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21. Working with Strings

1. Introduction​

Strings are one of the most commonly used data types in Python.
They represent sequences of characters and are used for storing text.

2. Creating Strings​

Strings can be created with single quotes, double quotes, or triple quotes:

s1 = 'Hello'
s2 = "World"
s3 = """This is
a multi-line string."""

3. Accessing Characters​

Strings are sequences, so you can access characters using indexes:

word = "Python"
print(word[0])   # P
print(word[-1])  # n (last character)

4. String Slicing​

You can extract substrings using slices:

word = "Python"
print(word[0:3])   # Pyt
print(word[2:])    # thon
print(word[:4])    # Pyth
print(word[-3:])   # hon

5. Common String Operations​

  • Concatenation:
print("Hello " + "World")  # Hello World
  • Repetition:
print("Hi! " * 3)  # Hi! Hi! Hi!
  • Length:
print(len("Python"))  # 6

6. Useful String Methods​

text = "  python programming  "

print(text.upper())    # "  PYTHON PROGRAMMING  "
print(text.lower())    # "  python programming  "
print(text.strip())    # "python programming"
print(text.replace("python", "java"))  # "  java programming  "
print(text.split())    # ['python', 'programming']
print("-".join(["a", "b", "c"]))       # "a-b-c"

7. String Searching​

sentence = "Learning Python is fun"
print("Python" in sentence)     # True
print(sentence.find("Python"))  # 9 (index where found)

8. Escape Sequences​

Special characters can be written with a backslash:

print("Line1\nLine2")   # newline
print("Hello\tWorld")   # tab
print("She said \"Hi\"") # quotes inside string

9. f-Strings (String Interpolation)​

Introduced in Python 3.6+, f-strings allow inserting variables directly:

name = "Alice"
age = 25
print(f"My name is {name} and I am {age} years old.")

10. Raw Strings​

Useful for paths and regular expressions:

path = r"C:\Users\Name\Documents"
print(path)  # C:\Users\Name\Documents

11. Next Steps​

✅ You now know how to work with strings: indexing, slicing, methods, and formatting.
In the next chapter, we’ll cover escape characters and raw strings in more detail.