Python += Operator: A Guide

The Python += operator lets you add two values together and assign the resultant value to a variable. This operator is often referred to as the addition assignment operator. It is shorter than adding two numbers together and then assigning the resulting value using both a + and an = sign separately.

There may be a case where you want to add two values and assign the resulting value to a variable. That’s where Python’s addition assignment operator can come in handy.

This tutorial will discuss using the += operator to add two values and assign the final value to a variable. We’ll walk through two examples to illustrate this operator in action.

Python Operators

In Python, an operator is a symbol that represents a predefined operation. For instance, the plus sign (+) performs an addition operation, and the asterisk (*) performs a multiplication operation.

Suppose we want to keep a running total of two numbers in Python. We could do so using this code:

a = 10
a = a + 7.5
print(a)

Our code returns: 17.5. We assigned the value 10 to the variable a, and we assigned the value 7.5 to the variable b. Then, we added the two numbers using a + b. We printed out the result to the console.

The Python += Operator

The Python += operator adds two values together and assigns the final value to a variable. This operator is called the addition assignment operator. This operator is often used to add values to a counter variable that tracks how many times something has happened.

When you use the addition assignment operator, two numbers will be added. The resultant value will be assigned to a variable.

The syntax for this arithmetic operator is:

variable_name += value

The value of the variable you specify must be either a Python string or a number. A number can be an integer or a floating-point value.

Say you specify a string value. The value that comes after the equals sign will be added to the end of the value stored in the variable you specify. If you specify a numeric value, the two numbers will be added.

Let’s look at two examples of using to use the += operator.

+= Operator Python: Numerical Example

Suppose we want to keep a running total of a few numbers. We could do so using the += assignment operator, like this:

a = 10
a += 7.5
print(a)

Our code returns: 17.5. In our code, you can see that we have used the += operator. This operator is more “Pythonic” than the alternative. The alternative is using a plus sign to add two values and the equals sign to assign the value to a variable.

First, we declare a Python variable called a. This variable stores the value 10. Then, we use a += 7.5 to add 7.5 to the a variable. Finally, we print out the value of a to the console, which returns 17.5.

Using the addition assignment operator in this example is like writing out a = a + 7.5. The result is the same, but the addition assignment operator is easier to read.

+= Operator Python: String Example

We have a variable that stores a user’s first name. At the moment, this variable is equal to “John”. We also have a variable that stores John’s surname. The value of this variable is “Swanson”. You can see this variable below:

forename = "John"
surname = " Swanson"

We want to add these two names together. Notice that the user’s surname begins with a space. This is important because the += operator does not add a space to a value. We can merge our two names together using the following code:

forename += surname

Our code returns:

John Swanson

We have successfully merged the contents of our two variables.

Other Python Assignment Operators

The Python programming language offers a range of other assignment operators. You can also get membership operators, comparison operators, and identify operators in Python.

Assignment operators let you perform a mathematical function, then assign the resultant value to a variable. Here are a few of the main assignment operators offered by Python:

To learn more about how mathematical operators work in Python, read our beginner’s guide to Python math operators.

Conclusion

The Python += operator performs an addition operator and then assigns the result of the operation to a variable. The += operator is an example of a Python assignment operator. This operator is called the addition assignment operator.

This tutorial discussed, with reference to an example, the basics of Python operators and how to use the += assignment operator. Now you’re equipped with the knowledge you need to use the =+ operator like a professional Python developer!

Are you interested in learning more about the Python programming language? Check out our complete How to Learn Python guide with top learning resources and online courses.