C#字符操作一些代码

string full = "AAAAAACCGGGG";              string sub = "AAAA";              int matchNumber = 0;              int currentPos = 0;              while (full.IndexOf(sub, currentPos) != -1)              {                  currentPos ++;                  matchNumber++;              }  

string ab;             for (int i = 0; i < data.Count - 1; i++)             {                 int k = 0;                 ab = data[i] + "" + data[i + 1];//截取的两个字符                // 对比                 for (int j = i; j < data.Count - 1; j++)                 {                     //对比两字符                     string cAb = data[j] + "" + data[j + 1];                     if (ab.Equals(cAb))                     {                         k++;                     }                 } 

//计算每个字符出现的次数             foreach (char ch in data)             {                 //字符出现2次及以上                 if (save.ContainsKey(ch))                 {                     int i = (int)save[ch];                     save.Remove(ch);                     save.Add(ch, ++i);                 }                 //字符第一次出现                 else                     save.Add(ch, 1);             }              //计算每两个字符             string ab;             for (int i = 0; i < data.Count - 1; i++)             {                 ab = data[i] + "" + data[i + 1];//截取的两个字符                 //用hashtable做对比并储存                 if (save.ContainsKey(ab))                 {                     save[ab] = ((int)save[ab]) + 1;                 }                 else                 {                     save.Add(ab, 1);                 }             }