In this tutorial, I will explain how to check if a word is in a string in Python. As a Python developer based in the USA, I faced this challenge while developing a text-based application that needed to filter user input based on specific keywords. Let’s get into the various methods you can use to check for the presence of a word in a string, complete with practical examples.
Check if a Word is in a String in Python
Python provides various methods to check if a word is in a string. Let us see some important methods.
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1. Use the in Operator
The simplest and most Pythonic way to check if a word exists in a string is by using the in operator. This operator checks for membership and returns True if the substring is found, and False otherwise.
Example
text = "The quick brown fox jumps over the lazy dog."
word = "fox"
if word in text:
print("The word is present in the string.")
else:
print("The word is not present in the string.")Output:
The word is present in the string.I have executed the above code and added the screenshot below.
This method is not only simple but also very readable, making it a preferred choice among Python developers.
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2. Use the find() Method
Another way to check for a word in a string is by using the find() method. This method returns the lowest index of the substring if found in the string; otherwise, it returns -1.
Example
text = "The United States of America is a great country."
word = "America"
if text.find(word) != -1:
print("The word is present in the string.")
else:
print("The word is not present in the string.")Output:
The word is present in the string.I have executed the above code and added the screenshot below.
The find() method is useful when you also need to know the position of the substring within the string.
Read How to Check if a String Starts with a Specific Substring in Python?
3. Use the index() Method
Similar to find(), the index() method can also be used to locate a substring within a string. However, unlike find(), if the substring is not found, index() raises a ValueError.
Example
text = "California is known for its beautiful beaches."
word = "California"
try:
position = text.index(word)
print(f"The word is present in the string at index {position}.")
except ValueError:
print("The word is not present in the string.")Output:
The word is present in the string at index 0.I have executed the above code and added the screenshot below.
This method is beneficial if you want to ensure that the substring exists and handle the case where it does not.
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4. Use Regular Expressions
For more complex searches, regular expressions (regex) can be very powerful. The re module in Python allows you to perform advanced string searching and manipulation.
Example
import re
text = "The capital of the USA is Washington, D.C."
word = "Washington"
if re.search(word, text):
print("The word is present in the string.")
else:
print("The word is not present in the string.")Using regex is particularly useful when you need to match patterns rather than exact strings. This flexibility makes it a valuable tool for text-processing tasks.
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Case Sensitivity
It’s important to note that string searches in Python are case-sensitive. If you need to perform a case-insensitive search, you can convert both the string and the word to the same case using the lower() or upper() methods.
Example
text = "The President of the USA is Joe Biden."
word = "joe"
if word.lower() in text.lower():
print("The word is present in the string.")
else:
print("The word is not present in the string.")In this example, the search will correctly identify “joe” as present in the string, regardless of the case.
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Conclusion
In this tutorial, I have explained how to check if a word is in a string in Python. I discussed various methods like using in operator, find() method, index() method, regular expression and case sensitivity.
You may also like to read:
- How to Check if a String is Base64 Encoded in Python?
- How to Check if a String Begins with a Number in Python?
- How to Check if a String Contains All Unique Characters in Python?
I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.
