Add Line Numbers

An Add Line Numbers Tool is a text-formatting utility used to prefix each line of a document with a sequential numerical index. This tool is essential for developers, legal professionals, and copyeditors referencing specific lines of code, reviewing legal contracts, or preparing manuscripts for peer review.

The processing engine handles line indexing through a three-stage formatting pipeline:

1. Line Parsing: The tool scans the input string and splits it based on line break characters (e.g., \n or \r\n).
2. Sequential Indexing: The engine generates a counter starting from your "Start Number" (typically 1) and increments it for every segment found.
3. Stylistic Prefixing: The tool applies custom formatting to the numbers:
   • Padding: Adding leading zeros (e.g., 001, 002) for visual alignment.
   • Separators: Adding symbols like ., :, or ) after the number.
   • Right/Left Alignment: Ensuring the numbers don't shift the text unevenly.
4. Reactive Real-time Rendering: The "Numbered" text and total line count update instantly as you input or adjust the text.

The History of Line Numbers: From Parchment to Python

The use of line numbers has always been about "Precise Referencing."

• Legal Manuscripts (Ancient): Scribal traditions in law used line numbering to ensure that different parties were literally "on the same page" during disputes. This exists today in Line-Numbered Legal Citations.
• The "Basic" Language (1964): Early programming languages like BASIC (Beginner's All-purpose Symbolic Instruction Code) required line numbers (e.g., 10 PRINT "HELLO", 20 GOTO 10) for the computer to understand the execution order.
• The Modern Code Review: Today, line numbers are the universal language of GitHub and Version Control. Without them, debugging software would be nearly impossible.

Technical Comparison: Line Referencing Standards

Understanding indexing is vital for Data Engineering and Legal Review.

standard	Goal	usage	Workflow Impact
Padded (001)	Visual Alignment	Printed Documents	Readability
Plain (1.)	General Listing	Lists / Drafts	Speed
Hex (0x01)	Memory Mapping	Binary Analysis	Precision
Roman (i.)	Outlining	Preface / TOC	Hierarchy
Legal (1:1)	Chapter & Line	Legal Filings	Authority

By using this tool, you ensure your Source Code and Official Documents are perfectly indexed for collaborative review.

Security and Privacy Considerations

Your text numbering is performed in a secure, local environment:

• Local Logical Execution: All numbering is performed locally in your browser. Your sensitive files—which could include source code or court documents—never touch our servers.
• Zero Log Policy: We do not store or track your inputs. Your Proprietary Code and Private Legal Drafts remain entirely confidential.
• W3C Security Compliance: The tool operates within the standard browser sandbox, ensuring no interaction with your local file system or Private Metadata.
• Privacy First: To maintain absolute Data Privacy, the tool functions as an anonymous utility.

How It's Tested

We provide a high-fidelity engine that is verified against Standard POSIX Text Formatting patterns.

1. The "Start Number" Pass:
   • Action: Set start to 10 on a 1-line text.
   • Expected: Result must show 10. [text].
2. The "Empty Line" Check:
   • Action: Number a block with blank lines.
   • Expected: The tool must correctly choose whether to skip or number the blank lines based on user settings.
3. The "Padding" Test:
   • Action: Use 3-digit padding (001) on 10 lines.
   • Expected: The Formatting engine must correctly prefix with 001, 002, up to 010.
4. The "Large Document" Defense:
   • Action: Process a 5,000-line CSV.
   • Expected: The tool must generate the index without lag or memory issues in the browser.