strings.md

Python by Example: Strings

Strings are immutable sequences of Unicode characters. You can index and slice them like lists. Python provides many string methods for common tasks: split, join, strip, upper, lower, replace, and more. Strings are used everywhere—user input, file content, API responses.

What you'll learn:

• Indexing and slicing strings
• Common methods: split, join, strip, upper, lower, replace

s = "Hello, World!"

# Indexing and slicing
print(s[0])
print(s[-1])
print(s[7:12])

# Common methods
print(s.lower())
print(s.upper())
print(s.replace("World", "Python"))

# split and join
words = "a b c".split()
print(words)
print("-".join(words))

# strip whitespace
print("  hello  ".strip())

split() with no argument splits on whitespace. join() is the inverse—it combines a list of strings with the separator. Strings are immutable; methods return new strings.

To run this program:

$ python source/strings.py
H
!
World
hello, world!
HELLO, WORLD!
Hello, Python!
['a', 'b', 'c']
a-b-c
hello

Tip: "".join(list_of_strings) is faster than concatenating with + in a loop when building a string.

Try it: Use split() and join() to reverse the words in a sentence.

Source: strings.py

Next: String Formatting