Python

Question 1

What is the default return value of a function which doesn’t have an explicit return statement

Answer 1

None

Question 2

What are the “keyword arguments” in functions

Answer 2

Keyword arguments allow to specify the argument names making the code more readable.

Question 3

What does “**kwargs” represent

Answer 3

Dictionary containing the arbitrary number of keyword arguments passed to a function.

Question 4

How can one modify the value of a global variable in a function

Answer 4

By declaring the variable of interest as global at the beginning of the function definition.

Question 5

What is ‘a list’ in Python

Answer 5

Data structure which can hold multiple values called items.

Question 6

There is a numbers list defined as: numbers[1, 5, -10, 500, 766]. What value is returned by following statement: numbers[-2]

Answer 6

500

Question 7

What is a slice

Answer 7

A way to extract a part of a sequence like - sequence[start:stop:step]

Question 8

There is a numbers list defined as: numbers[1, 2, 3, 4, 5]. What is returned by following slice: numbers[:4]

Answer 8

1, 2, 3, 4

Question 9

There is a numbers list defined as: numbers[1, 2, 3, 4, 5]. What is returned by following slice: numbers[2:4]

Answer 9

3, 4

Question 10

There is a numbers list defined as: numbers[1, 2, 3, 4, 5]. What is returned by following slice: numbers[1:]

Answer 10

2, 3, 4, 5

Question 11

There is a numbers list defined as: numbers[1, 2, 3, 4, 5]. What is returned by following slice: numbers[:4:2]

Answer 11

1, 3

Question 12

How to determine the size of a list?

Answer 12

By calling len() function with the list as argument.

Question 13

What does list() function do

Answer 13

It creates a list from an iterable object or either an empty list.

Question 14

What does following list() invokation do:

tuple_data = (1, 2, 3, 4)
newList = list(tuple_data)

Answer 14

It creates a list with same elements as in tuple: [1, 2, 3, 4]

Question 15

What does following list() invokation do:

dict_data = { ‘a’: 1, ‘b’:2, ‘c’:3}
newList = list(dict_data)

Answer 15

It creates a list with ‘key’ from a dictionary:
[‘a’, ‘b’, ‘c’]

Question 16

What does index method do on a list

Answer 16

It returns an index of the first occurrence of the element provided as argument if one is found. Otherwise it throws a “ValueError” exception.

Question 17

What does append method do on a list

Answer 17

It adds an element to end of the list.

Question 18

What does insert method do on a list

Answer 18

It allows insertion of an element anywhere in the list

Question 19

What does remove method do on a list

Answer 19

It removes the first occurrence of given element if such element exists.

Question 20

Are lists mutable or immutable?

Answer 20

Mutable

Question 21

Are strings mutable or immutable

Answer 21

Immutable

Question 22

What is the line continuation character which can be used to stretch the python statement over several lines

Answer 22

\

Question 23

What is a dictionary?

Answer 23

A key-value like data structure.

Question 24

What does dict() function do?

Answer 24

It creates a dictionary.

Question 25

What does following dict function do: dict("color": "green", "name": "annie")

Answer 25

It creates a dictionary with two elements.

Question 26

Is dictionary mutable or immutable data type?

Answer 26

Mutable

Question 27

What does setdefault method do on a dictionary?

Answer 27

It sets the default value for the key if the key is not defined explicitly.

Question 28

What does this statement do: var = {}

Answer 28

It creates an empty dictionary.

Question 29

What does pass keyword do?

Answer 29

Pass keyword is used as a placeholder in places where we might want to add implementation later but not exactly now, like in functions.

Question 30

What does type() function do ?

Answer 30

It tells as the type of the argument that is passed in.

Question 31

What is a "raw" string in Python?

Answer 31

A string prefixed with r which will turn any escape characters into printable ones.

Question 32

What is used for multiline strings?

Answer 32

Multiline strings are enclosed with triple quotes, like """.

Question 33

What does following code do: ‘,'.join([‘cat', ‘dog']) ?

Answer 33

It creates a new string in which all words passed in the iterable object are separated with comma: "cat,dog"

Question 34

What does rjust method do on strings?

Answer 34

It padds the string with spaces (or given characters) to the left so the string is right aligned.

Question 35

What does center method do on strings?

Answer 35

It padds the string with spaces (or given characters) from both sides so the string is in center.

Question 36

What does ljust method do on strings?

Answer 36

It padds the string with spaces (or given characters) to the right so the string is left aligned.

Question 37

What does strip method do on strings?

Answer 37

It removes any whitespace (or given characters) characters from left or the right side of the string.

