Python · Quick Reference

Lesson 3 — Strings & Text Cheat Sheet

Python

In one line: A string is a sequence of characters — letters, digits, spaces, symbols, or even emojis — wrapped in quotes. Strings are one of the most used data types in any programming langu...

Key Ideas

1What is a String?. A string is a sequence of characters — letters, digits, spaces, symbols, or even emojis — wrapped in quotes. Strings are one of the most used data types in any program...

2Indexing & Slicing. Every character in a string has a position number called an index. Python indexes start at 0 (not 1!). You can also count from the end using negative indexes — -1 is a...

3Essential String Methods. Python strings come with 50+ built-in methods. You call them with dot notation: string.method(). Here are the most important ones you'll use daily.

4f-Strings — Modern String Formatting. An f-string (formatted string literal) is the modern, clean way to embed variables and expressions directly inside a string. Prefix the string with f and put variables...

5Escape Characters. Some characters can't be typed directly inside a string — like a newline, a tab, or a backslash. You use an escape sequence: a backslash \ followed by a special charac...

Code Examples

# Three ways to create strings
single  = 'Hello, Python!'       # single quotes
double  = "Hello, Python!"       # double quotes (same result)
triple  = """This string
spans multiple
lines."""                          # triple quotes = multi-line

print(sin...

lang = "Python"

# Positive indexing
print(lang[0])   # P  — first character
print(lang[1])   # y
print(lang[5])   # n  — last character

# Negative indexing
print(lang[-1])  # n  — last character
print(lang[-6])  # P  — first character

# IndexError — goin...

text = "BitWithBite"

# Basic slice: [start:stop]  (stop is excluded)
print(text[0:3])    # Bit  (chars at 0,1,2)
print(text[3:7])    # With
print(text[7:])     # Bite  (omit stop = go to end)
print(text[:3])     # Bit   (omit start = from beginning)
print(...