strings.py

"""
String Exercises - Complete the functions below
Run this file with: python topic.py
Or work interactively with: python3 -i topic.py
"""

# Exercise 1: Basic String Operations
def get_length(text):
    """Return the length of a string."""
    # Your code here
    pass

def to_upper_case(text):
    """Convert a string to uppercase."""
    # Your code here
    pass

def to_lower_case(text):
    """Convert a string to lowercase."""
    # Your code here
    pass

# Exercise 2: String Analysis
def count_vowels(text):
    """Count vowels (a, e, i, o, u) in a string (case insensitive)."""
    # Your code here
    pass

def count_words(text):
    """Count words in a string (separated by spaces)."""
    # Your code here
    pass

def is_palindrome(text):
    """Check if a string reads the same forwards and backwards (ignore case and spaces)."""
    # Your code here
    pass

# Exercise 3: String Searching
def find_substring(text, substring):
    """Return the index of the first occurrence of substring, -1 if not found."""
    # Your code here
    pass

def count_occurrences(text, substring):
    """Count how many times substring appears in text."""
    # Your code here
    pass

def starts_with_prefix(text, prefix):
    """Check if text starts with prefix."""
    # Your code here
    pass

# Exercise 4: String Modification
def remove_spaces(text):
    """Remove all spaces from a string."""
    # Your code here
    pass

def replace_char(text, old_char, new_char):
    """Replace all occurrences of old_char with new_char."""
    # Your code here
    pass

def reverse_string(text):
    """Return the string reversed."""
    # Your code here
    pass

# Exercise 5: String Formatting
def format_name(first, last):
    """Create name in 'Last, First' format."""
    # Your code here
    pass

def create_email(username, domain):
    """Create an email address: username@domain."""
    # Your code here
    pass

def format_phone(area_code, exchange, number):
    """Format phone as '(area_code) exchange-number'."""
    # Your code here
    pass

# Exercise 6: String Validation
def is_valid_email(email):
    """Check basic email format (contains @ and .)."""
    # Your code here
    pass

def is_all_digits(text):
    """Check if string contains only digits."""
    # Your code here
    pass

def is_strong_password(password):
    """Check if password has uppercase, lowercase, and digits."""
    # Your code here
    pass

# Exercise 7: String Parsing
def extract_numbers(text):
    """Extract all numbers from a string and return them as a list of integers."""
    # Your code here
    pass

def split_csv_line(line):
    """Split a CSV line into a list of values."""
    # Your code here
    pass

def parse_name(full_name):
    """Split 'First Last' into a tuple (first, last)."""
    # Your code here
    pass

# Exercise 8: String Lists
def join_with_comma(string_list):
    """Join strings with commas."""
    # Your code here
    pass

def longest_string(string_list):
    """Find the longest string in a list."""
    # Your code here
    pass

def filter_by_length(string_list, min_length):
    """Filter strings by minimum length."""
    # Your code here
    pass

# Exercise 9: Advanced String Processing
def title_case(text):
    """Convert to title case (capitalize each word)."""
    # Your code here
    pass

def remove_duplicates(text):
    """Remove duplicate characters while preserving order."""
    # Your code here
    pass

def compress_string(text):
    """Compress 'aabbbcccc' to 'a2b3c4'."""
    # Your code here
    pass

def run_tests():
    """Test all the functions to verify they work correctly."""
    print("Testing Basic String Operations:")
    print(f"Length of 'hello': {get_length('hello')}")           # Should print 5
    print(f"'hello' uppercase: {to_upper_case('hello')}")        # Should print HELLO
    print(f"'WORLD' lowercase: {to_lower_case('WORLD')}")        # Should print world

    print("\nTesting String Analysis:")
    print(f"Vowels in 'hello world': {count_vowels('hello world')}")  # Should print 3
    print(f"Words in 'hello world': {count_words('hello world')}")     # Should print 2
    print(f"Is 'racecar' palindrome: {is_palindrome('racecar')}")      # Should print True
    print(f"Is 'hello' palindrome: {is_palindrome('hello')}")          # Should print False

    print("\nTesting String Searching:")
    print(f"'ell' in 'hello': {find_substring('hello', 'ell')}")       # Should print 1
    print(f"'xyz' in 'hello': {find_substring('hello', 'xyz')}")       # Should print -1
    print(f"Count 'll' in 'hello': {count_occurrences('hello', 'll')}") # Should print 1
    print(f"'hello' starts with 'he': {starts_with_prefix('hello', 'he')}") # Should print True

    print("\nTesting String Modification:")
    print(f"Remove spaces from 'he llo wo rld': {remove_spaces('he llo wo rld')}")  # Should print helloworld
    print(f"Replace 'l' with 'x' in 'hello': {replace_char('hello', 'l', 'x')}")    # Should print hexxo
    print(f"Reverse 'hello': {reverse_string('hello')}")                            # Should print olleh

    print("\nTesting String Formatting:")
    print(f"Format name: {format_name('John', 'Doe')}")                 # Should print Doe, John
    print(f"Create email: {create_email('john', 'example.com')}")       # Should print john@example.com
    print(f"Format phone: {format_phone('555', '123', '4567')}")        # Should print (555) 123-4567

    print("\nTesting String Validation:")
    print(f"Valid email 'test@email.com': {is_valid_email('test@email.com')}")  # Should print True
    print(f"Valid email 'invalid': {is_valid_email('invalid')}")                # Should print False
    print(f"All digits '12345': {is_all_digits('12345')}")                      # Should print True
    print(f"All digits 'abc123': {is_all_digits('abc123')}")                    # Should print False
    print(f"Strong password 'Pass123': {is_strong_password('Pass123')}")        # Should print True

    print("\nTesting String Parsing:")
    print(f"Extract numbers: {extract_numbers('I have 5 cats and 3 dogs')}")    # Should print [5, 3]
    print(f"Split CSV: {split_csv_line('apple,banana,cherry')}")                # Should print ['apple', 'banana', 'cherry']
    print(f"Parse name: {parse_name('John Doe')}")                              # Should print ('John', 'Doe')

    print("\nTesting String Lists:")
    print(f"Join with comma: {join_with_comma(['apple', 'banana'])}")           # Should print apple,banana
    print(f"Longest string: {longest_string(['hi', 'hello', 'hey'])}")         # Should print hello
    print(f"Filter by length 4: {filter_by_length(['hi', 'hello', 'hey'], 4)}")  # Should print ['hello']

    print("\nTesting Advanced Processing:")
    print(f"Title case: {title_case('hello world')}")                          # Should print Hello World
    print(f"Remove duplicates: {remove_duplicates('aabbcc')}")                 # Should print abc
    print(f"Compress string: {compress_string('aabbbcccc')}")                  # Should print a2b3c4

if __name__ == "__main__":
    print("Python String Exercises")
    print("=" * 40)
    print("Complete the functions above, then run this file to test them.")
    print("Uncomment the line below when you're ready to test:")
    print()
    # run_tests()  # Uncomment this line to run tests