BCPL

BCPL （正體）

BCPL（Basic Combined Programming Language），是一种电脑程式设计语言，1966年由剑桥大学的马丁·理察斯（Martin Richards）所发展出来的。

身为早期编程语言的BCPL，如今已不再广泛使用，但它的影响却是深远的，今日流行的C语言即是参考BCPL所设计。BCPL是第一支使用括号语言，括号特征在C语言中随处可见，例如

BCPL

LET FUNC foo(a) = VALOF
{ b := a + 1
  RESULTIS b }

C语言改良自BCPL

for (int i = 0; i < 10; i++)
{
    printf("%d", i);
    doTask(i);
}

BCPL又源自更早的CPL（Combined Programming Language）语言。Richards试着移除了CPL中最复杂的组成，第一支BCPL compiler在IBM 7094电脑中完成。

范例

下列是马丁查理斯的 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个皇后问题:

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
}

参考文献

• 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

Why are we here?
All text is available under the terms of the GNU Free Documentation License
This page is cache of Wikipedia. History