c语言语法分析器，输入表达式 输出表达式语法是否正确 -c language parser, input output expression expression syntax is correct

编制一个递归下降分析程序，实现对词法分析程序所提供的单词序列的语法检查和结构分析。-The preparation of a recursive descent parser, syntax checking and word structure to achieve lexical analysis program provided by sequence analysis.