How to Check if a Key Exists in a Python Dictionary

Dictionaries in Python are very useful because they allow you to add, read, and remove key-value pairs.
When working with them, you will oftentimes need to know if a dictionary contains a key or not.
In this post, we'll learn how to check if a key exists in a dictionary in Python.
How to check if a key exists in a dictionary in Python
To start, let's create a dictionary:
dictionary = {
"name": "John",
"age": 30,
"city": "New York"
}
print(dictionary)
The output will be:
{'name': 'John', 'age': 30, 'city': 'New York'}
Now, let's say we want to check if the key "name" exists in the dictionary.
The best way to do this is to simply use the in
keyword.
This keyword will return True
if the key exists in the dictionary, and False
if it doesn't.
dictionary = {
"name": "John",
"age": 30,
"city": "New York"
}
key = "name"
if key in dictionary:
print("Key exists in dictionary")
else:
print("Key does not exist in dictionary")
Key exists in dictionary
Alternatively, you can also set the output of the in
keyword to a variable:
dictionary = {
"name": "John",
"age": 30,
"city": "New York"
}
key = "name"
key_exists = key in dictionary
print(key_exists)
True
Conclusion
In this post, we learned how to check if a key exists in a dictionary in Python.
Simply use the in
keyword on a dictionary and pass it the key you want to check.
Thanks for reading!
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