279:(however, it has been shown that Befunge-93 is Turing Complete with unbounded stack word size). The later Funge-98 specification provides Turing completeness by removing the size restrictions on the program; rather than wrapping around at a fixed limit, the movement of a Funge-98 instruction pointer follows a model dubbed "Lahey-space" after its originator, Chris Lahey. In this model, the grid behaves like a torus of finite size with respect to wrapping, while still allowing itself to be extended indefinitely.
314:: each instruction is compiled to a snippet of C code, and control flows through the snippets just as it does in a Befunge interpreter (that is, conditionally on the value of some 'direction' register). This does not result in a significant advantage over a good interpreter. Note that the bef2c compiler is not correct since it does not handle either 'p' or string mode, but it would not be impossible to make it do so (although the C language might not be well-suited for this).
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As stated, the design goal for
Befunge was to create a language which was difficult to compile. This was attempted with the implementation of self-modifying code (the 'p' instruction can write new instructions into the playfield) and a multi-dimensional playfield (the same instruction can be executed
219:
The name "Befunge" originated from a typing error in an online discussion. While it was designed to be difficult to compile, compilers such as bef2c and Betty have managed to implement the language using various techniques. Befunge programs are characterized by their use of arrows to change control
215:
Befunge was created by Chris
Pressey in 1993 for the Amiga. The language was designed to be as hard to compile as possible, featuring self-modifying code and a multi-dimensional playfield. Despite this, several compilers have been written for the language. The original Befunge-93 specification
204:. It differs from conventional languages in that programs are arranged on a two-dimensional grid. "Arrow" instructions direct the control flow to the left, right, up or down, and loops are constructed by sending the control flow in a cycle. It has been described as "a cross between
400:
order and output as text characters to give "Hello". A space is character number 32 in ASCII, which here is constructed by multiplying 4 and 8, before being output as text. The remaining code then outputs "World!" in a similar way, followed by ASCII character 10 (a
329:
The technique of using arrows to change control flow is demonstrated in the random number generator program below. The
Befunge instruction pointer begins in the upper left corner and will travel to the right if not redirected. Following the arrows around, the
488:!dlrow ,olleHH"). Then the "_" operation will pop the duplicated value, and go right if it's a zero, left otherwise. (This assumes a compliant interpreter that "returns" 0 when popping an empty stack.) When it goes left, it pops and prints the top value as an
244:. Nevertheless, a number of compilers have subsequently been written. A number of extensions to the original "Befunge-93" specification also exist, most notably Funge-98, which extends the concept to an arbitrary number of dimensions and can be
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character. It then duplicates the next character and loops back to the "_" test, continuing to print the rest of the stack until it is empty and so the next value popped is 0, at which point "@" ends the program.
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treat strings as comments in contexts where the values are not used. Similarly, in
Befunge, there is no comment syntax: to embed documentation in the code, the programmer simply routes the control flow
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The etty compiler, for example, treats every possible straight line of instructions as a subprogram, and if a 'p' instruction alters that subprogram, that subprogram is recompiled. This variation on
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results in a much better advantage over an interpreter, since many instructions can be executed in native code without making intervening decisions on the 'direction' register.
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The
Befunge-93 specification restricts each valid program to a grid of 80 instructions horizontally by 25 instructions vertically. Program execution which exceeds these limits
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instructions send the instruction pointer in random cardinal directions until the pointer hits a digit, pushing it to the stack. Then the arrows navigate to the
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ordering means that "H" is now the top of the stack and will be the first printed, "e" is second, and so on. To print the characters, the program enters a
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limited programs to an 80x25 grid, and while not Turing-complete, subsequent extensions like Funge-98 expanded the concept to achieve Turing completeness.
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Nevertheless, these obstacles have been overcome, to some degree, and
Befunge compilers have been written using appropriate techniques.
