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What is F-Strings in python?

ICSM Computer 1639 16 Sep 2025

What is F-Strings in python, explain with example?

Ask by ICSM Computer

Updated 17 Sep 2025

1 Answers

Anubhav Sharma 16 Sep 2025

What are F-Strings?

F-strings (formatted string literals) were introduced in Python 3.6.
They let you embed expressions inside string literals, using {}.
They start with a prefix f or F.

Example:

name = "Anna"
age = 25
print(f"My name is {name} and I am {age} years old.")
# Output: My name is Anna and I am 25 years old.

Why Use F-Strings?

Cleaner and faster than .format() or % formatting.
You can write expressions directly inside {}.

Example:

x = 10
y = 20
print(f"{x} + {y} = {x + y}")
# Output: 10 + 20 = 30

Features of F-Strings

1. Expressions inside {}

print(f"Square of 5 is {5**2}")
# Output: Square of 5 is 25

2. Function calls inside {}

def greet(name):
    return f"Hello, {name}!"

print(f"{greet('Anna')}")
# Output: Hello, Anna!

3. Formatting numbers

pi = 3.14159265
print(f"Pi rounded to 2 decimals: {pi:.2f}")
# Output: Pi rounded to 2 decimals: 3.14

4. Date formatting

from datetime import datetime
today = datetime.now()
print(f"Today is {today:%d-%m-%Y}")
# Output: Today is 17-09-2025  (example)

5. Debugging (Python 3.8+)

You can append = inside {} to print both the expression and its value:

x = 5
print(f"{x=}")
# Output: x=5

Performance

F-strings are faster than .format() and % formatting because they are evaluated at runtime and don’t need extra function calls.

Example:

name = "Anna"
age = 25
# Old style
print("My name is %s and I am %d" % (name, age))
# str.format()
print("My name is {} and I am {}".format(name, age))
# F-string
print(f"My name is {name} and I am {age}")

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