PCEP - Python Certified Entry Level

Question 1

What is the difference between a compiler and an interpreter ?

Answer 1

An interpreter will execute code whereas a compiler just translates code from one type to another.

Question 2

How do you write a tab escape character?

Answer 2

A tab escape character is written as \t

Question 3

How do you write a new line escape character?

Answer 3

A new line escape character is written as /n

Question 4

What is Floor Division and what is the symbol to use it?

Answer 4

Floor division //, is a mathematical operation that is used to divide two numbers and obtain the quotient, rounding down to the nearest whole number if necessary.

Question 5

What is Remainder or Mod?

Answer 5

Mod or % will give you the remainder, eg 5 % 3 = 2. This can be used to determine even or odd numbers by using Mod 2, eg 12 % 2 = 0 and 13 % 2 = 1

Question 6

How do you calculate the exponent of a number?

Answer 6

Exponents are calculated using the ** notation

Question 7

What happens when you compare two objects with AND?

Answer 7

When you compare two objects with AND it always returns the last TRUE or the first FALSE

Question 8

How do you concatenate two strings together?

Answer 8

You concatenate two strings together using +

Question 9

How do you concatenate a string to an existing string?

Answer 9

You can use the += operator to concatenate a string to an existing string variable

str1 = “Hello”
str1 += “ World”
# str1 will be “Hello World”

Question 10

How do you concatenate a list of strings by specifying a separator?

Answer 10

Use str.join() to concatenate strings using a separator.

words = [“Hello”, “World”]
separators = “ “
result = separator.join(words)
# result will be “Hello World”

Question 11

How can you use print() to concatenate strings?

Answer 11

str1 = “Hello”
str2 = “World”
print(str1, str2)
# Output will be “Hello World”

Question 12

What is string repetition?

Answer 12

String repetition is the concatenate of multiple copies of a string by using the repetition operator *.

str1 = “Hello”
repeated_str = str1 * 3
# repeated_str will be “HelloHelloHello”

Question 13

What is the format of string slicing?

Answer 13

String slicing is in the format of [start, stop, step]

Question 14

How can you use slicing to reverse a string?

Answer 14

You can reverse a string - str_test[::-1]

Question 15

What do you use to add an item to the end of a list?

Answer 15

You can add elements to the end of a list using the append() method. For example:

my_list = [1, 2, 3]
my_list.append(4)
# my_list is now [1, 2, 3, 4]

Question 16

How can you extend one list with the contents of another?

Answer 16

You can extend a list with the elements of another iterable using the extend() method or the += operator. For example:

my_list = [1, 2, 3]
my_list.extend([4, 5])
# my_list is now [1, 2, 3, 4, 5]

Question 17

How can you update a specific element in a list?

Answer 17

You can update the value of an element at a specific index by assigning a new value directly to that index. For example:

my_list = [1, 2, 3]
my_list[1] = 4
# my_list is now [1, 4, 3]

Question 18

How can you insert an element at a specific point in a list?

Answer 18

You can insert an element at a specific index using the insert() method. For example:

my_list = [1, 2, 3]
my_list.insert(1, 4)
# my_list is now [1, 4, 2, 3]

Question 19

What are the ways of removing an element from a list?

Answer 19

To remove an element from a list you can use remove, pop or del

Question 20

How can you use remove() to remove an element in a list?

Answer 20

You give the specific value to remove and the first occurrence of the value will be removed.

my_list = [1, 2, 3, 2]
my_list.remove(2)
# my_list is now [1, 3, 2]

Question 21

How can you use pop() to remove an element in a list?

Answer 21

Pop is used to remove an element at a specific index.

my_list = [1, 2, 3]
popped_element = my_list.pop(1)
# my_list is now [1, 3] and popped_element is 2

Question 22

How can you use del() to remove an element in a list?

Answer 22

Like pop(), del can be used to remove an element by index, or it can clear the entire list

    my_list = [1, 2, 3]
    del my_list[1]
    # my_list is now [1, 3]

    del my_list[:]
    # my_list is now []

Question 23

How can slicing be used to update multiple elements at once?

Answer 23

my_list = [1, 2, 3, 4, 5]
my_list[1:4] = [10, 20, 30]
# my_list is now [1, 10, 20, 30, 5]

Question 24

What are list comprehensions used for?

Answer 24

List comprehensions are a way to create a new list by applying an expression to each item in an existing list.

Question 25

How are list comprehensions written?

Answer 25

List comprehensions are written:

[expression for item in iterable if condition]

my_list = [1, 2, 3]
updated_list = [x * 2 for x in my_list]
# updated_list is [2, 4, 6]

Question 26

What is the difference between a list and a tuple?

