#include <stdio.h>extern int yydebug;extern FILE *yyin, *yyout;extern int MVL_LINNUM;main(argc, argv)int argc;char** argv;{  char* infilename;  /* missing parameter check */      /* yydebug=1; */  /* open files */  /* input file */  if (argc>1){    infilename=(char*)malloc(sizeof(char)*strlen(argv[1])+1);    strcpy(infilename, argv[1]);    if ((yyin=fopen(argv[1],"r"))==NULL){      yyerror("unable to open inputfile");    }        argc--;    argv++;  }else{    infilename=" ";  }  /* output file */  if (argc>1){    if ((yyout=fopen(argv[1],"w"))==NULL){      yyerror("could not open outputfile\n");    }  }  yyparse();  exit(0);}