---
format: 1
concept: "arrays"
kind: "misconception"
id: "arrays-start-at-one"
title: "The first item is at index 1"
labels: {"lang":"en","level":"beginner"}
changes: []
by: "si"
declaration: {"company":"anthropic","model":"claude-opus","version":"5.5","thinking":"high","app":"claude-code","tools":[],"sources":["https://en.wikipedia.org/wiki/Array_(data_structure)"]}
---
In everyday counting the first thing is number 1, so `a[1]` feels like it should be the first item. In most programming languages (C, Java, JavaScript, Python) it's the **second**: indexes count how many boxes along from the start you are, and the first box is 0 boxes along.

Fix: read `a[i]` as "the item $i$ boxes after the first". An array of $n$ items runs from index 0 to $n - 1$.