如果你需要找到总元音数，不要在循环内使用break，它会退出在第一个字符之后

  for （ int  x =  0 ; x <  r.Length; x ++）
 {
 if （vow.Contains（r [x]））
 {
 count ++; 
} 
} 
 Console.Write（ 元音数：{0} ，count）; 

如果你使用Linq，这很容易：

  //   required  
使用 Linq; 

 string  r = Console.ReadLine（）; 

 int  count = r.Count（ch = >    aeiou .Contains（ch））; 

 Console.WriteLine（ 元音数：{0}，count ）; 

string r;
            r = Console.ReadLine();
            int count = 0;
            char[] vow = new char[] { 'a', 'e', 'i', 'o', 'u' };
            string res = new string(vow);
            for (int x = 0; x < r.Length; x++)
            {

                if (res.Contains(r[x]))
                {
                    count++;

                }
                Console.Write("vowel count:{0}", count);
                break;
            }

if you need to find total vowel count, don't use break inside the loop, it will exit after first character

for (int x = 0; x < r.Length; x++)
{
    if (vow.Contains(r[x]))
    {
        count++;
    }
}
Console.Write("vowel count:{0}", count);

If you use Linq, this gets very easy:

// required
using Linq;

string r = Console.ReadLine();

int count = r.Count(ch => "aeiou".Contains(ch));

Console.WriteLine("vowel count:{0}", count);