字符串相似度-C#

之前在做一个任务时, 需要比较字符串的相似度, 最终整理了一个出来, 以下：

  1 /*
  2  * Copyright (c) 2013 Thyiad
  3  * Author: Thyiad
  4  * Create date: 2013/08/08
  5  */
  6
  7 using System;
  8
  9 namespace Thyiad.Utility
 10 {
 11     /// <summary>
 12     /// Operates about string.
 13     /// </summary>
 14     public static class StringUtil
 15     {
 16         /// <summary>
 17         /// Compare with two string, return avg similar degree.
 18         /// </summary>
 19         /// <param name="str1"></param>
 20         /// <param name="str2"></param>
 21         /// <returns>A number of percent.</returns>
 22         public static int StrSim(string str1, string str2)
 23         {
 24             try
 25             {
 26                 if (str1 == null || str2 == null ||
 27                 (str1 == string.Empty && str2 != string.Empty) ||
 28                 (str1 != string.Empty && str2 == string.Empty))
 29                 {
 30                     return 0;
 31                 }
 32                 else if (str1.Equals(str2))
 33                 {
 34                     return 100;
 35                 }
 36
 37                 int similar1 = 0;
 38                 int similar2 = 0;
 39
 40                 similar1 = StrSimSub2(str1, str2);
 41                 similar2 = StrSimSub2(str2, str1);
 42
 43                 return ((similar1 + similar2) / 2);
 44             }
 45             catch (Exception)
 46             {
 47                 throw;
 48             }
 49         }
 50
 51         /// <summary>
 52         /// Compare with two string, return similar degree.
 53         /// </summary>
 54         /// <param name="str1"></param>
 55         /// <param name="str2"></param>
 56         /// <returns>A number of percent.</returns>
 57         private static int StrSimSub2(string str1, string str2)
 58         {
 59             try
 60             {
 61                 int len1, len2;
 62                 int pos1, pos2;
 63                 char char1, char2;
 64                 int val1, val_min, val_max;
 65
 66                 len1 = str1.Length;
 67                 len2 = str2.Length;
 68                 pos1 = 1;
 69                 val1 = 0;
 70
 71                 if (len1 < len2)
 72                 {
 73                     val_max = len2 + 1;
 74                 }
 75                 else
 76                 {
 77                     val_max = len1 + 1;
 78                 }
 79
 80                 while (pos1 <= len1)
 81                 {
 82                     char1 = str1[pos1 - 1];
 83                     pos2 = 1;
 84                     val_min = val_max;
 85                     while (pos2 <= len2)
 86                     {
 87                         char2 = str2[pos2 - 1];
 88                         if (char1 == char2)
 89                         {
 90                             if (Math.Abs(pos1 - pos2) < val_min)
 91                             {
 92                                 val_min = Math.Abs(pos1 - pos2);
 93                             }
 94                         }
 95                         pos2++;
 96                     }
 97                     pos1++;
 98                     val1 = val1 + val_min;
 99                 }
100
101                 return (100 - (val1 * 100 / (len1 * val_max)));
102             }
103             catch (Exception)
104             {
105                 throw;
106             }
107         }
108     }
109 }