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http://www.monmouth.com/~wstreett/lex-yacc/lex-yacc.html1.工程路径不允许有空格

%{ #include void yyerror(char *); #include "AddLex.h" %}  %%  [0-9]+      {                 yylval = atoi(yytext);                 return INTEGER;             }  [-+/n]      return *yytext;  [ /t]   

%%. printf("match everything except newline/n");/n printf("match newline/n");%%int yywrap(void){ return 1;}int main(void){ printf("begin/n"); yylex(); printf("end"); return 0;}

%{ #include     int yylex(void);     void yyerror(char *); %}  %token INTEGER  %%  program:         program expr /n         { printf("%d/n", $2); }         |          ;  expr:         INTEGER       

%{ int yylineno=0;%}%%^(.*)/n printf("%4d/t%s", ++yylineno,yytext);%%int yywrap(void){ return 1;}int main(void){ yyin=fopen("input.txt","r"); yylex(); fclose(yyin); return 0;}

digit [0-9]letter [A-Za-z]%{ int count=0;%}%%{letter}({letter}|{digit})* {count++;  printf("number of identifiers=%d/n",count);};%%int yywrap(void){ return 1;}int main(void){ yylex(); return 0; }

/* -*-C-*-  Note some compilers choke on comments on `#line lines.  */#line 3 "bison.simple"/* Skeleton output parser for bison,   Copyright (C) 1984, 1989, 1990 Free Software Foundation, Inc.