Test 2

Question 1

What is a function?

Answer 1

A function is a group of statements that exist within a program for the purpose of performing a specific task.

Question 2

What is meant by the phrase “divide and conquer”?

Answer 2

A large task is divided into several smaller tasks that are easily performed.

Question 3

How do functions help you reuse code in a program?

Answer 3

If a specific operation is performed in several places in a program, a function can be written once to perform that operation, and then be executed any time it is needed.

Question 4

How can functions make the development of multiple programs faster?

Answer 4

Functions can be written for the common tasks that are needed by the different programs. Those functions can then be incorporated into each program that needs them.

Question 5

How can functions make it easier for programs to be developed by teams of programmers?

Answer 5

When a program is developed as a set of functions in which each performs an individual task, then different programmers can be assigned the job of writing different functions.

Question 6

A function definition has what two parts?

Answer 6

A function definition has two parts: a header and a block. The header indicates the starting point of the function, and the block is a list of statements that belong to the function.

Question 7

What does the phrase “calling a function” mean?

Answer 7

To call a function means to execute the function.

Question 8

When a function is executing, what happens when the end of the function’s block is reached?

Answer 8

When the end of the function is reached, the computer returns back to the part of the program that called the function, and the program resumes execution at that point.

Question 9

Why must you indent the statements in a block?

Answer 9

Because the Python interpreter uses the indentation to determine where a block begins and ends

Question 10

What is a local variable? How is access to a local variable restricted?

Answer 10

A local variable is a variable that is declared inside a function.

It belongs to the function in which it is declared, and only statements in the same function can access it.

Question 11

What is a variable’s scope?

Answer 11

The part of a program in which a variable may be accessed

Question 12

Is it permissible for a local variable in one function to have the same name as a local variable in a different function?

Answer 12

Yes

Question 13

What are the pieces of data that are passed into a function called?

Answer 13

Arguments

Question 14

What are the variables that receive pieces of data in a function called?

Answer 14

Parameters

Question 15

What is a parameter variable’s scope?

Answer 15

A parameter variable’s scope is the entire function in which the parameter is declared.

Question 16

When a parameter is changed, does this affect the argument that was passed into the parameter?

Answer 16

No

Question 17

The following statements call a function named show_data.

Which of the statements passes arguments by position, and which passes keyword arguments?

a. show_data(name=’Kathryn’, age=25)

b. show_data(‘Kathryn’, 25)

Answer 17

A. Keyword

B. Passes by Position

Question 18

What is the scope of a global variable?

Answer 18

The entire Program

Question 19

Give one good reason that you should not use global variables in a program.

Answer 19

• They make debugging difficult
• Makes a program hard to understand

Question 20

What is a global constant?

Is it permissible to use global constants in a program?

Answer 20

A global constant is a name that is available to every function in the program.

It is permissible to use global constants. Because their value cannot be changed during the program’s execution, you do not have to worry about its value being altered.

Question 21

How does a value-returning function differ from the void functions?

Answer 21

The difference is that a value returning function returns a value back to the statement that called it. A simple function does not return a value.

Question 22

What is a library function?

Answer 22

A prewritten function that performs some commonly needed task

Question 23

Why are library functions like “black boxes”?

Answer 23

The term “black box” is used to describe any mechanism that accepts input, performs some operation (that cannot be seen) using the input, and produces output.

Question 24

What does the following statement do?

x = random.randint(1, 100)

Answer 24

It assigns a random integer in the range of 1 through 100 to the variable x.

Question 25

What does the following statement do? print(random.randint(1, 20))

Answer 25

It prints a random integer in the range of 1 through 20.

Question 26

What does the following statement do? print(random.randrange(10, 20))

Answer 26

It prints a random integer in the range of 10 through 19.

Question 27

What does the following statement do? print(random.random())

Answer 27

It prints a random floating-point number in the range of 0.0 up to, but not including, 1.0.

Question 28

What does the following statement do? print(random.uniform(0.1, 0.5))

Answer 28

It prints a random floating-point number in the range of 0.1 through 0.5.

Question 29

When the random module is imported, what does it use as a seed value for random number generation?

Answer 29

It uses the system time, retrieved from the computer’s internal clock.

Question 30

What happens if the same seed value is always used for generating random numbers?