Answer 26

Tuples are immutable meaning they cannot be changed as a list can.

Question 27

How is a tuple denoted?

Answer 27

A tuple is written - my_tuple = (1, 2, 3)

Question 28

Can lists or tuples contain multiple data types?

Answer 28

Both lists and tuples can contain multiple data types :

mixed_tuple = (1, “hello”, 3.14, True)
mixed_list = [1, “hello”, 3.14, True]

Question 29

How do you concatenate two tuples?

Answer 29

You concatenate two tuples using the + sign

 tuple1 = (1, 2)
 tuple2 = (3, 4)
 concatenated_tuple = tuple1 + tuple2  # Results in (1, 2, 3, 4)

Question 30

What is tuple repetition?

Answer 30

my_tuple = (1, 2)
repeated_tuple = my_tuple * 3 # Results in (1, 2, 1, 2, 1, 2)

Question 31

What are the two key tuple methods?

Answer 31

The two key tuple methods are count() and index()

 my_tuple = (1, 2, 2, 3, 2)
 count = my_tuple.count(2)  # Returns 3

 my_tuple = (1, 2, 3, 4, 5)
 index = my_tuple.index(3)  # Returns 2

Question 32

What is tuple unpacking?

Answer 32

Tuple unpacking is the assigning of tuple elements to variables in a single line

 my_tuple = (1, 2, 3)
 a, b, c = my_tuple  # a=1, b=2, c=3

Question 33

How can you check if an element exists in a tuple?

Answer 33

You can check if an element exists in a tuple using the in operator.

 my_tuple = (1, 2, 3)
 exists = 2 in my_tuple  # Returns True

Question 34

How can you check the length of a tuple?

Answer 34

You can find the length (number of elements) of a tuple using the len() function.

 my_tuple = (1, 2, 3)
 length = len(my_tuple)  # Returns 3

Question 35

How do you return a list of all the keys/values in a dictionary?

Answer 35

You can use the following:

my_dict = {‘name’: ‘Alice’, ‘age’: 30, ‘city’: ‘New York’}

keys = my_dict.keys()
values = my_dict.values()

Question 36

How do you return both key and values as a list of key-value pairs?

Answer 36

The following will return a tuple of all key/value pairs:

items = my_dict.items()

Question 37

How do you return the value associated with a given key if it exists, otherwise return a default value?

Answer 37

To return a value for a key else if it doesn’t exist return a default you do the following:

my_dict = {‘name’: ‘Alice’, ‘age’: 30, ‘city’: ‘New York’}
age = my_dict.get(‘age’, 0) # Returns 30
salary = my_dict.get(‘salary’, 0) # Returns 0 (default value)

Question 38

What is the .update() method used to do with dictionaries?

Answer 38

The update() method updates the dictionary with the key-value pairs from another dictionary.

my_dict = {‘name’: ‘Alice’, ‘age’: 30, ‘city’: ‘New York’}
other_dict = {‘city’: ‘San Francisco’, ‘gender’: ‘Female’}
my_dict.update(other_dict)

my_dict = {‘name’: ‘Alice’, ‘age’: 30, ‘city’: ‘San Francisco’, ‘gender’: ‘Female’}

Question 38

What does the dictionary pop() method do?

Answer 38

The pop() method removes the key-pair associated with the specified key and returns the value.

Question 39

What does the popitem() method do and what is it used for?

Answer 39

The popitem() method is used to removes and returns an arbitrary key-value pair as a tuple.

Question 40

How do you remove all items in a dictionary?

Answer 40

To remove all items in a dictionary you use:

my_dict.clear()

Question 41

How do you return the number of key-value pairs in a dictionary?

Answer 41

To return the number of key-value pairs in a dictionary you use:

num_items = len(my_dict)

Question 42

How do you find a specific key in a dictionary?

Answer 42

To find a specific key in a dictionary you would use :

if ‘name’ in my_dict:
print(‘Name is in the dictionary.’)

Question 43

What is a shallow copy of a dictionary and how do you create one?

Answer 43

A shallow copy is one who references the original. So any changes to the original or the shallow copy will be reflected in both.

new_dict = my_dict.copy()

Question 44

How do you return a sorted list of keys from your dictionary?

Answer 44

To return a sorted list of keys you use the following:

sorted_keys = sorted(my_dict)

Question 45

How do you concatenate two strings together?

Answer 45

You use the + method to concatenate together two strings

Question 46

How do you get elements from a list and write it to a string?

Answer 46

You use the join() method to write list elements to a string.

words = [‘Hello’, ‘world’, ‘how’, ‘are’, ‘you?’]
sentence = ‘ ‘.join(words)
print(sentence)
Hello world how are you?

