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

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


////////////
// emails.l
////////////

%{
#include <stdio.h>
%}

%%
[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]+ {
    printf("EMAIL: %s\n", yytext);
}
^"Secret"$  { printf("Special secret match!"); }
.    ; /*matches any single character */
\n   ; /*matches newline */
%%

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