Ruby Error
IndexError
IndexError is raised when trying to access an array element at an index that doesn't exist, typically when using fetch() or certain array methods.
Common causes
- Using Array#fetch with out-of-bounds index
- Accessing negative index beyond array size
- Using at() with invalid index on some objects
- Off-by-one errors in loops
How to fix it
- Check array length before accessing: array.length > index
- Provide default value: array.fetch(index, default)
- Use bracket notation: array[index] returns nil for missing
- Use safe methods like first, last, take, drop
- Validate index bounds before access
Example
IndexError example
# Error example
array = [1, 2, 3]
array.fetch(10) # => IndexError: index 10 outside of array bounds
# Fix with default value
array.fetch(10, nil) # => nil
# Fix with bracket notation
array[10] # => nil (no error)
# Check bounds first
index = 10
array[index] if index < array.lengthTrack IndexError with Checkend
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Related errors
KeyError
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ArgumentErrorArgumentError is raised when a method receives an argument it cannot handle. This includes wrong num...
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