在VB.NET中需要帮助打开和关闭文件。 [英] Need a assist with opening and closing files in VB.NET.

问题描述

Greetings,

     I'm a old time VBA and Basic programmer. I need a assist with opening and closing files in VB.NET. The CSV and the code is below. Can someone assist me with converting this to VB.NET. I will appreciated it. Thanks 





"James","ll","ddd",473.57,12700.00,0.03,,,"jan"
"Frank","rr","lll",392.15,8600.00,0.04,"GTD","o","feb"
"Nikola","C","ff",366.55,6900.00,0.05,,,"march"
"Harrison","df","rr",360.76,6900.00,0.05,,,"aug"
"Mark","tm","gg",358.60,8200.00,0.04,,,"julu"


open "C:\Users\john\Desktop\data5.txt" for input as 1
open "C:\Users\john\Desktop\output.txt" for output as 2


Input #1,name1,code1,code2,num1,num2,num3,num4,scode1,scode2,date1


'Calcuations section


write #2,Name1, Evaluation


close 1
close 2

我的尝试：



我试过

What I have tried:

I have tried

FileOpen(filenum, "data5.txt", OpenMode.Input)

推荐答案

例如：

For example like this :

Imports System.IO



Public Sub LoadData()

        Dim myFile As String = "c:\Data\myFile.DAT"

        Dim fs As FileStream = Nothing
        Dim CSV As StreamReader = Nothing
        Dim rowdata As String

        Try
            ' open the File
            fs = New FileStream(myFile, FileMode.Open, FileAccess.Read)
            CSV = New StreamReader(fs)

            ' load one row
            rowdata = CSV.ReadLine  

            CSV.Close()

        Catch ex As Exception
            CSV.Close()
        End Try

    End Sub

在VB.NET中读写文件与VB6 / VBA有显着差异。它可能更接近 FileSystemObject [ ^ ]，这是唯一的方法从VBScript读取和写入文件。



MSDN有一些很好的文档：

如何：从Visual Basic中的文本文件中读取 [ ^ ]

如何：在Visual Basic中使用StreamWriter将文本写入文件 [ ^ ]



在这种情况下，您似乎正在尝试从CSV文件中读取。有一个内置的类来帮助解决这个问题，或者你可以使用第三方库。

如何：在Visual Basic中读取逗号分隔的文本文件 [ ^ ]

CsvHelper [ ^ ]



因此，例如：

Reading and writing files in VB.NET is significantly different to VB6 / VBA. It's probably closer to the FileSystemObject[^], which was the only way to read and write files from VBScript.

MSDN has some good documentation:
How to: Read From Text Files in Visual Basic[^]
How to: Write Text to Files with a StreamWriter in Visual Basic[^]

In this case, it looks like you're trying to read from a CSV file. There is a built-in class to help with this, or you can use a third-party library.
How to: Read From Comma-Delimited Text Files in Visual Basic[^]
CsvHelper[^]

So, for example:

Using reader As New Microsoft.VisualBasic.FileIO.TextFieldParser("C:\Users\john\Desktop\data5.txt")
    reader.TextFieldType = FileIO.FieldType.Delimited
    reader.SetDelimiters(",")
    
    Using writer As New StreamWriter("C:\Users\john\Desktop\output.txt")
        While Not reader.EndOfData
            Dim currentRow As String() = reader.ReadFields()
            Dim name1 As String = currentRow(0)
            Dim code1 As String = currentRow(1)
            Dim code2 As String = currentRow(2)
            
            ' Converting strings to numbers :- 
            ' this can throw an exception if the string is not a valid number.
            Dim num1 As Double = Double.Parse(currentRow(3))
            Dim num2 As Double = Double.Parse(currentRow(4))
            Dim num3 As Double = Double.Parse(currentRow(5))
            Dim num4 As Double = Double.Parse(currentRow(6))
            
            Dim scode1 As String = currentRow(7)
            Dim scode2 As String = currentRow(8)
            Dim date1 As String = currentRow(9)
            
            ' Calcuations section
            
            writer.WriteLine("""{0}"",""{1}""", name1, Evaluation)
        End While
    End Using
End Using

使用Statement（Visual Basic） [ ^ ]

Double.Parse方法（系统） [ ^ ]

String.Format Method（System） [ ^ ] （解释传递给 WriteLine的看起来很滑稽的字符串方法）

Using Statement (Visual Basic)[^]
Double.Parse Method (System)[^]
String.Format Method (System)[^] (explains the funny-looking string passed to the WriteLine method)

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