查至整数

Question

我想从一个字符串中得到数字，我就是这么做的。

我想将这个字符转换为数据库的任何一个接口，但是得到以下错误：'/‘应用程序中的服务器错误。

输入字符串的格式不正确。

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.FormatException: Input string was not in a correct format.

代码：

For Each File As FileInfo In New DirectoryInfo(("C:\Folder")).GetFiles("*.aspx", SearchOption.AllDirectories)
    vFileName = File.FullName
                    Dim myChars() As Char = vFileName.ToCharArray()
                    Dim iChar As Integer = Convert.ToInt32(myChars)
                    iChar = Mid(1, 1, iChar)

Answer 1

由于字符串中有多个数字，因此需要分别解析每个数字。

For Each ch As Char In myChars
    If Integer.TryParse(ch, iChar) Then
        Exit For
    End If
Next

Answer 2

不需要转换字符串，您可以以Char值的形式访问字符串中的字符。您可以使用Char.IsDigit检查数字：

vFileName = File.FullName
Dim iChar As Integer = -1
For Each ch As Char In vFileName
  If Char.IsDigit(ch) Then
    iChar = Int32.Parse(ch)
    Exit For
  End If
Next

Answer 3

您可以使用LINQ获取第一个数字，并得到没有数字的指示：

Option Infer On

Imports System.IO

Module Module1

    Sub Main()
        Dim srcDir = "D:\inetpub\wwwroot" ' sample data

        ' Use Directory.EnumerateFiles if you want to get them incrementally, e.g.
        ' showing the list of files using AJAX.

        For Each f In Directory.GetFiles(srcDir, "*.aspx", SearchOption.AllDirectories)

            Dim num = Path.GetFileNameWithoutExtension(f).FirstOrDefault(Function(c) Char.IsDigit(c))

            If num <> Chr(0) Then
                Console.WriteLine("First digit is " & num)
            Else
                Console.WriteLine("No digit.")
            End If

        Next

        Console.ReadLine()

    End Sub

End Module