Hello
Hello
Hello
Hello
Hello
because of the 2nd/middle #

Question 25

What does the 1st number tell you here: for i in range (0,5,1)

Answer 25

Where to start, so 0 1 2 3 4

Question 26

What does the 3rd number tell you here: for i in range (0,5,2)

Answer 26

What step (step of 2). Like, how many to skip. Example: Hello -skip Hello -skip Hello

Question 27

Show which to skip in: for i in range(0,10,3)

Answer 27

Hello -skip -skip -skip Hello -skip -skip -skip

Question 28

What does "for i in range" mean?

Answer 28

Means the loop will iterate over each # sequence

Question 29

How many times will the following run and why: range(1,10)

Answer 29

9 because it starts at 1 and goes to 9. Not starting at 0.

Question 30

What is the following: end=

Answer 30

The end parameter in Python's print() function specifies what to print at the end of the output. By default, print() ends with a newline character (\n), which means each print() call outputs on a new line. However, you can change this behavior by setting the end parameter to a different string.

Question 31

What will this output: print("Hello", end=" ") print("World")

Answer 31

Hello World

Question 32

If a Nested Loop where the inner loop executes 10 times, and the outer 8, in total the inner loop will execute __ times.

Answer 32

80

Question 33

What will print: for row in range(1, 6): # Outer loop for rows (1 to 5) for column in range(row): # Inner loop for columns (number of times to print the row number) print(row, end="") print("") # Add new line character after each row

Answer 33

1 22 333 4444 55555

Question 34

What is the (loop) syntax to find the exponent of a #? What is another way?

Answer 34

1. exp = 4 base = 2 result = 1 for x in range(exp): ----result = base * result print(result) 2. result = 2 ** 3 print(result)

Question 35

What does `inp = input('> ')` mean?

Answer 35

`input` command will wait for the user to type some information into the terminal and press `return`. `input` takes an string argument which will be displayed for the user. The information entered by the user is stored in the variable `inp`. All information entered for the `input` command will be stored as a string (even if you type a #).

Question 36

What is an accumulator?

Answer 36

Variables that are integers. They get larger depending on the # the user enters.

Question 37

How do you know if you'll need a counter in your loop code?

Answer 37

When you know how many times you need the code to run, or until a certain condition is met, when you need to accumulate a value over the iterations like summing numbers.

Question 38

How to know if a # is positive or negative?

Answer 38

while answer != "q": ----number = int(input("Enter a number:")) ----if number<0: --------sum_neg = sum_neg + number ----else --------sum_pos = sum_pos + number ----answer = input("Enter q to quit") print("Total Neg Numbers:", sum_neg) print("Total Pos Numbers:", sum_pos)

Question 39

Provide an example of a counter loop with a Do...Loop.

Answer 39

use a while loop. Example: counter = 0 max_count = 5 while True: print("Counter:", counter) counter += 1 if counter >= max_count: break

Question 40

What does the random library do?

Answer 40

Generate random numbers and perform random operations.

Question 41

What is the syntax of the radint function?

Answer 41

random.randint(a, b)