C#统计字符串中字符出现的次数

方法1.自定义类

class CharNum
        {
private char c;
private int num;


public char C
            {
get { return c; }
            }

public int Num
            {
get { return num; }
set { num = value; }
            }

public CharNum(char ch)
            {
this.c = ch;
this.num = 1;
            }
        }
static void Main(string[] args)
        {
/* */string s = "abbbcgg";
            IList<char> alist = new List<char>();
for (int i = 0; i < s.Length; i++)
            {
if (!alist.Contains(s[i]))
                    alist.Add(s[i]);
            }
char[] c = (char[])alist.ToArray();
int length = 0;
            CharNum[] data = new CharNum[c.Length];
for (int j = 0; j < s.Length; j++)
            {
                CharNum cn = new CharNum(s[j]);
bool plus = false;
if (length == 0)
                {
                    data[length] = cn;
                    length++;
                }
else
                {
for (int k = 0; k < length; k++)
                    {
if (data[k].C == cn.C)
                        {
                            data[k].Num++;
                            plus = true;
break;
                        }
                    }
if (!plus)
                    {
                        data[length] = cn;
                        length++;
                    }
                }
            }
for (int i = 0; i < data.Length; i++)
            {
                Console.WriteLine("{0}:{1}",data[i].C.ToString(), data[i].Num.ToString());
            }
            Console.ReadKey();
}

方法2：键值集合 Dictionary<char, int>

                Dictionary<char, int> dic = new Dictionary<char, int>();
                String s = "aaabbs";
char[] chardata = s.ToCharArray();

foreach (char c in chardata)
                {
if (!dic.ContainsKey(c))
                    {
                        dic.Add(c, 1);
                    }
else
                    {
                        dic[c] = dic[c] + 1;
                    }
                }
foreach (KeyValuePair<char, int> item in dic)
                {
                    Console.WriteLine("{0}出现{1}次", item.Key, item.Value);
                }
                Console.ReadLine();

方法3：哈希表

                Hashtable ht = new Hashtable();
string sr = "aaabbcddddd";
char[] cr = sr.ToCharArray();
foreach (char ch in cr)
                {
if (ht.ContainsKey(ch))
                    {
int i = (int)ht[ch];
                        ht.Remove(ch);
                        ht.Add(ch, ++i);
                    }
else
                        ht.Add(ch, 1);
                }
foreach (DictionaryEntry dicEntry in ht)
                {
                    Console.WriteLine("{0}出现{1}次", dicEntry.Key, dicEntry.Value);
                }
                ArrayList alist = new ArrayList(ht.Values);
                alist.Sort();
object o = (object)alist[alist.Count - 1];
foreach (DictionaryEntry dicEntry in ht)
                {
if (dicEntry.Value == o)
                    {
string str = dicEntry.Key.ToString();
                        Console.WriteLine("出现次数最多的字符:{0}，共{1}次", str, o.ToString());
break;
                    }
                }
                Console.ReadLine();

方法4：LINQ

            string s = "aaabccccef";
char[] c = s.ToCharArray();
var cc = c.GroupBy(e => e).OrderByDescending(e => e.Count()).ToList();
for (int i = 0; i < cc.Count; i++)
            {
                Console.WriteLine("{0}\t{1}", cc[i].Key.ToString(), cc[i].Count().ToString());
            }
var ccc = c.GroupBy(e => e).OrderByDescending(e => e.Count()).First().ToList();

            Console.WriteLine("{0}出现{1}次！", ccc[0].ToString(), ccc.Count().ToString());
            Console.ReadKey();