C＃结构体：未分配的本地变量？ [英] C# Structs: Unassigned local variable?

问题描述

从文档：

不同于类，结构可以不使用new运算符实例化。

Unlike classes, structs can be instantiated without using a new operator.

那么，为什么我收到这个错误：

So why am I getting this error:

未分配的局部变量的使用X

Use of unassigned local variable 'x'

当我尝试这样做。

        Vec2 x;
        x.X = det * (a22 * b.X - a12 * b.Y);
        x.Y = det * (a11 * b.Y - a21 * b.X);

其中， VEC2 X 是一个结构？

推荐答案

那么，X和Y属性（而不是字段）？如果是这样，这就是问题所在。直到在所有字段X 肯定是分配的，你不能调用任何方法或属性。

Well, are X and Y properties (rather than fields)? If so, that's the problem. Until all the fields within x are definitely assigned, you can't call any methods or properties.

有关实例

public struct Foo
{
    public int x;
    public int X { get { return x; } set { x = value; } }
}

class Program
{
    static void Main(string[] args)
    {
        Foo a;
        a.x = 10; // Valid

        Foo b;
        b.X = 10; // Invalid
    }
}

是 VEC2 您自己的类型？你可以访问所涉及的领域，或仅属性？

Is Vec2 your own type? Do you have access to the fields involved, or only the properties?

如果这是你自己的类型，我会的强烈的敦促你尝试坚持不变的结构。我知道托管DirectX具有越来越接近尽可能最佳性能的一些可变的结构，但是这是在陌生的情况下，这样的成本 - 和差很多，说实话

If it's your own type, I would strongly urge you to try to stick to immutable structs. I know managed DirectX has some mutable structs for getting as close to optimal performance as possible, but that's at the cost of strange situations like this - and much worse, to be honest.

我会亲自给该结构的构造以X和Y：

I would personally give the struct a constructor taking X and Y:

 Vec2 x = new Vec2(det * (a22 * b.X - a12 * b.Y),
                   det * (a11 * b.Y - a21 * b.X));

这篇关于C＃结构体：未分配的本地变量？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！