Question 47

How do you return the length of a string?

Answer 47

You use the Len() method to return the length of a string.

Question 48

What are the methods available for string case conversion?

Answer 48

The string case conversion methods are:

• str.upper(): Converts the string to uppercase.
• str.lower(): Converts the string to lowercase.
• str.capitalize(): Capitalizes the first character.
• str.title(): Capitalizes the first character of each word.

Question 49

What are the methods available for string trimming and stripping?

Answer 49

The string trimming and stripping methods are:

• str.strip(): Removes leading and trailing whitespace.
• str.lstrip(): Removes leading whitespace.
• str.rstrip(): Removes trailing whitespace.

Question 50

What are the methods available for string searching?

Answer 50

• str.find(substring): Returns the index of the first occurrence of a substring or -1 if not found.
• str.index(substring): Similar to find() but raises an error if not found.
• str.count(substring): Returns the number of non-overlapping occurrences of a substring.

Question 51

What is the method to find the first occurrence of a substring?

Answer 51

str.find(substring)`: Returns the index of the first occurrence of a substring or -1 if not found

Question 52

What is the difference between str.find(substring) and str.index(substring)?

Answer 52

If the substring is not found, str.find returns -1 but str.index raises and error

Question 53

How do you return the number of non-overlapping occurrences of a substring?

Answer 53

To return the number of non-overlapping occurrences of a substring you use:

str.count(substring)

Question 54

How do you replace all occurrences of old with new in the string?

Answer 54

To replace old with new in a string you use:

str.replace(old, new)

Question 55

How do you split a string using a delimiter?

Answer 55

To split a string using a delimiter you use:

str.split(delimiter)

Question 56

How do you split a string at line breaks?

Answer 56

To split a string at line breaks you use:

str.splitlines()

eg
multi_line_string = “Hello\nWorld\nHow\nAre\nYou”

[‘Hello’, ‘World’, ‘How’, ‘Are’, ‘You’]

Question 57

How do you test if all characters in a string are alphabetic?

Answer 57

To test if all characters are alphabetical you use:

str.isaplha()

Question 58

How do you test if all characters are digits?

Answer 58

To test if all characters are digits you use:

str.isdigit()

Question 59

How do you test if all characters are alphanumeric?

Answer 59

To test if all characters are alphanumeric you use:

str.isalnum()

Question 60

How do you test if all characters are whitespace?

Answer 60

To test if all characters are whitespace you use:

str.isspace()

Question 61

How do you get a slice from a string?

Answer 61

To get a slice from a string you use:

[start:end]

Question 62

How do you convert an object to a string?

Answer 62

To convert an object to a string you use:

str[object]

Question 63

What is a For Loop used for?

Answer 63

A For Loop is used for iterating over a sequence (such as a list, tuple, string, or range) or any iterable object.

Question 64

What is a While Loop used for?

Answer 64

A While Loop is used for repeatedly executing a block of code as long as a specified condition is true.

Question 65

How do you exit a loop prematurely when a condition is met?

Answer 65

To exit a loop early when a condition is met you use break()

Question 66

What is continue() used for in the context of loops?

Answer 66

Continue() is used to skip the rest of the current iteration and continue with the next iteration.

Question 67

How do you loop with an index?

Answer 67

You can use the enumerate() function to iterate over elements of an iterable along with their indices.

• Example:for index, item in enumerate(iterable):

This gives access to both the index and the item

Question 68

What is List Comprehension used for?

Answer 68

List comprehension is a concise and efficient way to create lists in Python.

List Comprehension allows you to generate a new list by applying an expression to each item in an existing iterable (such as a list, tuple, or range) and optionally filtering those items based on a condition.

Question 69

What is an example of a List Comprehension?

Answer 69

new_list = [expression for item in iterable if condition]
~~~
squares_of_evens = [x**2 for x in range(10) if x % 2 == 0]

• expression: The expression that is applied to each item in the iterable to generate the new value.
• item: A variable that represents each item in the iterable.
• iterable: The existing iterable you want to iterate over.
• condition (optional): A condition that filters the items from the iterable. The item is included in the new list only if the condition evaluates to True.

Question 70

What is the difference between a Generator and a standard iterable?

Answer 70

Generators in Python are a type of iterable, similar to lists or tuples, but they are not stored in memory all at once. Instead, they produce values on-the-fly as you iterate over them. This makes generators memory-efficient and well-suited for dealing with large datasets or infinite sequences.

Question 71

How are Generators defined?

Answer 71

Generators are defined using functions with the yield keyword. When a function contains a yield statement, it becomes a generator function. When you call this function, it returns a generator object but doesn’t start executing the function immediately. Instead, it begins executing when you iterate over it.