C# 错误消息 : Cannot Implicitly convert type

Question

下面的代码抛出以下异常:

Error 1 Cannot implicitly convert type 'Clarity.DevTest.Exercises.ChessPosition' to 'System.Collections.Generic.IEnumerable< Clarity.DevTest.Exercises.ChessPosition>'. An explicit conversion exists (are you missing a cast?)

谁能给我解释一下出了什么问题，为什么不能返回结果？

using System;
using System.Collections.Generic;

namespace Clarity.DevTest.Exercises
{
public class Exercise1
{
    public IEnumerable<ChessPosition> GetLegalMoves(ChessPosition rookToMove, ChessPosition friendlyRook, ChessPosition enemyRook1, ChessPosition enemyRook2)
    {

        //create array to hold positions
        ChessPosition[,] coords = new ChessPosition [8,8];
        //set the Rooks into the correct places on the array
        //eg rookToMove.X = 4, rookToMove.Y = 5, "R" would be places in 4,5
        coords[rookToMove.X, rookToMove.Y] = "R";
        coords[friendlyRook.X, friendlyRook.Y] = "F";
        coords[enemyRook1.X, enemyRook1.Y] = "1";
        coords[enemyRook2.X, enemyRook2.Y] = "2";

        //throw new NotImplementedException();

        ChessPosition result = new ChessPosition(4, 5);
        return result;
    }
}

public partial class ChessPosition
{
    public ChessPosition(int x, int y)
    {
        //check to see if out of bounds
        if (x < 1 || x > 8 || y < 1 || y > 8)
        {
            throw new ArgumentException("x and y must be in the range 1-8");
        }
        X = x;
        Y = y;
    }

    public int X { get; set; }
    public int Y { get; set; }
  }
}

Answer 1

您将返回单个 ChessPosition 而不是结果的可枚举集合。

要么返回一个可枚举的集合:

ChessPosition result = new ChessPosition(4, 5);
IEnumerable<ChessPosition> results = new List<ChessPosition>();
results.Add(result);

return results;

或更改您的返回类型:

public ChessPosition GetLegalMoves(
    ChessPosition rookToMove, ChessPosition friendlyRook, ChessPosition 
    enemyRook1, ChessPosition enemyRook2)