Strings are one of the most commonly used data types in Python. Whether you're reading user input, processing text data, or working with files, you'll be using strings a lot.
In this article, you'll learn everything about Python strings, including:
-
What they are
-
How to create and manipulate them
-
String methods
-
Formatting techniques
-
Tips and common mistakes
What is a String?
A string is a sequence of characters enclosed in quotes.
✅ You can use:
-
Single quotes
' ' -
Double quotes
" " -
Triple quotes
''' '''or""" """(for multi-line strings)
Example:
name = "Alice"
message = 'Hello, World!'
paragraph = """This is a
multi-line string."""
Accessing Characters in a String
Strings are indexed, starting from 0. You can access individual characters using brackets:
name = "Python"
print(name[0]) # Output: P
print(name[-1]) # Output: n (last character)
String Slicing
You can extract parts of a string using slicing:
s = "Hello, World!"
print(s[0:5]) # Output: Hello
print(s[:5]) # Output: Hello (start is optional)
print(s[7:]) # Output: World!
print(s[-6:-1]) # Output: World
Syntax: string[start:stop] (stop index is excluded)
➕ String Concatenation and Repetition
Concatenation:
first = "Hello"
last = "World"
print(first + " " + last) # Output: Hello World
Repetition:
print("Ha" * 3) # Output: HaHaHa
Looping Through Strings
word = "Python"
for char in word:
print(char)
String Methods (Built-in Functions)
Python provides many helpful string methods:
| Method | Description | Example |
|---|---|---|
.lower() |
Converts to lowercase | "HELLO".lower() → "hello" |
.upper() |
Converts to uppercase | "hi".upper() → "HI" |
.strip() |
Removes whitespace | " hi ".strip() → "hi" |
.replace(a, b) |
Replace substring | "Hello".replace("l", "x") → "Hexxo" |
.split() |
Splits string into list | "a,b,c".split(",") → ["a", "b", "c"] |
.join() |
Joins list into string | "-".join(["a", "b", "c"]) → "a-b-c" |
.find() |
Returns first index of substring | "hello".find("e") → 1 |
.startswith() |
Checks prefix | "hello".startswith("he") → True |
.endswith() |
Checks suffix | "hello".endswith("o") → True |
String Formatting
1. f-strings (Recommended, Python 3.6+)
name = "Alice"
age = 30
print(f"My name is {name} and I am {age} years old.")
2. str.format() method
print("My name is {} and I am {} years old.".format(name, age))
3. % formatting (old style)
print("My name is %s and I am %d years old." % (name, age))
Example: Word Reversal Tool
text = input("Enter a word: ")
reversed_text = text[::-1]
print(f"The reversed word is: {reversed_text}")
String Length
Use len() to get the number of characters:
s = "Python"
print(len(s)) # Output: 6
Escape Characters
Use backslash \ to insert special characters:
| Escape | Meaning |
|---|---|
\n |
Newline |
\t |
Tab |
\\ |
Backslash |
\" |
Double quote |
\' |
Single quote |
print("Hello\nWorld")
print("She said, \"Hi!\"")
Raw Strings
Use r"..." to ignore escape characters (common in file paths):
path = r"C:\Users\Alice"
print(path)
Tips for Working with Strings
-
Use f-strings for clean and efficient formatting.
-
Remember strings are immutable – you can’t change characters directly.
-
Use
.strip()to clean up input from users or files. -
Break long strings using
\or parentheses:
long_string = (
"This is a very long string "
"that spans multiple lines."
)
⚠️ Common Pitfalls
| Mistake | Explanation |
|---|---|
Using + too much |
Prefer join() for efficiency when combining many strings |
| Forgetting strings are immutable | You can't do s[0] = 'X' |
| Misusing escape characters | Use raw strings or escape properly |
| Mixing strings and numbers | Use str() or int() to convert types |
What's Next?
Once you're comfortable with strings, dive deeper into:
-
Regular expressions (with the
remodule) -
String encoding and decoding
-
Text processing and file I/O
Summary
| Concept | Example |
|---|---|
| Create a string | s = "Hello" |
| Access character | s[1] → 'e' |
| Slice string | s[0:4] → 'Hell' |
| Concatenate | "Hi" + "!" → 'Hi!' |
| Format | f"{name} is {age}" |
| Methods | .lower(), .replace(), .split() |
Tips and Tricks
What is pass in Python?
