vb.net - 字符串中区分大小写/不区分大小写的搜索文本

Question

我一直在使用 text.indexof() 来查看一个字符串是否位于另一个字符串内，但是是否可以执行区分大小写/不区分大小写的搜索选项？我一直在谷歌周围寻找，但运气不佳。

如果它可以计算字符串中出现的次数，那将是一个巨大的收获!

Answer 1

IndexOf 有几个重载需要 StringComparison参数，允许您指定各种区域性和区分大小写选项。

例如:

Dim idx As Integer = haystack.IndexOf(needle, StringComparison.OrdinalIgnoreCase)

至于计算出现次数，没有内置的东西，但自己做起来非常简单:

Dim haystack As String = "The quick brown fox jumps over the lazy dog"
Dim needle As String = "th"
Dim comparison As StringComparison = StringComparison.OrdinalIgnoreCase

Dim count As Integer = CountOccurrences(haystack, needle, comparison)

' ...

Function CountOccurrences(ByVal haystack As String, ByVal needle As String, _
                          ByVal comparison As StringComparison) As Integer
    Dim count As Integer = 0
    Dim index As Integer = haystack.IndexOf(needle, comparison)
    While index >= 0
        count += 1
        index = haystack.IndexOf(needle, index + needle.Length, comparison)
    End While

    Return count
End Function