Bc (programming language): Difference between revisions

Revision as of 19:01, 16 February 2022

Revision as of 23:46, 17 February 2022

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==History==

bc first appeared in [[Version 6 Unix]] in 1975. andIt was written by [[Robert Morris (cryptographer)|Robert Morris]] and [[Lorinda Cherry]] of [[Bell Labs]]. bcas wasa precededfront byend to [[dc (computer program)|dc]], an earlier arbitrary-precision calculator written by the[[Robert sameMorris (cryptographer)|Robert authorsMorris]] and Cherry. dc could doperformed arbitrary-precision calculations,computations butspecified itsin [[reverse Polish notation]]. (RPN)bc syntax—muchprovided loveda byconventional many for evaluating algebraic formulas<!-programming-language who?interface just about ''everyone'' who possessed an expensive [[HP calculators]] ofto the erasame -->—provedcapability inconvenient to its users when expressing flow control, and therefore bc was written asvia a front-end to dc. bc was a very simple [[compiler]] (a single [[yacc]] source file withcomprising a few hundred lines of code), which converted thea new,[[C (programming language)|C]]-like, bc syntax into dc's [[postfix notation]] and [[Pipeline (Unix)|piped]] the results through dc.

In 1991, [[POSIX]] rigorously defined and standardized bc. Three implementations of this standard survive today: The first is the traditional Unix implementation, a front-end to dc, which survives in Unix and [[Plan 9 from Bell Labs|Plan 9]] systems. The second is the [[free software]] [[GNU]] bc, first released in 1991 by Philip A. Nelson. The GNU implementation has numerous extensions beyond the POSIX standard and is no longer a front-end to dc (it is a [[bytecode interpreter]]). The third is a re-implementation by OpenBSD in 2003.