Quick Answer

Handle list boundary issues safely.

Understanding the Issue

IndexError occurs when accessing list elements beyond their bounds. Common in loops or when assuming fixed list lengths. Python uses zero-based indexing (first element is index 0). Negative indices count from the end (-1 is last element).

The Problem

This code demonstrates the issue:

Python Error 
colors = ["red", "green"]
print(colors[5])  # Fails
print(colors[-3]) # Fails

The Solution

Here's the corrected code:

Python Fixed 
# Solution 1: Boundary checks
if len(colors) > 5:
    print(colors[5])

# Solution 2: Safe access
try:
    item = colors[5]
except IndexError:
    item = default_value

# Solution 3: Use get() for dict-like behavior
item = colors[5] if len(colors) > 5 else None

Key Takeaways

Always validate indices before access.