如何计算字符串中字符的第 n 次出现（位置）？

Question

我正在尝试使用 vb.net winforms 制作刽子手游戏（用于学校项目），我想知道如何计算字符串中字符出现的第 n 个位置。

dim randomstring as string = "Whosebug"
 For int As Integer = 0 To randomstring.Length - 1
        Label2.Text &= "_  "
    Next

如果我想在随机字符串中找到“o”的出现，我希望输出为“6, 12”，然后我会将 label2.text 中的下划线替换为其中的 o具体位置。有什么方法可以做到这一点，甚至有更好的方法吗？

Answer 1

.NET 数组以索引 0 开头。String 是 Char 的数组。这就是 IndexOf 的工作原理，以及我们如何逐个字符地遍历字符串。字符串被视为数组。

'To find the first index
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim s = "The quick brown fox jumped over the lazy dogs."
    Dim i = s.IndexOf("o")
    MessageBox.Show(i.ToString)
End Sub

'To find index of all occurances
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    Dim s = "The quick brown fox jumped over the lazy dogs."
    Dim i As Integer
    Dim lst As New List(Of Integer)
    For Each c In s
        If c = "o" Then
            lst.Add(i)
        End If
        i += 1
    Next
    'See what is in the list
    For Each item In lst
        Debug.Print(item.ToString)
    Next
    'Prints in Immediate Window
    '12
    '17
    '27
    '42
End Sub

如何计算字符串中字符的第 n 次出现（位置）？

How to count the nth occurence (position) of a character in a string?

vb.net

string

character

winforms