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275:. Since a Befunge-93 program can only have a single stack and its storage array is bounded, the Befunge-93 language is not
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to output the digit from the stack and return the pointer to the first directional randomiser. There is no
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flow, and they can produce outputs like random number sequences or classic "Hello, World!" messages.
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The following code is a slightly more complicated version. It adds the ASCII character 10 (a
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to a corresponding point on the other side of the grid; a
Befunge program is in this manner
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to terminate this program, so it produces an endless stream of random numbers from 1 to 9.
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operating simultaneously on the same space. Befunge-extensions and variants are called
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Most one-dimensional programming languages require some syntactic distinction between
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that first duplicates the top value on the stack (so now the stack would look like "
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Start string mode: push each character's ASCII value all the way up to the next
24:
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Logical NOT: Pop a value. If the value is zero, push 1; otherwise, push zero.
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character) to the stack, and then pushes "!dlrow ,olleH" to the stack. Again,
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The bef2c compiler included with the standard
Befunge-93 distribution uses
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903:, then push ASCII value of the character at that position in the program
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the "comment" area, so that the text in that area is never executed.
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The language was originally created by Chris
Pressey in 1993 for the
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in an online discussion, where the word 'before' was intended.
18:
862:
A "put" call (a way to store a value for later use). Pop
392:. First the letters "olleH" are pushed onto the stack as
232:, as an attempt to devise a language which is as hard to
998:– PlayStation programming game using a similar language
832:
Pop value and output as an integer followed by a space
895:
A "get" call (a way to retrieve data in storage). Pop
665:, then push the remainder of the integer division of
405:
character, moving the output cursor to a new line).
882:) in the program to the character with ASCII value
769:Pop a value; move right if value=0, left otherwise
171:
151:
136:
126:
49:. Unsourced material may be challenged and removed.
923:Ask user for a character and push its ASCII value
960:— although that distinction may be as trivial as
396:numbers. These are then popped from the stack in
779:Pop a value; move down if value=0, up otherwise
388:The following code is an example of the classic
1173:
8:
759:Start moving in a random cardinal direction
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1099:: CS1 maint: numeric names: authors list (
16:2-dimensional esoteric programming language
1180:
1166:
1158:
964:'s rule that any character not in the set
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109:Learn how and when to remove this message
842:Pop value and output as ASCII character
822:Pop value from the stack and discard it
1315:Non-English-based programming languages
1028:
1092:
1320:Programming languages created in 1993
7:
1310:Stack-oriented programming languages
812:Swap two values on top of the stack
802:Duplicate value on top of the stack
47:adding citations to reliable sources
1148:Befunge-93 Reference Implementation
913:Ask user for a number and push it
14:
546:Push this number onto the stack.
1281:
1280:
1260:Shakespeare Programming Language
874:, then change the character at (
23:
304:in four different directions).
34:needs additional citations for
1305:Esoteric programming languages
1189:Esoteric programming languages
1:
968:is a comment. Languages like
202:esoteric programming language
1250:One-instruction set computer
1053:. 1997-11-04. Archived from
534:Befunge-93 instruction list
236:as possible. Note that the
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507:"!dlrow ,olleH"
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1143:Befunge-93 Specification
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407:
344:
319:just-in-time compilation
852:Bridge: Skip next cell
1153:Funge-98 Specification
631:Integer division: Pop
390:"Hello World!" program
347:v>>>>>v
325:Sample Befunge-93 code
1114:Oerjan (2014-01-18).
1075:Ais523 (2008-12-18).
1051:"The Befunge FAQ v.4"
647:, rounded towards 0.
192:is a two-dimensional
606:Multiplication: Pop
250:instruction pointers
43:improve this article
1037:"Befunge – Esolang"
719:Start moving right
242:self-modifying code
240:command allows for
137:First appeared
123:
749:Start moving down
729:Start moving left
709:, otherwise zero.
693:Greater than: Pop
449:"World!"
