PCEP Practice Exam 1 — 20 Questions

Question 1

According to PEP 8, which of the following is the recommended way to name a constant representing the maximum number of retries?

Accepted Answer

MAX_RETRIES. PEP 8 (Python Enhancement Proposal 8) recommends that constants be named using uppercase letters with underscores separating words, i.e., `MAX_RETRIES`. This convention distinguishes constants from regular variables, which use lowercase with underscores, and helps improve code readability and maintainability.

Answer

max_retries

Answer

1st_retry_limit

Answer

maxRetries

Question 2

A developer writes a function that takes a tuple as an argument and tries to modify an element inside the tuple. What happens?

Accepted Answer

The code raises a TypeError.. Tuples in Python are immutable, meaning their elements cannot be changed after creation. Attempting to modify an element (e.g., `my_tuple[0] = 5`) raises a `TypeError` because the tuple object does not support item assignment. This is a fundamental property of the tuple data type.

Answer

The tuple is converted to a list automatically.

Answer

The first element is modified successfully.

Answer

The code raises a ValueError.

Question 3

The exhibit shows a JSON configuration. Which Python data structure is best suited to represent this configuration?

Accepted Answer

Dictionary. JSON objects map directly to Python dictionaries. Option B (Tuple) is wrong because tuples are immutable and lack key-value mapping. Option C (String) is wrong because a string would lose all structure, making access by key impossible. Option D (List) is wrong because lists are ordered sequences accessed by index, not by key-value pairs.

Answer

Tuple

Answer

String

Answer

List

Question 4

What is the output of the code in the exhibit?

Accepted Answer

3. The code performs integer division using the // operator, which in Python returns the floor of the division result for positive numbers. Since 10 // 3 equals 3 (the integer part of 10/3), the output is 3. Option A is correct because integer division discards the fractional part.

Answer

4

Answer

3.0

Answer

3.3333333333333335

Question 5

A system administrator is writing a Python script to monitor server uptime. The script reads a log file line by line, parses timestamps, and stores them in a list. It then loops through the list to detect gaps longer than 5 minutes that indicate a crash. However, the script keeps missing crashes. The current loop is a for loop that iterates over the list using indices. The administrator suspects the loop logic. The loop uses 'for i in range(len(timestamps)-1): if timestamps[i+1] - timestamps[i] > 300: print("Crash detected")'. Timestamps are integers representing seconds since epoch. What is the most likely cause of missed crashes and the best fix?

Accepted Answer

The timestamps list may not be sorted. The loop assumes timestamps are in chronological order, but if the list is unsorted, adjacent elements may not represent consecutive events, causing the time difference to be negative or misleading, and thus missing actual gaps. Sorting the list before the loop ensures that timestamps[i+1] - timestamps[i] correctly reflects the time between consecutive log entries.

Answer

The loop should use range(len(timestamps)) instead of -1

Answer

The difference should be computed as timestamps[i] - timestamps[i+1]

Answer

The comparison should be > 300, but use > 300.0

Question 6

What does 'print(2 ** 3)' output?

Accepted Answer

8. The ** operator in Python performs exponentiation, raising the left operand (2) to the power of the right operand (3), which equals 8. The print() function then outputs this integer result to the console.

Answer

9

Answer

23

Answer

6

Question 7

Given the code: x = 10; y = 3.0; z = x / y; print(type(z)). What is the output?

Accepted Answer

. In Python, when you divide an integer by a float using the / operator, the result is always a float. Here, x is an integer (10) and y is a float (3.0), so z = 10 / 3.0 evaluates to 3.3333333333333335, which is of type float. The print(type(z)) outputs , making option B correct.

Answer

Answer

Answer

Question 8

Given the code: my_list = [1, 2, 3, 4, 5]. What is the output of print(my_list[-3:-1])?

Accepted Answer

[3, 4]. Python list slicing with negative indices counts from the end of the list. my_list[-3:-1] starts at index -3 (value 3) and goes up to but does not include index -1 (value 5), so it returns [3, 4].

Answer

[4, 5]

Answer

[2, 3]

Answer

[3, 4, 5]

Question 9

A Python script calculates the area of a circle: radius = 5; area = 3.14 * radius ** 2; print(area). What is printed?

Accepted Answer

78.5. 78.5 because the expression `3.14 * radius ** 2` is evaluated according to Python's operator precedence: exponentiation (`**`) has higher precedence than multiplication (`*`), so `radius ** 2` computes 5 squared (25), then multiplied by 3.14 gives 78.5. The `print(area)` function outputs this value.

Answer

157.0

Answer

25.0

Answer

31.4

Question 10

Which loop is more efficient for iterating over a large list when you only need the values, not indices?

Accepted Answer

for value in mylist:. Iterating directly over the list with `for value in mylist:` avoids the overhead of indexing or enumeration. This is the most efficient approach in Python for accessing only the values, as it uses the list's internal iterator, which is implemented in C and involves no function calls or index lookups per iteration.

Answer

for i in range(len(mylist)): value = mylist[i]

Answer

for i, value in enumerate(mylist):

Answer

for value in mylist[::-1]:

Question 11

Which TWO of the following exceptions are built-in Python exceptions? (Select exactly 2)

Accepted Answer

ZeroDivisionError. ZeroDivisionError is a built-in Python exception that is raised when the second operand of a division or modulo operation is zero. It is part of Python's standard exception hierarchy and is commonly encountered in arithmetic operations.

Answer

StringError

Answer

NumberError

Answer

ListError

Question 12

A developer runs the command and sees the output. Which statement about the data type is correct?

