词法分析器功能的输入源，按照构词规则成一系列字的符号。Word是一个独立意义的语言，包括关键字，标识符，运算符，行业经营者和常量等的最小单位-Lexical analyzer function input source, in accordance with the rules of word formation into a series of word symbols. Word is the smallest unit of an independent meaning language, including keywords, identifiers, operators, industry operators and constants, etc.