# Parallel Array Alignment Pattern

> Maintain index synchronization between parallel arrays when adding new entries to preserve label-path mappings

- Skill: `vamseeachanta/parallel-array-alignment-pattern` (Agent Skill)
- Install (CLI): `npx skillmds@latest add vamseeachanta/parallel-array-alignment-pattern`
- Raw SKILL.md: https://api.skillmd.com/api/skills/vamseeachanta/parallel-array-alignment-pattern/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: vamseeachanta (https://skillmd.com/u/vamseeachanta)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/vamseeachanta/parallel-array-alignment-pattern

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# Parallel Array Alignment Pattern

When modifying bash scripts that use parallel arrays (e.g., `SOURCE_LABELS` and `SOURCE_PATHS`), ensure new entries are appended to both arrays at matching indices. The loop that consumes these arrays typically iterates by index: `for i in "${!SOURCE_LABELS[@]}"; do ... "${SOURCE_LABELS[$i]}" ... "${SOURCE_PATHS[$i]}"`.

Before adding an entry, verify the current array length is identical across all parallel arrays. Add your new element to each array at the same position to prevent off-by-one misalignment that breaks the label-path relationship.