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  1. using System;
  2. using System.Linq;
  3.  
  4. public class Test
  5. {
  6.     private static void Assert (bool same)
  7.     {
  8.         Console.WriteLine(same);
  9.     }
  10.  
  11.     private static byte[] ConvertHexToBytes(string input)
  12.     {
  13.         var result = new byte[(input.Length + 1) / 2];
  14.         var offset = 0;
  15.         if (input.Length % 2 == 1) {
  16.             // If length of input is odd, the first character has an implicit 0 prepended.
  17.             result[0] = (byte)Convert.ToUInt32(input[0] + "", 16);
  18.             offset = 1;
  19.         }
  20.         for (int i = 0; i < input.Length / 2; i++) {
  21.             result[i + offset] = (byte)Convert.ToUInt32(input.Substring(i * 2 + offset, 2), 16);
  22.         }
  23.         return result;
  24.     }
  25.  
  26.     private static int HexToInt(char c)
  27.     {
  28.         switch (c) {
  29.             case '0': 
  30.                 return 0;
  31.             case '1': 
  32.                 return 1;
  33.             case '2': 
  34.                 return 2;
  35.             case '3': 
  36.                 return 3;
  37.             case '4': 
  38.                 return 4;
  39.             case '5': 
  40.                 return 5;
  41.             case '6': 
  42.                 return 6;
  43.             case '7': 
  44.                 return 7;
  45.             case '8': 
  46.                 return 8;
  47.             case '9': 
  48.                 return 9;
  49.             case 'a':
  50.             case 'A':
  51.                 return 10;
  52.             case 'b':
  53.             case 'B':
  54.                 return 11;
  55.             case 'c':
  56.             case 'C':
  57.                 return 12;
  58.             case 'd':
  59.             case 'D':
  60.                 return 13;
  61.             case 'e':
  62.             case 'E':
  63.                 return 14;
  64.             case 'f':
  65.             case 'F':
  66.                 return 15;
  67.             default:
  68.                 throw new FormatException("Unrecognized hex char " + c);
  69.         }
  70.     }
  71.  
  72.     private static readonly byte[,] ByteLookup = new byte[,]
  73.     {
  74.         // low nibble
  75.         {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
  76.          0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f},
  77.         // high nibble
  78.         {0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
  79.          0x80, 0x90, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0}
  80.     };
  81.  
  82.     private static byte[] ConvertHexToBytesX(string input)
  83.     {
  84.         var result = new byte[(input.Length + 1) >> 1];
  85.         int lastcell = result.Length - 1;
  86.         int lastchar = input.Length - 1;
  87.         for (int i = 0; i < input.Length; i++) {
  88.             result[lastcell - (i >> 1)] |= ByteLookup[i & 1, HexToInt(input[lastchar - i])];
  89.         }
  90.         return result;
  91.     }
  92.  
  93.     private static void TestConversions() {
  94.         var inputs = new[] { "",
  95.                 "0",
  96.                 "10",
  97.                 "f",
  98.                 "0f",
  99.                 "010",
  100.                 "0ff",
  101.                 "f2ab"
  102.         };
  103.         var i = 0;
  104.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] {  }));
  105.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0 }));
  106.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0x10 }));
  107.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0xf }));
  108.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0xf }));
  109.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0x0, 0x10 }));
  110.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0x0, 0xff }));
  111.         Assert(ConvertHexToBytes(inputs[i++]).SequenceEqual(new byte[] { 0xf2, 0xab }));
  112.         Assert(i == inputs.Length);
  113.         Console.WriteLine("rolfl");
  114.         i = 0;
  115.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] {  }));
  116.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0 }));
  117.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0x10 }));
  118.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0xf }));
  119.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0xf }));
  120.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0x0, 0x10 }));
  121.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0x0, 0xff }));
  122.         Assert(ConvertHexToBytesX(inputs[i++]).SequenceEqual(new byte[] { 0xf2, 0xab }));
  123.         Assert(i == inputs.Length);
  124.     }
  125.     public static void Main()
  126.     {
  127.         TestConversions();
  128.     }
  129. }
Success #stdin #stdout 0.04s 33920KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
True
True
True
True
True
True
True
True
True
rolfl
True
True
True
True
True
True
True
True
True
https://ideone.com/URaxZ4
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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