在 txt 文件中查找单词并阅读上一行 VB.NET

Question

我正在 VB 中逐行读取 txt 文件以查找“无法”一词。这么多工作。代码在这里：

Imports System
Imports System.IO
Imports PartMountCollector.HandMount_WebReference
Imports System.Threadingtime
Imports eCenter.Motor.VBConnect

Module Program
    Sub Main(args As String())
        Dim unUpdate As String = "Unable"
        Dim time = DateTime.Now
        Dim yesterday = time.AddDays(-1)
        Dim format As String = "yyyyMMdd"
        Dim words As String()

        For Each Line As String In File.ReadLines("C:\Users\te-smtinternal\Desktop\ReStockLog\" + time.ToString(format) + ".txt")
            words = Split(Line)
            If Line.Contains(unUpdate) = True Then
                Console.WriteLine("Exist")
                'Read previous line looking for "Success"'
            End If
            Console.WriteLine("not found")
        Next
    End Sub
End Module

现在我需要能够识别这一行 并阅读上一行 ，寻找“成功”一词。

如有任何帮助，我们将不胜感激

Answer 1

你只需要在循环外声明一个变量来存储上一行。我在这里将其命名为 previousLine...

Const unUpdate As String = "Unable"
Dim time = DateTime.Now
Const format As String = "yyyyMMdd"

Dim previousLine as String = Nothing
For Each currentLine As String In File.ReadLines("C:\Users\te-smtinternal\Desktop\ReStockLog\" + time.ToString(format) + ".txt")
    If currentLine.Contains(unUpdate) Then
        Console.WriteLine("Exist")

        If previousLine Is Nothing Then
            ' The very first line of input contains unUpdate
        Else If previousLine.Contains("Success")
            ' A line after the first line of input contains unUpdate
        End If
    Else
        Console.WriteLine("not found")
    End If

    previousLine = currentLine
Next

在每次循环迭代结束时，currentLine 变为 previousLine，如果有另一次迭代，它将读取 currentLine 的新值。

另请注意，在...

If Line.Contains(unUpdate) = True Then

...您不需要 = True 比较，因为 Contains() 已经 returns 一个 Boolean.

Answer 2

您可以读取所有行，然后遍历它们，这样您就可以访问上一行，而不是尝试一次处理每一行，例如：

Dim lines = IO.File.ReadAllLines(file_name)
dim previous_line as string = ""

for x as integer = 0 to lines.count-1
  if lines(x).ToString.Contains("unable") then previous_line = lines(x-1).ToString
next

当然，您需要处理在第一行找到匹配项的异常，这会抛出索引错误。所以你只需要添加一个检查来确保 x > 0.

在 txt 文件中查找单词并阅读上一行 VB.NET

Find word in a txt file and read previous line VB.NET

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