foreach loop

I have two questions

1) my interface i have interface called IRegister and within it i have another interface called IPerson, is that right practice?

2) i have two List(IRegister, IPerson) both can have one or more rows.

what is the best way to loop both List? within GetValidationRules?

public interface IRegister 
{
    string FirstName { get; }
    string MiddleName { get; }
    string LastName { get; }
    string EmailAddress { get; }        
    List<IPerson> Student { get; }
}


public static List<ValidationRule> GetValidationRules(List<IRegister> register)
    {
        List<ValidationRule> validationRules = new List<ValidationRule>();  



        foreach (IRegister myregister in register)
        {
            if (string.IsNullOrEmpty(myregister.FirstName))
                validationRules.Add(new ValidationRule("Reg", "Must have aFirst Name"));
            if (string.IsNullOrEmpty(myregister.LastName))
                validationRules.Add(new ValidationRule("Reg", "Must have a Last Name"));
   开发者_Go百科         if (string.IsNullOrEmpty(myregister.EmailAddress))
                validationRules.Add(new ValidationRule("Reg", "Must have a Email Address"));

  IPerson here? how
        }

Um, nested loop at your marker.

foreach (IPerson peep in myregister.Student) { ... }

While I am not 100% sure what you're trying to accomplish based on your question... I am guessing that you're wondering how to iterate through the Student propery of IRegister inside the loop...

public interface IRegister 
{
    string FirstName { get; }
    string MiddleName { get; }
    string LastName { get; }
    string EmailAddress { get; }        
    List<IPerson> Student { get; }
}

public static List<ValidationRule> GetValidationRules(List<IRegister> register)
{
    List<ValidationRule> validationRules = new List<ValidationRule>();  



    foreach (IRegister myregister in register)
    {
        if (string.IsNullOrEmpty(myregister.FirstName))
            validationRules.Add(new ValidationRule("Reg", "Must have aFirst Name"));
        if (string.IsNullOrEmpty(myregister.LastName))
            validationRules.Add(new ValidationRule("Reg", "Must have a Last Name"));
        if (string.IsNullOrEmpty(myregister.EmailAddress))
            validationRules.Add(new ValidationRule("Reg", "Must have a Email Address"));

        foreach (IPerson person in myregister.Student) 
        {
            // Not sure what properties you want to check for because 
            // you didn't show us what the IStudent interface looks like
            // so I will just assume that the IStudent object has a  
            // property for EmailAddress as well

            if (string.IsNullOrEmpty(person.EmailAddress))
                validationRules.Add(new ValidationRule("Reg", "Student must have a Email Address"));
        }
    }
}

The easiest way to loop over all of the IPerson instances is to use SelectMany to flatten the list of IPerson within the IRegister instances. For example

foreach ( var person in register.SelectMany(x => x.Student))  {
  ...
}

This has the effect of creating an IEnumerable<IPerson> which contains all IPerson instances from all of the IRegister values.