How to Check if a Key Exists in a Dictionary in Python

How to Check if a Key Exists in a Dictionary in Python ?

Answer

To check if a key exists in a dictionary in Python, you can use the `in` keyword. This allows you to check for the presence of a key in a dictionary.

✐ Examples

1 Checking if a Key Exists Using the `in` Keyword

We can check if a key exists in a dictionary in Python using the `in` keyword. This example demonstrates how to check for the presence of a key and print a message based on the result.

For example,

We start by declaring and initializing a dictionary named my_dict with integer keys and string values.
We use the `in` keyword to check if a key exists in the dictionary.
We print a message based on whether the key exists or not.

Python Program

my_dict = {
    1: 'One',
    2: 'Two',
    3: 'Three'
}

# Key to check
key_to_check = 2

# Check if the key exists using the in keyword
if key_to_check in my_dict:
    print(f'Key {key_to_check} exists in the dictionary.')
else:
    print(f'Key {key_to_check} does not exist in the dictionary.')

Output

Key 2 exists in the dictionary.

2 Checking if a Key Does Not Exist Using the `in` Keyword

We can check if a key does not exist in a dictionary in Python using the `in` keyword. This example demonstrates how to check for the absence of a key and print a message based on the result.

For example,

We start by declaring and initializing a dictionary named my_dict with integer keys and string values.
We use the `in` keyword to check if a key does not exist in the dictionary.
We print a message based on whether the key exists or not.

Python Program

my_dict = {
    1: 'One',
    2: 'Two',
    3: 'Three'
}

# Key to check
key_to_check = 4

# Check if the key does not exist using the in keyword
if key_to_check not in my_dict:
    print(f'Key {key_to_check} does not exist in the dictionary.')
else:
    print(f'Key {key_to_check} exists in the dictionary.')

Output

Key 4 does not exist in the dictionary.

Summary

In this tutorial, we learned How to Check if a Key Exists in a Dictionary in Python language with well detailed examples.

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How to Check if a Key Exists in a Dictionary in Python