VB split的用法

我用VB5读取一个文本文件，由于需逐行读取再分析计算。可是这种读入文件速度对大文件时特别慢。能否把所有文件信息全部读入缓冲区，再处理。可是又如何保证每行每行地分析数据呢。

回答:

先使用Get语句将文件读到一个字符串中，然后，使用Split函数进行逐行的分解。之所以使用Get语句，而不使用Input函数，请参考QA000051 "VB 5提示错误："输入超出文件尾""。下面是一个示例。

Private Sub Command1_Click()

Dim s As String

s = String(FileLen("c:\a.txt"), " ")

Open "c:\a.txt" For Binary As 1

Get #1, , s

Close 1

v = Split(s, vbCrLf)

Dim i

For i = 0 To UBound(v)

List1.AddItem v(i)

Next

End Sub

Public Function Split(ByVal sIn As String, Optional sDelim As _

String, Optional nLimit As Long = -1, Optional bCompare As _

VbCompareMethod = vbBinaryCompare) As Variant

Dim sRead As String, sOut() As String, nC As Integer

If sDelim = "" Then

Split = sIn

End If

sRead = ReadUntil(sIn, sDelim, bCompare)

Do

ReDim Preserve sOut(nC)

sOut(nC) = sRead

nC = nC + 1

If nLimit <> -1 And nC >= nLimit Then Exit Do

sRead = ReadUntil(sIn, sDelim)

Loop While InStr(1, sIn, sDelim, bCompare) > 0

ReDim Preserve sOut(nC)

sOut(nC) = sIn

Split = sOut

End Function

Public Function ReadUntil(ByRef sIn As String, _

sDelim As String, Optional bCompare As VbCompareMethod _

= vbBinaryCompare) As String

Dim nPos As String

nPos = InStr(1, sIn, sDelim, bCompare)

If nPos > 0 Then

ReadUntil = Left(sIn, nPos - 1)

sIn = Mid(sIn, nPos + Len(sDelim))

End If

End Function

Visual Basic 复制代码

Imports System

Public Class SplitTest

Public Shared Sub Main()

Dim words As String = "this is a list of words, with: a bit of punctuation."

Dim split As String() = words.Split(New [Char]() {" "c, ","c, "."c, ":"c})

Dim s As String

For Each s In split

If s.Trim() <> "" Then

Console.WriteLine(s)

End If

Next s

End Sub 'Main

End Class 'SplitTest

Visual Basic（用法）

Dim instance As String

Dim separator As Char()

Dim returnValue As String()

returnValue = instance.Split(separator)