var_names # snake_case
CONSTANT_VAR # UPPERCASE
 
ClassNames # PascalCase
_protected_class_attribute # single underscore
__private_class_attribute # double underscore

name = "Alice"  # string (text)
age = 25        # int    (whole nums)
height = 5.5    # float  (decimal nums)
is_true = True  # bool   (True/False)
fruits = ["apple", "banana"]  # list
person = { "name": "Alice", "age": 25 }  # dict

x = 5
type(x) # int

fruits = ["apple", "banana"]
fruits[0] # get
fruits.append("cherry")  # add
fruits.remove("banana")  # remove
for fruit in fruits:  # loop
    print(fruit)

person = { "name": "Alice", "age": 25 }
person["name"]  # get
person["city"] = "New York"  # add
person.pop("age", None)  # remove
for key, value in person.items():  # loop
    print(key, value)

username = "Alex"
print("Welcome " + username) # Welcome Alex

name = "Bob"
print(f"Thanks {name}") # Thanks Bob

name = input("Name: ")
height = int(input("Height: "))

if temperature > 75:
    print("Hot!")
elif temperature < 60:
    print("Cold!")
else:
    print("Mild")

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit) # apple, banana, cherry
 
for i in range(5):
    print(i)  # 0, 1, 2, 3, 4
 
for index, fruit in enumerate(fruits):
    print(index, fruit) # 0 apple, 1 banana, 2 cherry

while condition:
  print("condition is True")

for i in range(10):
    if i == 5:
        break # exits out of loop
    print(i)  # 0, 1, 2, 3, 4
 
for i in range(5):
    if i == 2:
        continue # skips to next iteration
    print(i)  # 0, 1, 3, 4

==  # equal to
!=  # not equal to
>   # greater than
<   # less than
>=  # greater or equal
<=  # less or equal

if x > 0 and x < 10:
    print("x is between 0 and 10")
 
if x < 0 or x > 10:
    print("Outside range")
 
is_valid = not False

def add(a, b):
    return a + b
 
result = add(5, 3)
print(result) # 8

def area(width, height): # positional args
    return width * height
 
area(5, 6)  # must be passed in order
 
def area(width=5, height=5): # default args
    return width * height
 
area()  # default arg values 5, 5 are used
area(height=6, width=5)  # keyword args can be passed in any order
 
def area(*args):  # arbitrary args
    return args[0] * args[1]
 
area(5, 6)  # can pass any number of args
area(5, 6, 7, 8) # args[2] and args[3] are unused
 
def area(**kwargs):  # arbitrary keyword args
    return kwargs["width"] * kwargs["height"]
 
area(height=6, width=5)  # can pass any number of keyword args in any order
area(width=5, potatos='round', height=6) # potatoes is unused

len("Hello")        # length
type(123)           # type check
int("42")           # convert to int
float("3.14")       # convert to float
str(123)            # convert to string
round(3.14159, 2)   # round
sum([1, 2, 3])      # sum

x = 10  # global var
what_scope = "global"
 
def outer():
    y = 20  # enclosing var
    what_scope = "enclosing"
 
    def inner():
        z = 30  # local var
        what_scope = "local"
        print(x, y, z)  # can access all higher scopes
        print(what_scope)  # local
 
    inner()
    print(x, y)  # z doesnt exist in enclosing scope
    print(what_scope)  # enclosing
 
outer()
print(x)  # y and z dont exist in global scope
print(what_scope)  # global

global_count = 0 # global var
 
def outer():
    enclosing_count = 0  # enclosing var
 
    global global_count  # modifies global var
    global_count += 1
 
    def inner():
        nonlocal enclosing_count
        enclosing_count += 1  # modifies enclosing var
 
    inner()
    print(enclosing_count)  # 1
 
outer()
print(global_count)  # 1

from math import sqrt  # import a function
from random import *   # import all functions

try:
    # code that might raise an error
    raise Exception("Error!")
except Exception as e:
    print(e)

file = open("file.txt", "r")  # open file in read mode
content = file.read()  # read file content
file.close()  # close file