4、使用可空类型 public static Vector operator +(vector op1, Vector op 2) try double newX=op1.R Value Sin(op1. ThetaRad i ans Value) op2R. Value Sin(op2. ThetaRadi ans. value double newY= op1. R Value Cos(op1. ThetaRadi ans. Value) op2R Value Cos(op2. ThetaRadi ans. value double newr Sart (newX newX newY newY) double new Theta Atan2(newX, newY)* 180.0/ PI return new Vector(newR, new Theta) catch I return new Vector(nul l, nul D);j publ ic static Vector operator -(Vector op1)=>new Vector (-op1. R, op1. Theta) public static Vector operator -(Vector op1, Vector op2)=>op1 + (op 2) ubl ic overr ide str ing toStr ing o str ing rStr =R HasValue R. ToStr ingo str ing thetaStr Theta Has Value Theta. ToStr ingo: "nul I return str ing Format(s"(rStr, IthetaStr))")4、使用可空类型