EBNF标识符定义 [英] EBNF Definition of Identifier

问题描述

标识符的EBNF定义为(a-zA-Z, _ ){a-zA-Z0-9, _ }.有人可以解释这个定义，并根据这个定义给我一个有效的标识符.

The EBNF definition of an identifier is (a-zA-Z, _ ){a-zA-Z0-9, _ }. Can someone explain this definition and give me a valid identifier by this definition.

推荐答案

The syntax of EBNF like languages differ a lot. Normally I would define something like this:

letter = "a" | "b" | ... | "z" | "A" | ... | "Z";
digit = "0" | "1" | "2" | ... | "9";
identifier = letter , { letter | digit | "_" } ;

您的表单看起来像 EBNF 和 regex . 如果我不知道我们在说哪种语言，很难说这意味着什么.

Your form looks like a mixture of EBNF and regex. It is hard to tell what this means if I don't know which language we are talking about.

但是，仅凭猜测，我会说它描述的是类似于C的标识符(例如变量名)，例如"myVar_0123ab". 标识符必须以字母或下划线"_"开头，后跟字母，下划线和数字.

But by pure guessing, I would say it describes a C-like identifier (e.g. variable name) like "myVar_0123ab". The identifier has to start with a letter, or an underline '_', followed by letters, underlines and digits.

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