如何从一个函数返回2个值

Question

我有一个计算两个位置的函数,我想得到它们两个,有没有办法从同一个函数返回两个值,而不是把它们变成一个数组.我认为有一些争论或类似的东西... tnx.我的代码:

public static int Location(int p_1, int p_2, int p_3, int p_4)
{
  int  XLocation = p_2 - p_1;
  int YLocation = p_4-p_3;
  return XLocation,YLocation;
}

public void Print()
{
}

Answer 1

有多种方法:

1)使用:

public KeyValuePair<int, int> Location(int p_1, int p_2, int p_3, int p_4)
{                 
    return new KeyValuePair<int,int>(p_2 - p_1, p_4-p_3);
}

要么

static Tuple<int, int> Location(int p_1, int p_2, int p_3, int p_4)
{
    return new Tuple<int, int>(p_2 - p_1, p_4-p_3);
}

2)使用自定义类 Point

public class Point
{
    public int XLocation { get; set; }
    public int YLocation { get; set; }
}

public static Point Location(int p_1, int p_2, int p_3, int p_4) 
{    
     return new Point 
     {
        XLocation  = p_2 - p_1;
        YLocation = p_4 - p_3;
     }      
 }

3)使用out关键字:

   public static int Location(int p_1, int p_2, int p_3, int p_4, out int XLocation, out int YLocation)
   {
        XLocation = p_2 - p_1;    
        YLocation = p_4 - p_3;
   }

以下是这些方法的比较:多次返回值.

最快的方式(最佳性能)是:

public KeyValuePair<int, int> Location(int p_1, int p_2, int p_3, int p_4)
{                 
    return new KeyValuePair<int,int>(p_2 - p_1, p_4-p_3);
}

Answer 2

使用结构或类:

public struct Coordinates
{
    public readonly int x;
    public readonly int y;

    public Coordinates (int _x, int _y) 
    {
        x = _x;
        y = _y;
    }
}

public static Coordinates Location(int p_1, int p_2, int p_3, int p_4) 
{
    return new Coordinates(p_2 - p_1, p_4 - p_3);
}

我发现它比使用out关键字更漂亮.

Answer 3

您不能以这种方式返回2个值.但是您可以将变量作为输出变量传递,如下所示:

  public static void Location(int p_1, int p_2, int p_3, int p_4, out int XLocation, out int YLocation)
{
    XLocation = p_2 - p_1;

    YLocation = p_4-p_3;
}

然后你只需要将目标变量传递给方法:

int Xlocation, YLocation;
Location(int p_1, int p_2, int p_3, int p_4, out int XLocation, out int YLocation);

它会用计算值填充它们.

Answer 4

从 C# 7.0 开始，您可以像这样使用元组：

(string, string) LookupName(long id) // tuple return type
{
    ... // retrieve first, middle and last from data storage
    return (first, last); // tuple literal
}

var names = LookupName(id);
WriteLine($"found {names.Item1} {names.Item2}.");

甚至名称：

(string first, string middle, string last) LookupName(long id)

var names = LookupName(id);
WriteLine($"found {names.first} {names.last}.");

可在此处找到更多信息。