Python string
Table of Contents
Description
A string in Python is a sequence of characters enclosed in single quotes ' ', double quotes " ", or triple quotes ''' ''' / """ """ for multi-line strings. Strings are immutable, meaning once created, they cannot be changed. Python provides a rich set of methods for string manipulation, including slicing, formatting, and searching.
Prerequisites
- Basic understanding of variables
- Knowledge of indexing and loops helps in string manipulation.
Examples
Here's a simple program in Python:
# String declaration
s1 = "Hello"
s2 = 'World'
s3 = """This is a
multi-line string."""
# Concatenation
full = s1 + " " + s2 # Result: "Hello World"
# Accessing characters
print(s1[0]) # Output: 'H' (indexing starts from 0)
# Slicing
print(s1[1:4]) # Output: 'ell' (characters from index 1 to 3)
# String methods
print(s1.upper()) # Output: 'HELLO'
print(s2.lower()) # Output: 'world'
print(s1.replace("H", "J")) # Output: 'Jello'
# Checking substring
print("lo" in s1) # Output: True
# Length of a string
print(len(s1)) # Output: 5
Real-World Applications
Processing text data (e.g., chatbots, NLP).
Reading and manipulating files (file names, extensions)
Building dynamic messages and logs.
Web scraping, parsing HTML/XML content.
Form validation (email, username, passwords).
Where topic Can Be Applied
Natural Language Processing (NLP): Tokenizing and analyzing sentences.
Web development: Handling form inputs, URLs, HTML tags.
File handling: Managing file paths and contents.
Data cleaning: Formatting and correcting data entries.
Automation scripts: Generating dynamic commands or messages.
Resources
Topic video source
A comprehensive video
Watch
Python pdf
pdf on topic
Visit
Interview Questions
What is a string in Python?
How do you declare multi-line strings?
What is string immutability? Can you modify a string in-place?
How does slicing work in strings?
Name five string methods and explain what they do.