変換演算子

暗黙的な変換

public static implicit operator 変換後の型(変換元の型 値1) {
    return 値2;
}

明示的な変換

public static explicit operator 変換後の型(変換元の型 値1) {
    return 値2;
}

明示的な変換の場合は、キャストが指定された時だけ行われる。

暗黙的な変換の例

using System;

class ThreeD {
    int x, y, z;

    public ThreeD(int i, int j, int k) { x = i; y = j; z = k; }

    public static implicit operator double(ThreeD op1) {
        return Math.Sqrt(op1.x * op1.x + op1.y * op1.y + op1.z * op1.z);
    }
}

class ConversionOpDemo {
    static void Main() {
        ThreeD alpha = new ThreeD (12, 3, 4);
        ThreeD beta = new ThreeD (10, 10, 10);
        double dist;

        dist = alpha;
        Console.Write ("Here is dist: " + dist);
        Console.WriteLine ();

        if (beta > dist) {
            Console.WriteLine ("beta is farther from the origin.");
        }
    }
}

明示的な変換の例

using System;

class ThreeD {
    int x, y, z;

    public ThreeD(int i, int j, int k) { x = i; y = j; z = k; }

    public static explicit operator double(ThreeD op1) {
        return Math.Sqrt(op1.x * op1.x + op1.y * op1.y + op1.z * op1.z);
    }
}

class ConversionOpDemo {
    static void Main() {
        ThreeD alpha = new ThreeD (12, 3, 4);
        ThreeD beta = new ThreeD (10, 10, 10);
        double dist;

        dist = (double)alpha;
        Console.Write ("Here is dist: " + dist);
        Console.WriteLine ();

        if ((double)beta > dist) {
            Console.WriteLine ("beta is farther from the origin.");
        }
    }
}