计算字符串中特定字符出现次数的最简单方法是什么？
即我需要写一个函数countTheCharacters()
str="the little red hen" count=countTheCharacters(str,"e") 'count should equal 4 count=countTheCharacters(str,"t") 'count should equal 3
最直接的是简单地循环字符串中的字符：
Public Function CountCharacter(ByVal value As String,ByVal ch As Char) As Integer
Dim cnt As Integer = 0
For Each c As Char In value
If c = ch Then cnt += 1
Next
Return cnt
End Function
用法：
count = CountCharacter(str,"e"C)
另一种几乎同样有效并且给出较短代码的方法是使用LINQ扩展方法：
Public Function CountCharacter(ByVal value As String,ByVal ch As Char) As Integer Return value.Count(Function(c As Char) c = ch) End Function