C#自定义类型强制转换实例分析

public class MyCurrency{  public uint Dollars;  public ushort Cents;  public MyCurrency(uint dollars, ushort cents)  {    this.Dollars = dollars;    this.Cents = cents;  }  public override string ToString()  {    return string.Format(      "${0}.{1}", Dollars, Cents    );  }  //提供MyCurrency到float的隐式转换  public static implicit operator float(MyCurrency value)  {    return value.Dollars + (value.Cents / 100.0f);  }  //把float转换为MyCurrency,不能保证转换肯定成功,因为float可以  //存储负值,而MyCurrency只能存储正数  //float存储的数量级比uint大的多，如果float包含一个比unit大的值，  //将会得到意想不到的结果，所以必须定义为显式转换  //float到MyCurrency的显示转换  public static explicit operator MyCurrency(float value)  {    //checked必须加在此处，加在调用函数外面是不会报错的，    //因为溢出的异常是在强制转换运算符的代码中发生的    //Convert.ToUInt16是为了防止丢失精度    //该段内容很重要，详细参考"C#高级编程(中文第七版) 218页说明"    checked    {      uint dollars = (uint)value;      ushort cents = Convert.ToUInt16((value - dollars) * 100);      return new MyCurrency(dollars, cents);    }  }}

private void btn_测试自定义类型强制转换_Click(object sender, EventArgs e){  MyCurrency tmp = new MyCurrency(10, 20);  //调用MyCurrency到float的隐式转换  float fTmp = tmp;  MessageBox.Show(fTmp.ToString());  float fTmp2 = 200.30f;  //调用float到MyCurrency的显示转换  MyCurrency tmp2 = (MyCurrency)fTmp2;  MessageBox.Show(tmp2.ToString());}