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Measuring String Length

  • The len() function in Python allows us to find the length of a string
  • Use '.length' in JavaScript to do this as well


    • print(len("Hello"))

    5


    String Case Convertion

  • Uppercase: Convert to uppercase using .upper() in Python, .toUpperCase() in JS
  • Lowercase: Convert to lowercase using .lower() in Python, .toLowerCase() in JS


    • print("hello".upper())
print("HELLO".lower())

    HELLO
hello


    String Slicing

  • Through string slicing, we can access a part of the string using indexes
  • Each character in a string gets assigned a index, starting from 0
  • Syntax in Python is [startindex:endindex]
  • Syntax in JS is .slice(startindex, endindex)


    • print("Hello Brawler"[0:5])

    Hello

    Finding Substrings

  • Searches for a substring and returns its position within a overlaying string
  • .find() in Python
  • .indexOf() in JS

    • print("Hello Brawler".find("Brawler"))

    6


    Replacing Substrings

  • Can replace different parts of a string with something else
  • .replace() in Python and JS


    • print("Hello Brawler".replace("Brawler", "Mihir"))

    Hello Mihir


    Splitting Strings

  • Splits a string into a list of substrings based on a delimiter (most commonly a space or comma)
  • .split() in Python and JS


    • print("Darryl,Mico,Fang".split(","))

    ['Darryl', 'Mico', 'Fang']


    Splitting Strings

  • Basically opposite of splitting strings
  • .join() in Python and JS


    • print(",".join(['Darryl', 'Mico', 'Fang']))

    Darryl,Mico,Fang

    Sample Hack - String Analyzation

    • Determine metrics about strings (length, chars, palidrome(?), etc.)
    string = "Brawl Stars is a fun game!"
string2 = "Star Brawl war Brats"
print("String 1: Brawl Stars is a fun game!")
length = len(string)
print("Length:", length)
def count_vowels(input_string):
    vowels = 'aeiouAEIOU'
    count = 0
    for char in input_string:
        if char in vowels:
            count += 1
    return count
print("Vowel Count:", count_vowels(string))
def average_word_length(input_string):
    words = input_string.split()
    if not words:
        return 0
    total_length = sum(len(word) for word in words)
    average_length = total_length / len(words)
    return average_length
print("Average Word Count:", average_word_length(string))
def palindrome(input_string):
    string = input_string.replace(" ","").lower()
    return string == string[::-1]
print("Palindrome or Not?", palindrome(string))
print("String 2: Star Brawl war Brats")
length2 = len(string2)
print("Length:", length2)
print("Vowel Count:", count_vowels(string2))
print("Average Word Count:", average_word_length(string2))
print("Palindrome or Not?", palindrome(string2))

    String 1: Brawl Stars is a fun game!
Length: 26
Vowel Count: 7
Average Word Count: 3.5
Palindrome or Not? False
String 2: Star Brawl war Brats
Length: 20
Vowel Count: 4
Average Word Count: 4.25
Palindrome or Not? True

    Sample Hack - Password Validator

    The goal of this homework hack is to create a password validator. A couple examples are given below (Simple and Advanced)

    Simple Password Validator

    def password_validator(password):
    if len(password) < 8:
        return "Password too short. Must be at least 8 characters."

    if password == password.lower() or password == password.upper():
        return "Password must contain both uppercase and lowercase letters."

    if not any(char.isdigit() for char in password):
        return "Password must contain at least one number."

    # Optional
    password = password.replace("123", "abc")

    words = password.split(" ")
    customized_password = "-".join(words)

    return f"Password is valid! Here’s a fun version: {customized_password}"

# Example usage
password = "HelloWorld123"
print(password_validator(password))


    Password is valid! Here’s a fun version: HelloWorldabc

    print(password_validator("HELLO123"))

    Password must contain both uppercase and lowercase letters.

    print(password_validator("Hello123"))

    Password is valid! Here’s a fun version: Helloabc

    Advanced Password Validator

    import re

def password_validator(password):
    if len(password) < 8:
        return "Password too short. Must be at least 8 characters."
    
    if password == password.lower() or password == password.upper():
        return "Password must contain both uppercase and lowercase letters."
    
    if not any(char.isdigit() for char in password):
        return "Password must contain at least one number."
    
    if not re.search(r"[!@#$%^&*()_+]", password):
        return "Password must contain at least one special character (e.g. !, @, #, etc.)"
    
    common_passwords = ["password", "123456", "letmein", "qwerty"]
    if password.lower() in common_passwords:
        return "Password is too common. Choose something less predictable."
    
    sequential_patterns = ["123", "abc", "xyz"]
    for pattern in sequential_patterns:
        if pattern in password.lower():
            return "Password should not contain sequential characters like '123' or 'abc'."
    
    score = 0
    if len(password) >= 10:
        score += 1
    if re.search(r"[A-Z]", password) and re.search(r"[a-z]", password):
        score += 1
    if re.search(r"\d", password):
        score += 1
    if re.search(r"[!@#$%^&*()_+]", password):
        score += 1

    strength = "Weak"
    if score == 2:
        strength = "Medium"
    elif score >= 3:
        strength = "Strong"

    password = password.replace("Hello", "Hi")
    words = password.split(" ")
    customized_password = "-".join(words)

    return f"Password is valid and {strength}! Here’s a fun version: {customized_password}"

# Example usage
password = "HelloWorld13475!"
print(password_validator(password))



    Password is valid and Strong! Here’s a fun version: HiWorld13475!