%{/* * ch2-03.l * * The word counter example for multiple files * */unsigned long charCount = 0, wordCount = 0, lineCount = 0;#undef yywrap	/* sometimes a macro by default */%}word [^ \t\n]+eol  \n%%{word}	{ wordCount++; charCount += yyleng; }{eol}	{ charCount++; lineCount++; }.	charCount++;%%char **fileList;unsigned currentFile = 0;unsigned nFiles;unsigned long totalCC = 0;unsigned long totalWC = 0;unsigned long totalLC = 0;main(argc,argv)int argc;char **argv;{        FILE *file;        fileList = argv+1;        nFiles = argc-1;        if (argc == 2) {		/*		 * we handle the single file case differently from		 * the multiple file case since we don't need to		 * print a summary line		 */		currentFile = 1;		file = fopen(argv[1], "r");		if (!file) {			fprintf(stderr,"could not open %s\n",argv[1]);			exit(1);		}		yyin = file;        }        if (argc > 2)		yywrap();	/* open first file */	yylex();        /*         * once again, we handle zero or one file	 * differently from multiple files.         */        if (argc > 2) {		printf("%8lu %8lu %8lu %s\n", lineCount, wordCount,			charCount, fileList[currentFile-1]);		totalCC += charCount;		totalWC += wordCount;		totalLC += lineCount;		printf("%8lu %8lu %8lu total\n",totalLC, totalWC, totalCC);	} else		printf("%8lu %8lu %8lu\n",lineCount, wordCount, charCount);	return 0;}/* * the lexer calls yywrap to handle EOF conditions (e.g., to * connect to a new file, as we do in this case.) */yywrap(){	FILE *file;	if ((currentFile != 0) && (nFiles > 1) && (currentFile < nFiles)) {		/*		 * we print out the statistics for the previous file.		 */		printf("%8lu %8lu %8lu %s\n", lineCount, wordCount,			charCount, fileList[currentFile-1]);		totalCC += charCount;		totalWC += wordCount;		totalLC += lineCount;		charCount = wordCount = lineCount = 0;		fclose(yyin);	/* done with that file */	}	while (fileList[currentFile] != (char *)0) {		file = fopen(fileList[currentFile++], "r");		if (file != NULL) {			yyin = file;			break;		}		fprintf(stderr,			"could not open %s\n",			fileList[currentFile-1]);	}	return (file ? 0 : 1);	/* 0 means there's more input */}