Chapter 3 cards

Question 1

What is an algorithm?

Answer 1

A procedure for solving a problem in terms of:
- the actions to execute
- the order in which these actions execute

Question 2

What is program control?

Answer 2

It specifies the order in which statements (actions) execute in a program.
Python does this with Python’s control statements

Question 3

A(n) ______________ is a procedure for solving a problem. It specifies the ________ to execute and the _______ in which they execute

Answer 3

Algorithm, actions, order

Question 4

What is Pseudocode?

Answer 4

An informal language that helps develop algorithms without having to worry about the strict details of Python synthax. Similar to everyday English. Helps you ‘think out’ a program before attempting to write it in a programming language
- Text describes what the program should do
- Convert text to Python with Python equivalent

Question 5

T/F

Pseudocode is a simple programming language

Answer 5

False
Pseudocode is not a programming language. It’s an artificial and informal language that helps you develop algorithms

Question 6

Define

Sequential execution

Answer 6

Where statements in a program execute in the order in which they’re written

Question 7

Define

Transfer of control

Answer 7

A Python statement that enables you to specify that the next statement to execute may be other than the next one in sequence

Question 8

Explain

How is transfer of control achieved?

Answer 8

With Python control statements

Question 9

What are the 3 forms of control that all programs be written with?

Answer 9

• Sequential execution
• Selection statement
• Iteration statement (repetition)

Python statements execute ‘in sequence’ unless directed otherwise

Question 10

Define

Flowchart

Answer 10

A ‘graphical’ representation of an algorithm or a part of one

Question 11

Explain

How to draw a flowchart

Answer 11

Draw flowchart using rectangles, diamonds, rounded rectangles and small circles that you connect by arrows called flowlines

Question 12

Why is a flowchart useful?

Answer 12

Helps develop and represent algorithms. They show how forms of control operate.

Question 13

What do we use to indicate an action in a flowchart?

Answer 13

We use rectangle (or action) symbol

Question 14

What shows the order in which actions are executed in a flowchart?

Answer 14

Flowlines

Question 15

What is seen at the beginning of a complete algorithm?

Answer 15

A rounded rectangle containing the word Begin

Question 16

What is the last symbol you see in a completed algorithm?

Answer 16

A rounded rectangle containing the word End

Question 17

When are rounded rectangles omited in an algorithm?

Answer 17

For a part of the algorithm, instead using small circles called connector symbols

Question 18

What is the most important symbol in an algorithm?

Answer 18

Decision or diamond symbol which indicates that a decision is to be made, such as in an if statement

Question 19

What are the 3 selection statements that execute code based on a condition (an expression that evaluates to either True or False:

Answer 19

1. If performs an action in a condition is True or skips the action if the condition is False
2. If ….. else statement performs an action if a condition is True or performs a different action if the condition is False
3. If … elif….. else statements perform one of many different actions, depending on the truth or falsity of several conditions

Question 20

Why is the If statement called a single-selection statement?

Answer 20

It selects or ignores a single action (or group of actions).

Question 21

Why is the If… else statement called double-selection statement?

Answer 21

It selects between two different actions (or groups of actions).

Question 22

Why is the If… elif… else statement called multiple-selection statement?

Answer 22

It selects one of many different actions (or groups of actions)

Question 23

What are the 2 keywords Python uses for repetition statements (iteration)?

Answer 23

while and for

Question 24

Define the 2 repetition statement types

Answer 24

• while statement repeats an action (or group of actions) as long as a condition remains true
• for statement repeats an action (or a group of actions) for every item in a sequence of items

Question 25

What are the keywords discussed on this chapter that Python reserbes to implement its features, such as control statements?

Answer 25

if
elif
while
for
True
False
None

Note the bold words start with an uppercase letter

Question 26

What is a quick summary of control statements in this chapter?

Answer 26

• You form each Python program by combining as many control statements of each type as you need for the algorithm the program implements
• With single-entry/single-exit (one way in/one way out) control statements, the exit point of one connects to the entry point of the next (similar to the way a child stacks building blocks – hence, the term control-statement stacking
• Control-statement nexting also connexts control statements – next chapter

Question 27

You can write all programs usiing three forms of control –_____, _______ and _________

Answer 27

Sequential execution
Selection statements
Repetition statements

Question 28

A(n) ________ is a graphical representation of an algorithm

Answer 28

Flowchart