| Title | Why Do Regexes Use `$` and `^` as Line Anchors? | |
| Date | Wednesday March 27 2024, @08:12PM | |
| Author | janrinok | |
| Topic | ||
| from the I-didn't-know-that-... dept. | ||
https://buttondown.email/hillelwayne/archive/why-do-regexes-use-and-as-line-anchors/
Last week I fell into a bit of a rabbit hole: why do regular expressions use $ and ^ as line anchors?1
This talk brings up that they first appeared in Ken Thompson's port of the QED text editor. In his manual he writes: b) "^" is a regular expression which matches character at the beginning of a line.
c) "$" is a regular expression which matches character before the character (usually at the end of a line)
QED was the precursor to ed, which was instrumental in popularizing regexes, so a lot of its design choices stuck.
Okay, but then why did Ken Thompson choose those characters?
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printed from SoylentNews, Why Do Regexes Use `$` and `^` as Line Anchors? on 2024-10-05 19:42:14