Python String Interpolation: A Guide

In this article, we will explore Python string interpolation and how to use it in your code. We will start by defining what string interpolation is, and then we will move on to the different types of string interpolation in Python. We will also provide examples of how to use string interpolation in your code.

What is String Interpolation?

String interpolation is the process of inserting values into a string. In Python, there are several ways to achieve this, and we will explore them in detail.

Types of String Interpolation in Python

There are several ways to perform string interpolation in Python, and we will explore the most common ones:

1. Using the % Operator

The % operator is one of the oldest ways to perform string interpolation in Python. It is also known as the string formatting operator. This operator works by replacing placeholders in a string with values.

Here is an example:

name = "John"
age = 25
print("My name is %s and I am %d years old." % (name, age))

Output:

My name is John and I am 25 years old.

In the above example, %s is a placeholder for a string, and %d is a placeholder for an integer. The values for these placeholders are provided in a tuple at the end of the string.

2. Using the format() Method

The format() method is a newer way to perform string interpolation in Python. It is more flexible than the % operator and provides more options for formatting.

Here is an example:

name = "John"
age = 25
print("My name is {} and I am {} years old.".format(name, age))

Output:

My name is John and I am 25 years old.

In the above example, {} is a placeholder for a value. The values for these placeholders are provided in the format() method.

3. Using f-strings (Python 3.6+)

f-strings are the newest way to perform string interpolation in Python. They are similar to the format() method, but they are more concise and easier to read.

Here is an example:

name = "John"
age = 25
print(f"My name is {name} and I am {age} years old.")

Output:

My name is John and I am 25 years old.

In the above example, {} is a placeholder for a value, and the value is provided directly in the string.

4. Using Template Strings

Template strings are another way to perform string interpolation in Python. They are similar to f-strings, but they are less flexible.

Here is an example:

from string import Template

name = "John"
age = 25
template = Template("My name is $name and I am $age years old.")
print(template.substitute(name=name, age=age))

Output:

My name is John and I am 25 years old.

In the above example, $name and $age are placeholders for values. The values for these placeholders are provided using the substitute() method.

Conclusion

String interpolation is an essential feature in Python that allows you to insert values into a string. In this article, we explored the different types of string interpolation in Python, including the % operator, the format() method, f-strings, and template strings. We hope this article helps you understand string interpolation in Python and how to use it in your code.