10_logical_operators.py

#======================================================================================
#                               LOGICAL OPERATORS
#--------------------------------------------------------------------------------------
# logical operators are used to combine multiple boolean expressions
#   1) and 
#   2) or 
#   3) not
#   4) in
#   5) not in
#--------------------------------------------------------------------------------------
#======================================================================================

#--------------------------------------------------------------------------------------
# 1) and--returns True if all conditions are True
#--------------------------------------------------------------------------------------
print(3 > 1 and 5 < 1)
print(3 > 1 and 5 > 1)

email = True
password = True
print(email and password)

#--------------------------------------------------------------------------------------
# 2) or --returns True if any one condition is True
#--------------------------------------------------------------------------------------
print(3 > 1 or 5 < 1)
print(3 < 1 or 5 < 1)

cpu_usage = 70
storage_usage = 50
print(cpu_usage >= 70 or storage_usage > 90)

#--------------------------------------------------------------------------------------
# 3) not--reverses the result(True<-->False)
#--------------------------------------------------------------------------------------
print(not 3 > 1)
print(not True)
print(not False)

name = ""
print(not name)
print(not 0)
print(not None)

#--------------------------------------------------------------------------------------
# execution order parentheses() first
#--------------------------------------------------------------------------------------
x = 5
y = 8
z = 6
print(x == 5 or y > 5 and z <4)     # "and" has higher priority than "or"
print((x == 5 or y > 5) and z < 4)    # use parentheses() to control the order

#--------------------------------------------------------------------------------------
#Exercise
# Allow access only if the user is logged in
# or they are a guest
# but they must not be banned
#--------------------------------------------------------------------------------------
is_logged_in = True
is_guest = False
is_banned = True

print((is_logged_in or is_guest) and not is_banned)

#======================================================================================
# python challenge
#--------------------------------------------------------------------------------------
#1) checks if a user's name is not empty and the age is greater than or equal to 18
#--------------------------------------------------------------------------------------
username = "David"
age = 19
if username and age >= 18:
    print("Valid User")
else:
    print("Invalid User")

#--------------------------------------------------------------------------------------
#2) check if the password is at least 8 characters long and does not contain spaces
#--------------------------------------------------------------------------------------
password = "Charlie2580"
if len(password) >= 8 and not " " in password:
    print("Valid Password")
else:
    print("Invalid Password")

#--------------------------------------------------------------------------------------
#3) check if a user's email is not empty, contains '@' and ends with '.com'
#--------------------------------------------------------------------------------------
email = "shaikmunna@gmail.com"
if email and "@" in email and email.endswith(".com"):
    print("Valid email")
else:
    print("Invalid email")

#--------------------------------------------------------------------------------------
#4) check if a username is a string, is not None, and is longer than 5 characters
#--------------------------------------------------------------------------------------
username = ""
if isinstance(username, str) and username is not None and len(username) > 5:
    print("Valid username")
else:
    print("Invalid username")

#--------------------------------------------------------------------------------------
#5) check if the user is either an admin or a moderator, and
#   either they're not banned or they've verified their email
#--------------------------------------------------------------------------------------
role = "admin".lower()
is_banned = False
verified_email = True
if (role == "admin" or role == "moderator") and (not is_banned or verified_email):
    print("Access granted")
else:
    print("Access denied")


#======================================================================================
#                               MEMBERSHIP OPERATORS
#--------------------------------------------------------------------------------------
# Membership operators are used to check whether a value exists inside a collection
# (like string, list, tuple, set, dictionary).
#======================================================================================
#----------------------------------------
# operator    |  meaning                |
#----------------------------------------
#   in        |  value exists           |
#   not in    |  value does not exist   |
#----------------------------------------
print("o" in "python")      #True
print("f" in "python")      #False
print("f" not in "python")  #True

# Task
# Security check: ensure the domain is not banned
domain = "spam.com" 
banned_domains = ["spam.com", "fake.org", "bot.net"]
print(domain not in banned_domains) # False

#======================================================================================
#                               IDENTITY OPERATORS
#--------------------------------------------------------------------------------------
# Identity operators are used to check whether two variables point to the same object
# in memory, NOT whether their values are equal.
#======================================================================================

#----------------------------------------
# operator    |  meaning                |
#----------------------------------------
#   is        |  Same object            |
#   is not    |  different object       |
#----------------------------------------
a = 10
b = 10
print(a == b)   # True(same value)
print(a is b)   # True(same memory for small integers) 

x = [1,2,3]
y = [1,2,3]
print(x == y)   # True(same values)
print(x is y)   # False(different memory)

k = [1,2,3]
l = k
print(k == l)   # True
print(k is l)   # True

#--------------------------------------------------------------------------------------
# Task: Make sure the email exists, and it's not empty.
#--------------------------------------------------------------------------------------
email = "mun@gmail.com"
print(email is not None and email != "")    # use "is/is not" instead of "==/!=" when checking for None