簡單的從接口方法結果轉換爲整數

Question

我有接口IBookRepository。該接口的方法CountAllBooks（）返回整數。 如果我裏面方法接收類型對象的值

public object Convert(object value) 

，如果是通過對象的類型IBookRepository爲什麼我不能施展它的CountAllBooks導致像

public object Convert(object value) 
{ 
    int c; 
    if(value is IBookRepository) 
    { 
     c = (int)value.CountAllBooks(); 
    } 
} 

Answer 1

public object Convert(object value) 
{ 
    int c; 
    if(value is IBookRepository) 
    { 
     c = (int)((IBookRepository)value).CountAllBooks(); 
    } 
    return c; 
} 

Answer 2

整數試試這個：

public object Convert(object value) 
{ 
    int c; 
    if(value is IBookRepository) 
    { 
     c = (int)(value as IBookRepository).CountAllBooks(); //casting "object" to "IBookRepository" 
    } 
}