Python Institute PCEP - Certified Entry-Level Python Programmer PCEP-30-02 Exam Questions

Answer : D

The code snippet that you have sent is a while loop with an if statement and a print statement inside it. The code is as follows:

while True: if counter < 0: print('''') else: print(''**'')

The code starts with entering a while loop that repeats indefinitely, because the condition ''True'' is always true. Inside the loop, the code checks if the value of ''counter'' is less than 0. If yes, it prints a single asterisk () to the screen. If no, it prints three asterisks (**) to the screen. However, the code does not change the value of ''counter'' inside the loop, so the same condition is checked over and over again. The loop never ends, and the code enters an infinite loop.

The program outputs either one asterisk () or three asterisks (**) to the screen repeatedly, depending on the initial value of ''counter''. Therefore, the correct answer is D. The program enters an infinite loop.

Answer : A

The code snippet that you have sent is trying to use the global keyword to access and modify a global variable inside a function. The code is as follows:

speed = 10 def velocity(): global speed speed = speed + 10 return speed

print(velocity())

The code starts with creating a global variable called ''speed'' and assigning it the value 10. A global variable is a variable that is defined outside any function and can be accessed by any part of the code. Then, the code defines a function called ''velocity'' that takes no parameters and returns the value of ''speed'' after adding 10 to it. Inside the function, the code uses the global keyword to declare that it wants to use the global variable ''speed'', not a local one. A local variable is a variable that is defined inside a function and can only be accessed by that function. The global keyword allows the function to modify the global variable, not just read it. Then, the code adds 10 to the value of ''speed'' and returns it. Finally, the code calls the function ''velocity'' and prints the result.

However, the code has a problem. The problem is that the code uses the global keyword inside the function, but not outside. The global keyword is only needed when you want to modify a global variable inside a function, not when you want to create or access it outside a function. If you use the global keyword outside a function, you will get a SyntaxError exception, which is an error that occurs when the code does not follow the rules of the Python language. The code does not handle the exception, and therefore it will terminate with an error message.

The expected result of the code is an unhandled exception, because the code uses the global keyword incorrectly. Therefore, the correct answer is A. The code is erroneous and cannot be run.

The code is erroneous because it is trying to call the ''velocity'' function without passing any parameter, which will raise aTypeErrorexception. The ''velocity'' function requires one parameter ''x'', which is used to calculate the return value of ''speed'' multiplied by ''x''. If no parameter is passed, the function will not know what value to use for ''x''.

The code is also erroneous because it is trying to use the ''new_speed'' variable before it is defined. The ''new_speed'' variable is assigned the value of 20 after the first function call, but it is used as a parameter for the second function call, which will raise aNameErrorexception. The variable should be defined before it is used in any expression or function call.

Therefore, the code will not run and will not produce any output.

The correct way to write the code would be:

# Define the speed variable

speed = 10

# Define the velocity function

def velocity(x):

return speed * x

# Define the new_speed variable

new_speed = 20

# Call the velocity function with new_speed as a parameter

print(velocity(new_speed))

Copy

This code will print 200, which is the result of 10 multiplied by 20.

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[Python: Built-in Exceptions]

[Python: Defining Functions]

[Python: More on Variables and Printing]

Answer : A, B

In Python, the ** operator is used for exponentiation, the / operator is used for floating-point division, and the // operator is used for integer division. The order of operations is parentheses, exponentiation, multiplication/division, and addition/subtraction. Therefore, the expressions can be evaluated as follows:

A) 2 ** 3 / A - 2 = 8 / A - 2 (assuming A is a variable that is not zero or undefined) B. 4 / 2 * * 3 - 2 = 4 / 8 - 2 = 0.5 - 2 = -1.5 C. 1 * * 3 / 4 - 1 = 1 / 4 - 1 = 0.25 - 1 = -0.75 D. 1 * 4 // 2 ** 3 = 4 // 8 = 0

Only expressions A and B evaluate to non-zero results.

Answer : C

The code snippet that you have sent is a loop that checks if a variable ''floor'' is less than or equal to 0 and prints a string accordingly. The code is as follows:

floor = 5 while floor > 0: print(''+'') floor = floor - 1

The code starts with assigning the value 5 to the variable ''floor''. Then, it enters a while loop that repeats as long as the condition ''floor > 0'' is true. Inside the loop, the code prints a ''+'' symbol to the screen, and then subtracts 1 from the value of ''floor''. The loop ends when ''floor'' becomes 0 or negative, and the code exits.

The code outputs five ''+'' symbols to the screen, one for each iteration of the loop. Therefore, the correct answer is C. five.

