自顶向下的语法分析：递归下降法.doc

实验二：自顶向下的语法分析：递归下降法1、实验目的：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。2、实验要求：文法（教材199页）（1）把词法分析作为语法分析的子程序实现（5分）（2）独立的语法分析程序（4分）（3）输入串以#结束，输出成功（success）或出错（error）、指出出错位置（行、列以及错误类型）#include #include #include #include #define MAX 1024using namespace std;string DataType = int, bool, char, void;string KeyWords = if, else, do, while, for, break, in, continue, goto,switch, case, default, foreach, try, catch, finally, throw, return;string Operator = +, -, *, /, %, &, |, , =, =, =, !=, , &, |, , =, +=, -=, *=, /=, %=, &=, |=, =, =;char Seperator = , ., (, ), , , ;, , , , ?, :;struct Identitystring value;int type;ifstream inFile(D:output.txt);int row = 1;Identity ID10000;int nWord = 0;void Expression()string word;int syn;inFile word syn;if(syn = 71)string tmp1;int tmp2;inFile tmp1 tmp2;if(tmp2 != 199)if(tmp2 = 30 & tmp2 tmp1 tmp2;if(tmp2 = 71)inFile tmp1 tmp2;if(tmp2 != 199)cout error occurs in row row , miss ;! endl;elsecout error occurs in row row , miss identity! endl;elsecout error occurs in row row , miss operator! endl;int look(string value)int i;for(i=0; i word syn;if(word = #)row+;elseif(syn 0 & syn tmp1 tmp2;if(tmp2 = 71)int index = look(tmp1);/IDindex.type = syn;inFile tmp1 tmp2;if(tmp2 != 199)if(tmp1 = =)Expression();elsecout error occurs in row row , miss ;! endl;elsecout error occurs in row row , miss identity! word syn;if(word = =)Expression();elsecout error occurs in r