Module 4 - Functions

Question 1

What is a function?

Answer 1

A group of statements in a program that perform a specific task
A function is a block of code which only runs when it is called. You can pass data, known as parameters, into a function. A function can return data as a result.

Question 2

What is the ‘divide and conquer’ approach?

Answer 2

The problem is divided into smaller sub-problems and then each problem is solved independently

Question 3

What is modularized programming?

Answer 3

Each task within the program is in its own function
(you have a dishwasher, washing machine, robot vacuum - if one breaks, the other machines won’t be disturbed = MODULARIZATION!)

Question 4

What is a void function?

Answer 4

Simply executes the statements it contains then terminates or stops, without returning a value

Question 5

What is a value-returning function?

Answer 5

Executes the statements it contains, and then it returns a value back to the statement that called it

Question 6

What are the rules for naming functions?

Answer 6

• can only contain numbers, letters and underscores
• cannot start with a number
• cannot use keywords
• case sensitive!

Question 7

Define function syntax

Answer 7

def function_name():
____statement1
____statement2

Question 8

What are the different parts of a function?

Answer 8

Header = keyword and function name, followed by paranthesis and a colon
Body (called blocks) = indented statements included in the function

Question 9

What are the three important things to consider when defining a function?

Answer 9

1. Major goal of the function (this will define the statements inside the function)
2. What input data does it need (this will specify the argument list)
3. What value does it need to give back to the caller (this is the return value)

Question 10

Write a function to determine the larger of two numbers and print it. Then call that function with numbers 7 and 3.

Answer 10

def large_num(num1,num2):
\_\_\_if num1>num2:
\_\_\_\_\_\_\_print(num1)
\_\_\_else:
\_\_\_\_\_\_\_print(num2)

large_num(7,3)

Question 11

What is the main function?

Answer 11

A function that activates (calls) other functions when they are needed
Main function is called when the program starts

Question 12

What does a function look like in a flowchart?

Answer 12

Function call shown as rectangle with vertical bars at each side
Function name is written inside the rectangle
End terminal symbol usually reads ‘return’
Typically draw a separate flowchart for each function

Question 13

What is top down design?

Answer 13

A technique for breaking algorithm into functions

Question 14

What does a hierarchy (structure) chart do?

Answer 14

Depicts relationship between functions

Boxes represent functions; lines connecting boxes represent the functions called by each function

Question 15

What is the math module?

Answer 15

Part of standard library that contains functions that are useful for performing mathematical calculations

Question 16

How do you access the math module?

Answer 16

Use import statement “import math”

Question 17

How do you access the math functions?

Answer 17

To access one of the functions, you have to specify the name of the module and the name of the function, separated by a dot (also known as a period). This format is called dot notation:

math. sin(x)
math. pi

Question 18

Does the argument of a function have to be a literal?

Answer 18

No, the argument of a function can be any kind of expression, including arithmetic operators:
x = math.sin(degrees / 360.0 * 2 * math.pi)
And even function calls:
x = math.exp(math.log(x+1))
Almost anywhere you can put a value, you can put an arbitrary expression

Question 19

How do you end a function?

Answer 19

Enter an empty line

Question 20

What do you have to keep in mind with flow of execution and functions?

Answer 20

You must define a function before it is called

Question 21

What are parameters?

Answer 21

Variables that arguments get assigned to
When you define a function, the parameter is what’s in the parentheses

Then, when you call it, you enter in your arguments

Question 22

T/F: when you create a variable inside a function, it is local

Answer 22

True

Question 23

Are parameters local or global variables?

Answer 23

Local

Question 24

Is print_twice a void or value-returning function?

Answer 24

Void because it simply performs the task (print the argument twice) without returning a value

Question 25

How can you tell if a function is void or value-returning?

Answer 25

If you assign the result to a variable, then print(variable) the output will be a value called ‘none’

Question 26

Is the value ‘none’ the same as the string ‘none’?

Answer 26

No, it is a special value with its own type ‘NoneType’

Question 27

Write the code to call a function named send_variable and that expects a single int parameter.
Suppose a variable called x refers to an int. Pass this variable as an argument to send_variable.

Answer 27

send_variable(x)

Question 28

What is the syntax of a statement that calls a function?

Answer 28

function_name()

*MUST INCLUDE parentheses even if no arguments!!!

Question 29

Given that add, a function that expects two int parameters and returns their sum, and given that two variables, euro_sales and asia_sales, have already been defined:
Write a statement that calls add to compute the sum of euro_sales and asia_sales and that associates this value with a variable named eurasia_sales.

Answer 29

eurasia_sales=add(euro_sales,asia_sales)