200-901 Software Development and Design Practice Question
Given the following Python code snippet:
with open('config.json', 'r') as f:data = json.load(f)
print(data['interfaces'][0]['name'])
What is the expected output if config.json contains {"interfaces": [{"name": "GigabitEthernet0/1"}]}?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
GigabitEthernet0/1
json.load() reads the file and returns a dict; then accessing the nested structure yields 'GigabitEthernet0/1'.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
GigabitEthernet0/1
Why this is correct
The code parses the JSON file into a Python dictionary, then indexes the `interfaces` list to retrieve its first element and reads that dictionary's `name` key. Given the supplied file content, this resolves to the string `GigabitEthernet0/1`, which `print` outputs without quotes.
- ✗
None
Why it's wrong here
The expression indexes the interfaces list at position 0 and then retrieves the name key, which holds the string GigabitEthernet0/1; nothing in the snippet yields None. It is tempting because a missing key would raise KeyError rather than return None, and None appears only when a lookup explicitly returns it.
- ✗
interfaces
Why it's wrong here
The string 'interfaces' is the dictionary key used for lookup, not the value printed; the code drills into the first list element and reads its name field. It is tempting because the key name appears literally in the source, yet the print statement targets the nested name value, not the key itself.
- ✗
Error: list indices must be integers
Why it's wrong here
The list is indexed with the integer 0, so no type error occurs; the subscript is valid and returns the first dictionary. It is tempting because indexing a list with a string does raise that exact error, but here the integer literal 0 is used, making the operation legal and the output the interface name.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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