Index above range
Input
clamp_index(10, 4)
Output
3
The valid indices for length 4 are 0..3. 10 is clamped to 3.
Full lesson preview
Clamp a list index to a valid range
Write a small utility that clamps an index to the valid range for a sequence length. Handle edge cases like zero or negative lengths.
Python practice8 minError Handling & Edge CasesBeginnerLast updated March 20, 2026
Problem statement
When accessing list elements by index you often need to ensure the index is within bounds. Implement a function clamp_index(index, length) that returns an integer index guaranteed to be valid for a sequence of the given length. Rules:
- If length is greater than 0, return the index clamped to the inclusive range [0, length-1].
- If length is 0 or negative, return 0 (there is no valid positive index, so 0 acts as a safe default).
- Treat the index as an integer (assume callers provide integers). Your implementation should be defensive against surprising length values.
Return the computed integer index.
Task
Implement clamp_index(index, length) that returns a safe index between 0 and length-1. Be defensive about invalid lengths.
Examples
Input format
Two integers: index and length (sequence length).
Output format
An integer: the clamped index.
Constraints
Do not raise for unexpected length values; handle length <= 0 by returning 0. Assume index is an integer.
Samples
Sample 1
Input
clamp_index(-2, 3)
Output
0
Negative indices are clamped to 0.