Variables

In Python, a variable is a named storage location that holds data, which can be modified during the execution of the program. Variables are used to store values for later use and are created when a value is assigned to them using the assignment operator (=).

Variables

Key Concepts of Variables in Python

Variable Assignment: Variables are assigned using the = operator. The variable name is on the left side and the value on the right side of the operator.
```
x = 5  # Assigns the value 5 to the variable x
name = "Francesco"  # Assigns the string "Francesco" to the variable name
```
Dynamic Typing: Python is dynamically typed, meaning that variables do not need an explicit type declaration. The type of the variable is inferred from the value assigned to it.
```
x = 5  # Integer
x = "Hello"  # Now x is a string
```
Variable Naming: Variable names must follow these rules:
- Begin with a letter or an underscore (_).
- Followed by letters, digits, or underscores.
- Case-sensitive (e.g., variable, Variable, and VARIABLE are different).
```
my_var = 10
_private_var = 20
variable1 = 30
```

Variable Scope: Variables have different scopes:

Local Scope: Variables defined within a function.
Global Scope: Variables defined outside any function or class.

global_var = "I am global"

def my_function():
    local_var = "I am local"
    print(global_var)  # Access global variable
    print(local_var)   # Access local variable

Reassignment: Variables can be reassigned to new values of any type.

my_var = 10
my_var = "Now I am a string"  # Reassignment to a string

Multiple Assignments: You can assign a single value to multiple variables or multiple values to multiple variables in a single line.
```
a = b = c = 5  # Assigns 5 to a, b, and c
x, y, z = 1, 2, 3  # Assigns 1 to x, 2 to y, and 3 to z
```
Data Types: Variables can hold different types of data, including but not limited to integers, floats, strings, lists, tuples, and dictionaries.
```
my_list = [1, 2, 3]  # List
my_tuple = (4, 5, 6)  # Tuple
my_dict = {"key1": "value1", "key2": "value2"}  # Dictionary
```
Variable Deletion: Variables can be deleted using the del statement, which removes the variable and its value from memory.
```
x = 10
del x  # x is deleted and accessing it will raise an error
```

Type Conversion: You can convert variables from one type to another using type conversion functions like int(), float(), str(), etc.

x = "123"
y = int(x)  # Converts the string "123" to the integer 123
z = float(y)  # Converts the integer 123 to the float 123.0

Constants: Python does not have built-in constant types, but by convention, variables intended to be constants are written in uppercase.
```
PI = 3.14159  # Conventionally a constant
```

Notes about Python

Variables

Key Concepts of Variables in Python