פרק 11.2ב – מערכים ולולאות על עצמים

public static Student MaxStdNoNulls3(Student[] students)
{
    Student maxSt = students[0];
    foreach (Student st in students)
        if (st.GetAge() > maxSt.GetAge())
            maxSt = st;

    return maxSt;
}

public static Student MaxStudent2(Student[] students)
{
    Student maxSt = null;

    foreach (Student st in students)
    {
        if (st is not null &&
            (maxSt is null || st.GetAge() > maxSt.GetAge()))
            maxSt = st;
    }

    return maxSt;
}

public static Student MaxStudent4(Student[] students)
    => students.MaxBy(st => st.GetAge()); // הוזכר בלבד, לא לפתרון בגרות

internal class Customer
{
    private string name;
    private string telNum;
    private int age;

    public Customer(string name, string telNum)
    {
        this.name = name;
        this.telNum = telNum;
    }

    public int GetAge() => age;
    public string GetName() => name;
    public string GetTelNum() => telNum;
}

internal class Store
{
  private Customer[] arrCust;

  private int current; //יחזיק את האינדקס של התא הריק הראשון

  public Customer[] GetArrCust() { return arrCust; }

  public Store()
  {
    arrCust = new Customer[100];
    current = 0;
  }

  public void AddCus(Customer customer)
  {
    //arrCust[current++] = customer; // short version
    arrCust[current] = customer; // current is the index of the first empty cell
    current++; // current is the index of the next empty place
  }

  public Customer RemoveCust(int ind)
  {
    if (ind >= current || ind < 0)
      return null;
    
      Customer customer = arrCust[ind];
    //0 1 2| current == 3
    //A B C| 
    for (int i = ind; i < current - 1; i++) // index out of range exception תמיד צריך להיזהר מזה 
      arrCust[i] = arrCust[i + 1];
    // B C C

    arrCust[current - 1] = null; 
    // B C null

    current--;
    return customer;
  }


  // הדגמת current: לא רצים עד Length אלא רק עד current
  public string YoungestName()
  {
    Customer theBest = arrCust[0];
    for (int i = 1; i < current; i++)
      if (arrCust[i].GetAge() < theBest.GetAge())
        theBest = arrCust[i];

    return theBest.GetName();
  }
}

// זו הגרסה החיצונית לפי ניסוח השאלה
public string Bomba(Store s, int num)
{
    var res = s.GetArrCust()[num];
    if (res == null)
        return "no";

    return res.GetTelNum();
}