Stub program to validate an E-mail address

email_validate.cpp

#include <cstdio.h>

int main(int argc, const char* argv[]) {
  if(argc != 2)
    return 1;
    
  const char* email = argv[1];
  
  // A valid E-mail address is actually quite complex.  You will be writing a function will validate a
  // subset of these rules.  Here, a valid E-mail address will be defined by the following grammar:
  //
  // email :- localpart '@' domain
  // localpart :- piece | localpart '.' piece
  // piece :- [a-zA-Z0-9!#$%&'*+-/=?^_`{|}~]+
  // domain :- hostnamepart | domain '.' hostnamepart
  // hostnamepart :- [a-zA-Z0-9-]+
  //
  // The following restrictions also apply:
  //  domain:    Cannot be more than 253 characters
  //  localpart: Cannot be more than 64 characters
  //  email:     Cannot be more than 254 characters

  // TODO:  Return 0 for a bad E-mail address, return 1 for a good one
  return 0;
}