Answer 30

If the same seed value were always used, the random number functions would always generate the same series of pseudorandom numbers.

Question 31

What is the purpose of the return statement in a function?

Answer 31

It returns a value back to the part of the program that called it.

Question 32

Look at the following function definition: def do_something(number): return number * 2 a. What is the name of the function? b. What does the function do? c. Given the function definition, what will the following statement display?

Answer 32

a . do_something b. It returns a value that is twice the argument passed to it. c. 20

Question 33

What is a Boolean function?

Answer 33

A function that returns either True or False

Question 34

What import statement do you need to write in a program that uses the math module?

Answer 34

import math

Question 35

Write a statement that uses a math module function to get the square root of 100 and assigns it to a variable.

Answer 35

square_root = math.sqrt(100)

Question 36

Write a statement that uses a math module function to convert 45 degrees to radians and assigns the value to a variable.

Answer 36

angle = math.radians(45)

Question 37

6.1 What is an output file?

Answer 37

A file to which a program writes data. It is called an output file because the program sends output to it.

Question 38

What is an input file?

Answer 38

A file from which a program reads data. It is called an input file because the program receives input from it.

Question 39

What three steps must be taken by a program when it uses a file?

Answer 39

(1) Open the file. (2) Process the file. (3) Close the file.

Question 40

In general, what are the two types of files? What is the difference between these two types of files?

Answer 40

Text and binary. A text file contains data that has been encoded as text using a scheme such as ASCII. Even if the file contains numbers, those numbers are stored in the file as a series of characters. As a result, the file may be opened and viewed in a text editor such as Notepad. A binary file contains data that has not been converted to text. As a consequence, you cannot view the contents of a binary file with a text editor.

Question 41

What are the two types of file access? What is the difference between these two?

Answer 41

Sequential and direct access. When you work with a sequential access file, you access data from the beginning of the file to the end of the file. When you work with a direct access file, you can jump directly to any piece of data in the file without reading the data that comes before it.

Question 42

When writing a program that performs an operation on a file, what two file-associated names do you have to work with in your code?

Answer 42

The file’s name on the disk and the name of a variable that references a file object.

Question 43

If a file already exists, what happens to it if you try to open it as an output file (using the 'w' mode)?

Answer 43

The file’s contents are erased.

Question 44

What is the purpose of opening a file?

Answer 44

Opening a file creates a connection between the file and the program. It also creates an association between the file and a file object.

Question 45

What is the purpose of closing a file?

Answer 45

Closing a file disconnects the program from the file.

Question 46

What is a file’s read position? Initially, where is the read position when an input file is opened?

Answer 46

A file’s read position marks the location of the next item that will be read from the file. When an input file is opened, its read position is initially set to the first item in the file.

Question 47

In what mode do you open a file if you want to write data to it, but you do not want to erase the file’s existing contents? When you write data to such a file, to what part of the file is the data written?

Answer 47

You open the file in append mode. When you write data to a file in append mode, the data is written to the end of the file’s existing contents.

Question 48

Write a short program that uses a for loop to write the numbers 1 through 10 to a file.

Answer 48

outfile = open('numbers.txt', 'w') for num in range(1, 11): outfile.write(str(num) + '\n') outfile.close()

Question 49

What does it mean when the readline method returns an empty string?

Answer 49

The readline method returns an empty string ('') when it has attempted to read beyond the end of a file.

Question 50

Assume the file data.txt exists and contains several lines of text. Write a short program using the while loop that displays each line in the file.

Answer 50

infile = open('data.txt', 'r') line = infile.readline() while line != '': print(line) line = infile.readline() infile.close()

Question 51

Revise the program that you wrote for Checkpoint 6.14 to use the for loop instead of the while loop.

Answer 51

infile = open('data.txt', 'r') for line in infile: print(line) infile.close()

Question 52

What is a record? What is a field?

Answer 52

A record is a complete set of data that describes one item. A field is a single piece of data within a record.

Question 53

Describe the way that you use a temporary file in a program that modifies a record in a sequential access file.

Answer 53

You copy all the original file's records to the temporary file, but when you get to the record that is to be modified, you do not write its old contents to the temporary file. Instead, you write its new, modified values to the temporary file. Then, you finish copying any remaining records from the original file to the temporary file.

