《编译原理》 练习 3.5.3

%option noyywrap

%{
#include <stdio.h>

void showhelp(char* argv[]);
void translated(const char* t);

%}

%%

^("float")/([ ]|[\t]|[\n]) { translated("double"); }
[ ]("float")/([ ]|[\t]|[\n]) { translated(" double"); }
[\t]("float")/([ ]|[\t]|[\n]) { translated("    double"); }

%%

void showhelp(char* argv[])
{
  printf("Usage %s [input_filename] [output_filename]\n",argv[0]);
}

void translated(const char* t)
{
  fprintf(yyout,"%s",t);
}


int main(int argc,char* argv[])
{
  FILE* inputfile;
  FILE* outputfile;

  if(argc != 3)
    {
     showhelp(argv);
     return 0;
    }
  inputfile = fopen(argv[1],"r");
  outputfile = fopen(argv[2],"w");

  if(inputfile && outputfile)
    {
     yyin = inputfile;
     yyout = outputfile;
     while(yylex());
    }
  else
    {
     printf("open file failed.\n");
    }
  return 0;
}