字符串格式化

using System; using System.Collections.Generic; using System.Text; using System.Text; namespace Wrox.ProCSharp.FormattableVector { class MainEntryPoint { static void Main() { Vector v1 = new Vector(1, 32, 5); Vector v2 = new Vector(845.4, 54.3, -7.8); Console.WriteLine("/nIn IJK format,/nv1 is {0,30:IJK}/nv2 is {1,30:IJK}", v1, v2); Console.WriteLine("/nIn default format,/nv1 is {0,30}/nv2 is {1,30}", v1, v2); Console.WriteLine("/nIn VE format/nv1 is {0,30:VE}/nv2 is {1,30:VE}", v1, v2); Console.WriteLine("/nNorms are:/nv1 is {0,20:N}/nv2 is {1,20:N}", v1, v2); } } struct Vector : IFormattable { public double x, y, z; public Vector(double x, double y, double z) { this.x = x; this.y = y; this.z = z; } public string ToString(string format, IFormatProvider formatProvider) { if (format == null) return ToString(); string formatUpper = format.ToUpper(); switch (formatUpper) { case "N": return "|| " + Norm().ToString() + " ||"; case "VE": return String.Format("( {0:E}, {1:E}, {2:E} )", x, y, z); case "IJK": StringBuilder sb = new StringBuilder(x.ToString(), 30); sb.Append(" i + "); sb.Append(y.ToString()); sb.Append(" j + "); sb.Append(z.ToString()); sb.Append(" k"); return sb.ToString(); default: return ToString(); } } public Vector(Vector rhs) { x = rhs.x; y = rhs.y; z = rhs.z; } public override string ToString() { return "( " + x + " , " + y + " , " + z + " )"; } public double this[uint i] { get { switch (i) { case 0: return x; case 1: return y; case 2: return z; default: throw new IndexOutOfRangeException( "Attempt to retrieve Vector element" + i); } } set { switch (i) { case 0: x = value; break; case 1: y = value; break; case 2: z = value; break; default: throw new IndexOutOfRangeException( "Attempt to set Vector element" + i); } } } /* public static bool operator == (Vector lhs, Vector rhs) { if (lhs.x == rhs.x && lhs.y == rhs.y && lhs.z == rhs.z) return true; else return false; }*/ private const double Epsilon = 0.0000001; public static bool operator ==(Vector lhs, Vector rhs) { if (System.Math.Abs(lhs.x - rhs.x) < Epsilon && System.Math.Abs(lhs.y - rhs.y) < Epsilon && System.Math.Abs(lhs.z - rhs.z) < Epsilon) return true; else return false; } public static bool operator !=(Vector lhs, Vector rhs) { return !(lhs == rhs); } public static Vector operator +(Vector lhs, Vector rhs) { Vector Result = new Vector(lhs); Result.x += rhs.x; Result.y += rhs.y; Result.z += rhs.z; return Result; } public static Vector operator *(double lhs, Vector rhs) { return new Vector(lhs * rhs.x, lhs * rhs.y, lhs * rhs.z); } public static Vector operator *(Vector lhs, double rhs) { return rhs * lhs; } public static double operator *(Vector lhs, Vector rhs) { return lhs.x * rhs.x + lhs.y + rhs.y + lhs.z * rhs.z; } public double Norm() { return x * x + y * y + z * z; } } }