Trying to check a valid email using Lex, getting "Undefined definition" error instead - lex

Question

I'm trying to create a simple program using Lex that checks if a given email address is valid or not. This is how I'm actually trying to achieve this:
Declarations section
%{
#include <stdio.h>
#include <string>
int correct = 0;
string email;
void write_data(string email, int correct);
/* Alias section */
name [a-zA-Z]
special [-_%+-]
digit [0-9]
domain [a-z]\.[a-z]{2,5}
email {name}+({digit} | {special})*#{domain}{1}
%}
Rules section
%%
{email} {correct = 1;}
%%
Programs section
int main(int argc, char* argv[])
{
if(argc == 2){
yyin = fopen(argv[1], "r");
email = yyin.getline();
if(yyin == NULL){
printf("Couldn't open %s file\n", argv[1]);
exit(-1);
}
}
else{
yyin = stdin;
email = yytext;
}
correct = 0;
yylex();
write_data(email, correct);
return 0;
}
void write_data(string email, int correct)
{
if(correct == 1)
printf("Email %s is correct\n", correo);
else
printf("Email %s is not correct\n", correo);
}
I'm trying to invoke the Lex tool using
lex template.l
And I'm getting the following error:
template.h:40: undefined definition {email}
I've been trying for a while already but I couldn't even run Lex on it so I don't know what could be wrong.

Answer 1

I figured it out for anyone interested. You MUST place the aliases out of the first %{%} section. The result of the Declaration section is as follows:
%{
#include <stdio.h>
#include <string>
int correct = 0;
string email;
void write_data(string email, int correct);
%}
/* Alias section */
name [a-zA-Z]
special [-_%+-]
digit [0-9]
domain [a-z]\.[a-z]{2,5}
email {name}+({digit} | {special})*#{domain}{1}