[Solved] What happens if a JSON file contains duplicate keys when deserializing into a C# object? - Ans: The last key's value overwrites previous ones during deserialization | C Sharp (C#)

C Sharp (C#) - File IO

What happens if a JSON file contains duplicate keys when deserializing into a C# object?

ADeserialization throws an exception for duplicate keys

BThe last key's value overwrites previous ones during deserialization

CThe first key's value is kept and duplicates are ignored

DDeserialization merges values into a list automatically

Step-by-Step Solution

Solution:

Step 1: Understand JSON duplicate key behavior
During deserialization, if duplicate keys exist, the last occurrence overwrites earlier values.
Step 2: Check other options
No exception is thrown by default. The first value is not kept. Automatic merging into lists does not happen.
Final Answer:
The last key's value overwrites previous ones during deserialization -> Option B
Quick Check:
Duplicate JSON keys = last value wins [OK]

Quick Trick: Duplicate keys overwrite earlier values during deserialization [OK]

Common Mistakes:

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What happens if a JSON file contains duplicate keys when deserializing into a C# object?