/////////////
// Compile
/////////////

flex length.l
g++ lex.yy.c -ll -Wno-deprecated


////////////
// length.l
////////////

%{
#include <stdio.h>
#include <iostream>
using namespace std;
%}

%%
[a-zA-Z0-9_]+  {
    int n = yyleng;
    cout << yytext << ": " << n << endl;
}
[ \t]+    ;    /*ignore tabs and spaces, otherwise they call ECHO;*/
\n        { return 0; } /*end the program, do not ask for more input */
%%

int main(void) {
    yylex();
    return 0;
}