Chapter 4 : Procedures

Question 1

What is a python ‘if’ structure made out of?

Answer 1

• A header
• A body

Question 2

What must a header have?

Answer 2

• The word if
• A logical test
• A colon

Question 3

What is the header?

Answer 3

It controls the loop and sets the exit condition for the loop.

Question 4

What is the body?

Answer 4

It is the commands that belong inside the loop. These commands are indented under the header.

Question 5

What is a nested structure?

Answer 5

When a program structure is inside of another program structure. It is shown by a double indentation.

Question 6

What is a module?

Answer 6

It is a ready-made block of code with a name that you can use in your program.

Question 7

What is a procedure?

Answer 7

A procedure is a type of module that you can make yourself.

Question 8

How can you use procedures?

Answer 8

1. Define the procedure. Give it a name and store commands inside of it.
2. Call the procedure. Put the name of the procedure in your prograam. All stored commands would be carried out.

Question 9

!! What is the structure of a procedure header?

Answer 9

• The word def
• The name of the procedure
• Open and closed brackets
• Colon

Question 10

!! What must you remember when choosing a procedure name?

Answer 10

• It must be a single word
• It can only contain letters, numbers, and the underscore symbol.
• It must begin with a letter.

Question 11

State 4 advantages of using modular coding.

Answer 11

• Storing code is easier and makes your program shorter and easier to read.
• Work can be shared among a team or group.
• Code stored in a procedure can be stored and reused, saving time and effort.

Question 12

Give 2 examples of built-in functions in python.

Answer 12

• int()
• print()

Question 13

What is modular programming?

Answer 13

It is using modules and procedures in your programming.

Question 14

What is a search term?

Answer 14

A search term is the item you are looking for in a list.

Question 15

What are the commands used in a binary search?

Answer 15

• Sort the list
• Find the midpoint of the list
• Split the list in half at the midpoint.

Question 16

What is the code for sorting a list?

Answer 16

listname.sort()

Question 17

What is a ‘slice’?

Answer 17

It is a part of a list. When you split a list in 2 halves, each half is called a slice.

Question 18

What is the code to find the slice from the 1st element to the 3rd element?

Answer 18

print(atoms [0:3])

Question 19

!! Give an example of a procedure.

Answer 19

def welcome()
print ( “Hello, welcome” )
print ( “=” * 20)

Question 20

What does it mean to ‘call the procedure’?

Answer 20

Calling the procedure means you put the name of the procedure into your program.

Question 21

What should the name of a procedure be?

Answer 21

The name should remind you of what the procedure does.

Question 22

How do you call call a procedure?

Answer 22

By adding the name of the procedure followed by an open and closed bracket.

e.g. linsearch()

Question 23

What does the relational operator ‘in’ do?

Answer 23

It compares a single value and a list. If the value is ‘in’ the list, then the test is true. If it is not ‘in’ the list, the test is false.

Question 24

What are 2 methods that cna be used to search a list?

Answer 24

• Binary Search
• Linear search

Question 25

What is the code to find an element in a list using the relational operator 'in'?

Answer 25

topiclist = ["A", "B", "C", "D,"] topic = input ("enter a topic.") if topic in atoms: print (topic, "is in the list")

Question 26

What is the code to find an element in a list using the relational operator 'in' using the if... else... verson.

Answer 26

topiclist = ["A", "B", "C", "D,"] topic = input ("enter a topic.") if topic in atoms: print (topic, "is in the list") else: print (topic, "is not in the list.")

Question 27

What is the code to find an element in a list by using a linear search?

Answer 27

topic = input ("enter a topic") stop = len(topics) for i in range (stop): if atoms[i] == topic: print (topic, "is found in the list")

Question 28

What are the steps in a linear search algorhithm?

Answer 28

1. The for loop to counts through all the items in the list. 2. It compares each value to the search term. 3. If there is an exact match, it displays a message saying the item is found.

Question 29

What are the steps in a binary search algorhithm?

Answer 29

1. Sort the list into order 2. Find the midpoint of the list 3. Compare the search term to the midpoint if it is higher or lower. 4. Split the list in half and keep the higher or lower half. 5. Keep splitting the list in half until it only has 1 item.

Question 30

How does a linear search work? What are the advantages and disadvantages?

Answer 30

How it works : It looks through every item in the list until it finds the search term. Advantage : Can be used when the list is not sorted. Disadvantage : Can be slow if the list has a lot of items.

Question 31

How does a binary search work? What are the advantages and disadvantages?

Answer 31

How it works : Split the list in half over and over again until it only has one item? Advantage : Uses fewer operations and is faster. Disadvantage : Can only be used if the list is sorted.