6 如何统计一个字符串中特定特定字符串出现的次数

(1) 单个字符的查询
    foreach
(2) 字符串的查询
    RegEx
    
    
示例代码：

static void CountStrings()
{
    string test = "Hello, how are youyou you you you, you you yy?";
    int wordCount = 0;
    int charCount = 0;

    foreach (Match m in Regex.Matches(test, "you"))
    {
        wordCount++;
    }

    foreach (char value in test)
    {
        if (value == 'y')
        {
            charCount++;
        }
    }

    Console.WriteLine("Word count: {0}", wordCount);
    Console.WriteLine("Character count: {0}", charCount);
}