vb.net 扫描包含给定字符串的行的文本文件，并用另一个字符串替换该行
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Scan text file for line containing a given string and replace the line with another string
提问by 0867532
I want to scan my file for line that contains a particular string "black=" and if there is a match replace it with "blah blah" but I don't know how to do that. Here is what I tried but it does not work.
我想扫描我的文件中包含特定字符串“black=”的行，如果有匹配项，请将其替换为“blah blah”，但我不知道该怎么做。这是我尝试过但不起作用的方法。
Dim myStreamReaderL1 As System.IO.StreamReader
myStreamReaderL1 = System.IO.File.OpenText("C:\File.txt")
myStreamReaderL1.ReadLine()
If myStreamReaderL1.ReadLine.Contains("black=") Then
Button2.Hide()
Else
Return
End If
回答by George
Assuming the input file is not huge, you can read the whole file into a string and change all instances of black=to blah blah
假设输入文件不是很大，你可以读取整个文件转换成字符串，并更改的所有实例black=来blah blah
Dim myStreamReaderL1 As System.IO.StreamReader
Dim myStream As System.IO.StreamWriter
Dim myStr As String
myStreamReaderL1 = System.IO.File.OpenText("C:\File.txt")
myStr = myStreamReaderL1.ReadToEnd()
myStreamReaderL1.Close()
myStr = myStr.Replace("black=", "blah blah")
'Save myStr
myStream = System.IO.File.CreateText("C:\FileOut.txt")
myStream.WriteLine(myStr)
myStream.Close()
EDIT:a slightly more efficient (less code) version with ReadAllText per Christian Sauer's suggestion.
编辑：根据Christian Sauer的建议，使用 ReadAllText 的稍微更高效（更少代码）的版本。
EDIT2:if I am trying to be efficient, lets optimize everything. One line is enough, me thinks.
EDIT2：如果我想提高效率，让我们优化一切。一根线就够了，我想。
If you want to save into a file:
如果要保存到文件中：
System.IO.File.WriteAllText("C:\FileOut.txt", System.IO.File.ReadAllText("C:\File.txt").Replace("black=", "blah blah"))
If you simply want to store into a string to be used later:
如果您只是想存储到一个字符串中以备后用：
Dim myStr As String = System.IO.File.ReadAllText("C:\File.txt").Replace("black=", "blah blah")
