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PCAP-31-03: What Does dir(sys) Return in Python String or List?

By: Author Alex Lim

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Explore Python’s sys module and understand the return types of dir(sys) and sys.path[-1]. Learn how to correctly evaluate boolean expressions in Python for PCAP-31-03 certification.

Table of Contents

Question

What is the expected output of the following code?

import sys

b1 type (dir(sys)) is str
b2 type (sys.path[-1]) is str
print (b1 and b2)

A. True
B. False
C. 0
D. None

Answer

The expected output of the given code is:

B. False

Explanation

Let’s break down the code and explain why:

1. import sys
This line imports the sys module, which provides access to some variables and functions used or maintained by the Python interpreter.

2. b1 = type(dir(sys)) is str

  • dir(sys) returns a list of names in the sys module.
  • type(dir(sys)) returns <class ‘list’>.
  • The expression type(dir(sys)) is str compares <class ‘list’> with <class ‘str’>.
  • Since these are different types, b1 will be False.

3. b2 = type(sys.path[-1]) is str

  • sys.path is a list of strings that specifies the search path for modules.
  • sys.path[-1] accesses the last element of this list, which is a string.
  • type(sys.path[-1]) returns <class ‘str’>.
  • The expression type(sys.path[-1]) is str compares <class ‘str’> with <class ‘str’>.
  • Since these are the same type, b2 will be True.

4. print(b1 and b2)

  • This performs a logical AND operation between b1 (False) and b2 (True).
  • In Python, False and True evaluates to False.

Therefore, the final output of the code will be False.

This question tests your understanding of:

  1. The sys module and its components
  2. The dir() function and its return type
  3. The type() function and type comparisons
  4. Boolean operations in Python
  5. List indexing (specifically, accessing the last element with [-1])

Understanding these concepts is crucial for the PCAP-31-03 certification exam, as they cover fundamental Python programming knowledge and the use of built-in functions and modules.

Python Institute PCAP-31-03 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Python Institute PCAP-31-03 exam and earn Python Institute PCAP-31-03 certification.