f-strings in Python

PEP 498 introduced a new string formatting mechanism known as Literal String Interpolation or more commonly as F-strings (because of the leading f character preceding the string literal). The idea behind f-strings is to make string interpolation simpler. 
To create an f-string, prefix the string with the letter “ f ”. The string itself can be formatted in much the same way that you would with str.format(). F-strings provide a concise and convenient way to embed python expressions inside string literals for formatting. 

Code #1 :

Python3

# Python3 program introducing f-string
val = 'Geeks'
print(f"{val}for{val} is a portal for {val}.")


name = 'Tushar'
age = 23
print(f"Hello, My name is {name} and I'm {age} years old.")

Output :

GeeksforGeeks is a portal for Geeks.
Hello, My name is Tushar and I'm 23 years old.

Code #2 :

Python3

# Prints today's date with help
# of datetime library
import datetime

today = datetime.datetime.today()
print(f"{today:%B %d, %Y}")

Output :

April 04, 2018

Note : F-strings are faster than the two most commonly used string formatting mechanisms, which are % formatting and str.format(). 

Let’s see few error examples, which might occur while using f-string :
Code #3 : Demonstrating Syntax error. 

Python3

answer = 456
f"Your answer is "{answer}""

Code #4 : Backslash Cannot be used in format string directly.

Python3

f"newline: {ord('\n')}"

Output :

Traceback (most recent call last):
  Python Shell, prompt 29, line 1
Syntax Error: f-string expression part cannot include a backslash: , line 1, pos 0

But the documentation points out that we can put the backslash into a variable as a workaround though :

Python3

newline = ord('\n')

print(f"newline: {newline}")

Output :

newline: 10

Reference : PEP 498, Literal String Interpolation