11_conditional_statements.py

#======================================================================================
#                               CONDITIONAL STATEMENTS
#--------------------------------------------------------------------------------------
# A conditional statement lets python make decisions.
# If condition is true, do this--otherwise do something else.
# In simple words it a checkpoint that checks a condition is True or False.
#======================================================================================

#--------------------------------------------------------------------------------------
# 1) simple if statement
#--------------------------------------------------------------------------------------
#   Defines the first condition
#   if the condition is true, do this
#   otherwise, do nothing
#--------------------------------------------------------------------------------------
#--------------------------------------------------------------------------------------
# if rules
#--------------------------------------------------------------------------------------
#   --only one if 
#   --starts with if
#   --it is required not optional
#   --can standalone
#-------------------------------------------------------------------------------------

# without indentation
#score = 100
#if score >= 90:
#print("A") throws an error

#-------------------------------------------------------------------------------------
# Indentation
#-------------------------------------------------------------------------------------
# adding spaces at the beginning of a line to show the line
# belongs to a code block
#-------------------------------------------------------------------------------------


score = 100
if score >= 90:
    print("A")

#--------------------------------------------------------------------------------------
# 3) if-else statement
#--------------------------------------------------------------------------------------
#   runs only if all previous conditions are false
#   if nothing was true, do this instead
#--------------------------------------------------------------------------------------
#--------------------------------------------------------------------------------------
# else rules
#--------------------------------------------------------------------------------------
#   --comes at the end
#   --no conditions
#   --its optional
#   --cannot standalone
#   --only one else
#-------------------------------------------------------------------------------------
score = 50
if score >= 90:
    print("A")
else:
    print("F")

#--------------------------------------------------------------------------------------
# 3) if-elif-else statement
#--------------------------------------------------------------------------------------
#   asks a follow-up question
#   only runs if previous conditions were false
#   if the first wasn't true, try this one
#--------------------------------------------------------------------------------------
#--------------------------------------------------------------------------------------
# elif rules
#--------------------------------------------------------------------------------------
#   --comes after if
#   --multiple elif
#   --needs condition
#   --optional
#   --cannot standalone
#-------------------------------------------------------------------------------------
score = 80
if score >= 90:
    print("A")
elif score >= 80:
    print("B")
else:
    print("F")


#--------------------------------------------------------------------------------------
# Full grading logic with multiple elif
#--------------------------------------------------------------------------------------
score = 60
if score >= 90:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
elif score >= 60:
    print("D")
else:
    print("F")

#--------------------------------------------------------------------------------------
# Nested if 
#--------------------------------------------------------------------------------------
# if statement inside another if statement
#--------------------------------------------------------------------------------------
score = 90
submitted_project = True
if score >= 90:
    if submitted_project:
        print("A+")
    else:
        print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
elif score >= 60:
    print("D")
else:
    print("F")

#--------------------------------------------------------------------------------------
# Combined statements with logical operators and/or
#--------------------------------------------------------------------------------------
score = 10
submitted_project = True
if score >= 90 and submitted_project:
    print("A+")
elif score >= 90:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
elif score >= 60 or submitted_project:
    print("D")
else:
    print("F")

#--------------------------------------------------------------------------------------
# Independent conditions
#--------------------------------------------------------------------------------------

score = 80
submitted_project = True

if score >= 90:
    print("High Score")
else:
    print("Low Score")

if submitted_project:
    print("Project is Submitted")
else:
    print("Project is not Submitted")

#--------------------------------------------------------------------------------------
# #1 Challenge
# validate the quality and correctness of email values
#--------------------------------------------------------------------------------------
# --Email must not be empty
# --Email must contain "." and "@"
# --Email must contain exactly one "@" symbol
# --Email must end with ".com", ".org", ".net"
# --Email must not be longer than 254 characters
# --Email must start and end with a letter or digit
#--------------------------------------------------------------------------------------
email = "munna@gmail.com"
email = email.strip()

