如何将整数创建为字符代码常量? [英] How is a integer created as a character code constant?

问题描述

我正在为 integer/1 使用 SWI-Prolog.

I am building some test cases for integer/1 using SWI-Prolog.

ISO/IEC 13211-1 给出了 integer 的 BNF 定义，整数的替代方法之一是 字符代码常量.

ISO/IEC 13211-1 gives a BNF definition for integer and one of the alternatives for integer is for a character code constant.

我能够使用 integer/1 创建和测试所有其他替代方案的示例，但是对于 character code constant 我无法创建有效示例.(见下文)

I am able to create and test examples of all the other alternatives using integer/1 but for character code constant I cannot create a valid example. (see below)

如何使用 整数/1?

How is an integer as a character code constant created that will return true using integer/1?

回答

感谢@false.

integer(0'0).
true.

integer(0'9).
true.

integer(0'a).
true.

integer(0'\n).
true.

<小时>

实用性

X is 0'\n.
X = 10.

X is 0b010101.
X = 21.

X is 0xFFF1.
X = 65521.

X is 0o7423.
X = 3859.

感谢 j4n bur53通过@false 的链接

and thanks to j4n bur53 via link from @false

对于 SWI-Prolog，除了 2,8 或 16 之外，还可以使用其他基数.

with SWI-Prolog other radix can be used besides 2,8, or 16.

X is 5'1234012340.
X = 3032220.

X is 32'123456789ABCDEFGHIJKLMNOPQRSTU.
X = 47525417447024678661670292427038339608998846.

<小时>

我尝试了什么

---

What I tried

integer("0").
false.

integer('0').
false.

integer(`0`).
false.

integer("1").
false.

integer('1').
false.

integer(`1`).
false.

<小时>

ISO

国际标准 ISO/IEC 13211-1 第一版 1995-06-01
信息技术 - 编程语言 - Prolog
第 1 部分:通用核心

INTERNATIONAL STANDARD ISO/IEC 13211-1 First edition 1995-06-01
Information technology - Programming languages - Prolog
Part 1: General Core

国际标准 ISO/IEC 13211-1:1995
技术勘误1
发表于 2007-11-15

INTERNATIONAL STANDARD ISO/IEC 13211-1:1995
TECHNICAL CORRIGENDUM 1
Published 2007-11-15

国际标准 ISO/IEC 13211-1:1995
技术勘误2
发表于 2012-02-15

INTERNATIONAL STANDARD ISO/IEC 13211-1:1995
TECHNICAL CORRIGENDUM 2
Published 2012-02-15

integer 的 BNF

integer token (* 6.4.4 *) =  
    integer constant (* 6.4.4 *)
  | character code constant (* 6.4.4 *)
  | binary constant (* 6.4.4 *)
  | octal constant (* 6.4.4 *)
  | hexadecimal constant (* 6.4.4 *) ;

字符代码常量

character code constant (* 6.4.4 *) =  
  "0" , single quote char (* 6.5.5 *), single quoted character (* 6.4.2.1 *) 

我怀疑 ISO/IEC 13211-1 中的 BNF 是错误的，但检查 CORRIGENDUM 显示没有更正.

I suspect the BNF is wrong in ISO/IEC 13211-1 but checking the CORRIGENDUM shows no corrections.

整数测试用例

% <integer constant> examples

number(1). 
% true.

number(0).
% true.

number(01).
% true.

number(12345678901234567890123456789012345678901234567890).
% true.

% <character code constant> examples

% ???

% <binary constant> examples

number(0b0).  
% true.

number(0b10101010101010101010101010101010101010101010101010). 
% true.

integer(0b2).
% ERROR: Syntax error: Illegal number
% ERROR: integer
% ERROR: ** here **
% ERROR: (0b2) .

% <octal constant> examples

integer(0o7). 
% true.

integer(0o1234567012345670123456701234567012345670123456701234567). 
% true.

integer(0o8).
% ERROR: Syntax error: Illegal number
% ERROR: integer
% ERROR: ** here **
% ERROR: (0o8) . 

% <hexadecimal constant>

integer(0x0). 
% true.

integer(0xF). 
% true.

integer(0xf). 
% true.

integer(0x123456789ABCDEF012345670123456789ABCDEF012345670123456789ABCDEF). 
% true.

integer(0xG).
% ERROR: Syntax error: Illegal number
% ERROR: integer
% ERROR: ** here **
% ERROR: (0xG) . 

推荐答案

这是在评论中被 false 回答的.
在此处重新发布，以便其他人可以看到存在的答案.

This was answered by false in a comment.
Reposting here so that others can see an answer exist.

integer(0'0).
true.

integer(0'9).
true.

integer(0'a).
true.

integer(0'\n).
true.

这篇关于如何将整数创建为字符代码常量?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！