Module 5 - Functions cont'd

Question 1

How do you activate a function?

Answer 1

function_name()

*MUST include the parentheses!

Question 2

What is scope?

Answer 2

The place within a program where the variable is defined and can be accessed (local vs. global)

Question 3

Where is local variable scope? Global variable scope?

Answer 3

Local = within the function in which they were created 
Global = entire program

Question 4

Can different functions have the local variables with the same name?

Answer 4

Yes, they don’t see each others’ variables

Question 5

What is an argument?

Answer 5

A piece of data that is passed to the function when you call it:
Function_name(argument)

Question 6

What gets assigned to the parameter variable when the function is called?

Answer 6

The argument value is assigned to the parameter variable when a function is called

Question 7

What is the scope of the parameter?

Answer 7

The scope is the function in which the parameter is used

Question 8

How do you create a global variable? Where can you access a global variable?

Answer 8

To create, write an assignment statement outside all the functions
Can be accessed by ANY statement in the program, including INSIDE functions

Question 9

If a function needs to assign a value to the global variable, how do you do that?

Answer 9

The global variable must be REDECLARED within the function; so, within the function, type:
global variable_name

Question 10

What is a global constant?

Answer 10

References a value that cannot be changed (e.g., pi)

To stimulate in python, create a global variable and DO NOT re-declare it within functions

Question 11

Should you use global variables? why or why not?

Answer 11

No! Best practice is to NOT use them unless code won’t work without it

1. Makes debugging difficult
2. Can’t use functions in another program
3. Program is hard to understand

Question 12

Can the called function change a variable within the calling function?

Answer 12

No! You can pass a value or variable to the called function but you cannot change the variable’s value in the calling function because that variable is out of scope in the called function

Question 13

What is a keyword argument and what is the syntax for it?

Answer 13

Argument that specifies which parameter the value should be passed to
function_name(parameter=value)

Question 14

What’s the difference between void and value-returning functions?

Answer 14

Void functions will perform a task; they consist of statements
Value-returning functions will return a value to the part of the program that called it

Question 15

What is the standard library?

Answer 15

Library of pre-written functions that comes with Python

Library functions have tasks that programmers commonly need (print, input, range, etc.)

Question 16

What are modules?

Answer 16

Files that store the standard library’s functions

Question 17

T or F: Modules containing the related built-in functions are loaded into RAM when you start the interpreter.

Answer 17

False, some are loaded, some you must load by using the import statement (e.g., import math)

Question 18

What is the code for generating a random number between 1 and 5?
What is the data type of the return value?

Answer 18

import random
random.randint(1,5)
It returns an integer

Question 19

What does random.random() function do (after you’ve imported random module)?

Answer 19

Returns a random float between 0.0 and 1.0

does not receive arguments

Question 20

What does the range function do?

Answer 20

Generates the integer numbers between the given start integer to the stop integer
i.e., it returns a range object
(typically used in loops)

Question 21

What does the random.randrange function do?

Answer 21

Similar to range function, but returns randomly selected integer from the resulting sequence

Question 22

What does the random.uniform function do?

Answer 22

Returns a random float but allows user to specify

range

Question 23

T or F: Random number created by functions in random module are actually random.

Answer 23

False, they are pseudo-random numbers

Question 24

What initializes the formula that generates the random numbers?

Answer 24

Seed value
The random module uses the seed value as a base to generate a random number.

Question 25

What does the random module use if seed value is not present? How do you specify desired seed value?

Answer 25

It takes system current time

Can use random.seed()function to specify desired seed value

Question 26

What happens if you provide the same seed value before generating random data?

Answer 26

It will produce the same data

Need to use different seeds in order to get different series of random numbers

Question 27

How do you write a value-returning function?

Answer 27

def function_name(): 
\_\_stmt
\_\_return expression 

the value for expression will be returned to the part of the program that called the function

Question 28

What types of things can you return from a function to the part of the program that called it?

Answer 28

Literal, expression (can be complex), result of another value-returning function

Question 29

What is dead code?

Answer 29

Code that will never be executed (for example, after the ‘return’ statement in a function)

Question 30

What is a temporary variable? Why use it?

Answer 30

A variable used to store an intermediate value in a complex calculation.
They make debugging easier

Question 31

Define incremental development.

Answer 31

A program development plan intended to avoid debugging by adding and testing only a small amount of code at a time.

Question 32

What is scaffolding?

Answer 32

Code that is used during program development but is not part of the final version.
For example, print statements to check values

Question 33

Define guardian.

Answer 33

A programming pattern that uses a conditional statement to check for and handle circumstances that might cause an error.

Question 34

T or F: After a return statement runs, the function continues to execute any subsequent statements

Answer 34

False. As soon as a return statement runs, the function terminates without executing any subsequent statements.