Python Naming Conventions and Variable Handling

Naming Conventions

• Camel Case: Every word except the first starts with a capital letter, like userName
• Pascal Case: Every word starts with a capital letter, like UserName
• Snake Case: Each word is separated by an underscore, like user_name

Assigning Values to Multiple Variables

• You can assign values to multiple variables in a single line, ensuring the number of variables matches the number of values.

Unpacking Collections

• Python lets you extract values from a list, tuple, etc., into variables. This is called unpacking.
• For example, fruit = ["apple", "banana", "cherry"], x, y, z = fruit will assign apple to x, banana to y, and cherry to z.

Outputting Variables

• The print() function is used to display values, including variables.
• Use commas to separate multiple variables in the print() function.
• You can also use the + operator to combine strings and variables in print(), but be mindful of spaces and data types.
• Avoid using + with strings and numbers to prevent errors.

Global Variables

• Variables created outside functions are called global variables and can be accessed anywhere.
• Variables defined inside functions are local and only accessible within that function.
• If you use the same variable name inside and outside a function, the function will work with a local variable, leaving the global variable unchanged.
• The global keyword declares a variable inside a function as a global variable, allowing modification of the global variable.

Data Types

• Python uses built-in data types to store different kinds of data.
• Use the type() function to determine the data type of an object.
• The data type is automatically assigned when you give a variable a value.
• You can explicitly specify data types using constructor functions: int(), float(), str(), and bool().

Lists

• Store multiple items in a single variable, using square brackets [].
• Ordered, changeable, and allow duplicate values.
• Items are indexed, starting from 0 for the first item.
• Use the len() function to find the number of items.
• Items can be of any data type.
• You can use the list() constructor to create a list.
• Use the type() function to determine the data type of each element in a list (for mixed data types).

Accessing List Items

• Access items using their index number.
• Use a colon : to specify a range of indexes.
• Negative indexes start from the end of the list (-1 for the last item).
• Use the in keyword to check if an item exists in a list.

Removing List Items

• remove() method removes the first occurrence of a specified item.
• pop() method removes the item at a specified index, or the last item if no index is given.
• del keyword removes items at a specified index or removes the entire list.
• clear() empties the list, but the list object still remains.

Looping through Lists

• Use a for loop to iterate over each item in a list.
• Use a while loop with the len() function and index to iterate through list items.

Joining Lists

• Use the + operator to concatenate lists.
• Use the append() method to add items from one list to another one by one.
• Use the extend() method to add all items from one list to another list.

List Methods

• append(): Adds an element to the end of the list.
• insert(): Inserts an element at a specific index.
• remove(): Removes the first occurrence of a specified element.
• pop(): Removes the element at a specified index, or the last element if no index is given.
• clear(): Removes all elements from the list.
• index(): Returns the index of the first occurrence of a specified element.
• count(): Returns the number of occurrences of a specified element.
• sort(): Sorts the list in ascending order.
• reverse(): Reverses the order of the elements in the list.
• copy(): Returns a copy of the list.

Tuples

• Store multiple items in a single variable, using parentheses ().
• Ordered and unchangeable (cannot be modified after creation).
• Items are indexed, starting from 0 for the first item.
• Allow duplicate values.
• Use the len() function to find the number of items.
• Items can be of any data type.
• You can use the tuple() constructor to create a tuple.

Python Collections

• Lists: ordered, changeable, allow duplicates.
• Tuples: ordered, unchangeable, allow duplicates.
• Sets: unordered, unchangeable, unindexed, do not allow duplicates.
• Dictionaries: ordered, changeable, do not allow duplicate keys.

Test your knowledge on Python naming conventions, variable assignments, and unpacking collections. This quiz covers essential practices in Python programming that every developer should know. Identify the correct methods and syntax to effectively manage variables in your code.