wc.l

%{
#include <stdio.h>
#include <stdlib.h>
int words = 0, lines = 0, chars = 0;
%}

%%
\n              { chars += yyleng; lines += 1; };
[ \t]+          { chars += yyleng; };
[^ \t\n]+       { chars += yyleng; words += 1; };

%%
// lex -o wc.c wc.l && cc wc.c -o wc

int yywrap() {
    return 1;
}

int main(int argc, char* argv[]) {
    char *input = "";
    if (argc == 2) {
        input = argv[1];
        yyin = fopen(input, "r");
    }
    yylex();
    printf("%8d%8d%8d %s\n", lines, words, chars, input);
    return 0;
}