C# 通過KeyPress事件，限制TextBox僅能輸入數字

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撰寫KeyPress事件，實現限制輸入數字功能

(char)48 --> 數字 0    (char)49 --> 數字 1
(char)50 --> 數字 2    (char)51 --> 數字 3
(char)52 --> 數字 4    (char)53 --> 數字 5
(char)54 --> 數字 6    (char)55 --> 數字 7
(char)56 --> 數字 8    (char)57 --> 數字 9
(char) 8 --> backspace (char)46 --> . (point)
更多相關對應參考Ascii table



private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == (Char)48 || e.KeyChar == (Char)49 ||
        e.KeyChar == (Char)50 || e.KeyChar == (Char)51 ||
        e.KeyChar == (Char)52 || e.KeyChar == (Char)53 ||
        e.KeyChar == (Char)54 || e.KeyChar == (Char)55 ||
        e.KeyChar == (Char)56 || e.KeyChar == (Char)57 ||
        e.KeyChar == (Char)8  || e.KeyChar == (Char)46)
    {
        e.Handled = false;  //允許textBox1物件接受按鍵
    }
    else
    {
        e.Handled = true;   //不允許textBox1物件接受按鍵
    }
}

C# 已知空間三點，求圓心座標

C#

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C# 已知空間三點，求圓心座標

public class PT
{
    public double x { get; set; }
    public double y { get; set; }
    public double z { get; set; }
};

PT FindCenterPoint(PT pd, PT pd2, PT pd3)
{
    double a1, b1, c1, d1;
    double a2, b2, c2, d2;
    double a3, b3, c3, d3;

    PT pd_center = new PT();
    a1 = (pd.y * pd2.z - pd2.y * pd.z - pd.y * pd3.z + pd3.y * pd.z + pd2.y * pd3.z - pd3.y * pd2.z);
    b1 = -(pd.x * pd2.z - pd2.x * pd.z - pd.x * pd3.z + pd3.x * pd.z + pd2.x * pd3.z - pd3.x * pd2.z);
    c1 = (pd.x * pd2.y - pd2.x * pd.y - pd.x * pd3.y + pd3.x * pd.y + pd2.x * pd3.y - pd3.x * pd2.y);
    d1 = -(pd.x * pd2.y * pd3.z - pd.x * pd3.y * pd2.z - pd2.x * pd.y * pd3.z + pd2.x * pd3.y * pd.z
         + pd3.x * pd.y * pd2.z - pd3.x * pd2.y * pd.z);

    a2 = 2 * (pd2.x - pd.x);
    b2 = 2 * (pd2.y - pd.y);
    c2 = 2 * (pd2.z - pd.z);
    d2 = pd.x * pd.x + pd.y * pd.y + pd.z * pd.z - pd2.x * pd2.x - pd2.y * pd2.y - pd2.z * pd2.z;

    a3 = 2 * (pd3.x - pd.x);
    b3 = 2 * (pd3.y - pd.y);
    c3 = 2 * (pd3.z - pd.z);
    d3 = pd.x * pd.x + pd.y * pd.y + pd.z * pd.z - pd3.x * pd3.x - pd3.y * pd3.y - pd3.z * pd3.z;

    pd_center.y = (a1 * c2 * d3 - a1 * c3 * d2 - a2 * c1 * d3 + a2 * c3 * d1 + a3 * c1 * d2 - a3 * c2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    pd_center.z = -(a1 * b2 * d3 - a1 * b3 * d2 - a2 * b1 * d3 + a2 * b3 * d1 + a3 * b1 * d2 - a3 * b2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    pd_center.x = -(b1 * c2 * d3 - b1 * c3 * d2 - b2 * c1 * d3 + b2 * c3 * d1 + b3 * c1 * d2 - b3 * c2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    return pd_center;
}