flex

 1 %option noyywrap
 2 %{
 3 #include <stdio.h>
 4 int chars = 0;
 5 int words = 0;
 6 int lines = 0;
 7 %}
 8 
 9 %%
10 
11 [a-zA-Z]+    { words++; chars += strlen(yytext); }
12 \n            { chars++; lines++; }
13 .            { chars++; }
14 
15 %%
16 
17 int main(int argc, char **argv)
18 {
19     yylex();
20     printf("%8d%8d%8d\n", lines, words, chars);
21 }