Python | Pass Statement
The pass statement is used as a placeholder for future code. It represents a null operation in Python. It is generally used for the purpose of filling up empty blocks of code which may execute during runtime but has yet to be written.
def myfunction():
pass
How can you generate random numbers?
Python | Generate random numbers
Python provides a module called random using which we can generate random numbers. e.g: print(random.random())
We have to import a random module and call the random() method as shown below:
import random
print(random.random())
The random() method generates float values lying between 0 and 1 randomly.
To generate customized random numbers between specified ranges, we can use the randrange() method
Syntax: randrange(beginning, end, step)
import random
print(random.randrange(5,100,2))
What is lambda in Python?
Python | Lambda function
A lambda function is a small anonymous function. This function can have any number of parameters but, can have just one statement.
Syntex:
lambda arguments : expression
a = lambda x,y : x+y
print(a(5, 6))
It also provides a nice way to write closures. With that power, you can do things like this.
def adder(x):
return lambda y: x + y
add5 = adder(5)
add5(1) #6
As you can see from the snippet of Python, the function adder takes in an argument x and returns an anonymous function, or lambda, that takes another argument y. That anonymous function allows you to create functions from functions. This is a simple example, but it should convey the power lambdas and closures have.
What is swapcase() function in the Python?
Python | swapcase() Function
It is a string's function that converts all uppercase characters into lowercase and vice versa. It automatically ignores all the non-alphabetic characters.
string = "IT IS IN LOWERCASE."
print(string.swapcase())
How to remove whitespaces from a string in Python?
Python | strip() Function | Remove whitespaces from a string
To remove the whitespaces and trailing spaces from the string, Python provides a strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns the original string.
string = " Python "
print(string.strip())
What is the usage of enumerate() function in Python?
Python | enumerate() Function
The enumerate() function is used to iterate through the sequence and retrieve the index position and its corresponding value at the same time.
lst = ["A","B","C"]
print (list(enumerate(lst)))
#[(0, 'A'), (1, 'B'), (2, 'C')]
Can you explain the filter(), map(), and reduce() functions?
Python | filter(), map(), and reduce() Functions
- filter() function accepts two arguments, a function and an iterable, where each element of the iterable is filtered through the function to test if the item is accepted or not.
>>> set(filter(lambda x:x>4, range(7))) # {5, 6}
-
map() function calls the specified function for each item of an iterable and returns a list of result
>>> set(map(lambda x:x**3, range(7))) # {0, 1, 64, 8, 216, 27, 125}
-
reduce() function reduces a sequence pair-wise, repeatedly until we arrive at a single value..
>>> reduce(lambda x,y:y-x, [1,2,3,4,5]) # 3Let’s understand this:
2-1=1
3-1=2
4-2=2
5-2=3Hence, 3.
What is a namedtuple?
Python | namedtuple
A namedtuple will let us access a tuple’s elements using a name/label. We use the function namedtuple() for this, and import it from collections.
>>> from collections import namedtuple
#format
>>> result=namedtuple('result','Physics Chemistry Maths')
#declaring the tuple
>>> Chris=result(Physics=86,Chemistry=92,Maths=80)
>>> Chris.Chemistry
# 92
Write a code to add the values of same keys in two different dictionaries and return a new dictionary.
We can use the Counter method from the collections module
from collections import Counter
dict1 = {'a': 5, 'b': 3, 'c': 2}
dict2 = {'a': 2, 'b': 4, 'c': 3}
new_dict = Counter(dict1) + Counter(dict2)
print(new_dict)
# Print: Counter({'a': 7, 'b': 7, 'c': 5})
Python In-place swapping of two numbers
Python | In-place swapping of two numbers
>>> a, b = 10, 20
>>> print(a, b)
10 20
>>> a, b = b, a
>>> print(a, b)
20 10
Reversing a String in Python
Python | Reversing a String
>>> x = 'PythonWorld'
>>> print(x[: : -1])
dlroWnohtyP
Python join all items of a list to convert into a single string
Python | Join all items of a list to convert into a single string
>>> x = ["Python", "Online", "Training"]
>>> print(" ".join(x))
Python Online Training
python return multiple values from functions
Python | Return multiple values from functions
>>> def A():
return 2, 3, 4
>>> a, b, c = A()
>>> print(a, b, c)
2 3 4
Python Print String N times
Python | Print String N times
>>> s = 'Python'
>>> n = 5
>>> print(s * n)
PythonPythonPythonPythonPython
Python check the memory usage of an object
Python | Check the memory usage of an object
>>> import sys
>>> x = 100
>>> print(sys.getsizeof(x))
28
