Replacing String with char array[x]

Firmware
3

An alternative to Paul’s suggestions (with the benefit to not overshoot the array boundaries :wink: )

int setEmail(const char* command) {
  int retVal = strncpy(config_data.email, command, sizeof(config_data.email)-1);
  ...
  return retVal; // use the return value to communicate something at least 
                 // somewhat useful like the length of the actually copied string
                 // or the result of the storeConfigVariables() call 
}

works just as well.

Additionally, if you ever want to wipe the content of the array entirely you can use

  memset(config_data.email, 0, sizeof(config_data.email));

consequently I’d add this to storeConfigVariables()

bool storeConfigVariables(const char* email = NULL, bool cleanSlate = false) {
  bool retVal = false;

  if (cleanSlate) {
    memset(config_data, 0, sizeof(config_data));
    config_data.magic = DATA_MAGIC;
  }
  if (email) {
    strncpy(config_data.email, email, sizeof(config_data.email)-1);
  }

  ...

  return retVal;
}