重載的ToString未出現在智能感知中

Question

我正在瀏覽教程youtube。在8:04指導員將本地方法附加到重載的ToString，當我嘗試做同樣的事情時，我在intellisense中看不到重載的方法。

public class Person 
    { 
     public string FirstName { get; set; } 
     public string LastName { get; set; } 
     public DateTime StartDate { get; set; } 
     public int Rating { get; set; } 

     public override string ToString() 
     { 
      return string.Format("{0} {1}", FirstName, LastName); 
     } 

     public string ToString(PersonFormat format) 
     { 
      return format(this); 
     } 

我嘗試添加關鍵字覆蓋太不work.Looks像我的地方失去了一些東西。

Answer 1

這是因爲var隱藏了person的實際類型，當通過PersonListBox.Items訪問時，它是對象。以下作品：

foreach(Person person in PersonListBox.Items) 
{ 


} 

雖然：

foreach(var person in PersonListBox.Items) 
{ 
    // person is object. It doesn't have the method you want to call. 
    // it even doesn't have FirstName or LastName 
    // try person. and you can clearly see it only has the common 
    // object methods. 
} 

提示：您還可以使用foreach(var p in PersonListBox.Items.OfType<Person>())