291:is derived from a
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950:
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701:, then push 1 if
581:Subtraction: Pop
422:"Hello"
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1077:"Chris Pressey"
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1137:External links
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1116:"Talk:Befunge"
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556:Addition: Pop
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265:"wraps around"
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1057:on 2001-04-17
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312:threaded code
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269:topologically
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246:multithreaded
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172:Influenced by
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132:Chris Pressey
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63:
60: –
59:
55:
54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
1225:Iota and Jot
1204:
1123:. Retrieved
1119:
1109:
1084:. Retrieved
1080:
1070:
1059:. Retrieved
1055:the original
1045:
1031:
978:
966:+-<>,.
954:comment text
951:
933:End program
900:
896:
883:
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871:
867:
863:
706:
702:
698:
694:
670:
666:
662:
658:
657:Modulo: Pop
644:
640:
639:, then push
636:
632:
619:
615:
614:, then push
611:
607:
594:
590:
589:, then push
586:
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569:
565:
564:, then push
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387:
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293:typing error
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99:January 2012
96:
86:
79:
72:
65:
53:
41:Please help
36:verification
33:
958:source code
299:Compilation
194:stack-based
163:/Befunge-93
1299:Categories
1270:Whitespace
1125:2014-01-23
1086:2014-01-23
1061:2014-01-23
1023:References
1007:Whitespace
198:reflective
69:newspapers
1210:Brainfuck
991:Brainfuck
962:Brainfuck
474:line feed
403:line feed
287:The word
283:Etymology
254:Fungeoids
128:Developer
58:"Befunge"
1286:Category
1265:Unlambda
1245:Malbolge
1220:INTERCAL
1215:FRACTRAN
1095:cite web
1012:Malbolge
1002:INTERCAL
985:See also
256:or just
210:Lemmings
1240:LOLCODE
1205:Befunge
1200:Beatnik
1120:Esolang
1081:Esolang
940:(space)
289:Befunge
234:compile
224:History
190:Befunge
157:catseye
152:Website
142: (
122:Befunge
83:scholar
1230:JSFuck
979:around
974:Python
870:, and
446:,,,,,,
258:Funges
85:
78:
71:
64:
56:
944:No-op
909:&
490:ASCII
419:,,,,,
394:ASCII
350:12345
273:torus
230:Amiga
206:Forth
182:FALSE
178:Forth
165:.html
161:/node
90:JSTOR
76:books
1255:Piet
1235:Leet
1101:link
1017:Piet
972:and
970:Lisp
956:and
899:and
725:<
715:>
705:>
697:and
661:and
635:and
610:and
585:and
560:and
525:>
498:>
482:loop
478:LIFO
455:>
452:<
428:>
425:<
410:>
398:LIFO
383:<
368:6789
356:>
208:and
144:1993
140:1993
62:news
542:0-9
365:v?v
353:^?^
212:".
159:.tc
45:by
1301::
1118:.
1097:}}
1093:{{
1079:.
866:,
818:$
673:.
522:_@
519::,
501:25
486:\n
458:25
431:48
362:?^
260:.
200:,
196:,
180:,
1181:e
1174:t
1167:v
1128:.
1103:)
1089:.
1064:.
1039:.
929:@
919:~
901:x
897:y
891:g
884:v
880:y
878:,
876:x
872:v
868:x
864:y
858:p
848:#
838:,
828:.
808:\
798::
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785:"
775:|
765:_
755:?
745:v
735:^
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703:b
699:b
695:a
689:`
679:!
671:a
669:/
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653:%
645:a
643:/
641:b
637:b
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627:/
620:b
618:*
616:a
612:b
608:a
602:*
595:a
593:-
591:b
587:b
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577:-
570:b
568:+
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562:b
558:a
552:+
528:^
516:v
513:v
510::
504:*
467:@
464:,
461:*
443:v
440:v
437:,
434:*
416:v
413:v
380:.
377:^
374:v
359:?
340:@
336:.
332:?
238:p
146:)
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
