Add line numbers

When line numbers come in handy

Compilers and interpreters report problems by line only ("error at line 42"): numbering the snippet you share on a forum, in a chat, or in a code review lets whoever is helping you reply by pointing to the exact line, with no counting by hand. Line numbering is also standard in legal documents and contracts, where clauses are referenced by line, and in interview transcripts, where quotes need to be cited with precision, think of a court deposition, where every line of the record is numbered for exactly this reason.

Which format to choose

The "1." format is the classic ordered-list style and the most readable in documents; "1)" is common in notes and meeting minutes. The "001" format with leading zeros keeps the columns perfectly aligned even past line 99 and is ideal for logs and lists that will be sorted alphabetically: without the zeros, line 10 would sort before line 2. The custom starting number is useful when you paste an excerpt from a larger file: if your block starts at line 120 of the source, the numbering can pick up right from there.

The last two formats, the bullet «•» and the dash «-», don't number anything: they put the same marker in front of every line, like Lines to bullet list. Empty lines can get the marker or stay empty (and then they don't count), and markers already at the start of the lines can be removed: list markers («- », «• ») always, numbers («3. », «4. ») when they go up one at a time, like the ones the tool writes. That way, running it again on its own result doesn't double the numbers, and a year at the start of a line («1969. ») stays where it is. Only one space goes with the marker: code indentation stays.