Question 54

Describe the way that you use a temporary file in a program that deletes a record from a sequential file.

Answer 54

You copy all the original file’s records to the temporary file, except for the record that is to be deleted. The temporary file then takes the place of the original file. You delete the original file and rename the temporary file, giving it the name that the original file had on the computer’s disk.

Question 55

Briefly describe what an exception is.

Answer 55

An exception is an error that occurs while a program is running. In most cases, an exception causes a program to abruptly halt.

Question 56

If an exception is raised and the program does not handle it with a try/except statement, what happens?

Answer 56

The program halts.

Question 57

What type of exception does a program raise when it tries to open a nonexistent file?

Answer 57

IOError

Question 58

What type of exception does a program raise when it uses the float function to convert a non-numeric string to a number?

Answer 58

ValueError

Question 59

A group of statements that exist within a program for the purpose of performing a specific task is a(n) _________.

Answer 59

function

Question 60

A design technique that helps to reduce the duplication of code within a program and is a benefit of using functions is_____.

Answer 60

divide and conquer

Question 61

The first line of a function definition is known as the _______.

Answer 61

header

Question 62

You ______ a function to execute it.

Answer 62

call

Question 63

A design technique that programmers use to break down an algorithm into functions is known as _____ .

Answer 63

top-down design

Question 64

A ______ is a diagram that gives a visual representation of the relationships between functions in a program.

Answer 64

hierarchy chart

Question 65

The ______ keyword is ignored by the Python interpreter and can be used as a placeholder for code that will be written later.

Answer 65

pass

Question 66

A ______ is a variable that is created inside a function.

Answer 66

local variable

Question 67

A(n) ____ is the part of a program in which a variable may be accessed.

Answer 67

scope

Question 68

A(n) ______ is a piece of data that is sent into a function.

Answer 68

argument

Question 69

A(n) ______ is a special variable that receives a piece of data when a function is called.

Answer 69

parameter

Question 70

A variable that is visible to every function in a program file is a  ______ .

Answer 70

global variable

Question 71

When possible, you should avoid using _____ variables in a program.

Answer 71

global

Question 72

This is a prewritten function that is built into a programming language.

Answer 72

library function

Question 73

This standard library function returns a random integer within a specified range of values.

Answer 73

random.randint

Question 74

This standard library function returns a random floating-point number in the range of 0.0 up to 1.0 (but not including 1.0).

Answer 74

random.random

Question 75

This standard library function returns a random floating-point number within a specified range of values.

Answer 75

random.uniform

Question 76

This statement causes a function to end and sends a value back to the part of the program that called the function.

Answer 76

return

Question 77

This is a design tool that describes the input, processing, and output of a function.

Answer 77

IPO chart

Question 78

This type of function returns either True or False.

Answer 78

Boolean

Question 79

This is a math module function.

Answer 79

sqrt

Question 80

A file that data is written to is known as a(n) ______.

Answer 80

output file

Question 81

A file that data is read from is known as a(n) ______ .

Answer 81

input file

Question 82

Before a file can be used by a program, it must be  ______ .

Answer 82

opened

Question 83

When a program is finished using a file, it should do this.

Answer 83

close the file

Question 84

The contents of this type of file can be viewed in an editor such as Notepad.

Answer 84

text file

Question 85

This type of file contains data that has not been converted to text.

Answer 85

binary file

Question 86

When working with this type of file, you access its data from the beginning of the file to the end of the file.

Answer 86

sequential access

Question 87

When working with this type of file, you can jump directly to any piece of data in the file without reading the data that comes before it.

Answer 87

direct access

Question 88

This is a small “holding section” in memory that many systems write data to before writing the data to a file.

Answer 88

buffer

Question 89

This marks the location of the next item that will be read from a file.

Answer 89

read position

Question 90

When a file is opened in this mode, data will be written at the end of the file’s existing contents.

Answer 90

append mode

Question 91

This is a single piece of data within a record.

Answer 91

field

Question 92

When an exception is generated, it is said to have been ______.

Answer 92

raised

Question 93

This is a section of code that gracefully responds to exceptions.

Answer 93

exception handler

Question 94

You write this statement to respond to exceptions.

Answer 94

try/except