/** 
 * Read in from a specified file and 
 * print out a list of all the integers in the file
 * 
 * flex -o test.yy.c test.yy
 * gcc -o test test.yy.c -ll
 */

    int count = 0; // the whitespace here is important.(the declaration is tabbed in)

DIGIT       [0-9]

%%

{DIGIT}+        { printf("number: %10d\n", atoi(yytext)); 
                        /*yytex a special character available to the C code
		   contains the text corresponding to the current token:
		   the text matched by the regular expression */
	          }
\n              count++;
.               /* skip all other input */

%%
int main( int argc, char *argv[] ) {
		
    if (argc > 1)
        yyin = fopen( argv[1], "r" ); //where yylex reads its input 
        
    yylex(); // a function of flex that read input till it is exhausted
    printf("There are %d lines in the file.\n", count);
    return 0;
}