Concatenate String and Int in Python

Introduction

Python supports string concatenation using the + operator. In most other programming languages, if we concatenate a string with an integer (or any other primitive data types), the programming language automatically takes care of converting them to a string and then concatenates it seamlessly.

However, in Python, if you try to concatenate a string with an integer using the + operator, you will get a runtime error.

Example for Concatenate String and Int

Let’s look at an example for concatenating a string (str) and an integer (int) using the + operator.

string_concat_int.py
current_year_message = 'Year is '

current_year = 2018

print(current_year_message + current_year)
  

The desired output is the string: Year is 2018. However, when we run this code we get the following runtime error:

Traceback (most recent call last):
  File "/Users/sammy/Documents/github/journaldev/Python-3/basic_examples/strings/string_concat_int.py", line 5, in <module>
    print(current_year_message + current_year)
TypeError: can only concatenate str (not "int") to str
  

So how do you concatenate str and int in Python? There are various other ways to perform this operation.

Prerequisites for Concatenate String and Int

In order to complete this tutorial, you will need:

• Familiarity with installing Python 3 and coding in Python. Check out the How to Code in Python 3 series or use VS Code for Python.
• This tutorial was tested with Python 3.9.6.

Using the str() Function

We can pass an int to the str() function, and it will be converted to a str:

print(current_year_message + str(current_year))
  

The current_year integer is returned as a string: Year is 2018.

Using the % Interpolation Operator

We can pass values to a conversion specification with printf-style String Formatting:

print("%s%s" % (current_year_message, current_year))
  

The current_year integer is interpolated to a string: Year is 2018.

Using the str.format() Function

We can also use the str.format() function for concatenation of string and integer:

print("{}{}".format(current_year_message, current_year))
  

The current_year integer is type coerced to a string: Year is 2018.

Using f-strings to Concatenate String and Int

If you are using Python 3.6 or higher versions, you can use f-strings, too:

print(f'{current_year_message}{current_year}')
  

The current_year integer is interpolated to a string: Year is 2018.

Conclusion

You can check out the complete Python script and explore many additional Python examples, tutorials, and detailed guides directly from our GitHub repository for free.