Python dictionary value retrieval with key check

Last update on April 01 2025 13:19:02 (UTC/GMT +8 hours)

6. Dictionary Key Retrieval with Default

Write a Python program that defines a dictionary and retrieves a value using a key. If the key is not found, return None.

Sample Solution:

Code:

def retrieve_value(dictionary, key):
    if key in dictionary:
        return dictionary[key]
    else:
        return None

def main():
    try:
        person_data = {"name": "Bonifaas Shyam", "age": 25, "city": "Paris"}
        #person_data = {"name": "Bonifaas Shyam", "city": "Paris"}
        search_key = "age"
        
        result = retrieve_value(person_data, search_key)
        
        if result is None:
            print(f"Key '{search_key}' not found.")
        else:
            print(f"The value for key '{search_key}' is:", result)
    except Exception as e:
        print("An error occurred:", e)

if __name__ == "__main__":
    main()

Output:

The value for key 'age' is: 25

Key 'age' not found.

In the exercise above, the "retrieve_value()" function checks if the provided key exists in the dictionary. If it exists, it returns the corresponding value; otherwise, it returns None. The "main()" function demonstrates the function's usage by providing a sample dictionary and a search key. As soon as the key is found, or if it is not found, the value is printed.

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program that defines a dictionary and retrieves a value for a specified key, returning None if the key does not exist.
• Write a Python function to safely access a dictionary value by key and return None when the key is missing, without raising an exception.
• Write a Python script to iterate over a list of keys, retrieving corresponding dictionary values and returning None for any missing keys.
• Write a Python program to use the dictionary.get() method to fetch values and default to None if the key is not found.

Python Code Editor :

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