1 public class Vector : IFormattable 2     { 3         public double X { get; set; } 4         public double Y { get; set; } 5         public double Z { get; set; } 6  7         public double Norm() 8         { 9             return X * X + Y * Y + Z * Z;10         }11 12         public override string ToString()13         {14             return "(" + X + "," + Y + "," + Z + ")";15         }16 17         public string ToString(string format, IFormatProvider formatProvider)18         {19             if (format == null)20             {21                 return ToString();22             }23 24             string formatUpper = format.ToUpper();25 26             switch (formatUpper)27             {28                 case "N":29                     return "|| " + Norm().ToString() + " ||";30                 case "VE":31                     return string.Format("({0:E},{1:E},{2:E})", X, Y, Z);32                 case "IJK":33                     var sb = new StringBuilder(X.ToString(), 30);34                     sb.AppendFormat(" i + ");35                     sb.AppendFormat(Y.ToString());36                     sb.AppendFormat(" j + ");37                     sb.AppendFormat(Z.ToString());38                     sb.AppendFormat(" k");39                     return sb.ToString();40                 default:41                     return ToString();42             }43         }44     }

1 static void Main(string[] args)2         {3             Vector vector1 = new Vector { X = 3, Y = 4, Z = 5 };4             Vector vector2 = new Vector { X = 5, Y = 4, Z = 3 };5             Console.WriteLine("In IJK format, v1 is {0,10:IJK},V2 is {1,10:IJK}", vector1, vector2);6 7             8             Console.ReadKey();9         }