Strings in Python

Defining Strings in Python

Strings are defined using single (' ') or double (" ") quotes and are of type str. For multi-line text, triple quotes (''' ''' or """ """) can be used.

Strings are immutable, meaning their contents cannot be changed after creation.


my_str = "Python"
print(type(my_str))  # Output: <class 'str'>

Core Features of Strings

Indexing: Access individual characters by position.
Slicing: Extract specific portions using start:end syntax.
Length: Use len() to count characters.
Repetition: Use * to repeat strings.
Concatenation: Use + to join strings.

Examples:


text = "Python"
print(text[0])           # Output: 'P'
print(text[1:4])         # Output: 'yth'
print(len(text))         # Output: 6
print(text * 2)          # Output: 'PythonPython'
print(text + " Rocks!")  # Output: 'Python Rocks!'

Common String Methods

Method	Description
`str.lower()`	Converts all characters to lowercase
`str.upper()`	Converts all characters to uppercase
`str.strip()`	Removes whitespace or specified characters from both ends
`str.replace(old, new)`	Replaces occurrences of a substring
`str.find(sub)`	Finds index of first occurrence of a substring
`str.split(delimiter)`	Splits string into list based on delimiter
`str.join(list)`	Joins list elements into a string using a separator
`str.startswith(prefix)`	Checks if string starts with specified prefix
`str.endswith(suffix)`	Checks if string ends with specified suffix
`str.isdigit()`	Returns True if string contains only digits

Usage Examples:


text = "  Python is Fun!  "

print(text.strip())                      # Removes leading/trailing spaces
print(text.lower())                      # Converts to lowercase
print(text.find("is"))                   # Output: 9
print(text.replace("Fun", "Powerful"))   # Replaces substring
print(text.split())                      # Output: ['Python', 'is', 'Fun!']
print("-".join(["A", "B", "C"]))         # Output: 'A-B-C'
print(text.startswith("Py"))            # False due to leading spaces
print("123".isdigit())                   # Output: True

Conclusion

Strings in Python are versatile and essential for text-based operations. From slicing and joining to formatting and condition checks, mastering string manipulation helps you write clean, expressive, and efficient Python code.