# --Email must not be empty
if email == "":
    print("Email cannot be empty.")
# --Email must contain "." and "@"
elif not ("." in email and "@" in email):
    print("Email must contain \".\" and \"@\" symbol.")
# --Email must contain exactly one "@" symbol
elif email.count("@") != 1:
    print("Email must contain exactly one \"@\" symbol")
# --Email must end with ".com", ".org", ".net"
elif not email.endswith((".com", ".org", ".net")):
    print("Email must end with .com, .org, or .net")
# --Email must not be longer than 254 characters
elif len(email) > 254:
    print("Email must not be longer than 254 characters")
# --Email must start and end with a letter or digit
elif not (email[0].isalnum() and email[-1].isalnum()): # isalnum()--checks if the string contains only letters and digits
    print("Email must start and end with a letter or digit")
else:
    print("Valid Email")


#--------------------------------------------------------------------------------------
# #2 Challenge
# validate the quality and correctness of passwords
#--------------------------------------------------------------------------------------
# --Password must not be empty
# --Password must be at least 8 characters
# --Password include at least 1 uppercase
# --Password include at least 1 lowercase
# --Password must not be same as email
# --Password must not contain any spaces
# --Password must start and end with a letter or digit
#--------------------------------------------------------------------------------------
password = "David@Wilson"
# --Password must not be empty
if password == "":
    print("password cannot be empty")
# --Password must be at least 8 characters
elif len(password) <= 8:
    print("password must be at least 8 characters")
# --Password include at least 1 uppercase
elif not any((char.isupper() for char in password)):
    print("password must include at least 1 uppercase letter")
# --Password include at least 1 lowercase
elif not any(char.islower() for char in password):
    print("password must include at least 1 lowercase letter")
# --Password must not be same as email
elif password == email:
    print("password must not be same as email")
# --Password must not contain any spaces
elif " " in password:
    print("password must not contain spaces")
# --Password must start and end with a letter or digit
elif not (password[0].isalnum() and password[-1].isalnum()):
    print("Password must start and end with a letter or digit")
else:
    print("Valid password")


#--------------------------------------------------------------------------------------
# Normal if statement    |   inline if statement(ternary operator)
#--------------------------------------------------------------------------------------
# if condition1:         |   do A if condition1 else do B
#   do A                 |
# else:                  |
#   do B                 |
##--------------------------------------------------------------------------------------
#--------------------------------------------------------------------------------------
# Simple Logic  (Use inline if for simple logic only)
#--------------------------------------------------------------------------------------
score = 90
print("A" if score >= 90 else "F")
# we can also assign the output of if statement to a variable
grade = "A" if score >= 90 else "F"
print(grade)


#--------------------------------------------------------------------------------------
# Complex Logic (for complex conditions, normal if blocks are  clearer.)
#--------------------------------------------------------------------------------------
# inline-if statement(nested ternary) --> it hurts readability
grade ="A" if score >= 90 else "B" if score >= 80 else "C" if score >= 70 else "D" if score >= 60 else "F"
print(grade)
# Normal if statement --> easy to read
if score >= 90:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
elif score >= 60:
    print("D")
else:
    print("F")
#--------------------------------------------------------------------------------------
# Task
# Convert the full country names into 2-letter abbreviations
#--------------------------------------------------------------------------------------

country = "United States"
if  country == "United States":
    print("US")
elif country == "India":
    print("IN")
elif country == "Egypt":
    print("EG")
elif country == "Germany":
    print("DE")
else:
    print("Unknown Country")
#--------------------------------------------------------------------------------------
# MATCH-CASE
#--------------------------------------------------------------------------------------
# match-case is used to compare a value against multiple patterns
# and execute the matching block.
#--------------------------------------------------------------------------------------
# match-case rules
#--------------------------------------------------------------------------------------
# works only in python 3.10+
# _ (under score) is mandatory for default case(recommended)
# do not works on complex conditions(x > 10 and x < 20)
#--------------------------------------------------------------------------------------
country = "Am"
match country:
    case "United States" | "USA" |"America":
        print("US")
    case "India"  | "Bharat":
        print("IN")
    case "Egypt":
        print("EG")
    case "Germany":
        print("DE")
    case _:
        print("Unknown Country")