Question

public class Form1 : System.Windows.Forms.Form
{
    private void eachCornerPix (object sender, PaintEventArgs e, out float Wx, out float Wy, out float Vx, out float Vy)
    {
        Graphics g = this.CreateGraphics();
        Pen penBlu = new Pen(Color.Blue, 2);
        SolidBrush redBrush = new SolidBrush(Color.Red);
        int width = 2;    // 1 pixel wide in x
        int height = 2;
        float [] Wxc = {0.100f, 5.900f, 5.900f, 0.100f}; 
        float [] Wyc = {0.100f, 0.100f, 3.900f, 3.900f}; 
        for (int i = 0; i<3; i++)
        {
            Wx = Wxc[i];
            Wy = Wyc[i];
            Vx = ((Wx - WXmin)*((VXmax-VXmin)+VXmin)/(WXmax-WXmin));  
    Vy = ((Wy - WYmin)*(VYmax-VYmin)/(WYmax-WYmin)+VYmin); 
    Console.WriteLine("eachCornerPix Vx= {0}", Vx);
    Console.WriteLine("eachCornerPix Vy= {0}", Vy);
    g.FillRectangle(redBrush, Vx, Vy, width, height);
            g.Dispose();
        }
    }
}

所需效果：使用数组值（Wxc，Wyc）并将它们重新分配给Wx和Wy。然后用 Wx和Wy作为计算Vx和Vy的组件。我的最终目标......一旦编译问题得到解决，就是传递列出的每个数组值使用这种方法。这应该允许绘制4个xy点对。

错误：

pass1.cs(51,18): error CS0177: The out parameter 'Wx' must be assigned to before control leaves the current method
pass1.cs(51,18): error CS0177: The out parameter 'Wy' must be assigned to before control leaves the current method
pass1.cs(51,18): error CS0177: The out parameter 'Vx' must be assigned to before control leaves the current method
pass1.cs(51,18): error CS0177: The out parameter 'Vy' must be assigned to before control leaves the current method

Answer 1

我认为错误信息非常明显。只需加上

Wx = Wy = 0;
Vx = Vy = 0;

位于方法的顶部。我可以从你的逻辑中看出，代码保证在返回之前将值设置为某个值，但编译器用来确定它的静态分析相对简单，有时候有些悲观。

Answer 2

将它放在方法的开头：

Wx = 0f;
Wy = 0f;
Vx = 0f;
Vy = 0f;

错误CS0177：必须在控制离开当前方法之前指定out参数'Wx'

2 个答案: