Built-in String Methods in Python

Python provides a rich set of built-in string methods for manipulating and working with text data. These methods cover everything from case conversion and formatting to searching and validation.

Case Conversion Methods

Methods for changing the case of characters in strings ?

text = "hello WORLD"

print("Original:", text)
print("capitalize():", text.capitalize())
print("upper():", text.upper())
print("lower():", text.lower())
print("title():", text.title())
print("swapcase():", text.swapcase())

Original: hello WORLD
capitalize(): Hello world
upper(): HELLO WORLD
lower(): hello world
title(): Hello World
swapcase(): HELLO world

String Validation Methods

Methods that return True or False based on string content ?

text1 = "Hello123"
text2 = "hello"
text3 = "123"
text4 = "   "

print("isalnum():", text1.isalnum())  # Letters and numbers
print("isalpha():", text2.isalpha())  # Only letters
print("isdigit():", text3.isdigit())  # Only digits
print("isspace():", text4.isspace())  # Only whitespace
print("islower():", text2.islower())  # Lowercase letters
print("isupper():", "HELLO".isupper())  # Uppercase letters

isalnum(): True
isalpha(): True
isdigit(): True
isspace(): True
islower(): True
isupper(): True

Search and Replace Methods

Methods for finding and replacing text within strings ?

text = "Python is great. Python is powerful."

print("find('Python'):", text.find("Python"))
print("count('Python'):", text.count("Python"))
print("replace('Python', 'Java'):", text.replace("Python", "Java"))
print("startswith('Python'):", text.startswith("Python"))
print("endswith('powerful.'):", text.endswith("powerful."))

find('Python'): 0
count('Python'): 2
replace('Python', 'Java'): Java is great. Java is powerful.
startswith('Python'): True
endswith('powerful.'): True

String Formatting and Padding

Methods for formatting and aligning strings ?

text = "Python"

print("center(20, '*'):", text.center(20, '*'))
print("ljust(15, '-'):", text.ljust(15, '-'))
print("rjust(15, '-'):", text.rjust(15, '-'))
print("zfill(10):", "42".zfill(10))

center(20, '*'): *******Python*******
ljust(15, '-'): Python---------
rjust(15, '-'): ---------Python
zfill(10): 0000000042

String Splitting and Joining

Methods for breaking strings apart and combining them ?

text = "apple,banana,cherry"
words = ["Python", "is", "awesome"]

print("split(','):", text.split(','))
print("join with ' ':", ' '.join(words))
print("splitlines():", "Line1\nLine2\nLine3".splitlines())

split(','): ['apple', 'banana', 'cherry']
join with ' ': Python is awesome
splitlines(): ['Line1', 'Line2', 'Line3']

String Cleaning Methods

Methods for removing unwanted characters ?

text = "   Hello World   "

print("Original:", repr(text))
print("strip():", repr(text.strip()))
print("lstrip():", repr(text.lstrip()))
print("rstrip():", repr(text.rstrip()))

Original: '   Hello World   '
strip(): 'Hello World'
lstrip(): 'Hello World   '
rstrip(): '   Hello World'

Complete Methods Reference

Conclusion

Python's built-in string methods provide comprehensive functionality for text manipulation. These methods are essential for string processing tasks like validation, formatting, searching, and transformation in Python applications.