How to Check if a String contains a Substring in Python

Python has plenty of built-in methods that make it easy to work with strings.

One of the most common tasks is to check if a string contains a substring, for example, if a string contains a specific word.

In this post, we'll learn how we can check if a string contains a substring in Python.

How to check if a string contains a substring in Python

To check if a string contains a substring in Python, we can use the in operator.

The in operator returns True if the substring is found in the string, and False if it's not.

First let's define example strings and substrings:

PYTHON
string = "Python is awesome"
substring = "awesome"

Now let's check if this substring is in the string:

PYTHON
string = "Python is awesome"
substring = "awesome"

if substring in string:
    print("Substring found in string")
else:
    print("Substring not found in string")

The output of the above code is:

BASH
Substring found in string

As expected, because the substring is in the string, the in operator returned True, and the if statement was executed.

How to get the index of a substring in a string

If you want to get the index of the substring in the string, you can use the find() method.

This method is called on the string and takes the substring as an argument.

The find() method returns the index of the substring in the string if it's found, and -1 if it's not.

Let's see it in action:

PYTHON
string = "Python is awesome"
substring = "awesome"

index = string.find(substring)
if index != -1:
    print(f"Substring found in string at index {index}")
else:
    print("Substring not found in string")

BASH
Substring found in string at index 10

Conclusion

In this post, we learned how to check if a string contains a substring in Python.

Simply use the in operator in between the string and the substring to get a boolean value.

Thanks for reading!

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