Accepted Answer

3.14 is a float in Python.. In Python, numeric literals with a decimal point, such as 3.14, are always interpreted as the built-in float type. Python does not have a separate 'double' type; its float is implemented as a C double (64-bit IEEE 754), but the language itself refers to it as float. This is a fundamental rule of Python's data type system.

Answer

3.14 is a decimal.Decimal type.

Answer

3.14 is a float, but Python also treats it as a double.

Answer

3.14 is a string.

Question 13

You are working on a network automation script that reads a configuration file containing firewall rules. Each rule is a dictionary with keys 'source_ip', 'dest_ip', 'action'. The script must iterate over the rules and print all rules where action is 'allow'. However, the script is not printing any output even though there are allow rules in the file. The code snippet is:

rules = [{'source_ip':'10.0.0.1','dest_ip':'10.0.0.2','action':'allow'},
         {'source_ip':'10.0.0.2','dest_ip':'10.0.0.3','action':'deny'}]
for rule in rules:
    if rule('action') == 'allow':
        print(rule)

What is the most likely cause of the problem?

Accepted Answer

The developer used rule('action') instead of rule['action']. In Python, dictionary values are accessed using square brackets (e.g., rule['action']) or the .get() method, not parentheses. Using parentheses like rule('action') attempts to call the dictionary as a function, which raises a TypeError and prevents the script from executing, so no output is printed even though allow rules exist.

Answer

The dictionary does not have an 'action' key

Answer

The developer used rule['action'] instead of rule.get('action')

Answer

The for loop syntax is incorrect; it should be for rule in rules:

Question 14

What will be printed?

```python
my_list = []
my_list.append('192.168.1.10')
my_list.append('255.255.255.0')
my_list.append('192.168.1.1')
print(my_list)
```

Accepted Answer

['192.168.1.10', '255.255.255.0', '192.168.1.1']. The printed output is a list containing three string elements: '192.168.1.10', '255.255.255.0', and '192.168.1.1'. When printing a list in Python, it displays each element enclosed in square brackets and separated by commas. Option C correctly shows this output. The other options have an incorrect number of elements.

Answer

['255.255.255.0']

Answer

['192.168.1.10']

Answer

['192.168.1.10', '192.168.1.1']

Question 15

A developer needs to determine the number of elements in a tuple named 't'. Which code snippet will correctly return the length?

Accepted Answer

len(t). The correct way to determine the number of elements in a tuple in Python is to use the built-in `len()` function, which returns the length (number of items) of any sequence or collection, including tuples. Option C is correct because `len(t)` directly gives the count of elements in tuple `t`.

Answer

t.append(5)

Answer

t[0] = 5

Answer

t.pop()

Question 16

A programmer writes: result = 'Py' * 2 + 'thon'. What is the value of result?

Accepted Answer

'Python'. In Python, the * operator on a string repeats it, and the + operator concatenates strings. 'Py' * 2 produces 'PyPy', then 'PyPy' + 'thon' results in 'Python'. This follows Python's operator precedence where * has higher precedence than +, so the multiplication is evaluated first.

Answer

'Py2thon'

Answer

'Pyththon'

Answer

'PyPy'

Question 17

A developer writes a function that modifies a global variable inside the function:

count = 0
def increment():
    count += 1

When called, an error occurs. What is the correct way to fix this?

Accepted Answer

Use 'global count' inside the function. The error occurs because Python treats 'count' as a local variable inside the function due to the assignment, but it is referenced before assignment. Using 'global count' inside the function explicitly tells Python to use the global variable, allowing modification. This is the correct fix for modifying a global variable from within a function.

Answer

Define count inside the function

Answer

Use the 'static' keyword

Answer

Pass count as an argument to the function

Question 18

A company needs to filter a list of temperatures in Celsius to only those above 0, then convert to Fahrenheit (multiply by 9/5 and add 32). Which code snippet correctly accomplishes this using a list comprehension?

Accepted Answer

[t*9/5+32 for t in temps if t>0]. It uses the standard list comprehension syntax: `[expression for item in iterable if condition]`. Here, `t*9/5+32` is the expression that converts Celsius to Fahrenheit, `for t in temps` iterates over the list, and `if t>0` filters out temperatures at or below zero. This produces a new list containing only the Fahrenheit equivalents of positive Celsius temperatures.

Answer

[t for t in temps if t>0 then t*9/5+32]

Answer

[t*9/5+32 for t in temps if t>0 else 0]

Answer

[t*9/5+32 for t in temps if t>0 else t]

Question 19

A programmer is reviewing code that uses loops and conditional statements. Which TWO of the following statements about Python control flow are correct? (Choose two.)

Accepted Answer

An if statement can be nested inside a for loop, and a for loop can be nested inside an if statement.. The two correct statements are that a for loop's else runs only without a break, and that control structures can be nested arbitrarily. These reflect Python's actual semantics. The other statements mischaracterize continue, break, and while loop behavior, each of which is well-defined and different from the described behavior.

Answer

A while loop always executes its body at least once, even if the condition is initially false.

Answer

The break statement can be used outside a loop to terminate the program.

Answer

The continue statement exits the current loop entirely and resumes execution after the loop.

Question 20

Consider the following code:

def foo(x, y):
    return x * y

result = foo(y=2, 3)

What is the error?

Accepted Answer

A positional argument follows a keyword argument.. In Python, when calling a function, all positional arguments must appear before any keyword arguments. The call `foo(y=2, 3)` violates this rule by placing a positional argument (`3`) after a keyword argument (`y=2`), which raises a SyntaxError. This is enforced by Python's parser to avoid ambiguity in argument binding.

Answer

The function requires at least one argument but none provided.

Answer

Keyword arguments cannot be used in function calls.

Answer

The function definition has too many parameters.