Answer : D

The code snippet that you have sent is trying to print the combined length of two lists, ''collection'' and ''duplicate''. The code is as follows:

collection = [] collection.append(1) collection.insert(0, 2) duplicate = collection duplicate.append(3) print(len(collection) + len(duplicate))

The code starts with creating an empty list called ''collection'' and appending the number 1 to it. The list now contains [1]. Then, the code inserts the number 2 at the beginning of the list. The list now contains [2, 1]. Then, the code creates a new list called ''duplicate'' and assigns it the value of ''collection''. However, this does not create a copy of the list, but rather a reference to the same list object. Therefore, any changes made to ''duplicate'' will also affect ''collection'', and vice versa. Then, the code appends the number 3 to ''duplicate''. The list now contains [2, 1, 3], and so does ''collection''. Finally, the code tries to print the sum of the lengths of ''collection'' and ''duplicate''. However, this causes an exception, because the len function expects a single argument, not two. The code does not handle the exception, and therefore outputs nothing.

The expected output of the code is nothing, because the code raises an exception and terminates. Therefore, the correct answer is D. The code raises an exception and outputs nothing.

Answer : D

The code snippet that you have sent is defining and calling a function in Python. The code is as follows:

def runner(brand, model, year): return (brand, model, year)

print(runner(''Fermi''))

The code starts with defining a function called ''runner'' with three parameters: ''brand'', ''model'', and ''year''. The function returns a tuple with the values of the parameters. A tuple is a data type in Python that can store multiple values in an ordered and immutable way. A tuple is created by using parentheses and separating the values with commas. For example, (1, 2, 3) is a tuple with three values.

Then, the code calls the function ''runner'' with the value ''Fermi'' for the ''brand'' parameter and prints the result. However, the function expects three arguments, but only one is given. This will cause a TypeError exception, which is an error that occurs when a function or operation receives an argument that has the wrong type or number. The code does not handle the exception, and therefore it will terminate with an error message.

However, if the code had handled the exception, or if the function had used default values for the missing parameters, the expected output of the code would be ('Fermi ', '2021', 'False'). This is because the function returns a tuple with the values of the parameters, and the print function displays the tuple to the screen. Therefore, the correct answer is D. ('Fermi ', '2021', 'False').

Answer : A, C

Exceptions and debugging are two important concepts in Python programming that are related to handling and preventing errors. Exceptions are errors that occur when the code cannot be executed properly, such as syntax errors, type errors, index errors, etc. Debugging is the process of finding and fixing errors in the code, using various tools and techniques. Some of the facts about exceptions and debugging are:

A tool that allows you to precisely trace program execution is called a debugger. A debugger is a program that can run another program step by step, inspect the values of variables, set breakpoints, evaluate expressions, etc. A debugger can help you find the source and cause of an error, and test possible solutions. Python has a built-in debugger module called pdb, which can be used from the command line or within the code.There are also other third-party debuggers available for Python, such as PyCharm, Visual Studio Code, etc12

If some Python code is executed without errors, this does not prove that there are no errors in it. It only means that the code did not encounter any exceptions that would stop the execution. However, the code may still have logical errors, which are errors that cause the code to produce incorrect or unexpected results. For example, if you write a function that is supposed to calculate the area of a circle, but you use the wrong formula, the code may run without errors, but it will give you the wrong answer. Logical errors are harder to detect and debug than syntax or runtime errors, because they do not generate any error messages.You have to test the code with different inputs and outputs, and compare them with the expected results34

One try-except block may contain more than one except branch. A try-except block is a way of handling exceptions in Python, by using the keywords try and except. The try block contains the code that may raise an exception, and the except block contains the code that will execute if an exception occurs. You can have multiple except blocks for different types of exceptions, or for different actions to take. For example, you can write a try-except block like this:

try: # some code that may raise an exception except ValueError: # handle the ValueError exception except ZeroDivisionError: # handle the ZeroDivisionError exception except: # handle any other exception

This way, you can customize the error handling for different situations, and provide more informative messages or alternative solutions5

The default (anonymous) except branch can be the last branch in the try-except block. The default except branch is the one that does not specify any exception type, and it will catch any exception that is not handled by the previous except branches. The default except branch can be the last branch in the try-except block, but it cannot be the first or the only branch. For example, you can write a try-except block like this:

try: # some code that may raise an exception except ValueError: # handle the ValueError exception except: # handle any other exception

This is a valid try-except block, and the default except branch will be the last branch. However, you cannot write a try-except block like this:

try: # some code that may raise an exception except: # handle any exception

This is an invalid try-except block, because the default except branch is the only branch, and it will catch all exceptions, even those that are not errors, such as KeyboardInterrupt or SystemExit. This is considered a bad practice, because it may hide or ignore important exceptions that should be handled differently or propagated further.Therefore, you should always specify the exception types that you want to handle, and use the default except branch only as a last resort5

Therefore, the correct answers are A. A tool that allows you to precisely trace program execution is called a debugger. and C. One try-except block may contain more than one except branch.