Indexed Arrays

Indexed arrays commonly start at zero. Read an element with square brackets and append a new value with []. Check bounds before accessing an index that may not exist; for a list, count gives its number of items but the last index is count minus one. The example appends a language and reports the resulting number of items. Further guidance Choose list indexes for ordered items and descriptive keys for named fields. Check whether an expected key exists before reading it, and preserve keys when their association matters during sorting or filtering. Use a small fixture to test empty, single-item, and nested data. Practice task: Create a fresh example for Indexed Arrays. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.