# Single quotes
name = 'Alice'
message = 'Hello, world!'

# Double quotes
title = "Python Programming"
quote = "She said, 'Hello there!'"

# Triple quotes (multiline strings)
poem = """Roses are red,
Violets are blue,
Python is awesome,
And so are you!"""

multiline = '''This is a
multiline string
that spans several lines.'''

# Raw strings (useful for file paths and regex)
file_path = r"C:UsersAliceDocumentsile.txt"
regex_pattern = r"d+.d+"

# Unicode strings (Python 3.x default)
greeting = "Hello 世界! 🐍"
symbols = "α β γ δ ε"

print(f"Name: {name}")           # Alice
print(f"Quote: {quote}")         # She said, 'Hello there!'
print(f"Greeting: {greeting}")   # Hello 世界! 🐍
print(poem)                      # Prints the multiline poem

text = "Python"

# Positive indexing (0-based)
print(text[0])    # 'P' (first character)
print(text[1])    # 'y' (second character)
print(text[5])    # 'n' (last character)

# Negative indexing (from the end)
print(text[-1])   # 'n' (last character)
print(text[-2])   # 'o' (second to last)
print(text[-6])   # 'P' (first character)

# String slicing [start:end:step]
word = "Programming"

print(word[0:4])     # 'Prog' (characters 0 to 3)
print(word[4:])      # 'ramming' (from index 4 to end)
print(word[:4])      # 'Prog' (from start to index 3)
print(word[::2])     # 'Pormig' (every 2nd character)
print(word[::-1])    # 'gnimmargorP' (reverse string)

# Advanced slicing
sentence = "Hello, Python World!"
print(sentence[7:13])    # 'Python' (extract specific word)
print(sentence[::3])     # 'Hl,Ph ol!' (every 3rd character)
print(sentence[-6:-1])   # 'World' (slice from end)

# Using + operator
first_name = "John"
last_name = "Doe"
full_name = first_name + " " + last_name
print(full_name)  # "John Doe"

# Using += for building strings
message = "Hello"
message += " "
message += "World"
print(message)    # "Hello World"

# Using join() for multiple strings (most efficient)
words = ["Python", "is", "awesome"]
sentence = " ".join(words)
print(sentence)   # "Python is awesome"

# Joining with different separators
fruits = ["apple", "banana", "cherry"]
print(", ".join(fruits))     # "apple, banana, cherry"
print(" | ".join(fruits))    # "apple | banana | cherry"
print("".join(fruits))       # "applebananacherry"

# Multiplying strings
laugh = "ha" * 3
print(laugh)      # "hahaha"

border = "-" * 20
print(border)     # "--------------------"

# Combining different approaches
greeting = "Welcome" + " " + "to " * 2 + "Python!"
print(greeting)   # "Welcome to to Python!"

# F-strings (Python 3.6+) - Recommended
name = "Alice"
age = 30
height = 5.6

# Basic f-string formatting
intro = f"My name is {{name}} and I am {{age}} years old."
print(intro)  # "My name is Alice and I am 30 years old."

# Expressions in f-strings
print(f"Next year I'll be {{age + 1}}")  # "Next year I'll be 31"
print(f"My height is {{height:.1f}} feet")  # "My height is 5.6 feet"

# Formatting numbers
price = 19.99
quantity = 3
total = price * quantity

print(f"Price: ${{price:.2f}}")           # "Price: $19.99"
print(f"Total: ${{total:.2f}}")           # "Total: $59.97"
print(f"Quantity: {{quantity:03d}}")      # "Quantity: 003"

# .format() method (older but still useful)
template = "Hello, {{}}! You have {{}} messages."
message = template.format("Bob", 5)
print(message)  # "Hello, Bob! You have 5 messages."

# Named placeholders
info = "Name: {{name}}, Age: {{age}}".format(name="Charlie", age=25)
print(info)  # "Name: Charlie, Age: 25"

# % formatting (oldest, rarely used now)
old_style = "Hello, %s! You are %d years old." % ("David", 28)
print(old_style)  # "Hello, David! You are 28 years old."

# Advanced f-string formatting
from datetime import datetime
now = datetime.now()
print(f"Current time: {{now:%Y-%m-%d %H:%M:%S}}")  # "Current time: 2024-01-15 10:30:45"

# Debugging with f-strings (Python 3.8+)
x = 10
y = 20
print(f"{{x + y = }}")  # "x + y = 30" (shows both expression and result)

# Common escape characters
print("Hello
World")        # 
 = newline
print("Hello	World")        # 	 = tab
print("Hello\nWorld")       # \ = literal backslash
print("She said, "Hello!"") # " = double quote
print('It's a beautiful day') # ' = single quote

# More escape characters
print("Bell sound: a")      # a = bell/alert (may not be audible)
print("Backspace: abcd")   #  = backspace
print("Form feed: ")       #  = form feed
print("Carriage return: abc
def") # 
 = carriage return
print("Vertical tab: ")    #  = vertical tab

# Unicode escape sequences
print("A")              # \u = Unicode (4 digits): 'A'
print("U00000041")          # U = Unicode (8 digits): 'A'
print("N{LATIN CAPITAL LETTER A}")  # N = Unicode name: 'A'

# Raw strings ignore escape characters
normal_string = "C:
ew	ext.txt"    # 
 and 	 are interpreted as escapes!
raw_string = r"C:
ew	ext.txt"      # Raw string preserves backslashes
print(f"Normal: {repr(normal_string)}")  # Shows the escape interpretation
print(f"Raw: {raw_string}")              # C:
ew	ext.txt

# Triple quotes can contain quotes without escaping
text = """He said, "Python is great!"
She replied, 'I totally agree!'"""
print(text)

# Strings are immutable
original = "Hello"
# original[0] = "h"  # This would cause an error!

# Instead, create a new string
modified = "h" + original[1:]
print(f"Original: {original}")  # "Hello"
print(f"Modified: {modified}")  # "hello"

# String length
message = "Python Programming"
print(f"Length: {len(message)}")  # 18

# Check if string contains substring
text = "I love Python programming"
print("Python" in text)          # True
print("Java" in text)            # False
print("python" in text)          # False (case-sensitive)
print("python" in text.lower())  # True (case-insensitive check)

# String comparison
word1 = "apple"
word2 = "banana"
print(word1 < word2)             # True (alphabetical order)
print("A" < "a")                 # True (uppercase before lowercase)

# Empty strings
empty1 = ""
empty2 = str()
print(f"Empty string length: {len(empty1)}")  # 0
print(f"Is empty: {not empty1}")               # True

# String iteration
word = "Python"
for char in word:
    print(char, end=" ")  # P y t h o n 
print()

# String repetition and membership
repeated = "abc" * 3
print(repeated)                   # "abcabcabc"
print("ab" in repeated)           # True
print("xyz" not in repeated)      # True

# String memory efficiency
text1 = "Hello"
text2 = "Hello"
print(text1 is text2)            # Often True (string interning)
print(id(text1) == id(text2))    # Often True (same memory location)