Editing PL/C (section)

== Textbooks ==
The textbook ''An Introduction to Programming: A Structured Approach Using PL/I and PL/C'' was written by Conway and Gries using PL/C as the programming language and was published in 1973.<ref name="conway-gries">{{Cite book
  |title       = An Introduction to Programming: A Structured Approach Using PL/I and PL/C
  |last1       = Conway
  |first1      = Richard W.
  |author-link1= Richard W. Conway
  |last2       = Gries
  |first2      = David
  |author-link2= David Gries
  |publisher   = Winthrop Publishers
  |location    = Cambridge, Massachusetts
  |edition     = 
  |year        = 1973
  |doi         = 
  |series      =
  |url         = https://books.google.com/books?id=C74mAAAAMAAJ
  |pages       = (iii), 3, 9, 192–206, 232−236, and ''passim''
|isbn = 9780876264065
 }} (Note the first edition uses "PL/1" on the cover but "PL/I" on the title page and in the text itself.)</ref>  It presented [[top-down design]],<ref name="cdsun-111578">{{cite news | url=https://cdsun.library.cornell.edu/cgi-bin/imageserver.pl?oid=CDS19781115&getpdf=true | title=Computer Dept. Wins Prominence Throughout U.S. | author-first=Michael | author-last=Palazzo | newspaper=The Cornell Daily Sun | date=November 15, 1978 | pages=1, 10, 11 }}</ref> and stressed the discipline of structured programming throughout, becoming one of the most prominent textbooks to do so.<ref name="ij-2nd-ed"/>  One section of the book was devoted to considerations of [[program correctness]], such as the [[Invariant Relation Theorem]];<ref name="conway-gries"/> it is said to have been the first programming textbook to incorporate such material.<ref name="cornell_cs_timeline"/>  The book had a potential market at any university using PL/C, and Conway later said that the book had sold very well.<ref name=CUPL.Conway/>  

A second edition was published in 1975.<ref name="ij-2nd-ed">{{cite news | url=https://www.newspapers.com/clip/110544982/the-ithaca-journal/ | title=Computer Text Is Updated | newspaper=The Ithaca Journal | date=June 30, 1975 | page=6 | via=Newspapers.com}}</ref>  Besides reorganizing some material on the development and testing of computer programs,<ref name="ij-2nd-ed"/> it incorporated changes due to Release 7 of the PL/C compiler.<ref>See Second Edition, "Preface", [https://archive.org/details/introductiontopr0000conw/page/n17/mode/2up p. xiv].</ref>  A third edition was published in 1979 and, besides pitching the textbook material at a somewhat higher level to reflect that many college students had previous programming exposure in high school, incorporated additions to reflect the PL/CT and PL/CS variants of PL/C.<ref>See Third Edition, "Preface", [https://archive.org/details/introductiontopr0000conw_m6u1/page/n19/mode/2up?view=theater pp. xv–xvi].</ref>

''An Introduction to Programming: A Structured Approach'' was used as the basis for several offshoot textbooks, sometimes with additional co-authors, that were either aimed at a more beginning level or that covered other languages or dialects.<ref>{{cite web | url=https://www.cs.cornell.edu/gries/texts.html | title=Texts by David Gries | publisher=Department of Computer Science, Cornell University | access-date=September 23, 2022 }}</ref>