Python Interview Questions and Answers- Part 2

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Python is a high-level, interpreted, and general-purpose programming language known for its simplicity and readability. Its key features include a large standard library, dynamic typing, automatic memory management, and support for multiple programming paradigms.

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Python 3 introduced several backward-incompatible changes and new features compared to Python 2. Some key differences include improved Unicode support, better syntax, enhanced standard library modules, and the requirement to use parentheses for print statements in Python 3.

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The Global Interpreter Lock (GIL) is a mechanism in CPython (the reference implementation of Python) that permits only one thread to execute Python bytecode at a time. It means that multiple threads in a Python program cannot fully utilize multiple CPU cores. However, the GIL simplifies memory management and makes it easier to develop and debug Python code.

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Exceptions in Python can be handled using the try, except, else, and finally statements. Code that may raise an exception is placed inside a try block, and if an exception occurs, the corresponding except block catches it. The else block is executed if no exception occurs, and the finally block is always executed, whether an exception occurs or not.

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Decorators are tools used to modify the behavior of functions or classes without changing their source code. They use the @decorator_name syntax and can be applied to functions or classes. Decorators wrap the original function or class, allowing additional code to be executed before or after the original code runs. They are often used for tasks like logging, authentication, and memorization.

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In Python, a shallow copy creates a new object that references the original object’s memory. Changes made to the original object may be reflected in the shallow copy. In contrast, a deep copy creates a new object with its own memory space, copying all nested objects recursively. Changes done to the original object does not affect the deep copy.

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File I/O operations in Python can be performed using the open() function. You can use the read() or readlines() methods to read from a file. Similarly, to write to a file, you can use the write() method. It’s important to close the file using the close() method or by utilizing the with statement, which automatically closes the file when done.

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Python provides various profiling tools such as cProfile and line_profiler to measure the performance of code. Optimizations can be achieved by identifying bottlenecks and making changes like using efficient algorithms, avoiding unnecessary computations, and utilizing built-in functions and data structures.

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Errors and exceptions can be handled using the try and except statements. The code that might raise an exception is placed in the try block, and if an exception occurs, it is caught and handled in the corresponding except block. Multiple except blocks can be used to handle diverse exceptions types.

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The pass statement is a placeholder statement in Python that does nothing. It is used when a statement is essential syntactically but no action is needed. It is commonly used as a placeholder in empty functions, classes, or loops.

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A module is a file holding Python code that defines functions, classes, and variables. It allows code reusability and organization. Modules can be imported and used in other Python scripts using the import statement. Python provides a vast collection of standard modules, and users can create their own custom modules.

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You can use the get() method or the defaultdict class from the collections module to handle missing keys in a dictionary,. The get() method returns the value for a given key, and if the key is not found, it returns a default value. The defaultdict is a subclass of the dictionary that automatically assigns a default value to missing keys.

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Lists and sets are both collection types in Python, but they have key differences. Lists are ordered and allow duplicate elements, while sets are unordered and do not allow duplicate elements. Lists are defined using square brackets ([]), while sets are defined using curly braces ({}).

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Name mangling is a mechanism in Python that adds a prefix of double underscores (__) to class attributes to avoid name clashes between subclasses. It is primarily used to make an attribute “private” within a class, even though Python does not enforce true privacy. Name-mangled attributes are accessible using the _ClassName__attribute syntax.

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Python has a default recursion depth limit, which means that recursive functions cannot exceed a certain number of nested calls. To handle recursion depth errors, you can either optimize the algorithm to reduce the number of recursive calls or increase the recursion limit using the sys.setrecursionlimit() function. However, increasing the recursion limit has its limitations and may lead to stack overflow errors.

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The is operator checks if two variables refer to the same object in memory. On the other hand, the == operator checks if the values of two variables are equal.

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Circular imports happen when two or more modules depend on each other. To handle circular imports, you can restructure the code to remove the circular dependency or import the required modules inside functions or methods where they are actually used.

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The yield keyword is used in the definition of generator functions. It allows the function to return a value and temporarily suspend its execution. The function can then be resumed later, and the state of the function is preserved.

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Metaclasses are classes that define the behavior of other classes. They act as blueprints for creating classes. By defining a metaclass, you can customize the creation, behavior, and attributes of classes. Metaclasses are a powerful but advanced feature of Python, and they are not commonly used in everyday programming.

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Exceptions in Python can be handled using try, except, else, and finally blocks. You can catch specific exceptions using except blocks, and you can also raise your own exceptions using the raise statement.