BCPL

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BCPL
编程范型 过程式命令式结构化
发行时间 1966
設計者 馬丁·理察德
啟發語言 CPL
影響語言 B语言(间接影响C语言

BCPL(Basic Combined Programming Language),是一種電腦程式設計語言,源自更早的CPL語言,1966年由劍橋大學的馬丁·理察德(Martin Richards)所發展出來的。

Richards試著移除了CPL中最複雜的組成,第一支BCPL compiler在IBM 7094電腦中完成。

身為早期程式語言的BCPL,如今已不再廣泛使用,但它的影響卻是深遠的,今日流行的C語言即是參考BCPL所設計。BCPL是第一支使用括弧語言括弧特徵在C語言中隨處可見,例如

BCPL
LET FUNC foo(a) =  VALOF
{ b := a + 1
  RESULTIS b }
C語言改良自BCPL
for (int i =  0; i < 10; i++)
{
    printf("%d", i);
    doTask(i);
}

範例[编辑]

下列是馬丁查理斯的 BCPL distribution.

Printing factorials:

GET "libhdr"

LET start() = VALOF
{ FOR i = 1 TO 5 DO writef("fact(%n) = %i4*n", i, fact(i))
  RESULTIS 0
}

AND fact(n) = n=0 -> 1, n*fact(n-1)

N個皇后問題

GET "libhdr"
 
GLOBAL { count:200; all:201  }
 
LET try(ld, row, rd) BE TEST row=all

                        THEN count := count + 1

                        ELSE { LET poss = all & ~(ld | row | rd)
                               UNTIL poss=0 DO
                               { LET p = poss & -poss
                                 poss := poss - p
                                 try(ld+p << 1, row+p, rd+p >> 1)
                               }
                             }

LET start() = VALOF
{ all := 1
  
  FOR i = 1 TO 12 DO
  { count := 0
    try(0, 0, 0)
    writef("Number of solutions to %i2-queens is %i5*n", i, count)
    all := 2*all + 1
  }

  RESULTIS 0
}

參考文獻[编辑]

  • Martin Richards, The BCPL Reference Manual (Memorandum M-352, Project MAC, Cambridge, July, 1967)
  • Martin Richards, BCPL - a tool for compiler writing and systems programming (Proceedings of the Spring Joint Computer Conference, Vol 34, pp 557-566, 1969)
  • Martin Richards, Arthur Evans, Robert F. Mabee, The BCPL Reference Manual (MAC TR-141, Project MAC, Cambridge, 1974)
  • Martin Richards, C. Whitby-Strevens, BCPL, the language and its compiler (Cambridge University Press, 1980) ISBN 0-521-28681-6