Missing dict key
Input
get_with_default({'a': 1}, 'b', 0)
Output
0
Key 'b' is not in the dict, so default 0 is returned.
Full lesson preview
Return a default when a key is missing
Create a helper that extracts values from mappings or sequences and returns a fallback when the key/index is missing or the container is invalid.
Python practice9 minError Handling & Edge CasesBeginnerLast updated March 20, 2026
Problem statement
Accessing values can raise exceptions if the key or index is missing, or if the container is None or not subscriptable. Implement get_with_default(container, key, default) that:
- Returns container[key] when the access succeeds.
- If accessing container[key] raises KeyError, IndexError, or TypeError, return default instead.
- Be tolerant of common container types such as dicts and lists.
This function helps call sites remain robust when inputs are unpredictable.
Task
Implement get_with_default(container, key, default) that safely returns container[key] when available, otherwise returns default without raising errors.
Examples
Input format
Three values: container (e.g., dict or list), key (any hashable or integer index), default (any).
Output format
The value from container[key] or the default if not accessible.
Constraints
Do not raise when the container is None or the key/index is missing; return the default instead.
Samples
Sample 1
Input
get_with_default([10, 20], 1, 0)
Output
20
Index 1 exists in the list and returns 20.