Python Fundamentals Quiz

Introduction to Objects and Classes in Python

• Objects consist of related data (value) and functions that manipulate that data (methods).

• In Python, almost everything is an object, including integers, strings, floats, and booleans.

• Dates are part of the datetime module in Python, and creating a new date object involves using the date() function.

• A class is a template from which objects are instantiated, while an object describes a particular instance of that class.

• Creating a custom class involves defining its attributes and methods, and a constructor function called init is used to initialize its instance variables.

• Instance variables are variables attached to an object instance, and can be accessed and modified using dot notation.

• Methods are functions attached to an object that can accept arguments and modify instance variables.

• Immutable objects, such as integers and strings, cannot have their value changed, and new objects are created to represent the result in computations.

• Mutable objects, such as custom classes, can be changed and will affect all variables that reference that object.

• In Python, variables reference objects stored in memory, and assignment changes which object a variable references.

• Objects with no references become inaccessible and are automatically removed from memory by Python.

• The is keyword can be used to check whether two variables reference the same object.Python Objects and Strings

• Objects combine data and behavior, and can be defined using classes.

• Instantiating multiple objects of the same class will result in different object instances occupying different locations in memory.

• Mutating one object will not affect the other.

• String literals can be expressed using single or double quotes, and escape sequences can be used to include special characters.

• Alternative ways of expressing string literals include using double quotes or triple quotes for multiline strings.

• A string is a sequence of characters that can be indexed and sliced to retrieve specific characters or substrings.

• The length of a string can be obtained using the len() function.

• The find() and rfind() methods can be used to search for substrings within a string.

• Comparing strings is case-sensitive, but case can be ignored by converting all letters to either lowercase or uppercase.

• The replace() method can be used to replace parts of a string with a specified replacement.

• String manipulation can be performed using for loops, conditional statements, and built-in string methods.

• In the next lecture, we will explore how to create and manipulate strings using f-strings and perform file system operations.Python Strings and Files

• Python provides escape sequences to include characters in strings that can't be written in a straightforward way.

• Different ways of writing string literals in Python include single quotes, double quotes, and triple quotes.

• String manipulation can be done using various built-in string methods.

• F-strings are a convenient way of building strings in Python.

• F-strings reduce the need for string concatenation using the + operator and str() function.

• Format specifiers can be added to an f-string to specify how values are formatted.

• Format specifiers can be used to specify the number of decimal places, width, and alignment of values in an f-string.

• A text file is a file that contains human-readable characters and can be edited in a program like Notepad.

• Binary files do not fundamentally represent their data using human-readable characters.

• Opening a file in Python requires the use of the built-in open() function.

• A file object represents a file in Python and provides methods for reading and writing data.

• The read() method of a file object can be used to read the entire content of a file as a string.Working with Files in Python

• Reading large files at once can be slow or may not fit in memory, so reading line-by-line is a better option.

• The readline method allows reading one line at a time and advances the cursor position in the file.

• Each line includes the newline character at the end, which can be removed using string slicing or replacement.

• The seek method can be used to return the cursor position to the beginning of the file for reading the same lines multiple times.

• Python allows using a file object in a for loop, treating it like a sequence of lines.

• Writing to a file requires opening it in a file mode that allows writing, such as 'w', and using the write method.

• Appending text to an existing file can be done using the file mode 'a' instead of 'w', which erases the file contents.

• The os module provides functions for working with file system paths, identifying paths as files or directories, creating directories, listing directory entries, renaming files/directories, and removing files/directories.

• Absolute paths are fully qualified and globally unique, while relative paths are relative to the current directory.

• The default file mode when opening a file is 'r', which allows reading but not writing.

• Including newline characters (\n) is necessary when writing to a file to indicate new lines.

• When using readline, calling read twice in a row on the same file object returns the entire contents of the file as a string and then an empty string.