Difference between %s and %d in Python string

In this article, we will see the difference between %s and %d in Python. Here, we start with the proper explanation of one at a time, then both, and at last compare these.

What does %s do in Python?

The % symbol is used in Python with a large variety of data types and configurations. It is used as an argument specifier and string formatter. %s specifically is used to perform the concatenation of strings together. It allows us to format a value inside a string. It is used to incorporate another string within a string. It automatically provides type conversion from value to string.

How to Use %s in Python

The %s operator is put where the string is to be specified. The number of values you want to append to a string should be equivalent to the number specified in parentheses after the % operator at the end of the string value. The following code illustrates the usage of the %s symbol :

Python3

# declaring a string variable
name = "Geek"

# append a string within a string
print("Hey, %s!" % name)

Output

Hey, Geek!

What does %d do in Python? 

The %d operator is used as a placeholder to specify integer values, decimals, or numbers. It allows us to print numbers within strings or other values. The %d operator is put where the integer is to be specified. Floating-point numbers are converted automatically to decimal values. 

Python3

# declaring numeric variables
num = 2021

# concatenating numeric value within string
print("%d is here!!" % num)

Output

2021 is here!!

How to Use %d in Python

The decimal and rational numbers are rounded off to the absolute integral part and the numbers after the decimal are scraped off, that is only the integers are extracted. The following code illustrates the usage of %d with decimal and fractional numbers:

Python3

# declaring rational number
frac_num = 8/3

# concatenating numeric value within string
print("Rational number formatting using %d")
print("%d is equal to 8/3 using this operator." % frac_num)

# declaring decimal number
dec_num = 10.9785

# concatenating numeric value within string
print("Decimal number formatting using %d")
print("%d is equal to 10.9785 using this operator." % dec_num)

Output

Rational number formatting using %d
2 is equal to 8/3 using this operator.
Decimal number formatting using %d
10 is equal to 10.9785 using this operator.

Difference Between %s and %d?

We can use a combination of operators also within a single program. Before that first, clear some concepts by comparing as given below :

%s operator	%d operator
It is used as a placeholder for string values.	It is used as a placeholder for numeric values.
Uses string conversion via str() before formatting.	Uses decimal conversion via int() before formatting.
%s can accept numeric values also and it automatically does the type conversion.	In case a string is specified for the %d operator a type error is returned.

Common Errors Using %s and %d

Example 1:

The %s automatically converts a numeric value to a string without throwing an error. 

Python3

name = "Sita"
age = 22
print("Using %s ")
print ("%s's age is %s."%(name,age))

Output

Using %s 
Sita's age is 22.

Example 2:

 The %d, however, can only be used for numeric values. Otherwise, an error is returned. 

Python3

name = "Sita"
age = 22
print("Using %d")
print ("%d's age is %d."%(name,age))

Error

Using %d
Traceback (most recent call last):
 File "<string>", line 4, in <module>
TypeError: %d format: a number is required, not str