VB.NET打开二进制文件用fileopen完成,打开二进制文件的形式为:openmode.binary
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读取二进制文件用的是fileget方法,写入二进制文件用的是fileput方法。
应用示例:将一批随机数保存在一个dat文件中,然后再将其提取到文本框中。
二进制文件的读写一批随机数的存取,程序为:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim x, i, fn As Integer
Dim s As String = ""
fn = FreeFile()
FileOpen(fn, "d:\data.dat", OpenMode.Binary)
For i = 1 To 8
x = Int(Rnd() * 100)
s = s + Str(x)
FilePut(fn, x)
Next
FileClose(fn)
TextBox1.Text = s
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim x, fn As Integer
Dim s As String = ""
fn = FreeFile()
FileOpen(fn, "d:\data.dat", OpenMode.Binary)
Do While Not EOF(fn)
FileGet(fn, x)
s = s + Str(x) + " "
Loop
FileClose(fn)
TextBox1.Text = s
End Sub
1、实现上传按钮方法代码。
2、判断图片对象是否为空代码。
3、取得数据库字段 dt.Rows(0)("Pic")方法代码。
4、字节数组转换为Image类型方法代码。
5、处理SQL中操作Image类型方法代码。
6、实现的上传结果。
写入:Dim sr As New IO.StreamWriter(Application.StartupPath "/写入的文本.txt")
sr.WriteLine("写入的内容") sr.Close()读取:If (File.Exists(Application.StartupPath "/msg.txt")) Then
Dim fm As New IO.FileStream(Application.StartupPath "/读取的文本.txt", FileMode.Open)
Dim sr As IO.StreamReader = New IO.StreamReader(fm)
Do While sr.Peek() = 0
TextBox1.Text = sr.ReadLine() (读取文本到文本框)
Loop end if
imports System.IO
读取指定文件
'
'读取指定文本文件
Public Function readtext(ByVal path As String)
If path = "" Then
readtext = "操作失败!"
Exit Function
End If
Try
If File.Exists(path) = True Then
Dim fs As New FileStream(path, FileMode.Open)
Dim sr As New StreamReader(fs)
Dim str As String
str = sr.ReadToEnd.ToString
sr.Close()
fs.Close()
readtext = str
Else
readtext = "操作失败!"
End If
Catch ex As Exception
readtext = "操作失败!"
End Try
End Function
'向指定文件写入数据
Public Function writetext(ByVal path As String, ByVal opi As Integer, ByVal msg As String)
If path = "" Then
writetext = "操作失败!"
Exit Function
End If
Dim op As FileMode
Select Case opi
Case 1
op = FileMode.Append
Case 2
op = FileMode.Create
Case Else
op = FileMode.Create
End Select
Try
If File.Exists(path) = True Then
Dim fs As New FileStream(path, op)
Dim sr As New StreamWriter(fs)
sr.WriteLine(msg)
sr.Close()
fs.Close()
writetext = "操作完成!"
Else
writetext = "操作失败!"
End If
Catch ex As Exception
writetext = "操作失败!"
End Try
End Function
Imports System.IO
Public Class Form1
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Dim sr As New StreamReader("d:\test.csv")
Dim arr1(), arr2(), arr3(), arr4() As Integer
Dim a1, a2, a3, a4 As New ArrayList
Do Until sr.EndOfStream
Dim str As String = sr.ReadLine
Dim s() As String = str.Split(",")
a1.Add(Convert.ToInt32(s(0)))
a2.Add(Convert.ToInt32(s(1)))
a3.Add(Convert.ToInt32(s(2)))
a4.Add(Convert.ToInt32(s(3)))
ListBox1.Items.Add(s(0))
Loop
arr1 = CType(a1.ToArray(GetType(Integer)), Integer())
arr2 = CType(a2.ToArray(GetType(Integer)), Integer())
arr3 = CType(a3.ToArray(GetType(Integer)), Integer())
arr4 = CType(a4.ToArray(GetType(Integer)), Integer())
sr.Close()
End Sub
End Class
1、新建一个标准的VB EXE工程,只有一个Form,Form上有两个按钮:Command1和Command2。
2、双击Command1添加如下代码
Private Sub Command1_Click()
Dim strFile As String
Dim intFile As Integer
Dim strData As String
strFile = "c:\学生成绩.txt"
intFile = FreeFile
Open strFile For Input As intFile
strData = StrConv(InputB(FileLen(strFile), intFile), vbUnicode)
Debug.Print strData
Close intFile
End Sub
3、按F8开始单步调试代码,点击Command1,进入单步调试功能,
4、多次按下F8或直接按下F5运行完成,就完成了读取文本文件内容并输出到立即窗口。