Question

如何判断一个数组中相同数的个数?比如int[]nums=new int[5]{1,1,3,1,3}.1有三个,3有两个,C#该怎么判断呢

Answer 1

linq 一句话搞定

int[] nums = new int[5] { 1, 1, 3, 1, 3 };

var d = from n in nums group n by n into g select new { Key = g.Key, Count = g.Count() };

Answer 2

int[] a = new int[] { 1,1,2,4,6,6,3,1};
Hashtable ht = new Hashtable();
for (int i = 0; i < a.Length; i++)
{
int b = a[i];
int count = 0;
int flag = 0;
#region 判断哈希表中已经存在该值，如果已存在，不再进行比较
if (ht.Count > 0)
{
foreach (System.Collections.DictionaryEntry de in ht)
{
if (de.Key.ToString() == a[i].ToString())
{
flag = 1;
break;
}
}
if (flag == 1)
{
continue;
}
}
#endregion
#region 比较，和b相同的值有几个，写入哈希表
for (int j = 0; j < a.Length; j++)
{
if (i != j)
{
if (b == a[j])
{
count++;
}
}
}
ht.Add(b.ToString(), count.ToString());
#endregion
}
#region 输出结果
string result = "结果：<br/>";
foreach (System.Collections.DictionaryEntry de in ht)
{
result += de.Key.ToString() + "有" + de.Value.ToString() + "个相同<br/>";
}
#endregion
Response.Write(result);

结果：

4有0个相同

6有1个相同

1有2个相同

2有0个相同

3有0个相同

Answer 3

写的不是很好，希望对你有所帮助
int[] nNumlist = new int[] { 1, 2, 3, 4, 1, 1, 1, 2, 3, 4 };
Array.Sort(nNumlist);
int nTemp = nNumlist[0];
int nCount = 0;
for (int i = 0; i < nNumlist.Length; i++)
{
if (nTemp != nNumlist[i])
{
Console.WriteLine("Count of Number {0} is {1}", nTemp, nCount);
nTemp = nNumlist[i];
nCount = 1;
}
else
{
nCount++;
}
if (i == nNumlist.Length - 1)
{
Console.WriteLine("Count of Number {0} is {1}", nNumlist[i], nCount);
}
}