C# 运算符重载是否像 C++ 一样支持“+=”？

Question

我来自 C++，作为新手使用 C#，刚刚尝试过：

class Class1
{
    int mI = 0;
    string mS = "ab";

    public static Class1 operator + (Class1 obj1, Class1 obj2)
    {
        return new Class1()
        {
            mI = obj1.mI + obj2.mI,
            mS = obj1.mS + obj2.mS
        };
    }

    public static void operator += (Class1 obj1)
    {
        mI += obj1.mI;
        mS += obj1.mS;
    }
}

我发现 operator+= 函数无法编译，说：

error CS1019: Overloadable unary operator expected.

所以 C# 根本不做这种运算符重载？

Answer 1

您可以重载 +，但不能重载 +=，如 per the documentation:

Assignment operators cannot be explicitly overloaded. However, when you overload a binary operator, the corresponding assignment operator, if any, is also implicitly overloaded. For example, += is evaluated using +, which can be overloaded.

因此，如您所见，+= 被视为 x = x + y。这就是为什么不允许重载 += 运算符的原因。

C# 运算符重载是否像 C++ 一样支持“+=”？

Does C# operator overloading support "+=" like C++?

c#

c++

overloading

operator-keyword