The Curious History of Regex Anchors: Why `$` and `^`?
2025-01-21
This post delves into the historical origins of using `$` and `^` as line anchors in regular expressions. Tracing back to the QED text editor, `$` initially represented the end of the buffer, later adapted by Ken Thompson to signify the end of a line in regexes. The choice of `^` likely stemmed from the limited character set of the Teletype Model 35 typewriter, with `^` already present in ASCII-67. This wasn't a brilliant design choice but rather a consequence of hardware and character set limitations of that era, becoming a convention in regexes.
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