Python :F-Strings

In Python, to format output statements you can do in several ways as below.

1. Regular print() using parameter data types

2. Using .format()

3. Using F-string

I will write small examples using all 3 types.

1. Regular print() using parameter data types

In the below example I will define values and print same for 3 most used data types which are int, string, float

>>> a = 10
>>> b = "Hello"
>>> c = 98.9
>>> print("a value is %d b value is %s c value is %f" %(a, b, c))
a value is 10 b value is Hello c value is 98.900000

If you observe the float this is not what I have defined actually, but we are not without options either, we can restrict how many decimals we want. Check below code

>>> print("a value is %d b value is %s c value is %.2f" %(a, b, c))
a value is 10 b value is Hello c value is 98.90
>>> print("a value is %d b value is %s c value is %.3f" %(a, b, c))
a value is 10 b value is Hello c value is 98.900
>>>

Next let's do same with .format()

2. Using .format()

Using format we can also evaluate expressions while printing, below code snippets cover both normal printing and expressions which are evaluated

>>> a = 10
>>> b = "Hello"
>>> c = 98.9
>>> print("a value is {0}, b value is {1}, c value is {2}".format(a,b,c))
a value is 10, b value is Hello, c value is 98.9
>>> print("a value is {a}, b value is {b}, c value is {c}".format(a=a,b=b,c=c))
a value is 10, b value is Hello, c value is 98.9
>>> print("a value is {a}, b value is {b}, c value is {c}".format(a=a,b=b,c=c if c > 100 else 0))
a value is 10, b value is Hello, c value is 0

I am not adding any explanation here because the code itself self explanatory.

Now let's see F-Strings

>>> f'{a} {b} {c}'
'10 Hello 98.9'
>>> f'{a} {b} {c if c > 100 else 0 } '
'10 Hello 0 '
>>> print(f'{a} {b} {c if c > 100 else 0 } ')
10 Hello 0

Hope it helps.

Thank you.