具有多个返回参数的C#方法

Question

c#/ .net中是否需要多个返回参数？

public string, string GetFirstNameAndLastName(int id)
{
    var person = from p in People
                 where p.Id = id
                 select p;
    return(p.FirstName, p.LastName);
}

用法:

public void Main(string[] args)
{
    string firstName, lastName;
    (firstName, lastName) = GetFirstNameAndLastName(1);

    Console.WriteLine(firstName + ", " + lastName);
}

Answer 1

您可以使用C#4.0中的Tuple以轻量级方式实现此目的

public Tuple<string, string> GetFirstNameAndLastName(int id)
{
   var person = from p in People
             where p.Id = id
             select p;
   return new Tuple<string, string>(p.FirstName, p.LastName);

   // OR
   // return Tuple.Create(p.FirstName, p.LastName);
}

System.Tuple 还有与F#本机元组类型互操作的好处(好吧,它是F#的本机元组类型,恰好是F#特定的语法支持,用于声明返回它们的元组和函数).

鉴于多种方法在这里的存在:System.Tuple,多out参数或者返回POCO与FirstName和LastName性质,我怀疑安德斯·海尔斯伯格很可能不会增加对多个返回值的明确支持.

Answer 2

不,只需使用out参数.

public void GetFirstNameAndLastName(int id, out string first, out string last)
{
    var person = from p in People
                 where p.Id = id
                 select p;
    first = p.FirstName;
    last = p.LastName;
}