Question 38

Are tuples mutable or immutable?

Answer 38

Immutable.

Question 39

How do you access cmd arguments from your program?

Answer 39

They are part of sys.argv.

Question 40

What is the module which contains regular expression functions?

Answer 40

re

Question 41

What function can be used to create a regex object?

Answer 41

re.compile()

Question 42

What function can be used to find a first occurrence of the regex pattern?

Answer 42

search()

Question 43

What function can be used to find all occurrences of the regex pattern?

Answer 43

findall()

Question 44

What function can be used to the get grouped regex patterns found in the text?

Answer 44

group()

Question 45

How are groups created in regex patterns?

Answer 45

With parentheses.

Question 46

How to match the literal parentheses within the regex pattern?

Answer 46

By preceding it with '\'.

Question 47

What is the purpose of the pipe '|' in group matching?

Answer 47

It can be used as an or operator to match several different options.

Question 48

What is the meaning of '?' in regex pattern matching?

Answer 48

It states that the pattern matches zero or one time.

Question 49

What is the meaning of '*' in regex pattern matching?

Answer 49

It states that the pattern matches zero or more times.

Question 50

What is the meaning of '+' in regex pattern matching?

Answer 50

It states that the pattern matches one or more times.

Question 51

What is the meaning of curly braces '{}' in regex pattern matching?

Answer 51

They state that the pattern can match specific number of times.

Question 52

What is the meaning of curly braces with two values in regex pattern matching?

Answer 52

They state that the pattern can match minimum and maximum number of times.

Question 53

What does leaving out one of the values from the curly braces mean in regex pattern matching?

Answer 53

It means that there is either no minimum or maximum.

Question 54

What is greedy regex pattern matching?

Answer 54

Greedy matching matches the longest string possible.

Question 55

What is non-greedy regex pattern matching?

Answer 55

Non-greedy matching matches the shortest string possible.

Question 56

What character can be put after curly braces to do a non-greedy regex pattern matching?

Answer 56

Question mark.

Question 57

What does findall() return in regex pattern matching if the pattern contains 0 or 1 group?

Answer 57

A list of strings.

Question 58

What does findall() return in regex pattern matching if the pattern contains 2 or more groups?

Answer 58

A list of tuple of a strings.

Question 59

What is \d in regex pattern matching?

Answer 59

Shorthand for digit characters.

Question 60

What is \w in regex pattern matching?

Answer 60

Shorthand for word characters.

Question 61

What is \s in regex pattern matching?

Answer 61

Shorthand for whitespace characters (space, tab, newline).

Question 62

What is \D in regex pattern matching?

Answer 62

Shorthand for non-digit characters.

Question 63

What is \W in regex pattern matching?

Answer 63

Shorthand for non-word characters.

Question 64

What is \S in regex pattern matching?

Answer 64

Shorthand for non-whitespace characters.

Question 65

How could you make your own characters classes in regex pattern matching?

Answer 65

With square brackets: e.g [aeiou] will match only lowercase vowels.

Question 66

What does caret do in own character classes in regex pattern matching, e.g. [^aeiou]?

Answer 66

It matches all the characters except the ones in the brackets.

Question 67

What does ^ (caret) represent in regex pattern matching (not for own character classes context) ?

Answer 67

It states that a pattern should be at the beginning of the examined string.

Question 68

What does $ represent in regex pattern matching?

Answer 68

It states that a pattern should be at the end of the examined string.

Question 69

What does dot '.' character match in regex pattern?

Answer 69

Any character except newlines.

Question 70

How to make the regex pattern matching case-insenstitive?

Answer 70

By passing re.I to re.compile method.

Question 71

What method can be invoked on regex object to replace matches with some other text?

Answer 71

sub(replacement, originalText)

Question 72

What does re.DOTALL accomplish when working with regexes?

Answer 72

It changes the behavior of the '.' pattern to include newlines when matching text.

Question 73

Which module contains useful folders and files functions?

Answer 73

os module

Question 74

Which module contains useful functions for moving, copying files?

Answer 74

shutil

Question 75

What is provided by shelve module?

Answer 75

Shelve module provides a way to quickly save and restore data from and to python programs by using binary files.

Question 76

What does os.unlink() do ?

Answer 76

It deletes a file.

Question 77

What does os.rmdir() do ?

Answer 77

It removes a directory but only if empty.

Question 78

What does shutil.rmtree() do?

Answer 78

It removes a directory and all its contents.

Question 79

How does one throw/raise an exception?

Answer 79

raise Exception("message")